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Sample records for range beam-beam tune

  1. Observed Orbit Effects during Long Range Beam-Beam Studies

    CERN Document Server

    Alemany, R; Buffat, X; Calaga, R; Fitterer, M; Giachino, R; Hemelsoet, GH; Herr, W; Papotti, G; Pieloni, T; Poyer, M; Schaumann, M; Trad, G; Wollmann, D

    2012-01-01

    Possible limitations due to long range beam-beam effects at the LHC have been studied and are presented in this note. With a larger number of bunches and collisions in all interaction points, the crossing angles were reduced to enhance long range beam-beam effects. The analysis of the effects on the dynamic aperture and losses are documented in [1]. This note concentrates on the bunch-by-bunch orbit effects observed during the experiment.

  2. Study of beam-beam long range compensation with octupoles

    CERN Document Server

    Barranco Garcia, Javier; Buffat, Xavier; Tambasco, Claudia

    2017-01-01

    Long range beam-beam effects are responsible for particle losses and define fundamental operational parameters of colliders (i.e. crossing angles, intensities, emittances, ${\\beta}$${^∗}$). In this study we propose octuple magnets as a possible scheme to efficiently compensate long-range beam-beam interactions with a global correction scheme. The impact and improvements on the dynamic aperture of colliding beams together with estimates of the luminosity potentials are dis- cussed for the HL-LHC upgrade and extrapolations made for the FCC project.

  3. Results of long range beam-beam studies and observations during operation in the LHC

    CERN Document Server

    Alemany, R; Buffat, X; Calaga, R; Fitterer, M; Giachino, R; Hemelsoet, GH; Herr, W; Papotti, G; Pieloni, T; Poyer, M; Schaumann, M; Trad, G; Wollmann, D

    2011-01-01

    We studied possible limitations due to the long range beam-beam effects in the LHC. With a larger number of bunches and collisions in all interaction points, we have reduced the crossing angles to enhance long range beam-beam effects to evaluate their influence on dynamic aperture and losses. Experience from operation with reduced separation was analysed and provides additional evidence.

  4. Simulating the Wire Compensation of LHC Long-Range Beam-beam Effects.

    CERN Document Server

    Rijoff, T

    2012-01-01

    The performance of the Large Hadron Collider (LHC) and its minimum crossing angle are limited by long-range beam-beam collisions. Wire compensators can mitigate part of the long-range effects. We perform simulations to explore the efficiency of the compensation at possible wire locations by examining the tune footprint and the dynamic aperture. Starting from the weak-strong simulation code BBTrack we developed a new Lyapunov calculation tool, which seems to better diagnose regular or chaotic particle behavior. We also developed faster ways to execute the simulation and the post-processing. These modifications have allowed us to study different wire positions (longitudinal and transverse), varying wire currents, several wire shapes, and a range of beam-beam crossing angles, in view of a prototype wire installation in the LHC foreseen for 2014/15. Our simulations demonstrate that the wire can provide a good compensation, including for reduced crossing angle. Among the benefits of an LHC wire compensator are a b...

  5. Testing Long-Range Beam-Beam Compensation for the LHC Luminosity Upgrade

    CERN Document Server

    Rijoff, T L

    2012-01-01

    The performance of the Large Hadron Collider (LHC) at CERN and its minimum crossing angle are limited by the effect of long-range beam-beam collisions. A wire compensators can mitigate part of the long-range effects and may allow for smaller crossing angles, or higher beam intensity. A prototype long-range wire compensator could be installed in the LHC by 2014/15. Since the originally reserved position for such a wire compensator is not available for this first step, we explore other possible options. Our investigations consider various longitudinal and transverse locations, different wire shapes, different optics configurations and several crossing angles between the two colliding beams. Simulations are carried out with the weak-strong code BBtrack. New postprocessing tools are introduced to analyse tune footprints and particle stability. In particular, a new method for the Lyapunov coefficient calculation is implemented. Submitted as "Tesi di laurea" at the University of Milano, 2012.

  6. An Alternative High Luminosity LHC with Flat Optics and Long-Range Beam-Beam Compensation

    Energy Technology Data Exchange (ETDEWEB)

    Fartoukh, Stephane [CERN; Valishev, Alexander [Fermilab; Shatilov, Dmitry [BINP, Novosibirsk

    2015-06-01

    In the baseline scenario of the High-Luminosity LHC (HL-LHC), the geometric loss of luminosity in the two high luminosity experiments due to collisions with a large crossing angle is recovered by tilting the bunches in the interaction region with the use of crab cavities. A possible backup scenario would rely on a reduced crossing angle together with flat optics (with different horizontal and vertical $\\beta^{\\ast}$values) for the preservation of luminosity performance. However, the reduction of crossing angle coupled with the flat optics significantly enhances the strength of long-range beam-beam interactions. This paper discusses the possibility to mitigate the long-range beam-beam effects by current bearing wire compensators (or e-lens). We develop a new HL-LHC parameter list and analyze it in terms of integrated luminosity performance as compared to the baseline. Further, we evaluate the operational scenarios using numerical simulations of single-particle dynamics with beam-beam effects.

  7. An Alternative High Luminosity LHC with Flat Optics and Long-Range Beam-Beam Compensation

    CERN Document Server

    AUTHOR|(CDS)2070952; Valishev, Aleksander; Shatilov, Dmitry

    2015-01-01

    In the baseline scenario of the High-Luminosity LHC (HL-LHC), the geometric loss of luminosity in the two high luminosity experiments due to collisions with a large crossing angle is recovered by tilting the bunches in the interaction region with the use of crab cavities. A possible backup scenario would rely on a reduced crossing angle together with flat optics (with different horizontal and vertical β∗ values) for the preservation of luminosity performance. However, the reduction of crossing angle coupled with the flat optics significantly enhances the strength of long-range beam-beam interactions. This paper discusses the possibility to mitigate the long-range beam-beam effects by current bearing wire compensators (or e-lens). We develop a new HL-LHC parameter list and analyze it in terms of integrated luminosity performance as compared to the baseline. Further, we evaluate the operational scenarios using numerical simulations of single-particle dynamics with beam-beam effects.

  8. Long-Range And Head-On Beam-Beam Compensation Studies in RHIC With Lessons for the LHC

    Energy Technology Data Exchange (ETDEWEB)

    Fischer, W.; Luo, Y.; Abreu, N.; Calaga, R.; Montag, C.; Robert-Demolaize, G.; /Brookhaven; Dorda, U.; Koutchouk, J.P.; Sterbini, G.; Zimmermann, F.; /CERN; Kim, H.J.; Sen, T.; Shiltsev, V.; Valishev, A.; /Fermilab; Qiang, J.; /LBL, Berkeley; Kabel, A.; /SLAC

    2011-11-28

    Long-range as well as head-on beam-beam effects are expected to limit the LHC performance with design parameters. They are are also important consideration for the LHC upgrades. To mitigate long-range effects, current carrying wires parallel to the beam were proposed. Two such wires are installed in RHIC where they allow studying the effect of strong long-range beam-beam effects, as well as the compensation of a single long-range interaction. The tests provide benchmark data for simulations and analytical treatments. Electron lenses were proposed for both RHIC and the LHC to reduce the head-on beam-beam effect. We present the experimental long-range beam-beam program at RHIC and report on head-on compensations studies based on simulations.

  9. Long-Range And Head-On Beam-Beam Compensation Studies in RHIC With Lessons for the LHC

    Energy Technology Data Exchange (ETDEWEB)

    Fischer, W.; Luo, Y.; Abreu, N.; Calaga, R.; Montag, C.; Robert-Demolaize, G.; /Brookhaven; Dorda, U.; Koutchouk, J.P.; Sterbini, G.; Zimmermann, F.; /CERN; Kim, H.J.; Sen, T.; Shiltsev, V.; Valishev, A.; /Fermilab; Qiang, J.; /LBL, Berkeley; Kabel, A.; /SLAC

    2011-11-28

    Long-range as well as head-on beam-beam effects are expected to limit the LHC performance with design parameters. They are are also important consideration for the LHC upgrades. To mitigate long-range effects, current carrying wires parallel to the beam were proposed. Two such wires are installed in RHIC where they allow studying the effect of strong long-range beam-beam effects, as well as the compensation of a single long-range interaction. The tests provide benchmark data for simulations and analytical treatments. Electron lenses were proposed for both RHIC and the LHC to reduce the head-on beam-beam effect. We present the experimental long-range beam-beam program at RHIC and report on head-on compensations studies based on simulations.

  10. OBSERVATION OF LONG-RANGE BEAM-BEAM EFFECT IN RHIC AND PLANS FOR COMPENSATION.

    Energy Technology Data Exchange (ETDEWEB)

    FISCHER, W.; CALAGA, R.; DORDA, U.; DOUTCHOUK, J.-P.; ZIMMERMANN, F.; RANJBAR, V.; SEN, T.; SHI, J.; QIANG, J.; KABEL, A.

    2006-06-23

    At large distances the electromagnetic field of a wire is the same as the field produced by a bunch. Such a long-range beam-beam wire compensator was proposed for the LHC, and single beam tests with wire compensators were successfully done in the SPS. RHIC offers the possibility to test the compensation scheme with colliding beams. We report on measurements of beam losses as a function of transverse separation in RHIC at 100 GeV, and comparisons with simulations. We present a design for a long-range wire compensator in RHIC.

  11. RF Wire Compensator of Long-Range Beam-Beam Effects

    CERN Document Server

    Dorda, U; Kroyer, T; Zimmermann, F

    2008-01-01

    The dynamic aperture of the proton beam circulating in the Large Hadron Collider (LHC) is expected to be limited by up to 120 long-range beam-beam encounters. In order to perfectly compensate the LHC long-range beambeam effect for nominal as well as for so-called "PACMAN" bunches, i.e. bunches at the start or end of a bunch train, the strength of a wire compensator should be adjusted for each bunch individually. Here an RF-based compensator is proposed as a practical solution for the PACMAN compensation. We show that this approach also allows relaxing the power and precision requirements compared with those of a pulsed DC device, to a level within the state-of-the-art of RF technology. Furthermore it permits the use of a passive circulator in the tunnel close to the beam and thus a significant reduction of the transmission line length and of the associated multiple reflections. Simulations of dynamic aperture and emittance growth, issues related to RF phase noise, and first experimental results from laborator...

  12. Applications of electron lenses: scraping of high-power beams, beam-beam compensation, and nonlinear optics

    Energy Technology Data Exchange (ETDEWEB)

    Stancari, Giulio

    2014-09-11

    Electron lenses are pulsed, magnetically confined electron beams whose current-density profile is shaped to obtain the desired effect on the circulating beam. Electron lenses were used in the Fermilab Tevatron collider for bunch-by-bunch compensation of long-range beam-beam tune shifts, for removal of uncaptured particles in the abort gap, for preliminary experiments on head-on beam-beam compensation, and for the demonstration of halo scraping with hollow electron beams. Electron lenses for beam-beam compensation are being commissioned in the Relativistic Heavy Ion Collider (RHIC) at Brookhaven National Laboratory (BNL). Hollow electron beam collimation and halo control were studied as an option to complement the collimation system for the upgrades of the Large Hadron Collider (LHC) at CERN; a conceptual design was recently completed. Because of their electric charge and the absence of materials close to the proton beam, electron lenses may also provide an alternative to wires for long-range beam-beam compensation in LHC luminosity upgrade scenarios with small crossing angles. At Fermilab, we are planning to install an electron lens in the Integrable Optics Test Accelerator (IOTA, a 40-m ring for 150-MeV electrons) as one of the proof-of-principle implementations of nonlinear integrable optics to achieve large tune spreads and more stable beams without loss of dynamic aperture.

  13. Correction of the Long-Range Beam-Beam Effect in LHC using Electro-Magnetic Lenses

    CERN Document Server

    Koutchouk, Jean-Pierre

    2001-01-01

    The beams in LHC collide head-on in at most four experimental points. Due to the small bunch spacing, the beams experience more than one hundred 'near-misses' on either side of the collision points. The transverse beam separation at these places, limited by the quadrupole aperture, is in the range of 7 to 13 sigma. The non-linear part of these 'long-range' interactions appears to be the dominant mechanism for beam blow-up or beam loss in simulation. A simple non-linear model of the long-range interactions can be devised. It shows that the latter may be locally corrected with good accuracy using wires as correcting lenses. The non-linearity measured by the tune footprint is reduced by one order of magnitude. Pulsing the correcting lenses cancels the so-called PACMAN effect.

  14. Applications of electron lenses: scraping of high-power beams, beam-beam compensation, and nonlinear optics

    CERN Document Server

    Stancari, Giulio

    2014-01-01

    Electron lenses are pulsed, magnetically confined electron beams whose current-density profile is shaped to obtain the desired effect on the circulating beam. Electron lenses were used in the Fermilab Tevatron collider for bunch-by-bunch compensation of long-range beam-beam tune shifts, for removal of uncaptured particles in the abort gap, for preliminary experiments on head-on beam-beam compensation, and for the demonstration of halo scraping with hollow electron beams. Electron lenses for beam-beam compensation are being commissioned in the Relativistic Heavy Ion Collider (RHIC) at Brookhaven National Laboratory (BNL). Hollow electron beam collimation and halo control were studied as an option to complement the collimation system for the upgrades of the Large Hadron Collider (LHC) at CERN; a conceptual design was recently completed. Because of their electric charge and the absence of materials close to the proton beam, electron lenses may also provide an alternative to wires for long-range beam-beam compens...

  15. Principle of a correction of the long-range beam-beam effect in LHC using electromagnetic lenses

    CERN Document Server

    Koutchouk, Jean-Pierre

    2000-01-01

    Due to the small bunch spacing, the beams in LHC collide not only in the four experimental points but experience more than one hundred 'near-misses'. They occur on either side of the collision points in places where the beam separation is in the range of 7 to 13 sigma. These so-called 'long-range'interactions are more and more recognized to be a drastic mechanism leading to beam blow-up or beam loss even-though the tunes of the particles are under control. We show in this note that, contrary to the head-on-beam interaction, a simple non linear model of the long-range interactions can be devised. This model suggests a rather simple correction principle by electromagnetic lenses, basically a wire, which correct with a good accuracy simultaneously the linear and non-linear perturbations. The correction of the average perturbation over all the bunches seems not demanding. An exact correction of the so-called PACMAN bunches may be done at a frequency an order of magnitude lower than the bunch frequency and is bein...

  16. Compensation of the long-range beam-beam interactions as a path towards new configurations for the High Luminosity LHC

    CERN Document Server

    AUTHOR|(SzGeCERN)390904; Papaphilippou, Yannis; Shatilov, Dmitry

    2015-01-01

    Colliding bunch trains in a circular collider demands a certain crossing angle in order to separate the two beams transversely after the collision. The magnitude of this crossing angle is a complicated function of the bunch charge, the number of long-range beam-beam interactions, of β* and type of optics (flat or round), and possible compensation or additive effects between several low-β insertions in the ring depending on the orientation of the crossing plane at each interaction point. About 15 years ago, the use of current bearing wires was proposed at CERN in order to mitigate the longrange beam-beam effects, therefore offering the possibility to minimize the crossing angle with all the beneficial effects this might have: on the luminosity performance by reducing the need for crab-cavities or lowering their voltage, on the required aperture of the final focus magnets, on the strength of the orbit corrector involved in the crossing bumps, and finally on the heat load and radiation dose deposited in the fi...

  17. Simulations of beam-beam and beam-wire interactions in RHIC

    Energy Technology Data Exchange (ETDEWEB)

    Kim, Hyung J.; Sen, Tanaji; /Fermilab; Abreu, Natalia P.; Fischer, Wolfram; /Brookhaven

    2009-02-01

    The beam-beam interaction is one of the dominant sources of emittance growth and luminosity lifetime deterioration. A current carrying wire has been proposed to compensate long-range beam-beam effects in the LHC and strong localized long-range beam-beam effects are experimentally investigated in the RHIC collider. Tune shift, beam transfer function, and beam loss rate are measured in dedicated experiments. In this paper, they report on simulations to study the effect of beam-wire interactions based on diffusive apertures, beam loss rates, and beam transfer function using a parallelized weak-strong beam simulation code (BBSIMC). The simulation results are compared with measurements performed in RHIC during 2007 and 2008.

  18. Successful Beam-Beam Tuneshift Compensation

    Energy Technology Data Exchange (ETDEWEB)

    Bishofberger, Kip Aaron [Univ. of California, Los Angeles, CA (United States)

    2005-01-01

    The performance of synchrotron colliders has been limited by the beam-beam limit, a maximum tuneshift that colliding bunches could sustain. Due to bunch-to-bunch tune variation and intra-bunch tune spread, larger tuneshifts produce severe emittance growth. Breaking through this constraint has been viewed as impossible for several decades. This dissertation introduces the physics of ultra-relativistic synchrotrons and low-energy electron beams, with emphasis placed on the limits of the Tevatron and the needs of a tuneshift-compensation device. A detailed analysis of the Tevatron Electron Lens (TEL) is given, comparing theoretical models to experimental data whenever possible. Finally, results of Tevatron operations with inclusion of the TEL are presented and analyzed. It is shown that the TEL provides a way to shatter the previously inescapable beam-beam limit.

  19. Limitations due to strong head-on beam-beam interactions (MD 1434)

    CERN Document Server

    Buffat, Xavier; Iadarola, Giovanni; Papadopoulou, Parthena Stefania; Papaphilippou, Yannis; Pellegrini, Dario; Pojer, Mirko; Crockford, Guy; Salvachua Ferrando, Belen Maria; Trad, Georges; Barranco Garcia, Javier; Pieloni, Tatiana; Tambasco, Claudia; CERN. Geneva. ATS Department

    2017-01-01

    The results of an experiment aiming at probing the limitations due to strong head on beam-beam interactions are reported. It is shown that the loss rates significantly increase when moving the working point up and down the diagonal, possibly due to effects of the 10th and/or 14th order resonances. Those limitations are tighter for bunches with larger beam-beam parameters, a maximum total beam-beam tune shift just below 0.02 could be reached.

  20. Halo formation from mismatched beam-beam interactions

    Energy Technology Data Exchange (ETDEWEB)

    Qiang, Ji

    2003-05-23

    In this paper, we report on the halo formation and emittance growth driven by a parametric resonance during mismatched beam-beam collisions. In the regime of the weak-strong beam-beam interaction, if two beams have the same machine tunes, on-axis head-on collisions between a mismatched strong beam and a weak beam will not cause the formation of halo. However, if the two beams collide with an initial offset, the beam-beam force from the mismatched strong beam can cause halo formation and emittance growth in the weak beam. Meanwhile, if two beams have different machine tunes, for opposite charged colliding beams, when the machine tune of the weak beam is smaller than that of strong beam, there is emittance growth in the weak beam. When the machine tune of the weak beam is larger than that of the strong beam, there is little emittance growth. In the regime of strong-strong beam-beam interaction, halo is formed in both beams even when the two beams collide head-on on the axis with equal machine tunes. This puts a strong requirement for a good beam match during the injection to colliders in order to avoid the emittance growth.

  1. Global compensation of long-range beam-beam effects with octupole magnets: dynamic aperture simulations for the HL-LHC case and possible usage in LHC and FCC.

    CERN Document Server

    Barranco Garcia, Javier; CERN. Geneva. ATS Department

    2017-01-01

    The Large Hadron Collider has shown with various experimental verifications that one of the main limitations to the collider performance and to a possible upgrade can come from the long-range beam-beam effects which will define the operational parameters (intensities and emittances) and machine set-up (crossing angles and the minimum beta function at the interaction points). The High Luminosity project aims at very high intensities and will therefore need much larger separations to keep the long range effects weak. In the past several studies of possible active compensators have been carried out and experimental studies are planned to explore such schemes in the LHC. In this note we show the feasibility of using octupole magnets to compensate the effects of long range beam-beam interactions by use of dynamical aperture simulations. A prove of principle of such a compensation scheme is shown for the HL-LHC optics. Preliminary studies for the LHC optics ATS and standard are also presented pointing to the import...

  2. Luminosity Increase at the Incoherent Beam-Beam Limit with Six Superbunches in RHIC

    Science.gov (United States)

    Fischer, W.; Blaskiewicz, M.

    2003-12-01

    By colliding bunches of greater length under a larger angle, the tune spread caused by the beam-beam interaction can be reduced. Assuming a constant limit for the beam-beam tune shift, the bunch intensity can then be raised. In this way, a luminosity increase is possible. We review this strategy for proton beams in RHIC, with two collisions and consider six long bunches. Barrier cavities are used to fill every accelerating bucket of the machine, except for an abort gap, and to create the superbunches bunches at store. Resonances driven by the beam-beam interaction and coherent effects are neglected in this article.

  3. Beam-beam effects in the Tevatron

    Energy Technology Data Exchange (ETDEWEB)

    Shiltsev, V.; Alexahin, Y.; Lebedev, V.; Lebrun, P.; Moore, R.S.; Sen, T.; Tollestrup, A.; Valishev, A.; Zhang, X.L.; /Fermilab

    2005-01-01

    The Tevatron in Collider Run II (2001-present) is operating with 6 times more bunches, many times higher beam intensities and luminosities than in Run I (1992-1995). Electromagnetic long-range and head-on interactions of high intensity proton and antiproton beams have been significant sources of beam loss and lifetime limitations. We present observations of the beam-beam phenomena in the Tevatron and results of relevant beam studies. We analyze the data and various methods employed in operations, predict the performance for planned luminosity upgrades, and discuss ways to improve it.

  4. Observation of Beam-beam Deflections with LHC Orbit Data

    CERN Document Server

    Kozanecki, W; Wenninger, J

    2013-01-01

    The LHC luminosity is calibrated in dedicated fills with van der Meer scans (vdM) of the beams that are performed repeatedly in both planes. During vdM scans the relative separation of the two LHC beams is scanned in a range of ±6 sigma , where sigma is the single beam size, probing the beam-beam deflection over a relatively large range. Orbit data logged parasitically during those scans were analysed and the beam-beam deflections at the IP being scanned could be reconstructed from orbit fits in the LHC arcs surrounding the IP. Despite the small size of the kicks (≤ 1μrad) the coherent beam-beam deflections are clearly resolved. The beam parameters that are extracted from the fit to the beam-beam deflection data were compared to luminosity data fits and they were found to be in good agreement. The closed orbit shift due to the beam-beam kick is also clearly observed in the beam position interpolation at the collision point.

  5. LHC beam-beam compensation using wires and electron lenses

    CERN Document Server

    Dorda, U; Shiltsev, V; Zimmermann, F

    2007-01-01

    We present weak-strong simulation results for a possible application of current-carrying wires and electron lenses to compensate the LHC long-range and head-on beambeam interaction, respectively, for nominal and PACMAN bunches. We show that these measures have the potential to considerably increase the beam-beam limit, allowing for a corresponding increase in peak luminosity.

  6. Tuned range separated hybrid functionals for solvated low bandgap oligomers

    Energy Technology Data Exchange (ETDEWEB)

    Queiroz, Thiago B. de, E-mail: thiago.branquinho-de-queiroz@uni-bayreuth.de; Kümmel, Stephan [Theoretical Physics IV, University of Bayreuth, D-95440 Bayreuth (Germany)

    2015-07-21

    The description of charge transfer excitations has long been a challenge to time dependent density functional theory. The recently developed concept of “optimally tuned range separated hybrid (OT-RSH) functionals” has proven to describe charge transfer excitations accurately in many cases. However, describing solvated or embedded systems is yet a challenge. This challenge is not only computational but also conceptual, because the tuning requires identifying a specific orbital, typically the highest occupied one of the molecule under study. For solvated molecules, this orbital may be delocalized over the solvent. We here demonstrate that one way of overcoming this problem is to use a locally projected self-consistent field diagonalization on an absolutely localized molecular orbital expansion. We employ this approach to determine ionization energies and the optical gap of solvated oligothiophenes, i.e., paradigm low gap systems that are of relevance in organic electronics. Dioxane solvent molecules are explicitly represented in our calculations, and the ambiguities of straightforward parameter tuning in solution are elucidated. We show that a consistent estimate of the optimal range separated parameter (ω) at the limit of bulk solvation can be obtained by gradually extending the solvated system. In particular, ω is influenced by the solvent beyond the first coordination sphere. For determining ionization energies, a considerable number of solvent molecules on the first solvation shell must be taken into account. We demonstrate that accurately calculating optical gaps of solvated systems using OT-RSH can be done in three steps: (i) including the chemical environment when determining the range-separation parameter, (ii) taking into account the screening due to the solvent, and (iii) using realistic molecular geometries.

  7. Tuning Properties and Dynamic Range of Type 1 Vomeronasal Receptors

    Directory of Open Access Journals (Sweden)

    Sachiko eHaga-Yamanaka

    2015-07-01

    Full Text Available The mouse vomeronasal organ expresses chemosensory receptors that detect intra-species as well as inter-species cues. The vomeronasal neurons are thought to be highly selective in their responses. The tuning properties of individual receptors remain difficult to characterize due to the lack of a robust heterologous expression system. Here, we take a transgenic approach to ectopically express two Type 1 vomeronasal receptors in the mouse vomeronasal organ and characterize their responses to steroid compounds. We find that V1rj2 and V1rj3 are sensitive to two sulfated estrogens and can be activated by a broad variety of sulfated and glucuronidated steroids at high concentrations. Individual neurons exhibit narrow range of concentration-dependent activation. Collectively, a neuronal population expressing the same receptor covers a wide dynamic range in their responses to sulfated estrogens. These properties recapitulate the response profiles of endogenous neurons to sulfated estrogens.

  8. Tuning properties and dynamic range of type 1 vomeronasal receptors

    Science.gov (United States)

    Haga-Yamanaka, Sachiko; Ma, Limei; Yu, C. Ron

    2015-01-01

    The mouse vomeronasal organ (VNO) expresses chemosensory receptors that detect intra-species as well as inter-species cues. The vomeronasal neurons are thought to be highly selective in their responses. The tuning properties of individual receptors remain difficult to characterize due to the lack of a robust heterologous expression system. Here, we take a transgenic approach to ectopically express two type 1 vomeronasal receptors in the mouse VNO and characterize their responses to steroid compounds. We find that V1rj2 and V1rj3 are sensitive to two sulfated estrogens (SEs) and can be activated by a broad variety of sulfated and glucuronidated steroids at high concentrations. Individual neurons exhibit narrow range of concentration-dependent activation. Collectively, a neuronal population expressing the same receptor covers a wide dynamic range in their responses to SEs. These properties recapitulate the response profiles of endogenous neurons to SEs. PMID:26236183

  9. Analytical estimation of the beam-beam interaction limited dynamic apertures and lifetimes in e{sup +}e{sup -} circular colliders

    Energy Technology Data Exchange (ETDEWEB)

    Gao, J

    2000-12-01

    Physically speaking, the delta function like beam-beam nonlinear forces at interaction points (IPs) act as a sum of delta function nonlinear multipoles. By applying the general theory established in ref. [1], in this paper we investigate analytically the beam-beam interaction limited dynamic apertures and the corresponding beam lifetimes for both the round and the flat beams. Relations between the beam-beam limited beam lifetimes and the beam-beam tune shifts are established, which show clearly why experimentally one has always a maximum beam-beam tune shift, {zeta}{sub y,max}, around 0.045 for e{sup +}e{sup -} circular colliders, and why one can use round beams to double this value approximately. Comparisons with some machine parameters are given. Finally, we discuss the mechanism of the luminosity reduction due to a definite collision crossing angle. (author)

  10. Nonlinear tuning of microresonators for dynamic range enhancement.

    Science.gov (United States)

    Saghafi, M; Dankowicz, H; Lacarbonara, W

    2015-07-08

    This paper investigates the development of a novel framework and its implementation for the nonlinear tuning of nano/microresonators. Using geometrically exact mechanical formulations, a nonlinear model is obtained that governs the transverse and longitudinal dynamics of multilayer microbeams, and also takes into account rotary inertia effects. The partial differential equations of motion are discretized, according to the Galerkin method, after being reformulated into a mixed form. A zeroth-order shift as well as a hardening effect are observed in the frequency response of the beam. These results are confirmed by a higher order perturbation analysis using the method of multiple scales. An inverse problem is then proposed for the continuation of the critical amplitude at which the transition to nonlinear response characteristics occurs. Path-following techniques are employed to explore the dependence on the system parameters, as well as on the geometry of bilayer microbeams, of the magnitude of the dynamic range in nano/microresonators.

  11. Nonlinear tuning of microresonators for dynamic range enhancement

    Science.gov (United States)

    Saghafi, M.; Dankowicz, H.; Lacarbonara, W.

    2015-01-01

    This paper investigates the development of a novel framework and its implementation for the nonlinear tuning of nano/microresonators. Using geometrically exact mechanical formulations, a nonlinear model is obtained that governs the transverse and longitudinal dynamics of multilayer microbeams, and also takes into account rotary inertia effects. The partial differential equations of motion are discretized, according to the Galerkin method, after being reformulated into a mixed form. A zeroth-order shift as well as a hardening effect are observed in the frequency response of the beam. These results are confirmed by a higher order perturbation analysis using the method of multiple scales. An inverse problem is then proposed for the continuation of the critical amplitude at which the transition to nonlinear response characteristics occurs. Path-following techniques are employed to explore the dependence on the system parameters, as well as on the geometry of bilayer microbeams, of the magnitude of the dynamic range in nano/microresonators. PMID:26345078

  12. Beam-Beam Experience at KEKB

    Energy Technology Data Exchange (ETDEWEB)

    Bane, Karl LF

    2002-11-11

    KEKB has achieved the peak luminosity of 4.1 x 10{sup 33} cm{sup -2} sec{sup -1} and the present capability for delivering integrated luminosity is 224 pb{sup -1}/day. This paper describes (1) the recent performance and the problems of KEKB and (2) the comparison of beam-beam simulations with experiments at KEKB.

  13. Beam-beam issues in asymmetric colliders

    Energy Technology Data Exchange (ETDEWEB)

    Furman, M.A.

    1992-07-01

    We discuss generic beam-beam issues for proposed asymmetric e{sup +}- e{sup -} colliders. We illustrate the issues by choosing, as examples, the proposals by Cornell University (CESR-B), KEK, and SLAC/LBL/LLNL (PEP-II).

  14. Enlargement of Tuning Range in a Ferrite-Tuned Cavity Through Superposed Orthogonal and Parallel Magnetic Bias

    CERN Document Server

    Vollinger, C

    2013-01-01

    Conventional ferrite-tuned cavities operate either with bias fields that are orthogonal or parallel to the magnetic RF-field. For a cavity that tunes rapidly over an overall frequency range around 100-400 MHz with high Q, we use ferrite garnets exposed to an innovative new biasing method consisting of a superposition of perpendicular and parallel magnetic fields. This method leads to a significant enlargement of the high-Q cavity tuning range by defining an operation point close to the magnetic saturation and thus improving ferrite material behaviour. A further advantage of this technique is the fast tuning speed resulting from the fact that tuning is carried out either with pure parallel biasing, or together with a very small change of operating point from perpendicular bias. In this paper, several scaled test models of ferrite-filled resonators are shown; measurements on the set-ups are compared and discussed.

  15. Empirical model for controlling beam-beam effects in ISABELLE

    Energy Technology Data Exchange (ETDEWEB)

    Parzen, G

    1980-01-01

    The beam-beam interaction may limit the beam intensity in ISABELLE. Although considerable progress has been made in understanding the beam-beam interaction, there appears to be no reliable method at present for computing the effects of the beam-beam interaction. The steps taken at ISABELLE to limit beam-beam effects are based largely on the experience accumulated at the ISR. At the ISR, the beam-beam effects do not appear to be large, and the beam intensity at the ISR does not appear to be limited by beam-beam effects. The beam-beam effects may be much stronger in ISABELLE because of factors like higher intensity and stronger non-linearities.

  16. Strong-Strong Beam-Beam Simulation of Bunch Length Splitting at the LHC

    CERN Document Server

    Qiang, J; Pieloni, Tatiana; Ohmi, Kazuhito

    2015-01-01

    Longitudinal bunch length splitting was observed for some LHC beams. In this paper, we will report on the study of the observation using strong-strong beam-beam simulations. We explore a variety of factors including initial momentum deviation, collision crossing angle, synchrotron tune, chromaticity, working points and bunch intensity that contribute to the beam particle loss and the bunch length splitting, and try to understand the underlying mechanism of the observed phenomena.

  17. Beam-beam simulation code BBSIM for particle accelerators

    Energy Technology Data Exchange (ETDEWEB)

    Kim, Hyung J.; Sen, Tanaji; /Fermilab

    2011-01-01

    A highly efficient, fully parallelized, six-dimensional tracking model for simulating interactions of colliding hadron beams in high energy ring colliders and simulating schemes for mitigating their effects is described. The model uses the weak-strong approximation for calculating the head-on interactions when the test beam has lower intensity than the other beam, a look-up table for the efficient calculation of long-range beam-beam forces, and a self-consistent Poisson solver when both beams have comparable intensities. A performance test of the model in a parallel environment is presented. The code is used to calculate beam emittance and beam loss in the Tevatron at Fermilab and compared with measurements. They also present results from the studies of stwo schemes proposed to compensate the beam-beam interactions: (a) the compensation of long-range interactions in the Relativistic Heavy Ion Collider (RHIC) at Brookhaven and the Large Hadron Collider (LHC) at CERN with a current carrying wire, (b) the use of a low energy electron beam to compensate the head-on interactions in RHIC.

  18. Beam-beam simulation code BBSIM for particle accelerators

    Energy Technology Data Exchange (ETDEWEB)

    Kim, Hyung J.; Sen, Tanaji; /Fermilab

    2011-01-01

    A highly efficient, fully parallelized, six-dimensional tracking model for simulating interactions of colliding hadron beams in high energy ring colliders and simulating schemes for mitigating their effects is described. The model uses the weak-strong approximation for calculating the head-on interactions when the test beam has lower intensity than the other beam, a look-up table for the efficient calculation of long-range beam-beam forces, and a self-consistent Poisson solver when both beams have comparable intensities. A performance test of the model in a parallel environment is presented. The code is used to calculate beam emittance and beam loss in the Tevatron at Fermilab and compared with measurements. They also present results from the studies of stwo schemes proposed to compensate the beam-beam interactions: (a) the compensation of long-range interactions in the Relativistic Heavy Ion Collider (RHIC) at Brookhaven and the Large Hadron Collider (LHC) at CERN with a current carrying wire, (b) the use of a low energy electron beam to compensate the head-on interactions in RHIC.

  19. Simulation of Head-on Beam-Beam Limitations in Future High Energy Colliders

    CERN Document Server

    Buffat, Xavier; Florio, Adrien; Pieloni, Tatiana; Tambasco, Claudia

    2016-01-01

    The Future Circular Hadron Collider (FCC-hh) project calls for studies in a new regime of beam-beam interactions. While the emittance damping due to synchrotron radiation is still slower than in past or existing lepton colliders, it is significantly larger than in other hadron colliders. The slow reduction of the emittance is profitable for higher luminosity in term of transverse beam size at the interaction points and also to mitigate long-range beam-beam effects, potentially allowing for a reduction of the crossing angle between the beams during the operation. In such conditions, the strength of head-on beam-beam interactions increases, potentially limiting the beam brightness. 4D weak-strong and strong-strong simulations are performed in order to assess these limitations.

  20. MEMS variable capacitance devices utilizing the substrate: I. Novel devices with a customizable tuning range

    KAUST Repository

    Elshurafa, Amro M.

    2010-03-22

    This paper, the first in a series of two, presents a paradigm shift in the design of MEMS parallel plate PolyMUMPS variable capacitance devices by proposing two structures that utilize the substrate and are able to provide predetermined, customizable, tuning ranges and/or ratios. The proposed structures can provide theoretical tuning ranges anywhere from 4.9 to 35 and from 3.4 to 26 respectively with a simple, yet effective, layout modification as opposed to the previously reported devices where the tuning range is fixed and cannot be varied. Theoretical analysis is carried out and verified with measurements of fabricated devices. The first proposed device possessed initially a tuning range of 4.4. Two variations of the structure having tuning ranges of 3 and 3.4, all at 1 GHz, were also successfully developed and tested. The second proposed variable capacitance device behaved as a switch. © 2010 IOP Publishing Ltd.

  1. Simulation of Beam-Beam Background at CLIC

    CERN Document Server

    Sailer, A

    2010-01-01

    The dense beams used at CLIC to achieve a high luminosity will cause a large amount of background particles through beam-beam interactions. Generator level studies with GUINEAPIG and full detector simulation studies with an ILD based CLIC detector have been performed to evaluate the amount of beam-beam back- ground hitting the vertex detector.

  2. Tuning Range Optimization of a Planar Inverted F Antenna for LTE Low Frequency Bands

    DEFF Research Database (Denmark)

    Barrio, Samantha Caporal Del; Pelosi, Mauro; Franek, Ondrej

    2011-01-01

    This paper presents a Planar Inverted F Antenna (PIFA) tuned with a fixed capacitor to the low frequency bands supported by the Long Term Evolution (LTE) technology. The tuning range is investigated and optimized with respect to the bandwidth and the efficiency of the resulting antenna. Simulations...

  3. Tuning Range Optimization of a Planar Inverted F Antenna for LTE Low Frequency Bands

    DEFF Research Database (Denmark)

    Barrio, Samantha Caporal Del; Pelosi, Mauro; Franek, Ondrej

    2011-01-01

    This paper presents a Planar Inverted F Antenna (PIFA) tuned with a fixed capacitor to the low frequency bands supported by the Long Term Evolution (LTE) technology. The tuning range is investigated and optimized with respect to the bandwidth and the efficiency of the resulting antenna. Simulatio...... and mock-ups are presented....

  4. Linearizing Intra-Train Beam-Beam Deflection Feedback

    Energy Technology Data Exchange (ETDEWEB)

    Smith, S.R.; /SLAC

    2006-02-22

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

  5. Implementation of depolarization due to beam-beam effects in the beam-beam interaction simulation tool GUINEA-PIG++

    Science.gov (United States)

    Rimbault, C.; Le Meur, G.; Blampuy, F.; Bambade, P.; Schulte, D.

    2009-12-01

    Depolarization is a new feature in the beam-beam simulation tool GUINEA-PIG++ (GP++). The results of this simulation are studied and compared with another beam-beam simulation tool, CAIN, considering different beam parameters for the International Linear Collider (ILC) with a centre-of-mass energy of 500 GeV.

  6. Six-dimensional beam-beam kick including coupled motion

    Directory of Open Access Journals (Sweden)

    L. H. A. Leunissen

    2000-12-01

    Full Text Available The six-dimensional beam-beam interaction as developed in 1992 by Hirata, Moshammer, and Ruggiero has been extended to include linear coupled motion and an arbitrary crossing plane. The technique of symplectic mapping in the six-dimensional phase space, called synchrobeam mapping, is applied to investigate the beam-beam kick within a solenoid. A linear beam-beam model including coupling is discussed in detail, also in the framework of a six-dimensional symplectic dispersion formalism.

  7. Optimizing the electron beam parameters for head-on beam-beam compensation in RHIC

    Energy Technology Data Exchange (ETDEWEB)

    Luo, Y.; Fischer, W.; Pikin, A.; Gu, X.

    2011-03-28

    Head-on beam-beam compensation is adopted to compensate the large beam-beam tune spread from the protonproton interactions at IP6 and IP8 in the Relativistic Heavy Ion Collider (RHIC). Two e-lenses are being built and to be in stalled near IP10 in the end of 2011. In this article we perform numeric simulation to investigate the effect of the electron beam parameters on the proton dynamics. The electron beam parameters include its transverse profile, size, current, offset and random errors in them. In this article we studied the effect of the electron beam parameters on the proton dynamics. The electron beam parameters include its transverse shape, size, current, offset and their random errors. From the study, we require that the electron beam size can not be smaller than the proton beam's. And the random noise in the electron current should be better than 0.1%. The offset of electron beam w.r.t. the proton beam center is crucial to head-on beam-beam compensation. Its random errors should be below {+-}8{micro}m.

  8. Semiconductor lasers with a continuous tuning range above 100 nm in the nearest IR spectral region

    Energy Technology Data Exchange (ETDEWEB)

    Kostin, Yu O; Lobintsov, A A; Shramenko, M V [OOO ' Opton' , Moscow (Russian Federation); Ladugin, M A; Marmalyuk, A A [Open Joint-Stock Company M.F. Stel' makh Polyus Research Institute, Moscow (Russian Federation); Chamorovsky, A Yu [Superlum Ltd., Unit B3, Fota Point Enterprise Park, Carrigtwohill, Co Cork (Ireland); Yakubovich, S D [Moscow State Institute of Radio-Engineering, Electronics and Automation (Technical University), Moscow (Russian Federation)

    2015-08-31

    We have developed two new types of lasers based on quantum-confined semiconductor optical amplifiers with an acousto-optic tunable filter in an external fibre ring cavity. The lasers offer continuous wavelength tuning ranges from 780 to 885 and from 880 to 1010 nm, 20 mW of cw output power, and a tuning rate up to 10{sup 4} nm s{sup -1} at an instantaneous spectral linewidth less than 0.1 nm. (lasers)

  9. Beam-beam observations in the Relativistic Heavy Ion Collider

    Energy Technology Data Exchange (ETDEWEB)

    Luo, Y. [Brookhaven National Laboratory (BNL), Upton, NY (United States); Fischer, W. [Brookhaven National Laboratory (BNL), Upton, NY (United States); White, S. [Brookhaven National Laboratory (BNL), Upton, NY (United States)

    2015-06-24

    The Relativistic Heavy Ion Collider (RHIC) at Brookhaven National Laboratory has been operating since 2000. Over the past decade, thanks to the continuously increased bunch intensity and reduced β*s at the interaction points, the maximum peak luminosity in the polarized proton operation has been increased by more than two orders of magnitude. In this article, we first present the beam-beam observations in the previous RHIC polarized proton runs. Then we analyze the mechanisms for the beam loss and emittance growth in the presence of beam-beam interaction. The operational challenges and limitations imposed by beam-beam interaction and their remedies are also presented. In the end, we briefly introduce head-on beam-beam compensation with electron lenses in RHIC.

  10. Beam-beam effects under the influence of external noise

    CERN Document Server

    Ohmi, K.

    2014-01-01

    Fast external noise, which gives fluctuation into the beam orbit, is discussed in connection with beam-beam effects. Phase noise from crab cavities and detection devices (position monitor) and kicker noise from the bunch by bunch feedback system are the sources. Beam-beam collisions with fast orbit fluctuations with turn by turn or multi-turn correlations, cause emittance growth and luminosity degradation. We discuss the tolerance of the noise amplitude for LHC and HL-LHC.

  11. Coherent beam-beam effects observation and mitigation at the RHIC collider

    Energy Technology Data Exchange (ETDEWEB)

    White S.; Fischer, W.; Luo, Y.

    2012-05-20

    In polarized proton operation in RHIC coherent beam-beam modes are routinely observed with beam transfer function measurements in the vertical plane. With the existence of coherent modes a larger space is required in the tune diagram than without them and stable conditions can be compromised for operation with high intensity beams as foreseen for future luminosity upgrades. We report on experiments and simulations carried out to understand the existence of coherent modes in the vertical plane and their absence in the horizontal plane, and investigate possible mitigation strategies.

  12. A Wide Tuning-Range CMOS VCO with a Tunable Active Inductor

    Directory of Open Access Journals (Sweden)

    Hsuan-Ling Kao

    2015-01-01

    Full Text Available This study describes a wide tuning-range VCO using tunable active inductor (TAI topology and cross-coupled pair configuration for radio frequency operation. The TAI used two feedback loops to form a cascode circuit to obtain more degrees of freedom for inductance value. The TAI-VCO was fabricated using a 0.18 μm CMOS technology. The coarse frequency tuning is achieved by TAIs while the fine tuning is controlled by varactors. The fabricated circuit provides an output frequency range from 0.6 to 7.2 GHz (169%. The measured phase noise is from −110.38 to −86.01 dBc/Hz at a 1 MHz offset and output power is from −11.11 to −3.89 dBm within the entire frequency range under a 1.8 V power supply.

  13. MEMS-based LC tank with extended tuning range for multiband applications

    Science.gov (United States)

    Cazzorla, A.; Farinelli, P.; Urbani, L.; Sorrentino, R.; Margesin, B.

    2016-09-01

    This paper presents the modeling, simulations, and measurements of a compact multiband microelectromechanical (MEMS)-based LC tank resonator suitable for low phase noise voltage-controlled oscillators (VCOs). The resonator is based on a high-Q spiral inductor and high capacitance ratio varicap fully integrated in FBK-irst (Fondazione Bruno Kessler) MEMS manufacturing process. The design of the varicap is based on double-actuation mechanism with a mechanical central bond that inhibits the pull-in allowing for a theoretically infinite tuning ratio. The measurements have shown a total not continuous capacitance ratio (Cr) of 5.2 with a continuous variation of the capacitance values in the range 225 fF-600 fF which corresponds to a continuous capacitance ratio (Cr*) of 2.6. The performance repeatability, the power-handling capability, and the stability over time were tested on 10 samples showing a negligible variation of the capacitance values. The spiral inductor consists of a suspended gold membrane thick 5 µm in a circular shape which was modeled in order to optimize the quality factor (Q) in the frequency range 2-4 GHz. The measurement results show a Q of about 55 in the 2-4 GHz frequency band. The LC tank measurements show an overall tuning range better than of 45% in the 3.2-4.9 GHz frequency band, consisting of two continuous tuning ranges of 7.5% and 25%. The LC tank allowed the design of MEMS-based voltage-controlled oscillators (VCOs) with an overall tuning better than 60% in the frequency range 2.15 GHz-3.85 GHz and two separate regions of continuous tuning range. The VCO prototype will be fabricated on Surface Mount Technology on RO4350 laminate. The main figures of merit are presented in comparison with the state of the art.

  14. IC design of low power, wide tuning range VCO in 90 nm CMOS technology

    Science.gov (United States)

    Zhu, Li; Zhigong, Wang; Zhiqun, Li; Qin, Li; Faen, Liu

    2014-12-01

    A low power VCO with a wide tuning range and low phase noise has been designed and realized in a standard 90 nm CMOS technology. A newly proposed current-reuse cross-connected pair is utilized as a negative conductance generator to compensate the energy loss of the resonator. The supply current is reduced by half compared to that of the conventional LC-VCO. An improved inversion-mode MOSFET (IMOS) varactor is introduced to extend the capacitance tuning range from 32.8% to 66%. A detailed analysis of the proposed varactor is provided. The VCO achieves a tuning range of 27-32.5 GHz, exhibiting a frequency tuning range (FTR) of 18.4% and a phase noise of -101.38 dBc/Hz at 1 MHz offset from a 30 GHz carrier, and shows an excellent FOM of -185 dBc/Hz. With the voltage supply of 1.5 V, the core circuit of VCO draws only 2.1 mA DC current.

  15. A full free spectral range tuning of p-i-n doped Gallium Nitride microdisk cavity

    CERN Document Server

    Niu, Nan; Aharonovich, Igor; Russell, Kasey J; Woolf, Alexander; Sadler, Thomas C; El-Ella, Haitham A R; Kappers, Menno J; Oliver, Rachel A; Hu, Evelyn L

    2012-01-01

    Effective, permanent tuning of the whispering gallery modes (WGMs) of p-i-n doped GaN microdisk cavity with embedded InGaN quantum dots over one free spectral range is successfully demonstrated by irradiating the microdisks with a ultraviolet laser (380nm) in DI water. For incident laser powers between 150 and 960 nW, the tuning rate varies linearly. Etching of the top surface of the cavity is proposed as the driving force for the observed shift in WGMs, and is supported by experiments. The tuning for GaN/InGaN microdisk cavities is an important step for deterministically realizing novel nanophotonic devices for studying cavity quantum electrodynamics.

  16. Beam-beam studies for FCC-hh

    CERN Document Server

    Barranco Garcia, Javier; Buffat, Xavier; Furuseth, Sondre Vik

    2017-01-01

    The Future Circular Collider hadron-hadron (FCC-hh) design study is currently exploring different IR design possibilities including round and flat optics or different crossing schemes. The present study intends to evaluate each scenario from the beam-beam effects point of view. In particular the single particle long term stability to maximize beam lifetimes and luminosity reach is used to quantify the differences. The impact of strong head on interactions on the beam quality and lifetime is addressed by means of GPU accelerated simulations code featuring a weak-strong 6-dimensional beam-beam interaction.

  17. A grating-coupled external cavity InAs/InP quantum dot laser with 85-nm tuning range

    Science.gov (United States)

    Wei, Heng; Jin, Peng; Luo, Shuai; Ji, Hai-Ming; Yang, Tao; Li, Xin-Kun; Wu, Jian; An, Qi; Wu, Yan-Hua; Chen, Hong-Mei; Wang, Fei-Fei; Wu, Ju; Wang, Zhan-Guo

    2013-09-01

    The optical performance of a grating-coupled external cavity laser based on InAs/InP quantum dots is investigated. Continuous tuning from 1391 nm to 1468 nm is realized at an injection current of 1900 mA. With the injection current increasing to 2300 mA, the tuning is blue shifted to some extent to the range from 1383 nm to 1461 nm. By combining the effect of the injection current with the grating tuning, the total tuning bandwidth of the external cavity quantum-dot laser can reach up to 85 nm. The dependence of the threshold current on the tuning wavelength is also presented.

  18. Wide tuning-range CMOS VCO based on a tunable active inductor

    Science.gov (United States)

    Babaei Kia, Hojjat; Khari A'ain, Abu; Grout, Ian

    2014-01-01

    In this paper, a wide tuning-range CMOS voltage-controlled oscillator (VCO) with high output power using an active inductor circuit is presented. In this VCO design, the coarse frequency is achieved by tuning the integrated active inductor. The circuit has been simulated using a 0.18-µm CMOS fabrication process and presents output frequency range from 100 MHz to 2.5 GHz, resulting in a tuning range of 96%. The phase noise is -85 dBc/Hz at a 1 MHz frequency offset. The output power is from -3 dBm at 2.55 GHz to +14 dBm at 167 MHz. The active inductor power dissipation is 6.5 mW and the total power consumption is 16.27 mW when operating on a 1.8 V supply voltage. By comparing this active inductor architecture VCO with general VCO topology, the result shows that this topology, which employs the proposed active inductor, produces a better performance.

  19. Development of a Beam-Beam Simulation Code for e+e- Colliders

    CERN Document Server

    Zhang, Yuan

    2005-01-01

    BEPC will be upgraded into BEPCII, and the luminosity will be about 100 times higher. We developed a three dimensional strong-strong PIC code to study the beam-beam effects in BEPCII. The transportation through the arc is the same as that in Hirata's weak-strong code. The beam-beam force is computed directly by solving the Poisson equation using the FACR method, and the boundary potential is computed by circular convolution. The finite bunch length effect is included by longitudinal slices. An interpolation scheme is used to reduce the required slice number in simulations. The standard message passing interface (MPI) is used to parallelize the code. The computing time increases linearly with (n+1), where n is the slice number. The calculated luminosity of BEPCII at the design operating point is less than the design value. The best area in the tune space is near (0.505,0.57) according to the survey, where the degradation of luminosity can be improved.

  20. High-Accuracy Programmable Timing Generator with Wide-Range Tuning Capability

    Directory of Open Access Journals (Sweden)

    Ting-Li Chu

    2013-01-01

    Full Text Available In this paper, a high-accuracy programmable timing generator with wide-range tuning capability is proposed. With the aid of dual delay-locked loop (DLL, both of the coarse- and fine-tuning mechanisms are operated in precise closed-loop scheme to lessen the effects of the ambient variations. The timing generator can provide sub-gate resolution and instantaneous switching capability. The circuit is implemented and simulated in TSMC 0.18 μm 1P6M technology. The test chip area occupies 1.9 mm2. The reference clock cycle can be divided into 128 bins by interpolation to obtain 14 ps resolution with the clock rate at 550 MHz. The INL and DNL are within −0.21~+0.78 and −0.27~+0.43 LSB, respectively.

  1. A new nonempirical tuning scheme with single self-consistent field calculation: Comparison with global and IP-tuned range-separated functional.

    Science.gov (United States)

    Borpuzari, Manash Protim; Kar, Rahul

    2017-10-05

    System-dependent nonempirical tuning of range-separated functional provides a way to minimize the delocalization error of the system. However, existing nonempirical tuning method requires the computation of several ΔSCF calculations to determine the optimal μ value. In this article, we have defined a scheme to evaluate the optimal μ value with single self-consistent field calculation. Our method is based on the evaluation of the spherically symmetric average Electron localization function (ELF) region. According to this scheme, the radius of the spherically symmetric average ELF region gives is a measure of the distance at which the long-range part of the range-separated functional becomes dominant. Numerical results indicate that our method improves the reproduction of HOMO energies and HOMO-LUMO gap in comparison to global and IP-tuned range-separated functional. Moreover, in case of HOMO energies, maximum error of the ELF-tuned functional is considerably smaller than the global and IP-tuned functional. Furthermore, our method gives considerably smaller deviation of HOMO energies from ΔSCF IP than global range-separated functional. © 2017 Wiley Periodicals, Inc. © 2017 Wiley Periodicals, Inc.

  2. An electronically tuned wideband probehead for NQR spectroscopy in the VHF range

    Science.gov (United States)

    Scharfetter, Hermann

    2016-10-01

    Nuclear quadrupole resonance spectroscopy is an analytical method which allows to characterize materials which contain quadrupolar nuclei, i.e. nuclei with spin ⩾1. The measurement technology is similar to that of NMR except that no static magnetic field is necessary. In contrast to NMR, however, it is frequently necessary to scan spectra with a very large bandwidth with a span of several tens of % of the central frequency so as to localize unknown peaks. Standard NMR probeheads which are typically constructed as resonators must be tuned and matched to comparatively narrow bands and must thus be re-tuned and re-matched very frequently when scanning over a whole NQR spectrum. At low frequencies up to few MHz dedicated circuits without the need for tuning and matching have been developed, but many quadrupole nuclei have transitions in the VHF range between several tens of MHz up to several hundreds of MHz. Currently available commercial NQR probeheads employ stepper motors for setting mechanically tuneable capacitors in standard NMR resonators. These yield high quality factors (Q) and thus high SNR but are relatively large and clumsy and do not allow for fast frequency sweeps. This article presents a new concept for a NQR probehead which combines a previously published no-tune no-match wideband concept for the transmit (TX) pulse with an electronically tuneable receive (RX) part employing varactor diodes. The prototype coil provides a TX frequency range of 57 MHz with a center frequency of 97.5 MHz with a return loss of ⩽-15 dB. During RX the resonator is tuned and matched automatically to the right frequency via control voltages which are read out from a previously generated lookup table, thus providing high SNR. The control voltages which bias the varactors settle very fast and allow for hopping to the next frequency point in the spectrum within less than 100 μs. Experiments with a test sample of ZnBr2 proved the feasibility of the method.

  3. Beam-Beam Simulations with GUINEA-PIG

    CERN Document Server

    Schulte, Daniel

    1998-01-01

    While the bunches in a linear collider cross only once, due to their small size they experience a strong beam-beam effect. GUINEA-PIG is a code to simulate the impact of this effect on luminosity and back ground. A short overview of the program is given with examples of its application to the back ground strudies for TESLA, the top quark threshold scan and a possible luminosity monitor, as well as some results for CLIC.

  4. Observations and open questions in beam-beam interactions

    Energy Technology Data Exchange (ETDEWEB)

    Sen, Tanaji; /Fermilab

    2010-08-01

    The first of the hadron colliders, ISR, started operation in 1970. In the following years, the hadron colliders to follow were the SPS (started 1980), the Tevatron (started 1987 first as a fixed target machine), RHIC (started 2000) and most recently the LHC, which started in 2008. HERA was a hybrid that collided electrons and protons. All of these accelerators had or have their performance limited by the effects of the beam-beam interactions. That has also been true for the electron-positron colliders such as LEP, CESR, KEKB and PEPII. In this article I will discuss how the beam-beam limitations arose in some of these machines. The discussion will be focused on common themes that span the different colliders. I will mostly discuss the hadron colliders but sometimes discuss the lepton colliders where relevant. Only a handful of common accelerator physics topics are chosen here, the list is not meant to be exhaustive. A comparative review of beam-beam performance in the ISR, SPS and Tevatron (ca 1989) can be found in reference. Table 1 shows the relevant parameters of colliders (excluding the LHC), which have accelerated protons.

  5. Stochastic Optimally-Tuned Ranged-Separated Hybrid Density Functional Theory

    CERN Document Server

    Neuhauser, Daniel; Cytter, Yael; Baer, Roi

    2015-01-01

    We develop a stochastic formulation of the optimally-tuned range-separated hybrid density functional theory which enables significant reduction of the computational effort and scaling of the non-local exchange operator at the price of introducing a controllable statistical error. Our method is based on stochastic representations of the Coulomb convolution integral and of the generalized Kohn-Sham density matrix. The computational cost of the approach is similar to that of usual Kohn-Sham density functional theory, yet it provides much more accurate description of the quasiparticle energies for the frontier orbitals. This is illustrated for a series of silicon nanocrystals up to sizes exceeding 3000 electrons. Comparison with the stochastic GW many-body perturbation technique indicates excellent agreement for the fundamental band gap energies, good agreement for the band-edge quasiparticle excitations, and very low statistical errors in the total energy for large systems. The present approach has a major advan...

  6. Wide range tuning of resonant frequency for a vortex core in a regular triangle magnet.

    Science.gov (United States)

    Yakata, Satoshi; Tanaka, Terumitsu; Kiseki, Kohei; Matsuyama, Kimihide; Kimura, Takashi

    2013-12-20

    A magnetic vortex structure stabilized in a micron or nano-sized ferromagnetic disk has a strong potential as a unit cell for spin-based nano-electronic devices because of negligible magnetostatic interaction and superior thermal stability. Moreover, various intriguing fundamental physics such as bloch point reversal and symmetry breaking can be induced in the dynamical behaviors in the magnetic vortex. The static and dynamic properties of the magnetic vortex can be tuned by the disk dimension and/or the separation distance between the disks. However, to realize these modifications, the preparations of other devices with different sample geometries are required. Here, we experimentally demonstrate that, in a regular-triangle Permalloy dot, the dynamic properties of a magnetic vortex are greatly modified by the application of the in-plane magnetic field. The obtained wide range tunability based on the asymmetric position dependence of the core potential provides attractive performances in the microwave spintronic devices.

  7. Maximizing Sensory Dynamic Range by Tuning the Cortical State to Criticality.

    Directory of Open Access Journals (Sweden)

    Shree Hari Gautam

    2015-12-01

    Full Text Available Modulation of interactions among neurons can manifest as dramatic changes in the state of population dynamics in cerebral cortex. How such transitions in cortical state impact the information processing performed by cortical circuits is not clear. Here we performed experiments and computational modeling to determine how somatosensory dynamic range depends on cortical state. We used microelectrode arrays to record ongoing and whisker stimulus-evoked population spiking activity in somatosensory cortex of urethane anesthetized rats. We observed a continuum of different cortical states; at one extreme population activity exhibited small scale variability and was weakly correlated, the other extreme had large scale fluctuations and strong correlations. In experiments, shifts along the continuum often occurred naturally, without direct manipulation. In addition, in both the experiment and the model we directly tuned the cortical state by manipulating inhibitory synaptic interactions. Our principal finding was that somatosensory dynamic range was maximized in a specific cortical state, called criticality, near the tipping point midway between the ends of the continuum. The optimal cortical state was uniquely characterized by scale-free ongoing population dynamics and moderate correlations, in line with theoretical predictions about criticality. However, to reproduce our experimental findings, we found that existing theory required modifications which account for activity-dependent depression. In conclusion, our experiments indicate that in vivo sensory dynamic range is maximized near criticality and our model revealed an unanticipated role for activity-dependent depression in this basic principle of cortical function.

  8. Maximizing Sensory Dynamic Range by Tuning the Cortical State to Criticality

    Science.gov (United States)

    Gautam, Shree Hari; Hoang, Thanh T.; McClanahan, Kylie; Grady, Stephen K.; Shew, Woodrow L.

    2015-01-01

    Modulation of interactions among neurons can manifest as dramatic changes in the state of population dynamics in cerebral cortex. How such transitions in cortical state impact the information processing performed by cortical circuits is not clear. Here we performed experiments and computational modeling to determine how somatosensory dynamic range depends on cortical state. We used microelectrode arrays to record ongoing and whisker stimulus-evoked population spiking activity in somatosensory cortex of urethane anesthetized rats. We observed a continuum of different cortical states; at one extreme population activity exhibited small scale variability and was weakly correlated, the other extreme had large scale fluctuations and strong correlations. In experiments, shifts along the continuum often occurred naturally, without direct manipulation. In addition, in both the experiment and the model we directly tuned the cortical state by manipulating inhibitory synaptic interactions. Our principal finding was that somatosensory dynamic range was maximized in a specific cortical state, called criticality, near the tipping point midway between the ends of the continuum. The optimal cortical state was uniquely characterized by scale-free ongoing population dynamics and moderate correlations, in line with theoretical predictions about criticality. However, to reproduce our experimental findings, we found that existing theory required modifications which account for activity-dependent depression. In conclusion, our experiments indicate that in vivo sensory dynamic range is maximized near criticality and our model revealed an unanticipated role for activity-dependent depression in this basic principle of cortical function. PMID:26623645

  9. Report of the group on beam-beam effects in circular colliders

    Energy Technology Data Exchange (ETDEWEB)

    Furman, M.A.

    1991-05-01

    We present a summary of the discussions and conclusions of the working group on beam-beam effects for circular colliders. This group was part of the larger beam-beam dynamics group at the 7th ICFA Workshop on Beam Dynamics, on the subject Beam-Beam and Beam-Radiation Interactions,'' held at UCLA, May 13--16, 1991. 15 refs.

  10. Experimental observations and theoretical models for beam-beam phenomena

    Energy Technology Data Exchange (ETDEWEB)

    Kheifets, S.

    1981-03-01

    The beam-beam interaction in storage rings exhibits all the characteristics of nonintegrable dynamical systems. Here one finds all kinds of resonances, closed orbits, stable and unstable fixed points, stochastic layers, chaotic behavior, diffusion, etc. The storage ring itself being an expensive device nevertheless while constructed and put into operation presents a good opportunity of experimentally studying the long-time behavior of both conservative (proton machines) and nonconservative (electron machines) dynamical systems - the number of bunch-bunch interactions routinely reaches values of 10/sup 10/-10/sup 11/ and could be increased by decreasing the beam current. At the same time the beam-beam interaction puts practical limits for the yield of the storage ring. This phenomenon not only determines the design value of main storage ring parameters (luminosity, space charge parameters, beam current), but also in fact prevents many of the existing storage rings from achieving design parameters. Hence, the problem has great practical importance along with its enormous theoretical interest. A brief overview of the problem is presented.

  11. Non-Empirically Tuned Range-Separated DFT Accurately Predicts Both Fundamental and Excitation Gaps in DNA and RNA Nucleobases

    CERN Document Server

    Foster, Michael E; 10.1021/ct300420f

    2012-01-01

    Using a non-empirically tuned range-separated DFT approach, we study both the quasiparticle properties (HOMO-LUMO fundamental gaps) and excitation energies of DNA and RNA nucleobases (adenine, thymine, cytosine, guanine, and uracil). Our calculations demonstrate that a physically-motivated, first-principles tuned DFT approach accurately reproduces results from both experimental benchmarks and more computationally intensive techniques such as many-body GW theory. Furthermore, in the same set of nucleobases, we show that the non-empirical range-separated procedure also leads to significantly improved results for excitation energies compared to conventional DFT methods. The present results emphasize the importance of a non-empirically tuned range-separation approach for accurately predicting both fundamental and excitation gaps in DNA and RNA nucleobases.

  12. Tuning the Polarization State of Light over a Broad Frequency Range with Metasurfaces

    Science.gov (United States)

    Wang, Mu; Jiang, Shang-Chi; Wang, Zheng-Han; Xiong, Xiang; Peng, Ru-Wen; Nanjing University Team

    Controlling the polarization state, the transmission direction and the phase of light within a confined space is an important issue in optics. By integrating metallic metastructure and dielectric interlayer, it is possible to realize the dispersion-free broadband device on sub-wavelength scale, where the strong response of the metallic structures helps to decrease the device size while the dielectric interlayer helps to eliminate the dispersion simultaneously in both the amplitude and the phase difference of the reflected/transmitted light. As an examples to apply this concept, a broadband quarter-wave plate and a half-wave plate are experimentally demonstrated. By carefully selecting the structural parameters, the polarization state of light can be freely tuned across a broad frequency range, and all of the polarization states on the Poincaré sphere can be realized dispersion free. Some contents of this talk can be found in the following references: [1] S.-C. Jiang, et al., High-efficiency generation of circularly polarized light via symmetry-induced anomalous reflection,Physical Review B 91, 125421 (2015), [2] S.-C. Jiang, et al., Controlling the Polarization State of Light with a Dispersion-Free Metastructure, Physical Review X 4, 021026 (2014), [3] X. Xiong, et al., Metallic stereostructured layer: an approach for broadband polarization state manipulation,Applied Physics Letters 105, 201105 (2014).

  13. Novel Cross-Type Network for Wide-Tuning-Range Reconfigurable Multiband Antennas

    Directory of Open Access Journals (Sweden)

    Chieh-Sen Lee

    2014-01-01

    Full Text Available This paper presents a cross-type network design with a novel reconfigurable functionality to realize a tunable multiband antenna. By attaching a reconfigurable network at the feeding port of a broadband antenna, multi-input impedance adjustment enables the production of multimatching operating bands. Each band can be independently controlled by a single component with a considerably wide tuning range and high selectivity. The experiments in this study involved using an ultra-wideband (UWB antenna connected to the proposed cross-type network. The tunable antenna operates in a dual band of fL (1.39 to 2.34 GHz and fH (2.1 to 3.6 GHz with tunable frequency ratios of 168% and 132%, respectively. The average bandwidths at fL and fH are approximately 50 MHz and 148 MHz, respectively, implying narrowband operation. The measured radiation pattern revealed that the tunable antenna exhibits a nearly omnidirectional radiation pattern at both 1.8 and 3.5 GHz. The network circuit architecture can be extended to the multiband function type by adopting this matching approach. The amount of shunt matches determines the number of operation bands.

  14. Beam-Beam Effect with an External Noise in LHC

    CERN Document Server

    Ohmi, K; Höfle, Wolfgang; Tomás, R; Zimmermann, F

    2007-01-01

    In absence of synchrotron radiation, proton beams do not have any damping mechanism for incoherent betatron motion. A noise, which kicks beam particles in the transverse plane, gives a coherent betatron amplitude. If the system is linear, the coherent motion is maintained in amplitude. Nonlinear force, beam-beam and beam-electron cloud interactions, cause a decoherence of the betatron motion keeping the amplitude of each beam particle, with the result that an emittance growth arises. We focus only on fast noise with a correlation time of 1-100 turns. Slower noise is less serious, because it is regarded as an adiabatic change like a closed orbit change. As sources of the noise, we consider the bunch by bunch feedback system and phase jitter of cavities which turns to transverse noise via a crab cavity.

  15. Beam-Beam Effects in the Ring-Ring Version of eRHIC

    CERN Document Server

    Shi, Jack; Wang, Dong; Wang, Fuhua

    2005-01-01

    The eRHIC is a proposed electron ring at the RHIC that will provide collisions between a polarized 5-10 GeV electron beam and an ion beam from one of the RHIC rings. In order to achieve proposed high luminosity, large bunch current and small beta-functions at the IP has to be employed. Such measures result in large beam-beam parameters, 0.029 and 0.08 for the electron beam and 0.0065 and 0.0033 for the proton beam in the horizontal and vertical plane, respectively, in the current ZDR design. The beam-beam effect especially the coherent beam-beam effect is therefore one of important issues to the eRHIC. Moreover, the proposed configuration of unequal circumferences of the electron and proton rings could further enhance the coherent beam-beam effect. The beam-beam effect of eRHIC has therefore been studied with a self-consistent beam-beam simulation by using the particle-in-cell method. Beam-beam limits of the electron and proton beam were examined as thresholds of the onset of coherent beam-beam instability. F...

  16. Low-Voltage, Low-Power, and Wide-Tuning-Range Ring-VCO for Frequency ΔΣ Modulator

    DEFF Research Database (Denmark)

    Tuan Vu, Cao; Wisland, Dag T.; Lande, Tor Sverre

    A low-voltage, low-power, and wide-tuning-range VCO which converts an analog input voltage to phase information for a frequency ΔΣ modulator is proposed in this paper. The VCO is based on a differential ring oscillator, which is improved with modified symmetric load and a positive feedback in the...

  17. A fully integrated W-band push-push CMOS VCO with low phase noise and wide tuning range.

    Science.gov (United States)

    Wang, To-Po

    2011-07-01

    A circuit topology suitable for a low-phase-noise wide-tuning-range push-push voltage-controlled oscillator (VCO) is proposed in this paper. By applying varactors connected between drain and source terminations of the cross-coupled pair, the tuning range is effectively increased and the phase noise is improved. Moreover, a small capacitor is inserted between the VCO core and testing buffer to reduce loading effects on the VCO core. Furthermore, the enhanced second-harmonic output signal is extracted at middle of the varactors, leading to the elimination of RF choke at VCO's second-harmonic output port and a reduced chip size. Based on the proposed architecture, this VCO fabricated in 0.18-μm CMOS exhibits a measured 6.35% tuning range. Operating at a supply voltage of 1.2 V, the VCO core consumes 7.5-mW dc power, and the measured phase noise is -75 dBc/Hz and -91.5 dBc/Hz at 100-kHz and 1-MHz offsets from the 77.8-GHz carrier, respectively. Compared with previously published silicon-based VCOs over 70 GHz, this work can simultaneously achieve low phase noise, wide tuning range, and low dc power consumption, leading to a superior figure of merit (FOM), and better figure of merit considering the tuning range (FOM(T)). In addition, this fully integrated VCO also demonstrates the highest operation frequency among previously published 0.18-μm CMOS VCOs.

  18. Sampled grating tunable twin-guide laser diodes with wide tuning range (40 nm) and large output power (10 mW)

    Science.gov (United States)

    Todt, R.; Jacke, T.; Meyer, R.; Adler, J.; Laroy, R.; Morthier, G.; Amann, M.-C.

    2006-03-01

    The sampled grating tunable twin-guide (SG-TTG) laser diode is a DFB-like tunable laser that employs Vernier-effect tuning to achieve wide wavelength tuning. In contrast to most other monolithic widely tunable lasers (which are usually DBR-type lasers), a phase tuning section is not needed and, hence, the SG-TTG laser requires at least one tuning current less than comparable devices.The devices provide full wavelength coverage over a 40 nm-broad tuning range that is centered at 1.54 μm. Its tuning behavior is quasi-continuous with up to 8.2 nm broad continuous tuning regions. High side-mode suppression (SMSR 35 dB) as well as large output power (P 10 mW) are obtained over the whole wavelength range from 1520.5 to 1561.5 nm.

  19. A new model for the collective beam-beam interaction

    Energy Technology Data Exchange (ETDEWEB)

    Ellison, J.A.; Sobol, A.V. [New Mexico Univ., Albuquerque, NM (United States); Vogt, M. [Deutsches Elektronen-Synchrotron (DESY), Hamburg (Germany)

    2006-09-15

    The Collective Beam-Beam interaction is studied in the framework of maps with a ''kick-lattice'' model in 4-D phase space. A novel approach to the classical method of averaging is used to derive an approximate map which is equivalent to a flow within the averaging approximation. The flow equation is a continuous-time Vlasov equation which we call the averaged Vlasov equation, the new model of this paper. The power of this approach is evidenced by the fact that the averaged Vlasov equation has exact equilibria and the associated lineralized equations have uncoupled azimuthal Fourier modes. The equation for the Fourier modes leads to a Fredholm integral equation of the third kind and the setting is ready-made for the development of a weakly nonlinear theory to study the coupling of the {pi} and {sigma} modes. The {pi} and {sigma} modes are calculated from the third kind integral equation and results are compared with the kick-lattice model. (orig.)

  20. Theory, design, and performance of extended tuning range semiconductor lasers with sampled gratings

    Energy Technology Data Exchange (ETDEWEB)

    Jayaraman, V.; Chuang, Zuon-Min; Coldren, L.A. (Univ. of California, Santa Barbara, CA (United States))

    1993-06-01

    The authors have recently demonstrated 57 nm of tuning in a monolithic semiconductor laser using conventional DBR technology with grating elements removed in a periodic fashion. This paper describes the theory and design of these sampled grating tunable lasers. They first calculate sampled grating reflectivity. They then present normalized design curves which quantify tradeoffs involved in a sampled grating DBR laser with two mismatched sampled grating mirrors. These results are applied to design example in the InP-InGaAsP system. The design example provides 70 nm tuning wile maintaining [gt]30 dB MSR, with fractional index change [Delta][mu]/[mu] [lt] 0.2% in the mirrors, and only 1 mm of total sampled grating length. Section 4 summarizes recent experimental results, and compares them to theory. They also analyze other device structures which make use of sampled gratings.

  1. Low-Voltage, Low-Power, and Wide-Tuning-Range Ring-VCO for Frequency ΔΣ Modulator

    DEFF Research Database (Denmark)

    Tuan Vu, Cao; Wisland, Dag T.; Lande, Tor Sverre

    A low-voltage, low-power, and wide-tuning-range VCO which converts an analog input voltage to phase information for a frequency ΔΣ modulator is proposed in this paper. The VCO is based on a differential ring oscillator, which is improved with modified symmetric load and a positive feedback...... in the differential delay cells, a new bias circuit and a full-swing amplifier. The proposed VCO operating with two stages at a power supply voltage of 0.6 V can achieve wide tuning-range and low power consumption of 176.892 uW. The new VCO has a good linearity reducing harmonic distortion for frequency ΔΣ modulator...

  2. A tuning fork based wide range mechanical characterization tool with nanorobotic manipulators inside a scanning electron microscope

    Energy Technology Data Exchange (ETDEWEB)

    Acosta, Juan Camilo; Hwang, Gilgueng; Regnier, Stephane [Institut des Systemes Intelligents et de Robotique Universite Pierre et Marie Curie, CNRS UMR 7222 4 Place Jussieu, 75252 Paris Cedex (France); Polesel-Maris, Jerome [CEA, IRAMIS, Service de Physique et Chimie des Surfaces et Interfaces, F-91191 Gif-sur-Yvette (France)

    2011-03-15

    This study proposes a tuning fork probe based nanomanipulation robotic system for mechanical characterization of ultraflexible nanostructures under scanning electron microscope. The force gradient is measured via the frequency modulation of a quartz tuning fork and two nanomanipulators are used for manipulation of the nanostructures. Two techniques are proposed for attaching the nanostructure to the tip of the tuning fork probe. The first technique involves gluing the nanostructure for full range characterization whereas the second technique uses van der Waals and electrostatic forces in order to avoid destroying the nanostructure. Helical nanobelts (HNB) are proposed for the demonstration of the setup. The nonlinear stiffness behavior of HNBs during their full range tensile studies is clearly revealed for the first time. Using the first technique, this was between 0.009 N/m for rest position and 0.297 N/m before breaking of the HNB with a resolution of 0.0031 N/m. For the second experiment, this was between 0.014 N/m for rest position and 0.378 N/m before detaching of the HNB with a resolution of 0.0006 N/m. This shows the wide range sensing of the system for potential applications in mechanical property characterization of ultraflexible nanostructures.

  3. Beam-Beam Scans Within a Linear Collider Bunch-Train Crossing

    Energy Technology Data Exchange (ETDEWEB)

    Smith, S.R.; /SLAC

    2006-02-22

    Beam-beam deflection scans provide important beam diagnostics at the interaction point of a linear collider. Beam properties such as spot sizes, alignment, and waists are measured by sweeping one beam across the other. Proposed linear colliders use trains of bunches; if beam-beam scans can be done within the time of a bunch-train crossing rather than integrating over the bunch train, the acquisition rate of diagnostic information can be increased and the sensitivity of the scan to pulse-to-pulse jitter and slow drifts reduced. The existence of intra-train deflection feedback provides most of the hardware needed to implement intra-train beam-beam scans for diagnostic purposes. A conceptual design is presented for such beam-beam scans at the Next Linear Collider (NLC).

  4. Lattice design for head-on beam-beam compensation at RHIC

    Energy Technology Data Exchange (ETDEWEB)

    Montag, C.

    2011-03-28

    Electron lenses for head-on beam-beam compensation will be installed in IP 10 at RHIC. Compensation of the beam-beam effect experienced at IP 8 requires betatron phase advances of {Delta}{psi} = k {center_dot} {pi} between the proton-proton interaction point at IP 8, and the electron lens at IP 10. This paper describes the lattice solutions for both the BLUE and the YELLOW ring to achieve this goal.

  5. Simulations of coherent beam-beam effects with head-on compensation

    Energy Technology Data Exchange (ETDEWEB)

    White S.; Fischer, W.; Luo. Y.

    2012-05-20

    Electron lenses are under construction for installation in RHIC in order to mitigate the head-on beam-beam effects. This would allow operation with higher bunch intensity and result in a significant increase in luminosity. We report on recent strong-strong simulations and experiments that were carried out using the RHIC upgrade parameters to assess the impact of coherent beam-beam effects in the presence of head-on compensation.

  6. Development of 3D beam-beam simulation for the Tevatron

    Energy Technology Data Exchange (ETDEWEB)

    Stern, E.; Amundson, J.; Spentzouris, P.; Valishev, A.; /Fermilab; Qiang, J.; Ryne, R.; /LBL, Berkeley

    2007-06-01

    We present status of development of a 3D Beam-Beam simulation code for simulating the Fermilab Tevatron collider. The essential features of the code are 3D particle-in-cell Poisson solver for calculating the Beam-Beam electromagnetic interactions with additional modules for linear optics, machine impedance and chromaticity, and multiple bunch tracking. The simulations match synchrobetatron oscillations measured at the VEPP-2M collider. The impedance calculations show beam instability development consistent with analytic expressions.

  7. Impact of beam-beam effects on precision luminosity measurements at the ILC

    CERN Document Server

    Rimbault, C; Mönig, K; Schulte, D

    2007-01-01

    In this paper, the impact of beam-beam effects on the precision luminosity measurement at the International Linear Collider is investigated quantitatively for the first time. GUINEA-PIG, a beam-beam interaction simulation tool, is adapted to treat the space charge effects affecting the Bhabha events used in this measurement. The biases due to the resulting changes in kinematics are evaluated for different center-of-mass energies and beam parameters.

  8. Status of head-on beam-beam compensation in RHIC

    CERN Document Server

    Fischer, W; Anerella, M; Blaskiewicz, M; Bruno, D; Costanzo, M; Dawson, W C; Gassner, D M; Gu, X; Gupta, R C; Hamdi, K; Hock, J; Hoff, L T; Hulsart, R; Jain, A K; Lambiase, R; Luo, Y; Mapes, M; Marone, A; Michnoff, R; Miller, T A; Minty, M; Montag, C; Muratore, J; Nemesure, S; Phillips, D; Pikin, A I; Plate, S R; Rosas, P; Snydstrup, L; Tan, Y; Theisen, C; Thieberger, P; Tuozzolo, J; Wanderer, P; White, S M; Zhang, W

    2014-01-01

    In polarized proton operation, the performance of the Relativistic Heavy Ion Collider (RHIC) is limited by the head-on beam-beam effect. To overcome this limitation, two electron lenses are under commissioning. We give an overview of head-on beam-beam compensation in general and in the specific design for RHIC, which is based on electron lenses. The status of installation and commissioning are presented along with plans for the future.

  9. Angle-dependent strong-field molecular ionization rates with tuned range-separated time-dependent density functional theory.

    Science.gov (United States)

    Sissay, Adonay; Abanador, Paul; Mauger, François; Gaarde, Mette; Schafer, Kenneth J; Lopata, Kenneth

    2016-09-07

    Strong-field ionization and the resulting electronic dynamics are important for a range of processes such as high harmonic generation, photodamage, charge resonance enhanced ionization, and ionization-triggered charge migration. Modeling ionization dynamics in molecular systems from first-principles can be challenging due to the large spatial extent of the wavefunction which stresses the accuracy of basis sets, and the intense fields which require non-perturbative time-dependent electronic structure methods. In this paper, we develop a time-dependent density functional theory approach which uses a Gaussian-type orbital (GTO) basis set to capture strong-field ionization rates and dynamics in atoms and small molecules. This involves propagating the electronic density matrix in time with a time-dependent laser potential and a spatial non-Hermitian complex absorbing potential which is projected onto an atom-centered basis set to remove ionized charge from the simulation. For the density functional theory (DFT) functional we use a tuned range-separated functional LC-PBE*, which has the correct asymptotic 1/r form of the potential and a reduced delocalization error compared to traditional DFT functionals. Ionization rates are computed for hydrogen, molecular nitrogen, and iodoacetylene under various field frequencies, intensities, and polarizations (angle-dependent ionization), and the results are shown to quantitatively agree with time-dependent Schrödinger equation and strong-field approximation calculations. This tuned DFT with GTO method opens the door to predictive all-electron time-dependent density functional theory simulations of ionization and ionization-triggered dynamics in molecular systems using tuned range-separated hybrid functionals.

  10. Angle-dependent strong-field molecular ionization rates with tuned range-separated time-dependent density functional theory

    Science.gov (United States)

    Sissay, Adonay; Abanador, Paul; Mauger, François; Gaarde, Mette; Schafer, Kenneth J.; Lopata, Kenneth

    2016-09-01

    Strong-field ionization and the resulting electronic dynamics are important for a range of processes such as high harmonic generation, photodamage, charge resonance enhanced ionization, and ionization-triggered charge migration. Modeling ionization dynamics in molecular systems from first-principles can be challenging due to the large spatial extent of the wavefunction which stresses the accuracy of basis sets, and the intense fields which require non-perturbative time-dependent electronic structure methods. In this paper, we develop a time-dependent density functional theory approach which uses a Gaussian-type orbital (GTO) basis set to capture strong-field ionization rates and dynamics in atoms and small molecules. This involves propagating the electronic density matrix in time with a time-dependent laser potential and a spatial non-Hermitian complex absorbing potential which is projected onto an atom-centered basis set to remove ionized charge from the simulation. For the density functional theory (DFT) functional we use a tuned range-separated functional LC-PBE*, which has the correct asymptotic 1/r form of the potential and a reduced delocalization error compared to traditional DFT functionals. Ionization rates are computed for hydrogen, molecular nitrogen, and iodoacetylene under various field frequencies, intensities, and polarizations (angle-dependent ionization), and the results are shown to quantitatively agree with time-dependent Schrödinger equation and strong-field approximation calculations. This tuned DFT with GTO method opens the door to predictive all-electron time-dependent density functional theory simulations of ionization and ionization-triggered dynamics in molecular systems using tuned range-separated hybrid functionals.

  11. Energy level alignment at molecule-metal interfaces from an optimally tuned range-separated hybrid functional

    Science.gov (United States)

    Liu, Zhen-Fei; Egger, David A.; Refaely-Abramson, Sivan; Kronik, Leeor; Neaton, Jeffrey B.

    2017-03-01

    The alignment of the frontier orbital energies of an adsorbed molecule with the substrate Fermi level at metal-organic interfaces is a fundamental observable of significant practical importance in nanoscience and beyond. Typical density functional theory calculations, especially those using local and semi-local functionals, often underestimate level alignment leading to inaccurate electronic structure and charge transport properties. In this work, we develop a new fully self-consistent predictive scheme to accurately compute level alignment at certain classes of complex heterogeneous molecule-metal interfaces based on optimally tuned range-separated hybrid functionals. Starting from a highly accurate description of the gas-phase electronic structure, our method by construction captures important nonlocal surface polarization effects via tuning of the long-range screened exchange in a range-separated hybrid in a non-empirical and system-specific manner. We implement this functional in a plane-wave code and apply it to several physisorbed and chemisorbed molecule-metal interface systems. Our results are in quantitative agreement with experiments, the both the level alignment and work function changes. Our approach constitutes a new practical scheme for accurate and efficient calculations of the electronic structure of molecule-metal interfaces.

  12. A no-tune no-match wideband probe for nuclear quadrupole resonance spectroscopy in the VHF range

    Science.gov (United States)

    Scharfetter, Hermann; Petrovic, Andreas; Eggenhofer, Heidi; Stollberger, Rudolf

    2014-12-01

    Nuclear quadrupole resonance (NQR) spectroscopy is a method for the characterization of chemical compounds containing so-called quadrupolar nuclei. Similar to nuclear magnetic resonance (NMR), the sample under investigation is irradiated with strong radiofrequency (RF) pulses, which stimulate the emission of weak RF signals from the quadrupolar nuclei. The signals are then amplified and Fourier transformed so as to obtain a spectrum. In principle, narrowband NQR spectra can be measured with NMR spectrometers. However, pure NQR signals require the absence of a static magnetic field and several special applications require the characterization of a substance over a large bandwidth, e.g. 50-100% of the central frequency, which is hardly possible with standard NMR equipment. Dedicated zero-field NQR equipment is not widespread and current concepts employ resonating probes which are tuned and matched over a wide range by using mechanical capacitors driven by stepper motors. While providing the highest signal to noise ratio (SNR) such probes are slow in operation and can only be operated from dedicated NMR consoles. We developed a low-cost NQR wideband probe without tuning and matching for applications in the very high frequency (VHF) range below 300 MHz. The probe coil was realized as part of a reactive network which approximates an exponential transmission line. The input reflection coefficient of the two developed prototype probe coils is ≤ 20 dB between 90-145 MHz and 74.5-99.5 MHz, respectively. Two wideband NQR spectra of published test substances were acquired with an SNR of better than 20 dB after sufficient averaging. The measured signals and the SNR correspond very well to the theoretically expected values and demonstrate the feasibility of the method. Because there is no need for tuning and matching, our probes can be operated easily from any available NMR console.

  13. A-189 dBc/Hz FoMT Wide Tuning Range VCO Using Q-Factor Enhancement Technique

    Science.gov (United States)

    Liu, Faen; Wang, Zhigong; Li, Zhiqun; Li, Qin; Wang, Rong; Yang, Geliang; Li, Zhu

    2015-06-01

    A 28-GHz voltage-controlled oscillator (VCO) with a wide tuning range and a low phase noise is presented in this paper. A PMOS-only cross-coupled pair with a lower flicker noise is exploited to provide the negative resistance. The mechanisms for enhancing the Q-factor of the LC tank at millimeter-wave (mm-wave) frequencies are analyzed and applied to optimize the proposed VCO design to obtain a low phase noise. To guarantee accurate oscillating frequencies, distributed interconnections are carefully modeled by EM simulations. Fabricated in a standard 90-nm CMOS process, the proposed VCO achieves a wide tuning range of 20.1 %, from 25 to 30.66 GHz and a low phase noise of -105.47 dBc/Hz at 1-MHz offset. The current of the core circuit is 10.5 mA under a single 1.2-V supply. The core area of the chip is 0.38 mm × 0.24 mm.

  14. Reversible Halide Exchange Reaction of Organometal Trihalide Perovskite Colloidal Nanocrystals for Full-Range Band Gap Tuning.

    Science.gov (United States)

    Jang, Dong Myung; Park, Kidong; Kim, Duk Hwan; Park, Jeunghee; Shojaei, Fazel; Kang, Hong Seok; Ahn, Jae-Pyung; Lee, Jong Woon; Song, Jae Kyu

    2015-08-12

    In recent years, methylammonium lead halide (MAPbX3, where X = Cl, Br, and I) perovskites have attracted tremendous interest caused by their outstanding photovoltaic performance. Mixed halides have been frequently used as the active layer of solar cells, as a result of their superior physical properties as compared to those of traditionally used pure iodide. Herein, we report a remarkable finding of reversible halide-exchange reactions of MAPbX3, which facilitates the synthesis of a series of mixed halide perovskites. We synthesized MAPbBr3 plate-type nanocrystals (NCs) as a starting material by a novel solution reaction using octylamine as the capping ligand. The synthesis of MAPbBr(3-x)Clx and MAPbBr(3-x)Ix NCs was achieved by the halide exchange reaction of MAPbBr3 with MACl and MAI, respectively, in an isopropyl alcohol solution, demonstrating full-range band gap tuning over a wide range (1.6-3 eV). Moreover, photodetectors were fabricated using these composition-tuned NCs; a strong correlation was observed between the photocurrent and photoluminescence decay time. Among the two mixed halide perovskite series, those with I-rich composition (x = 2), where a sole tetragonal phase exists without the incorporation of a cubic phase, exhibited the highest photoconversion efficiency. To understand the composition-dependent photoconversion efficiency, first-principles density-functional theory calculations were carried out, which predicted many plausible configurations for cubic and tetragonal phase mixed halides.

  15. Tuning Range-Separated Density Functional Theory for Photocatalytic Water Splitting Systems

    CERN Document Server

    Bokareva, Olga S; Bokarev, Sergey I; Kühn, Oliver

    2015-01-01

    We discuss the applicability of long-range separated density functional theory (DFT) to the prediction of electronic transitions of a particular photocatalytic system based on an Ir(III) photosensitizer (IrPS). Special attention is paid to the charge-transfer properties which are of key importance for the photoexcitation dynamics, but and cannot be correctly described by means of conventional DFT. The optimization of the range-separation parameter is discussed for IrPS including its complexes with electron donors and acceptors used in photocatalysis. Particular attention is paid to the problems arising for a description of medium effects by a polarizable continuum model.

  16. 47.8 GHz InPHBT quadrature VCO with 22% tuning range

    DEFF Research Database (Denmark)

    Hadziabdic, Dzenan; Johansen, Tom Keinicke; Krozer, Viktor;

    2007-01-01

    A 38-47.8 GHz quadrature voltage controlled oscillator (QVCO) in InP HBT technology is presented. The measured output power is - 15 dBm. The simulated phase noise ranges from -84 to -86 dBc/Hz at 1 MHz offset. It is believed that this is the first millimetre-wavc QVCO implemented in InP HBT techn...

  17. Analog VLSI Models of Range-Tuned Neurons in the Bat Echolocation System

    Directory of Open Access Journals (Sweden)

    Horiuchi Timothy

    2003-01-01

    Full Text Available Bat echolocation is a fascinating topic of research for both neuroscientists and engineers, due to the complex and extremely time-constrained nature of the problem and its potential for application to engineered systems. In the bat's brainstem and midbrain exist neural circuits that are sensitive to the specific difference in time between the outgoing sonar vocalization and the returning echo. While some of the details of the neural mechanisms are known to be species-specific, a basic model of reafference-triggered, postinhibitory rebound timing is reasonably well supported by available data. We have designed low-power, analog VLSI circuits to mimic this mechanism and have demonstrated range-dependent outputs for use in a real-time sonar system. These circuits are being used to implement range-dependent vocalization amplitude, vocalization rate, and closest target isolation.

  18. Tuning of photoreceptor function in three mantis shrimp species that inhabit a range of depths. II. Filter pigments.

    Science.gov (United States)

    Cronin, Thomas W; Caldwell, Roy L

    2002-04-01

    Within single species of stomatopod crustaceans, visual pigment classes of homologous photoreceptors throughout the retina are identical in all individuals and do not vary with the spectral characteristics of local habitats. We examined whether spectral sensitivities of stomatopod photoreceptors are differentially tuned through variations in the filter pigments associated with particular receptor classes. All classes of intrarhabdomal filters were characterized using microspectrophotometry in retinas of three stomatopod species, Haptosquilla trispinosa, Gonodactylellus affinis, and Gonodactylopsis spongicola, comparing individuals of each species collected from shallow or deep water. Depending on the depth of collection, filters varied among individuals both in optical density and in spectral shape, and the variation that was observed was similar in all three species. The changes in filter density and spectrum increased absolute sensitivity in retinas of animals living at greater depths, and tuned their long-wavelength photoreceptors for improved function in the bluer light available in deep water. Plasticity in retinal spectral function may be common in mantis shrimp species that occupy a range of habitat depths.

  19. Modular organization of directionally tuned cells in the motor cortex: Is there a short-range order?

    Science.gov (United States)

    Amirikian, Bagrat; Georgopoulos, Apostolos P.

    2003-10-01

    We investigated the presence of short-range order (<600 μm) in the directional properties of neurons in the motor cortex of the monkey. For that purpose, we developed a quantitative method for the detection of functional cortical modules and used it to examine such potential modules formed by directionally tuned cells. In the functional domain, we labeled each cell by its preferred direction (PD) vector in 3D movement space; in the spatial domain, we used the position of the tip of the recording microelectrode as the cell's coordinate. The images produced by this method represented two orthogonal dimensions in the cortex; one was parallel ("horizontal") and the other perpendicular ("vertical") to the cortical layers. The distribution of directionally tuned cells in these dimensions was nonuniform and highly structured. Specifically, cells with similar PDs tended to segregate into vertically oriented minicolumns 50-100 μm wide and at least 500 μm high. Such minicolumns aggregated across the horizontal dimension in a secondary structure of higher order. In this structure, minicolumns with similar PDs were 200 μm apart and were interleaved with minicolumns representing nearly orthogonal PDs; in addition, nonoverlapping columns representing nearly opposite PDs were 350 μm apart.

  20. The effects of betatron phase advances on beam-beam and its compensation in RHIC

    Energy Technology Data Exchange (ETDEWEB)

    Luo, Y.; Fischer, W.; Gu, X.; Tepikian, S.; Trbojevic, D.

    2011-03-28

    In this article we perform simulation studies to investigate the effects of betatron phase advances between the beam-beam interaction points on half-integer resonance driving term, second order chromaticty and dynamic aperture in RHIC. The betatron phase advances are adjusted with artificial matrices inserted in the middle of arcs. The lattices for the 2011 RHIC polarized proton (p-p) run and 2010 RHIC Au-Au runs are used in this study. We also scan the betatron phase advances between IP8 and the electron lens for the proposed Blue ring lattice with head-on beam-beam compensation.

  1. Tuning light emission of PbS nanocrystals from infrared to visible range by cation exchange

    KAUST Repository

    Binetti, Enrico

    2015-10-27

    Colloidal semiconductor nanocrystals, with intense and sharp-line emission between red and near-infrared spectral regions, are of great interest for optoelectronic and bio-imaging applications. The growth of an inorganic passivation layer on nanocrystal surfaces is a common strategy to improve their chemical and optical stability and their photoluminescence quantum yield. In particular, cation exchange is a suitable approach for shell growth at the expense of the nanocrystal core size. Here, the cation exchange process is used to promote the formation of a CdS passivation layer on the surface of very small PbS nanocrystals (2.3 nm in diameter), blue shifting their optical spectra and yielding luminescent and stable nanostructures emitting in the range of 700–850 nm. Structural, morphological and compositional investigation confirms the nanocrystal size contraction after the cation-exchange process, while the PbS rock-salt crystalline phase is retained. Absorption and photoluminescence spectroscopy demonstrate the growth of a passivation layer with a decrease of the PbS core size, as inferred by the blue-shift of the excitonic peaks. The surface passivation strongly increases the photoluminescence intensity and the excited state lifetime. In addition, the nanocrystals reveal increased stability against oxidation over time. Thanks to their absorption and emission spectral range and the slow recombination dynamics, such highly luminescent nano-objects can find interesting applications in sensitized photovoltaic cells and light-emitting devices.

  2. Excitation Gaps of Finite-Sized Systems from Optimally Tuned Range-Separated Hybrid Functionals.

    Science.gov (United States)

    Kronik, Leeor; Stein, Tamar; Refaely-Abramson, Sivan; Baer, Roi

    2012-05-08

    Excitation gaps are of considerable significance in electronic structure theory. Two different gaps are of particular interest. The fundamental gap is defined by charged excitations, as the difference between the first ionization potential and the first electron affinity. The optical gap is defined by a neutral excitation, as the difference between the energies of the lowest dipole-allowed excited state and the ground state. Within many-body perturbation theory, the fundamental gap is the difference between the corresponding lowest quasi-hole and quasi-electron excitation energies, and the optical gap is addressed by including the interaction between a quasi-electron and a quasi-hole. A long-standing challenge has been the attainment of a similar description within density functional theory (DFT), with much debate on whether this is an achievable goal even in principle. Recently, we have constructed and applied a new approach to this problem. Anchored in the rigorous theoretical framework of the generalized Kohn-Sham equation, our method is based on a range-split hybrid functional that uses exact long-range exchange. Its main novel feature is that the range-splitting parameter is not a universal constant but rather is determined from first principles, per system, based on satisfaction of the ionization potential theorem. For finite-sized objects, this DFT approach mimics successfully, to the best of our knowledge for the first time, the quasi-particle picture of many-body theory. Specifically, it allows for the extraction of both the fundamental and the optical gap from one underlying functional, based on the HOMO-LUMO gap of a ground-state DFT calculation and the lowest excitation energy of a linear-response time-dependent DFT calculation, respectively. In particular, it produces the correct optical gap for the difficult case of charge-transfer and charge-transfer-like scenarios, where conventional functionals are known to fail. In this perspective, we overview

  3. 750 nm 1.5 W frequency-doubled semiconductor disk laser with a 44 nm tuning range.

    Science.gov (United States)

    Saarinen, Esa J; Lyytikäinen, Jari; Ranta, Sanna; Rantamäki, Antti; Sirbu, Alexei; Iakovlev, Vladimir; Kapon, Eli; Okhotnikov, Oleg G

    2015-10-01

    We demonstrate 1.5 W of output power at the wavelength of 750 nm by intracavity frequency doubling a wafer-fused semiconductor disk laser diode-pumped at 980 nm. An optical-to-optical efficiency of 8.3% was achieved using a bismuth borate crystal. The wavelength of the doubled emission could be tuned from 720 to 764 nm with an intracavity birefringent plate. The beam quality parameter M2 of the laser output was measured to be below 1.5 at all pump powers. The laser is a promising tool for biomedical applications that can take advantage of the large penetration depth of light in tissue in the 700-800 nm spectral range.

  4. A fully integrated VCO with a wide tuning range for DVB-H

    Science.gov (United States)

    Khemchandani, S. L.; Betancort, G.; del Pino Suarez, Javier; Alvarado, Unai; Goni-Iturri, Amaya; Hernandez, Antonio

    2007-05-01

    European standard DVB-T (Digital Video Broadcasting - Terrestrial) has already proven its exceptional features, including the possibility to receive broadcast services also with portable devices and even in receivers with a limited mobility such as cars. This paper presents a fully integrated LC voltage controlled oscillator (VCO) in a low cost 0.35 μm SiGe technology for DVB-H standard. To obtain VCO specifications system simulations have been done. The designed VCO is suitable to operate with ZERO and LOW IF receiver architectures. To integrate all the VCO components, it oscillates at double of the frequency band, from 940 to 1724 MHz. In order to sweep the whole frequency range, the tank is composed of an array of switched capacitors together with the varactors. The integrated inductors have been designed by electromagnetic simulations using Momentum(C). Techniques like using a capacitor divider, biasing the transistor for minimum noise and emitter degeneration have been utilized to improve phase noise requirements. The obtained phase noise is -108 dBc/Hz at 100 kHz offset and the power consumption, including the output buffers, is 28 mW.

  5. Weak-strong Beam-beam Simulations for HL-LHC

    Energy Technology Data Exchange (ETDEWEB)

    Banfi, Danilo [Ecole Polytechnique, Lausanne; Barranco, Javier [Ecole Polytechnique, Lausanne; Pieloni, Tatiana [CERN; Valishev, Alexander [Fermilab

    2014-07-01

    In this paper we present dynamic aperture studies for possible High Luminosity LHC optics in the presence of beam-beam interactions, crab crossing schemes and magnets multipolar errors. Possible operational scenarios of luminosity leveling by transverse offset and betatron function are also studied and the impact on the beams stability is discussed.

  6. Tuning of photoreceptor function in three mantis shrimp species that inhabit a range of depths. I. Visual pigments.

    Science.gov (United States)

    Cronin, Thomas W; Caldwell, Roy L; Erdmann, Mark V

    2002-04-01

    Visual pigments in many animal species, including stomatopod crustaceans, are adapted to the photic environments inhabited by that species. However, some species occupy a diversity of environments as adults (such as a range of depths in the ocean), and a single set of visual pigments would not be equally adaptive for all habitats in which individuals live. We characterized the visual pigment complements of three species of stomatopod crustaceans, Haptosquilla trispinosa, Gonodactylellus affinis, and Gonodactylopsis spongicola, which are unusual for this group in that each lives at depths from the subtidal to several tens of meters. Using microspectrophotometry, we determined the visual pigments in all classes of main rhabdoms in individuals of each species from shallow or deep habitats. Each species expressed the typical diversity of visual pigments commonly found in stomatopods, but there was little or no evidence of differential expression of visual pigments in animals of any species collected from different depths. Vision in these species, therefore, is not tuned to spectral characteristics of the photic environment by varying the assemblages of visual pigments appearing in their retinas.

  7. Tuning the dynamic range and sensitivity of optical oxygen-sensors by employing differently substituted polystyrene-derivatives

    Science.gov (United States)

    Koren, Klaus; Hutter, Lukas; Enko, Barbara; Pein, Andreas; Borisov, Sergey M.; Klimant, Ingo

    2013-01-01

    Ten different polystyrene-derivatives were tested with respect to their potential use as matrix materials for optical oxygen sensors in combination with the platinum(II) meso-tetra(4-fluorophenyl)tetrabenzoporphyrin as indicator dye. Either halogen atoms or bulky residues were introduced as substituents on the phenyl ring. A fine-tuning of the sensor sensitivity was achieved, without compromising solubility of the indicator in the matrix by providing a chemical environment very similar to polystyrene (PS), a standard matrix in optical oxygen sensors. To put the results into perspective, the studied materials were compared to PS regarding sensitivity of the sensor, molecular weight and glass-transition temperature. The materials promise to be viable alternatives to PS with respect to the requirements posed in various sensor application fields. Some of the polymers (e.g. poly(2,6-dichlorostyrene)) promise to be of use in applications requiring measurements from 0 to 100% oxygen due to linearity across this range. Poly(4-tert-butylstyrene) and poly(2,6-fluorostyrene), on the other hand, yield sensors with increased sensitivity. Sensor stability was evaluated as a function of the matrix, a topic which has not received a lot of interest so far. PMID:23576846

  8. Molecular mechanism of long-range synergetic color tuning between multiple amino acid residues in conger rhodopsin

    OpenAIRE

    Watanabe, Hiroshi C.; Mori, Yoshiharu; Tada, Takashi; Yokoyama, Shozo; Yamato, Takahisa

    2010-01-01

    The synergetic effects of multiple rhodopsin mutations on color tuning need to be completely elucidated. Systematic genetic studies and spectroscopy have demonstrated an interesting example of synergetic color tuning between two amino acid residues in conger rhodopsin's ancestral pigment (p501): —a double mutation at one nearby and one distant residue led to a significant λmax blue shift of 13 nm, whereas neither of the single mutations at these two sites led to meaningful shifts.

  9. Correction of beam-beam effects in luminosity measurement in the forward region at CLIC

    CERN Document Server

    Lukic, Strahinja

    2013-01-01

    Procedures for correcting the beam-beam effects in luminosity measurement at CLIC at 3 TeV CM energy are described and tested using Monte Carlo simulations: -> Correction of the angular counting loss due to the combined Beamstrahlung and initial-state radiation (ISR) effects, based on the reconstructed velocity of the collision frame of the Bhabha scattering. -> Deconvolution of the luminosity spectrum distortion due to the ISR emission. -> Correction of the counting bias due to the finite calorimeter energy resolution. All procedures were tested by simulation. Bhabha events were generated using BHLUMI, and used in Guinea-PIG to simulate the outgoing momenta of Bhabha particles in the bunch collisions at CLIC. Residual uncertainties after correction are listed in a table in the conclusions. The beam-beam related systematic counting uncertainty in the luminosity peak can be reduced to the order of permille.

  10. Correction of beam-beam effects in luminosity measurement in the forward region at CLIC

    CERN Document Server

    Lukic, Strahinja

    2013-01-01

    Procedures for correcting the beam-beam effects in luminosity measurement at CLIC at 3 TeV CM energy are described and tested using Monte Carlo simulations: - Correction of the angular counting loss due to the combined Beamstrahlung and initial-state radiation (ISR) effects, based on the reconstructed velocity of the collision frame of the Bhabha scattering. - Deconvolution of the luminosity spectrum distortion due to the ISR emission. - Correction of the counting bias due to the finite calorimeter energy resolution. All procedures were tested by simulation. Bhabha events were generated using BHLUMI, and used in Guinea-PIG to simulate the outgoing momenta of Bhabha particles in the bunch collisions at CLIC. Residual uncertainties after correction are listed in a table in the conclusions. The beam-beam related systematic counting uncertainty in the luminosity peak can be reduced to the order of permille.

  11. Recent and Past Experiences with Beam-Beam Effects at HERA

    Energy Technology Data Exchange (ETDEWEB)

    Minty, Michiko G

    1999-11-22

    Proton beam stability when in collision with high current electron bunches was of foremost concern during the design stages of the HERA collider[1]. In initial commissioning the beam-beam interaction proved to be a key factor in determining the lifetime of the proton beam. It was quickly ascertained[2] that the proton beam lifetime in collision could be substantially increased by both matching the electron and proton beam sizes ({sigma}) at the interaction points (IPs) and by carefully centering the beams. Presently, proton beam life times of hundreds of hours are routinely observed. In the near future, the accelerators will be upgraded[3] to include new low-{beta} insertions and to allow for yet higher beam currents. Key factors affecting the stability of colliding proton beams will be described as well as recent experiments performed to explore at high electron beam currents new regimes of the proton beam-beam limit at HERA.

  12. Novel tune diagnostics for the Tevatron

    Energy Technology Data Exchange (ETDEWEB)

    Tan, Cheng-Yang; /Fermilab

    2005-04-01

    In the Tevatron collider, protons and antiprotons share the same beam pipe. This poses a challenge in the measurement of tunes for both species simultaneously because of the possibility of signal contamination from the other species. The tune of each bunch is also very different because of beam-beam effects from parasitic crossing points. This means that the tune diagnostics must be able to differentiate between protons and anti-protons, it also has to measure tunes from each bunch. There are three different tune pickups used in the Tevatron: 1.7 GHz Schottky pickups, 21.4 MHz Schottky pickups and baseband pickups. These devices will be discussed in detail in this paper.

  13. Strong-Strong Simulation of Long-Range Beam-Beam Effects atRHIC

    Energy Technology Data Exchange (ETDEWEB)

    Qiang, Ji; Fischer, W.; Sen, T.

    2007-06-25

    As the development of extreme ultraviolet (EUV) lithography progresses, interest grows in the extension of traditional optical components to the EUV regime. The strong absorption of EUV by most materials and its extremely short wavelength, however, makes it very difficult to implement many components that are commonplace in the longer wavelength regimes. One such component is the diffractive optical element used, for example, in illumination systems to efficiently generate modified pupil fills. Here we demonstrate the fabrication and characterization of EUV binary phase-only computer-generated holograms allowing arbitrary far-field diffraction patterns to be generated.

  14. Status of RHIC head-on beam-beam compensation project

    Energy Technology Data Exchange (ETDEWEB)

    Fischer, W.; Anerella, M.; Beebe, E.; Bruno, D.; Gassner, D.M.; Gu, X.; Gupta, R.C.; Hock, J.; Jain, A.K.; Lambiase, R.; Liu, C.; Luo, Y.; Mapes, M.; Montag, C.; Oerter, B.; Okamura, M.; Pikin, A.I.; Raparia, D.; Tan, Y.; Than, R.; Thieberger, P.; Tuozzolo, J.; Zhang, W.

    2011-03-28

    Two electron lenses are under construction for RHIC to partially compensate the head-on beam-beam effect in order to increase both the peak and average luminosities. The final design of the overall system is reported as well as the status of the component design, acquisition, and manufacturing. An overview of the RHIC head-on beam-beam compensation project is given in [1], and more details in [2]. With 2 head-on beam-beam interactions in IP6 and IP8, a third interaction with a low-energy electron beam is added near IP10 to partially compensate the the head-on beam-beam effect. Two electron lenses are under construction, one for each ring. Both will be located in a region common to both beams, but each lens will act only on one beam. With head-on beam-beam compensation up to a factor of two improvement in luminosity is expected together with a polarized source upgrade. The current RHIC polarized proton performance is documented in Ref. [4]. An electron lens (Fig. 1) consists of an DC electron gun, warm solenoids to focus the electron beam during transport, a superconducting main solenoid in which the interaction with the proton beam occurs, steering magnets, a collector, and instrumentation. The main developments in the last year are given below. The experimental program for polarized program at 100 GeV was expected to be finished by the time the electron lenses are commissioned. However, decadal plans by the RHIC experiments STAR and PHENIX show a continuing interest at both 100 GeV and 250 GeV, and a larger proton beam size has been accommodated in the design (Tab. 1). Over the last year beam and lattice parameters were optimized, and RHIC proton lattices are under development for optimized electron lens performance. The effect of the electron lens magnetic structure on the proton beam was evaluated, and found to be correctable. Experiments were done in RHIC and the Tevatron.

  15. Numerical Simulation of Beam-Beam Effects in the Proposed Electron-Ion Colider at Jefferson Lab

    Energy Technology Data Exchange (ETDEWEB)

    Balsa Terzic, Yuhong Zhang

    2010-05-01

    One key limiting factor to a collider luminosity is beam-beam interactions which usually can cause serious emittance growth of colliding beams and fast reduction of luminosity. Such nonlinear collective beam effect can be a very serious design challenge when the machine parameters are pushed into a new regime. In this paper, we present simulation studies of the beam-beam effect for a medium energy ring-ring electron-ion collider based on CEBAF.

  16. Charge-transfer excitations in low-gap systems under the influence of solvation and conformational disorder: exploring range-separation tuning.

    Science.gov (United States)

    de Queiroz, Thiago B; Kümmel, Stephan

    2014-08-28

    Charge transfer excitations play a prominent role in the fields of molecular electronics and light harvesting. At the same time they have developed a reputation for being hard to predict with time-dependent density functional theory, which is the otherwise predominant method for calculating molecular structure and excitations. Recently, it has been demonstrated that range-separated hybrid functionals, in particular with an "optimally tuned" range separation parameter, describe charge-transfer excitations reliably for different molecules. Many of these studies focused on molecules in vacuum. Here we investigate the influence of solvation on the electronic excitations of thiophene oligomers, i.e., paradigm low gap systems. We take into account bulk solvation using a continuum solvation model and geometrical distortions from molecular dynamics. From our study, three main findings emerge. First, geometrical distortions increase absorption energies by about 0.5 eV for the longer thiophene oligomers. Second, combining optimal tuning of the range separation parameter with a continuum solvation method is not straightforward and has to be approached with great care. Third, optimally tuned range-separated hybrids without a short-range exchange component tend to inherit undesirable characteristics of semi-local functionals: with increasing system size the range separation parameter takes a smaller value, leading to a functional of effectively more semi-local nature and thus not accurately capturing, e.g., the saturation of the optical gap with increasing system size.

  17. Charge-transfer excitations in low-gap systems under the influence of solvation and conformational disorder: Exploring range-separation tuning

    Science.gov (United States)

    de Queiroz, Thiago B.; Kümmel, Stephan

    2014-08-01

    Charge transfer excitations play a prominent role in the fields of molecular electronics and light harvesting. At the same time they have developed a reputation for being hard to predict with time-dependent density functional theory, which is the otherwise predominant method for calculating molecular structure and excitations. Recently, it has been demonstrated that range-separated hybrid functionals, in particular with an "optimally tuned" range separation parameter, describe charge-transfer excitations reliably for different molecules. Many of these studies focused on molecules in vacuum. Here we investigate the influence of solvation on the electronic excitations of thiophene oligomers, i.e., paradigm low gap systems. We take into account bulk solvation using a continuum solvation model and geometrical distortions from molecular dynamics. From our study, three main findings emerge. First, geometrical distortions increase absorption energies by about 0.5 eV for the longer thiophene oligomers. Second, combining optimal tuning of the range separation parameter with a continuum solvation method is not straightforward and has to be approached with great care. Third, optimally tuned range-separated hybrids without a short-range exchange component tend to inherit undesirable characteristics of semi-local functionals: with increasing system size the range separation parameter takes a smaller value, leading to a functional of effectively more semi-local nature and thus not accurately capturing, e.g., the saturation of the optical gap with increasing system size.

  18. A physical model of a CMOS varactor with high capacitance tuning range and its application to simulate integrated VCOs

    Science.gov (United States)

    Maget, Judith; Kraus, Rainer; Tiebout, Marc

    2002-10-01

    A physical model of a novel MOS varactor design is presented. The voltage and frequency dependent results for the varactors small-signal capacitance and resistance agree well with measured values for different device geometries. The model is further tested through simulating a fully integrated voltage controlled oscillator (VCO) for UMTS applications. Measured frequency tuning and phase noise of the VCO are accurately reproduced.

  19. Tunable InGaN quantum dot microcavity light emitters with 129 nm tuning range from yellow-green to violet

    Science.gov (United States)

    Mei, Yang; Xu, Rong-Bin; Weng, Guo-En; Xu, Huan; Ying, Lei-Ying; Zheng, Zhi-Wei; Long, Hao; Zhang, Bao-Ping; Hofmann, Werner; Liu, Jian-Ping; Zhang, Jian; Li, Mo; Zhang, Jian

    2017-09-01

    An electrically pumped wavelength-tunable InGaN quantum dot (QD) based microcavity (MC) lighter emitter with a large tuning range of 129 nm was demonstrated. The multi-mode emission spectrum was tuned by injected current from 564 nm (yellow-green) to 435 nm (violet). The MC light emitter is featured with a double dielectric distributed Bragg reflector structure and a copper substrate fabricated using substrate transfer and laser lift off techniques. By utilizing an InGaN QD active layer with a tunable broad emission spectrum and a Fabry-Pérot cavity which allows multi-longitudinal mode resonating, the emission spectrum could be tuned among several particular cavity modes, which are decided by the gain enhancement factor. In addition, both the enhancement and suppression of MC emission modes caused by the gain enhancement factor were observed in a single MC device. As the first electrically driven III-V nitride semiconductor based tunable MC light emitter with a tuning range of 129 nm, the device is promising for applications such as in wide-gamut compact displays and projectors.

  20. Using distal site mutations and allosteric inhibition to tune, extend and narrow the useful dynamic range of aptamer-based sensors

    Science.gov (United States)

    Porchetta, Alessandro; Vallée-Bélisle, Alexis; Plaxco, Kevin W.; Ricci, Francesco

    2012-01-01

    Here we demonstrate multiple, complementary approaches by which to tune, extend or narrow the dynamic range of aptamer-based sensors. Specifically, we have employed both distal site mutations and allosteric control to tune the affinity and dynamic range of a fluorescent aptamer beacon. We show that allosteric control, achieved by using a set of easily designed oligonucleotide inhibitors that competes against the folding of the aptamer, allows to rationally and finely tune the affinity of our model aptamer across three orders of magnitude of target concentration with greater precision than that achieved using mutational approaches. Using these methods we generate sets of aptamers varying significantly in target affinity, which we then combined to recreate several of the mechanisms employed by nature to both narrow and broaden the dynamic range of biological receptors. Such ability to finely control the affinity and dynamic range of aptamers may find many applications in synthetic biology, drug delivery and targeted therapies, fields in which aptamers are of rapidly growing importance. PMID:23215257

  1. Tuning range and output power optimization of an external-cavity GaN diode laser at 455  nm.

    Science.gov (United States)

    Chi, Mingjun; Jensen, Ole Bjarlin; Petersen, Paul Michael

    2016-03-20

    In this paper we discuss how different feedback gratings affect the tuning range and the output power of external feedback diode laser systems. A tunable high-power narrow-spectrum external-cavity diode laser system around 455 nm is investigated. The laser system is based on a high-power GaN diode laser in a Littrow external-cavity. Both a holographic diffraction grating and a ruled diffraction grating are used as feedback elements in the external cavity. The output power, spectral bandwidth, and tunable range of the external cavity diode laser system are measured and compared with the two gratings at different injected currents. When the holographic grating is used, the laser system can be tuned over a range of 1.4 nm with an output power around 530 mW. When the ruled grating is used, the laser system can be tuned over a range of 6.0 nm with an output power around 80 mW. The results can be used as a guide for selecting gratings for external-cavity diode lasers for different requirements.

  2. Molecular mechanism of long-range synergetic color tuning between multiple amino acid residues in conger rhodopsin

    Science.gov (United States)

    Watanabe, Hiroshi C.; Mori, Yoshiharu; Tada, Takashi; Yokoyama, Shozo; Yamato, Takahisa

    2010-01-01

    The synergetic effects of multiple rhodopsin mutations on color tuning need to be completely elucidated. Systematic genetic studies and spectroscopy have demonstrated an interesting example of synergetic color tuning between two amino acid residues in conger rhodopsin’s ancestral pigment (p501): — a double mutation at one nearby and one distant residue led to a significant λmax blue shift of 13 nm, whereas neither of the single mutations at these two sites led to meaningful shifts. To analyze the molecular mechanisms of this synergetic color tuning, we performed homology modeling, molecular simulations, and electronic state calculations. For the double mutant, N195A/A292S, in silico mutation analysis demonstrated conspicuous structural changes in the retinal chromophore, whereas that of the single mutant, A292S, was almost unchanged. Using statistical ensembles of QM/MM optimized structures, the excitation energy of retinal chromophore was evaluated for the three visual pigments. As a result, the λmax shift of double mutant (DM) from p501 was −8 nm, while that of single mutant (SM) from p501 was +1 nm. Molecular dynamics simulation for DM demonstrated frequent isomerization between 6-s-cis and 6-s-trans conformers. Unexpectedly, however, the two conformers exhibited almost identical excitation energy, whereas principal component analysis (PCA) identified the retinal-counterion cooperative change of BLA (bond length alternation) and retinal-counterion interaction lead to the shift. PMID:21297892

  3. Contributions to the mini-workshop on beam-beam compensation in the Tevatron

    Energy Technology Data Exchange (ETDEWEB)

    Shiltsev, V.

    1998-02-01

    The purpose of the Workshop was to assay the current understanding of compensation of the beam-beam effects in the Tevatron with use of low-energy high-current electron beam, relevant accelerator technology, along with other novel techniques of the compensation and previous attempts. About 30 scientists representing seven institutions from four countries--FNAL, SLAC, BNL, Novosibirsk, CERN, and Dubna were in attendance. Twenty one talks were presented. The event gave firm ground for wider collaboration on experimental test of the compensation at the Tevatron collider. This report consists of vugraphs of talks given at the meeting.

  4. Recent Progress in a Beam-Beam Simulation Code for Circular Hadron Machines

    Energy Technology Data Exchange (ETDEWEB)

    Kabel, Andreas; /SLAC; Fischer, Wolfram; /Brookhaven; Sen, Tanaji; /Fermilab

    2007-09-10

    While conventional tracking codes can readily provide higher-order optical quantities and give an estimate of dynamic apertures, they are unable to provide directly measurable quantities such as lifetimes and loss rates. The particle tracking framework Plibb aims at modeling a storage ring with sufficient accuracy and a sufficiently high number of turns and in the presence of beam-beam interactions to allow for an estimate of these quantities. We provide a description of new features of the codes; we also describe a novel method of treating chromaticity in ring sections in a symplectic fashion.

  5. Charge-transfer excitations in low-gap systems under the influence of solvation and conformational disorder: Exploring range-separation tuning

    Energy Technology Data Exchange (ETDEWEB)

    Queiroz, Thiago B. de, E-mail: thiago.branquinho-de-queiroz@uni-bayreuth.de; Kümmel, Stephan [Theoretical Physics IV, University of Bayreuth, D-95440 Bayreuth (Germany)

    2014-08-28

    Charge transfer excitations play a prominent role in the fields of molecular electronics and light harvesting. At the same time they have developed a reputation for being hard to predict with time-dependent density functional theory, which is the otherwise predominant method for calculating molecular structure and excitations. Recently, it has been demonstrated that range-separated hybrid functionals, in particular with an “optimally tuned” range separation parameter, describe charge-transfer excitations reliably for different molecules. Many of these studies focused on molecules in vacuum. Here we investigate the influence of solvation on the electronic excitations of thiophene oligomers, i.e., paradigm low gap systems. We take into account bulk solvation using a continuum solvation model and geometrical distortions from molecular dynamics. From our study, three main findings emerge. First, geometrical distortions increase absorption energies by about 0.5 eV for the longer thiophene oligomers. Second, combining optimal tuning of the range separation parameter with a continuum solvation method is not straightforward and has to be approached with great care. Third, optimally tuned range-separated hybrids without a short-range exchange component tend to inherit undesirable characteristics of semi-local functionals: with increasing system size the range separation parameter takes a smaller value, leading to a functional of effectively more semi-local nature and thus not accurately capturing, e.g., the saturation of the optical gap with increasing system size.

  6. Simulation of beam-induced plasma for the mitigation of beam-beam effects

    Energy Technology Data Exchange (ETDEWEB)

    Ma, J.; Wang, G.; Samulyak, R.; Yu, K.; Litvinenko, V.

    2015-05-03

    One of the main challenges in the increase of luminosity of circular colliders is the control of the beam-beam effect. In the process of exploring beam-beam mitigation methods using plasma, we evaluated the possibility of plasma generation via ionization of neutral gas by proton beams, and performed highly resolved simulations of the beam-plasma interaction using SPACE, a 3D electromagnetic particle-in-cell code. The process of plasma generation is modelled using experimentally measured cross-section coefficients and a plasma recombination model that takes into account the presence of neutral gas and beam-induced electromagnetic fields. Numerically simulated plasma oscillations are consistent with theoretical analysis. In the beam-plasma interaction process, high-density neutral gas reduces the mean free path of plasma electrons and their acceleration. A numerical model for the drift speed as a limit of plasma electron velocity was developed. Simulations demonstrate a significant reduction of the beam electric field in the presence of plasma. Preliminary simulations using fully-ionized plasma have also been performed and compared with the case of beam-induced plasma.

  7. Development of a quartz tuning-fork-based force sensor for measurements in the tens of nanoNewton force range during nanomanipulation experiments

    Energy Technology Data Exchange (ETDEWEB)

    Oiko, V. T. A., E-mail: oiko@ifi.unicamp.br; Rodrigues, V.; Ugarte, D. [Instituto de Física “Gleb Wataghin,” Univ. Estadual de Campinas (UNICAMP), Campinas 13083-859 (Brazil); Martins, B. V. C. [Department of Physics, University of Alberta, Edmonton, Alberta T6G 2R3 (Canada); Silva, P. C. [Laboratório Nacional de Nanotecnologia, CNPEM, Campinas 13083-970 (Brazil)

    2014-03-15

    Understanding the mechanical properties of nanoscale systems requires new experimental and theoretical tools. In particular, force sensors compatible with nanomechanical testing experiments and with sensitivity in the nN range are required. Here, we report the development and testing of a tuning-fork-based force sensor for in situ nanomanipulation experiments inside a scanning electron microscope. The sensor uses a very simple design for the electronics and it allows the direct and quantitative force measurement in the 1–100 nN force range. The sensor response is initially calibrated against a nN range force standard, as, for example, a calibrated Atomic Force Microscopy cantilever; subsequently, applied force values can be directly derived using only the electric signals generated by the tuning fork. Using a homemade nanomanipulator, the quantitative force sensor has been used to analyze the mechanical deformation of multi-walled carbon nanotube bundles, where we analyzed forces in the 5–40 nN range, measured with an error bar of a few nN.

  8. Charge-Transfer Matrix Elements by FMO-LCMO Approach: Hole Transfer in DNA with Parameter Tuned Range-Separated DFT

    CERN Document Server

    Kitoh-Nishioka, Hirotaka

    2016-01-01

    A scheme for computing charge-transfer matrix elements with the linear combination of fragment molecular orbitals and the 'nonempirically tuned range-separated' density functional is presented. It takes account of the self-consistent orbital relaxation induced by environmental Coulomb field and the exchange interaction in fragment pairs at low computational scaling along the system size. The accuracy was confirmed numerically on benchmark systems of imidazole and furane homo-dimer cations. Applications to hole transfers in DNA nucleobase pairs and in a $\\pi$-stack adenine octomer highlight the effects of orbital relaxation.

  9. Degraded Frequency-Tuning Range and Oscillation Amplitude of LC-VCOs due to the Nonquasi-Static Effect in MOS Varactors

    Science.gov (United States)

    Miyake, Masataka; Hori, Daisuke; Sadachika, Norio; Feldmann, Uwe; Miura-Mattausch, Mitiko; Mattausch, Hans Jürgen; Ohguro, Tatsuya; Iizuka, Takahiro; Taguchi, Masahiko; Miyamoto, Shunsuke

    Frequency dependent properties of accumulation-mode MOS varactors, which are key elements in many RF circuits, are dominated by Non-Quasi-Static (NQS) effects in the carrier transport. The circuit performances containing MOS varactors can hardly be reproduced without considering the NQS effect in MOS-varactor models. For the LC-VCO circuit as an example it is verified that frequency-tuning range and oscillation amplitude can be overestimated by over 20% and more than a factor 2, respectively, without inclusion of the NQS effect.

  10. Sequence-specific long range networks in PSD-95/discs large/ZO-1 (PDZ) domains tune their binding selectivity.

    Science.gov (United States)

    Gianni, Stefano; Haq, S Raza; Montemiglio, Linda C; Jürgens, Maike C; Engström, Åke; Chi, Celestine N; Brunori, Maurizio; Jemth, Per

    2011-08-05

    Protein-protein interactions mediated by modular protein domains are critical for cell scaffolding, differentiation, signaling, and ultimately, evolution. Given the vast number of ligands competing for binding to a limited number of domain families, it is often puzzling how specificity can be achieved. Selectivity may be modulated by intradomain allostery, whereby a remote residue is energetically connected to the functional binding site via side chain or backbone interactions. Whereas several energetic pathways, which could mediate intradomain allostery, have been predicted in modular protein domains, there is a paucity of experimental data to validate their existence and roles. Here, we have identified such functional energetic networks in one of the most common protein-protein interaction modules, the PDZ domain. We used double mutant cycles involving site-directed mutagenesis of both the PDZ domain and the peptide ligand, in conjunction with kinetics to capture the fine energetic details of the networks involved in peptide recognition. We performed the analysis on two homologous PDZ-ligand complexes and found that the energetically coupled residues differ for these two complexes. This result demonstrates that amino acid sequence rather than topology dictates the allosteric pathways. Furthermore, our data support a mechanism whereby the whole domain and not only the binding pocket is optimized for a specific ligand. Such cross-talk between binding sites and remote residues may be used to fine tune target selectivity.

  11. Effect of a spectrometer magnet on the beam-beam interaction

    Energy Technology Data Exchange (ETDEWEB)

    Cornacchia, M; Parzen, G

    1981-01-01

    The presence of experimental apparatus in the interaction regions of an intersecting beam accelerator changes the configuration of the crossing beams. This changes the space-charge forces with respect to the standard, magnet-free crossing. The question is: what is the maximum allowable perturbation caused by the spectrometer magnet that can be tolerated from the point of view of the beam dynamics. This paper is limited to the perturbations that the curved trajectories cause the beam-beam space charge nonlinearities. The question has arisen of how one defines the strength of the perturbation. The only solution is to compute the strength of the most important nonlinear resources. In what follows, the computational method used in calculating these resonances is described, and compared with those induced by random orbit errors.

  12. Simulations on pair creation from beam-beam interaction in linear colliders

    Energy Technology Data Exchange (ETDEWEB)

    Chen, P.; Tauchi, T. (Stanford Linear Accelerator Center, Menlo Park, CA (USA)); Yokoya, K. (National Lab. for High Energy Physics, Tsukuba, Ibaraki (Japan))

    1991-05-01

    It has been recognized that e{sup +}e{sup {minus}} pair creation during the collision of intense beams in linear colliders will cause potential background problems for high energy experiments. Detailed knowledge of the angular-momentum spectrum of these low energy pairs is essential to the design of the interaction region. In this paper, we modify the computer code ABEL (Analysis of Beam-beam Effects in Linear colliders) to include the pair creation processes, using the equivalent photon approximation. Special care has been taken on the non-local nature of the virtual photon exchanges. The simulation results are then compared with known analytic formulas, and applied to the next generation colliders such as JLC. 10 refs., 2 figs.

  13. The E-lens test bench for RHIC beam-beam compensation

    Energy Technology Data Exchange (ETDEWEB)

    Gu X.; Altinbas, F.Z.; Aronson, J.; Beebe, E. et al

    2012-05-20

    To compensate for the beam-beam effects from the proton-proton interactions at IP6 and IP8 in the Relativistic Heavy Ion Collider (RHIC), we are fabricating two electron lenses that we plan to install at RHIC IR10. Before installing the e-lenses, we are setting-up the e-lens test bench to test the electron gun, collector, GS1 coil, modulator, partial control system, some instrumentation, and the application software. Some e-lens power supplies, the electronics for current measurement will also be qualified on test bench. The test bench also was designed for measuring the properties of the cathode and the profile of the beam. In this paper, we introduce the layout and elements of the e-lens test bench; and we discuss its present status towards the end of this paper.

  14. Lowest excited states and optical absorption spectra of donor–acceptor copolymers for organic photovoltaics: a new picture emerging from tuned long-range corrected density functionals

    KAUST Repository

    Pandey, Laxman

    2012-01-01

    Polymers with low optical gaps are of importance to the organic photovoltaics community due to their potential for harnessing a large portion of the solar energy spectrum. The combination along their backbones of electron-rich and electron-deficient fragments contributes to the presence of low-lying excited states that are expected to display significant charge-transfer character. While conventional hybrid functionals are known to provide unsatisfactory results for charge-transfer excitations at the time-dependent DFT level, long-range corrected (LRC) functionals have been reported to give improved descriptions in a number of systems. Here, we use such LRC functionals, considering both tuned and default range-separation parameters, to characterize the absorption spectra of low-optical-gap systems of interest. Our results indicate that tuned LRC functionals lead to simulated optical-absorption properties in good agreement with experimental data. Importantly, the lowest-lying excited states (excitons) are shown to present a much more localized nature than initially anticipated. © 2012 the Owner Societies.

  15. Lowest excited states and optical absorption spectra of donor-acceptor copolymers for organic photovoltaics: a new picture emerging from tuned long-range corrected density functionals.

    Science.gov (United States)

    Pandey, Laxman; Doiron, Curtis; Sears, John S; Brédas, Jean-Luc

    2012-11-01

    Polymers with low optical gaps are of importance to the organic photovoltaics community due to their potential for harnessing a large portion of the solar energy spectrum. The combination along their backbones of electron-rich and electron-deficient fragments contributes to the presence of low-lying excited states that are expected to display significant charge-transfer character. While conventional hybrid functionals are known to provide unsatisfactory results for charge-transfer excitations at the time-dependent DFT level, long-range corrected (LRC) functionals have been reported to give improved descriptions in a number of systems. Here, we use such LRC functionals, considering both tuned and default range-separation parameters, to characterize the absorption spectra of low-optical-gap systems of interest. Our results indicate that tuned LRC functionals lead to simulated optical-absorption properties in good agreement with experimental data. Importantly, the lowest-lying excited states (excitons) are shown to present a much more localized nature than initially anticipated.

  16. Organic electronic materials: Recent advances in the dft description of the ground and excited states using tuned range-separated hybrid functionals

    KAUST Repository

    Körzdörfer, Thomas

    2014-11-18

    Density functional theory (DFT) and its time-dependent extension (TD-DFT) are powerful tools enabling the theoretical prediction of the ground- and excited-state properties of organic electronic materials with reasonable accuracy at affordable computational costs. Due to their excellent accuracy-to-numerical-costs ratio, semilocal and global hybrid functionals such as B3LYP have become the workhorse for geometry optimizations and the prediction of vibrational spectra in modern theoretical organic chemistry. Despite the overwhelming success of these out-of-the-box functionals for such applications, the computational treatment of electronic and structural properties that are of particular interest in organic electronic materials sometimes reveals severe and qualitative failures of such functionals. Important examples include the overestimation of conjugation, torsional barriers, and electronic coupling as well as the underestimation of bond-length alternations or excited-state energies in low-band-gap polymers.In this Account, we highlight how these failures can be traced back to the delocalization error inherent to semilocal and global hybrid functionals, which leads to the spurious delocalization of electron densities and an overestimation of conjugation. The delocalization error for systems and functionals of interest can be quantified by allowing for fractional occupation of the highest occupied molecular orbital. It can be minimized by using long-range corrected hybrid functionals and a nonempirical tuning procedure for the range-separation parameter.We then review the benefits and drawbacks of using tuned long-range corrected hybrid functionals for the description of the ground and excited states of π-conjugated systems. In particular, we show that this approach provides for robust and efficient means of characterizing the electronic couplings in organic mixed-valence systems, for the calculation of accurate torsional barriers at the polymer limit, and for the

  17. Tuning anomalous Hall conductivity in L1[sub 0] FePt films by long range chemical ordering

    KAUST Repository

    Chen, M.

    2011-02-24

    For L10 FePt films, the anomalous Hall conductivity σ xy=-a σxx-b, where a=a0f(T), b=b 0f(T), and f (T) is the temperature dependence factor of the spontaneous magnetization. With increasing chemical long range ordering S, a0 changes its sign accompanied by a reduction of its magnitude and b0 increases monotonically. The spin-orbit coupling strength is suggested to increase with increasing S. As an approach, the long range chemical ordering can be used to control the anomalous Hall effect in ferromagnetic alloy films. © 2011 American Institute of Physics.

  18. Electrical and thermal tuning of quality factor and free spectral range of optical resonance of nematic liquid crystal microdroplets

    Science.gov (United States)

    Sofi, Junaid Ahmad; Mohiddon, M. A.; Dutta, N.; Dhara, Surajit

    2017-08-01

    We experimentally study the effect of temperature and electric field on the quality (Q ) factor and free spectral range (FSR) of whispering-gallery-mode optical resonance of dye-doped nematic liquid crystal microdroplets. Both the Q factor and the FSR are highly sensitive to the temperature and electric field and are tunable. The Q factor decreases, whereas the FSR increases substantially, with increasing temperature and electric field. The variation of the Q factor and FSR is understood based on the change in the effective refractive index and the dynamic size of the microdroplets.

  19. Ionization Energies, Electron Affinities, and Polarization Energies of Organic Molecular Crystals: Quantitative Estimations from a Polarizable Continuum Model (PCM)–Tuned Range-Separated Density Functional Approach

    KAUST Repository

    Sun, Haitao

    2016-05-16

    We propose a new methodology for the first-principles description of the electronic properties relevant for charge transport in organic molecular crystals. This methodology, which is based on the combination of a non-empirical, optimally tuned range-separated hybrid functional with the polarizable continuum model, is applied to a series of eight representative molecular semiconductor crystals. We show that it provides ionization energies, electron affinities, and transport gaps in very good agreement with experimental values as well as with the results of many-body perturbation theory within the GW approximation at a fraction of the computational costs. Hence, this approach represents an easily applicable and computationally efficient tool to estimate the gas-to-crystal-phase shifts of the frontier-orbital quasiparticle energies in organic electronic materials.

  20. Beam-Beam effects at the CMS BRIL van-der-Meer scans

    CERN Document Server

    CMS Collaboration

    2017-01-01

    The CMS Beam Radiation Instrumentation and Luminosity Project (BRIL) is devoted to the simulation and measurement of luminosity, beam conditions and radiation fields in the CMS Experiment at CERN. The project is engaged in operating and developing new detectors, compatible with the high luminosity experimental environments at the LHC. BRIL operates several detectors based on different physical principles and technologies. The detectors are calibrated using van-der-Meer scans to measure the luminosity that is a fundamental quantity of the LHC beam. In van-der-Meer scans the count rate in a detector is measured as a function of the distance between beams in the plane perpendicular to beam direction, to extract the underlying beam overlap area. The goal of the van-der-Meer scans is to obtain the calibration constant for each luminometer to be used at calibration then in physics data taking runs. The note presents the overview of beam-beam effects at the van-der-Meer scan and the corresponding corrections that sh...

  1. A Ku-band wide-tuning-range high-output-power VCO in InGaP/GaAs HBT technology

    Science.gov (United States)

    Jincan, Zhang; Yuming, Zhang; Hongliang, Lü; Yimen, Zhang; Bo, Liu; Leiming, Zhang; Fei, Xiang

    2015-06-01

    A fully integrated Ku-band voltage controlled oscillator (VCO) is presented in an InGaP/GaAs heterojunction bipolar transistor (HBT) technology. To achieve the wide tuning range (TR), the VCO employs a Colpitts configuration, and the VCO simultaneously achieves high output power. The implemented VCO demonstrates an oscillation frequency range from 12.82 to 14.97 GHz, a frequency TR of 15.47%, an output power from 0.31 to 6.46 dBm, and a phase noise of -94.9 dBc/Hz at 1 MHz offset from 13.9 GHz center frequency. The VCO consumes 52.75 mW from 5 V supply and occupies an area of 0.81 × 0.78 mm2. Finally, the figures-of-merit for VCOs is discussed. Project supported by the National Basic Research Program of China (No. 2010CBxxxx05), the Advance Research Project of China (No. 51308xxxx06), the Advance Research Foundation of China (No. 9140A08xxxx11DZ111), and Doctoral Scientific Research Foundation of Henan University of Science and Technology (No. 400613480011), and the Foundation of He'nan Educational Commettee (No. 15A510001).

  2. Analytical treatment of the nonlinear electron cloud effect and the combined effects with beam-beam and space charge nonlinear forces in storage rings

    Institute of Scientific and Technical Information of China (English)

    GAO Jie

    2009-01-01

    In this paper we treat first some nonlinear beam dynamics problems in storage rings, such as beam dynamic apertures due to magnetic multipoles, wiggles, beam-beam effects, nonlinear space charge effect, and then nonlinear electron cloud effect combined with beam-beam and space charge effects, analytically. This analytical treatment is applied to BEPC Ⅱ. The corresponding analytical expressions developed in this paper are useful both in understanding the physics behind these problems and also in making practical quick hand estimations.

  3. Fully integrated multi-optoelectronic synthesizer for THz pumping source in wireless communications with rich backup redundancy and wide tuning range

    Science.gov (United States)

    Xu, Junjie; Hou, Lianping; Deng, Qiufang; Han, Liangshun; Liang, Song; Marsh, John H.; Zhu, Hongliang

    2016-07-01

    We report a monolithic photonic integrated circuit (PIC) for THz communication applications. The PIC generates up to 4 optical frequency lines which can be mixed in a separate device to generate THz radiation, and each of the optical lines can be modulated individually to encode data. Physically, the PIC comprises an array of wavelength tunable distributed feedback lasers each with its own electro-absorption modulator. The lasers are designed with a long cavity to operate with a narrow linewidth, typically lasers is coupled via an multimode interference (MMI) coupler into a semiconductor optical amplifier (SOA). By appropriate selection and biasing of pairs of lasers, the optical beat signal can be tuned continuously over the range from 0.254 THz to 2.723 THz. The EAM of each channel enables signal leveling balanced between the lasers and realizing data encoding, currently at data rates up to 6.5 Gb/s. The PIC is fabricated using regrowth-free techniques, making it economic for volume applications, such for use in data centers. The PIC also has a degree of redundancy, making it suitable for applications, such as inter-satellite communications, where high reliability is mandatory.

  4. Reliable Prediction with Tuned Range-Separated Functionals of the Singlet-Triplet Gap in Organic Emitters for Thermally Activated Delayed Fluorescence (TADF)

    KAUST Repository

    Sun, Haitao

    2015-07-09

    The thermally activated delayed fluorescence (TADF) mechanism has recently attracted much interest in the field of organic light-emitting diodes (OLEDs). TADF relies on the presence of a very small energy gap between the lowest singlet and triplet excited states. Here, we demonstrate that time-dependent density functional theory (TD-DFT) in the Tamm-Dancoff Approximation can be very successful in the calculations of the lowest singlet and triplet excitation energies and the corresponding singlet-triplet gap when using nonempirically tuned range-separated functionals. Such functionals provide very good estimates in a series of 17 molecules used in TADF-based OLED devices, with mean absolute deviations of 0.15 eV for the vertical singlet excitation energies and 0.09 eV [0.07 eV] for the adiabatic [vertical] singlet-triplet energy gaps as well as low relative errors and high correlation coefficients compared to the corresponding experimental values. They significantly outperform conventional functionals, a feature which is rationalized on the basis of the amount of exact-exchange included and the delocalization error. The present work provides a reliable theoretical tool for the prediction and development of novel TADF-based materials with low singlet-triplet energetic splittings.

  5. A Multi-Bunch, Three-Dimensional, Strong-Strong Beam-Beam Simulation Code for Parallel Computers

    Energy Technology Data Exchange (ETDEWEB)

    Cai, Y.; Kabel, A.C.; /SLAC

    2005-05-11

    For simulating the strong-strong beam-beam effect, using Particle-In-Cell codes has become one of the methods of choice. While the two-dimensional problem is readily treatable using PC-class machines, the three-dimensional problem, i.e., a problem encompassing hourglass and phase-averaging effects, requires the use of parallel processors. In this paper, we introduce a strong-strong code NIMZOVICH, which was specifically designed for parallel processors and which is optimally used for many bunches and parasitic crossings. We describe the parallelization scheme and give some benchmarking results.

  6. Compensation of beam-beam and space-charge effects: experience to-date and near-future opportunities

    CERN Document Server

    Shiltsev, V

    2014-01-01

    Beam-beam interactions and space-charge effects belong to the category of the most long-standing issues in beam physics, and even today, after several decades of very active exploration and development of counter-measures, they still pose the most profound limitations on performance of accelerator facilities. In this brief review we consider past experience in active compensation of these effects and possible new schemes for further exploration in near-future, in particular, within the framework of the electron-ion collider R&D.

  7. A 2GHz, 17% tuning range quadrature CMOS VCO with high figure–of–merit and 0.6° phase error

    DEFF Research Database (Denmark)

    Andreani, Pietro

    2002-01-01

    This paper presents a quadrature VCO implemented in a standard 0.35µm CMOS process. The VCO draws 16mA from a 1.3V power supply, can be tuned between 1.91 GHz and 2.27GHz, and displays a phase noise of -140dBc/Hz or less at 3MHz offset frequency from the carrier, for a minimum phase-noise figure......-of-merit of 184 dB. The maximum departure from quadrature between the VCO phases is 0.6°....

  8. Experimental demonstration of change of dynamical properties of a passively mode-locked semiconductor laser subject to dual optical feedback by dual full delay-range tuning.

    Science.gov (United States)

    Nikiforov, O; Jaurigue, L; Drzewietzki, L; Lüdge, K; Breuer, S

    2016-06-27

    In this contribution we experimentally demonstrate the change and improvement of dynamical properties of a passively mode-locked semiconductor laser subject to optical feedback from two external cavities by coupling the feedback pulses back into the gain segment. Hereby, we tune the full delay-phase of the pulse-to-pulse period of both external cavities separately and demonstrate the change of the repetition rate, timing jitter, multi-pulse formation and side-band suppression for the first time for such a dual feedback configuration. In addition, we thereby confirm modeling predictions by achieving both a good qualitative and quantitative agreement of experimental and simulated results. Our findings suggest a path towards the realization of side-band free all-optical photonic oscillators based on mode-locked lasers.

  9. Radiation and Background Levels in a CLIC Detector due to Beam-Beam Effects Optimisation of Detector Geometries and Technologies

    CERN Document Server

    Sailer, André; Lohse, Thomas

    2013-01-10

    The high charge density---due to small beam sizes---and the high energy of the proposed CLIC concept for a linear electron--positron collider with a centre-of-mass energy of up to 3~TeV lead to the production of a large number of particles through beam-beam interactions at the interaction point during every bunch crossing (BX). A large fraction of these particles safely leaves the detector. A still significant amount of energy will be deposited in the forward region nonetheless, which will produce secondary particles able to cause background in the detector. Furthermore, some particles will be created with large polar angles and directly cause background in the tracking detectors and calorimeters. The main sources of background in the detector, either directly or indirectly, are the incoherent $mathrm{e}^{+}mathrm{e}^{-}$ pairs and the particles from $gammagamma ightarrow$ hadron events. The background and radiation levels in the detector have to be estimated, to study if a detector is feasible, that can han...

  10. Design of Low Phase Noise Voltage Controlled Oscillator with Low Tuning-gain Change and Wide Linear Range%低增益变化宽线性范围低噪声压控振荡器设计

    Institute of Scientific and Technical Information of China (English)

    郑金汪; 陈华; 倪侃; 郭桂良; 张润曦; 刘生有; 来强涛; 阎跃鹏

    2014-01-01

    Based on 0 .18 μm CMOS process ,a low power low phase noise broadband VCO with low tuning-gain change constant tuning curve interval and constant output swing was presented .Switched capacitor array ,varactor array with bias voltage and the tail current array was included in this VCO .The tuning range of VCO is 1 .153~1.911 GHz(49 .5% ) .The coverage of adjacent tuning curve is more than 50% .The tuning-gain of VCO is 45 .5~52.7 M Hz/V (13 .7% ) .The space of adjacent tuning curve is 43 .2~45 .9 M Hz(5 .9% ) .The output swing of VCO is 694~715 mV(3% ) .The linear range of tuning curve is 0 .2~1 .6 V(1 .4 V) .At a 1 .8 V supply and the center frequency 1 .53 GHz ,the VCO measures a phase noise of-130 .5 dBc/Hz@ 1 MHz offset while dissipating 3 .2 mA current .T he FOM of the VCO is -186 .5 dBc/Hz .%应用 TSMC 0.18μm CMOS工艺设计了一款低调谐增益变化,恒定调谐曲线间隔,恒定输出摆幅的低功耗低噪声宽带压控振荡器(Voltage Controlled Oscillator ,VCO).本振荡器的振荡频率覆盖1.153~1.911 GHz (49.5%)范围,相邻调谐曲线的覆盖范围大于50%,调谐增益变化范围为45.5~52.7 M Hz/V (13.7%),相邻调谐曲线间距变化范围为43.2~45.9 M Hz(5.9%),VCO输出波形的峰峰值为694~715 mV (3%),调谐曲线的线性范围为0.2~1.6V(1.4V).在1.8V的电源电压下,VCO在中心频率1.53GHz处耗电电流为3.2mA,相位噪声在1 M Hz频偏处为-130.5 dBc/Hz ,FOM值为-186.5 dBc/Hz .

  11. Observations and measurements of dynamic effects due to beam-beam interactions in the LHC and extrapolation to the FCC-hh

    CERN Document Server

    Goncalves Jorge, Patrik

    The Future Circular hadron-hadron Collider (FCC-hh) is a design study for a 100 TeV centre-of-mass energy. The dynamics of the beams in such a collider poses many challenges, in particular the amount of energy stored in each beam (8.4 GJ) makes them very destructive and therefore requires a tight control of the machine and beam parameters during the full cycle in order to avoid damages and reach the collider designed performances. The FCC-hh features an increase of the beam brightness during the cycle due to the presence of synchrotron radiation damping at high energy. As a result, the electromagnetic forces that the two beams exert on each other, the so-called beam-beam forces, are enhanced and might become an issue for the safe operation of the machine. In this new regime, the impact of the beam-beam interaction on the optics becomes non-negligible. In this master thesis, for the first time, the impact of the beam-beam interaction on the optics ($\\beta$-beating) is measured in a hadron collider (LHC). The e...

  12. SC tuning fork

    CERN Multimedia

    The tuning fork used to modulate the radiofrequency system of the synchro cyclotron (SC) from 1957 to 1973. This piece is an unused spare part. The SC was the 1st accelerator built at CERN. It operated from August 1957 until it was closed down at the end of 1990. In the SC the magnetic field did not change with time, and the particles were accelerated in successive pulses by a radiofrequency voltage of some 20kV which varied in frequency as they spiraled outwards towards the extraction radius. The frequency varied from 30MHz to about 17Mz in each pulse. The tuning fork vibrated at 55MHz in vacuum in an enclosure which formed a variable capacitor in the tuning circuit of the RF system, allowing the RF to vary over the appropriate range to accelerate protons from the centre of the macine up to 600Mev at extraction radius. In operation the tips of the tuning fork blade had an amplitude of movement of over 1 cm. The SC accelerator underwent extensive improvements from 1973 to 1975, including the installation of a...

  13. An efficient plane-grating monochromator based on conical diffraction for continuous tuning in the entire soft X-ray range including tender X-rays (2-8 keV).

    Science.gov (United States)

    Jark, Werner

    2016-01-01

    Recently it was verified that the diffraction efficiency of reflection gratings with rectangular profile, when illuminated at grazing angles of incidence with the beam trajectory along the grooves and not perpendicular to them, remains very high for tender X-rays of several keV photon energy. This very efficient operation of a reflection grating in the extreme off-plane orientation, i.e. in conical diffraction, offers the possibility of designing a conical diffraction monochromator scheme that provides efficient continuous photon energy tuning over rather large tuning ranges. For example, the tuning could cover photon energies from below 1000 eV up to 8 keV. The expected transmission of the entire instrument is high as all components are always operated below the critical angle for total reflection. In the simplest version of the instrument a plane grating is preceded by a plane mirror rotating simultaneously with it. The photon energy selection will then be made using the combination of a focusing mirror and exit slit. As is common for grating monochromators for soft X-ray radiation, the minimum spectral bandwidth is source-size-limited, while the bandwidth can be adjusted freely to any larger value. As far as tender X-rays (2-8 keV) are concerned, the minimum bandwidth is at least one and up to two orders of magnitude larger than the bandwidth provided by Si(111) double-crystal monochromators in a collimated beam. Therefore the instrument will provide more flux, which can even be increased at the expense of a bandwidth increase. On the other hand, for softer X-rays with photon energies below 1 keV, competitive relative spectral resolving powers of the order of 10000 are possible.

  14. A CMOS LC VCO with 3.2~6.1GHz Tuning Range%频率覆盖3.2~6.1 GHz的CMOS LC VCO

    Institute of Scientific and Technical Information of China (English)

    宁彦卿; 池保勇; 王志华; 陈弘毅

    2007-01-01

    The design and implementation of a CMOS LC VCO with 3.2~6.1 GHz tuning range are presented. This is achieved by enhancing the tuning capability of the binary-weighted band-switching MIM capacitor. The circuit has been implemented in a 0.18μm RF/Mixed-Signal CMOS process. The measured phase noise is - 101.67dBc/Hz at 1MHz offset from a 5.5GHz carrier,and the VCO core draws 9. 69mA current from a 1.8V supply.%通过提高MIM电容的调整范围,实现了一个覆盖3.2~6.1 GHz的CMOS LC VCO.该VCO使用0.18μm射频CMOS工艺制作,芯片面积约为1260μm×670μm.当输出5.5GHz时,VCO内核消耗功率为17.5mW;在100kHz频偏处的相位噪声是~101.67dBc/Hz.

  15. Simulations of the Static Tuning for the TESLA Linear Collider

    CERN Document Server

    Schulte, Daniel

    2003-01-01

    At the heart of the TESLA linear collider are the two 10 km long superconducting linacs. A linac is constructed from 858 cryomodules each containing 12 nine-cell 1.3 GHz superconducting cavities. 355 quadrupoles provide the necessary beam focusing. The advantages of low-frequency superconducting RF in terms of wakefield behaviour are well known, and the TESLA alignment tolerances are relatively loose. However, the effects of cavity tilts and their impact of the linac beam-based alignment algorithms have until recently not been fully investigated. In addition, the strong sensitivity to correlated emittance growth due to the high beam-beam disruption parameter makes it desirable to control the linac emittance down to a few percent. In this report we discuss various static tuning algorithms and present new simulation results. Discussions of the relative merits and applicability of the methods is also discussed.

  16. Integrated Analogic Filter Tuning System Design

    Directory of Open Access Journals (Sweden)

    Karolis Kiela

    2016-06-01

    Full Text Available Parameters of integrated analog filters can vary due to temperatu-re change, IC process variation and therefore they should have dedicated tuning circuits that compensate these imperfections. A method is proposed that speeds up switched resistor bank design while taking into account the required tuning range and step size. A novel counter structure is used in the tuning circuit that is ba-sed on successive approximation approach. The proposed swit-ched resistor design method and tuning circuit are designed in 0.18 μm CMOS technology and verified. Results are compared to existing tuning circuit designs.

  17. Non-linear beam-beam forces in storage rings. Particular analysis for S. S. C. and L. H. C. parameters

    Energy Technology Data Exchange (ETDEWEB)

    Pusterla, M.; Servizi, G.; Turchetti, G.

    1985-10-01

    Theoretical models, suitable for description of the long behaviour of bunched and unbunched beams of particles in accelerators and storage rings, are becoming more and more appreciated by physicists that want a high luminosity joined with the stability of the beams. Such a point is going to be particulary important for the next generation machines as L.E.P., S.S.C. and L.H.C. In this note we are giving a simplified analysis of the beam-beam non-linear effects for proton colliders on the basis of the latest designs (we think of S.S.C. and L.H.C.). Before doing that, however, we like to consider the general features of the dynamical approaches that describe the beam-beam forces both for the proton proton rings (fixed angle collision) and for proton-antiproton or electronpositron rings (head-on collisions): they follow directly from the recent developments of non-linear classical mechanics, namely the K.A.M. theorem and the transition to a chaotic motion in deterministic mechanical systems.

  18. 一种低抖动、宽调节范围的带宽自适应CMOS锁相环%An Adaptive-Bandwidth CMOS PLL with Low Jitter and a Wide Tuning Range

    Institute of Scientific and Technical Information of China (English)

    宋颖; 王源; 贾嵩; 李宏义; 赵宝瑛; 吉利久

    2008-01-01

    提出了一种低抖动、宽调节范围的带宽自适应CMOS锁相环.由于环路带宽可根据输入频率进行自动调节,电路性能可在整个工作频率范围内得到优化.为了进一步提高电路的抖动特性,在电荷泵电路中采用匹配技术,并在压控振荡器中应用电压-电压转换电路以减小压控振荡器的增益.芯片采用SMIC 0.35μm CMOS工艺加工.测试结果表明该锁相环电路可在200MHz~1.1GHz的输出频率范围内保持良好的抖动性能.%This paper presents a novel adaptive-bandwidth charge pump PLL with low jitter and a wide tuning range. Withan adaptive bandwidth,the proposed PLL can scale its loop dynamics proportional to the output frequency and maintainoptimal performance over its entire output range. In order to improve the jitter performance of the PLL,a matching tech-nique is employed in the charge pump,and a voltage-to-voltage converter is used to achieve a low gain VCO. The experi-mental chip was fabricated in a 0. 35μm CMOS process. The measured results show that the PLL has perfect jitter per-formance within its operating range from 200MHz to 1.1GHz.

  19. An optical device for laser tuning

    Energy Technology Data Exchange (ETDEWEB)

    Sinyitiro, A.

    1984-01-31

    This invention is intended to improve on the design of an optical device which is used to execute high precision tuning of the optical elements in laser systems. A laser tuning scheme is given and the tuning method is described in detail. The tuning system includes a laser emission source in the visible spectral range and a semitransparent plate at an angle of 45 degrees with respect to the optical axis of the laser. When a test beam passes through the plate, a portion of the emission is reflected to a screen containing a reference mark. The remaining portion of the emission passes through the plate and is reflected from the rear dark mirror in the laser under tuning. The second beam is reflected from the plate to the other screen. The reference marks on the screens represent the optimum position of the optical elements of the laser system, which provides good laser tuning accuracy.

  20. Self-tuning tuned mass damper (TMD)

    Science.gov (United States)

    Griffin, Steven

    2017-04-01

    Tuned mass dampers (TMD) are heavily damped resonant devices which add damping to lightly damped, vibrational modes of a structure by dynamically coupling into the lightly damped modes. In practice, a TMD is a damped spring/mass resonator that is tuned so that its frequency is close to a lightly damped mode on the host structure. The TMD is attached to the host structure at a location of large amplitude motion for the mode to be dampened, and its motion is coupled into the host structure's motion. If the TMD is tuned correctly, two damped vibrational modes result, which take the place of the original lightly damped mode of the host structure and heavily damped mode of the TMD. Since aerospace structures tend to respond unfavorably at lightly damped modes in the presence of a dynamic disturbance environment, introduction of one or several TMDs can greatly reduce the dynamic response of a structure by damping problematic modes. A self-tuning TMD is described that can perform all the steps necessary to automatically tune itself and minimize the response of a structure with lightly damped modes and a dynamic excitation. The self-tuning TMD concept introduced here uses a voice coil / magnet combination as -an actuator which enables an innovative stiffness adjustment mechanism -a loss mechanism for the tuned mass damper -a means of excitation for identifying lightly damped modes of the host structure Along with an accelerometer and a tethered power supply/computer, the self-tuning TMD can automatically identify and damp lightly damped modes.

  1. TUNE FEEDBACK AT RHIC

    Energy Technology Data Exchange (ETDEWEB)

    CAMERON,P.; CERNIGLIA,P.; CONNOLLY,R.; CUPOLO,J.; DAWSON,W.C.; DEGEN,C.; DELLAPENNA,A.; DELONG,J.; DREES,A.; HUHN,A.; KESSELMAN,M.; MARUSIC,A.; OERTER,B.; MEAD,J.; SCHULTHEISS,C.; SIKORA,R.; VAN ZEIJTS,J.

    2001-06-18

    Preliminary phase-locked loop betatron tune measurement results were obtained during RHIC 2000 with a resonant Beam Position Monitor. These results suggested the possibility of incorporating PLL tune measurement into a tune feedback system for RHIC 2001. Tune feedback is useful in a superconducting accelerator, where the machine cycle time is long and inefficient acceleration due to resonance crossing is not comfortably tolerated. This is particularly true with the higher beam intensities planned for RHIC 2001. We present descriptions of a PLL tune measurement system implemented in the DSP/FPGA environment of a RHIC BPM electronics module and the feedback system into which the measurement is incorporated to regulate tune. In addition, we present results from the commissioning of this system during RHIC 2001.

  2. Tuning Higher Education

    Science.gov (United States)

    Carroll, Bradley

    2011-03-01

    In April 2009, the Lumina Foundation launched its Tuning USA project. Faculty teams in selected disciplines from Indiana, Minnesota, and Utah started pilot Tuning programs at their home institutions. Using Europe's Bologna Process as a guide, Utah physicists worked to reach a consensus about the knowledge and skills that should characterize the 2-year, batchelor's, and master's degree levels. I will share my experience as a member of Utah's physics Tuning team, and describe our progress, frustrations, and evolving understanding of the Tuning project's history, methods, and goals.

  3. Development of the System Test for the LHC Tune Measurement and Abort Gap Monitoring

    CERN Document Server

    Beccati, B

    2008-01-01

    The Large Hadron Collider (LHC) is the largest accelerator in the world and it will collide opposing beams of 7 TV protons together. It is built inside a 27km tunnel on the border between France and Switzerland. Within the framework of the project IUSS- Ferrara, I collaborated with the members of the AB-BI section at CERN: Accelerator Beam - Beam Instrumentation. My degree thesis is the result of this cooperation. My project is made of two sections, one for each themes analyzed during this year at CERN: the first one concerns the Tune, the second one is about the Abort gap. LHC is a synchrotron, an accelerator using dipole magnets to bending and quadrupole magnets to transverse focusing. Passing through this pattern of magnets, particles make oscillations. We refer to these ones as Betatron oscillations. The number of such oscillations/turn is called Tune. The ability tomeasure the tune is important for many kinds of diagnostic. In the base band tune (BBQ) measurement system developed at CERN the signal is di...

  4. Java performance tuning

    CERN Document Server

    Shirazi, Jack

    2003-01-01

    Performance has been an important issue for Java developers ever since the first version hit the streets. Over the years, Java performance has improved dramatically, but tuning is essential to get the best results, especially for J2EE applications. You can never have code that runs too fast. Java Peformance Tuning, 2nd edition provides a comprehensive and indispensable guide to eliminating all types of performance problems. Using many real-life examples to work through the tuning process in detail, JPT shows how tricks such as minimizing object creation and replacing strings with arrays can

  5. TUNE: Compiler-Directed Automatic Performance Tuning

    Energy Technology Data Exchange (ETDEWEB)

    Hall, Mary [University of Utah

    2014-09-18

    This project has developed compiler-directed performance tuning technology targeting the Cray XT4 Jaguar system at Oak Ridge, which has multi-core Opteron nodes with SSE-3 SIMD extensions, and the Cray XE6 Hopper system at NERSC. To achieve this goal, we combined compiler technology for model-guided empirical optimization for memory hierarchies with SIMD code generation, which have been developed by the PIs over the past several years. We examined DOE Office of Science applications to identify performance bottlenecks and apply our system to computational kernels that operate on dense arrays. Our goal for this performance-tuning technology has been to yield hand-tuned levels of performance on DOE Office of Science computational kernels, while allowing application programmers to specify their computations at a high level without requiring manual optimization. Overall, we aim to make our technology for SIMD code generation and memory hierarchy optimization a crucial component of high-productivity Petaflops computing through a close collaboration with the scientists in national laboratories.

  6. Robust Self Tuning Controllers

    DEFF Research Database (Denmark)

    Poulsen, Niels Kjølstad

    1985-01-01

    The present thesis concerns robustness properties of adaptive controllers. It is addressed to methods for robustifying self tuning controllers with respect to abrupt changes in the plant parameters. In the thesis an algorithm for estimating abruptly changing parameters is presented. The estimator...... has several operation modes and a detector for controlling the mode. A special self tuning controller has been developed to regulate plant with changing time delay....

  7. Non-linear dendrites can tune neurons

    Directory of Open Access Journals (Sweden)

    Romain Daniel Cazé

    2014-03-01

    Full Text Available A signature of visual, auditory, and motor cortices is the presence of neurons tuned to distinct features of the environment. While neuronal tuning can be observed in most brain areas, its origin remains enigmatic, and new calcium imaging data complicate this problem. Dendritic calcium signals, in a L2/3 neuron from the mouse visual cortex, display a wide range of tunings that could be different from the neuronal tuning (Jia et al 2010. To elucidate this observation we use multi-compartmental models of increasing complexity, from a binary to a realistic biophysical model of L2/3 neuron. These models possess non-linear dendritic subunits inside which the result of multiple excitatory inputs is smaller than their arithmetic sum. While dendritic non-linear subunits are ad-hoc in the binary model, non-linearities in the realistic model come from the passive saturation of synaptic currents. Because of these non-linearities our neuron models are scatter sensitive: the somatic membrane voltage is higher when presynaptic inputs target different dendrites than when they target a single dendrite. This spatial bias in synaptic integration is, in our models, the origin of neuronal tuning. Indeed, assemblies of presynaptic inputs encode the stimulus property through an increase in correlation or activity, and only the assembly that encodes the preferred stimulus targets different dendrites. Assemblies coding for the non-preferred stimuli target single dendrites, explaining the wide range of observed tunings and the possible difference between dendritic and somatic tuning. We thus propose, in accordance with the latest experimental observations, that non-linear integration in dendrites can generate neuronal tuning independently of the coding regime.

  8. Complier-Directed Automatic Performance Tuning (TUNE) Final Report

    Energy Technology Data Exchange (ETDEWEB)

    Chame, Jacqueline [USC-ISI

    2013-06-07

    TUNE was created to develop compiler-directed performance tuning technology targeting the Cray XT4 system at Oak Ridge. TUNE combines compiler technology for model-guided empirical optimization for memory hierarchies with SIMD code generation. The goal of this performance-tuning technology is to yield hand-tuned levels of performance on DOE Office of Science computational kernels, while allowing application programmers to specify their computations at a high level without requiring manual optimization. Overall, TUNE aims to make compiler technology for SIMD code generation and memory hierarchy optimization a crucial component of high-productivity Petaflops computing through a close collaboration with the scientists in national laboratories.

  9. Complier-Directed Automatic Performance Tuning (TUNE) Final Report

    Energy Technology Data Exchange (ETDEWEB)

    Chame, Jacqueline [USC-ISI

    2013-06-07

    TUNE was created to develop compiler-directed performance tuning technology targeting the Cray XT4 system at Oak Ridge. TUNE combines compiler technology for model-guided empirical optimization for memory hierarchies with SIMD code generation. The goal of this performance-tuning technology is to yield hand-tuned levels of performance on DOE Office of Science computational kernels, while allowing application programmers to specify their computations at a high level without requiring manual optimization. Overall, TUNE aims to make compiler technology for SIMD code generation and memory hierarchy optimization a crucial component of high-productivity Petaflops computing through a close collaboration with the scientists in national laboratories.

  10. Planck-LFI radiometers tuning

    Energy Technology Data Exchange (ETDEWEB)

    Cuttaia, F; Stringhetti, L; Terenzi, L; Villa, F; Butler, R C; Franceschi, E [Istituto di Astrofisica Spaziale e Fisica Cosmica, INAF, via P. Gobetti 101, 40129 Bologna (Italy); Mennella, A; Tomasi, M; Bersanelli, M; Cappellini, B; Franceschet, C; Hoyland, R [Universita degli Studi di Milano, via Celoria 16, 20133 Milano (Italy); Maris, M; Frailis, M [INAF / OATS, via Tiepolo 11, 34143 Trieste (Italy); Cuevas, L P [Research and Scientific Support Department of ESA, ESTEC, Noordwijk (Netherlands); D' Arcangelo, O [IFP-CNR, via Cozzi 53, 20013 Milano (Italy); Davis, R; Lowe, S [Jodrell Bank Centre for Astrophysics, Alan Turing Building, The University of Manchester, Manchester, M13 9PL (United Kingdom); Gregorio, A [University of Trieste, Department of Physics, via Valerio 2, 34127 Trieste (Italy); Leonardi, R, E-mail: cuttaia@iasfbo.inaf.i [Department of Physics, University of California, Santa Barbara, CA 93106-9530 (United States)

    2009-12-15

    This paper describes the Planck Low Frequency Instrument tuning activities performed through the ground test campaigns, from Unit to Satellite Levels. Tuning is key to achieve the best possible instrument performance and tuning parameters strongly depend on thermal and electrical conditions. For this reason tuning has been repeated several times during ground tests and it has been repeated in flight before starting nominal operations. The paper discusses the tuning philosophy, the activities and the obtained results, highlighting developments and changes occurred during test campaigns. The paper concludes with an overview of tuning performed during the satellite cryogenic test campaign (Summer 2008) and of the plans for the just started in-flight calibration.

  11. Adaptive Tuning Algorithm for Performance tuning of Database Management System

    CERN Document Server

    Rodd, S F

    2010-01-01

    Performance tuning of Database Management Systems(DBMS) is both complex and challenging as it involves identifying and altering several key performance tuning parameters. The quality of tuning and the extent of performance enhancement achieved greatly depends on the skill and experience of the Database Administrator (DBA). As neural networks have the ability to adapt to dynamically changing inputs and also their ability to learn makes them ideal candidates for employing them for tuning purpose. In this paper, a novel tuning algorithm based on neural network estimated tuning parameters is presented. The key performance indicators are proactively monitored and fed as input to the Neural Network and the trained network estimates the suitable size of the buffer cache, shared pool and redo log buffer size. The tuner alters these tuning parameters using the estimated values using a rate change computing algorithm. The preliminary results show that the proposed method is effective in improving the query response tim...

  12. Control of the MKQA tuning and aperture kickers of the LHC

    CERN Document Server

    Barlow, R A; Pianfetti, J P; Senaj, V; Cattin, M; CERN. Geneva. TE Department

    2009-01-01

    The large hadron collider (LHC) at CERN has been equipped with four fast pulsed kicker magnets in RA43 situated at point 4 which are part of the measurement system for the tune and the dynamic aperture of the LHC beam (Beam 1 and Beam 2). For the tune measurement 'Q', the magnets will excite oscillations in part of the beam. This is achieved by means of a generator producing a 5 µs base half-sine pulse of 1.2 kA [1] amplitude, superimposed with a 3rd harmonic to produce a 2 µs flat top. A kick repetition rate of 2 Hz will be possible. To measure the dynamic aperture 'A' of the LHC at different beam energies, the same magnets will also be driven by a more powerful generator which produces a 43 µs base half-sine current pulse of 3.8 kA. For the 'A' mode a thyristor is used as switching element inside the generator. A final third mode named 'AC dipole' will rely on the beam being excited coherently at a frequency close but outside its Eigen-frequencies by an oscillating dipole field. The beam is expected to o...

  13. %191200 TUNE DEAFNESS [OMIM

    Lifescience Database Archive (English)

    Full Text Available TONE DEAFNESS FIELD TX DESCRIPTION Tune deafness, or congenital amusia, is a lifelong deficient in music per...retz et al., 2009). See 159300 for an opposite situation, that of musical perfect pitch. CLINICAL FEATURES P...icits, brain lesions, hearing loss, or socioaffective disturbances, and was exposed to music as a child. She... did not like to listen to music because it sounded to her like noise and induced stress. Detailed tests sho...hat fine-grained pitch perception is an essential component around which the musical system develops in a no

  14. Reversible hysteresis loop tuning

    Science.gov (United States)

    Berger, A.; Binek, Ch.; Margulies, D. T.; Moser, A.; Fullerton, E. E.

    2006-02-01

    We utilize antiferromagnetically coupled bilayer structures to magnetically tune hysteresis loop properties. Key element of this approach is the non-overlapping switching field distribution of the two magnetic layers that make up the system: a hard magnetic CoPtCrB layer (HL) and a soft magnetic CoCr layer (SL). Both layers are coupled antiferromagnetically through an only 0.6-nm-thick Ru interlayer. The non-overlapping switching field distribution allows the measurement of magnetization reversal in the SL at low fields while keeping the magnetization state of the HL unperturbed. Applying an appropriate high field or high field sequence changes the magnetic state of the HL, which then influences the SL magnetization reversal due to the interlayer coupling. In this way, the position and shape of the SL hysteresis loop can be changed or tuned in a fully reversible and highly effective manner. Here, we study specifically how the SL hysteresis loop characteristics change as we move the HL through an entire high field hysteresis loop sequence.

  15. Synthesis, structure, magnetic and transport properties of LnFeSb3 (Ln = Pr, Nd, Sm, Gd, and Tb)--tuning of anisotropic long-range magnetic order as a function of Ln.

    Science.gov (United States)

    Phelan, W Adam; Nguyen, Giang V; Karki, Amar B; Young, David P; Chan, Julia Y

    2010-07-28

    Single crystals of LnFeSb(3) (Ln = Pr, Nd, Sm, Gd, and Tb) have been grown from excess Sb flux. The crystal structure consists of (infinity)(2)[FeSb(2)] octahedra separated by layers of Ln atoms and nearly square planar nets of (infinity)(2)[Sb(2)]. These compounds are metallic and display anisotropic magnetic properties. Long-range antiferromagnetic order is observed in the Sm, Gd, and Tb samples when the magnetic field is applied along the crystallographic a-axis. Evidence of magnetic ordering in all the samples is observed for the field applied parallel to the layers. The magnetic properties are well-described by considering only the magnetic interactions between the Ln 4f moments, with no contribution from the Fe sublattice. Herein, we report the crystal growth, structure, magnetization, transport, and chemical stabilities of the title compounds.

  16. Widespread auditory deficits in tune deafness.

    Science.gov (United States)

    Jones, Jennifer L; Zalewski, Christopher; Brewer, Carmen; Lucker, Jay; Drayna, Dennis

    2009-02-01

    The goal of this study was to investigate auditory function in individuals with deficits in musical pitch perception. We hypothesized that such individuals have deficits in nonspeech areas of auditory processing. We screened 865 randomly selected individuals to identify those who scored poorly on the Distorted Tunes test (DTT), a measure of musical pitch recognition ability. Those who scored poorly were given a comprehensive audiologic examination, and those with hearing loss or other confounding audiologic factors were excluded from further testing. Thirty-five individuals with tune deafness constituted the experimental group. Thirty-four individuals with normal hearing and normal DTT scores, matched for age, gender, handedness, and education, and without overt or reported psychiatric disorders made up the normal control group. Individual and group performance for pure-tone frequency discrimination at 1000 Hz was determined by measuring the difference limen for frequency (DLF). Auditory processing abilities were assessed using tests of pitch pattern recognition, duration pattern recognition, and auditory gap detection. In addition, we evaluated both attention and short- and long-term memory as variables that might influence performance on our experimental measures. Differences between groups were evaluated statistically using Wilcoxon nonparametric tests and t-tests as appropriate. The DLF at 1000 Hz in the group with tune deafness was significantly larger than that of the normal control group. However, approximately one-third of participants with tune deafness had DLFs within the range of performance observed in the control group. Many individuals with tune deafness also displayed a high degree of variability in their intertrial frequency discrimination performance that could not be explained by deficits in memory or attention. Pitch and duration pattern discrimination and auditory gap-detection ability were significantly poorer in the group with tune deafness

  17. Tuning of Fuzzy PID Controllers

    DEFF Research Database (Denmark)

    Jantzen, Jan

    1998-01-01

    Since fuzzy controllers are nonlinear, it is more difficult to set the controller gains compared to proportional-integral-derivative (PID) controllers. This research paper proposes a design procedure and a tuning procedure that carries tuning rules from the PID domain over to fuzzy single......-loop controllers. The idea is to start with a tuned, conventional PID controller, replace it with an equivalent linear fuzzy controller, make the fuzzy controller nonlinear, and eventually fine-tune the nonlinear fuzzy controller. This is relevant whenever a PID controller is possible or already implemented....

  18. A Generalized Framework for Auto-tuning Stencil Computations

    Energy Technology Data Exchange (ETDEWEB)

    Kamil, Shoaib; Chan, Cy; Williams, Samuel; Oliker, Leonid; Shalf, John; Howison, Mark; Bethel, E. Wes; Prabhat,

    2009-05-01

    This work introduces a generalized framework for automatically tuning stencil computations to achieve superior performance on a broad range of multicore architectures. Stencil (nearest-neighbor) based kernels constitute the core of many important scientific applications involving block-structured grids. Auto-tuning systems search over optimization strategies to find the combination of tunable parameters that maximizes computational efficiency for a given algorithmic kernel. Although the auto-tuning strategy has been successfully applied to libraries, generalized stencil kernels are not amenable to packaging as libraries. Studied kernels in this work include both memory-bound kernels as well as a computation-bound bilateral filtering kernel. We introduce a generalized stencil auto-tuning framework that takes a straightforward Fortran expression of a stencil kernel and automatically generates tuned implementations of the kernel in C or Fortran to achieve performance portability across diverse computer architectures.

  19. Nanoplasmonics tuned ``click chemistry''

    Science.gov (United States)

    Tijunelyte, I.; Guenin, E.; Lidgi-Guigui, N.; Colas, F.; Ibrahim, J.; Toury, T.; Lamy de La Chapelle, M.

    2016-03-01

    Nanoplasmonics is a growing field of optical condensed matter science dedicated to optical phenomena at the nanoscale level in metal systems. Extensive research on noble metallic nanoparticles (NPs) has emerged within the last two decades due to their ability to keep the optical energy concentrated in the vicinity of NPs, in particular, the ability to create optical near-field enhancement followed by heat generation. We have exploited these properties in order to induce a localised ``click'' reaction in the vicinity of gold nanostructures under unfavourable experimental conditions. We demonstrate that this reaction can be controlled by the plasmonic properties of the nanostructures and we propose two physical mechanisms to interpret the observed plasmonic tuning of the ``click'' chemistry.Nanoplasmonics is a growing field of optical condensed matter science dedicated to optical phenomena at the nanoscale level in metal systems. Extensive research on noble metallic nanoparticles (NPs) has emerged within the last two decades due to their ability to keep the optical energy concentrated in the vicinity of NPs, in particular, the ability to create optical near-field enhancement followed by heat generation. We have exploited these properties in order to induce a localised ``click'' reaction in the vicinity of gold nanostructures under unfavourable experimental conditions. We demonstrate that this reaction can be controlled by the plasmonic properties of the nanostructures and we propose two physical mechanisms to interpret the observed plasmonic tuning of the ``click'' chemistry. Electronic supplementary information (ESI) available: NMR study on reaction initiation, SERS spectra and temperature calculations. See DOI: 10.1039/c5nr09018k

  20. Efficient receiver tuning using differential evolution strategies

    Science.gov (United States)

    Wheeler, Caleb H.; Toland, Trevor G.

    2016-08-01

    Differential evolution (DE) is a powerful and computationally inexpensive optimization strategy that can be used to search an entire parameter space or to converge quickly on a solution. The Kilopixel Array Pathfinder Project (KAPPa) is a heterodyne receiver system delivering 5 GHz of instantaneous bandwidth in the tuning range of 645-695 GHz. The fully automated KAPPa receiver test system finds optimal receiver tuning using performance feedback and DE. We present an adaptation of DE for use in rapid receiver characterization. The KAPPa DE algorithm is written in Python 2.7 and is fully integrated with the KAPPa instrument control, data processing, and visualization code. KAPPa develops the technologies needed to realize heterodyne focal plane arrays containing 1000 pixels. Finding optimal receiver tuning by investigating large parameter spaces is one of many challenges facing the characterization phase of KAPPa. This is a difficult task via by-hand techniques. Characterizing or tuning in an automated fashion without need for human intervention is desirable for future large scale arrays. While many optimization strategies exist, DE is ideal for time and performance constraints because it can be set to converge to a solution rapidly with minimal computational overhead. We discuss how DE is utilized in the KAPPa system and discuss its performance and look toward the future of 1000 pixel array receivers and consider how the KAPPa DE system might be applied.

  1. Plasmonic color tuning

    Science.gov (United States)

    Lee, Byoungho; Yun, Hansik; Lee, Seung-Yeol; Kim, Hwi

    2016-03-01

    In general, color filter is an optical component to permit the transmission of a specific color in cameras, displays, and microscopes. Each filter has its own unchangeable color because it is made by chemical materials such as dyes and pigments. Therefore, in order to express various colorful images in a display, one pixel should have three sub-pixels of red, green, and blue colors. Here, we suggest new plasmonic structure and method to change the color in a single pixel. It is comprised of a cavity and a metal nanoaperture. The optical cavity generally supports standing waves inside it, and various standing waves having different wavelength can be confined together in one cavity. On the other hand, although light cannot transmit sub-wavelength sized aperture, surface plasmons can propagate through the metal nanoaperture with high intensity due to the extraordinary transmission. If we combine the two structures, we can organize the spatial distribution of amplitudes according to wavelength of various standing waves using the cavity, and we can extract a light with specific wavelength and amplitude using the nanoaperture. Therefore, this cavity-aperture structure can simultaneously tune the color and intensity of the transmitted light through the single nanoaperture. We expect that the cavity-apertures have a potential for dynamic color pixels, micro-imaging system, and multiplexed sensors.

  2. Towards a robust phase locked loop tune feedback system

    CERN Document Server

    Jones, R; Luo, Y

    2005-01-01

    Attempts to introduce a reliable tune feedback loop at RHIC (BNL) [1] have been thwarted by two main problems, namely transition crossing and betatron coupling. The problem of transition crossing is a dynamic range problem, resulting from the increase in the revolution content of the observed signal as the bunch length becomes short and from the fast orbit changes that occur during transition. The dynamic range issue is being addressed by the development of a baseband tune measurement system [2] as part of the US LHC Accelerator Research Program (US-LARP). This paper will focus on the second problem, showing how a phase locked loop (PLL) tune measurement system can be used to continuously measure global betatron coupling, and in so doing allow for robust tune measurement and feedback in the presence of coupling.

  3. Amplitude dependent closest tune approach

    CERN Document Server

    Tomas Garcia, Rogelio; Franchi, Andrea; Maclean, Ewen Hamish; CERN. Geneva. ATS Department

    2016-01-01

    Recent observations in the LHC point to the existence of an amplitude dependent closest tune approach. However this dynamical behavior and its underlying mechanism remain unknown. This effect is highly relevant for the LHC as an unexpectedly closest tune approach varying with amplitude modifies the frequency content of the beam and, hence, the Landau damping. Furthermore the single particle stability would also be affected by this effect as it would modify how particles with varying amplitudes approach and cross resonances. We present analytic derivations that lead to a mechanism generating an amplitude dependent closest tune approach.

  4. Tuning fork tests: forgotten art.

    Science.gov (United States)

    Girgis, T F; Shambaugh, G E

    1988-01-01

    Four examples are cited in which tuning fork tests helped in proper selection of patients for surgery, after audiometric air and bone tests were equivocal or gave the wrong diagnostic and prognostic indication.

  5. Oracle SQL Tuning pocket Reference

    CERN Document Server

    Gurry, Mark

    2002-01-01

    One of the most important challenges faced by Oracle database administrators and Oracle developers is the need to tune SQL statements so that they execute efficiently. Poorly tuned SQL statements are one of the leading causes of substandard database performance and poor response time. SQL statements that perform poorly result in frustration for users, and can even prevent a company from serving its customers in a timely manner

  6. Disformally self-tuning gravity

    CERN Document Server

    Emond, William T

    2015-01-01

    We extend a previous self-tuning analysis of the most general scalar-tensor theory of gravity in four dimensions with second order field equations by considering a generalized coupling to the matter sector. Through allowing a disformal coupling to matter we are able to extend the Fab Four model and construct a new class of theories that are able to tune away the cosmological constant on Friedmann-Lemaitre-Robertson-Walker backgrounds.

  7. Disformally self-tuning gravity

    Science.gov (United States)

    Emond, William T.; Saffin, Paul M.

    2016-03-01

    We extend a previous self-tuning analysis of the most general scalar-tensor theory of gravity in four dimensions with second order field equations by considering a generalized coupling to the matter sector. Through allowing a disformal coupling to matter we are able to extend the Fab Four model and construct a new class of theories that are able to tune away the cosmological constant on Friedmann-Lemaitre-Robertson-Walker backgrounds.

  8. Adaptive Self-Tuning Networks

    Science.gov (United States)

    Knox, H. A.; Draelos, T.; Young, C. J.; Lawry, B.; Chael, E. P.; Faust, A.; Peterson, M. G.

    2015-12-01

    The quality of automatic detections from seismic sensor networks depends on a large number of data processing parameters that interact in complex ways. The largely manual process of identifying effective parameters is painstaking and does not guarantee that the resulting controls are the optimal configuration settings. Yet, achieving superior automatic detection of seismic events is closely related to these parameters. We present an automated sensor tuning (AST) system that learns near-optimal parameter settings for each event type using neuro-dynamic programming (reinforcement learning) trained with historic data. AST learns to test the raw signal against all event-settings and automatically self-tunes to an emerging event in real-time. The overall goal is to reduce the number of missed legitimate event detections and the number of false event detections. Reducing false alarms early in the seismic pipeline processing will have a significant impact on this goal. Applicable both for existing sensor performance boosting and new sensor deployment, this system provides an important new method to automatically tune complex remote sensing systems. Systems tuned in this way will achieve better performance than is currently possible by manual tuning, and with much less time and effort devoted to the tuning process. With ground truth on detections in seismic waveforms from a network of stations, we show that AST increases the probability of detection while decreasing false alarms.

  9. Differential Resonant Ring YIG Tuned Oscillator

    Science.gov (United States)

    Parrott, Ronald A.

    2010-01-01

    A differential SiGe oscillator circuit uses a resonant ring-oscillator topology in order to electronically tune the oscillator over multi-octave bandwidths. The oscillator s tuning is extremely linear, because the oscillator s frequency depends on the magnetic tuning of a YIG sphere, whose resonant frequency is equal to a fundamental constant times the DC magnetic field. This extremely simple circuit topology uses two coupling loops connecting a differential pair of SiGe bipolar transistors into a feedback configuration using a YIG tuned filter creating a closed-loop ring oscillator. SiGe device technology is used for this oscillator in order to keep the transistor s 1/f noise to an absolute minimum in order to achieve minimum RF phase noise. The single-end resonant ring oscillator currently has an advantage in fewer parts, but when the oscillation frequency is greater than 16 GHz, the package s parasitic behavior couples energy to the sphere and causes holes and poor phase noise performance. This is because the coupling to the YIG is extremely low, so that the oscillator operates at near the unloaded Q. With the differential resonant ring oscillator, the oscillation currents are just in the YIG coupling mechanisms. The phase noise is even better, and the physical size can be reduced to permit monolithic microwave integrated circuit oscillators. This invention is a YIG tuned oscillator circuit making use of a differential topology to simultaneously achieve an extremely broadband electronic tuning range and ultra-low phase noise. As a natural result of its differential circuit topology, all reactive elements, such as tuning stubs, which limit tuning bandwidth by contributing excessive open loop phase shift, have been eliminated. The differential oscillator s open-loop phase shift is associated with completely non-dispersive circuit elements such as the physical angle of the coupling loops, a differential loop crossover, and the high-frequency phase shift of the n

  10. Defending The Fallacy of Fine-Tuning

    CERN Document Server

    Stenger, Victor J

    2012-01-01

    In 2011, I published a popular-level book, The Fallacy of Fine-Tuning: Why the Universe is Not Designed for Us. It investigated a common claim found in contemporary religious literature that the parameters of physics and cosmology are so delicately balanced, so "fine-tuned," that any slight change and life in the universe would have been impossible. I concluded that while the precise form of life we find on Earth would not exist with slight changes in these parameters, some form of life could have evolved over a parameter range that is not infinitesimal, as often claimed. Postdoctoral fellow Luke Barnes has written a lengthy, highly technical review [arXiv:1112.4647] of the scientific literature on the fine-tuning problem. I have no significant disagreement with that literature and no prominent physicist or cosmologist has disputed my basic conclusions. Barnes does not invalidate these conclusions and misunderstands and misrepresents much of what is in the book.

  11. Simulation and Tuning of PID Controllers using Evolutionary Algorithms

    Directory of Open Access Journals (Sweden)

    K.R.S. Narayanan

    2012-10-01

    Full Text Available The Proportional Integral Derivative (PID controller is the most widely used control strategy in the Industry. The popularity of PID controllers can be attributed to their robust performance in a wide range of operating conditions and partly to their functional simplicity. The process of setting of PID controller can be determined as an optimization task. Over the years, use of intelligent strategies for tuning of these controllers has been growing. Biologically inspired evolutionary strategies have gained importance over other strategies because of their consistent performance over wide range of process models and their flexibility. The level control systems on Deaerator, Feed Water Heaters, and Condenser Hot well are critical to the proper operation of the units in Nuclear Power plants. For Precise control of level, available tuning technologies based on conventional optimization methods are found to be inadequate as these conventional methods are having limitations. To overcome the limitations, alternate tuning techniques based on Genetic Algorithm are emerging. This paper analyses the manual tuning techniques and compares the same with Genetic Algorithm tuning methods for tuning PID controllers for level control system and testing of the quality of process control in the simulation environment of PFBR Operator Training Simulator(OTS.

  12. 1THz synchronous tuning of two optical synthesizers

    Science.gov (United States)

    Neuhaus, Rudolf; Rohde, Felix; Benkler, Erik; Puppe, Thomas; Raab, Christoph; Unterreitmayer, Reinhard; Zach, Armin; Telle, Harald R.; Stuhler, Jürgen

    2016-04-01

    Single-frequency optical synthesizers (SFOS) provide an optical field with arbitrarily adjustable frequency and phase which is phase-coherently linked to a reference signal. Ideally, they combine the spectral resolution of narrow linewidth frequency stabilized lasers with the broad spectral coverage of frequency combs in a tunable fashion. In state-of-the-art SFOSs tuning across comb lines requires comb line order switching,1, 2 which imposes technical overhead with problems like forbidden frequency gaps or strong phase glitches. Conventional tunable lasers often tune over only tens of GHz before mode-hops occur. Here, we present a novel type of SFOSs, which relies on a serrodyne technique with conditional flyback,3 shifting the carrier frequency of the employed frequency comb without an intrusion into the comb generator. It utilizes a new continuously tunable diode laser that tunes mode-hop-free across the full gain spectrum of the integrated laser diode. We investigate the tuning behavior of two identical SFOSs that share a common reference, by comparing the phases of their output signals. Previously, we achieved phase-stable and cycle-slip free frequency tuning over 28.1 GHz with a maximum zero-to-peak phase deviation of 62 mrad4 when sharing a common comb generator. With the new continuously tunable lasers, the SFOSs tune synchronously across nearly 17800 comb lines (1 THz). The tuning range in this approach can be extended to the full bandwidth of the frequency comb and the 110 nm mode-hop-free tuning range of the diode laser.

  13. Tuning a Tetrahertz Wire Laser

    Science.gov (United States)

    Qin, Qi; Williams, Benjamin S.; Kumar, Sushil; Reno, John L.; Hu, Qing

    2009-01-01

    Tunable terahertz lasers are desirable in applications in sensing and spectroscopy because many biochemical species have strong spectral fingerprints at terahertz frequencies. Conventionally, the frequency of a laser is tuned in a similar manner to a stringed musical instrument, in which pitch is varied by changing the length of the string (the longitudinal component of the wave vector) and/ or its tension (the refractive index). However, such methods are difficult to implement in terahertz semiconductor lasers because of their poor outcoupling efficiencies. Here, we demonstrate a novel tuning mechanism based on a unique 'wire laser' device for which the transverse dimension w is much much less than lambda. Placing a movable object close to the wire laser manipulates a large fraction of the waveguided mode propagating outside the cavity, thereby tuning its resonant frequency. Continuous single-mode redshift and blueshift tuning is demonstrated for the same device by using either a dielectric or metallic movable object. In combination, this enables a frequency tuning of approximately equal to 137 GHz (3.6%) from a single laser device at approximately equal to 3.8 THz.

  14. The Fine-Tuning Argument

    CERN Document Server

    Landsman, Klaas

    2015-01-01

    Our laws of nature and our cosmos appear to be delicately fine-tuned for life to emerge, in way that seems hard to attribute to chance. In view of this, some have taken the opportunity to revive the scholastic Argument from Design, whereas others have felt the need to explain this apparent fine-tuning of the clockwork of the Universe by proposing the existence of a `Multiverse'. We analyze this issue from a sober perspective. Having reviewed the literature and having added several observations of our own, we conclude that cosmic fine-tuning supports neither Design nor a Multiverse, since both of these fail at an explanatory level as well as in a more quantitative context of Bayesian confirmation theory (although there might be other reasons to believe in these ideas, to be found in religion and in inflation and/or string theory, respectively). In fact, fine-tuning and Design even seem to be at odds with each other, whereas the inference from fine-tuning to a Multiverse only works if the latter is underwritten...

  15. Tuning quantum correlations with intracavity photonic crystals

    Energy Technology Data Exchange (ETDEWEB)

    Castro, Maria M. de; Gomila, Damia; Zambrini, Roberta [IFISC, Institute for Cross-Disciplinary Physics and Complex Systems (CSIC-UIB), Campus UIB, E-07122 Palma de Mallorca (Spain); Garcia-March, Miguel Angel [Department of Physics, Colorado School of Mines, Golden, Colorado 80401 (United States)

    2011-09-15

    We show how to tune quantum noise in nonlinear systems by means of periodic spatial modulation. We prove that the introduction of an intracavity photonic crystal in a multimode optical parametric oscillator inhibits and enhances light quantum fluctuations. Furthermore, it leads to a significant noise reduction in field quadratures, robustness of squeezing in a wider angular range, and spatial entanglement. These results have potential benefits for quantum imaging, metrology, and quantum information applications and suggest a control mechanism of fluctuations by spatial modulation of interest also in other nonlinear systems.

  16. Integrated unaligned resonant modulator tuning

    Energy Technology Data Exchange (ETDEWEB)

    Zortman, William A.; Lentine, Anthony L.

    2017-10-03

    Methods and systems for tuning a resonant modulator are disclosed. One method includes receiving a carrier signal modulated by the resonant modulator with a stream of data having an approximately equal number of high and low bits, determining an average power of the modulated carrier signal, comparing the average power to a predetermined threshold, and operating a tuning device coupled to the resonant modulator based on the comparison of the average power and the predetermined threshold. One system includes an input structure, a plurality of processing elements, and a digital control element. The input structure is configured to receive, from the resonant modulator, a modulated carrier signal. The plurality of processing elements are configured to determine an average power of the modulated carrier signal. The digital control element is configured to operate a tuning device coupled to the resonant modulator based on the average power of the modulated carrier signal.

  17. Automatic tuning of myoelectric prostheses.

    Science.gov (United States)

    Bonivento, C; Davalli, A; Fantuzzi, C; Sacchetti, R; Terenzi, S

    1998-07-01

    This paper is concerned with the development of a software package for the automatic tuning of myoelectric prostheses. The package core consists of Fuzzy Logic Expert Systems (FLES) that embody skilled operator heuristics in the tuning of prosthesis control parameters. The prosthesis system is an artificial arm-hand system developed at the National Institute of Accidents at Work (INAIL) laboratories. The prosthesis is powered by an electric motor that is controlled by a microprocessor using myoelectric signals acquired from skin-surface electrodes placed on a muscle in the residual limb of the subject. The software package, Microprocessor Controlled Arm (MCA) Auto Tuning, is a tool for aiding both INAIL expert operators and unskilled persons in the controller parameter tuning procedure. Prosthesis control parameter setup and subsequent recurrent adjustments are fundamental for the correct working of the prosthesis, especially when we consider that myoelectric parameters may vary greatly with environmental modifications. The parameter adjustment requires the end-user to go to the manufacturer's laboratory for the control parameters setup because, generally, he/she does not have the necessary knowledge and instruments to do this at home. However, this procedure is not very practical and involves a waste of time for the technicians and uneasiness for the clients. The idea behind the MCA Auto Tuning package consists in translating technician expertise into an FLES knowledge database. The software interacts through a user-friendly graphic interface with an unskilled user, who is guided through a step-by-step procedure in the prosthesis parameter tuning that emulates the traditional expert-aided procedure. The adoption of this program on a large scale may yield considerable economic benefits and improve the service quality supplied to the users of prostheses. In fact, the time required to set the prosthesis parameters are remarkably reduced, as is the technician

  18. Broad electrical tuning of plasmonic nanoantennas at visible frequencies

    Energy Technology Data Exchange (ETDEWEB)

    Hoang, Thang B. [Department of Physics, Duke University, Durham, North Carolina 27708 (United States); Center for Metamaterials and Integrated Plasmonics, Duke University, Durham, North Carolina 27708 (United States); Mikkelsen, Maiken H., E-mail: m.mikkelsen@duke.edu [Department of Physics, Duke University, Durham, North Carolina 27708 (United States); Center for Metamaterials and Integrated Plasmonics, Duke University, Durham, North Carolina 27708 (United States); Department of Electrical and Computer Engineering, Duke University, Durham, North Carolina 27708 (United States)

    2016-05-02

    We report an experimental demonstration of electrical tuning of plasmon resonances of optical nanopatch antennas over a wide wavelength range. The antennas consist of silver nanocubes separated from a gold film by a thin 8 nm polyelectrolyte spacer layer. By using ionic liquid and indium tin oxide coated glass as a top electrode, we demonstrate dynamic and reversible tuning of the plasmon resonance over 100 nm in the visible wavelength range using low applied voltages between −3.0 V and 2.8 V. The electrical potential is applied across the nanoscale gap causing changes in the gap thickness and dielectric environment which, in turn, modifies the plasmon resonance. The observed tuning range is greater than the full-width-at-half-maximum of the plasmon resonance, resulting in a tuning figure of merit of 1.05 and a tuning contrast greater than 50%. Our results provide an avenue to create active and reconfigurable integrated nanophotonic components for applications in optoelectronics and sensing.

  19. On the sensing and tuning of progressive structural vibration waves.

    Science.gov (United States)

    Minikes, Adi; Gabay, Ran; Bucher, Izhak; Feldman, Michael

    2005-09-01

    Progressive flexural waves can be generated only in finite structures by fine tuning the excitation and the boundary conditions. The tuning process eliminates the reflected waves arising from discontinuities and edge effects. This work presents and expands two new methods for the identification and tuning of traveling waves. One is a parametric method based on fitting an ellipse to the complex spatial amplitude distribution. The other is a nonparametric method based on the Hilbert transform providing a space-localized estimate. With these methods, an optimization-based tuning of transverse flexural waves in a one-dimensional structure, a vibrating beam, is developed. Existing methods are designed for a single frequency and are based on either combining two vibration modes or mechanical impedance matching. Such methods are limited to a designated excitation frequency determined by a specific configuration of the system. With the proposed methods, structural progressive waves can be generated for a wide range of frequencies under the same given system configuration and can be tuned in real time to accommodate changes in boundary conditions. An analytical study on the nature of the optimal excitation conditions has been carried out, revealing singular configurations. The experimental verification of the sensing and tuning methods is demonstrated on a dedicated laboratory prototype. The proposed methods are not confined to mechanical waves and present a comprehensive approach applicable for other physical wave phenomena.

  20. PID Tuning Using Extremum Seeking

    Energy Technology Data Exchange (ETDEWEB)

    Killingsworth, N; Krstic, M

    2005-11-15

    Although proportional-integral-derivative (PID) controllers are widely used in the process industry, their effectiveness is often limited due to poor tuning. Manual tuning of PID controllers, which requires optimization of three parameters, is a time-consuming task. To remedy this difficulty, much effort has been invested in developing systematic tuning methods. Many of these methods rely on knowledge of the plant model or require special experiments to identify a suitable plant model. Reviews of these methods are given in [1] and the survey paper [2]. However, in many situations a plant model is not known, and it is not desirable to open the process loop for system identification. Thus a method for tuning PID parameters within a closed-loop setting is advantageous. In relay feedback tuning [3]-[5], the feedback controller is temporarily replaced by a relay. Relay feedback causes most systems to oscillate, thus determining one point on the Nyquist diagram. Based on the location of this point, PID parameters can be chosen to give the closed-loop system a desired phase and gain margin. An alternative tuning method, which does not require either a modification of the system or a system model, is unfalsified control [6], [7]. This method uses input-output data to determine whether a set of PID parameters meets performance specifications. An adaptive algorithm is used to update the PID controller based on whether or not the controller falsifies a given criterion. The method requires a finite set of candidate PID controllers that must be initially specified [6]. Unfalsified control for an infinite set of PID controllers has been developed in [7]; this approach requires a carefully chosen input signal [8]. Yet another model-free PID tuning method that does not require opening of the loop is iterative feedback tuning (IFT). IFT iteratively optimizes the controller parameters with respect to a cost function derived from the output signal of the closed-loop system, see [9

  1. Actively controlled tuning of an external cavity diode laser by polarization spectroscopy.

    Science.gov (United States)

    Führer, Thorsten; Stang, Denise; Walther, Thomas

    2009-03-30

    We report on an universal method to achieve and sustain a large mode-hop free tuning range of an external cavity diode laser. By locking one of the resonators using a closed loop control based on polarization spectroscopy while tuning the laser we achieved mode-hop free tuning of up to 130 GHz with a non AR-coated, off-the-shelf laser diode.

  2. Tune Your Brown Clustering, Please

    DEFF Research Database (Denmark)

    Derczynski, Leon; Chester, Sean; Bøgh, Kenneth Sejdenfaden

    2015-01-01

    unexplored. Accordingly, we present information for practitioners on the behaviour of Brown clustering in order to assist hyper-parametre tuning, in the form of a theoretical model of Brown clustering utility. This model is then evaluated empirically in two sequence labelling tasks over two text types. We...

  3. Political Tunings of the Piano

    DEFF Research Database (Denmark)

    Højlund, Marie Koldkjær; Riis, Morten S.

    and appearance, we develop Morton’s understanding of the ambient to include an ambiguous play between content and frame. Reflected through the presented theoretical framework, the paper seeks to initiate a discussion of varied piano pieces by La Monte Young, Peter Ablinger and Richard James (Aphex Twin......) as unfolding the ambiguity of various political tunings of the piano....

  4. Haggling over the fine-tuning price of LEP

    Science.gov (United States)

    Chankowski, Piotr H.; Ellis, John; Olechowski, Marek; Pokorski, Stefan

    1999-04-01

    We amplify previous discussions of the fine-tuning price to be paid by supersymmetric models in the light of LEP data. The whole range of tan β is discussed, including large values. In the minimal supergravity model with universal gaugino and scalar masses, a small fine-tuning price is possible only for intermediate values of tan β and for a small range of superpartner masses. Moreover, the fine-tuning price in this region is significantly higher if we require β-τ Yukawacoupling unification. We interpret the significant increase after LEP of the fine-tuning price in the minimal supergravity model as a message for theory and not for the experiment. For possible choices of low-energy parameters in the MSSM consistent with present experimental constraints and, optionally, with some other theoretical assumptions such as ifb-τ Yukawa-coupling unification, a measure of the amount of fine tuning becomes an interesting criterion for the naturalness of various theoretical models for mass terms in the MSSM Lagrangian. In particular, we emphasize that the fine-tuning price will depend on the actual solution to the μ problem. We illustrate the relevance of this fact by considering a simple ansatz of linear dependence of μ on M {1}/{2} or A0, showing that big price reductions are obtained in such cases. Significant price reductions are also obtained for large tan β if non-universal soft Higgs mass parameters are allowed. We also study input relations between MSSM parameters suggested in some interpretations of string theory: the price may depend significantly on these inputs, potentially providing guidance for building string models. However, in the available models the fine-tuning price may not be reduced significantly.

  5. Tuned Inhibitory Responses in Binocular Natural Images

    Directory of Open Access Journals (Sweden)

    R Goutcher

    2013-10-01

    Full Text Available Binocular neurons in primary visual cortex are typically categorised as either Near, Far, Tuned Excitatory (TE or Tuned Inhibitory (TI cells (Poggio & Fischer, 1977, J. Neurophysiol., 40, 1392-1405. Both TI and TE responses may be approximated through differing arrangements of the binocular energy model (Ohzawa, De Angelis & Freeman, 1990, Science, 249, 1037-1041, with TE neurons responding to instances of binocular correlation, and TI neurons responding to a lack of correlation. Differences in the inter-ocular phase or position of receptive fields allow model TE cells to be used for the measurement of binocular disparity. Previous research (Hibbard, 2008, Vision Research, 48, 1427-1439 has examined the responses of these disparity tuned TE neurons to binocular natural images. However, the responses of TI neurons to such images are not clear. We examined these TI responses for a set of binocular natural images, and compared them to responses for random-dot stereograms (RDSs. TI neuron responses were modelled by placing left and right eye receptive fields in anti-phase arrangement. In addition, TI responses were normalised by monocular energy. This provides a response with a range of ±1, with a value of +1 indicating that two image regions are anti-correlated. TI responses were generally negative for both RDSs and natural images. For binocular natural images, positive TI responses were found for a small proportion of units. Typically, positive TI responses were found when monocular energy was low, occurred across all orientation channels, and increased in prevalence at lower spatial frequencies. Positive responses were clustered around object edges, suggesting a functional role for TI neurons in the detection of depth boundaries.

  6. Summary of ATLAS Pythia 8 tunes

    CERN Document Server

    The ATLAS collaboration

    2012-01-01

    We summarize the latest ATLAS Pythia 8 minimum bias and underlying event tunes. The Pythia 8 MPI tunes in this note have been constructed for nine different PDFs, making use of a new x-dependent hadronic matter distribution model.

  7. Self-tuning regulators. [adaptive control research

    Science.gov (United States)

    Astrom, K. J.

    1975-01-01

    The results of a research project are discussed for self-tuning regulators for active control. An algorithm for the self-tuning regulator is described as being stochastic, nonlinear, time variable, and not trivial.

  8. ELASTIC: A Large Scale Dynamic Tuning Environment

    Directory of Open Access Journals (Sweden)

    Andrea Martínez

    2014-01-01

    Full Text Available The spectacular growth in the number of cores in current supercomputers poses design challenges for the development of performance analysis and tuning tools. To be effective, such analysis and tuning tools must be scalable and be able to manage the dynamic behaviour of parallel applications. In this work, we present ELASTIC, an environment for dynamic tuning of large-scale parallel applications. To be scalable, the architecture of ELASTIC takes the form of a hierarchical tuning network of nodes that perform a distributed analysis and tuning process. Moreover, the tuning network topology can be configured to adapt itself to the size of the parallel application. To guide the dynamic tuning process, ELASTIC supports a plugin architecture. These plugins, called ELASTIC packages, allow the integration of different tuning strategies into ELASTIC. We also present experimental tests conducted using ELASTIC, showing its effectiveness to improve the performance of large-scale parallel applications.

  9. Farm Tractor Tune-Up and Service Specifications.

    Science.gov (United States)

    Bryant, J. G.; And Others

    Tune-up and service specifications for 10 major tractor manufacturers are presented in the handbook. In addition, the following tables are included: (1) spark plug heat-range comparisons, (2) freezing protection, (3) pressures for farm tractor tires, (4) use of calcium chloride for liquid weighting, (5) comparisons of American Petroleum Institute…

  10. Tuning the Gap of a Superconducting Flux Qubit

    NARCIS (Netherlands)

    Paauw, F.G.; Fedorov, A.; Harmans, C.J.P.M.; Mooij, J.E.

    2009-01-01

    We experimentally demonstrate the in situ tunability of the minimum energy splitting (gap) of a superconducting flux qubit by means of an additional flux loop. Pulses applied via a local control line allow us to tune the gap over a range of several GHz on a nanosecond time scale. The strong flux sen

  11. Precision and Fast Wavelength Tuning of a Dynamically Phase-Locked Widely-Tunable Laser

    Science.gov (United States)

    Numata, Kenji; Chen, Jeffrey R.; Wu, Stewart T.

    2012-01-01

    We report a precision and fast wavelength tuning technique demonstrated for a digital-supermode distributed Bragg reflector laser. The laser was dynamically offset-locked to a frequency-stabilized master laser using an optical phase-locked loop, enabling precision fast tuning to and from any frequencies within a 40-GHz tuning range. The offset frequency noise was suppressed to the statically offset-locked level in less than 40 s upon each frequency switch, allowing the laser to retain the absolute frequency stability of the master laser. This technique satisfies stringent requirements for gas sensing lidars and enables other applications that require such well-controlled precision fast tuning.

  12. Data Driven Tuning of Inventory Controllers

    DEFF Research Database (Denmark)

    Huusom, Jakob Kjøbsted; Santacoloma, Paloma Andrade; Poulsen, Niels Kjølstad

    2007-01-01

    A systematic method for criterion based tuning of inventory controllers based on data-driven iterative feedback tuning is presented. This tuning method circumvent problems with modeling bias. The process model used for the design of the inventory control is utilized in the tuning...... as an approximation to reduce time required on experiments. The method is illustrated in an application with a multivariable inventory control implementation on a four tank system....

  13. The dependence of the dynamic aperture on the tune in RHIC

    Energy Technology Data Exchange (ETDEWEB)

    Parzen, G.

    1992-01-01

    This note studies the dependence of the dynamic aperture on the choice of the operating tune {nu}{sub x}, {nu}{sub y} in RHIC. Tracking studies for 1000 turns were done over the tune range {nu}{sub x} {approx equal} {nu}{sub y} = 28 to {nu}{sub x} {approx equal} {nu}{sub y} = 29.5. It was found that in each tune interval {Delta}{nu} = 0.5, e.g. {nu} = 28.5 to {nu} = 29, the dynamic aperture as a function of the tune has 5 peaks, each of which is a possible operating point. Each of these possible operating points is in a tune region free of imperfection resonances of tenth order or less, and the width of this tune region ranges from {Delta}{nu} = 0.022 to {Delta}{nu} = 0.036. Operating tunes near integer values of {nu}, which appear desirable because of the relatively large tune interval free of imperfection resonances of 10th order or less, may not be desirable because of the lower dynamic aperture in this region. Operating near integer tunes may not be desirable for heavy ions like Au, but may be desirable for the lighter ions which do not experience a large transverse growth due to intrabeam scattering. If a loss in dynamic aperture of 2 mm is regarded as significant, then the tune range of {nu} = 28 to {nu} = 28.5 does not appear as attractive as the tune range {nu} = 28.5 to {nu} = 29.5.

  14. The dependence of the dynamic aperture on the tune in RHIC

    Energy Technology Data Exchange (ETDEWEB)

    Parzen, G.

    1992-08-01

    This note studies the dependence of the dynamic aperture on the choice of the operating tune {nu}{sub x}, {nu}{sub y} in RHIC. Tracking studies for 1000 turns were done over the tune range {nu}{sub x} {approx_equal} {nu}{sub y} = 28 to {nu}{sub x} {approx_equal} {nu}{sub y} = 29.5. It was found that in each tune interval {Delta}{nu} = 0.5, e.g. {nu} = 28.5 to {nu} = 29, the dynamic aperture as a function of the tune has 5 peaks, each of which is a possible operating point. Each of these possible operating points is in a tune region free of imperfection resonances of tenth order or less, and the width of this tune region ranges from {Delta}{nu} = 0.022 to {Delta}{nu} = 0.036. Operating tunes near integer values of {nu}, which appear desirable because of the relatively large tune interval free of imperfection resonances of 10th order or less, may not be desirable because of the lower dynamic aperture in this region. Operating near integer tunes may not be desirable for heavy ions like Au, but may be desirable for the lighter ions which do not experience a large transverse growth due to intrabeam scattering. If a loss in dynamic aperture of 2 mm is regarded as significant, then the tune range of {nu} = 28 to {nu} = 28.5 does not appear as attractive as the tune range {nu} = 28.5 to {nu} = 29.5.

  15. Tuning Properties in Silver Clusters

    KAUST Repository

    Joshi, Chakra Prasad

    2015-07-09

    The properties of Ag nanoclusters are not as well understood as those of their more precious Au cousins. However, a recent surge in the exploration of strategies to tune the physicochemical characteristics of Ag clusters addresses this imbalance, leading to new insights into their optical, luminescence, crystal habit, metal-core, ligand-shell and environmental properties. In this Perspective, we provide an overview of the latest strategies along with a brief introduction of the theoretical framework necessary to understand the properties of silver nanoclusters and the basis for their tuning. The advances in cluster research and the future prospects presented in this Perspective will eventually guide the next large systematic study of nanoclusters, resulting in a single collection of data similar to the periodic table of elements.

  16. IMC based robust PID controller tuning for disturbance rejection

    Institute of Scientific and Technical Information of China (English)

    Mohammad Shamsuzzoha

    2016-01-01

    It is well-known that the IMC-PID controller tuning gives fast and improved set point response but slow disturbance rejection. A modification has been proposed in IMC-PID tuning rule for the improved disturbance rejection. For the modified IMC-PID tuning rule, a method has been developed to obtain the IMC-PID setting in closed-loop mode without acquiring detailed information of the process. The proposed method is based on the closed-loop step set point experiment using a proportional only controller with gainKc0. It is the direct approach to find the PID controller setting similar to classical Ziegler-Nichols closed-loop method. Based on simulations of a wide range of first-order with delay processes, a simple correlation has been derived to obtain the modified IMC-PID controller settings from closed-loop experiment. In this method, controller gain is a function of the overshoot obtained in the closed loop set point experiment. The integral and derivative time is mainly a function of the time to reach the first peak (overshoot). Simulation has been conducted for the broad class of processes and the controllers were tuned to have the same degree of robustness by measuring the maximum sensitivity, Ms, in order to obtain a reasonable comparison. The PID controller settings obtained in the proposed tuning method show better performance and robustness with other two-step tuning methods for the broad class of processes. It has also been applied to temperature control loop in distillation column model. The result has been compared to the open loop tuning method where it gives robust and fast response.

  17. Broader visual orientation tuning in patients with schizophrenia

    Directory of Open Access Journals (Sweden)

    Ariel eRokem

    2011-11-01

    Full Text Available Reduced gamma-aminobutyric acid (GABA levels in cerebral cortex are thought to contribute to information processing deficits in patients with schizophrenia (SZ, and we have previously reported lower in vivo GABA levels in the visual cortex of patients with SZ. GABA-mediated inhibition plays a role in sharpening orientation tuning of visual cortical neurons. Therefore, we predicted that tuning for visual stimulus orientation would be wider in SZ. We measured orientation tuning with a psychophysical procedure in which subjects performed a target detection task of a low-contrast oriented grating, following adaptation to a high-contrast grating. Contrast detection thresholds were determined for a range of adapter-target orientation offsets. For both SZ and healthy controls, contrast thresholds decreased as orientation offset increased, suggesting that this tuning curve reflects the selectivity of visual cortical neurons for stimulus orientation. After accounting for generalized deficits in task performance in SZ, there was no difference between patients and controls for detection of target stimuli having either the same orientation as the adapter or orientations far from the adapter. However, patients’ thresholds were significantly higher for intermediate adapter-target offsets. In addition, the mean width parameter of a Gaussian fit to the psychophysical orientation tuning curves was significantly larger for the patient group. We also present preliminary data relating visual cortical GABA levels, as measured with magnetic resonance spectroscopy, and orientation tuning width. These results suggest that our finding of broader orientation tuning in SZ may be due to diminished visual cortical GABA levels.

  18. On the MSSM Higgsino mass and fine tuning

    CERN Document Server

    Ross, Graham G.

    2016-08-10

    It is often argued that low fine tuning in the MSSM necessarily requires a rather light Higgsino. In this note we show that this need not be the case when a more complete set of soft SUSY breaking mass terms are included. In particular an Higgsino mass term, that correlates the $\\mu-$term contribution with the soft SUSY-breaking Higgsino masses, significantly reduces the fine tuning even for Higgsinos in the TeV mass range where its relic abundance means it can make up all the dark matter.

  19. On the MSSM Higgsino mass and fine tuning

    Science.gov (United States)

    Ross, Graham G.; Schmidt-Hoberg, Kai; Staub, Florian

    2016-08-01

    It is often argued that low fine tuning in the MSSM necessarily requires a rather light Higgsino. In this note we show that this need not be the case when a more complete set of soft SUSY breaking mass terms are included. In particular an Higgsino mass term, that correlates the μ-term contribution with the soft SUSY-breaking Higgsino masses, significantly reduces the fine tuning even for Higgsinos in the TeV mass range where its relic abundance means it can make up all the dark matter.

  20. Thermally tunable silicon racetrack resonators with ultralow tuning power.

    Science.gov (United States)

    Dong, Po; Qian, Wei; Liang, Hong; Shafiiha, Roshanak; Feng, Dazeng; Li, Guoliang; Cunningham, John E; Krishnamoorthy, Ashok V; Asghari, Mehdi

    2010-09-13

    We present thermally tunable silicon racetrack resonators with an ultralow tuning power of 2.4 mW per free spectral range. The use of free-standing silicon racetrack resonators with undercut structures significantly enhances the tuning efficiency, with one order of magnitude improvement of that for previously demonstrated thermo-optic devices without undercuts. The 10%-90% switching time is demonstrated to be ~170 µs. Such low-power tunable micro-resonators are particularly useful as multiplexing devices and wavelength-tunable silicon microcavity modulators.

  1. Distributed chaos tuned to large scale coherent motions in turbulence

    CERN Document Server

    Bershadskii, A

    2016-01-01

    It is shown, using direct numerical simulations and laboratory experiments data, that distributed chaos is often tuned to large scale coherent motions in anisotropic inhomogeneous turbulence. The examples considered are: fully developed turbulent boundary layer (range of coherence: $14 < y^{+} < 80$), turbulent thermal convection (in a horizontal cylinder), and Cuette-Taylor flow. Two ways of the tuning have been described: one via fundamental frequency (wavenumber) and another via subharmonic (period doubling). For the second way the large scale coherent motions are a natural component of distributed chaos. In all considered cases spontaneous breaking of space translational symmetry is accompanied by reflexional symmetry breaking.

  2. On the MSSM Higgsino mass and fine tuning

    Energy Technology Data Exchange (ETDEWEB)

    Ross, Graham G. [Oxford Univ. (United Kingdom). Rudof Peierls Centre for Theoretical Physics; Schmidt-Hoberg, Kai [Deutsches Elektronen-Synchrotron (DESY), Hamburg (Germany); Staub, Florian [CERN, Geneva (Switzerland). Theoretical Physics Dept.

    2016-03-15

    It is often argued that low fine tuning in the MSSM necessarily requires a rather light Higgsino. In this note we show that this need not be the case when a more complete set of soft SUSY breaking mass terms are included. In particular an Higgsino mass term, that correlates the μ-term contribution with the soft SUSY-breaking Higgsino masses, significantly reduces the fine tuning even for Higgsinos in the TeV mass range where its relic abundance means it can make up all the dark matter.

  3. On the MSSM Higgsino mass and fine tuning

    Energy Technology Data Exchange (ETDEWEB)

    Ross, Graham G., E-mail: g.ross1@physics.ox.ac.uk [Rudolf Peierls Centre for Theoretical Physics, University of Oxford, 1 Keble Road, Oxford OX1 3NP (United Kingdom); Schmidt-Hoberg, Kai, E-mail: kai.schmidt-hoberg@desy.de [Deutsches Elektronen-Synchrotron DESY, Notkestraße 85, D-22607 Hamburg (Germany); Staub, Florian, E-mail: florian.staub@cern.ch [Theoretical Physics Department, CERN, Geneva (Switzerland)

    2016-08-10

    It is often argued that low fine tuning in the MSSM necessarily requires a rather light Higgsino. In this note we show that this need not be the case when a more complete set of soft SUSY breaking mass terms are included. In particular an Higgsino mass term, that correlates the μ-term contribution with the soft SUSY-breaking Higgsino masses, significantly reduces the fine tuning even for Higgsinos in the TeV mass range where its relic abundance means it can make up all the dark matter.

  4. Practical design of a nonlinear tuned vibration absorber

    DEFF Research Database (Denmark)

    Grappasonni, C.; Habib, G.; Detroux, T.

    2014-01-01

    The aim of the paper is to develop a new nonlinear tuned vibration absorber (NLTVA) capable of mitigating the vibrations of nonlinear systems which are known to exhibit frequency-energy-dependent oscillations. A nonlinear generalization of Den Hartog's equal-peak method is proposed to ensure equal...... peaks in the nonlinear frequency response for a large range of forcing amplitudes. An analytical tuning procedure is developed and provides the load-deflection characteristic of the NLTVA. Based on this prescribed relation, the NLTVA design is performed by two different approaches, namely thanks to (i...

  5. Tuned mass absorber on a flexible structure

    DEFF Research Database (Denmark)

    Krenk, Steen; Høgsberg, Jan Becker

    2014-01-01

    The classic design of a tuned mass absorber is based on a simple two-mass analogy in which the tuned mass is connected to the structural mass with a spring and a viscous damper. In a flexible multi-degree-of-freedom structure the tuned mass absorber is typically introduced to provide damping of a...

  6. A tuning algorithm for model predictive controllers based on genetic algorithms and fuzzy decision making.

    Science.gov (United States)

    van der Lee, J H; Svrcek, W Y; Young, B R

    2008-01-01

    Model Predictive Control is a valuable tool for the process control engineer in a wide variety of applications. Because of this the structure of an MPC can vary dramatically from application to application. There have been a number of works dedicated to MPC tuning for specific cases. Since MPCs can differ significantly, this means that these tuning methods become inapplicable and a trial and error tuning approach must be used. This can be quite time consuming and can result in non-optimum tuning. In an attempt to resolve this, a generalized automated tuning algorithm for MPCs was developed. This approach is numerically based and combines a genetic algorithm with multi-objective fuzzy decision-making. The key advantages to this approach are that genetic algorithms are not problem specific and only need to be adapted to account for the number and ranges of tuning parameters for a given MPC. As well, multi-objective fuzzy decision-making can handle qualitative statements of what optimum control is, in addition to being able to use multiple inputs to determine tuning parameters that best match the desired results. This is particularly useful for multi-input, multi-output (MIMO) cases where the definition of "optimum" control is subject to the opinion of the control engineer tuning the system. A case study will be presented in order to illustrate the use of the tuning algorithm. This will include how different definitions of "optimum" control can arise, and how they are accounted for in the multi-objective decision making algorithm. The resulting tuning parameters from each of the definition sets will be compared, and in doing so show that the tuning parameters vary in order to meet each definition of optimum control, thus showing the generalized automated tuning algorithm approach for tuning MPCs is feasible.

  7. Cosine tuning minimizes motor errors.

    Science.gov (United States)

    Todorov, Emanuel

    2002-06-01

    Cosine tuning is ubiquitous in the motor system, yet a satisfying explanation of its origin is lacking. Here we argue that cosine tuning minimizes expected errors in force production, which makes it a natural choice for activating muscles and neurons in the final stages of motor processing. Our results are based on the empirically observed scaling of neuromotor noise, whose standard deviation is a linear function of the mean. Such scaling predicts a reduction of net force errors when redundant actuators pull in the same direction. We confirm this prediction by comparing forces produced with one versus two hands and generalize it across directions. Under the resulting neuromotor noise model, we prove that the optimal activation profile is a (possibly truncated) cosine--for arbitrary dimensionality of the workspace, distribution of force directions, correlated or uncorrelated noise, with or without a separate cocontraction command. The model predicts a negative force bias, truncated cosine tuning at low muscle cocontraction levels, and misalignment of preferred directions and lines of action for nonuniform muscle distributions. All predictions are supported by experimental data.

  8. Eighth-Grade Violinists' Instrument Tuning Ability: A Comparison of Pitch Perception and Tuning Accuracy

    Science.gov (United States)

    Hopkins, Michael T.

    2015-01-01

    The purpose of this study was to explore the relationship between eighth-grade violinists' pitch perception and instrument tuning skill. The perceptual task was a researcher-developed computer-based Violin Tuning Perception Test. The instrument tuning task involved tuning two violins, one mistuned flat and the other mistuned sharp. Participants (N…

  9. Oracle SQL tuning with Oracle SQLTXPLAIN

    CERN Document Server

    Charalambides, Stelios

    2013-01-01

    Oracle SQL Tuning with SQLTXPLAIN is a practical guide to SQL tuning the way Oracle's own experts do it, using a freely downloadable tool called SQLTXPLAIN. Using this simple tool you'll learn how to tune even the most complex SQL, and you'll learn to do it quickly, without the huge learning curve usually associated with tuning as a whole.  Firmly based in real world problems, this book helps you reclaim system resources and avoid the most common bottleneck in overall performance, badly tuned SQL.  You'll learn how the optimizer works, how to take advantage of its latest features, and when it'

  10. New tuning method for PID controller.

    Science.gov (United States)

    Shen, Jing-Chung

    2002-10-01

    In this paper, a tuning method for proportional-integral-derivative (PID) controller and the performance assessment formulas for this method are proposed. This tuning method is based on a genetic algorithm based PID controller design method. For deriving the tuning formula, the genetic algorithm based design method is applied to design PID controllers for a variety of processes. The relationship between the controller parameters and the parameters that characterize the process dynamics are determined and the tuning formula is then derived. Using simulation studies, the rules for assessing the performance of a PID controller tuned by the proposed method are also given. This makes it possible to incorporate the capability to determine if the PID controller is well tuned or not into an autotuner. An autotuner based on this new tuning method and the corresponding performance assessment rules is also established. Simulations and real-time experimental results are given to demonstrate the effectiveness and usefulness of these formulas.

  11. Tuning exchange interactions in organometallic semiconductors

    Science.gov (United States)

    Rawat, Naveen; Manning, Lane W.; Hua, Kim-Ngan; Headrick, Randall L.; Cherian, Judy G.; Bishop, Michael M.; McGill, Stephen A.; Furis, Madalina I.

    2015-09-01

    Organic semiconductors are emerging as a leading area of research as they are expected to overcome limitations of inorganic semiconductor devices for certain applications where low cost manufacturing, device transparency in the visible range or mechanical flexibility are more important than fast switching times. Solution processing methods produce thin films with millimeter sized crystalline grains at very low cost manufacturing prices, ideally suited for optical spectroscopy investigations of long range many-body effects in organic systems. To this end, we synthesized an entire family of organosoluble 3-d transition metal Pc's and successfully employed a novel solution-based pen-writing deposition technique to fabricate long range ordered thin films of mixtures of metal-free (H2Pc) molecule and organometallic phthalocyanines (MPc's). Our previous studies on the parent MPc crystalline thin films identified different electronic states mediating exchange interactions in these materials. This understanding of spin-dependent exchange interaction between delocalized π-electrons with unpaired d spins enabled the further tuning of these interactions by mixing CoPc and H2Pc in different ratios ranging from 1:1 to 1000:1 H2Pc:MPc. The magnitude of the exchange is also tunable as a function of the average distance between unpaired spins in these materials. Furthermore, high magnetic field (B materials.

  12. Generation of spike latency tuning by thalamocortical circuits in auditory cortex.

    Science.gov (United States)

    Zhou, Yi; Mesik, Lukas; Sun, Yujiao J; Liang, Feixue; Xiao, Zhongju; Tao, Huizhong W; Zhang, Li I

    2012-07-18

    In many sensory systems, the latency of spike responses of individual neurons is found to be tuned for stimulus features and proposed to be used as a coding strategy. Whether the spike latency tuning is simply relayed along sensory ascending pathways or generated by local circuits remains unclear. Here, in vivo whole-cell recordings from rat auditory cortical neurons in layer 4 revealed that the onset latency of their aggregate thalamic input exhibited nearly flat tuning for sound frequency, whereas their spike latency tuning was much sharper with a broadly expanded dynamic range. This suggests that the spike latency tuning is not simply inherited from the thalamus, but can be largely reconstructed by local circuits in the cortex. Dissecting of thalamocortical circuits and neural modeling further revealed that broadly tuned intracortical inhibition prolongs the integration time for spike generation preferentially at off-optimal frequencies, while sharply tuned intracortical excitation shortens it selectively at the optimal frequency. Such push and pull mechanisms mediated likely by feedforward excitatory and inhibitory inputs respectively greatly sharpen the spike latency tuning and expand its dynamic range. The modulation of integration time by thalamocortical-like circuits may represent an efficient strategy for converting information spatially coded in synaptic strength to temporal representation.

  13. Selective tuning of high-Q silicon photonic crystal nanocavities via laser-assisted local oxidation

    CERN Document Server

    Chen, Charlton J; Gu, Tingyi; McMillan, James F; Yu, Mingbin; Lo, Guo-Qiang; Kwong, Dim-Lee; Wong, Chee Wei

    2011-01-01

    We examine the cavity resonance tuning of high-Q silicon photonic crystal heterostructures by localized laser-assisted thermal oxidation using a 532 nm continuous wave laser focused to a 2.5 mm radius spot-size. The total shift is consistent with the parabolic rate law. A tuning range of up to 8.7 nm is achieved with ~ 30 mW laser powers. Over this tuning range, the cavity Q decreases from 3.2\\times10^5 to 1.2\\times10^5. Numerical simulations model the temperature distributions in the silicon photonic crystal membrane and the cavity resonance shift from oxidation.

  14. POET: Parameterized Optimization for Empirical Tuning

    Energy Technology Data Exchange (ETDEWEB)

    Yi, Q; Seymour, K; You, H; Vuduc, R; Quinlan, D

    2007-01-29

    The excessive complexity of both machine architectures and applications have made it difficult for compilers to statically model and predict application behavior. This observation motivates the recent interest in performance tuning using empirical techniques. We present a new embedded scripting language, POET (Parameterized Optimization for Empirical Tuning), for parameterizing complex code transformations so that they can be empirically tuned. The POET language aims to significantly improve the generality, flexibility, and efficiency of existing empirical tuning systems. We have used the language to parameterize and to empirically tune three loop optimizations-interchange, blocking, and unrolling-for two linear algebra kernels. We show experimentally that the time required to tune these optimizations using POET, which does not require any program analysis, is significantly shorter than that when using a full compiler-based source-code optimizer which performs sophisticated program analysis and optimizations.

  15. Tuning of MEMS Gyroscope using Evolutionary Algorithm and "Switched Drive-Angle" Method

    Science.gov (United States)

    Keymeulen, Didier; Ferguson, Michael I.; Breuer, Luke; Peay, Chris; Oks, Boris; Cheng, Yen; Kim, Dennis; MacDonald, Eric; Foor, David; Terrile, Rich; Yee, Karl

    2006-01-01

    We propose a tuning method for Micro-Electro-Mechanical Systems (MEMS) gyroscopes based on evolutionary computation that has the capacity to efficiently increase the sensitivity of MEMS gyroscopes through tuning and, furthermore, to find the optimally tuned configuration for this state of increased sensitivity. We present the results of an experiment to determine the speed and efficiency of an evolutionary algorithm applied to electrostatic tuning of MEMS micro gyros. The MEMS gyro used in this experiment is a pyrex post resonator gyro (PRG) in a closed-loop control system. A measure of the quality of tuning is given by the difference in resonant frequencies, or frequency split, for the two orthogonal rocking axes. The current implementation of the closed-loop platform is able to measure and attain a relative stability in the sub-millihertz range, leading to a reduction of the frequency split to less than 100 mHz.

  16. Tuning innate immunity by translation.

    Science.gov (United States)

    Rauscher, Robert; Ignatova, Zoya

    2015-12-01

    In multicellular organisms, the epithelia is a contact surface with the surrounding environment and is exposed to a variety of adverse biotic (pathogenic) and abiotic (chemical) factors. Multi-layered pathways that operate on different time scales have evolved to preserve cellular integrity and elicit stress-specific response. Several stress-response programs are activated until a complete elimination of the stress is achieved. The innate immune response, which is triggered by pathogenic invasion, is rather harmful when active over a prolonged time, thus the response follows characteristic oscillatory trajectories. Here, we review different translation programs that function to precisely fine-tune the time at which various components of the innate immune response dwell between active and inactive. We discuss how different pro-inflammatory pathways are co-ordinated to temporally offset single reactions and to achieve an optimal balance between fighting pathogens and being less harmful for healthy cells.

  17. Contrast adaptation contributes to contrast-invariance of orientation tuning of primate V1 cells.

    Directory of Open Access Journals (Sweden)

    Lionel G Nowak

    Full Text Available BACKGROUND: Studies in rodents and carnivores have shown that orientation tuning width of single neurons does not change when stimulus contrast is modified. However, in these studies, stimuli were presented for a relatively long duration (e. g., 4 seconds, making it possible that contrast adaptation contributed to contrast-invariance of orientation tuning. Our first purpose was to determine, in marmoset area V1, whether orientation tuning is still contrast-invariant with the stimulation duration is comparable to that of a visual fixation. METHODOLOGY/PRINCIPAL FINDINGS: We performed extracellular recordings and examined orientation tuning of single-units using static sine-wave gratings that were flashed for 200 msec. Sixteen orientations and three contrast levels, representing low, medium and high values in the range of effective contrasts for each neuron, were randomly intermixed. Contrast adaptation being a slow phenomenon, cells did not have enough time to adapt to each contrast individually. With this stimulation protocol, we found that the tuning width obtained at intermediate contrast was reduced to 89% (median, and that at low contrast to 76%, of that obtained at high contrast. Therefore, when probed with briefly flashed stimuli, orientation tuning is not contrast-invariant in marmoset V1. Our second purpose was to determine whether contrast adaptation contributes to contrast-invariance of orientation tuning. Stationary gratings were presented, as previously, for 200 msec with randomly varying orientations, but the contrast was kept constant within stimulation blocks lasting >20 sec, allowing for adaptation to the single contrast in use. In these conditions, tuning widths obtained at low contrast were still significantly less than at high contrast (median 85%. However, tuning widths obtained with medium and high contrast stimuli no longer differed significantly. CONCLUSIONS/SIGNIFICANCE: Orientation tuning does not appear to be contrast

  18. Tuning the Engine Skoda 781 for Sport Competitions

    Directory of Open Access Journals (Sweden)

    Ragan Branislav

    2014-12-01

    Full Text Available This article deals with the tuning of a mass-produced engine Skoda 781.136B and its rebuilding into a racing engine. The introduction briefly describes the basic parameters of the massproduced engine. The information is then followed by a detailed description of adjustments to the pipe system, valve timing, cylinder head and crank mechanism. The article presents the benefits in terms of increasing power parameters and there is also a comparison of speed characteristics. The aim of the tuning was to increase the engine power parameters, in particular the torque in the range of 4 000-6 000 min-1, at which the engine most often operates during competitions. The adjustments and optimization of the engine have increased the power parameters in the required range of revolutions by 38-47%.

  19. Microwave microstrip resonators tuning without quality factor deterioration

    Directory of Open Access Journals (Sweden)

    P. Y. Serhienko

    2014-04-01

    Full Text Available Stub and ring resonators with resonance frequency micromechanical tuning are presented. Benefits and main differences of micromechanical resonance frequency tuning method from other methods are shown. Normalized dependences of effective permittivity on normalized air gap values for various microstrip line electrode width to substrate height ratios are obtained. Effective permittivity analytical formulas for the case of infinitely wide electrodes are derived. Calculated and experimental dependences of resonance frequency on air gap value and stub experimental unloaded quality factor dependences are given. Air gap influence on resonance frequency value depending on substrate permittivity is shown in terms of the resonance frequency sensitivity. Error estimation for measured experimental data is presented. Adding tunable heterogeneity between the microstrip resonator signal electrode and the substrate provides not only the resonance frequency tuning but preserves unloaded quality factor. The preservation of the unloaded quality factor during the resonance frequency tuning achieved due to the metal and dielectric loss reduction. Air gap doesn’t have dissipative losses and has permittivity of one, which makes it the best solution for unloaded quality factor preservation. Another important conclusion is that insertion of the air heterogeneity reduces values of dielectric and metal losses arising when substrates with high permittivity are used. For dielectric loss reduction, it is important to maintain low ratio of microstrip line width to substrate height. In contrast to dielectric losses for metal loss reduction the ratio of microstrip line width to substrate height should be high. However, that ratio is limited by impedance permissible range.

  20. A varactor tuned low-cost 24 GHz harmonic VCO

    Directory of Open Access Journals (Sweden)

    M. O. Olbrich

    2006-01-01

    Full Text Available We present a low-cost 24 GHz VCO that is based on a microstrip design combined with discrete packaged devices. The output frequency is generated by a harmonic oscillator. The tunabilty was reached using a varactor diode. Two versions of the VCO were built, one has a wide tuning range of 1.1 GHz and the other one has a high output power of 3.7 dBm.

  1. ORMOSIL thin films: tuning mechanical properties via a nanochemistry approach.

    Science.gov (United States)

    Palmisano, Giovanni; Le Bourhis, Eric; Ciriminna, Rosaria; Tranchida, Davide; Pagliaro, Mario

    2006-12-19

    The mechanical properties (hardness and elastic modulus) of organically modified silicate thin films can be finely tuned by varying the degree of alkylation and thus the fraction of six- and four-membered siloxane rings in the organosilica matrix. This opens the way to large tunability of parameters that are of crucial practical importance for films that are finding increasing application in numerous fields ranging from microelectronics to chemical sensing.

  2. Tuning a microcavity-coupled terahertz laser

    Energy Technology Data Exchange (ETDEWEB)

    Castellano, Fabrizio; Bianchi, Vezio; Vitiello, Miriam S., E-mail: miriam.vitiello@sns.it [NEST, CNR-Istituto Nanoscienze and Scuola Normale Superiore, Piazza San Silvestro 12, 56127 Pisa (Italy); Li, Lianhe; Zhu, Jingxuan; Linfield, Edmund H.; Giles Davies, A. [School of Electronic and Electrical Engineering, University of Leeds, Leeds LS2 9JT (United Kingdom); Tredicucci, Alessandro [Dipartimento di Fisica, Università degli Studi di Pisa, Largo Pontecorvo 6, 56127 Pisa (Italy)

    2015-12-28

    Tunable oscillators are a key component of almost all electronic and photonic systems. Yet, a technology capable of operating in the terahertz (THz)-frequency range and fully suitable for widescale implementation is still lacking. This issue is significantly limiting potential THz applications in gas sensing, high-resolution spectroscopy, hyper-spectral imaging, and optical communications. The THz quantum cascade laser is arguably the most promising solution in terms of output power and spectral purity. In order to achieve reliable, repeatable, and broad tunability, here we exploit the strong coupling between two different cavity mode concepts: a distributed feedback one-dimensional photonic resonator (providing gain) and a mechanically actuated wavelength-size microcavity (providing tuning). The result is a continuously tunable, single-mode emitter covering a 162 GHz spectral range, centered on 3.2 THz. Our source has a few tens of MHz resolution, extremely high differential efficiency, and unprecedented compact and simple design architecture. By unveiling the large potential that lies in this technique, our results provide a robust platform for radically different THz systems exploiting broadly tunable semiconductor lasers.

  3. Tune measurement at GSI SIS-18. Methods and applications

    Energy Technology Data Exchange (ETDEWEB)

    Singh, Rahul

    2014-05-15

    parameters,thus leaving out no ''free parameters''. Several important results were established in course of these experiments. Coherent tune shifts in dependence of intensity gave direct measurements of transverse machine impedances. The high resolution tune spectrum allowed identification of higher order head-tail modes. The relative spectral positions of these head-tail modes when compared with the analytical theory based on the ''square well airbag model'' gave a direct measurement of the incoherent tune spread in bunched beams. The measurements agreed well with the perturbative treatment applied in the theory only for space charge parameter in the range q{sub sc} tune measurement systems such as linear betatron coupling measurements or tune measurements during acceleration ramps are demonstrated. This work forms a basis for understanding beam dynamics at GSI SIS-18 for high beam currents.

  4. Two-level tuning of fuzzy PID controllers.

    Science.gov (United States)

    Mann, G I; Hu, B G; Gosine, R G

    2001-01-01

    Fuzzy PID tuning requires two stages of tuning; low level tuning followed by high level tuning. At the higher level, a nonlinear tuning is performed to determine the nonlinear characteristics of the fuzzy output. At the lower level, a linear tuning is performed to determine the linear characteristics of the fuzzy output for achieving overall performance of fuzzy control. First, different fuzzy systems are defined and then simplified for two-point control. Non-linearity tuning diagrams are constructed for fuzzy systems in order to perform high level tuning. The linear tuning parameters are deduced from the conventional PID tuning knowledge. Using the tuning diagrams, high level tuning heuristics are developed. Finally, different applications are demonstrated to show the validity of the proposed tuning method.

  5. Precision Corrections to Fine Tuning in SUSY

    CERN Document Server

    Buckley, Matthew R; Shih, David

    2016-01-01

    Requiring that the contributions of supersymmetric particles to the Higgs mass are not highly tuned places upper limits on the masses of superpartners -- in particular the higgsino, stop, and gluino. We revisit the details of the tuning calculation and introduce a number of improvements, including RGE resummation, two-loop effects, a proper treatment of UV vs. IR masses, and threshold corrections. This improved calculation more accurately connects the tuning measure with the physical masses of the superpartners at LHC-accessible energies. After these refinements, the tuning bound on the stop is now also sensitive to the masses of the 1st and 2nd generation squarks, which limits how far these can be decoupled in Effective SUSY scenarios. We find that, for a fixed level of tuning, our bounds can allow for heavier gluinos and stops than previously considered. Despite this, the natural region of supersymmetry is under pressure from the LHC constraints, with high messenger scales particularly disfavored.

  6. Musical experience sharpens human cochlear tuning.

    Science.gov (United States)

    Bidelman, Gavin M; Nelms, Caitlin; Bhagat, Shaum P

    2016-05-01

    The mammalian cochlea functions as a filter bank that performs a spectral, Fourier-like decomposition on the acoustic signal. While tuning can be compromised (e.g., broadened with hearing impairment), whether or not human cochlear frequency resolution can be sharpened through experiential factors (e.g., training or learning) has not yet been established. Previous studies have demonstrated sharper psychophysical tuning curves in trained musicians compared to nonmusicians, implying superior peripheral tuning. However, these findings are based on perceptual masking paradigms, and reflect engagement of the entire auditory system rather than cochlear tuning, per se. Here, by directly mapping physiological tuning curves from stimulus frequency otoacoustic emissions (SFOAEs)-cochlear emitted sounds-we show that estimates of human cochlear tuning in a high-frequency cochlear region (4 kHz) is further sharpened (by a factor of 1.5×) in musicians and improves with the number of years of their auditory training. These findings were corroborated by measurements of psychophysical tuning curves (PTCs) derived via simultaneous masking, which similarly showed sharper tuning in musicians. Comparisons between SFOAE and PTCs revealed closer correspondence between physiological and behavioral curves in musicians, indicating that tuning is also more consistent between different levels of auditory processing in trained ears. Our findings demonstrate an experience-dependent enhancement in the resolving power of the cochlear sensory epithelium and the spectral resolution of human hearing and provide a peripheral account for the auditory perceptual benefits observed in musicians. Both local and feedback (e.g., medial olivocochlear efferent) mechanisms are discussed as potential mechanisms for experience-dependent tuning. Copyright © 2016 Elsevier B.V. All rights reserved.

  7. A reconfigurable OTA-C baseband filter with wide digital tuning for GNSS receivers

    Energy Technology Data Exchange (ETDEWEB)

    Pan Wenguang; Gan Yebing [Institute of Microelectronics, Chinese Academy of Sciences, Beijing 100029 (China); Ma Chengyan; Ye Tianchun, E-mail: panwenguang@casic.ac.c [Hangzhou Zhongke Microelectronics Co. Ltd, Hangzhou 310053 (China)

    2010-09-15

    The design of a digitally-tunable sixth-order reconfigurable OTA-C filter in a 0.18-{mu}m RFCMOS process is proposed. The filter can be configured as a complex band pass filter or two real low pass filters. An improved digital automatic frequency tuning scheme based on the voltage controlled oscillator technique is adopted to compensate for process variations. An extended tuning range (above 8:1) is obtained by using widely continuously tunable transconductors based on digital techniques. In the complex band pass mode, the bandwidth can be tuned from 3 to 24 MHz and the center frequency from 3 to 16 MHz. (semiconductor integrated circuits)

  8. Binaurality and azimuth tun-ing of neurons in the auditorycortex of the big brown bat

    Institute of Scientific and Technical Information of China (English)

    2002-01-01

    By using a combined closed and free-field stimulation system, binaurality and azimuth tuning of the neurons in the auditory cortex of the big brown bat, Eptesicus fuscus, were studied. A variety of azimuth-tuning functions were demonstrated for the binaural neurons. The large majority of EE (contralateral and ipsilateral excitatory) neurons exhibited azimuth selectivity with the best azimuths (BA) at contralateral 30(- 40(, some at ipsilateral 20(-40( and preferred azimuth ranges (PAR, response amplitude ≥75% of maximum) between 8( and 40(. Sound source azimuths strongly modulate spike counts with a mean modulation depth of 83.8% for EE neurons. EI (contralateral excitatory and ipsilateral inhibitory) neurons have simple azimuth tuning with BA located at contralateral 20(-40( and a broad PAR ranged from 30( to 55(. The present results suggest that azimuth-tuning characteristics of binaural neurons in the auditory cortex of the bat are of significance for acoustic behaviour.

  9. Tune variations in the Large Hadron Collider

    Energy Technology Data Exchange (ETDEWEB)

    Aquilina, N. [CERN, Geneva (Switzerland); University of Malta, Msida (Malta); Giovannozzi, M.; Lamont, M. [CERN, Geneva (Switzerland); Sammut, N. [University of Malta, Msida (Malta); Steinhagen, R. [CERN, Geneva (Switzerland); Todesco, E., E-mail: ezio.todesco@cern.ch [CERN, Geneva (Switzerland); Wenninger, J. [CERN, Geneva (Switzerland)

    2015-04-01

    The horizontal and vertical betatron tunes of the Large Hadron Collider (LHC) mainly depend on the strength of the quadrupole magnets, but are also affected by the quadrupole component in the main dipoles. In case of systematic misalignments, the sextupole component from the main dipoles and sextupole corrector magnets also affect the tunes due to the feed down effect. During the first years of operation of the LHC, the tunes have been routinely measured and corrected through either a feedback or a feed forward system. In this paper, the evolution of the tunes during injection, ramp and flat top are reconstructed from the beam measurements and the settings of the tune feedback loop and of the feed forward corrections. This gives the obtained precision of the magnetic model of the machine with respect to quadrupole and sextupole components. Measurements at the injection plateau show an unexpected large decay whose origin is not understood. This data is discussed together with the time constants and the dependence on previous cycles. We present results of dedicated experiments that show that this effect does not originate from the decay of the main dipole component. During the ramp, the tunes drift by about 0.022. It is shown that this is related to the precision of tracking the quadrupole field in the machine and this effect is reduced to about 0.01 tune units during flat top.

  10. Broad electrical tuning of graphene-loaded plasmonic antennas.

    Science.gov (United States)

    Yao, Yu; Kats, Mikhail A; Genevet, Patrice; Yu, Nanfang; Song, Yi; Kong, Jing; Capasso, Federico

    2013-03-13

    Plasmonic antennas enable the conversion of light from free space into subwavelength volumes and vice versa, which facilitates the manipulation of light at the nanoscale. Dynamic control of the properties of antennas is desirable for many applications, including biochemical sensors, reconfigurable meta-surfaces and compact optoelectronic devices. The combination of metallic structures and graphene, which has gate-voltage dependent optical properties, is emerging as a possible platform for electrically controlled plasmonic devices. In this paper, we demonstrate in situ control of antennas using graphene as an electrically tunable load in the nanoscale antenna gap. In our experiments, we demonstrate electrical tuning of graphene-loaded antennas over a broad wavelength range of 650 nm (∼140 cm(-1), ∼10% of the resonance frequency) in the mid-infrared (MIR) region. We propose an equivalent circuit model to quantitatively analyze the tuning behavior of graphene-loaded antenna pairs and derive an analytical expression for the tuning range of resonant wavelength. In a separate experiment, we used doubly resonant antenna arrays to achieve MIR optical intensity modulation with maximum modulation depth of more than 30% and bandwidth of 600 nm (∼100 cm(-1), 8% of the resonance frequency). This study shows that combining graphene with metallic nanostructures provides a route to electrically tunable optical and optoelectronic devices.

  11. Experimental Demostration of Wavelength Tuning in High-Gain Harmonic Generation Free Electron Laser

    CERN Document Server

    Shaftan, Timur; Krinsky, Sam; Loos, Henrik; Murphy, James; Rakowsky, George; Rose, James; Sheehy, Brian; Skaritka, John; Wang, Xijie; Wu, Zilu; Yu Li Hua

    2004-01-01

    We present experimental results on tuning of the HGHG FEL output wavelength while holding the input seed wavelength constant. Using compression of the initially chirped beam in the HGHG dispersion section we have measured the wavelength shift of about 1% around the nominal value of 266 nm. The tuning range is expected to reach 3 % after the dispersive section upgrade at the DUV FEL. An optimized design based on this principle, using additional linac sections, would have the capability of providing full tunability.

  12. Experimental Study on Friction in Ferrules during Compression Tuning of Fiber Bragg Grating

    Institute of Scientific and Technical Information of China (English)

    Ling Zhao; Jianxin Geng; Lin Li; Zujie Fang

    2003-01-01

    The effect of friction in ferules on compression tuning characteristics of fiber Bragg gratings (FBG) was observed and analyzed in this paper. It was demonstrated that the friction would make a non-uniform strain in the FBG and degradations of its reflection spectrum. To avoid the effect, some measures have been applied. Near 9 nm tuning range can be obtained with good spectral performance.

  13. Electrical tuning of an optical antenna (Conference Presentation)

    Science.gov (United States)

    Brongersma, Mark L.

    2016-09-01

    The scaling of active photonic devices to deep-submicron length-scales has been hampered by the fundamental law of diffraction and the absence of materials with sufficiently strong electrooptic effects. Here, we demonstrate a solid state electro-optical switching mechanism that can operate in the visible spectral range with an active volume that is comparable to the size of the smallest active electronic components. The switching mechanism relies on electrochemically displacing atoms inside the nanometer-scale gap between two crossed metallic wires forming a crosspoint junction. Such junctions afford extreme light concentration and display singular optical behavior upon formation of a conductive channel. We illustrate how this effect can be used to actively tune the resonances of a plasmonic antenna. The tuning mechanism is analyzed using a combination of electrical and optical measurements as well as electron energy loss (EELS) in a scanning transmission electron microscope (STEM).

  14. High-speed spectral tuning CARS microscopy using AOTF laser

    Science.gov (United States)

    Hashimoto, Mamoru; Iwatsuka, Junichi; Niioka, Hirohiko; Araki, Tsutomu

    2012-03-01

    We have developed a high speed spectral tuning CARS microscopy system using a mode-locked Ti:Sapphire laser with an acousto-optic tunable filter (AOTF) in the cavity. Since the wavelength of the laser is tunable with the applied radio frequency to the AOTF, the wavelength is electrically tunable.The pulse duration of the laser is about 10 ps, tunable range is 800 nm to 930 nm, and the tuning speed is ms order. The laser is synchronized with another mode-locked Ti:Sapphire laser laser our own method using a balance cross-correlator and phase lock loop technique. The synchronized lasers are used for light source of multi-focus CARS microscopy system using a microlens array scanner, and the hyperspectral imaging of adipocyte cells is demonstrated.

  15. Stop on Top: SUSY Parameter Regions, Fine-Tuning Constraints

    CERN Document Server

    Demir, Durmus Ali

    2014-01-01

    We analyze common supersymmetric models in order to determine in what parameter regions with what amount of fine-tuning they are capable of accomodating the LHC-allowed top-stop degeneracy window. The stops must be light enough to enable Higgs naturalness yet heavy enough to induce a 125 GeV Higgs boson mass. These two constraints require the two stops to have a large mass splitting. We find that, compared to the usual neutralino-LSP CMSSM, the NUHM and gravitino-LSP CMSSM models possess relatively wide regions in which the light stop weighs close to the top quark. The fine-tuning involved lies in 10^3-10^4 range.

  16. A STUDY OF RAPID CAVITY TUNING.

    Energy Technology Data Exchange (ETDEWEB)

    ZHAO, Y.

    2001-07-12

    An FFAG moot likely requires rapid cavity tuning. The cavity must also have a very high gradient. To satisfy both the high power and rapid tuning requirements is a big challenge. Detailed investigation of the possibility is addressed. Included are general thoughts, dual-loop and simple loop analyses, and a study of using ferrite or PIN diodes. Also proposed is a phase control scheme, which may be a better solution if the needed components can be developed. Finally, an energy analysis reveals the difficult of high power tuning.

  17. Frequency Tuning for a DQW Crab Cavity

    CERN Document Server

    Verdú-Andrés, Silvia; Ben-Zvi, Ilan; Calaga, Rama; Capatina, Ofelia; Leuxe, Raphael; Skaritka, John; Wu, Qiong; Xiao, Binping; Zanoni, Carlo

    2016-01-01

    The nominal operating frequency for the HL-LHC crab cavities is 400.79 MHz within a bandwidth of ±60kHz. Attaining the required cavity tune implies a good understanding of all the processes that influence the cavity frequency from the moment when the cavity parts are being fabricated until the cavity is installed and under operation. Different tuning options will be available for the DQW crab cavity of LHC. This paper details the different steps in the cavity fabrication and preparation that may introduce a shift in the cavity frequency and introduces the different tuning methods foreseen to bring the cavity frequency to meet the specifications.

  18. Entropy-based Tuning of Musical Instruments

    CERN Document Server

    Hinrichsen, Haye

    2012-01-01

    The human sense of hearing perceives a combination of sounds 'in tune' if the corresponding harmonic spectra are correlated, meaning that the neuronal excitation pattern in the inner ear exhibits some kind of order. Based on this observation it is suggested that musical instruments such as pianos can be tuned by minimizing the Shannon entropy of suitably preprocessed Fourier spectra. This method reproduces not only the correct stretch curve but also similar pitch fluctuations as in the case of high-quality aural tuning.

  19. ARTUS: The tune measurement system at RHIC

    Science.gov (United States)

    Drees, A.; Brennan, M.; Connolly, R.; Michnoff, R.; DeLong, J.

    2000-11-01

    The super-conducting Relativistic Heavy Ion Collider (RHIC) with two separate rings and six combined interaction regions will provide collisions between equal and unequal heavy ion species up to Au ions in typically 60 bunches. The betatron tunes of the two beams are among the most important parameters to be measured. The tunes have to be acquired at any moment during accelerator operation and in particular during the acceleration process. At RHIC the tune measurement device (ARTUS) consists of a fast horizontal and vertical kicker magnet and a dedicated beam position monitor in each ring. The system layout is described and first experiences from operation is reported.

  20. The ratio of the kinetic inductance to the geometric inductance: a key parameter for the frequency tuning of the THz semiconductor split-ring resonator.

    Science.gov (United States)

    Cong, Jiawei; Yun, Binfeng; Cui, Yiping

    2013-08-26

    By introducing the frequency tuning sensitivity, an analytical model based on equivalent LC circuit is developed for the relative frequency tuning range of THz semiconductor split-ring resonator (SRR). And the model reveals that the relative tuning range is determined by the ratio of the kinetic inductance to the geometric inductance (RKG). The results show that under the same carrier density variation, a larger RKG results in a larger relative tuning range. Based on this model, a stacked SRR-dimer structure with larger RKG compared to the single SRR due to the inductive coupling is proposed, which improves the relative tuning range effectively. And the results obtained by the simple analytical model agree well with the numerical FDTD results. The presented analytical model is robust and can be used to analyze the relative frequency tuning of other tunable THz devices.

  1. Study on the Tuning of PEFP DTL

    Energy Technology Data Exchange (ETDEWEB)

    Kim, Han Sung; Kwon, Hyeok Jung; Seol, Kyung Tae; Cho, Yong Sub [Korea Atomic Energy Research Institute, Daejeon (Korea, Republic of); Hwang, Yong Suk [Seoul National Univ., Seoul (Korea, Republic of)

    2005-07-01

    A conventional 20 MeV drift tube linac(DTL) for the Proton Engineering Frontier Project(PEFP) has been developed as a low energy section of 100 MeV accelerator. The DTL consists of four tanks with 152 cells supplied with 900 kW RF power from 350 MHz klystron through the ridge-loaded waveguide coupler. After the fabrication and assembling of the DTL, it should be tuned to meet the requirement of the resonant frequency and field profile. The tuning goal of the resonant frequency is 350 MHz at 40 .deg. C and that of the field flatness is {+-}1%. We performed the bead pull measurements under various combinations of slug tuners position and post couplers position. The final tuning can be obtained through several iterations of the tuner position adjustment and measurement. The methods and the results of the DTL tuning will be given in this presentation.

  2. Accurate guitar tuning by cochlear implant musicians.

    Directory of Open Access Journals (Sweden)

    Thomas Lu

    Full Text Available Modern cochlear implant (CI users understand speech but find difficulty in music appreciation due to poor pitch perception. Still, some deaf musicians continue to perform with their CI. Here we show unexpected results that CI musicians can reliably tune a guitar by CI alone and, under controlled conditions, match simultaneously presented tones to <0.5 Hz. One subject had normal contralateral hearing and produced more accurate tuning with CI than his normal ear. To understand these counterintuitive findings, we presented tones sequentially and found that tuning error was larger at ∼ 30 Hz for both subjects. A third subject, a non-musician CI user with normal contralateral hearing, showed similar trends in performance between CI and normal hearing ears but with less precision. This difference, along with electric analysis, showed that accurate tuning was achieved by listening to beats rather than discriminating pitch, effectively turning a spectral task into a temporal discrimination task.

  3. Event generator tuning using Bayesian optimization

    CERN Document Server

    Ilten, Philip; Yang, Yunjie

    2016-01-01

    Monte Carlo event generators contain a large number of parameters that must be determined by comparing the output of the generator with experimental data. Generating enough events with a fixed set of parameter values to enable making such a comparison is extremely CPU intensive, which prohibits performing a simple brute-force grid-based tuning of the parameters. Bayesian optimization is a powerful method designed for such black-box tuning applications. In this article, we show that Monte Carlo event generator parameters can be accurately obtained using Bayesian optimization and minimal expert-level physics knowledge. A tune of the PYTHIA 8 event generator using $e^+e^-$ events, where 20 parameters are optimized, can be run on a modern laptop in just two days. Combining the Bayesian optimization approach with expert knowledge should enable producing better tunes in the future, by making it faster and easier to study discrepancies between Monte Carlo and experimental data.

  4. Dynamic Performance Tuning Supported by Program Specification

    Directory of Open Access Journals (Sweden)

    Eduardo César

    2002-01-01

    Full Text Available Performance analysis and tuning of parallel/distributed applications are very difficult tasks for non-expert programmers. It is necessary to provide tools that automatically carry out these tasks. These can be static tools that carry out the analysis on a post-mortem phase or can tune the application on the fly. Both kind of tools have their target applications. Static automatic analysis tools are suitable for stable application while dynamic tuning tools are more appropriate to applications with dynamic behaviour. In this paper, we describe KappaPi as an example of a static automatic performance analysis tool, and also a general environment based on parallel patterns for developing and dynamically tuning parallel/distributed applications.

  5. Tuning Leaky Nanocavity Resonances - Perturbation Treatment

    CERN Document Server

    Shlafman, Michael; Salzman, Joseph

    2010-01-01

    Adiabatic frequency tuning of finite-lifetime-nanocavity electromagnetic modes affects also their quality-factor (Q). Perturbative Q change resulting from (real) frequency tuning, is a controllable parameter. Here, the influence of dielectric constant modulation (DCM) on cavity resonances is presented, by first order perturbation analysis for a 3D cavity with radiation losses. Semi-analytical expressions for DCM induced cavity mode frequency and Q changes are derived. The obtained results are in good agreement with numerical calculations.

  6. Varactor-tuned Substrate Integrated Evanescent Filter

    DEFF Research Database (Denmark)

    Zhurbenko, Vitaliy; Acar, Öncel; Dong, Yunfeng

    is considered. In contrast to other methods described in the literature, it avoids etching split ring resonators in the metal layer of the SIW. The filters presented here use varactors as tuning elements. The varactors (as well as DC decoupling circuits) are mounted on the surface of PCB bringing the lower......, fabricated and tested in order to validate the developed filter models as well as the implemented realization method. The filter structure as well as its tuning are shown in Figure 1....

  7. Gravity orientation tuning in macaque anterior thalamus.

    Science.gov (United States)

    Laurens, Jean; Kim, Byounghoon; Dickman, J David; Angelaki, Dora E

    2016-12-01

    Gravity may provide a ubiquitous allocentric reference to the brain's spatial orientation circuits. Here we describe neurons in the macaque anterior thalamus tuned to pitch and roll orientation relative to gravity, independently of visual landmarks. We show that individual cells exhibit two-dimensional tuning curves, with peak firing rates at a preferred vertical orientation. These results identify a thalamic pathway for gravity cues to influence perception, action and spatial cognition.

  8. Tuning Metamaterials by using Amorphous Magnetic Microwires

    OpenAIRE

    Lopez-Dominguez, V.; Garcia, M.A.; Marin, P.; Hernando, A.

    2017-01-01

    In this work, we demonstrate theoretically and experimentally the possibility of tuning the electromagnetic properties of metamaterials with magnetic fields by incorporating amorphous magnetic microwires. The large permeability of these wires at microwave frequencies allows tuning the resonance of the metamaterial by using magnetic fields of the order of tens of Oe. We describe here the physical basis of the interaction between a prototypical magnetic metamaterial with magnetic microwires and...

  9. Accurate guitar tuning by cochlear implant musicians.

    Science.gov (United States)

    Lu, Thomas; Huang, Juan; Zeng, Fan-Gang

    2014-01-01

    Modern cochlear implant (CI) users understand speech but find difficulty in music appreciation due to poor pitch perception. Still, some deaf musicians continue to perform with their CI. Here we show unexpected results that CI musicians can reliably tune a guitar by CI alone and, under controlled conditions, match simultaneously presented tones to electric analysis, showed that accurate tuning was achieved by listening to beats rather than discriminating pitch, effectively turning a spectral task into a temporal discrimination task.

  10. Dynamics of the tuning process between singers

    CERN Document Server

    Urteaga, R

    2004-01-01

    We present a dynamical model describing a predictable human behavior like the tuning process between singers. The purpose, inspired in physiological and behavioral grounds of human beings, is sensitive to all Fourier spectrum of each sound emitted and it contemplates an asymmetric coupling between individuals. We have recorded several tuning exercises and we have confronted the experimental evidence with the results of the model finding a very well agreement between calculated and experimental sonograms.

  11. Anisotropy tuning with the Wilson flow

    CERN Document Server

    Borsanyi, S; Fodor, Z; Katz, S D; Krieg, S; Kurth, T; Mages, S; Schafer, A; Szabo, K K

    2012-01-01

    We use the Wilson flow to define the gauge anisotropy at a given physical scale. We demonstrate the use of the anisotropic flow by performing the tuning of the bare gauge anisotropy in the tree-level Symanzik action for several lattice spacings and target anisotropies. We use this method to tune the anisotropy parameters in full QCD, where we also exploit the diminishing effect of a well chosen smearing on the renormalization of the fermion anisotropy.

  12. Range Tracing

    OpenAIRE

    Jenke, Philipp; Huhle, Benjamin

    2010-01-01

    In this report, we tackle the problem of merging an arbitrary number of range scans (depth images) into a single surface mesh. The mesh-based representation is superior to point-based approaches since it contains important connectivity information. Most previous mesh-based merge methods, however, lose surface details by using simplifying intermediate surface representations (e.g.\\ implicit functions). Such details are essential for further processing steps, especially for feature-preserving r...

  13. Revisiting fine-tuning in the MSSM

    Science.gov (United States)

    Ross, Graham G.; Schmidt-Hoberg, Kai; Staub, Florian

    2017-03-01

    We evaluate the amount of fine-tuning in constrained versions of the minimal supersymmetric standard model (MSSM), with different boundary conditions at the GUT scale. Specifically we study the fully constrained version as well as the cases of non-universal Higgs and gaugino masses. We allow for the presence of additional non-holomorphic soft-terms which we show further relax the fine-tuning. Of particular importance is the possibility of a Higgsino mass term and we discuss possible origins for such a term in UV complete models. We point out that loop corrections typically lead to a reduction in the fine-tuning by a factor of about two compared to the estimate at tree-level, which has been overlooked in many recent works. Taking these loop corrections into account, we discuss the impact of current limits from SUSY searches and dark matter on the fine-tuning. Contrary to common lore, we find that the MSSM fine-tuning can be as small as 10 while remaining consistent with all experimental constraints. If, in addition, the dark matter abundance is fully explained by the neutralino LSP, the fine-tuning can still be as low as ˜ 20 in the presence of additional non-holomorphic soft-terms. We also discuss future prospects of these models and find that the MSSM will remain natural even in the case of a non-discovery in the foreseeable future.

  14. An optimal tuning strategy for tidal turbines

    Science.gov (United States)

    Vennell, Ross

    2016-11-01

    Tuning wind and tidal turbines is critical to maximizing their power output. Adopting a wind turbine tuning strategy of maximizing the output at any given time is shown to be an extremely poor strategy for large arrays of tidal turbines in channels. This `impatient-tuning strategy' results in far lower power output, much higher structural loads and greater environmental impacts due to flow reduction than an existing `patient-tuning strategy' which maximizes the power output averaged over the tidal cycle. This paper presents a `smart patient tuning strategy', which can increase array output by up to 35% over the existing strategy. This smart strategy forgoes some power generation early in the half tidal cycle in order to allow stronger flows to develop later in the cycle. It extracts enough power from these stronger flows to produce more power from the cycle as a whole than the existing strategy. Surprisingly, the smart strategy can often extract more power without increasing maximum structural loads on the turbines, while also maintaining stronger flows along the channel. This paper also shows that, counterintuitively, for some tuning strategies imposing a cap on turbine power output to limit loads can increase a turbine's average power output.

  15. An optimal tuning strategy for tidal turbines.

    Science.gov (United States)

    Vennell, Ross

    2016-11-01

    Tuning wind and tidal turbines is critical to maximizing their power output. Adopting a wind turbine tuning strategy of maximizing the output at any given time is shown to be an extremely poor strategy for large arrays of tidal turbines in channels. This 'impatient-tuning strategy' results in far lower power output, much higher structural loads and greater environmental impacts due to flow reduction than an existing 'patient-tuning strategy' which maximizes the power output averaged over the tidal cycle. This paper presents a 'smart patient tuning strategy', which can increase array output by up to 35% over the existing strategy. This smart strategy forgoes some power generation early in the half tidal cycle in order to allow stronger flows to develop later in the cycle. It extracts enough power from these stronger flows to produce more power from the cycle as a whole than the existing strategy. Surprisingly, the smart strategy can often extract more power without increasing maximum structural loads on the turbines, while also maintaining stronger flows along the channel. This paper also shows that, counterintuitively, for some tuning strategies imposing a cap on turbine power output to limit loads can increase a turbine's average power output.

  16. Thermo-Optical Tuning of Whispering Gallery Modes in Er:Yb Doped Glass Microspheres to Arbitrary Probe Wavelengths

    CERN Document Server

    Watkins, Amy; Chormaic, Síle Nic

    2012-01-01

    We present experimental results on an all-optical, thermally-assisted technique for broad range tuning of microsphere cavity resonance modes to arbitrary probe wavelengths. An Er:Yb co-doped phosphate glass (Schott IOG-2) microsphere is pumped at 978 nm via the supporting stem and the heat generated by absorption of the pump light expands the cavity and changes the refractive index. This is a robust tuning method that decouples the pump from the probe and allows fine tuning of the microsphere's whispering gallery modes. Pump/probe experiments were performed to demonstrate thermo-optical tuning to specific probe wavelengths, including the 5S1/2 F = 3 to 5P3/2 F' = 4 laser cooling transition of 85Rb. This is of particular interest for cavity QED-type experiments, while the broad tuning range achievable is useful for integrated photonic devices, including sensors and modulators.

  17. Thermo-Optical Tuning of Whispering Gallery Modes in Erbium:Ytterbium Doped Glass Microspheres to Arbitrary Probe Wavelengths

    Science.gov (United States)

    Watkins, Amy; Ward, Jonathan; Chormaic, Síle Nic

    2012-05-01

    We present experimental results on an all-optical, thermally-assisted technique for broad range tuning of microsphere cavity resonance modes to arbitrary probe wavelengths. An erbium:ytterbium co-doped phosphate glass (Schott IOG-2) microsphere is pumped at 978 nm via the supporting stem and the heat generated by absorption of the pump light expands the cavity and changes the refractive index. This is a robust tuning method that decouples the pump from the probe and allows fine tuning of the microsphere's whispering gallery modes. Pump/probe experiments were performed to demonstrate thermo-optical tuning to specific probe wavelengths, including the 5S1/2 F= 3 to 5P3/2 F'= 4 laser cooling transition of rubidium-85. This is of particular interest for cavity quantum electrodynamics (QED)-type experiments, while the broad tuning range achievable is useful for integrated photonic devices, including sensors and modulators.

  18. Haggling over the fine-tuning price of LEP

    CERN Document Server

    Chankowski, P H; Olechowski, M; Pokorski, Stefan

    1999-01-01

    We amplify previous discussions of the fine-tuning price to be paid by supersymmetric models in the light of LEP data, especially the lower bound on the Higgs boson mass, studying in particular its power of discrimination between different parameter regions and different theoretical assumptions. The analysis is performed using the full one-loop effective potential. The whole range of $\\tan\\beta$ is discussed, including large values. In the minimal supergravity model with universal gaugino and scalar masses, a small fine-tuning price is possible only for intermediate values of $\\tan\\beta$. However, the fine-tuning price in this region is significantly higher if we require $b-\\tau$ Yukawa-coupling unification. On the other hand, price reductions are obtained if some theoretical relation between MSSM parameters is assumed, in particular between $\\mu_0$, $M_{1/2}$ and $A_0$. Significant price reductions are obtained for large $\\tan\\beta$ if non-universal soft Higgs mass parameters are allowed. Nevertheless, in al...

  19. An improved auto-tuning scheme for PID controllers.

    Science.gov (United States)

    Dey, Chanchal; Mudi, Rajani K

    2009-10-01

    An improved auto-tuning scheme is proposed for Ziegler-Nichols (ZN) tuned PID controllers (ZNPIDs), which usually provide excessively large overshoots, not tolerable in most of the situations, for high-order and nonlinear processes. To overcome this limitation ZNPIDs are upgraded by some easily interpretable heuristic rules through an online gain modifying factor defined on the instantaneous process states. This study is an extension of our earlier work [Mudi RK., Dey C. Lee TT. An improved auto-tuning scheme for PI controllers. ISA Trans 2008; 47: 45-52] to ZNPIDs, thereby making the scheme suitable for a wide range of processes and more generalized too. The proposed augmented ZNPID (AZNPID) is tested on various high-order linear and nonlinear dead-time processes with improved performance over ZNPID, refined ZNPID (RZNPID), and other schemes reported in the literature. Stability issues are addressed for linear processes. Robust performance of AZNPID is observed while changing its tunable parameters as well as the process dead-time. The proposed scheme is also implemented on a real time servo-based position control system.

  20. Light Stops and Fine-Tuning in MSSM

    CERN Document Server

    Cici, Ali; Un, Cem Salih

    2016-01-01

    We discuss the fine-tuning issue within the MSSM framework. Following the idea that the fine-tuning can measure effects of some missing mechanisms we impose non-universal gaugino masses at the GUT scale, and explore the low scale implications. We consider the stop mass with a special importance and consider the mass scales which are excluded by the LHC experiments. We find that the stop mass can be as light as 200 GeV, while the mass scales below this scale are excluded by the experimental constraints imposed in our analyses. After discussing the fine-tuning and its implications, we consider detection of stop quarks at LHC over some benchmark points which yield stop masses in a range 200-700 GeV. Even though the LHC constraints are severe and they exclude this mass scales for the stop quark, we show that the stops can still escape from detection, when the model is restricted from the GUT scale.

  1. Theoretical model and optimization of a novel temperature sensor based on quartz tuning fork resonators

    Science.gov (United States)

    Jun, Xu; Bo, You; Xin, Li; Juan, Cui

    2007-12-01

    To accurately measure temperatures, a novel temperature sensor based on a quartz tuning fork resonator has been designed. The principle of the quartz tuning fork temperature sensor is that the resonant frequency of the quartz resonator changes with the variation in temperature. This type of tuning fork resonator has been designed with a new doubly rotated cut work at flexural vibration mode as temperature sensor. The characteristics of the temperature sensor were evaluated and the results sufficiently met the target of development for temperature sensor. The theoretical model for temperature sensing has been developed and built. The sensor structure was analysed by finite element method (FEM) and optimized, including tuning fork geometry, tine electrode pattern and the sensor's elements size. The performance curve of output versus measured temperature is given. The results from theoretical analysis and experiments indicate that the sensor's sensitivity can reach 60 ppm °C-1 with the measured temperature range varying from 0 to 100 °C.

  2. High Power Tm3+-Doped Fiber Lasers Tuned by a Variable Reflective Output Coupler

    Directory of Open Access Journals (Sweden)

    Yulong Tang

    2008-01-01

    Full Text Available Wide wavelength tuning by a variable reflective output coupler is demonstrated in high-power double-clad Tm3+-doped silica fiber lasers diode-pumped at ∼790  nm. Varying the output coupling from 96% to 5%, the laser wavelength is tuned over a range of 106  nm from 1949 to 2055  nm. The output power exceeds 20  W over 90-nm range and the maximum output power is 32  W at 1949  nm for 51-W launched pump power, corresponding to a slope efficiency of ∼70%. Assisted with different fiber lengths, the tuning range is expanded to 240  nm from 1866 to 2107  nm with the output power larger than 10  W.

  3. [Laser Tuning Performance Testing and Optimization in TDLAS Oxygen Measuring Systems].

    Science.gov (United States)

    He, Jun-feng; Hu, Jun; Kan, Rui-feng; Xu, Zhen-yu; Wang, Tao

    2015-03-01

    TDLAS (tunable diode laser absorption spectroscopy) technology, with its unmatched advantages such as high selectivity molecular spectra, fast response, high sensitivity, non-contact measuring, become the preferred scheme for combustion process diagnosis, and can be effectively used for oxygen measuring. DFB (distributed feedback) laser diode with its small size, low power consumption, long service life, narrow linewidth, tunable wavelength has become the main choice of the TDLAS system. Performance of laser tuning characteristics is a key factor restricting TDLAS's measuring performance. According to TDLAS oxygen measuring system's working requirements, a simple experimental method was used to test and analyze tuning characteristics such as wavelength current, power current and wavelength temperature of a 764 nm DFB laser diode in the system. Nonlinear distortion of tuning curves was obvious, which affects oxygen measuring accuracy. The laser spectra's characteristics such as narrow linewidth, high side mode suppression ratio and wide wavelength tuning range are obvious, while its wavelength-current tuning curve with a tuning rate of about 0.023 nm x mA(-1) is not strictly linear. The higher the temperature the greater the threshold current, the PI curve is not strictly linear either. Temperature tuning curve is of good linearity, temperature-wave-length tuning rate keeps constant of about 0.056 nm/DEG C. Temperature tuning nonlinearity can be improved by high temperature control accuracy, and current power nonlinearity can be improved by setting the reference light path. In order to solve the wavelength current tuning nonlinear problems, the method of DA controlling injection current was considered to compensate for non-linear wavelength current tuning according to DFB laser diode tuning mechanism and polynomial fitting of test results. In view of different type of lasers, this method needs only one polynomial fitting process before the system's initial work. The

  4. Electric field engineering using quantum-size-effect-tuned heterojunctions

    KAUST Repository

    Adinolfi, V.

    2013-07-03

    A quantum junction solar cell architecture was recently reported that employs colloidal quantum dots (CQDs) on each side of the p-n junction. This architecture extends the range of design opportunities for CQD photovoltaics, since the bandgap can be tuned across the light-absorbing semiconductor layer via control over CQD size, employing solution-processed, room-temperature fabricated materials. We exploit this feature by designing and demonstrating a field-enhanced heterojunction architecture. We optimize the electric field profile within the solar cell through bandgap engineering, thereby improving carrier collection and achieving an increased open circuit voltage, resulting in a 12% improvement in power conversion efficiency.

  5. Electric field engineering using quantum-size-effect-tuned heterojunctions

    Science.gov (United States)

    Adinolfi, V.; Ning, Z.; Xu, J.; Masala, S.; Zhitomirsky, D.; Thon, S. M.; Sargent, E. H.

    2013-07-01

    A quantum junction solar cell architecture was recently reported that employs colloidal quantum dots (CQDs) on each side of the p-n junction. This architecture extends the range of design opportunities for CQD photovoltaics, since the bandgap can be tuned across the light-absorbing semiconductor layer via control over CQD size, employing solution-processed, room-temperature fabricated materials. We exploit this feature by designing and demonstrating a field-enhanced heterojunction architecture. We optimize the electric field profile within the solar cell through bandgap engineering, thereby improving carrier collection and achieving an increased open circuit voltage, resulting in a 12% improvement in power conversion efficiency.

  6. Psychophysical tuning curves for very low centre frequencies

    DEFF Research Database (Denmark)

    Orellana, Carlos Andrés Jurado; Moore, Brian C.J.; Pedersen, Christian Sejer

    2010-01-01

    low frequencies, psychophysical tuning curves (PTCs) were obtained for centre frequencies of 31.5, 40, and 50 Hz. An equal-loudness-level contour was also obtained using closely spaced frequencies. This was used as a rough estimate of the shape of the individual middle-ear transfer function...... in the frequency range below 100 Hz. Preliminary results on 1 subject are described. The PTCs showed distinct irregularities around the signal frequency, which may reflect the influence of beats. However, the overall shapes of the PTCs were broad, indicating that frequency selectivity at low frequencies...

  7. Energy-efficient high performance computing measurement and tuning

    CERN Document Server

    III, James H Laros; Kelly, Sue

    2012-01-01

    In this work, the unique power measurement capabilities of the Cray XT architecture were exploited to gain an understanding of power and energy use, and the effects of tuning both CPU and network bandwidth. Modifications were made to deterministically halt cores when idle. Additionally, capabilities were added to alter operating P-state. At the application level, an understanding of the power requirements of a range of important DOE/NNSA production scientific computing applications running at large scale is gained by simultaneously collecting current and voltage measurements on the hosting nod

  8. Tuning sum rules with window functions for optical constant evaluation

    Science.gov (United States)

    Rodríguez-de Marcos, Luis V.; Méndez, José A.; Larruquert, Juan I.

    2016-07-01

    Sum rules are a useful tool to evaluate the global consistency of a set of optical constants. We present a procedure to spectrally tune sum rules to evaluate the local consistency of optical constants. It enables enhancing the weight of a desired spectral range within the sum-rule integral. The procedure consists in multiplying the complex refractive index with an adapted function, which is named window function. Window functions are constructed through integration of Lorentz oscillators. The asymptotic decay of these window functions enables the derivation of a multiplicity of sum rules akin to the inertial sum rule, along with one modified version of f-sum rule. This multiplicity of sum rules combined with the free selection of the photon energy range provides a double way to tune the spectral contribution within the sum rule. Window functions were applied to reported data of SrF2 and of Al films in order to check data consistency over the spectrum. The use of window functions shows that the optical constants of SrF2 are consistent in a broad spectrum. Regarding Al, some spectral ranges are seen to present a lower consistency, even though the standard sum rules with no window function did not detect inconsistencies. Hence window functions are expected to be a helpful tool to evaluate the local consistency of optical constants.

  9. Discrete PID Tuning Using Artificial Intelligence Techniques

    Directory of Open Access Journals (Sweden)

    Petr DOLEŽEL

    2009-06-01

    Full Text Available PID controllers are widely used in industry these days due to their useful properties such as simple tuning or robustness. While they are applicable to many control problems, they can perform poorly in some applications. Highly nonlinear system control with constrained manipulated variable can be mentioned as an example. The point of the paper is to string together convenient qualities of conventional PID control and progressive techniques based on Artificial Intelligence. Proposed control method should deal with even highly nonlinear systems. To be more specific, there is described new method of discrete PID controller tuning in this paper. This method tunes discrete PID controller parameters online through the use of genetic algorithm and neural model of controlled system in order to control successfully even highly nonlinear systems. After method description and some discussion, there is performed control simulation and comparison to one chosen conventional control method.

  10. Tuning in caudal fastigial nucleus units during natural and galvanic labyrinth stimulation.

    Science.gov (United States)

    Schlosser, H G; Guldin, W O; Grüsser, O J

    2001-05-25

    Neurons of the caudal fastigial nucleus were investigated by means of single unit recordings. Natural vestibular stimuli were applied as well as galvanic labyrinth polarization. One-third of the neurons showed a convergence of vertical and horizontal canals. More than 80% of the neurons responded to polarization of both the ipsilateral and contralateral canals (binaural responders). Most neurons had a limited response range. Two classes of neurons could be distinguished: up to 1 Hz responders and up to 10 Hz responders. In addition a group of fastigial cells showed a tuning within a small range of frequencies (sharp-tuning responders).

  11. Tuned with a tune: Talker normalization via general auditory processes

    Directory of Open Access Journals (Sweden)

    Erika J C Laing

    2012-06-01

    Full Text Available Voices have unique acoustic signatures, contributing to the acoustic variability listeners must contend with in perceiving speech, and it has long been proposed that listeners normalize speech perception to information extracted from a talker’s speech. Initial attempts to explain talker normalization relied on extraction of articulatory referents, but recent studies of context-dependent auditory perception suggest that general auditory referents such as the long-term average spectrum (LTAS of a talker’s speech similarly affect speech perception. The present study aimed to differentiate the contributions of articulatory/linguistic versus auditory referents for context-driven talker normalization effects and, more specifically, to identify the specific constraints under which such contexts impact speech perception. Synthesized sentences manipulated to sound like different talkers influenced categorization of a subsequent speech target only when differences in the sentences’ LTAS were in the frequency range of the acoustic cues relevant for the target phonemic contrast. This effect was true both for speech targets preceded by spoken sentence contexts and for targets preceded by nonspeech tone sequences that were LTAS-matched to the spoken sentence contexts. Specific LTAS characteristics, rather than perceived talker, predicted the results suggesting that general auditory mechanisms play an important role in effects considered to be instances of perceptual talker normalization.

  12. BDS tuning and luminosity monitoring in CLIC

    CERN Document Server

    Dalena, Barbara; Latina, Andrea; Marin, Eduardo; Pfingstner, Jurgen; Schulte, Daniel; Snuverink, Jochem; Tomas, Rogelio; Zamudio, Guillermo

    2011-01-01

    The emittance preservation in the Beam Delivery System (BDS) is one of the major challenges in CLIC. The fast detuning of the final focus optics requires an on-­line tuning procedure in order to keep luminosity close to the maximum. Different tuning techniques have been applied to the CLIC BDS and in particular to the Final Focus System (FFS) in order to mitigate static and dynamic imperfections. Some of them require a fast luminosity measurement. Here we study the possibility to use beam-­beam backgrounds processes at CLIC 3 TeV CM energy as fast luminosity signal. In particular the hadrons multiplicity in the detector region is investigated.

  13. Tuning Metamaterials by using Amorphous Magnetic Microwires.

    Science.gov (United States)

    Lopez-Dominguez, V; Garcia, M A; Marin, P; Hernando, A

    2017-08-24

    In this work, we demonstrate theoretically and experimentally the possibility of tuning the electromagnetic properties of metamaterials with magnetic fields by incorporating amorphous magnetic microwires. The large permeability of these wires at microwave frequencies allows tuning the resonance of the metamaterial by using magnetic fields of the order of tens of Oe. We describe here the physical basis of the interaction between a prototypical magnetic metamaterial with magnetic microwires and electromagnetic waves plus providing detailed calculations and experimental results for the case of an array of Split Ring Resonators with Co-based microwires.

  14. The nonlinear piezoelectric tuned vibration absorber

    Science.gov (United States)

    Soltani, P.; Kerschen, G.

    2015-07-01

    This paper proposes a piezoelectric vibration absorber, termed the nonlinear piezoelectric tuned vibration absorber (NPTVA), for the mitigation of nonlinear resonances of mechanical systems. The new feature of the NPTVA is that its nonlinear restoring force is designed according to a principle of similarity, i.e., the NPTVA should be an electrical analog of the nonlinear host system. Analytical formulas for the NPTVA parameters are derived using the homotopy perturbation method. Doing so, a nonlinear generalization of Den Hartog’s equal-peak tuning rule is developed for piezoelectric vibration absorbers.

  15. Java EE 7 performance tuning and optimization

    CERN Document Server

    Oransa, Osama

    2014-01-01

    The book adopts a step-by-step approach, starting from building the basics and adding to it gradually by using different tools and examples. The book sequence is easy to follow and all topics are fully illustrated showing you how to make good use of different performance diagnostic tools. If you are an experienced Java developer, architect, team leader, consultant, support engineer, or anyone else who needs performance tuning in your Java applications, and in particular, Java enterprise applications, this book is for you. No prior experience of performance tuning is required.

  16. A New Tuning Method for Two-Degree-of-Freedom Internal Model Control under Parametric Uncertainty

    Institute of Scientific and Technical Information of China (English)

    Juwari Purwo sutikno; Badhrulhisham Abdul aziz; Chin Sim yee; Rosbi Mamat

    2013-01-01

    Internal model control (IMC) yields very good performance for set point tracking, but gives sluggish response for disturbance rejection problem. A two-degree-of-freedom IMC (2DOF-IMC) has been developed to overcome the weakness. However, the setting of parameter becomes a complicated matter if there is an uncertainty model. The present study proposes a new tuning method for the controller. The proposed tuning method consists of three steps. Firstly, the worst case of the model uncertainty is determined. Secondly, the parameter of set point con-troller using maximum peak (Mp) criteria is specified, and finally, the parameter of the disturbance rejection con-troller using gain margin (GM) criteria is obtained. The proposed method is denoted as Mp-GM tuning method. The effectiveness of Mp-GM tuning method has evaluated and compared with IMC-controller tuning program (IMCTUNE) as bench mark. The evaluation and comparison have been done through the simulation on a number of first order plus dead time (FOPDT) and higher order processes. The FOPDT process tested includes processes with controllability ratio in the range 0.7 to 2.5. The higher processes include second order with underdamped and third order with nonminimum phase processes. Although the two of higher order processes are considered as difficult processes, the proposed Mp-GM tuning method are able to obtain the good controller parameter even under process uncertainties.

  17. Closed-loop step response for tuning PID-fractional-order-filter controllers.

    Science.gov (United States)

    Amoura, Karima; Mansouri, Rachid; Bettayeb, Maâmar; Al-Saggaf, Ubaid M

    2016-09-01

    Analytical methods are usually applied for tuning fractional controllers. The present paper proposes an empirical method for tuning a new type of fractional controller known as PID-Fractional-Order-Filter (FOF-PID). Indeed, the setpoint overshoot method, initially introduced by Shamsuzzoha and Skogestad, has been adapted for tuning FOF-PID controller. Based on simulations for a range of first order with time delay processes, correlations have been derived to obtain PID-FOF controller parameters similar to those obtained by the Internal Model Control (IMC) tuning rule. The setpoint overshoot method requires only one closed-loop step response experiment using a proportional controller (P-controller). To highlight the potential of this method, simulation results have been compared with those obtained with the IMC method as well as other pertinent techniques. Various case studies have also been considered. The comparison has revealed that the proposed tuning method performs as good as the IMC. Moreover, it might offer a number of advantages over the IMC tuning rule. For instance, the parameters of the fractional controller are directly obtained from the setpoint closed-loop response data without the need of any model of the plant to be controlled.

  18. Large tuning of narrow-beam terahertz plasmonic lasers operating at 78 K

    CERN Document Server

    Wu, Chongzhao; Reno, John L; Kumar, Sushil

    2016-01-01

    A new tuning mechanism is demonstrated for single-mode metal-clad plasmonic lasers, in which refractive-index of the laser's surrounding medium affects the resonant-cavity mode in the same vein as refractive-index of gain medium inside the cavity. Reversible, continuous, and mode-hop-free tuning of 57 GHz is realized for single-mode narrow-beam terahertz plasmonic quantum-cascade lasers (QCLs), which emit at ~2.8 THz and operate in a liquid-nitrogen cooled dewar. The tuning is based on post-process deposition/etching of a dielectric (Silicon-dioxide) on a QCL chip that has already been soldered and wire-bonded onto a copper mount. This is a considerably larger tuning range compared to previously reported results for single-mode terahertz QCLs with directional far-field radiation patterns. Also, the tuning is demonstrated at the much more practical operating temperature of 78 K, whereas all previous tuning results for terahertz QCLs have been reported at low-temperatures (4-20 K). The key enabling mechanism fo...

  19. Labile cochlear tuning in the mustached bat. II. Concomitant shifts in neural tuning.

    Science.gov (United States)

    Huffman, R F; Henson, O W

    1993-01-01

    Acoustic stimuli near 60 kHz elicit pronounced resonance in the cochlea of the mustached bat (Pteronotus parnellii parnellii). The cochlear resonance frequency (CRF) is near the second harmonic, constant frequency (CF2) component of the bat's biosonar signals. Within narrow bands where CF2 and third harmonic (CF3) echoes are maintained, the cochlea has sharp tuning characteristics that are conserved throughout the central auditory system. The purpose of this study was to examine the effects of temperature-related shifts in the CRF on the tuning properties of neurons in the cochlear nucleus and inferior colliculus. Eighty-two single and multi-unit recordings were characterized in 6 awake bats with chronically implanted cochlear microphonic electrodes. As the CRF changed with body temperature, the tuning curves of neurons sharply tuned to frequencies near the CF2 and CF3 shifted with the CRF in every case, yielding a change in the unit's best frequency. The results show that cochlear tuning is labile in the mustached bat, and that this lability produces tonotopic shifts in the frequency response of central auditory neurons. Furthermore, results provide evidence of shifts in the frequency-to-place code within the sharply tuned CF2 and CF3 regions of the cochlea. In conjunction with the finding that biosonar emission frequency and the CRF shift concomitantly with temperature and flight, it is concluded that the adjustment of biosonar signals accommodates the shifts in cochlear and neural tuning that occur with active echolocation.

  20. RF Field Distribution Tuning of Drift Tube Linac

    Energy Technology Data Exchange (ETDEWEB)

    Kim, Han Sung; Kwon, Hyeok Jung; Jang, Ji Ho; Cho, Yong Sub [Korea Atomic Energy Research Institute, Daejeon (Korea, Republic of)

    2013-10-15

    To make a design field profile, we performed the RF tuning process for a 100-MeV drift tube linac (DTL) of Korea Multipurpose Accelerator Complex (KOMAC). The tuning process includes the field flatness tuning by using the slug tuners and the tilt sensitivity tuning by using the post couplers. The target values of the tuning process are like followings; - Field uniformity: better than 2% - Tilt sensitivity: less than 150%/MHz. During the tilt sensitivity tuning, we found that the slug tuners prevented the field stabilization if they were inserted too much. However, if the slug tuner positions were limited, then it was not possible to tune the DTL tank to the right resonant frequency. To solve the problem, we attached the tuning rings around each post couplers, which compensate the frequency gap caused by the slug tuner position limitations. We present the tuning process and results in this paper.

  1. Auditory tuning for spatial cues in the barn owl basal ganglia.

    Science.gov (United States)

    Cohen, Y E; Knudsen, E I

    1994-07-01

    1. The basal ganglia are known to contribute to spatially guided behavior. In this study, we investigated the auditory response properties of neurons in the barn owl paleostriatum augmentum (PA), the homologue of the mammalian striatum. The data suggest that the barn owl PA is specialized to process spatial cues and, like the mammalian striatum, is involved in spatial behavior. 2. Single- and multiunit sites were recorded extracellularly in ketamine-anesthetized owls. Spatial receptive fields were measured with a free-field sound source, and tuning for frequency and interaural differences in timing (ITD) and level (ILD) was assessed using digitally synthesized dichotic stimuli. 3. Spatial receptive fields measured at nine multiunit sites were tuned to restricted regions of space: tuning widths at half-maximum response averaged 22 +/- 9.6 degrees (mean +/- SD) in azimuth and 54 +/- 22 degrees in elevation. 4. PA sites responded strongly to broadband sounds. When frequency tuning could be measured (n = 145/201 sites), tuning was broad, averaging 2.7 kHz at half-maximum response, and tended to be centered near the high end of the owl's audible range. The mean best frequency was 6.2 kHz. 5. All PA sites (n = 201) were selective for both ITD and ILD. ITD tuning curves typically exhibited a single, large "primary" peak and often smaller, "secondary" peaks at ITDs ipsilateral and/or contralateral to the primary peak. Three indices quantified the selectivity of PA sites for ITD. The first index, which was the percent difference between the minimum and maximum response as a function of ITD, averaged 100 +/- 29%. The second index, which represented the size of the largest secondary peak relative to that of the primary peak, averaged 49 +/- 23%. The third index, which was the width of the primary ITD peak at half-maximum response, averaged only 66 +/- 35 microseconds. 6. The majority (96%; n = 192/201) of PA sites were tuned to a single "best" value of ILD. The widths of ILD

  2. Tuning Ice Nucleation with Supercharged Polypeptides

    NARCIS (Netherlands)

    Yang, Huige; Ma, Chao; Li, Kaiyong; Liu, Kai; Loznik, Mark; Teeuwen, Rosalie; van Hest, Jan C M; Zhou, Xin; Herrmann, Andreas; Wang, Jianjun

    2016-01-01

    Supercharged unfolded polypeptides (SUPs) are exploited for controlling ice nucleation via tuning the nature of charge and charge density of SUPs. The results show that positively charged SUPs facilitate ice nucleation, while negatively charged ones suppress it. Moreover, the charge density of the S

  3. TUNING OF GAUSSIAN STOCHASTIC-CONTROL SYSTEMS

    NARCIS (Netherlands)

    VANSCHUPPEN, JH

    1994-01-01

    A closed-loop system consisting of a control system and an adaptive controller will be called tuning for a specified control objective if the real system and the ideal system defined below achieve the same value for the control objective. The real system is the system consisting of the unknown contr

  4. Tuning controllers using the dual Youla parameterization

    DEFF Research Database (Denmark)

    Niemann, Hans Henrik; Stoustrup, Jakob

    2000-01-01

    This paper describes the application of the Youla parameterization of all stabilizing controllers and the dual Youla parameterization of all systems stabilized by a given controller in connection with tuning of controllers. In the uncertain case, it is shown that the use of the Youla...

  5. Self-tuning Integral Force Feedback

    NARCIS (Netherlands)

    Holterman, J.; de Vries, Theodorus J.A.; Samali, Bijan

    2000-01-01

    A self-tuning procedure is proposed for an active structural element with collocated sensing and actuation (a so-called ‘Smart Disc’). The procedure aims at optimal active damping by means of Integral Force Feedback control. In case the behavior of the structure to be damped may be described by a

  6. Dreams, mnemonics, and tuning for criticality.

    Science.gov (United States)

    Pearlmutter, Barak A; Houghton, Conor J

    2013-12-01

    According to the tuning-for-criticality theory, the essential role of sleep is to protect the brain from super-critical behaviour. Here we argue that this protective role determines the content of dreams and any apparent relationship to the art of memory is secondary to this.

  7. Natural Tuning: Towards A Proof of Concept

    CERN Document Server

    Dubovsky, Sergei; Mirbabayi, Mehrdad

    2013-01-01

    The cosmological constant problem and the absence of new natural physics at the electroweak scale, if confirmed by the LHC, may either indicate that the nature is fine-tuned or that a refined notion of naturalness is required. We construct a family of toy UV complete quantum theories providing a proof of concept for the second possibility. Low energy physics is described by a tuned effective field theory, which exhibits relevant interactions not protected by any symmetries and separated by an arbitrary large mass gap from the new "gravitational" physics, represented by a set of irrelevant operators. Nevertheless, the only available language to describe dynamics at all energy scales does not require any fine-tuning. The interesting novel feature of this construction is that UV physics is not described by a fixed point, but rather exhibits asymptotic fragility. Observation of additional unprotected scalars at the LHC would be a smoking gun for this scenario. Natural tuning also favors TeV scale unification.

  8. Tuning Wettability and Adhesion of Structured Surfaces

    Science.gov (United States)

    Badge, Ila

    Structured surfaces with feature size ranging from a few micrometers down to nanometers are of great interest in the applications such as design of anti-wetting surfaces, tissue engineering, microfluidics, filtration, microelectronic devices, anti-reflective coatings and reversible adhesives. A specific surface property demands particular roughness geometry along with suitable surface chemistry. Plasma Enhanced Chemical Vapor Deposition (PECVD) is a technique that offers control over surface chemistry without significantly affecting the roughness and thus, provides a flexibility to alter surface chemistry selectively for a given structured surface. In this study, we have used PECVD to fine tune wetting and adhesion properties. The research presented focuses on material design aspects as well as the fundamental understanding of wetting and adhesion phenomena of structured surfaces. In order to study the effect of surface roughness and surface chemistry on the surface wettability independently, we developed a model surface by combination of colloidal lithography and PECVD. A systematically controlled hierarchical roughness using spherical colloidal particles and surface chemistry allowed for quantitative prediction of contact angles corresponding to metastable and stable wetting states. A well-defined roughness and chemical composition of the surface enabled establishing a correlation between theory predictions and experimental measurements. We developed an extremely robust superhydrophobic surface based on Carbon-Nanotubes (CNT) mats. The surface of CNTs forming a nano-porous mesh was modified using PECVD to deposit a layer of hydrophobic coating (PCNT). The PCNT surface thus formed is superhydrophobic with almost zero contact angle hysteresis. We demonstrated that the PCNT surface is not wetted under steam condensation even after prolonged exposure and also continues to retain its superhydrophobicity after multiple frosting-defrosting cycles. The anti

  9. Procedures for Tuning a Multiresonator Photonic Filter

    Science.gov (United States)

    Matsko, Andrey; Savchenkov, Anatoliy; Strekalov, Dmitry; Maleki, Lute

    2007-01-01

    Two procedures have been devised for tuning a photonic filter that comprises multiple whispering-gallery mode (WGM) disk resonators. As used here, tuning signifies locking the filter to a specific laser frequency and configuring the filter to obtain a desired high-order transfer function. The main problem in tuning such a filter is how to select the correct relative loading of the resonators to realize a prescribed filter function. The first of the two procedures solves this problem. As temperature gradients develop during operation, the spectra of individual resonators tend to drift, primarily because of the thermorefractive effect. Thus, there arises the additional problem of how to adjust the tuning during operation to maintain the desired transfer function. The second of the two procedures solves this problem. To implement the procedures, it is necessary to incorporate the resonators into an apparatus like that of Figure 1. In this apparatus, the spectrum of each resonator can be adjusted individually, via the electro-optical effect, by adjusting a bias voltage applied to that resonator. In addition, the positions of the coupling prisms and resonators can be adjusted to increase or reduce the gaps between them, thereby reducing or increasing, respectively, the optical coupling between them. The optical power (Pi) in resonator i is monitored by use of a tracking photodiode. Another tracking diode monitors the power reflected from the input terminal (Pr), and still others monitor the input power (Pin) and output power (Po). The readings of these photodiodes are used to guide the tuning adjustments described in this paper.

  10. Pitch link loads reduction of variable speed rotors by variable tuning frequency fluidlastic isolators

    Institute of Scientific and Technical Information of China (English)

    Han Dong

    2015-01-01

    To reduce the pitch link loads of variable speed rotors, variable tuning frequency fluid-lastic isolators are proposed. This isolator utilizes the variation of centrifugal force due to the change of rotor speed to change the tuning port area ratio, which can change the tuning frequency of the isolator. A rotor model including the model of fluidlastic isolator is coupled with a fuselage model to predict the steady responses of the rotor system in forward flight. The aeroelastic analyses indicate that distinct performance improvement in pitch link load control can be achieved by the utilization of variable frequency isolators compared with the constant tuning frequency isolators. The 4/rev (per revolution) pitch link load is observed to be reduced by 87.6%compared with the increase of 56.3%by the constant frequency isolator, when the rotor speed is reduced by 16.7%. The isolation ability at different rotor speeds in different flight states is investigated. To achieve overall load reduction within the whole range of rotor speed, the strategy of the variation of tuning frequency is adjusted. The results indicate that the 4/rev pitch link load within the whole rotor speed range is decreased.

  11. Pitch link loads reduction of variable speed rotors by variable tuning frequency fluidlastic isolators

    Directory of Open Access Journals (Sweden)

    Han Dong

    2015-10-01

    Full Text Available To reduce the pitch link loads of variable speed rotors, variable tuning frequency fluidlastic isolators are proposed. This isolator utilizes the variation of centrifugal force due to the change of rotor speed to change the tuning port area ratio, which can change the tuning frequency of the isolator. A rotor model including the model of fluidlastic isolator is coupled with a fuselage model to predict the steady responses of the rotor system in forward flight. The aeroelastic analyses indicate that distinct performance improvement in pitch link load control can be achieved by the utilization of variable frequency isolators compared with the constant tuning frequency isolators. The 4/rev (per revolution pitch link load is observed to be reduced by 87.6% compared with the increase of 56.3% by the constant frequency isolator, when the rotor speed is reduced by 16.7%. The isolation ability at different rotor speeds in different flight states is investigated. To achieve overall load reduction within the whole range of rotor speed, the strategy of the variation of tuning frequency is adjusted. The results indicate that the 4/rev pitch link load within the whole rotor speed range is decreased.

  12. Tuning Mazda B6 Engine for Sports Competitions

    Science.gov (United States)

    Lukács, E.; Polóni, M.

    2011-12-01

    Improving output parameters of the Mazda B6 combustion engine from the vehicle Mazda 323 for amateur "hill climb" and "rally" competitions has been analysed. Tuning of such an engine for sport competitions means the optimisation of its parameters at the lowest possible economic costs, within the revolution range 4000 - 6000 min-1, where the engine during competition works most often. With the help of the program Lotus Engine Simulations, the construction of the exhaust manifold has been optimised, together with valve timing and other adjustments, listed in the work, on output parameters of the engine. The optimum combinations of parameters were experimentally verified on a chassis dynamometer. Final adaptations have led within the previously specified range of revolutions to an improvement between 5 and 22% in power and torque.

  13. Tuning upconversion through energy migration in core-shell nanoparticles

    KAUST Repository

    Wang, Feng

    2011-10-23

    Photon upconversion is promising for applications such as biological imaging, data storage or solar cells. Here, we have investigated upconversion processes in a broad range of gadolinium-based nanoparticles of varying composition. We show that by rational design of a core-shell structure with a set of lanthanide ions incorporated into separated layers at precisely defined concentrations, efficient upconversion emission can be realized through gadolinium sublattice-mediated energy migration for a wide range of lanthanide activators without long-lived intermediary energy states. Furthermore, the use of the core-shell structure allows the elimination of deleterious cross-relaxation. This effect enables fine-tuning of upconversion emission through trapping of the migrating energy by the activators. Indeed, the findings described here suggest a general approach to constructing a new class of luminescent materials with tunable upconversion emissions by controlled manipulation of energy transfer within a nanoscopic region. © 2011 Macmillan Publishers Limited. All rights reserved.

  14. SEMICONDUCTOR INTEGRATED CIRCUITS: A reconfigurable OTA-C baseband filter with wide digital tuning for GNSS receivers

    Science.gov (United States)

    Wenguang, Pan; Chengyan, Ma; Yebing, Gan; Tianchun, Ye

    2010-09-01

    The design of a digitally-tunable sixth-order reconfigurable OTA-C filter in a 0.18-μm RFCMOS process is proposed. The filter can be configured as a complex band pass filter or two real low pass filters. An improved digital automatic frequency tuning scheme based on the voltage controlled oscillator technique is adopted to compensate for process variations. An extended tuning range (above 8:1) is obtained by using widely continuously tunable transcon-ductors based on digital techniques. In the complex band pass mode, the bandwidth can be tuned from 3 to 24 MHz and the center frequency from 3 to 16 MHz.

  15. Self-Tuning Speed Regulator for CVC Induction Motor Drive

    DEFF Research Database (Denmark)

    Bidstrup, N.; Rasmussen, Henrik; Knudsen, Torben

    1994-01-01

    A self-tuning speed regulator for a current vector controlled induction motor drive has been designed.......A self-tuning speed regulator for a current vector controlled induction motor drive has been designed....

  16. Application of genetic algorithms to tuning fuzzy control systems

    Science.gov (United States)

    Espy, Todd; Vombrack, Endre; Aldridge, Jack

    1993-01-01

    Real number genetic algorithms (GA) were applied for tuning fuzzy membership functions of three controller applications. The first application is our 'Fuzzy Pong' demonstration, a controller that controls a very responsive system. The performance of the automatically tuned membership functions exceeded that of manually tuned membership functions both when the algorithm started with randomly generated functions and with the best manually-tuned functions. The second GA tunes input membership functions to achieve a specified control surface. The third application is a practical one, a motor controller for a printed circuit manufacturing system. The GA alters the positions and overlaps of the membership functions to accomplish the tuning. The applications, the real number GA approach, the fitness function and population parameters, and the performance improvements achieved are discussed. Directions for further research in tuning input and output membership functions and in tuning fuzzy rules are described.

  17. Tuning the iridescence of chiral nematic cellulose nanocrystals and mesoporous silica films by substrate variation.

    Science.gov (United States)

    Nguyen, Thanh-Dinh; Hamad, Wadood Y; MacLachlan, Mark J

    2013-12-14

    We have discovered that the self-assembly of cellulose nanocrystals (CNCs) into chiral nematic phases varies significantly with the substrate and evaporation rate. These variables allow the reflectance peak of iridescent chiral nematic films of CNCs and mesoporous silica templated from CNCs to be tuned over a wide range of wavelengths.

  18. Evolutionary Computation Applied to the Tuning of MEMS Gyroscopes

    Science.gov (United States)

    Keymeulen, Didier; Fink, Wolfgang; Ferguson, Michael I.; Peay, Chris; Oks, Boris; Terrile, Richard; Yee, Karl

    2005-01-01

    We propose a tuning method for MEMS gyroscopes based on evolutionary computation to efficiently increase the sensitivity of MEMS gyroscopes through tuning and, furthermore, to find the optimally tuned configuration for this state of increased sensitivity. The tuning method was tested for the second generation JPL/Boeing Post-resonator MEMS gyroscope using the measurement of the frequency response of the MEMS device in open-loop operation.

  19. Tuning of light-graphene interactions

    DEFF Research Database (Denmark)

    Xiao, Sanshui

    — Graphene opens up for novel optoelectronic applications thanks to its high carrier mobility, ultra-large absorption bandwidth, and extremely fast material response. In particular, the opportunity to control optoelectronic properties through Fermi-level tuning enables electrooptical modulation......, optical-optical switching, and other optoelectronics applications. Except for the statistic gating and chemical doping, the Fermi level of graphene can also be optically tuned. With the aid of external optical pumping, electrons can be excited in the substrate, then move to the graphene layer, leading...... to the electrical doping in graphene. In this talk, I will firstly discuss how the graphene property changes when applying the optical pumping with different incident power. Then I will discuss graphene-silicon microring devices with having a high modulation depth and with a relatively low bias voltage. Finally, I...

  20. Energetic Tuning in Spirocyclic Conjugated Polymers

    Directory of Open Access Journals (Sweden)

    Hugo Bronstein

    2016-01-01

    Full Text Available Precise control of the energy levels in a conjugated polymer is the key to allowing their exploitation in optoelectronic devices. The introduction of spirocycles into conjugated polymers has traditionally been used to enhance their solid state microstructure. Here we present a highly novel method of energetic tuning through the use of electronically active spirocyclic systems. By modifying the size and oxidation state of a heteroatom in an orthogonal spirocycle we demonstrate energetic fine tuning in both the absorption and emission of a conjugated polymer. Furthermore, the synthesis of highly novel triplet-decker spirocyclic conjugated polymers is presented. This new method of energetic manipulation in a conjugated polymer paves the way for future application targeted synthesis of polymers with electronically active spirocycles.

  1. Stabilization of betatron tune in Indus-2

    CERN Document Server

    Jena, Saroj; Agrawal, R K; Ghodke, A D; Fatnani, Pravin; Puntambekar, T A

    2013-01-01

    Indus-2 is a synchrotron radiation source which is operational at RRCAT, Indore; India. It is essentially pertinent in any synchrotron radiation facility to store the electron beam without beam loss. During the day to day operation of Indus-2 storage ring difficulty was being faced in accumulating higher beam current. After examining, it was found that the working point was shifting from its desired value during accumulation. For smooth beam accumulation, a fixed desired tune in both horizontal and vertical plane plays a great role in avoiding the beam loss via resonance process. This demanded a betatron tune feedback system to be put in storage ring and after putting ON this feedback, the beam accumulation was smooth. The details of this feedback and its working principle are described in this paper.

  2. Synthetic phase tuning of guided waves.

    Science.gov (United States)

    Wooh, S C; Shi, Y

    2001-01-01

    A novel method has been developed to generate and manipulate multi-mode guided waves. This technique uses a linear phased array whose elements are activated according to a prescribed time delay profile obtained from the dispersion curves. It is shown that a desired guided wave mode can be tuned by synthetically constructing a virtual wave from individually acquired waveform data. In addition to the development of such a synthetic phase tuning (SPT) technique, a pseudo pulse-echo (PPE) operation scheme is also developed for nondestructive testing. Experimental results are compared with those obtained by more traditional techniques using variable angle wedges and array transducers. It was shown that the new technique is convenient, robust, and flexible in utilizing multi-mode guided waves for nondestructive evaluation (NDE). It is a dynamic method that can produce desired guided wave modes propagating in the desired direction without any mechanical alignment. The advantages and limitations of the technique are addressed.

  3. Automatic Tuning of Interactive Perception Applications

    CERN Document Server

    Zhu, Qian; Mummert, Lily; Pillai, Padmanabhan

    2012-01-01

    Interactive applications incorporating high-data rate sensing and computer vision are becoming possible due to novel runtime systems and the use of parallel computation resources. To allow interactive use, such applications require careful tuning of multiple application parameters to meet required fidelity and latency bounds. This is a nontrivial task, often requiring expert knowledge, which becomes intractable as resources and application load characteristics change. This paper describes a method for automatic performance tuning that learns application characteristics and effects of tunable parameters online, and constructs models that are used to maximize fidelity for a given latency constraint. The paper shows that accurate latency models can be learned online, knowledge of application structure can be used to reduce the complexity of the learning task, and operating points can be found that achieve 90% of the optimal fidelity by exploring the parameter space only 3% of the time.

  4. Quartz tuning fork based microwave impedance microscopy

    Science.gov (United States)

    Cui, Yong-Tao; Ma, Eric Yue; Shen, Zhi-Xun

    2016-06-01

    Microwave impedance microscopy (MIM), a near-field microwave scanning probe technique, has become a powerful tool to characterize local electrical responses in solid state samples. We present the design of a new type of MIM sensor based on quartz tuning fork and electrochemically etched thin metal wires. Due to a higher aspect ratio tip and integration with tuning fork, such design achieves comparable MIM performance and enables easy self-sensing topography feedback in situations where the conventional optical feedback mechanism is not available, thus is complementary to microfabricated shielded stripline-type probes. The new design also enables stable differential mode MIM detection and multiple-frequency MIM measurements with a single sensor.

  5. I Tune, You Tube, We Rule

    Science.gov (United States)

    Shida, R. Y.; Gater, W.

    2007-10-01

    The website YouTube was created in 2005 and has rapidly become one of the most popular entertainment websites on the internet. It is riding the online video wave today like few other online companies and is currently more popular than the video sections of either Yahoo or Google. iTunes, a digital media application created by Apple in 2001, where one can download and play music and videos, has had a similar success. There is little doubt that they both represent important communication channels in a world heavily influenced by online media, especially among teenagers and young adults. As science communicators we can use this direct route to a younger audience to our advantage. This article aims to give a taste of these applications with a few selected examples demonstrating that both YouTube and iTunes are excellent tools to teach and inspire the general public.

  6. Strings on a Violin: Location Dependence of Frequency Tuning in Active Dendrites

    Science.gov (United States)

    Das, Anindita; Rathour, Rahul K.; Narayanan, Rishikesh

    2017-01-01

    Strings on a violin are tuned to generate distinct sound frequencies in a manner that is firmly dependent on finger location along the fingerboard. Sound frequencies emerging from different violins could be very different based on their architecture, the nature of strings and their tuning. Analogously, active neuronal dendrites, dendrites endowed with active channel conductances, are tuned to distinct input frequencies in a manner that is dependent on the dendritic location of the synaptic inputs. Further, disparate channel expression profiles and differences in morphological characteristics could result in dendrites on different neurons of the same subtype tuned to distinct frequency ranges. Alternately, similar location-dependence along dendritic structures could be achieved through disparate combinations of channel profiles and morphological characteristics, leading to degeneracy in active dendritic spectral tuning. Akin to strings on a violin being tuned to different frequencies than those on a viola or a cello, different neuronal subtypes exhibit distinct channel profiles and disparate morphological characteristics endowing each neuronal subtype with unique location-dependent frequency selectivity. Finally, similar to the tunability of musical instruments to elicit distinct location-dependent sounds, neuronal frequency selectivity and its location-dependence are tunable through activity-dependent plasticity of ion channels and morphology. In this morceau, we explore the origins of neuronal frequency selectivity, and survey the literature on the mechanisms behind the emergence of location-dependence in distinct forms of frequency tuning. As a coda to this composition, we present some future directions for this exciting convergence of biophysical mechanisms that endow a neuron with frequency multiplexing capabilities.

  7. TeraHz tuning of whispering gallery modes in a PDMS, stand-alone, stretchable microsphere

    CERN Document Server

    Madugani, Ramgopal; Ward, Jonathan M; Riordan, John Daniel; Coppola, Sara; Vespini, Veronica; Grilli, Simonetta; Finizio, Andrea; Ferraro, Pietro; Chormaic, Síle Nic

    2012-01-01

    We report on tuning the optical whispering gallery modes in a poly dimethyl siloxane-based (PDMS) microsphere resonator by more than a THz. The PDMS microsphere system consists of a solid spherical resonator directly formed with double stems on either side. The stems act like tie-rods for simple mechanical stretching of the microresonator over tens of microns, resulting in tuning of the whispering gallery modes by one free spectral range. Further investigations demonstrate that the whispering gallery mode shift has a higher sensitivity (0.13 nm/{\\mu}N) to an applied force when the resonator is in its maximally stretched state compared to its relaxed state.

  8. A quenched study of the Schroedinger functional with chirally rotated boundary conditions. Non-preturbative tuning

    Energy Technology Data Exchange (ETDEWEB)

    Lopez, J. Gonzalez [Humboldt-Universitaet, Berlin (Germany). Inst. fuer Physik; Deutsches Elektronen-Synchrotron (DESY), Zeuthen (Germany); Jansen, K. [Deutsches Elektronen-Synchrotron (DESY), Zeuthen (Germany); Renner, D.B. [Jefferson Lab, Newport News, VA (United States); Shindler, A. [Humboldt-Universitaet, Berlin (Germany). Inst. fuer Physik

    2012-08-23

    The use of chirally rotated boundary conditions provides a formulation of the Schroedinger functional that is compatible with automatic O(a) improvement of Wilson fermions up to O(a) boundary contributions. The elimination of bulk O(a) effects requires the non-perturbative tuning of the critical mass and one additional boundary counterterm. We present the results of such a tuning in a quenched setup for several values of the renormalized gauge coupling, from perturbative to nonperturbative regimes, and for a range of lattice spacings. We also check that the correct boundary conditions and symmetries are restored in the continuum limit. (orig.)

  9. Charged particle multiplicities in inelastic pp interactions with ATLAS and the ATLAS Minimum Bias Tune 1

    CERN Document Server

    Brandt, G; The ATLAS collaboration

    2010-01-01

    Measurements of the charged particle multiplicity produced in proton-proton collisions at the LHC at centre-of-mass energies $sqrt{s}=0.9$~TeV and $7$~TeV recorded with the ATLAS detector are presented. Distributions are measured for events with at least one charged particle $n_{ch}geq1$ in the kinematic range $|eta|<2.5$ and $p_T>500$~MeV. The measurement is also constrained to a diffraction-limited phasespace $n_{ch} geq 6$ and used for the production of the first py6 tune to LHC data, the ATLAS Minimum Bias Tune~1 (AMBT1).

  10. An effective frequency domain approach to tuning non-PID controllers for high performance.

    Science.gov (United States)

    Wang, Qing-Guo; Ru, He; Huang, Xiao-Gang

    2002-01-01

    In this paper, a new tuning method is proposed for the design of non-PID controllers for complex processes to achieve high performance. Compared with the existing PID tuning methods, the proposed non-PID controller design method can yield better performance for a wide range of complex processes. A suitable objective transfer function for the closed-loop system is chosen according to process characteristics. The corresponding ideal controller is derived. Model reduction is applied to fit the ideal controller into a much simpler and realizable form. Stability analysis is given and simulation examples are provided to demonstrate the effectiveness of the proposed method.

  11. PI tuning for large dead-time processes with a new robustness specification

    Institute of Scientific and Technical Information of China (English)

    徐江华; 邵惠鹤

    2004-01-01

    A simple PI controller tuning method for large dead-time processes is presented. First, a first-order plus dead-time model is identified on the basis of relay feedback experiments, which Nyquist curve is very close to that of large dead-time processes over a wide frequency range. With the model available, PI controller is designed with a new robust specification. Simulation examples show the effectiveness and feasibility of the presented PI tuning method for large dead-time processes.

  12. A quenched study of the Schroedinger functional with chirally rotated boundary conditions. Non-preturbative tuning

    Energy Technology Data Exchange (ETDEWEB)

    Lopez, J. Gonzalez [Humboldt-Universitaet, Berlin (Germany). Inst. fuer Physik; Deutsches Elektronen-Synchrotron (DESY), Zeuthen (Germany); Jansen, K. [Deutsches Elektronen-Synchrotron (DESY), Zeuthen (Germany); Renner, D.B. [Jefferson Lab, Newport News, VA (United States); Shindler, A. [Humboldt-Universitaet, Berlin (Germany). Inst. fuer Physik

    2012-08-23

    The use of chirally rotated boundary conditions provides a formulation of the Schroedinger functional that is compatible with automatic O(a) improvement of Wilson fermions up to O(a) boundary contributions. The elimination of bulk O(a) effects requires the non-perturbative tuning of the critical mass and one additional boundary counterterm. We present the results of such a tuning in a quenched setup for several values of the renormalized gauge coupling, from perturbative to nonperturbative regimes, and for a range of lattice spacings. We also check that the correct boundary conditions and symmetries are restored in the continuum limit. (orig.)

  13. Fast continuous tuning of terahertz quantum-cascade lasers by rear-facet illumination

    Energy Technology Data Exchange (ETDEWEB)

    Hempel, Martin, E-mail: hempel@pdi-berlin.de; Röben, Benjamin; Schrottke, Lutz; Grahn, Holger T. [Paul-Drude-Institut für Festkörperelektronik, Leibniz-Institut im Forschungsverbund Berlin e. V., Hausvogteiplatz 5–7, 10117 Berlin (Germany); Hübers, Heinz-Wilhelm [Institute of Optical Sensor Systems, German Aerospace Center (DLR), Rutherfordstr. 2, 12489 Berlin (Germany); Department of Physics, Humboldt-Universität zu Berlin, Newtonstr. 15, 12489 Berlin (Germany)

    2016-05-09

    GaAs-based terahertz quantum-cascade lasers (QCLs) are continuously tuned in their emission frequency by illuminating the rear facet with a near-infrared, high-power diode laser. For QCLs emitting around 3.1 THz, the maximum tuning range amounts to 2.8 GHz for continuous-wave operation at a heat sink temperature of 55 K, while in pulsed mode 9.1 and 8.0 GHz are achieved at 35 and 55 K, respectively.

  14. A high dynamic range programmable CMOS front-end filter with a tuning range from 1850 to 2400 MHz

    DEFF Research Database (Denmark)

    Christensen, Kåre Tais; Lee, Thomas H.; Bruun, Erik

    2005-01-01

    This paper presents a highly programmable front-end filter and amplifier intended to replace SAW filters and low noise amplifiers (LNA) in multi-mode direct conversion radio receivers. The filter has a 42 MHz bandwidth, is tunable from 1850 to 2400 MHz, achieves a 5.8 dB NF, -25 dBm in-band 1-d...

  15. A high dynamic range programmable CMOS front-end filter with a tuning range from 1850 to 2400 MHz

    DEFF Research Database (Denmark)

    Christensen, Kåre Tais; Lee, Thomas H.; Bruun, Erik

    2005-01-01

    This paper presents a highly programmable front-end filter and amplifier intended to replace SAW filters and low noise amplifiers (LNA) in multi-mode direct conversion radio receivers. The filter has a 42 MHz bandwidth, is tunable from 1850 to 2400 MHz, achieves a 5.8 dB NF, -25 dBm in-band 1-dB ...

  16. How do bacteria tune translation efficiency?

    OpenAIRE

    Li, Gene-Wei

    2015-01-01

    Bacterial proteins are translated with precisely determined rates to meet cellular demand. In contrast, efforts to express recombinant proteins in bacteria are often met with large unpredictability in their levels of translation. The disconnect between translation of natural and synthetic mRNA stems from the lack of understanding of the strategy used by bacteria to tune translation efficiency. The development of array-based oligonucleotide synthesis and ribosome profiling provides new approac...

  17. Turbine blade with tuned damping structure

    Energy Technology Data Exchange (ETDEWEB)

    Campbell, Christian X.; Messmann, Stephen J.

    2015-09-01

    A turbine blade is provided comprising: a root; an airfoil comprising an external wall extending radially from the root and having a radially outermost portion; and a damping structure. The external wall may comprise first and second side walls joined together to define an inner cavity of the airfoil. The damping structure may be positioned within the airfoil inner cavity and coupled to the airfoil so as to define a tuned mass damper.

  18. Schottky signal analysis: tune and chromaticity computation

    CERN Document Server

    Chanon, Ondine

    2016-01-01

    Schottky monitors are used to determine important beam parameters in a non-destructive way. The Schottky signal is due to the internal statistical fluctuations of the particles inside the beam. In this report, after explaining the different components of a Schottky signal, an algorithm to compute the betatron tune is presented, followed by some ideas to compute machine chromaticity. The tests have been performed with offline and/or online LHC data.

  19. Feature Weight Tuning for Recursive Neural Networks

    OpenAIRE

    2014-01-01

    This paper addresses how a recursive neural network model can automatically leave out useless information and emphasize important evidence, in other words, to perform "weight tuning" for higher-level representation acquisition. We propose two models, Weighted Neural Network (WNN) and Binary-Expectation Neural Network (BENN), which automatically control how much one specific unit contributes to the higher-level representation. The proposed model can be viewed as incorporating a more powerful c...

  20. Energetic tuning in spirocyclic conjugated polymers

    OpenAIRE

    Hugo Bronstein; Frank D. King

    2016-01-01

    Precise control of the energy levels in a conjugated polymer is the key to allowing their exploitation in optoelectronic devices. The introduction of spirocycles into conjugated polymers has traditionally been used to enhance their solid state microstructure. Here we present a highly novel method of energetic tuning through the use of electronically active spirocyclic systems. By modifying the size and oxidation state of a heteroatom in an orthogonal spirocycle we demonstrate energetic fine t...

  1. Model-reference robust tuning of PID controllers

    CERN Document Server

    Alfaro, Victor M

    2016-01-01

    This book presents a unified methodology for the design of PID controllers that encompasses the wide range of different dynamics to be found in industrial processes. This is extended to provide a coherent way of dealing with the tuning of PID controllers. The particular method at the core of the book is the so-called model-reference robust tuning (MoReRT), developed by the authors. MoReRT constitutes a novel and powerful way of thinking of a robust design and taking into account the usual design trade-offs encountered in any control design problem. The book starts by presenting the different two-degree-of-freedom PID control algorithm variations and their conversion relations as well as the indexes used for performance, robustness and fragility evaluation:the bases of the proposed model. Secondly, the MoReRT design methodology and normalized controlled process models and controllers used in the design are described in order to facilitate the formulation of the different design problems and subsequent derivati...

  2. Zirconium alloys produced by recycling zircaloy tunings

    Energy Technology Data Exchange (ETDEWEB)

    Gamba, N.S. [Instituto de Investigaciones en Catálisis y Petroquímica, INCAPE (FIQ, UNL–CONICET), Santiago del Estero 2829, 3000 Santa Fe (Argentina); Carbajal-Ramos, I.A. [Centro Atómico Bariloche, CNEA e Instituto Balseiro, Universidad Nacional de Cuyo, Av. Bustillo 9500, 8400 Bariloche (Argentina); Ulla, M.A.; Pierini, B.T. [Instituto de Investigaciones en Catálisis y Petroquímica, INCAPE (FIQ, UNL–CONICET), Santiago del Estero 2829, 3000 Santa Fe (Argentina); Gennari, F.C., E-mail: gennari@cab.cnea.gov.ar [Centro Atómico Bariloche, CNEA e Instituto Balseiro, Universidad Nacional de Cuyo, Av. Bustillo 9500, 8400 Bariloche (Argentina)

    2013-11-25

    Highlights: •Zr–Ti alloys were successfully produced by two-step procedure. •Zircaloy tunings were used as a valuable source of Zr. •Zircaloy tunings and Ti powders was milled under hydrogen to produce hydride powders. •Hydride powders were decomposed by heating at 900 °C to synthesize the Zr-based alloy. •The procedure could be extended to the production of other Zr-based alloys. -- Abstract: Zircaloy chips were recycled to successfully produce Zr–Ti alloys with bcc structure and different compositions. The procedure developed involves two steps. First, the reactive mechanical alloying (RMA) of the zircaloy tunings and Ti powders was performed to produce metal hydride powders, with a high refinement of the microstructure and a Zr–Ti homogeneous composition. Second, the metal hydride powders were thermally decomposed by heating up to 900 °C to synthesize the Zr-based alloy with a selected composition. The change in the nature of the powders from ductile to brittle during milling avoids both cold working phenomena between the metals and the use of a control agent. A minimum milling time is necessary to produce the solid solution with the selected composition. The microstructure and structure of the final alloys obtained was studied. The present procedure could be extended to the production of Zr-based alloys with the addition of other metals different from Ti.

  3. Tuning your priors to the world.

    Science.gov (United States)

    Feldman, Jacob

    2013-01-01

    The idea that perceptual and cognitive systems must incorporate knowledge about the structure of the environment has become a central dogma of cognitive theory. In a Bayesian context, this idea is often realized in terms of "tuning the prior"-widely assumed to mean adjusting prior probabilities so that they match the frequencies of events in the world. This kind of "ecological" tuning has often been held up as an ideal of inference, in fact defining an "ideal observer." But widespread as this viewpoint is, it directly contradicts Bayesian philosophy of probability, which views probabilities as degrees of belief rather than relative frequencies, and explicitly denies that they are objective characteristics of the world. Moreover, tuning the prior to observed environmental frequencies is subject to overfitting, meaning in this context overtuning to the environment, which leads (ironically) to poor performance in future encounters with the same environment. Whenever there is uncertainty about the environment-which there almost always is-an agent's prior should be biased away from ecological relative frequencies and toward simpler and more entropic priors.

  4. Uncertainty, fear and whistling happy tunes.

    Science.gov (United States)

    Wallis, Katharine; Wallis, Katherine

    2009-03-01

    Uncertainty in medical practice is ineradicable, despite great scientific advances over the last century. Uncertainty provokes fear, not just in patients but also in doctors. Patients cope with theirfear by seeking the advice and reassurance of doctors; doctors, on the other hand, cope by denial and self-deception. But today, in this scientific, truth-seeking age doctors are encouraged to share their uncertainty with patients in order to 'empower' patients and improve doctor-patient relations. While in theory doctors might agree with this approach, in practice they continue to deny it and instead whistle happy tunes--deceiving both themselves and their patients. A disclosure of uncertainty requires an acknowledgement of uncertainty and, in practice, the ability of doctors to acknowledge and to tolerate uncertainty is limited. Whenever I feel afraid, I hold my head erect. And whistle a happy tune, So no one will suspect I'm afraid. While shivering in my shoes, I strike a careless pose. And whistle a happy tune, And no one ever knows. I'm afraid. The result of this deception, Is very strange to tell. For when I fool the people I fear, I fool myself as well!

  5. Tuned Chamber Core Panel Acoustic Test Results

    Science.gov (United States)

    Schiller, Noah H.; Allen, Albert R.

    2016-01-01

    This report documents acoustic testing of tuned chamber core panels, which can be used to supplement the low-frequency performance of conventional acoustic treatment. The tuned chamber core concept incorporates low-frequency noise control directly within the primary structure and is applicable to sandwich constructions with a directional core, including corrugated-, truss-, and fluted-core designs. These types of sandwich structures have long, hollow channels (or chambers) in the core. By adding small holes through one of the facesheets, the hollow chambers can be utilized as an array of low-frequency acoustic resonators. These resonators can then be used to attenuate low-frequency noise (below 400 Hz) inside a vehicle compartment without increasing the weight or size of the structure. The results of this test program demonstrate that the tuned chamber core concept is effective when used in isolation or combined with acoustic foam treatments. Specifically, an array of acoustic resonators integrated within the core of the panels was shown to improve both the low-frequency absorption and transmission loss of the structure in targeted one-third octave bands.

  6. Multiple critical velocities in oscillatory flow of superfluid 4He due to quartz tuning forks

    Science.gov (United States)

    Schmoranzer, D.; Jackson, M. J.; Tsepelin, V.; Poole, M.; Woods, A. J.; Človečko, M.; Skrbek, L.

    2016-12-01

    We report recent investigations into the transition to turbulence in superfluid 4He, realized experimentally by measuring the drag forces acting on two custom-made quartz tuning forks with fundamental resonances at 6.5 kHz and 55.5 kHz, in the temperature range 10 mK to 2.17 K. In pure superfluid in the zero temperature limit, three distinct critical velocities were observed with both tuning forks. We discuss the significance of all critical velocities and associate the third critical velocity reported here with the development of large vortical structures in the flow, which thus starts to mimic turbulence in classical fluids. The interpretation of our results is directly linked to previous experimental work with oscillators such as tuning forks, grids, and vibrating wires, focusing on the behavior of purely superfluid 4He at very low temperatures.

  7. Optical tuning of three-dimensional photonic crystals fabricated by femtosecond direct writing

    Science.gov (United States)

    McPhail, Dennis; Straub, Martin; Gu, Min

    2005-08-01

    In this letter, we report on an optically tunable three-dimensional photonic crystal that exhibits main gaps in the 3-4μm range. The photonic crystal is manufactured via a femtosecond direct writing technique. Optical tuning is achieved by a luminary polling technique with a low-power polarized laser beam. The refractive index variation resulting from liquid-crystal rotation causes a shift in the photonic band gap of up to 65 nm with an extinction of transmission of up to 70% in the stacking direction. Unlike other liquid-crystal tuning techniques where a pregenerated structure is infiltrated, this optical tuning method is a one-step process that allows arbitrary structures to be written into a solid liquid-crystal-polymer composite and leads to a high dielectric contrast.

  8. Controlling the Limit-Cycle of the Ziegler Column via a Tuned Piezoelectric Damper

    Directory of Open Access Journals (Sweden)

    Francesco D’Annibale

    2015-01-01

    Full Text Available This paper is about the nonlinear analysis of a piezoelectric controlled Ziegler column. The piezoelectric controller, here referred to as Tuned Piezoelectric Damper (TPD, possesses evanescent characteristics and, moreover, it is tuned to the first natural frequency of the mechanical system, thus resembling the well-known Tuned Mass Damper. This means that the flow of energy between mechanical and electrical subsystems is driven by the resonance (Den Hartog principle and magnified by the singularity of the evanescent electrical characteristics. Numerical simulations, showing how the proposed control strategy is effective in increasing the linear stability domain and decreasing the amplitude of the limit-cycles in the postcritical range, are presented.

  9. Controller tuning with evolutionary multiobjective optimization a holistic multiobjective optimization design procedure

    CERN Document Server

    Reynoso Meza, Gilberto; Sanchis Saez, Javier; Herrero Durá, Juan Manuel

    2017-01-01

    This book is devoted to Multiobjective Optimization Design (MOOD) procedures for controller tuning applications, by means of Evolutionary Multiobjective Optimization (EMO). It presents developments in tools, procedures and guidelines to facilitate this process, covering the three fundamental steps in the procedure: problem definition, optimization and decision-making. The book is divided into four parts. The first part, Fundamentals, focuses on the necessary theoretical background and provides specific tools for practitioners. The second part, Basics, examines a range of basic examples regarding the MOOD procedure for controller tuning, while the third part, Benchmarking, demonstrates how the MOOD procedure can be employed in several control engineering problems. The fourth part, Applications, is dedicated to implementing the MOOD procedure for controller tuning in real processes.

  10. Experimental studies of a zeeman-tuned xenon laser differential absorption apparatus.

    Science.gov (United States)

    Linford, G J

    1973-06-01

    A Zeeman-tuned cw xenon laser differential absorption device is described. The xenon laser was tuned by axial magnetic fields up to 5500 G generated by an unusually large water-cooled dc solenoid. Xenon laser lines at 3.37 micro, 3.51 micro, and 3.99 micro were tuned over ranges of 6 A, 6 A, and 11 A, respectively. To date, this apparatus has been used principally to study the details of formaldehyde absorption lines lying near the 3 .508-micro xenon laser transition. These experiments revealed that the observed absorption spectrum of formaldehyde exhibits a sufficiently unique spectral structure that the present technique may readily be used to measure relative concentrations of formaldehyde in samples of polluted air.

  11. Investigation of double-mode operation and fast fine tuning properties of a grating-coupled external cavity diode laser configuration

    Science.gov (United States)

    Bayrakli, Ismail

    2017-01-01

    Double-mode operation and fast piezo fine tuning properties of a gain chip on a thermoelectric cooler in an external cavity are investigated. A widely course double-mode tuning range of 120 nm for the spectral range between 1470 and 1590 nm is achieved by rotating the diffraction gratings forming a double Littrow-type configuration. A fast piezo fine tuning range over 7cm-1 (1.5 nm, 210 GHz) in a single-mode operation is obtained by scanning the external cavity length with scan rates up to 0.5 kHz.

  12. Energy harvesting from a multifrequency response of a tuned bending-torsion system

    Science.gov (United States)

    Abdelkefi, A.; Nayfeh, A. H.; Hajj, M. R.; Najar, F.

    2012-07-01

    We investigate the benefits of tuning the frequencies of an energy harvester to extract more energy from a base excitation that comprises three frequency components. The energy harvester is composed of a unimorph cantilever beam with asymmetric tip masses. By adjusting the asymmetry of the tip masses, we can tune this beam-mass structure to harvest energy from multifrequency components of a base excitation. We model the beam using the Euler-Bernoulli beam theory and use the first three global mode shapes of the harvester in a Galerkin procedure to derive a reduced-order model describing its response. We derive an exact analytical solution for the tip deflection, twisting angle, voltage output, and harvested electrical power. Using this solution, we investigate the advantages of harvesting energy from a response that contains multifrequencies in comparison to a response that contains a single frequency by tuning only the fundamental frequency. The advantages of this bending-torsion energy harvester and the effect of its tuning are investigated for different short- and open-circuit configurations. The results show that, through a proper tuning of this bending-torsion harvester, the harvested power can be increased significantly and it can be made to cover a wide range of electrical load resistances.

  13. Size of the Organic Cation Tunes the Band Gap of Colloidal Organolead Bromide Perovskite Nanocrystals.

    Science.gov (United States)

    Mittal, Mona; Jana, Atanu; Sarkar, Sagar; Mahadevan, Priya; Sapra, Sameer

    2016-08-18

    A few approaches have been employed to tune the band gap of colloidal organic-inorganic trihalide perovskites (OTPs) nanocrystals by changing the halide anion. However, to date, there is no report of electronic structure tuning of perovskite NCs upon changing the organic cation. We report here, for the first time, the room temperature colloidal synthesis of (EA)x(MA)1-xPbBr3 nanocrystals (NCs) (where, x varies between 0 and 1) to tune the band gap of hybrid organic-inorganic lead perovskite NCs from 2.38 to 2.94 eV by varying the ratio of ethylammonium (EA) and methylammonium (MA) cations. The tuning of band gap is confirmed by electronic structure calculations within density functional theory, which explains the increase in the band gap upon going toward larger "A" site cations in APbBr3 NCs. The photoluminescence quantum yield (PLQY) of these NCs lies between 5% to 85% and the average lifetime falls in the range 1.4 to 215 ns. A mixture of MA cations and its higher analog EA cations provide a versatile tool to tune the structural as well as optoelectronic properties of perovskite NCs.

  14. Force-gradient-induced mechanical dissipation of quartz tuning fork force sensors used in atomic force microscopy

    Energy Technology Data Exchange (ETDEWEB)

    Castellanos-Gomez, A. [Departamento de Fisica de la Materia Condensada (C-III), Universidad Autonoma de Madrid, Campus de Cantoblanco, 28049 Madrid (Spain); Agrait, N. [Departamento de Fisica de la Materia Condensada (C-III), Universidad Autonoma de Madrid, Campus de Cantoblanco, 28049 Madrid (Spain); Instituto Universitario de Ciencia de Materiales ' Nicolas Cabrera' , Universidad Autonoma de Madrid, Campus de Cantoblanco, 28049 Madrid (Spain); Instituto Madrileno de Estudios Avanzados en Nanociencia, IMDEA-Nanociencia, 28049 Madrid (Spain); Rubio-Bollinger, G., E-mail: gabino.rubio@uam.es [Departamento de Fisica de la Materia Condensada (C-III), Universidad Autonoma de Madrid, Campus de Cantoblanco, 28049 Madrid (Spain); Instituto Universitario de Ciencia de Materiales ' Nicolas Cabrera' , Universidad Autonoma de Madrid, Campus de Cantoblanco, 28049 Madrid (Spain)

    2011-02-15

    We have studied the dynamics of quartz tuning fork resonators used in atomic force microscopy taking into account the mechanical energy dissipation through the attachment of the tuning fork base. We find that the tuning fork resonator quality factor changes even in the case of a purely elastic sensor-sample interaction. This is due to the effective mechanical imbalance of the tuning fork prongs induced by the sensor-sample force gradient, which in turn has an impact on dissipation through the attachment of the resonator base. This effect may yield a measured dissipation signal that can be different from the one exclusively related to the dissipation between the sensor and the sample. We also find that there is a second-order term in addition to the linear relationship between the sensor-sample force gradient and the resonance frequency shift of the tuning fork that is significant even for force gradients usually present in atomic force microscopy, which are in the range of tens of N/m. -- Research Highlights: {yields} Dynamics of miniature tuning fork force sensors: a mechanical model. {yields} Non-linear relationship between resonance frequency shift and applied force gradient. {yields} An apparent mechanical dissipation channel opens even for purely conservative tip-sample interactions. {yields} qPlus tuning forks configuration has lower Q factor but straightforward dynamics.

  15. Large static tuning of narrow-beam terahertz plasmonic lasers operating at 78K

    Science.gov (United States)

    Wu, Chongzhao; Jin, Yuan; Reno, John L.; Kumar, Sushil

    2017-02-01

    A new tuning mechanism is demonstrated for single-mode metal-clad plasmonic lasers, in which the refractive-index of the laser's surrounding medium affects the resonant-cavity mode in the same vein as the refractive-index of gain medium inside the cavity. Reversible, continuous, and mode-hop-free tuning of ˜57 GHz is realized for single-mode narrow-beam terahertz plasmonic quantum-cascade lasers (QCLs), which is demonstrated at a much more practical temperature of 78 K . The tuning is based on post-process deposition/etching of a dielectric (silicon-dioxide) on a QCL chip that has already been soldered and wire-bonded onto a copper mount. This is a considerably larger tuning range compared to previously reported results for terahertz QCLs with directional far-field radiation patterns. The key enabling mechanism for tuning is a recently developed antenna-feedback scheme for plasmonic lasers, which leads to the generation of hybrid surface-plasmon-polaritons propagating outside the cavity of the laser with a large spatial extent. The effect of dielectric deposition on QCL's characteristics is investigated in detail including that on maximum operating temperature, peak output power, and far-field radiation patterns. Single-lobed beam with low divergence (<7° ) is maintained through the tuning range. The antenna-feedback scheme is ideally suited for modulation of plasmonic lasers and their sensing applications due to the sensitive dependence of spectral and radiative properties of the laser on its surrounding medium.

  16. High-Q whispering gallery modes in a polymer microresonator with broad strain tuningHigh-Q whispering gallery modes in a polymer microresonator with broad strain tuning

    Institute of Scientific and Technical Information of China (English)

    ZHOU ZhongHao[1,3; SHU FangJie[1,2; SHEN Zhen[1,3; DONG ChunHua[1,3; GUO GuangCan[1,3

    2015-01-01

    We have reported the high-Q whispering gallery modes (WGMs) in a polydimethylsiloxane (PDMS) optical microresonators with broad tuning range. The PDMS microresonators are fabricated at the center of two collimating fiber tips, which can be controlled by the piezoelectric stage. Through stretching the fiber stem, the tuning range of WGMs are demonstrated more than 50 nm. Further investigations demonstrated that the WGM shift has a high force sensitivity (- 19.7 pm/p.N) of the gravitation when the microcavity is stretched by a weight. The theoretical analysis reveals that the high force sensitivity of polymer microresonator can be used for the weak force or height measurement.

  17. Auto-tuning for NMR probe using LabVIEW

    Science.gov (United States)

    Quen, Carmen; Pham, Stephanie; Bernal, Oscar

    2014-03-01

    Typical manual NMR-tuning method is not suitable for broadband spectra spanning several megahertz linewidths. Among the main problems encountered during manual tuning are pulse-power reproducibility, baselines, and transmission line reflections, to name a few. We present a design of an auto-tuning system using graphic programming language, LabVIEW, to minimize these problems. The program uses a simplified model of the NMR probe conditions near perfect tuning to mimic the tuning process and predict the position of the capacitor shafts needed to achieve the desirable impedance. The tuning capacitors of the probe are controlled by stepper motors through a LabVIEW/computer interface. Our program calculates the effective capacitance needed to tune the probe and provides controlling parameters to advance the motors in the right direction. The impedance reading of a network analyzer can be used to correct the model parameters in real time for feedback control.

  18. Self Tuning Techniques on PLC Background and Control Systems With Self Tuning Methods Design

    Directory of Open Access Journals (Sweden)

    Jiri Koziorek

    2010-01-01

    Full Text Available Advanced Process Control techniques have become standard functions of distributed control systems. Self tuning methods belong to Advanced Process Control (APC techniques. APC techniques contain software packages for advanced control based on mathematical methods. APC tools are designed to increase the process capacity, yield and quality of products. Most of nowadays digital industry regulators and PLCs are provided with some kind of the self tuning constant algorithm. Practical part of the paper deals with design of the control systems which contain self tuning regulator. A control system with PID Self Tuner by Siemens and with visualization in WinCC is designed. There is a description of an implementation of the PID regulator as a function block which can be also used for extension control functions. Control systems for relay and moment self tuner with visualizations in WinCC are also designed.

  19. Mosquitoes on the Wing ``Tune In'' to Acoustic Distortion

    Science.gov (United States)

    Warren, Ben; Russell, Ian

    2011-11-01

    Our current understanding of the mating game for many mosquito species is that males aggregate in noisy mating swarms and listen with their Johnston's organs (JOs) for the deeper flight tones of approaching females, to which they are attracted. As has been demonstrated, at least for the most intensely studied vector species, the mechanical resonance of the flagellum and the frequency range of the female's JO is far below that of the male's flight tones. Therefore, it has been assumed that females do not use hearing to detect the presence of males. Here we reveal that this may not be the case, and that the JOs of female Culex quinquefasciatus are exquisitely tuned to low frequency distortion products in the vibrations of the antenna due to a nonlinear interaction between her own flight tones and those of a nearby male. She can hear male flight tones by virtue of, and not despite, hearing her own flight tones.

  20. Dynamic frequency tuning of electric and magnetic metamaterial response

    Science.gov (United States)

    O'Hara, John F; Averitt, Richard; Padilla, Willie; Chen, Hou-Tong

    2014-09-16

    A geometrically modifiable resonator is comprised of a resonator disposed on a substrate, and a means for geometrically modifying the resonator. The geometrically modifiable resonator can achieve active optical and/or electronic control of the frequency response in metamaterials and/or frequency selective surfaces, potentially with sub-picosecond response times. Additionally, the methods taught here can be applied to discrete geometrically modifiable circuit components such as inductors and capacitors. Principally, controlled conductivity regions, using either reversible photodoping or voltage induced depletion activation, are used to modify the geometries of circuit components, thus allowing frequency tuning of resonators without otherwise affecting the bulk substrate electrical properties. The concept is valid over any frequency range in which metamaterials are designed to operate.

  1. Influence of Varying Tune width on the Robustness of the LHC Tune PLL and its Application for Continuous Chromaticity Measurement

    CERN Document Server

    Boccardi, A; Jones, R; Kasinski, KK; Steinhagen, R

    2007-01-01

    Tune and chromaticity measurement is an integral part of safe and reliable LHC operation. Tight tolerances on the maximum transverse beam excursions allow oscillation amplitudes of less than 30 μm. This leaves only a small margin for transverse beam and momentum excitations required for measuring tune and chromaticity. This contribution discusses a robust tune phase-locked-loop (PLL) operation in the presence of non-linearities and varying chromaticity. The loop design was tested at the SPS, using the LHC PLL prototype system. The system was also used to continuously measure tune width and chromaticity, using resonant transverse excitations of the tune side-slopes.

  2. Harmonic Ratcheting for Ferrite Tuned RF Acceleration of Charged Particles

    Science.gov (United States)

    Cook, Nathan; Brennan, Mike

    2013-04-01

    One of the most persistent difficulties in the design of RF cavities for acceleration of charged particles is the rapid and efficient acceleration of particles over a large range of frequencies. From medical synchrotrons to accelerator driven systems, there is a strong need for fast acceleration of protons and light ions over hundreds of MeV. Conventionally, this is a costly undertaking, requiring specially designed ferrite loaded cavities to be tuned over a large range of frequencies. Ferromagnetic materials allow for the precise adjustment of cavity resonant frequency, but rapid changes in the frequency as well as operation outside material specific frequency ranges result in significant Q-loss to the cavity. This leads to a considerable increase in power required and is thus undesirable for regular operation. We introduce an acceleration scheme known as harmonic ratcheting which can be used to reduce the cavity frequency range needed for accelerating an ion beam in a synchrotron. In particular, this scheme addresses the need for high rep. rate machines for applications such as radiation therapy in which low beam intensity is needed. We demonstrate with simulations the type of ramps achievable using this technique and consider its advantages over h=1 acceleration schemes.

  3. In situ and nonvolatile photoluminescence tuning and nanodomain writing demonstrated by all-solid-state devices based on graphene oxide.

    Science.gov (United States)

    Tsuchiya, Takashi; Tsuruoka, Tohru; Terabe, Kazuya; Aono, Masakazu

    2015-02-24

    In situ and nonvolatile tuning of photoluminescence (PL) has been achieved based on graphene oxide (GO), the PL of which is receiving much attention because of various potential applications of the oxide (e.g., display, lighting, and nano-biosensor). The technique is based on in situ and nonvolatile tuning of the sp(2) domain fraction to the sp(3) domain fraction (sp(2)/sp(3) fraction) in GO through an electrochemical redox reaction achieved by solid electrolyte thin films. The all-solid-state variable PL device was fabricated by GO and proton-conducting mesoporous SiO2 thin films, which showed an extremely low PL background. The device successfully tuned the PL peak wavelength in a very wide range from 393 to 712 nm, covering that for chemically tuned GO, by adjusting the applied DC voltage within several hundred seconds. We also demonstrate the sp(2)/sp(3) fraction tuning using a conductive atomic force microscope. The device achieved not only writing, but also erasing of the sp(2)/sp(3)-fraction-tuned nanodomain (both directions operation). The combination of these techniques is applicable to a wide range of nano-optoelectronic devices including nonvolatile PL memory devices and on-demand rewritable biosensors that can be integrated into nano- and microtips which are transparent, ultrathin, flexible, and inexpensive.

  4. Calibration of piezoelectric positioning actuators using a reference voltage-to-displacement transducer based on quartz tuning forks

    CERN Document Server

    Castellanos-Gomez, Andres; Agraït, Nicolás; Rubio-Bollinger, Gabino; 10.1017/S1431927611012839

    2012-01-01

    We use a piezoelectric quartz tuning fork to calibrate the displacement of ceramic piezoelectric scanners which are widely employed in scanning probe microscopy. We measure the static piezoelectric response of a quartz tuning fork and find it to be highly linear, non-hysteretic and with negligible creep. These performance characteristics, close to those of an ideal transducer, make quartz transducers superior to ceramic piezoelectric actuators. Furthermore, quartz actuators in the form of a tuning fork have the advantage of yielding static displacements comparable to those of local probe microscope scanners. We use the static displacement of a quartz tuning fork as a reference to calibrate the three axis displacement of a ceramic piezoelectric scanner. Although this calibration technique is a non-traceable method, it can be more versatile than using calibration grids because it enables to characterize the linear and non-linear response of a piezoelectric scanner in a broad range of displacements, spanning fro...

  5. iPhone Applications Tune-Up

    CERN Document Server

    Moses, Loyal

    2011-01-01

    Written to be read straight through as well as to be used as a technical reference, each chapter of this book focuses on an individual aspect of application performance and how it relates to the overall development and tune-up process. The reader will be introduced to the fundamentals of iOS performance bottlenecks and how poor application performance can and does affect a user's experience, adoption, and ultimately success This book is for iOS application developers who are interested in resolving application performance bottlenecks in both new and existing Xcode projects. Readers should be f

  6. Planck scale operators, inflation and fine tuning

    CERN Document Server

    Marunovic, Anja

    2016-01-01

    Ultraviolet completion of the standard model plus gravity at and beyond the Planck scale is a daunting problem to which no generally accepted solution exists. Principal obstacles include (a) lack of data at the Planck scale (b) nonrenormalizability of gravity and (c) unitarity problem. Here we make a simple observation that, if one treats all Planck scale operators of equal canonical dimension democratically, one can tame some of the undesirable features of these models. With a reasonable amount of fine tuning one can satisfy slow roll conditions required in viable inflationary models. That remains true even when the number of such operators becomes very large.

  7. A cyclic universe approach to fine tuning

    Energy Technology Data Exchange (ETDEWEB)

    Alexander, Stephon, E-mail: stephon.alexander@dartmouth.edu [Department of Physics and Astronomy, Dartmouth College, Hanover, NH 03755 (United States); Department of Physics, Brown University, Providence, RI 02906 (United States); Cormack, Sam, E-mail: samuel.c.cormack.gr@dartmouth.edu [Department of Physics and Astronomy, Dartmouth College, Hanover, NH 03755 (United States); Gleiser, Marcelo, E-mail: marcelo.gleiser@dartmouth.edu [Department of Physics and Astronomy, Dartmouth College, Hanover, NH 03755 (United States)

    2016-06-10

    We present a closed bouncing universe model where the value of coupling constants is set by the dynamics of a ghost-like dilatonic scalar field. We show that adding a periodic potential for the scalar field leads to a cyclic Friedmann universe where the values of the couplings vary randomly from one cycle to the next. While the shuffling of values for the couplings happens during the bounce, within each cycle their time-dependence remains safely within present observational bounds for physically-motivated values of the model parameters. Our model presents an alternative to solutions of the fine tuning problem based on string landscape scenarios.

  8. Automatic tuning of the reinforcement function

    Energy Technology Data Exchange (ETDEWEB)

    Touzet, C. [Oak Ridge National Lab., TN (United States). Center for Engineering Systems Advanced Research; Santos, J.M. [Univ. de Buenos Aires (Argentina)

    1997-12-31

    The aim of this work is to present a method that helps tuning the reinforcement function parameters in a reinforcement learning approach. Since the proposal of neural based implementations for the reinforcement learning paradigm (which reduced learning time and memory requirements to realistic values) reinforcement functions have become the critical components. Using a general definition for reinforcement functions, the authors solve, in a particular case, the so called exploration versus exploitation dilemma through the careful computation of the RF parameter values. They propose an algorithm to compute, during the exploration part of the learning phase, an estimate for the parameter values. Experiments with the mobile robot Nomad 200 validate their proposals.

  9. Pre - big bang inflation requires fine tuning

    Energy Technology Data Exchange (ETDEWEB)

    Turner, Michael S. [Fermi National Accelerator Laboratory (FNAL), Batavia, IL (United States); Weinberg, Erick J. [Fermi National Accelerator Laboratory (FNAL), Batavia, IL (United States)

    1997-10-01

    The pre-big-bang cosmology inspired by superstring theories has been suggested as an alternative to slow-roll inflation. We analyze, in both the Jordan and Einstein frames, the effect of spatial curvature on this scenario and show that too much curvature --- of either sign --- reduces the duration of the inflationary era to such an extent that the flatness and horizon problems are not solved. Hence, a fine-tuning of initial conditions is required to obtain enough inflation to solve the cosmological problems.

  10. Adaptive tuning of elasto-plastic damper

    DEFF Research Database (Denmark)

    Høgsberg, Jan Riess; Krenk, Steen

    2007-01-01

    Hysteretic dampers are frequency independent, and thereby otentially effective for several structural vibration modes, provided that the inherent amplitude dependence can be controlled. An adaptive tuning procedure is proposed, aiming at elimination of the amplitude dependence by adjusting...... the damper parameter(s) with respect to the magnitude of the damper motion. The procedure is demonstrated in terms of the bilinear elasto-plastic damper model, and optimality corresponds to maximum modal damping. A parametric solution for the damping ratio is obtained by a two-component system reduction...... in controlling the amplitude dependence, resulting in equal damping for the first vibration modes....

  11. Varactor-tuned superconducting filter with constant absolute bandwidth at VHF-band

    Energy Technology Data Exchange (ETDEWEB)

    Li, Bo [Department of Physics, Tsinghua University, Beijing 100084 (China); Cao, Bisong, E-mail: bscao@tsinghua.edu.cn [Department of Physics, Tsinghua University, Beijing 100084 (China); Guo, Xubo; Zhang, Xiaoping [Department of Physics, Tsinghua University, Beijing 100084 (China); Chen, Yidong [Superconductor Technology Co., Ltd, Beijing 100085 (China); Wei, Bin; Jiang, Linan [Department of Physics, Tsinghua University, Beijing 100084 (China)

    2015-09-15

    Highlights: • A four-pole superconducting tunable filter at VHF-band with constant absolute bandwidth is proposed. • The novel resonator consists of a spiral-in-spiral-out (SISO) microstrip line with one end shorted to ground and the other loaded with a varactor diode. • Both combline and interdigital constructions for coupling are introduced, and tuned to meet the constant bandwidth requirements. • The measurements show bandwidth variation is less than 1.3% while tuning from 247.28 to 266.58 MHz, and a high Q{sub u} of 1600–5500 is archived. - Abstract: A four-pole superconducting tunable filter at VHF-band with constant absolute bandwidth is proposed. The resonator consists of a spiral-in-spiral-out (SISO) resonator with one end shorted to ground and the other end loaded with a varactor diode. Both combline and interdigital constructions for coupling are introduced, and tuned to meet the constant bandwidth requirement. The fabricated device has a compact size, a tuning range of 7.3% from 247.28 to 266.58, a 3-dB bandwidth of 2.32 ± 0.03 MHz. The insertion loss ranges from 0.5 to 1.6 dB, yielding a high unloaded Q of 1600–5500. The simulated and measured results show an excellent agreement.

  12. Linking Behavioral and Neurophysiological Indicators of Perceptual Tuning to Language

    Directory of Open Access Journals (Sweden)

    Eswen eFava

    2011-08-01

    Full Text Available Little is known about the neural mechanisms that underlie tuning to the native language(s in early infancy. Here we review language tuning through the lens of language experience and introduce a new manner in which to conceptualize the phenomenon of language tuning: the relative speed of tuning hypothesis. This hypothesis has as its goal a characterization of the unique time course of the tuning process, given the different components (e.g., phonology, prosody, syntax, semantics of one or more languages as they become available to infants. In this review, we first examine the established behavioral findings and integrate more recent neurophysiological data on neonatal development, which together demonstrate evidence of early language tuning given differential language exposure in utero. Next, we examine traditional accounts of sensitive and critical periods to determine how these constructs complement current data on the neural mechanisms underlying language tuning. We then synthesize the extant infant behavioral and imaging literatures on monolingual, bilingual, and sensory deprived tuning experience, thereby scrutinizing the effect of these three different language profiles on the specific timing, progression, and outcomes of language tuning. Finally, we discuss future directions researchers might pursue on this aspect of development, advocating our relative speed of tuning hypothesis as a useful framework for conceptualizing the complex process by which language experience shapes language sensitivity.

  13. Exhaled air analysis using wideband wave number tuning range infrared laser photoacoustic spectroscopy

    Science.gov (United States)

    Kistenev, Yury V.; Borisov, Alexey V.; Kuzmin, Dmitry A.; Penkova, Olga V.; Kostyukova, Nadezhda Y.; Karapuzikov, Alexey A.

    2017-01-01

    The infrared laser photoacoustic spectroscopy (LPAS) and the pattern-recognition-based approach for noninvasive express diagnostics of pulmonary diseases on the basis of absorption spectra analysis of the patient's exhaled air are presented. The study involved lung cancer patients (N=9), patients with chronic obstructive pulmonary disease (N=12), and a control group of healthy, nonsmoking volunteers (N=11). The analysis of the measured absorption spectra was based at first on reduction of the dimension of the feature space using principal component analysis; thereafter, the dichotomous classification was carried out using the support vector machine. The gas chromatography-mass spectrometry method (GC-MS) was used as the reference. The estimated mean value of the sensitivity of exhaled air sample analysis by the LPAS in dichotomous classification was not less than 90% and specificity was not less than 69%; the analogous results of analysis by GC-MS were 68% and 60%, respectively. Also, the approach to differential diagnostics based on the set of SVM classifiers usage is presented.

  14. A novel capacitive detection principle for Coriolis mass flow sensors enabling range/sensitivity tuning

    NARCIS (Netherlands)

    Alveringh, Dennis; Groenesteijn, Jarno; Ma, Kechun; Wiegerink, Remco J.; Lötters, Joost Conrad

    2015-01-01

    We report on a novel capacitive detection principle for Coriolis mass flow sensors which allows for one order of magnitude increased sensitivity. The detection principle consists of two pairs of comb-structures: one pair produces two signals with a phase shift directly dependent on the mass flow,

  15. Telling in-tune from out-of-tune: widespread evidence for implicit absolute intonation.

    Science.gov (United States)

    Van Hedger, Stephen C; Heald, Shannon L M; Huang, Alex; Rutstein, Brooke; Nusbaum, Howard C

    2017-04-01

    Absolute pitch (AP) is the rare ability to name or produce an isolated musical note without the aid of a reference note. One skill thought to be unique to AP possessors is the ability to provide absolute intonation judgments (e.g., classifying an isolated note as "in-tune" or "out-of-tune"). Recent work has suggested that absolute intonation perception among AP possessors is not crystallized in a critical period of development, but is dynamically maintained by the listening environment, in which the vast majority of Western music is tuned to a specific cultural standard. Given that all listeners of Western music are constantly exposed to this specific cultural tuning standard, our experiments address whether absolute intonation perception extends beyond AP possessors. We demonstrate that non-AP listeners are able to accurately judge the intonation of completely isolated notes. Both musicians and nonmusicians showed evidence for absolute intonation recognition when listening to familiar timbres (piano and violin). When testing unfamiliar timbres (triangle and inverted sine waves), only musicians showed weak evidence of absolute intonation recognition (Experiment 2). Overall, these results highlight a previously unknown similarity between AP and non-AP possessors' long-term musical note representations, including evidence of sensitivity to frequency.

  16. Neuromechanical tuning of nonlinear postural control dynamics

    Science.gov (United States)

    Ting, Lena H.; van Antwerp, Keith W.; Scrivens, Jevin E.; McKay, J. Lucas; Welch, Torrence D. J.; Bingham, Jeffrey T.; DeWeerth, Stephen P.

    2009-06-01

    Postural control may be an ideal physiological motor task for elucidating general questions about the organization, diversity, flexibility, and variability of biological motor behaviors using nonlinear dynamical analysis techniques. Rather than presenting "problems" to the nervous system, the redundancy of biological systems and variability in their behaviors may actually be exploited to allow for the flexible achievement of multiple and concurrent task-level goals associated with movement. Such variability may reflect the constant "tuning" of neuromechanical elements and their interactions for movement control. The problem faced by researchers is that there is no one-to-one mapping between the task goal and the coordination of the underlying elements. We review recent and ongoing research in postural control with the goal of identifying common mechanisms underlying variability in postural control, coordination of multiple postural strategies, and transitions between them. We present a delayed-feedback model used to characterize the variability observed in muscle coordination patterns during postural responses to perturbation. We emphasize the significance of delays in physiological postural systems, requiring the modulation and coordination of both the instantaneous, "passive" response to perturbations as well as the delayed, "active" responses to perturbations. The challenge for future research lies in understanding the mechanisms and principles underlying neuromechanical tuning of and transitions between the diversity of postural behaviors. Here we describe some of our recent and ongoing studies aimed at understanding variability in postural control using physical robotic systems, human experiments, dimensional analysis, and computational models that could be enhanced from a nonlinear dynamics approach.

  17. Automatic spike sorting using tuning information.

    Science.gov (United States)

    Ventura, Valérie

    2009-09-01

    Current spike sorting methods focus on clustering neurons' characteristic spike waveforms. The resulting spike-sorted data are typically used to estimate how covariates of interest modulate the firing rates of neurons. However, when these covariates do modulate the firing rates, they provide information about spikes' identities, which thus far have been ignored for the purpose of spike sorting. This letter describes a novel approach to spike sorting, which incorporates both waveform information and tuning information obtained from the modulation of firing rates. Because it efficiently uses all the available information, this spike sorter yields lower spike misclassification rates than traditional automatic spike sorters. This theoretical result is verified empirically on several examples. The proposed method does not require additional assumptions; only its implementation is different. It essentially consists of performing spike sorting and tuning estimation simultaneously rather than sequentially, as is currently done. We used an expectation-maximization maximum likelihood algorithm to implement the new spike sorter. We present the general form of this algorithm and provide a detailed implementable version under the assumptions that neurons are independent and spike according to Poisson processes. Finally, we uncover a systematic flaw of spike sorting based on waveform information only.

  18. Unitary Evolution and Cosmological Fine-Tuning

    CERN Document Server

    Carroll, Sean M

    2010-01-01

    Inflationary cosmology attempts to provide a natural explanation for the flatness and homogeneity of the observable universe. In the context of reversible (unitary) evolution, this goal is difficult to satisfy, as Liouville's theorem implies that no dynamical process can evolve a large number of initial states into a small number of final states. We use the invariant measure on solutions to Einstein's equation to quantify the problems of cosmological fine-tuning. The most natural interpretation of the measure is the flatness problem does not exist; almost all Robertson-Walker cosmologies are spatially flat. The homogeneity of the early universe, however, does represent a substantial fine-tuning; the horizon problem is real. When perturbations are taken into account, inflation only occurs in a negligibly small fraction of cosmological histories, less than $10^{-6.6\\times 10^7}$. We argue that while inflation does not affect the number of initial conditions that evolve into a late universe like our own, it neve...

  19. Comparison of Iterative Feedback Tuning Search Techniques

    Institute of Scientific and Technical Information of China (English)

    Graham E. A.; Xie S. Q.; Gamage P.

    2006-01-01

    Iterative feedback tuning is an attractive method for industry as it is a model free approach using experiments conducted on the plant to tune controller parameters. Classically Gauss-Newton iterative methods are used in IFT to update the controller parameters in the negative gradient direction of a specified design criterion function. Levenburg-Marquardt and Trust-Region strategies offer attractive advantages to Gauss-Newton in many applications, these alternative methods are given and results from simulation presented. A discussion on the differences between line search methods and Trust-Region methods is given showing the Trust-Region search direction is more flexible. Step size selection is often the limiting factor and it is found that with unknown step size values and initial controller parameters the Trust-Region is the best selection, where as if overshoot is a concern Levenburg-Marquardt is a good choice.Gauss-Newton method provides quick convergence and a fast response time however it shows more dependence on the step size.

  20. First tuning of HERWIG/JIMMY to ATLAS data

    CERN Document Server

    The ATLAS collaboration

    2010-01-01

    This note describes the first systematic tuning of the HERWIG generator to ATLAS data, with the JIMMY model for multiple parton interactions. We present a new set of HERWIG/JIMMY tunes for the MRST LO∗, CTEQ6L1 and CTEQ6.6 PDFs, collectively titled "AUET1". The MC09 HERWIG/JIMMY tuning was taken as a starting point for the AUET1 tunes, but important methodological modifications have been made, in particular use of more tuning parameters. In the tuning of the regularisation scale for multiple scattering, an energy-dependence ansatz similar to the one found in the PYTHIA 6 generator has been used. While CDF data has been included in the fits, the weighting is strongly biased towards ATLAS underlying event data, particularly at 7 TeV.

  1. Improving Convergence of Iterative Feedback Tuning using Optimal External Perturbations

    DEFF Research Database (Denmark)

    Huusom, Jakob Kjøbsted; Hjalmarsson, Håkon; Poulsen, Niels Kjølstad

    2008-01-01

    Iterative feedback tuning constitutes an attractive control loop tuning method for processes in the absence of sufficient process insight. It is a purely data driven approach to optimization of the loop performance. The standard formulation ensures an unbiased estimate of the loop performance cost...... function gradient, which is used in a search algorithm. A slow rate of convergence of the tuning method is often experienced when tuning for disturbance rejection. This is due to a poor signal to noise ratio in the process data. A method is proposed for increasing the information content in data...... by introducing an optimal perturbation signal in the tuning algorithm. For minimum variance control design the optimal design of an external perturbation signal is derived in terms of the asymptotic accuracy of the iterative feedback tuning method....

  2. Nonmonotonic Synaptic Excitation and Imbalanced Inhibition Underlying Cortical Intensity Tuning

    OpenAIRE

    Wu, Guangying K.; Li, Pingyang; Tao, Huizhong W.; Zhang, Li I.

    2006-01-01

    Intensity-tuned neurons, characterized by their nonmonotonic response-level function, may play important roles in the encoding of sound intensity-related information. The synaptic mechanisms underlying intensity-tuning remain yet unclear. Here, in vivo whole-cell recordings in rat auditory cortex revealed that intensity-tuned neurons, mostly clustered in a posterior zone, receive imbalanced tone-evoked excitatory and inhibitory synaptic inputs. Excitatory inputs exhibit nonmonotonic intensity...

  3. Application research of tune measurement system in Hefei light source

    CERN Document Server

    Sun Bao Gen; Xu Hong Liang; Lu Ping; Wang Jun; Gao Yun Feng; Wang Li; LiuJinYing

    2002-01-01

    The author introduces the measurement and research of some beam parameters using tune measurement system for Hefei Light Source (HLS), which include the betatron tune, beta function, natural chromaticity, corrected chromaticity, and central frequency. Additionally, it also describes the measurement of the influence of DC clearing electrodes on the betatron tune shift and gives some measurement results. The measurement results are compared with the theoretical values and they are in good agreement

  4. Small Commercial Building Re-tuning: A Primer

    Energy Technology Data Exchange (ETDEWEB)

    Cort, Katherine A.; Hostick, Donna J.; Underhill, Ronald M.; Fernandez, Nicholas; Katipamula, Srinivas

    2013-09-30

    To help building owners and managers address issues related to energy-efficient operation of small buildings, DOE has developed a Small Building Re-tuning training curriculum. This "primer" provides additional background information to understand some of the concepts presented in the Small Building Re-tuning training. The intent is that those who are less familiar with the buidling energy concepts will review this material before taking the building re-tuning training class.

  5. Tuning Coler Magnetic Current Apparatus with Magneto-Acoustic Resonance

    Science.gov (United States)

    Ludwig, Thorsten

    An attempt was made to tune the Coler magnetic current apparatus with the magneto acoustic resonance of the magnetic rods. Measurements with a replica of the famous Coler "Magnetstromapparat" were conducted. In order to tune the acoustic, magnetic and electric resonance circuits of the Coler device the magneto-acoustic resonance was measured with a frequency scan through a function generator and a lock-in amplifier. The frequency generator was powering a driving coil, while the lock-in was connected to a pickup coil. Both coils were placed on a magnetic rod. Resonances were observed up to the 17th harmonic. The quality Q of the observed resonances was 270. To study the magneto-acoustic resonance in the time domain a pair of Permendur rods were employed. The magneto-acoustic resonances of the Permendur rods were observed with an oscilloscope. Spectra of the magneto acoustic resonance were measured for the Permendur rods and for a Coler replica magnet in the frequency range from 25 kHz to 380 kHz. The next step was to bring the resonances of the Permendur rods close together so that they overlap. The 10thharmonic was chosen because it was close to the 180 kHz that Hans Coler related to ferromagnetism. Further more magneto-acoustic coupling between the Permendur rods was studied. Finally the question was explored if Hans Coler converted vacuum fluctuations via magnetic and acoustic resonance into electricity. There is a strong connection between magnetism and quantum field zero point energy (ZPE). An outlook is given on next steps in the experiments to unveil the working mechanism of the Coler magnetic current apparatus.

  6. Iterative feedback tuning of uncertain state space systems

    Directory of Open Access Journals (Sweden)

    J. K. Huusom

    2010-09-01

    Full Text Available Iterative Feedback Tuning is a purely data driven tuning algorithm for optimizing control parameters based on closed loop data. The algorithm is designed to produce an unbiased estimate of the performance cost function gradient for iteratively improving the control parameters to achieve optimal loop performance. This tuning method has been developed for systems based on a transfer function representation. This paper presents a state feedback control system with a state observer and its transfer function equivalent in terms of input output dynamics. It is shown how the parameters in the closed loop state space system can be tuned by Iterative Feedback Tuning utilizing this equivalent representation. A simulation example illustrates that the tuning converges to the known analytical solution for the feedback control gain and to the Kalman gain in the state observer. In case of parametric uncertainty, different choices of tuning parameters are investigated. It is shown that the data driven tuning method produces optimal performance for convex problems when it is the model parameter estimates in the observer that are tuned.

  7. Driving the Power of AIX Performance Tuning on IBM Power

    CERN Document Server

    Milberg, Ken

    2009-01-01

    A concise reference for IT professionals, this book goes beyond the rules and contains the best practices and strategies for solid tuning methodology. Tips based on years of experience from an AIX tuning master show specific steps for monitoring and tuning CPU, virtual memory, disk I/O, and network components. Also offering techniques for tuning Oracle and Linux structures that run on an IBM power system-as well as for the new AIX 6.1-this manual discusses what tools are available, how to best use them to collect historical data, and when to analyze trends and results. The only comprehensive,

  8. Neural tuning characteristics of auditory primary afferents in the chicken embryo

    Science.gov (United States)

    Jones, S. M.; Jones, T. A.

    1995-01-01

    Primary afferent activity was recorded from the cochlear ganglion in chicken embryos (Gallus domesticus) at 19 days of incubation (E19). The ganglion was accessed via the recessus scala tympani and impaled with glass micropipettes. Frequency tuning curves were obtained using a computerized threshold tracking procedure. Tuning curves were evaluated to determine characteristics frequencies (CFs), CF thresholds, slopes of low and high frequency flanks, and tip sharpness (Q10dB). The majority of tuning curves exhibited the typical 'V' shape described for older birds and, on average, appeared relatively mature based on mean values for CF thresholds (59.6 +/- 20.3 dBSPL) and tip sharpness (Q10dB = 5.2 +/- 3). The mean slopes of low (61.9 +/- 37 dB/octave) and high (64.6 +/- 33 dB/octave) frequency flanks although comparable were somewhat less than those reported for 21-day-old chickens. Approximately 14% of the tuning curves displayed an unusual 'saw-tooth' pattern. CFs ranged from 188 to 1623 Hz. The highest CF was well below those reported for post-hatch birds. In addition, a broader range of Q10dB values (1.2 to 16.9) may related to a greater variability in embryonic tuning curves. Overall, these data suggest that an impressive functional maturity exists in the embryo at E19. The most significant sign of immaturity was the limited expression of high frequencies. It is argued that the limited high CF in part may be due to the developing middle ear transfer function and/or to a functionally immature cochlear base.

  9. Wireless tuning fork gyroscope for biomedical applications

    Science.gov (United States)

    Abraham, Jose K.; Varadan, Vijay K.; Whitchurch, Ashwin K.; Sarukesi, K.

    2003-07-01

    This paper presents the development of a Bluetooth enabled wireless tuning fork gyroscope for the biomedical applications, including gait phase detection system, human motion analysis and physical therapy. This gyroscope is capable of measuring rotation rates between -90 and 90 and it can read the rotation information using a computer. Currently, the information from a gyroscope can trigger automobile airbag deployment during rollover, improve the accuracy and reliability of GPS navigation systems and stabilize moving platforms such as automobiles, airplanes, robots, antennas, and industrial equipment. Adding wireless capability to the existing gyroscope could help to expand its applications in many areas particularly in biomedical applications, where a continuous patient monitoring is quite difficult. This wireless system provides information on several aspects of activities of patients for real-time monitoring in hospitals.

  10. Fine tuning of cytosolic Ca 2+ oscillations

    Science.gov (United States)

    Dupont, Geneviève; Combettes, Laurent

    2016-01-01

    Ca 2+ oscillations, a widespread mode of cell signaling, were reported in non-excitable cells for the first time more than 25 years ago. Their fundamental mechanism, based on the periodic Ca 2+ exchange between the endoplasmic reticulum and the cytoplasm, has been well characterized. However, how the kinetics of cytosolic Ca 2+ changes are related to the extent of a physiological response remains poorly understood. Here, we review data suggesting that the downstream targets of Ca 2+ are controlled not only by the frequency of Ca 2+ oscillations but also by the detailed characteristics of the oscillations, such as their duration, shape, or baseline level. Involvement of non-endoplasmic reticulum Ca 2+ stores, mainly mitochondria and the extracellular medium, participates in this fine tuning of Ca 2+ oscillations. The main characteristics of the Ca 2+ exchange fluxes with these compartments are also reviewed. PMID:27630768

  11. Chemical and biological sensing using tuning forks

    Science.gov (United States)

    Tao, Nongjian; Boussaad, Salah

    2012-07-10

    A device for sensing a chemical analyte is disclosed. The device is comprised of a vibrating structure having first and second surfaces and having an associated resonant frequency and a wire coupled between the first and second surfaces of the vibrating structure, wherein the analyte interacts with the wire and causes a change in the resonant frequency of the vibrating structure. The vibrating structure can include a tuning fork. The vibrating structure can be comprised of quartz. The wire can be comprised of polymer. A plurality of vibrating structures are arranged in an array to increase confidence by promoting a redundancy of measurement or to detect a plurality of chemical analytes. A method of making a device for sensing a chemical analyte is also disclosed.

  12. Tuning particle focusing in inertial microfluidic devices

    Science.gov (United States)

    Hood, Kaitlyn; Kahkeshani, Soroush; di Carlo, Dino; Roper, Marcus

    2014-11-01

    Particles in microfluidic devices at finite Reynolds number are subject to two forces: (i) inertial focusing and (ii) particle-particle interactions. Although microfluidic chips exploit these forces to manipulate particles for particle/cell sorting and high throughput flow cytometry, the forces are not understood well enough to allow rational design of devices that can tune and attenuate particle focusing. We present a mathematical model addressing both inertial focusing and particle interactions, and we apply our model to various channel geometries to determine the balance of forces. In addition, we present experimental data that illustrate the accuracy of our model. We will address the following questions: Why do high aspect ratio channels favor two equilibrium positions? Why do particle chains form?

  13. Interphase tuning for stronger and tougher composites.

    Science.gov (United States)

    Livanov, Konstantin; Yang, Lin; Nissenbaum, Asaf; Wagner, H Daniel

    2016-05-27

    The development of composite materials that are simultaneously strong and tough is one of the most active topics of current material science. Observations of biological structural materials show that adequate introduction of reinforcements and interfaces, or interphases, at different scales usually improves toughness, without reduction in strength. The prospect of interphase properties tuning may lead to further increases in material toughness. Here we use evaporation-driven self-assembly (EDSA) to deposit a thin network of multi-wall carbon nanotubes on ceramic surfaces, thereby generating an interphase reinforcing layer in a multiscale laminated ceramic composite. Both strength and toughness are improved by up to 90%, while keeping the overall volume fraction of nanotubes in a composite below 0.012%, making it a most effective toughening and reinforcement technique.

  14. Interleaved Parton Showers and Tuning Prospects

    CERN Document Server

    Corke, Richard

    2010-01-01

    General-purpose Monte Carlo event generators have become important tools in particle physics, allowing the simulation of exclusive hadronic final states. In this article we examine the Pythia 8 generator, in particular focusing on its parton-shower algorithms. Some relevant new additions to the code are introduced, that should allow for a better description of data. We also implement and compare with 2 to 3 real-emission QCD matrix elements, to check how well the shower algorithm fills the phase space away from the soft and collinear regions. A tuning of the generator to Tevatron data is performed for two PDF sets and the impact of first new LHC data is examined.

  15. Which fine-tuning arguments are fine?

    CERN Document Server

    Grinbaum, Alexei

    2009-01-01

    The argument from naturalness is widely employed in contemporary quantum field theory. Essentially a formalized aesthetic criterion, it received a meaning in the debate on the Higgs mechanism, which goes beyond aesthetics. We follow the history of technical definitions of fine tuning at the scale of electroweak symmetry breaking. It is argued that they give rise to a special interpretation of probability, which we call Gedankenfrequency. By extension of its original meaning, the argument from naturalness is used to compare different models beyond the Standard Model. We show that in this case naturalness cannot be defined objectively. Rather, it functions as socio-historical heuristics in particle physics and it contributes to the advent of a probabilistic version of Popper's falsificationism.

  16. Tuning the Catalytic Activity of Subcellular Nanoreactors.

    Science.gov (United States)

    Jakobson, Christopher M; Chen, Yiqun; Slininger, Marilyn F; Valdivia, Elias; Kim, Edward Y; Tullman-Ercek, Danielle

    2016-07-31

    Bacterial microcompartments are naturally occurring subcellular organelles of bacteria and serve as a promising scaffold for the organization of heterologous biosynthetic pathways. A critical element in the design of custom biosynthetic organelles is quantitative control over the loading of heterologous enzymes to the interior of the organelles. We demonstrate that the loading of heterologous proteins to the 1,2-propanediol utilization microcompartment of Salmonella enterica can be controlled using two strategies: by modulating the transcriptional activation of the microcompartment container and by coordinating the expression of the microcompartment container and the heterologous cargo. These strategies allow general control over the loading of heterologous proteins localized by two different N-terminal targeting peptides and represent an important step toward tuning the catalytic activity of bacterial microcompartments for increased biosynthetic productivity. Copyright © 2016. Published by Elsevier Ltd.

  17. Performance Optimization and Auto-Tuning

    Energy Technology Data Exchange (ETDEWEB)

    Howison, Mark

    2012-10-01

    In the broader computational research community, one subject of recent research is the problem of adapting algorithms to make effective use of multi- and many-core processors. Effective use of these architectures, which have complex memory hierarchies with many layers of cache, typically involves a careful examination of how an algorithm moves data through the memory hierarchy. Unfortunately, there is often a non-obvious relationship between algorithmic parameters like blocking strategies, and their impact on memory utilization, and, in turn, the relationship with runtime performance. Auto-tuning is an empirical method used to discover optimal values for tunable algorithmic parameters under such circumstances. The challenge is compounded by the fact that the settings that produce the best performance for a given problem and a given platform may not be the best for a different problem on the same platform, or the same problem on a different platform. The high performance visualization research community has begun to explore and adapt the principles of auto-tuning for the purpose of optimizing codes on modern multi- and many-core processors. This report focuses on how performance optimization studies reveal a dramatic variation in performance for two fundamental visualization algorithms: one based on a stencil operation having structured, uniform memory access, and the other is ray casting volume rendering, which uses unstructured memory access patterns. The two case studies highlighted in this report show the extra effort required to optimize such codes by adjusting the tunable algorithmic parameters can return substantial gains in performance. Additionally, these case studies also explore the potential impact of and the interaction between algorithmic optimizations and tunable algorithmic parameters, along with the potential performance gains resulting from leveraging architecture-specific features.

  18. A Performance Tuning Methodology with Compiler Support

    Directory of Open Access Journals (Sweden)

    Oscar Hernandez

    2008-01-01

    Full Text Available We have developed an environment, based upon robust, existing, open source software, for tuning applications written using MPI, OpenMP or both. The goal of this effort, which integrates the OpenUH compiler and several popular performance tools, is to increase user productivity by providing an automated, scalable performance measurement and optimization system. In this paper we describe our environment, show how these complementary tools can work together, and illustrate the synergies possible by exploiting their individual strengths and combined interactions. We also present a methodology for performance tuning that is enabled by this environment. One of the benefits of using compiler technology in this context is that it can direct the performance measurements to capture events at different levels of granularity and help assess their importance, which we have shown to significantly reduce the measurement overheads. The compiler can also help when attempting to understand the performance results: it can supply information on how a code was translated and whether optimizations were applied. Our methodology combines two performance views of the application to find bottlenecks. The first is a high level view that focuses on OpenMP/MPI performance problems such as synchronization cost and load imbalances; the second is a low level view that focuses on hardware counter analysis with derived metrics that assess the efficiency of the code. Our experiments have shown that our approach can significantly reduce overheads for both profiling and tracing to acceptable levels and limit the number of times the application needs to be run with selected hardware counters. In this paper, we demonstrate the workings of this methodology by illustrating its use with selected NAS Parallel Benchmarks and a cloud resolving code.

  19. Dynamic Tuning of Transmission Wavelength of MEMS-Based Ge Waveguides on a Si Beam

    Directory of Open Access Journals (Sweden)

    Masashi Hirase

    2016-03-01

    Full Text Available Three-dimensional structures of microelectro-mechanical systems (MEMS-based Ge waveguide on a Si beam were fabricated for dynamic tuning of the fundamental absorption edge of Ge by external stressing. The application of various amounts of external forces up to 1 GPa onto the Si beam shows clear red-shifts in the absorption edge of Ge waveguides on the Si beam by ~40 nm. This shift was reproduced by the deformation potential theory, considering that mode of propagation in the Ge waveguide. The wavelength tuning range obtained makes it possible to cover the whole C-band of optical communication, indicating it to be a promising approach to electro-absorption Ge modulators to get them to work with a broader wavelength range than previously reported.

  20. Ultrafast broadband tuning of resonant optical nanostructures using phase change materials

    CERN Document Server

    Rudé, Miquel; Cetin, Arif E; Miller, Timothy A; Carrilero, Albert; Wall, Simon; de Abajo, F Javier García; Altug, Hatice; Pruneri, Valerio

    2015-01-01

    The phenomenon of extraordinary optical transmission {EOT} through arrays of nanoholes patterned in a metallic film has emerged as a promising tool for a wide range of applications, including photovoltaics, nonlinear optics, and sensing. Designs and methods enabling the dynamic tuning of the optical resonances of these structures are essential to build efficient optical devices, including modulators, switches, filters, and biosensors. However, the efficient combination of EOT and dynamic tuning remains a challenge, mainly because of the lack of materials that can induce modulation over a broad spectral range at high speeds. Here, we demonstrate tuneable resonance wavelength shifts as large as 385 nm - an order of magnitude higher than previously reported - through the combination of phase change materials {PCMs}, which exhibit dramatic variations in optical properties upon transitions between amorphous and crystalline phases, with properly designed subwavelength nanohole metallic arrays. We further find throu...

  1. Genetic Algorithm Based PID Controller Tuning Approach for Continuous Stirred Tank Reactor

    Directory of Open Access Journals (Sweden)

    A. Jayachitra

    2014-01-01

    Full Text Available Genetic algorithm (GA based PID (proportional integral derivative controller has been proposed for tuning optimized PID parameters in a continuous stirred tank reactor (CSTR process using a weighted combination of objective functions, namely, integral square error (ISE, integral absolute error (IAE, and integrated time absolute error (ITAE. Optimization of PID controller parameters is the key goal in chemical and biochemical industries. PID controllers have narrowed down the operating range of processes with dynamic nonlinearity. In our proposed work, globally optimized PID parameters tend to operate the CSTR process in its entire operating range to overcome the limitations of the linear PID controller. The simulation study reveals that the GA based PID controller tuned with fixed PID parameters provides satisfactory performance in terms of set point tracking and disturbance rejection.

  2. Enhancement and electric charge-assisted tuning of nonlinear light generation in bipolar plasmonics.

    Science.gov (United States)

    Ding, Wei; Zhou, Liangcheng; Chou, Stephen Y

    2014-05-14

    We propose and experimentally demonstrate a new plasmonic nonlinear light generation (NLG) structure, termed plasmonic-enhanced, charge-assisted second-harmonic generator (p-CASH), that not only achieves high second-harmonic generation (SHG) enhancement (76-fold), large SHG tunability by bias (8%/V), wide tuning range (280%), 7.8 × 10(-9) conversion efficiency, and high stability but also exhibits a SHG tuning, that is bipolar rather than unipolar, not due to the third-order nonlinear polarization term, hence fundamentally different from the classic electric field induced SHG-tuning (EFISH). We propose a new SHG tuning mechanism: the second-order nonlinear polarization term enhanced by plasmonic effects, changed by charge injection and negative oxygen vacancies movement, and is nearly 3 orders of magnitude larger than EFISH. p-CASH is a bipolar parallel-plate capacitor with thin layers of plasmonic nanostructures, a TiOx (semiconductor and nonlinear) and a SiO2 (insulator) sandwiched between two electrodes. Fabrication of p-CASH used nanoimprint on 4″ wafer and is scalable to wallpaper-sized areas. The new structure, new properties, and new understanding should open up various new designs and applications of NLG in various fields.

  3. Piezoelectric tuning of narrowband perfect plasmonic absorbers via an optomechanic cavity.

    Science.gov (United States)

    Yang, Ao; Yang, Kecheng; Yu, Hongbin; Tan, Xiaochao; Li, Junyu; Zhou, Lun; Liu, Huan; Song, Haisheng; Tang, Jiang; Liu, Feng; Zhu, Alexander Yutong; Guo, Qiushi; Yi, Fei

    2016-06-15

    Optical antennas enable the control of light-matter interaction on the nanometer scale. Efficient on-chip electrical switching of plasmonic resonances is a crucial step toward the integration of optical antennas into practical optoelectronic circuits. We propose and numerically investigate the on-chip low-voltage linear electrical tuning of a narrowband optical antenna perfect absorber via a piezoelectric optomechanic cavity. Near unity absorption is realized by an array of gold nanostrip antennas separated from a membrane-based deformable backreflector by a small gap. A narrow linewidth of 33 nm at 2.58 μm is realized through the coupling between the plasmonic mode and photonic mode in the cavity-enhanced antenna structure. An aluminum nitride piezoelectric layer enabled efficient actuation of the backreflector and therefore changed the gap size, allowing for the tuning of the spectral absorption. The peak wavelength can be shifted linearly by 250 nm with 10 V of tuning voltage, and the tuning range is not limited by the pull-in effect. The polarization dependence of the nanostrip antenna coupled with the optomechanic cavity allows the use of our device as a voltage tunable polarization control device.

  4. Geometrical tuning art for entirely subwavelength grating waveguide based integrated photonics circuits.

    Science.gov (United States)

    Wang, Zheng; Xu, Xiaochuan; Fan, Donglei; Wang, Yaguo; Subbaraman, Harish; Chen, Ray T

    2016-05-05

    Subwavelength grating (SWG) waveguide is an intriguing alternative to conventional optical waveguides due to the extra degree of freedom it offers in tuning a few important waveguide properties, such as dispersion and refractive index. Devices based on SWG waveguides have demonstrated impressive performances compared to conventional waveguides. However, the high loss of SWG waveguide bends jeopardizes their applications in integrated photonic circuits. In this work, we propose a geometrical tuning art, which realizes a pre-distorted refractive index profile in SWG waveguide bends. The pre-distorted refractive index profile can effectively reduce the mode mismatch and radiation loss simultaneously, thus significantly reduce the bend loss. This geometry tuning art has been numerically optimized and experimentally demonstrated in present study. Through such tuning, the average insertion loss of a 5 μm SWG waveguide bend is reduced drastically from 5.43 dB to 1.10 dB per 90° bend for quasi-TE polarization. In the future, the proposed scheme will be utilized to enhance performance of a wide range of SWG waveguide based photonics devices.

  5. Design of an iterative auto-tuning algorithm for a fuzzy PID controller

    Science.gov (United States)

    Saeed, Bakhtiar I.; Mehrdadi, B.

    2012-05-01

    Since the first application of fuzzy logic in the field of control engineering, it has been extensively employed in controlling a wide range of applications. The human knowledge on controlling complex and non-linear processes can be incorporated into a controller in the form of linguistic terms. However, with the lack of analytical design study it is becoming more difficult to auto-tune controller parameters. Fuzzy logic controller has several parameters that can be adjusted, such as: membership functions, rule-base and scaling gains. Furthermore, it is not always easy to find the relation between the type of membership functions or rule-base and the controller performance. This study proposes a new systematic auto-tuning algorithm to fine tune fuzzy logic controller gains. A fuzzy PID controller is proposed and applied to several second order systems. The relationship between the closed-loop response and the controller parameters is analysed to devise an auto-tuning method. The results show that the proposed method is highly effective and produces zero overshoot with enhanced transient response. In addition, the robustness of the controller is investigated in the case of parameter changes and the results show a satisfactory performance.

  6. PID tuning rules for SOPDT systems: review and some new results.

    Science.gov (United States)

    Panda, Rames C; Yu, Cheng-Ching; Huang, Hsiao-Ping

    2004-04-01

    PID controllers are widely used in industries and so many tuning rules have been proposed over the past 50 years that users are often lost in the jungle of tuning formulas. Moreover, unlike PI control, different control laws and structures of implementation further complicate the use of the PID controller. In this work, five different tuning rules are taken for study to control second-order plus dead time systems with wide ranges of damping coefficients and dead time to time constant ratios (D/tau). Four of them are based on IMC design with different types of approximations on dead time and the other on desired closed-loop specifications (i.e., specified forward transfer function). The method of handling dead time in the IMC type of design is important especially for systems with large D/tau ratios. A systematic approach was followed to evaluate the performance of controllers. The regions of applicability of suitable tuning rules are highlighted and recommendations are also given. It turns out that IMC designed with the Maclaurin series expansion type PID is a better choice for both set point and load changes for systems with D/tau greater than 1. For systems with D/tau less than 1, the desired closed-loop specification approach is favored.

  7. Emission wavelength tuning of fluorescence by fine structural control of optical metamaterials with Fano resonance

    Science.gov (United States)

    Moritake, Y.; Kanamori, Y.; Hane, K.

    2016-09-01

    We demonstrated fine emission wavelength tuning of quantum dot (QD) fluorescence by fine structural control of optical metamaterials with Fano resonance. An asymmetric-double-bar (ADB), which was composed of only two bars with slightly different bar lengths, was used to obtain Fano resonance in the optical region. By changing the short bar length of ADB structures with high dimensional accuracy in the order of 10 nm, resonant wavelengths of Fano resonance were controlled from 1296 to 1416 nm. Fluorescence of QDs embedded in a polymer layer on ADB metamaterials were modified due to coupling to Fano resonance and fine tuning from 1350 to 1376 nm was observed. Wavelength tuning of modified fluorescence was reproduced by analysis using absorption peaks of Fano resonance. Tuning range of modified fluorescence became narrow, which was interpreted by a simple Gaussian model and resulted from comparable FWHM in QD fluorescence and Fano resonant peaks. The results will help the design and fabrication of metamaterial devices with fluorophores such as light sources and biomarkers.

  8. Emission wavelength tuning of fluorescence by fine structural control of optical metamaterials with Fano resonance.

    Science.gov (United States)

    Moritake, Y; Kanamori, Y; Hane, K

    2016-09-13

    We demonstrated fine emission wavelength tuning of quantum dot (QD) fluorescence by fine structural control of optical metamaterials with Fano resonance. An asymmetric-double-bar (ADB), which was composed of only two bars with slightly different bar lengths, was used to obtain Fano resonance in the optical region. By changing the short bar length of ADB structures with high dimensional accuracy in the order of 10 nm, resonant wavelengths of Fano resonance were controlled from 1296 to 1416 nm. Fluorescence of QDs embedded in a polymer layer on ADB metamaterials were modified due to coupling to Fano resonance and fine tuning from 1350 to 1376 nm was observed. Wavelength tuning of modified fluorescence was reproduced by analysis using absorption peaks of Fano resonance. Tuning range of modified fluorescence became narrow, which was interpreted by a simple Gaussian model and resulted from comparable FWHM in QD fluorescence and Fano resonant peaks. The results will help the design and fabrication of metamaterial devices with fluorophores such as light sources and biomarkers.

  9. Electro-Thermal Tuning in a Negative Dielectric Cholesteric Liquid Crystal Material

    Energy Technology Data Exchange (ETDEWEB)

    Natarajan,L.; Wofford, J.; Tondiglia, V.; Sutherland, R.; Koerner, H.; Vaia, R.; Bunning, T.

    2008-01-01

    The thermal and electrical tunability of a cholesteric liquid crystal containing a negative dielectric anisotropy liquid crystal in a planar alignment was studied. The physical, optical, and electro-optical characteristics of mixtures containing different ratios of chiral dopant S811 and the negative dielectric anisotropy liquid crystal ZLI-2806 were examined. A smectic A phase was seen at room temperature for S811 loadings >20 wt%. Below 20%, a room temperature cholesteric phase was observed. Upon heating mixtures with composition S811 >20%, the selective reflection notch of the cholesteric phase appeared and blueshifted with temperature. Thermal tuning from 2300?to?500?nm was observed over the temperature range of 23-55? C. Polarized optical microscopy, differential scanning calorimetry, and x-ray studies were utilized to confirm the temperature-dependent phase behavior. Tuning of ? 50?nm by the application of a direct current electric field was also observed with no onset of electrohydrodynamic instabilities for voltages up to {approx} 300 V. Bandwidth broadening but not tuning was obtained with the application of alternating current fields. Electrical tuning is likely due to pitch contraction brought about through the annealing of defects.

  10. Noncontact atomic force microscopy in liquid environment with quartz tuning fork and carbon nanotube probe

    DEFF Research Database (Denmark)

    Kageshima, M.; Jensenius, Henriette; Dienwiebel, M.

    2002-01-01

    A force sensor for noncontact atomic force microscopy in liquid environment was developed by combining a multiwalled carbon nanotube (MWNT) probe with a quartz tuning fork. Solvation shells of octamethylcyclotetrasiloxane surface were detected both in the frequency shift and dissipation. Due...... to the high aspect ratio of the CNT probe, the long-range background force was barely detectable in the solvation region. (C) 2002 Elsevier Science B.V. All rights reserved....

  11. Formant tuning strategies in professional male opera singers.

    Science.gov (United States)

    Sundberg, Johan; Lã, Filipa M B; Gill, Brian P

    2013-05-01

    The term "formant tuning" is generally used for the case that one of the lowest formant frequencies coincides with the frequency of a source spectrum partial. Some authors claim that such coincidence is favorable and belongs to the goals of classical opera voice training, whereas other authors have found evidence for advising against it. This investigation analyzes the relationships between formant frequencies and partials in professional singers, who sang scales on the vowels /a/, /u/, /i/, and /ae/ in a pitch range including the passaggio, that is, the fundamental frequency range of approximately 300-400Hz, applying either of the two singing strategies that are typically used (1) in classical and (2) in nonclassical singing, respectively. Formant frequencies of each note in the scales were measured by inverse-filtering the acoustic signal. In the classical style, the first formant tended to be lower than in the nonclassical style. Neither the first nor the second formant tended to change systematically between scale tones, such that on some scale tones either or both formants was just below, just above, or right on a spectrum partial. In many cases, singers produced similar spectrum characteristics of the top tones of the scales with different first and second formant frequencies. Regardless of whether the first formant was slightly lower, slightly higher, or right on a partial, the properties of the voice source did not seem to be affected.

  12. Riboswitch function: Flipping the switch or tuning the dimmer?

    Energy Technology Data Exchange (ETDEWEB)

    Baird, Nathan J.; Kulshina, Nadia; Ferré D' Amaré, Adrian R. (FHCRC)

    2010-10-08

    Riboswitches are structured mRNA elements involved in gene regulation that respond to the intracellular concentration of specific small molecules. Binding of their cognate ligand is thought to elicit a global conformational change of the riboswitch, in addition to modulating the fine structure of the binding site. X-ray crystallography has produced detailed descriptions of the three-dimensional structures of the ligand-bound conformations of several riboswitches. We have employed small-angle X-ray scattering (SAXS) to generate low-resolution reconstructions of the ligand-free states of the ligand-binding domains of riboswitches that respond to thiamine pyrophosphate (TPP), and cyclic diguanylate (c-di-GMP), a bacterial second messenger. Comparison of the SAXS reconstructions with the crystal structures of these two riboswitches demonstrates that the RNAs undergo dramatic ligand-induced global conformational changes. However, this is not an universal feature of riboswitches. SAXS analysis of the solution behavior of several other riboswitch ligand-binding domains demonstrates a broad spectrum of conformational switching behaviors, ranging from the unambiguous switching of the TPP and c-di-GMP riboswitches to complete lack of switching for the flavin mononucleotide (FMN) riboswitch. Moreover, the switching behavior varies between examples of the same riboswitch from different organisms. The range of observed behaviors suggests that in response to the evolutionary need for precise genetic regulation, riboswitches may be tuned to function more as dimmers or rheostats than binary on/off switches.

  13. The general RF tuning for IH-DTL linear accelerators

    Energy Technology Data Exchange (ETDEWEB)

    Lu, Y.R. [Key State Laboratory of Nuclear Physics and Technology, Peking University (China)], E-mail: yrlu@pku.edu.cn; Ratzinger, U. [Institute of Applied Physics, Frankfurt University (Germany); Schlitt, B. [Gesellschaft fuer Schwerionenforschung, mbH, Darmstadt (Germany); Tiede, R. [Institute of Applied Physics, Frankfurt University (Germany)

    2007-11-21

    The RF tuning is the most important research for achieving the resonant frequency and the flatness of electric field distributions along the axis of RF accelerating structures. The six different tuning concepts and that impacts on the longitudinal field distributions have been discussed in detail combining the RF tuning process of a 1:2 modeled 20.85 MV compact IH-DTL cavity, which was designed to accelerate proton, helium, oxygen or C{sup 4+} from 400 keV/u to 7 MeV/u and used as the linear injector of 430 MeV/u synchrotron [Y.R. Lu, S. Minaev, U. Ratzinger, B. Schlitt, R.Tiede, The Compact 20MV IH-DTL for the Heidelberg Therapy Facility, in: Proceedings of the LINAC Conference, Luebeck, Germany, 2004 ; Y.R. Lu, Frankfurt University Dissertation, 2005. ] in Heidelberg Heavy Ion Cancer Therapy (HICAT). Some of tuning concepts are also suitable and effective for the tuning of RFQ and/or other RF accelerating structures. Finally good field flatness in IH-DTL cavity has been realized successfully. The experience got from the model cavity tuning benefits real power cavity tuning, which is only needed to be tuned by the plungers. The cavity had a beam commissioning successfully for the initial beam acceleration at the end of 2006.

  14. Field Flatness Tuning for PEFP 100 MeV DTL

    Energy Technology Data Exchange (ETDEWEB)

    Kim, Han-Sung; Kwon, Hyeok-Jung; Seol, Kyung-Tae; Kim, Dae-Il; Cho, Yong-Sub [Korea Atomic Energy Research Institute, Daejeon (Korea, Republic of)

    2008-05-15

    A conventional 100 MeV drift tube linac is under development for Proton Engineering Frontier Project. Currently the proton linac up to 20 MeV, which consists of injector, 3 MeV RFQ and 20 MeV DTL is completed. To accelerate the proton beam up to 100 MeV additional 7 DTL tanks are required. The DTL should be tuned after fabrication and alignment of the drift tube inside the tank to meet the requirements from the beam dynamics. Tuning process includes the resonant frequency tuning, field flatness tuning and tilt sensitivity tuning. The tuning goal for the field flatness tuning is less than {+-}2% in field uniformity throughout the DTL tank with less than {+-}% standard deviation. A non-uniform field profile caused by the machining errors and alignment errors can be made uniform through the slug tuner adjustment. This procedure requires the field profile measurements and several iterations between the field profile measurements and adjustment. The methods and the results of the DTL field flatness tuning will be reported in this presentation.

  15. Local tuning of photonic crystal cavities using chalcogenide glasses

    Science.gov (United States)

    Faraon, Andrei; Englund, Dirk; Bulla, Douglas; Luther-Davies, Barry; Eggleton, Benjamin J.; Stoltz, Nick; Petroff, Pierre; Vučković, Jelena

    2008-01-01

    We demonstrate a method to locally change the refractive index in planar optical devices by photodarkening of a thin chalcogenide glass layer deposited on top of the device. The method is used to tune the resonance of GaAs-based photonic crystal cavities by up to 3nm at 940nm. The method has broad applications for postproduction tuning of photonic devices.

  16. More self-tuning solutions with $H_{MNPQ}$

    CERN Document Server

    Kim, J E; Kim, Jihn E.; Lee, Hyun Min

    2002-01-01

    We find more self-tuning solutions by introducing a general form for Lagrangian of a 3-index antisymmetric tensor field $A_{MNP}$ in the RS II model. In particular, for the logarithmic Lagrangian, $\\propto\\log(-H^2)$, we obtained a closed form weak self-tuning solution.

  17. PID motion control tuning rules in a damping injection framework

    NARCIS (Netherlands)

    Tadele, Tadele Shiferaw; Vries, de Theo; Stramigioli, Stefano

    2013-01-01

    This paper presents a general design approach for a performance based tuning of a damping injection framework impedance controller by using insights from PID motion control tuning rules. The damping injection framework impedance controller is suitable for human friendly robots as it enhances safety

  18. Automatic tuning of quality factors for VHF CMOS filters

    NARCIS (Netherlands)

    Nauta, Bram; Seevinck, Evert

    1990-01-01

    A VHF transconductance-C filter technique with automatic tuning of the quality factors and the cutoff frequency, based on a voltage controlled oscillator (VCO), is presented. The Q-tuning circuit is very simple and contains no signal carrying nodes, resulting in a well-controlled Q up to very high f

  19. Further ATLAS tunes of PYTHIA6 and Pythia 8

    CERN Document Server

    The ATLAS collaboration

    2011-01-01

    We present the latest developments of the ATLAS MC generator tuning project for the Pythia family of event generators, including the C++ Pythia 8 code. The PYTHIA 6 tunes presented here complete the ``AUET2B'' set by addition of parton shower and multi-parton interaction model tunings with three next-to-leading order (NLO) PDFs in addition to the leading-order and MC-adapted PDFs previously presented. This note also presents systematic variation ``eigentunes'' for the parton shower configurations in the AMBT2B/AUET2B tune series. The Pythia 8 MPI tunes in this note have been constructed for six different PDFs, making use of a new $x$-dependent hadronic matter distribution model. MPI eigentunes are constructed for the PDFs intended for use in ATLAS bulk MC production.

  20. New ATLAS event generator tunes to 2010 data

    CERN Document Server

    The ATLAS collaboration

    2011-01-01

    This note describes the Monte Carlo event generator tunings for the Pythia 6 and Herwig/Jimmy generators in the ATLAS MC11 simulation production. New tunes have been produced for these generators, making maximal use of available published data from ATLAS and from the Tevatron and LEP experiments. Particular emphasis has been placed on improvement of the description of e+ e− event shape and jet rate data, and on description of hadron collider event shape observables in Pythia, as well as the established procedure of tuning the multiple parton interactions of both models to describe underlying event and minimum bias data. The tuning of Pythia is provided at this time for the MRST LO∗∗ PDF, while the purely MPI tune of Herwig/Jimmy is performed for ten different PDFs.

  1. Tuning of a neuro-fuzzy controller by genetic algorithm.

    Science.gov (United States)

    Seng, T L; Bin Khalid, M; Yusof, R

    1999-01-01

    Due to their powerful optimization property, genetic algorithms (GAs) are currently being investigated for the development of adaptive or self-tuning fuzzy logic control systems. This paper presents a neuro-fuzzy logic controller (NFLC) where all of its parameters can be tuned simultaneously by GA. The structure of the controller is based on the radial basis function neural network (RBF) with Gaussian membership functions. The NFLC tuned by GA can somewhat eliminate laborious design steps such as manual tuning of the membership functions and selection of the fuzzy rules. The GA implementation incorporates dynamic crossover and mutation probabilistic rates for faster convergence. A flexible position coding strategy of the NFLC parameters is also implemented to obtain near optimal solutions. The performance of the proposed controller is compared with a conventional fuzzy controller and a PID controller tuned by GA. Simulation results show that the proposed controller offers encouraging advantages and has better performance.

  2. Evaluation of Controller Tuning Methods Applied to Distillation Column Control

    DEFF Research Database (Denmark)

    Nielsen, Kim; W. Andersen, Henrik; Kümmel, Professor Mogens

    1998-01-01

    of this is to examine whether ZN and BLT design yield satisfactory control of distillation columns. Further, PI controllers are tuned according to a proposed multivariable frequency domain method. A major conclusion is that the ZN tuned controllers yield undesired overshoot and oscillation and poor stability robustness...... properties. BLT tuning removes the overshoot and oscillation, however, at the expense of a more sluggish response. We conclude that if a simple control design is to be used, the BLT method should be referred compared to the ZN method. The frequency domain design approach presented yields a more proper trade...... off between oscillation, response time and stability robustness. However, this method is more complicated to use than the ZN and BLT methods. Moreover, it is shown that properly tuned diagonal PI controllers can provide performance and robustness properties which equal well tuned PI controllers...

  3. Otoacoustic Estimates of Cochlear Tuning: Testing Predictions in Macaque

    Science.gov (United States)

    Shera, Christopher A.; Bergevin, Christopher; Kalluri, Radha; Laughlin, Myles Mc; Michelet, Pascal; van der Heijden, Marcel; Joris, Philip X.

    2013-01-01

    Otoacoustic estimates of cochlear frequency selectivity suggest substantially sharper tuning in humans. However, the logic and methodology underlying these estimates remain untested by direct measurements in primates. We report measurements of frequency tuning in macaque monkeys, Old-World primates phylogenetically closer to humans than the small laboratory animals often taken as models of human hearing (e.g., cats, guinea pigs, and chinchillas). We find that measurements of tuning obtained directly from individual nerve fibers and indirectly using otoacoustic emissions both indicate that peripheral frequency selectivity in macaques is significantly sharper than in small laboratory animals, matching that inferred for humans at high frequencies. Our results validate the use of otoacoustic emissions for noninvasive measurement of cochlear tuning and corroborate the finding of sharper tuning in humans. PMID:24701000

  4. Compensating tune spread induced by space charge in bunched beams

    Energy Technology Data Exchange (ETDEWEB)

    Litvinenko, V.; Wang, G.

    2015-05-03

    The effects of space charge play a significant role in modern-day accelerators, frequently constraining the beam parameters attainable in an accelerator or in an accelerator chain. They also can limit the luminosity of hadron colliders operating either at low energies or with sub-TeV high-brightness hadron beams. The latter is applied for strongly cooled proton and ion beams in eRHIC – the proposed future electron-ion collider at Brookhaven National Laboratory. Using an appropriate electron beam would compensate both the tune shift and the tune spread in the hadron beam in a coasting beam. But these methods cannot compensate space charge tune spread in a bunched hadron beam. In this paper we propose and evaluate a novel idea of using a co-propagating electron bunch with mismatched longitudinal velocity to compensate the space charge induced tune-shift and tune spread.

  5. Compensating tune spread induced by space charge in bunched beams

    Energy Technology Data Exchange (ETDEWEB)

    Litvinenko, V.; Wang, G.

    2015-05-03

    The effects of space charge play a significant role in modern-day accelerators, frequently constraining the beam parameters attainable in an accelerator or in an accelerator chain. They also can limit the luminosity of hadron colliders operating either at low energies or with sub-TeV high-brightness hadron beams. The latter is applied for strongly cooled proton and ion beams in eRHIC – the proposed future electron-ion collider at Brookhaven National Laboratory. Using an appropriate electron beam would compensate both the tune shift and the tune spread in the hadron beam in a coasting beam. But these methods cannot compensate space charge tune spread in a bunched hadron beam. In this paper we propose and evaluate a novel idea of using a co-propagating electron bunch with mismatched longitudinal velocity to compensate the space charge induced tune-shift and tune spread.

  6. iPod and iTunes for dummies

    CERN Document Server

    Bove, Tony

    2013-01-01

    Get going with your iPod & iTunes and this perennial bestseller - now in full-color! iPod & iTunes For Dummies is the ultimate beginner's guide for getting started with your iPod and Apple's iTunes service. Now in its tenth edition, this helpful guide has been completely overhauled and boasts a full-color format for the first time ever. Veteran For Dummies author Tony Bove introduces you to the different iPod models, explains how to power up your iPod, and shows you how to set up iTunes. You'll learn to personalize your device, add music tracks from a CD to your iTune

  7. Iterative Feedback Tuning in district heating systems; Iterative Feedback Tuning i vaermeproduktionsanlaeggningar

    Energy Technology Data Exchange (ETDEWEB)

    Raaberg, Martin; Velut, Stephane; Bari, Siavosh Amanat

    2010-10-15

    The project goal is to evaluate and describe how Iterative Feedback Tuning (IFT) can be used to tune controllers in the typical control loops in heat- and power plants. There are only a few practical studies carried out for IFT and they are not really relevant for power and heat processes. It is the practical problems in implementing the IFT and the result of trimming that is the focus of this project. The project will start with theoretical studies of the IFT-method, then realization and simple simulations in scilab. The IFT equations are then implemented in Freelance 2000, an ABB control system, for practical tests on a SISO- and a MIMO-process. By performing reproducible experiments on the process and analyze the results IFT can adjust the controller parameters to minimize a cost function that represents the control goal. The project selected for SISO experiments a pressure controller in an oil transportation system. By controlling the valve position of a control valve for the reversal to the supply tank, the pressure in the oil transport system is regulated. A disturbance in oil pressure can be achieved by changing the position of a valve that lets oil through to the day tank. The selected MIMO-process is a pre-heater in a degassing process. In this process, a valve on the secondary side is utilized to control the flow in the secondary system. A valve on the primary side is utilized to control the district heating water flow through the heat exchanger to control the temperature on the secondary side. An increased secondary flow increases the heat demand and thus requiring an increase in primary flow to maintain the secondary side outlet temperature. This is the cross-coupling responsible for why it is an advantage to consider the process as multi-variable. Using the IFT method, the two original PID-controllers and a feed-forward controller is tuned simultaneously. IFT-method was difficult to implement but worked well in both simulations and in real processes

  8. Simultaneous gains tuning in boiler/turbine PID-based controller clusters using iterative feedback tuning methodology.

    Science.gov (United States)

    Zhang, Shu; Taft, Cyrus W; Bentsman, Joseph; Hussey, Aaron; Petrus, Bryan

    2012-09-01

    Tuning a complex multi-loop PID based control system requires considerable experience. In today's power industry the number of available qualified tuners is dwindling and there is a great need for better tuning tools to maintain and improve the performance of complex multivariable processes. Multi-loop PID tuning is the procedure for the online tuning of a cluster of PID controllers operating in a closed loop with a multivariable process. This paper presents the first application of the simultaneous tuning technique to the multi-input-multi-output (MIMO) PID based nonlinear controller in the power plant control context, with the closed-loop system consisting of a MIMO nonlinear boiler/turbine model and a nonlinear cluster of six PID-type controllers. Although simplified, the dynamics and cross-coupling of the process and the PID cluster are similar to those used in a real power plant. The particular technique selected, iterative feedback tuning (IFT), utilizes the linearized version of the PID cluster for signal conditioning, but the data collection and tuning is carried out on the full nonlinear closed-loop system. Based on the figure of merit for the control system performance, the IFT is shown to deliver performance favorably comparable to that attained through the empirical tuning carried out by an experienced control engineer.

  9. Design and Testing of a Dynamically-Tuned Magnetostrictive Spring with Electrically-Controlled Stiffness

    Science.gov (United States)

    Scheidler, Justin; Asnani, Vivake M.; Dapino, Marcelo J.

    2015-01-01

    This paper details the development of an electrically-controlled, variable-stiffness spring based on magnetostrictive materials. The device, termed a magnetostrictive Varispring, can be applied as a semi-active vibration isolator or switched stiffness vibration controller for reducing transmitted vibrations. The Varispring is designed using 1D linear models that consider the coupled electrical response, mechanically-induced magnetic diffusion, and the effect of internal mass on dynamic stiffness. Modeling results illustrate that a Terfenol-D-based Varispring has a rise time almost an order of magnitude smaller and a magnetic diffusion cut-off frequency over two orders of magnitude greater than a Galfenol-based Varispring. The results motivate the use of laminated Terfenol-D rods for a greater stiffness tuning range and increased bandwidth. The behavior of a prototype Varispring is examined under vibratory excitation up to 6 MPa and 25 Hz using a dynamic load frame. For this prototype, stiffness is indirectly varied by controlling the excitation current. Preliminary measurements of continuous stiffness tuning via sinusoidal currents up to 1 kHz are presented. The measurements demonstrate that the Young's modulus of the Terfenol-D rod inside the Varispring can be continuously varied by up to 21.9 GPa. The observed stiffness tuning range is relatively constant up to 500 Hz, but significantly decreases thereafter. The stiffness tuning range can be greatly increased by improving the current and force control such that a more consistent current can be applied and the Varispring can be accurately tested at a more optimal bias stress.

  10. Structurally tuned iridescent surfaces inspired by nature

    Energy Technology Data Exchange (ETDEWEB)

    Deparis, Olivier; Rassart, Marie; Vandenbem, Cedric; Welch, Victoria; Vigneron, Jean Pol [Laboratoire de Physique du Solide, University of Namur, 61 rue de Bruxelles, 5000 Namur (Belgium); Lucas, Stephane [Laboratoire d' Analyses par Reactions Nucleaires, University of Namur, 61 rue de Bruxelles, 5000 Namur (Belgium)], E-mail: olivier.deparis@fundp.ac.be

    2008-01-15

    Iridescent surfaces exhibit vivid colours which change with the angle of incidence or viewing due to optical wave interference in the multilayer structure present at the wavelength scale underneath the surface. In nature, one can find examples of iridescent Coleoptera for which the hue changes either greatly or slightly with the angle. Because these species typically make these structures from a single biological material (usually chitin) and air or water as the low refractive index component, they have evolved by adjusting the layer thicknesses in order to display quite different iridescent aspects. Taking inspiration from this proven strategy, we have designed and fabricated periodic TiO{sub 2}/SiO{sub 2} multilayer films in order to demonstrate the concept of structurally tuned iridescent surfaces. Titanium or silicon oxide layers were deposited on a glass substrate using dc reactive or RF magnetron sputtering techniques, respectively. Two structures were designed for which the period and the TiO{sub 2}/SiO{sub 2} layer thickness ratio were varied in such a way that the films displayed radically different iridescent aspects: a reddish-to-greenish changing hue and a stable bluish hue. The fabricated samples were characterized through specular reflectance/transmittance measurements. Modelling of transmittance spectra using standard multilayer film theory confirmed the high quality of the twelve-period Bragg reflectors. The chromaticity coordinates, which were calculated from measured reflectance spectra taken at different angles, were in accordance with theoretical predictions.

  11. Social Cognition in Williams Syndrome: Face Tuning.

    Science.gov (United States)

    Pavlova, Marina A; Heiz, Julie; Sokolov, Alexander N; Barisnikov, Koviljka

    2016-01-01

    Many neurological, neurodevelopmental, neuropsychiatric, and psychosomatic disorders are characterized by impairments in visual social cognition, body language reading, and facial assessment of a social counterpart. Yet a wealth of research indicates that individuals with Williams syndrome exhibit remarkable concern for social stimuli and face fascination. Here individuals with Williams syndrome were presented with a set of Face-n-Food images composed of food ingredients and in different degree resembling a face (slightly bordering on the Giuseppe Arcimboldo style). The primary advantage of these images is that single components do not explicitly trigger face-specific processing, whereas in face images commonly used for investigating face perception (such as photographs or depictions), the mere occurrence of typical cues already implicates face presence. In a spontaneous recognition task, participants were shown a set of images in a predetermined order from the least to most resembling a face. Strikingly, individuals with Williams syndrome exhibited profound deficits in recognition of the Face-n-Food images as a face: they did not report seeing a face on the images, which typically developing controls effortlessly recognized as a face, and gave overall fewer face responses. This suggests atypical face tuning in Williams syndrome. The outcome is discussed in the light of a general pattern of social cognition in Williams syndrome and brain mechanisms underpinning face processing.

  12. Social cognition in Williams syndrome: face tuning

    Directory of Open Access Journals (Sweden)

    Marina A Pavlova

    2016-08-01

    Full Text Available Many neurological, neurodevelopmental, neuropsychiatric and psychosomatic disorders are characterized by impairments in visual social cognition, body language reading, and facial assessment of a social counterpart. Yet a wealth of research indicates that individuals with Williams syndrome exhibit remarkable concern for social stimuli and face fascination. Here individuals with Williams syndrome were presented with a set of Face-n-Food images composed of food ingredients and in different degree resembling a face (slightly bordering on the Giuseppe Arcimboldo style. The primary advantage of these images is that single components do not explicitly trigger face-specific processing, whereas in face images commonly used for investigating face perception (such as photographs or depictions, the mere occurrence of typical cues already implicates face presence. In a spontaneous recognition task, participants were shown a set of images in a predetermined order from the least to most resembling a face. Strikingly, individuals with Williams syndrome exhibited profound deficits in recognition of the Face-n-Food images as a face: they did not report seeing a face on the images, which typically developing controls effortlessly recognized as a face, and gave overall fewer face responses. This suggests atypical face tuning in Williams syndrome. The outcome is discussed in the light of a general pattern of social cognition in Williams syndrome and brain mechanisms underpinning face processing.

  13. Rotationally relaxed, grating tuned laser oscillations in optically pumped C/sub 2/D/sub 2/

    Energy Technology Data Exchange (ETDEWEB)

    Fischer, T.A.; Wittig, C.

    1982-07-15

    Rotationally relaxed, grating tuned laser oscillations are obtained in the frequency range 500--562 cm/sup -1/ via the optical pumping of C/sub 2/D/sub 2//He mixtures with a transverse, electric, atmospheric (TEA) CO/sub 2/ laser. Strong Q-branch oscillations at 530.8 cm/sup -1/ are also reported.

  14. Review of linear collider beam-beam interaction

    Energy Technology Data Exchange (ETDEWEB)

    Chen, P.

    1989-01-01

    Three major effects from the interaction of e/sup +/e/sup /minus// beams---disruption, beamstrahlung, and electron-positron pair creation---are reviewed. For the disruption effects we discuss the luminosity enhancement factor, the maximum and rms disruption angles, and the ''kink instability''. All the results are obtained from computer simulations. Scaling laws for the numerical results and theoretical explanations of the computer acquired phenomena are offered wherever possible. For the beamstrahlung effects we concentrate only on the final electron energy spectrum resulting from multiple photon radiation process, and the deflection angle associated with low energy particles. For the effects from electron-positron pair creation, both coherent and incoherent processes of beamstrahlung pair creation are discussed. In addition to the estimation on total number of such pairs, we also look into the energy spectrum and the deflection angle. 17 refs., 23 figs., 1 tab.

  15. On Bandwidth Characteristics of Tuning Fork Micro-Gyroscope with Mechanically Coupled Sense Mode

    Directory of Open Access Journals (Sweden)

    Yunfang Ni

    2014-07-01

    Full Text Available The bandwidth characteristics of a tuning fork micro-gyroscope with mechanically coupled sense mode were investigated in this paper to provide some references for mechanical bandwidth design. The concept of sense mode mechanical coupling is introduced first. Theoretical frequency response analyses were then carried out on the mechanical part of the gyroscope. Equations representing the relationships between the differential output signal and the frequency of the input angular rate were deduced in full frequency range and further simplified in low frequency range. Based on these equations, bandwidth characteristics under ideal and non-ideal conditions are discussed. Analytical results show that under ideal conditions, the bandwidth characteristics of a tuning fork micro-gyroscope are similar to those of a single mass micro-gyroscope, but under non-ideal conditions, especially when sense mass and/or stiffness are asymmetric, the bandwidth characteristics would be quite different because the in-phase mode would participate in the anti-phase vibration response. Experimental verifications were carried out on two micro-gyroscope prototypes designed in our laboratory. The deduced equations and analytical results can be used in guiding the mechanical bandwidth design of tuning fork micro-gyroscopes with mechanically coupled sense mode.

  16. On bandwidth characteristics of tuning fork micro-gyroscope with mechanically coupled sense mode.

    Science.gov (United States)

    Ni, Yunfang; Li, Hongsheng; Huang, Libin; Ding, Xukai; Wang, Haipeng

    2014-01-01

    The bandwidth characteristics of a tuning fork micro-gyroscope with mechanically coupled sense mode were investigated in this paper to provide some references for mechanical bandwidth design. The concept of sense mode mechanical coupling is introduced first. Theoretical frequency response analyses were then carried out on the mechanical part of the gyroscope. Equations representing the relationships between the differential output signal and the frequency of the input angular rate were deduced in full frequency range and further simplified in low frequency range. Based on these equations, bandwidth characteristics under ideal and non-ideal conditions are discussed. Analytical results show that under ideal conditions, the bandwidth characteristics of a tuning fork micro-gyroscope are similar to those of a single mass micro-gyroscope, but under non-ideal conditions, especially when sense mass and/or stiffness are asymmetric, the bandwidth characteristics would be quite different because the in-phase mode would participate in the anti-phase vibration response. Experimental verifications were carried out on two micro-gyroscope prototypes designed in our laboratory. The deduced equations and analytical results can be used in guiding the mechanical bandwidth design of tuning fork micro-gyroscopes with mechanically coupled sense mode.

  17. Vibroacoustic modeling of an acoustic resonator tuned by dielectric elastomer membrane with voltage control

    Science.gov (United States)

    Yu, Xiang; Lu, Zhenbo; Cheng, Li; Cui, Fangsen

    2017-01-01

    This paper investigates the acoustic properties of a duct resonator tuned by an electro-active membrane. The resonator takes the form of a side-branch cavity which is attached to a rigid duct and covered by a pre-stretched Dielectric Elastomer (DE) in the neck area. A three-dimensional, analytical model based on the sub-structuring approach is developed to characterize the complex structure-acoustic coupling between the DE membrane and its surrounding acoustic media. We show that such resonator provides sound attenuation in the medium frequency range mainly by means of sound reflection, as a result of the membrane vibration. The prediction accuracy of the proposed model is validated against experimental test. The pre-stretched DE membrane with fixed edges responds to applied voltage change with a varying inner stress and, by the same token, its natural frequency and vibrational response can be tuned to suit particular frequencies of interest. The peaks in the transmission loss (TL) curves can be shifted towards lower frequencies when the voltage applied to the DE membrane is increased. Through simulations on the effect of increasing the voltage level, the TL shifting mechanism and its possible tuning range are analyzed. This paves the way for applying such resonator device for adaptive-passive noise control.

  18. An efficient automated parameter tuning framework for spiking neural networks.

    Science.gov (United States)

    Carlson, Kristofor D; Nageswaran, Jayram Moorkanikara; Dutt, Nikil; Krichmar, Jeffrey L

    2014-01-01

    As the desire for biologically realistic spiking neural networks (SNNs) increases, tuning the enormous number of open parameters in these models becomes a difficult challenge. SNNs have been used to successfully model complex neural circuits that explore various neural phenomena such as neural plasticity, vision systems, auditory systems, neural oscillations, and many other important topics of neural function. Additionally, SNNs are particularly well-adapted to run on neuromorphic hardware that will support biological brain-scale architectures. Although the inclusion of realistic plasticity equations, neural dynamics, and recurrent topologies has increased the descriptive power of SNNs, it has also made the task of tuning these biologically realistic SNNs difficult. To meet this challenge, we present an automated parameter tuning framework capable of tuning SNNs quickly and efficiently using evolutionary algorithms (EA) and inexpensive, readily accessible graphics processing units (GPUs). A sample SNN with 4104 neurons was tuned to give V1 simple cell-like tuning curve responses and produce self-organizing receptive fields (SORFs) when presented with a random sequence of counterphase sinusoidal grating stimuli. A performance analysis comparing the GPU-accelerated implementation to a single-threaded central processing unit (CPU) implementation was carried out and showed a speedup of 65× of the GPU implementation over the CPU implementation, or 0.35 h per generation for GPU vs. 23.5 h per generation for CPU. Additionally, the parameter value solutions found in the tuned SNN were studied and found to be stable and repeatable. The automated parameter tuning framework presented here will be of use to both the computational neuroscience and neuromorphic engineering communities, making the process of constructing and tuning large-scale SNNs much quicker and easier.

  19. Tuning polymer glass formation with additives and ions

    Science.gov (United States)

    Simmons, David

    2015-03-01

    A polymer's glass transition and associated dynamic and mechanical properties are among the most important factors determining its performance in engineering applications. For this reason, decades of research have aimed to establish methods of tuning polymers' glass formation behavior. Here I describe molecular simulations providing new insight into two approaches to altering a polymer's glass formation behavior: introduction of small-molecule diluents; and introduction of charged moieties to form an ionomer. In the first case, we explore how diluent molecular properties control modifications to the host polymer's glass transition and mechanical response. Results indicate that diluents can induce a rich array of effects, necessitating development of an expanded classification beyond the usual plasticizer/antiplasticizer dichotomy. In the second case, simulations indicate that ionomer glass formation is indistinguishable from that in polymer nanocomposites, in contrast to the longstanding assumption that covalent grafting of chains to ionic aggregates in these systems leads to a qualitatively distinct effect. Taken together, these results provide new guidance towards the rational understanding and control of polymer glass-formation in a range of materials. In collaboration with Jayachandra Hari Mangalara and Dihui Ruan, The University of Akron. This material is based in part on work supported by the W.M. Keck Foundation.

  20. Molecular Spectrum Capture by Tuning the Chemical Potential of Graphene

    Directory of Open Access Journals (Sweden)

    Yue Cheng

    2016-05-01

    Full Text Available Due to its adjustable electronic properties and effective excitation of surface plasmons in the infrared and terahertz frequency range, research on graphene has attracted a great deal of attention. Here, we demonstrate that plasmon modes in graphene-coated dielectric nanowire (GNW waveguides can be excited by a monolayer graphene ribbon. What is more the transverse resonant frequency spectrum of the GNW can be flexibly tuned by adjusting the chemical potential of graphene, and amplitude of the resonance peak varies linearly with the imaginary part of the analyte permittivity. As a consequence, the GNW works as a probe for capturing the molecular spectrum. Broadband sensing of toluene, ethanol and sulfurous anhydride thin layers is demonstrated by calculating the changes in spectral intensity of the propagating mode and the results show that the intensity spectra correspond exactly to the infrared spectra of these molecules. This may open an effective avenue to design sensors for detecting nanometric-size molecules in the terahertz and infrared regimes.

  1. Electronically Tuned Local Oscillators for the NOEMA Interferometer

    Science.gov (United States)

    Mattiocco, Francois; Garnier, Olivier; Maier, Doris; Navarrini, Alessandro; Serres, Patrice

    2016-03-01

    We present an overview of the electronically tuned local oscillator (LO) system developed at the Institut de RadioAstronomie millimetrique (IRAM) for the superconductor-insulator-superconductor (SIS) receivers of the NOrthern Extended Millimeter Array interferometer (NOEMA). We modified the frequency bands and extended the bandwidths of the LO designs developed by the National Radio Astronomy Observatory (NRAO) for the Atacama Large Millimeter Array (ALMA) project to cover the four NOEMA LO frequency ranges 82-108.3 GHz (Band 1), 138.6-171.3 GHz (Band 2), 207.7-264.4 GHz (Band 3), and 283-365 GHz (Band 4). The NOEMA LO system employs commercially available MMICs and GaAs millimeter MMICs from NRAO which are micro-assembled into active multiplied chain (AMC) and power amplifier (PA) modules. We discuss the problem of the LO spurious harmonics and of the LO signal directly multiplied by the SIS mixers that add extra noise and lead to detections of unwanted spectral lines from higher order sidebands. A waveguide filter in the LO path is used to reduce the higher order harmonics level of the LO at the output of the final frequency multiplier, thus mitigating the undesired effects and improving the system noise temperature.

  2. Sticky Tunes: How Do People React to Involuntary Musical Imagery?

    Science.gov (United States)

    Williamson, Victoria J.; Liikkanen, Lassi A.; Jakubowski, Kelly; Stewart, Lauren

    2014-01-01

    The vast majority of people experience involuntary musical imagery (INMI) or ‘earworms’; perceptions of spontaneous, repetitive musical sound in the absence of an external source. The majority of INMI episodes are not bothersome, while some cause disruption ranging from distraction to anxiety and distress. To date, little is known about how the majority of people react to INMI, in particular whether evaluation of the experience impacts on chosen response behaviours or if attempts at controlling INMI are successful or not. The present study classified 1046 reports of how people react to INMI episodes. Two laboratories in Finland and the UK conducted an identical qualitative analysis protocol on reports of INMI reactions and derived visual descriptive models of the outcomes using grounded theory techniques. Combined analysis carried out across the two studies confirmed that many INMI episodes were considered neutral or pleasant, with passive acceptance and enjoyment being among the most popular response behaviours. A significant number of people, however, reported on attempts to cope with unwanted INMI. The most popular and effective behaviours in response to INMI were seeking out the tune in question, and musical or verbal distraction. The outcomes of this study contribute to our understanding of the aetiology of INMI, in particular within the framework of memory theory, and present testable hypotheses for future research on successful INMI coping strategies. PMID:24497938

  3. Overwrite fabrication and tuning of long period gratings.

    Science.gov (United States)

    Partridge, Matthew; James, Stephen W; Barrington, James; Tatam, Ralph P

    2016-10-03

    The central wavelengths of the resonance bands are critical aspect of the performance of long period gratings (LPGs) as sensors, particularly for devices designed to operate near the phase matching turning point (PMTP), where the sensitivity to measurements can vary rapidly. Generally, LPGs are characterized by their period, but the amplitude of the amplitude of the index modulation is also an important factor in determining the wavelengths of the resonance bands. Variations in fabrication between LPG sensors can increase or decrease the sensitivity of the LPG to strain, temperature or surrounding refractive index. Here, the technique of overwritten UV laser fabrication is demonstrated. It is shown that, on repeated overwriting, the resonance bands of an LPG exhibit significant wavelength shift, which can be monitored and which can be used to tune the resonance bands to the desired wavelengths. This technique is applied to periods in the range 100 to 200 µm, showing the cycle-to-cycle evolution of the resonance bands near the PMTPs of a number of cladding modes. The use of online monitoring is shown to reduce the resonance band sensor-to-sensor central wavelength variation from 10 nm to 3 nm.

  4. Tuning the Photon Statistics of a Strongly Coupled Nanophotonic System

    CERN Document Server

    Dory, Constantin; Müller, Kai; Lagoudakis, Konstantinos G; Sarmiento, Tomas; Rundquist, Armand; Zhang, Jingyuan L; Kelaita, Yousif; Sapra, Neil V; Vučković, Jelena

    2016-01-01

    We investigate the dynamics of single- and multi-photon emission from detuned strongly coupled systems based on the quantum-dot-photonic-crystal resonator platform. Transmitting light through such systems can generate a range of non-classical states of light with tunable photon counting statistics due to the nonlinear ladder of hybridized light-matter states. By controlling the detuning between emitter and resonator, the transmission can be tuned to strongly enhance either single- or two-photon emission processes. Despite the strongly-dissipative nature of these systems, we find that by utilizing a self-homodyne interference technique combined with frequency-filtering we are able to find a strong two-photon component of the emission in the multi-photon regime. In order to explain our correlation measurements, we propose rate equation models that capture the dominant processes of emission both in the single- and multi-photon regimes. These models are then supported by quantum-optical simulations that fully cap...

  5. Sticky tunes: how do people react to involuntary musical imagery?

    Directory of Open Access Journals (Sweden)

    Victoria J Williamson

    Full Text Available The vast majority of people experience involuntary musical imagery (INMI or 'earworms'; perceptions of spontaneous, repetitive musical sound in the absence of an external source. The majority of INMI episodes are not bothersome, while some cause disruption ranging from distraction to anxiety and distress. To date, little is known about how the majority of people react to INMI, in particular whether evaluation of the experience impacts on chosen response behaviours or if attempts at controlling INMI are successful or not. The present study classified 1046 reports of how people react to INMI episodes. Two laboratories in Finland and the UK conducted an identical qualitative analysis protocol on reports of INMI reactions and derived visual descriptive models of the outcomes using grounded theory techniques. Combined analysis carried out across the two studies confirmed that many INMI episodes were considered neutral or pleasant, with passive acceptance and enjoyment being among the most popular response behaviours. A significant number of people, however, reported on attempts to cope with unwanted INMI. The most popular and effective behaviours in response to INMI were seeking out the tune in question, and musical or verbal distraction. The outcomes of this study contribute to our understanding of the aetiology of INMI, in particular within the framework of memory theory, and present testable hypotheses for future research on successful INMI coping strategies.

  6. Gate-Tuned Thermoelectric Power in Black Phosphorus.

    Science.gov (United States)

    Saito, Yu; Iizuka, Takahiko; Koretsune, Takashi; Arita, Ryotaro; Shimizu, Sunao; Iwasa, Yoshihiro

    2016-08-10

    The electric field effect is a useful means of elucidating intrinsic material properties as well as for designing functional devices. The electric-double-layer transistor (EDLT) enables the control of carrier density in a wide range, which is recently proved to be an effective tool for the investigation of thermoelectric properties. Here, we report the gate-tuning of thermoelectric power in a black phosphorus (BP) single crystal flake with the thickness of 40 nm. Using an EDLT configuration, we successfully control the thermoelectric power (S) and find that the S of ion-gated BP reached +510 μV/K at 210 K in the hole depleted state, which is much higher than the reported bulk single crystal value of +340 μV/K at 300 K. We compared this experimental data with the first-principles-based calculation and found that this enhancement is qualitatively explained by the effective thinning of the conduction channel of the BP flake and nonuniformity of the channel owing to the gate operation in a depletion mode. Our results provide new opportunities for further engineering BP as a thermoelectric material in nanoscale.

  7. Fine tuning and vacuum stability in Wilsonian effective action

    CERN Document Server

    Krajewski, Tomasz

    2014-01-01

    We have computed Wilsonian effective action in a simple model containing scalar field with quartic self-coupling which interacts via Yukawa coupling with a Dirac fermion. The model is invariant under a chiral parity operation, which can be spontaneously broken by a vev of the scalar field. We have computed explicitly Wilsonian running of relevant parameters which makes it possible to discuss in a consistent manner the issue of fine-tuning and stability of the scalar potential. This has been compared with the typical picture based on Gell-Mann-Low running. Since Wilsonian running includes automatically integration out of heavy degrees of freedom, the running differs markedly from the Gell-Mann-Low version. However, similar behaviour can be observed: scalar mass squared parameter and the quartic coupling can change sign from a positive to a negative one due to running which causes spontaneous symmetry breaking or an instability in the renormalizable part of the potential for a given range of scales. However, ca...

  8. Self-Tuning Linear Quadratic Supervisory Regulation of a Diesel Generator using Large-Signal State Estimation

    DEFF Research Database (Denmark)

    Knudsen, Jesper Viese; Bendtsen, Jan Dimon; Andersen, Palle;

    2016-01-01

    In this paper, a self-tuning linear quadratic supervisory regulator using a large-signal state estimator for a diesel driven generator set is proposed. The regulator improves operational efficiency, in comparison to current implementations, by (i) automating the initial tuning process and (ii......) enabling automated retuning capabilities. Utilizing a first principles-based nonlinear model detailed in [1], the procedure is demonstrated through simulations after real system measurements have been used for parameter identification. The regulator is able to suppress load-induced variations successfully...... throughout the operating range of the diesel generator....

  9. V-groove-based compact FBG package for thermal tuning and mechanical stability

    Science.gov (United States)

    Zhang, Li; Fang, Wei; Wang, Di; Chen, Di-Jun; Cai, Hai-Wen; Qu, Rong-Hui

    2016-04-01

    We demonstrated a V-groove-based fiber Bragg grating (FBG) package that has been glue-filled and cured to make it a bulky component with much improved mechanical stability. The V-groove can be executed with many types of materials including plastics, ceramics, semiconductors, and metals, providing an easy method for redesigning the thermal tuning performance of FBGs by selecting among a wide variety of materials and processes. We achieved more than 10-nm thermal wavelength tuning and thermal sensitivity ranging from 15 to 160 pm/K. The original FBG spectrum can be maintained without any degradation because the fiber is buried in the V-groove. The compact package does not increase the original grating length and turns the FBG into a planar waveguide grating, improving FBG applications in telecommunications, external cavity lasers, and sensing areas.

  10. Exchange Bias Tuning for Magnetoresistive Sensors by Inclusion of Non-Magnetic Impurities.

    Science.gov (United States)

    Sharma, Parikshit Pratim; Albisetti, Edoardo; Monticelli, Marco; Bertacco, Riccardo; Petti, Daniela

    2016-07-04

    The fine control of the exchange coupling strength and blocking temperature ofexchange bias systems is an important requirement for the development of magnetoresistive sensors with two pinned electrodes. In this paper, we successfully tune these parameters in top- and bottom-pinned systems, comprising 5 nm thick Co40Fe40B20 and 6.5 nm thick Ir22Mn78 films. By inserting Ru impurities at different concentrations in the Ir22Mn78 layer, blocking temperatures ranging from 220 °C to 100 °C and exchange bias fields from 200 Oe to 60 Oe are obtained. This method is then applied to the fabrication of sensors based on magnetic tunneling junctions consisting of a pinned synthetic antiferromagnet reference layer and a top-pinned sensing layer. This work paves the way towards the development of new sensors with finely tuned magnetic anisotropies.

  11. Exchange Bias Tuning for Magnetoresistive Sensors by Inclusion of Non-Magnetic Impurities

    Directory of Open Access Journals (Sweden)

    Parikshit Pratim Sharma

    2016-07-01

    Full Text Available The fine control of the exchange coupling strength and blocking temperature ofexchange bias systems is an important requirement for the development of magnetoresistive sensors with two pinned electrodes. In this paper, we successfully tune these parameters in top- and bottom-pinned systems, comprising 5 nm thick Co40Fe40B20 and 6.5 nm thick Ir22Mn78 films. By inserting Ru impurities at different concentrations in the Ir22Mn78 layer, blocking temperatures ranging from 220 °C to 100 °C and exchange bias fields from 200 Oe to 60 Oe are obtained. This method is then applied to the fabrication of sensors based on magnetic tunneling junctions consisting of a pinned synthetic antiferromagnet reference layer and a top-pinned sensing layer. This work paves the way towards the development of new sensors with finely tuned magnetic anisotropies.

  12. Tuning of mobile and stationary phase polarity for the separation of polar compounds by SFC.

    Science.gov (United States)

    Ibañez, E; Señoráns, F J

    2000-07-05

    The separation of polar compounds by supercritical-fluid chromatography (SFC) is reviewed. New developments in mobile and stationary phase tuning are reviewed for packed and packed capillary SFC. In terms of mobile phase polarity adjustment, new pure and multiple component fluids are presented. The approach of tuning the polarity of the stationary phase as a way of increasing the range of polar compounds analyzed by SFC using pure CO(2) is discussed using either silica-based or new materials as stationary phase. Chiral, liquid crystal and polymer-based stationary phases coated on particles are widely covered in this review as an interesting approach to separate polar compounds avoiding the major drawbacks associated to the use of modifiers in SFC.

  13. Frequency tuning of polarization oscillations: Toward high-speed spin-lasers

    Energy Technology Data Exchange (ETDEWEB)

    Lindemann, Markus, E-mail: markus.lindemann@rub.de; Gerhardt, Nils C.; Hofmann, Martin R. [Photonics and Terahertz Technology, Ruhr-University Bochum, 44780 Bochum (Germany); Pusch, Tobias; Michalzik, Rainer [Institute of Optoelectronics, Ulm University, 89081 Ulm (Germany)

    2016-01-25

    Spin-controlled vertical-cavity surface-emitting lasers (spin-VCSELs) offer a high potential to overcome several limitations of conventional purely charged-based laser devices. Presumably, the highest potential of spin-VCSELs lies in their ultrafast spin and polarization dynamics, which can be significantly faster than the intensity dynamics in conventional devices. Here, we experimentally demonstrate polarization oscillations in spin-VCSELs with frequencies up to 44 GHz. The results show that the oscillation frequency mainly depends on the cavity birefringence, which can be tuned by applying mechanical strain to the VCSEL structure. A tuning range of about 34 GHz is demonstrated. By measuring the polarization oscillation frequency and the birefringence governed mode splitting as a function of the applied strain simultaneously, we are able to investigate the correlation between birefringence and polarization oscillations in detail. The experimental findings are compared to numerical calculations based on the spin-flip model.

  14. Genetic Algorithm and Fuzzy Tuning PID Controller Applied on Speed Control System for Marine Diesel Engines

    Directory of Open Access Journals (Sweden)

    Naeim Farouk

    2012-11-01

    Full Text Available The degree of speed control of ship machinery effects on the economics and optimization of the machinery configuration and operation. All marine vessel ranging need some sort of speed control system to control and govern the speed of the marine diesel engines. The main focus of this study is to apply and comparative between two specific soft-computing techniques. Fuzzy logic controller and genetic algorithm to design and tuning of PID controller for applied on speed control system of marine diesel engine to get an output with better dynamic and static performance. Simulation results show that the response of system when using genetic algorithm is better and faster than when using fuzzy tuning PID controller.

  15. Viscoelastic property tuning for reducing noise radiated by switched-reluctance machines

    Science.gov (United States)

    Millithaler, Pierre; Dupont, Jean-Baptiste; Ouisse, Morvan; Sadoulet-Reboul, Émeline; Bouhaddi, Noureddine

    2017-10-01

    Switched-reluctance motors (SRM) present major acoustic drawbacks that hinder their use for electric vehicles in spite of widely-acknowledged robustness and low manufacturing costs. Unlike other types of electric machines, a SRM stator is completely encapsulated/potted with a viscoelastic resin. By taking advantage of the high damping capacity that a viscoelastic material has in certain temperature and frequency ranges, this article proposes a tuning methodology for reducing the noise emitted by a SRM in operation. After introducing the aspects the tuning process will focus on, the article details a concrete application consisting in computing representative electromagnetic excitations and then the structural response of the stator including equivalent radiated power levels. An optimised viscoelastic material is determined, with which the peak radiated levels are reduced up to 10 dB in comparison to the initial state. This methodology is implementable for concrete industrial applications as it only relies on common commercial finite-element solvers.

  16. Controlled coupling of photonic crystal cavities using photochromic tuning

    CERN Document Server

    Cai, Tao; Solomon, Glenn S; Waks, Edo

    2013-01-01

    We present a method to control the resonant coupling interaction in a coupled-cavity photonic crystal molecule by using a local and reversible photochromic tuning technique. We demonstrate the ability to tune both a two-cavity and a three-cavity photonic crystal molecule through the resonance condition by selectively tuning the individual cavities. Using this technique, we can quantitatively determine important parameters of the coupled-cavity system such as the photon tunneling rate. This method can be scaled to photonic crystal molecules with larger numbers of cavities, which provides a versatile method for studying strong interactions in coupled resonator arrays.

  17. The wave equation for stiff strings and piano tuning

    CERN Document Server

    Gràcia, Xavier

    2016-01-01

    We study the wave equation for a string with stiffness. We solve the equation and provide a uniqueness theorem with suitable boundary conditions. For a pinned string we compute the spectrum, which is slightly inharmonic. Therefore, the widespread scale of 12 equal divisions of the just octave is not the best choice to tune instruments like the piano. Basing in the theory of dissonance, we provide a way to tune the piano in order to improve its consonance. A good solution is obtained by tuning a note and its fifth by minimizing their beats.

  18. Inertia Identification and PI Parameter Tuning of PMSM Servo Drives

    Science.gov (United States)

    Lei, Huang

    2017-05-01

    The goal of this paper is to improve the performance of permanent magnet synchronous motor(PMSM) servo system by identification of the inertia parameter and auto-tuning of PI parameters. The method relies on the speed acceleration and deceleration response produced by speed ramp signals applied to a speed-controlled servo. The proposed method relies on simple numerical calculations, thus make the proposed scheme more practical. After the knowledge of the inertia parameter, the tuning of the speed control loop can be performed. The experimental results verified that the proposed identification scheme can estimate inertia parameters accurately and effectively and the control system tuned can achieve good dynamic performance.

  19. First order tune shift calculations for transverse betatron dynamics

    Energy Technology Data Exchange (ETDEWEB)

    Garavaglia, T.

    1991-09-01

    An effective Hamiltonian, with non-linear magnetic multipole terms and momentum dispersion contributions, is used to obtain the first order tune-shift results for transverse betatron motion for protons in the Superconducting Super Collider (SSC). This Hamiltonian is represented in terms of action angle variables, and analytical results are obtained using symbolic algebra methods. Mathematical derivations of the transverse multipole expansion and of the transverse betatron equations, using an invariant action and curvilinear coordinates, are given in the appendices. Numerical and graphical tune-space results are given that illustrate the dependence of tune-shifts on injection amplitude and momentum spread. 10 refs., 7 figs.

  20. Low Loss and Magnetic Field-tuned Superconducting THz Metamaterial

    CERN Document Server

    Jin, Biaobing; Engelbrecht, Sebastian; Pimenov, Andrei; Wu, Jingbo; Xu, Qinyin; Cao, Chunhai; Chen, Jian; Xu, Weiwei; Kang, Lin; Wu, Peiheng

    2010-01-01

    Superconducting terahertz (THz) metamaterial (MM) made from superconducting Nb film has been investigated using a continuous-wave THz spectroscopy with a superconducting split-coil magnet. The obtained quality factors of the resonant modes at 132 GHz and 450 GHz are about three times as large as those calculated for a metal THz MM operating at 1 K, which indicates that superconducting THz MM is a very nice candidate to achieve low loss performance. In addition, the magnetic field-tuning on superconducting THz MM is also demonstrated, which offer an alternative tuning method apart from the existed electric, optical and thermal tuning on THz MM.

  1. Filter Tuning Using the Chi-Squared Statistic

    Science.gov (United States)

    Lilly-Salkowski, Tyler

    2017-01-01

    measurements from the NASA space network (SN), which can be affected by the assumed accuracy of the TDRS satellite state at the time of the measurement.The force modelling in the EKF is also an important factor that affects the propagation accuracy and covariance sizing. The dominant force in the LEO orbit regime is the drag force caused by atmospheric drag. Accurate accounting of the drag force is especially important for the accuracy of the propagated state. The implementation of a box and wing model to improve drag estimation accuracy, and its overall effect on the covariance state is explored.The process of tuning the EKF for Aqua and Aura support is described, including examination of the measurement errors of available observation types (Doppler and range), and methods of dealing with potentially volatile atmospheric drag modeling. Predictive accuracy and the distribution of the Chi-square statistic, calculated based of the ODTK EKF solutions, are assessed versus accepted norms for the orbit regime.

  2. ‘Forcing the issue’ - Aromatic tuning facilitates stimulus-independent modulation of a two-component signaling circuit

    DEFF Research Database (Denmark)

    Nørholm, Morten; von Heijne, Gunnar; Draheim, Roger R.

    2014-01-01

    desirable because particular physiological or developmental processes could be controlled for biotechnological purposes without the need to identify the stimulus itself. Here, we demonstrate that aromatic tuning, i.e., repositioning the aromatic residues commonly found at the cytoplasmic end of the receptor...... receptors were not locked in a single conformation. We also noted that circuits containing aromatically tuned variants became more sensitive to changes in the receptor concentration than their wild-type counterpart, suggesting a new way to study mechanisms underpinning receptor concentration......-dependent robustness. We believe that aromatic tuning has several advantages compared to previous methods aimed at stimulus-independent modulation of receptors and that it will be generally applicable to a wide-range of two-component circuits....

  3. An electrical tuning mechanism in turtle cochlear hair cells.

    Science.gov (United States)

    Crawford, A C; Fettiplace, R

    1981-03-01

    1. Intracellular recordings were made from single cochlear hair cells in the isolated half-head of the turtle. The electrical responses of the cells were recorded under two conditions: (a) when the ear was stimulated with low-intensity tones of different frequencies and (b) when current steps were injected through the intracellular electrode. The aim of the experiments was to evaluate the extent to which the cochlea's frequency selectivity could be accounted for by the electrical properties of the hair cells.2. At low levels of acoustic stimulation, the amplitude of the hair cell's receptor potential was proportional to sound pressure. The linear tuning curve, which is defined as the sensitivity of the cell as a function of frequency when the cell is operating in its linear range, was measured for a number of hair cells with characteristic frequencies from 86 Hz to 425 Hz.3. A rectangular current passed into a hair cell elicited a membrane potential change consisting of a damped oscillation superimposed on a step. Small currents produced symmetrical oscillations at the beginning and end of the pulse. Larger currents increased the initial ringing frequency if depolarizing and decreased it if hyperpolarizing.4. For small currents the frequency of the oscillations and the quality factor (Q) of the electrical resonance derived from the decay of the oscillations were close to the characteristic frequency and Q of the hair-cell linear tuning curve obtained from sound presentations.5. The hair cell's membrane potential change to small-current pulses or low-intensity tone bursts could be largely described by representing the hair cell as a simple electrical resonator consisting of an inductance, resistor and capacitor.6. When step displacements of 29-250 nm were applied to a micropipette, placed just outside a hair cell in the basilar papilla, an initial periodic firing of impulses could be recorded from single fibres in the auditory nerve. Currents of up to 1 nA, injected

  4. Tuning flux: autophagy as a target of heart disease therapy

    Science.gov (United States)

    Xie, Min; Morales, Cyndi R.; Lavandero, Sergio; Hill, Joseph A.

    2013-01-01

    Purpose of review Despite maximum medical and mechanical support therapy, heart failure remains a relentlessly progressive disorder with substantial morbidity and mortality. Autophagy, an evolutionarily conserved process of cellular cannibalization, has been implicated in virtually all forms of cardiovascular disease. Indeed, its role is context dependent, antagonizing or promoting disease depending on the circumstance. Here, we review current understanding of the role of autophagy in the pathogenesis of heart failure and explore this pathway as a target of therapeutic intervention. Recent findings In preclinical models of heart disease, cardiomyocyte autophagic flux is activated; indeed, its role in disease pathogenesis is the subject of intense investigation to define mechanism. Similarly, in failing human heart of a variety of etiologies, cardiomyocyte autophagic activity is upregulated, and therapy, such as with mechanical support systems, elicits declines in autophagy activity. However, when suppression of autophagy is complete, rapid and catastrophic cell death occurs, consistent with a model in which basal autophagic flux is required for proteostasis. Thus, a narrow zone of ‘optimal’ autophagy seems to exist. The challenge moving forward is to tune the stress-triggered autophagic response within that ‘sweet spot’ range for therapeutic benefit. Summary Whereas we have known for some years of the participation of lysosomal mechanisms in heart disease, it is only recently that upstream mechanisms (autophagy) are being explored. The challenge for the future is to dissect the underlying circuitry and titrate the response into an optimal, proteostasis-promoting range in hopes of mitigating the ever-expanding epidemic of heart failure. PMID:21415729

  5. RF Tuning Schemes for J-PARC DTL and SDTL

    CERN Document Server

    Ikegami, M

    2004-01-01

    J-PARC linac consists of a 3 MeV RFQ linac, a 50 MeV DTL (Drift Tube Linac), a 190 MeV SDTL (Separate-type DTL), and a 400 MeV ACS (Annular-Coupled Structure) linac. In high-current proton linacs, precise tuning of RF amplitude and phase is indispensable to reduce uncontrolled beam loss and beam-quality deterioration. Especially, accurate RF tuning is essential for J-PARC linac, because requirement for the momentum spread is extremely severe to enable effective injection to the succeeding RCS (Rapid Cycling Synchrotron). In this paper, planned tuning schemes for the DTL and SDTL are presented together with the beam diagnostic layout for the tuning.

  6. Human face processing is tuned to sexual age preferences

    DEFF Research Database (Denmark)

    Ponseti, J; Granert, O; van Eimeren, T

    2014-01-01

    . In paedophilia, sexual attraction is directed to sexually immature children. Therefore, we hypothesized that brain networks that normally are tuned to mature faces of the preferred gender show an abnormal tuning to sexual immature faces in paedophilia. Here, we use functional magnetic resonance imaging (f......Human faces can motivate nurturing behaviour or sexual behaviour when adults see a child or an adult face, respectively. This suggests that face processing is tuned to detecting age cues of sexual maturity to stimulate the appropriate reproductive behaviour: either caretaking or mating......MRI) to test directly for the existence of a network which is tuned to face cues of sexual maturity. During fMRI, participants sexually attracted to either adults or children were exposed to various face images. In individuals attracted to adults, adult faces activated several brain regions significantly more...

  7. Tuning of active vibration controllers for ACTEX by genetic algorithm

    Science.gov (United States)

    Kwak, Moon K.; Denoyer, Keith K.

    1999-06-01

    This paper is concerned with the optimal tuning of digitally programmable analog controllers on the ACTEX-1 smart structures flight experiment. The programmable controllers for each channel include a third order Strain Rate Feedback (SRF) controller, a fifth order SRF controller, a second order Positive Position Feedback (PPF) controller, and a fourth order PPF controller. Optimal manual tuning of several control parameters can be a difficult task even though the closed-loop control characteristics of each controller are well known. Hence, the automatic tuning of individual control parameters using Genetic Algorithms is proposed in this paper. The optimal control parameters of each control law are obtained by imposing a constraint on the closed-loop frequency response functions using the ACTEX mathematical model. The tuned control parameters are then uploaded to the ACTEX electronic control electronics and experiments on the active vibration control are carried out in space. The experimental results on ACTEX will be presented.

  8. CLIC BDS Tuning, Alignment and Feedbacks Integrated Simulations

    CERN Document Server

    Dalena, B; Schulte, D; Snuverink, J; Tomas, R; Jones, J; Latina, A; Resta, J

    2010-01-01

    The CLIC BDS tuning, alignment and feedbacks studies have been typically performed independently and only over particular sections of the BDS. An effort is being put to integrate all these procedures to realistically evaluate the luminosity performance.

  9. Geometrical tuning of nanoscale split-ring resonators

    DEFF Research Database (Denmark)

    Jeppesen, Claus; Kristensen, Anders; Xiao, Sanshui;

    2010-01-01

    We investigate the capacitance tuning of nanoscale split-ring resonators. An LC-model predicts a simple dependence of resonance frequency on slit aspect ratio. Experimental and numerical data follow the predictions of the LC-model....

  10. Gain and frequency tuning within the mouse cochlear apex

    Energy Technology Data Exchange (ETDEWEB)

    Oghalai, John S.; Raphael, Patrick D. [Department of Otolaryngology, Stanford University School of Medicine, Stanford, California (United States); Gao, Simon [Department of Otolaryngology, Stanford University School of Medicine, Stanford, California (United States); Department of Bioengineering, Rice University, Houston, Texas (United States); Lee, Hee Yoon [Department of Otolaryngology, Stanford University School of Medicine, Stanford, California (United States); Department of Electrical Engineering, Stanford University, Stanford, California (United States); Groves, Andrew K. [Department of Neuroscience, Department of Molecular and Human Genetics, and Program in Developmental Biology, Baylor College of Medicine, Houston, Texas (United States); Zuo, Jian [Department of Developmental Neurobiology, St. Jude Children’s Research Hospital, Memphis, Tennessee (United States); Applegate, Brian E. [Department of Biomedical Engineering, Texas A& M University, College Station, Texas (United States)

    2015-12-31

    Normal mammalian hearing requires cochlear outer hair cell active processes that amplify the traveling wave with high gain and sharp tuning, termed cochlear amplification. We have used optical coherence tomography to study cochlear amplification within the apical turn of the mouse cochlea. We measured not only classical basilar membrane vibratory tuning curves but also vibratory responses from the rest of the tissues that compose the organ of Corti. Basilar membrane tuning was sharp in live mice and broad in dead mice, whereas other regions of the organ of Corti demonstrated phase shifts consistent with additional filtering beyond that provided by basilar membrane mechanics. We use these experimental data to support a conceptual framework of how cochlear amplification is tuned within the mouse cochlear apex. We will also study transgenic mice with targeted mutations that affect different biomechanical aspects of the organ of Corti in an effort to localize the underlying processes that produce this additional filtering.

  11. Multiple Tune Jumps to Overcome Horizontal Depolarizing Resonances

    Science.gov (United States)

    Huang, H.; Ahrens, L. A.; Bai, M.; Brown, K. A.; Dutheil, Y.; Gardner, C.; Glenn, J. W.; Lin, F.; Mackay, W. W.; Meot, F.; Poblaguev, A.; Ranjbar, V.; Roser, T.; Schoefer, V.; Tepikian, S.; Tsoupas, N.; Yip, K.; Zelenski, A.; Zeno, K.

    2016-02-01

    Imperfection and vertical intrinsic depolarizing resonances have been overcome by the two partial Siberian snakes in the Alternative Gradient Synchrotron(AGS). The relatively weak but numerous horizontal resonances are the main source of polarization loss in the AGS. A pair of horizontal tune jump quads have been used to overcome these weak resonances. The locations of the two quads have to be chosen such that the disturbance to the beam optics is minimum. The emittance growth has to be mitigated for this method to work. In addition, this technique needs very accurate jump timing. Using two partial Siberian snakes, with vertical tune inside the spin tune gap and 80% polarization at AGS injection, polarized proton beam had reached 1.5 × 1011 proton per bunch with 65% polarization. With the tune jump timing optimized and emittance preserved, more than 70% polarization with 2 × 1011 protons per bunch has been achieved.

  12. Acousto-optic filter for electronic laser tuning

    Science.gov (United States)

    Harris, S. E.

    1972-01-01

    Electronically tunable lithium niobate filter utilizes acoustic-optic diffraction for tuning laser to desired frequencies. Filter placed inside laser cavity diffracts incident optical signal of one polarization into orthogonal polarization by collinearly propagating acoustic beam to desired wavelength.

  13. OSKI: A Library of Automatically Tuned Sparse Matrix Kernels

    Energy Technology Data Exchange (ETDEWEB)

    Vuduc, R; Demmel, J W; Yelick, K A

    2005-07-19

    The Optimized Sparse Kernel Interface (OSKI) is a collection of low-level primitives that provide automatically tuned computational kernels on sparse matrices, for use by solver libraries and applications. These kernels include sparse matrix-vector multiply and sparse triangular solve, among others. The primary aim of this interface is to hide the complex decision-making process needed to tune the performance of a kernel implementation for a particular user's sparse matrix and machine, while also exposing the steps and potentially non-trivial costs of tuning at run-time. This paper provides an overview of OSKI, which is based on our research on automatically tuned sparse kernels for modern cache-based superscalar machines.

  14. OSKI: A library of automatically tuned sparse matrix kernels

    Science.gov (United States)

    Vuduc, Richard; Demmel, James W.; Yelick, Katherine A.

    2005-01-01

    The Optimized Sparse Kernel Interface (OSKI) is a collection of low-level primitives that provide automatically tuned computational kernels on sparse matrices, for use by solver libraries and applications. These kernels include sparse matrix-vector multiply and sparse triangular solve, among others. The primary aim of this interface is to hide the complex decisionmaking process needed to tune the performance of a kernel implementation for a particular user's sparse matrix and machine, while also exposing the steps and potentially non-trivial costs of tuning at run-time. This paper provides an overview of OSKI, which is based on our research on automatically tuned sparse kernels for modern cache-based superscalar machines.

  15. An improved auto-tuning scheme for PI controllers.

    Science.gov (United States)

    Mudi, Rajani K; Dey, Chanchal; Lee, Tsu-Tian

    2008-01-01

    Ziegler-Nichols tuned PI and PID controllers are usually found to provide poor performances for high-order and nonlinear systems. In this study, an improved auto-tuning scheme is presented for Ziegler-Nichols tuned PI controllers (ZNPICs). With a view to improving the transient response, the proportional and integral gains of the proposed controller are continuously modified based on the current process trend. The proposed controller is tested for a number of high-order linear and nonlinear dead-time processes under both set-point change and load disturbance. It exhibits significantly improved performance compared to ZNPIC, and Refined Ziegler-Nichols tuned PI controller (RZNPIC). Robustness of the proposed scheme is established by varying the controller parameters as well as the dead-time of the process under control.

  16. Application of Evolutionary Computation in Automotive Powertrain Mount Tuning

    Directory of Open Access Journals (Sweden)

    Anab Akanda

    2006-01-01

    Full Text Available Engine mount tuning is a multi-disciplinary exercise since it affects Idle-shake, Road-shake and power-train noise response. Engine inertia is often used as a tuned absorber for controlling suspension resonance related road-shake issues. Last but not least, vehicle ride and handling may also be affected by mount tuning. In this work, Torque-Roll-Axis (TRA decoupling of the rigid powertrain was used as a starting point for mount tuning. Nodal point of flexible powertrain bending was used to define the envelop for transmission mount locations. The frequency corresponding to the decoupled roll mode of the rigid powertrain was then adjusted for idle-shake and road-shake response management.

  17. Betatron tune measurement with the LHC damper using a GPU

    CERN Document Server

    Dubouchet, Frédéric; Höfle, Wolfgang

    This thesis studies a possible futur implementation of a betatron tune measure- ment in the Large Hadron Collider (LHC) at European organization for nuclear research (CERN) using a General Purpose Graphic Processing Unit (GPGPU) to analyse data acquired with the LHC transverse transverse damper (ADT). The present hardware and future possible implementations using ADT acquisi- tions and Graphic Processing Unit (GPU) computing are described. The ADT data have to be processed to extract the betatron tune. To compute the tune, the signal is transformed from the time domain to the frequency domain using Fast Fourier Transform (FFT) on GPUs. We show that it is possible to achieve one order of magnitude faster FFTs on a Fermi generation GPU than what can be done using a i7 generation Central Processing Unit (CPU). This makes online per bunch FFT computation and betatron tune measurement possible.

  18. Tuned mass absorbers on damped structures under random load

    DEFF Research Database (Denmark)

    Krenk, Steen; Høgsberg, Jan Becker

    2008-01-01

    A substantial literature exists on the optimal choice of parameters of a tuned mass absorber on a structure excited by a force or by ground acceleration with random characteristics in the form of white noise. In the absence of structural damping the optimal frequency tuning is determined from...... the mass ratio alone, and the damping can be determined subsequently. Only approximate results are available for the influence of damping in the original structure, typically in the form of series expansions. In the present paper it is demonstrated that for typical mass ratios in the order of a few percent...... the classic stochastic frequency tuning gives the same standard deviation of the response amplitude within a margin of 0.001 as when using the classic frequency tuning for harmonic load variation, and then optimizing the damping separately. Simple approximate, but very accurate, expressions are obtained...

  19. Tuning the work-function via strong coupling.

    Science.gov (United States)

    Hutchison, James A; Liscio, Andrea; Schwartz, Tal; Canaguier-Durand, Antoine; Genet, Cyriaque; Palermo, Vincenzo; Samorì, Paolo; Ebbesen, Thomas W

    2013-05-01

    The tuning of the molecular material work-function via strong coupling with vacuum electromagnetic fields is demonstrated. Kelvin probe microscopy extracts the surface potential (SP) changes of a photochromic molecular film on plasmonic hole arrays and inside Fabry-Perot cavities. Modulating the optical cavity resonance or the photochromic film effectively tunes the work-function, suggesting a new tool for tailoring material properties.

  20. Local Quantum Dot Tuning on Photonic Crystal Chips

    CERN Document Server

    Faraon, Andrei; Fushman, Ilya; Stoltz, Nick; Petroff, Pierre; Vuckovic, Jelena

    2007-01-01

    Quantum networks based on InGaAs quantum dots embedded in photonic crystal devices rely on QDs being in resonance with each other and with the cavities they are embedded in. We developed a new technique based on temperature tuning to spectrally align different quantum dots located on the same chip. The technique allows for up to 1.8nm reversible on-chip quantum dot tuning.

  1. HOM Coupler Notch Filter Tuning for the European XFEL Cavities

    OpenAIRE

    Sulimov, Alexey

    2015-01-01

    The notch filter (NF) tuning prevents the extraction of fundamental mode (1.3 GHz) RF power through Higher Order Modes (HOM) couplers. The procedure of NF tuning was optimized at the beginning of serial European XFEL cavities production. It allows keeping the filter more stable against temperature and pressure changes during cavity cool down. Some statistics of NF condition during cavities and modules cold tests is presented.

  2. MD 1691: Active halo control using tune ripple at injection

    CERN Document Server

    Garcia Morales, Hector; Bruce, Roderik; Redaelli, Stefano; Fitterer, Miriam; Fiascaris, Maria; Nisbet, David; Thiesen, Hugues; Valentino, Gianluca; Xu, Chen; CERN. Geneva. ATS Department

    2017-01-01

    In this MD we performed halo excitation through tune ripple. This consists in an excitation that introduces new resonance sidebands around the existing resonance lines. In presence of sufficient detuning with amplitude, these sidebands can in principle affect only the dynamics of the halo particles at large amplitudes. Tune ripple was induced through a current modulation of the warm trim quadrupoles in IR7. This is the first time this method is experimentally tested at the LHC.

  3. Genetic Algorithm Tuned Fuzzy Logic for Gliding Return Trajectories

    Science.gov (United States)

    Burchett, Bradley T.

    2003-01-01

    The problem of designing and flying a trajectory for successful recovery of a reusable launch vehicle is tackled using fuzzy logic control with genetic algorithm optimization. The plant is approximated by a simplified three degree of freedom non-linear model. A baseline trajectory design and guidance algorithm consisting of several Mamdani type fuzzy controllers is tuned using a simple genetic algorithm. Preliminary results show that the performance of the overall system is shown to improve with genetic algorithm tuning.

  4. Iterative Controller Tuning for Process with Fold Bifurcations

    DEFF Research Database (Denmark)

    Huusom, Jakob Kjøbsted; Poulsen, Niels Kjølstad; Jørgensen, Sten Bay

    2007-01-01

    Processes involving fold bifurcation are notoriously difficult to control in the vicinity of the fold where most often optimal productivity is achieved . In cases with limited process insight a model based control synthesis is not possible. This paper uses a data driven approach with an improved...... version of iterative feedback tuning to optimizing a closed loop performance criterion, as a systematic tool for tuning process with fold bifurcations....

  5. Local tuning of photonic crystal cavities using chalcogenide glasses

    CERN Document Server

    Faraon, Andrei; Bulla, Douglas; Luther-Davies, Barry; Eggleton, Benjamin J; Stoltz, Nick; Petroff, Pierre; Vuckovic, Jelena

    2007-01-01

    We demonstrate a method to locally change the refractive index in planar optical devices by photodarkening of a thin chalcogenide glass layer deposited on top of the device. The method is used to tune the resonance of GaAs-based photonic crystal cavities by up to 3 nm at 940 nm, with only 5% deterioration in cavity quality factor. The method has broad applications for postproduction tuning of photonic devices.

  6. Covert attention enhances letter identification without affecting channel tuning.

    Science.gov (United States)

    Talgar, Cigdem P; Pelli, Denis G; Carrasco, Marisa

    2004-02-02

    Directing covert attention to the target location enhances sensitivity, but it is not clear how this enhancement comes about. Knowing that a single spatial frequency channel mediates letter identification, we use the critical-band-masking paradigm to investigate whether covert attention affects the spatial frequency tuning of that channel. We find that directing attention to the target location halves threshold energy without affecting the channel's spatial frequency tuning.

  7. Tuning Conductance in Aromatic Molecules: Constructive and Counteractive Substituent Effects

    DEFF Research Database (Denmark)

    Garner, Marc H.; Solomon, Gemma C.; Strange, Mikkel

    2016-01-01

    Destructive quantum interference in aromatic hydrocarbons can be tuned using chemical substituents; however, classical chemical intuition is not enough to explain the effects on electron transport. Using Huckel theory and density functional theory calculations, in combination with the Landauer....... This insight should be useful when substituents are to be used for tuning destructive quantum interference features in the transmission relative to the Fermi energy of the electrodes....

  8. Method and apparatus for coherent burst ranging

    Science.gov (United States)

    Wachter, E.A.; Fisher, W.G.

    1998-04-28

    A high resolution ranging method is described utilizing a novel modulated waveform, hereafter referred to as coherent burst modulation. In the coherent burst method, high frequency modulation of an acoustic or electromagnetic transmitter, such as a laser, is performed at a modulation frequency. This modulation frequency is transmitted quasi-continuously in the form of interrupted bursts of radiation. Energy from the transmitter is directed onto a target, interacts with the target, and the returning energy is collected. The encoded burst pattern contained in the collected return signal is detected coherently by a receiver that is tuned so as to be principally sensitive to the modulation frequency. The receiver signal is processed to determine target range using both time-of-flight of the burst envelope and phase shift of the high frequency modulation. This approach effectively decouples the maximum unambiguous range and range resolution relationship of earlier methods, thereby allowing high precision ranging to be conducted at arbitrarily long distances using at least one burst of encoded energy. The use of a receiver tuned to the high frequency modulation contained within the coherent burst vastly improves both sensitivity in the detection of the target return signal and rejection of background interferences, such as ambient acoustic or electromagnetic noise. Simultaneous transmission at several energies (or wavelengths) is possible by encoding each energy with a separate modulation frequency or pattern; electronic demodulation at the receiver allows the return pattern for each energy to be monitored independently. Radial velocity of a target can also be determined by monitoring change in phase shift of the return signal as a function of time. 12 figs.

  9. Emissivity Tuned Emitter for RTPV Power Sources

    Energy Technology Data Exchange (ETDEWEB)

    Carl M. Stoots; Robert C. O' Brien; Troy M. Howe

    2012-03-01

    Every mission launched by NASA to the outer planets has produced unexpected results. The Voyager I and II, Galileo, and Cassini missions produced images and collected scientific data that totally revolutionized our understanding of the solar system and the formation of the planetary systems. These missions were enabled by the use of nuclear power. Because of the distances from the Sun, electrical power was produced using the radioactive decay of a plutonium isotope. Radioisotopic Thermoelectric Generators (RTGs) used in the past and currently used Multi-Mission RTGs (MMRTGs) provide power for space missions. Unfortunately, RTGs rely on thermocouples to convert heat to electricity and are inherently inefficient ({approx} 3-7% thermal to electric efficiency). A Radioisotope Thermal Photovoltaic (RTPV) power source has the potential to reduce the specific mass of the onboard power supply by increasing the efficiency of thermal to electric conversion. In an RTPV, a radioisotope heats an emitter, which emits light to a photovoltaic (PV) cell, which converts the light into electricity. Developing an emitter tuned to the desired wavelength of the photovoltaic is a key part in increasing overall performance. Researchers at the NASA Glenn Research Center (GRC) have built a Thermal Photovoltaic (TPV) system, that utilizes a simulated General Purpose Heat Source (GPHS) from a MMRTG to heat a tantalum emitter. The GPHS is a block of graphite roughly 10 cm by 10 cm by 5 cm. A fully loaded GPHS produces 250 w of thermal power and weighs 1.6 kgs. The GRC system relies on the GPHS unit radiating at 1200 K to a tantalum emitter that, in turn, radiates light to a GaInAs photo-voltaic cell. The GRC claims system efficiency of conversion of 15%. The specific mass is around 167 kg/kWe. A RTPV power source that utilized a ceramic or ceramic-metal (cermet) matrix would allow for the combination of the heat source, canister, and emitter into one compact unit, and allow variation in size

  10. Highly-efficient thermally-tuned resonant optical filters.

    Science.gov (United States)

    Cunningham, John E; Shubin, Ivan; Zheng, Xuezhe; Pinguet, Thierry; Mekis, Attila; Luo, Ying; Thacker, Hiren; Li, Guoliang; Yao, Jin; Raj, Kannan; Krishnamoorthy, Ashok V

    2010-08-30

    We demonstrate spectral tunability for microphotonic add-drop filters manufactured as ring resonators in a commercial 130 nm SOI CMOS technology. The filters are provisioned with integrated heaters built in CMOS for thermal tuning. Their thermal impedance has been dramatically increased by the selective removal of the SOI handler substrate under the device footprint using a bulk silicon micromachining process. An overall ~20x increase in the tuning efficiency has been demonstrated with a 100 µm radius ring as compared to a pre-micromachined device. A total of 3.9 mW of applied tuning power shifts the filter resonant peak across one free spectral node of the device. The Q-factor of the resonator remains unchanged after the co-integration process and hence this device geometry proves to be fully CMOS compatible. Additionally, after the cointegration process our result of 2π shift with 3.9 mW power is among the best tuning performances for this class of devices. Finally, we examine scaling the tuning efficiency versus device footprint to develop a different performance criterion for an easier comparison to evaluate thermal tuning. Our criterion is defined as the unit of power to shift the device resonance by a full 2π phase shift.

  11. Tuning and backreaction in F-term axion monodromy inflation

    Directory of Open Access Journals (Sweden)

    Arthur Hebecker

    2015-05-01

    Full Text Available We continue the development of axion monodromy inflation, focusing in particular on the backreaction of complex structure moduli. In our setting, the shift symmetry comes from a partial large complex structure limit of the underlying type IIB orientifold or F-theory fourfold. The coefficient of the inflaton term in the superpotential has to be tuned small to avoid conflict with Kähler moduli stabilisation. To allow such a tuning, this coefficient necessarily depends on further complex structure moduli. At large values of the inflaton field, these moduli are then in danger of backreacting too strongly. To avoid this, further tunings are necessary. In weakly coupled type IIB theory at the orientifold point, implementing these tunings appears to be difficult if not impossible. However, fourfolds or models with mobile D7-branes provide enough structural freedom. We calculate the resulting inflaton potential and study the feasibility of the overall tuning given the limited freedom of the flux landscape. Our preliminary investigations suggest that, even imposing all tuning conditions, the remaining choice of flux vacua can still be large enough for such models to provide a promising path to large-field inflation in string theory.

  12. Tuning and backreaction in F-term axion monodromy inflation

    Energy Technology Data Exchange (ETDEWEB)

    Hebecker, Arthur, E-mail: A.Hebecker@ThPhys.Uni-Heidelberg.de; Mangat, Patrick, E-mail: P.Mangat@ThPhys.Uni-Heidelberg.de; Rompineve, Fabrizio, E-mail: F.Rompineve@ThPhys.Uni-Heidelberg.de; Witkowski, Lukas T., E-mail: L.Witkowski@ThPhys.Uni-Heidelberg.de

    2015-05-15

    We continue the development of axion monodromy inflation, focusing in particular on the backreaction of complex structure moduli. In our setting, the shift symmetry comes from a partial large complex structure limit of the underlying type IIB orientifold or F-theory fourfold. The coefficient of the inflaton term in the superpotential has to be tuned small to avoid conflict with Kähler moduli stabilisation. To allow such a tuning, this coefficient necessarily depends on further complex structure moduli. At large values of the inflaton field, these moduli are then in danger of backreacting too strongly. To avoid this, further tunings are necessary. In weakly coupled type IIB theory at the orientifold point, implementing these tunings appears to be difficult if not impossible. However, fourfolds or models with mobile D7-branes provide enough structural freedom. We calculate the resulting inflaton potential and study the feasibility of the overall tuning given the limited freedom of the flux landscape. Our preliminary investigations suggest that, even imposing all tuning conditions, the remaining choice of flux vacua can still be large enough for such models to provide a promising path to large-field inflation in string theory.

  13. Optimal tuning for a classical wind turbine controller

    DEFF Research Database (Denmark)

    Tibaldi, Carlo; Hansen, Morten Hartvig; Henriksen, Lars Christian

    2012-01-01

    Fine tuning of controllers for pitch-torque regulated wind turbines is an opportunity to improve the wind turbine performances and reduce the cost of energy without applying any changes to the design. For this purpose, a method for automatically tune a classical controller based on numerical opti...... tuning that improves the wind turbine performances. For the case study selected in this work, a 2% cost of energy reduction is achieved with seven iterations.......Fine tuning of controllers for pitch-torque regulated wind turbines is an opportunity to improve the wind turbine performances and reduce the cost of energy without applying any changes to the design. For this purpose, a method for automatically tune a classical controller based on numerical...... optimization is developed and tested. To have a better understanding of the problem a parametric analysis of the wind turbine performances due to changes in the controller parameters is rst performed. Thereafter results obtained with the automatic tuning show that is possible to identify a ner controller...

  14. Optimal tuning for a classical wind turbine controller

    DEFF Research Database (Denmark)

    Tibaldi, Carlo; Hansen, Morten Hartvig; Henriksen, Lars Christian

    2014-01-01

    Fine tuning of controllers for pitch-torque regulated wind turbines is an opportunity to improve the wind turbine performances and reduce the cost of energy without applying any changes to the design. For this purpose, a method for automatically tune a classical controller based on numerical opti...... tuning that improves the wind turbine performances. For the case study selected in this work, a 2% cost function reduction is achieved with seven iterations.......Fine tuning of controllers for pitch-torque regulated wind turbines is an opportunity to improve the wind turbine performances and reduce the cost of energy without applying any changes to the design. For this purpose, a method for automatically tune a classical controller based on numerical...... optimization is developed and tested. To have a better understanding of the problem a parametric analysis of the wind turbine performances due to changes in the controller parameters is first performed. Thereafter results obtained with the automatic tuning show that is possible to identify a finer controller...

  15. Fine-tuning and the stability of recurrent neural networks.

    Directory of Open Access Journals (Sweden)

    David MacNeil

    Full Text Available A central criticism of standard theoretical approaches to constructing stable, recurrent model networks is that the synaptic connection weights need to be finely-tuned. This criticism is severe because proposed rules for learning these weights have been shown to have various limitations to their biological plausibility. Hence it is unlikely that such rules are used to continuously fine-tune the network in vivo. We describe a learning rule that is able to tune synaptic weights in a biologically plausible manner. We demonstrate and test this rule in the context of the oculomotor integrator, showing that only known neural signals are needed to tune the weights. We demonstrate that the rule appropriately accounts for a wide variety of experimental results, and is robust under several kinds of perturbation. Furthermore, we show that the rule is able to achieve stability as good as or better than that provided by the linearly optimal weights often used in recurrent models of the integrator. Finally, we discuss how this rule can be generalized to tune a wide variety of recurrent attractor networks, such as those found in head direction and path integration systems, suggesting that it may be used to tune a wide variety of stable neural systems.

  16. PI and PID controller tuning rules for time delay processes: a summary. Part 2: PID controller tuning rules

    OpenAIRE

    O'Dwyer, Aidan

    1999-01-01

    A summary of tuning rules for the PID control of single input, single output (SISO) processes with time delay, modeled in stable first order lag plus time delay (FOLPD) form, is provided in this part of the paper.

  17. Strategy of tuning gene expression ratio in prokaryotic cell from perspective of noise and correlation.

    Science.gov (United States)

    Li, Rui; Xu, Liufang; Shi, Hualin

    2015-01-21

    Genes are organized into operons in procaryote, and these genes in one operon generally have related functions. However, genes in the same operon are usually not equally expressed, and the ratio needs to be fine-tuned for specific functions. We examine the difference of gene expression noise and correlation when tuning the expression level at the transcriptional or translational level in a bicistronic operon driven by a constitutive or a two-state promoter. We get analytic results for the noise and correlation of gene expression levels, which is confirmed by our stochastic simulations. Both the noise and the correlation of gene expressions in an operon with a two-state promoter are higher than in an operon with a constitutive promoter. Premature termination of mRNA induced by transcription terminator in the intergenic region or changing translation rates can tune the protein ratio at the transcriptional level or at the translational level. We find that gene expression correlation between promoter-proximal and promoter-distal genes at the protein level decreases as termination increases. In contrast, changing translation rates in the normal range almost does not alter the correlation. This explains why the translation rate is a key factor of modulating gene expressions in an operon. Our results can be useful to understand the relationship between the operon structure and the biological function of a gene network, and also may help in synthetic biology design. Copyright © 2014 Elsevier Ltd. All rights reserved.

  18. Design optimizations of phase noise, power consumption and frequency tuning for VCO

    Science.gov (United States)

    Nan, Chen; Shengxi, Diao; Lu, Huang; Xuefei, Bai; Fujiang, Lin

    2013-09-01

    To meet the requirements of the low power Zigbee system, VCO design optimizations of phase noise, power consumption and frequency tuning are discussed in this paper. Both flicker noise of tail bias transistors and up-conversion of flicker noise from cross-coupled pair are reduced by improved self-switched biasing technology, leading to low close-in phase noise. Low power is achieved by low supply voltage and triode region biasing. To linearly tune the frequency and get constant gain, distributed varactor structure is adopted. The proposed VCO is fabricated in SMIC 0.18-μm CMOS process. The measured linear tuning range is from 2.38 to 2.61 GHz. The oscillator exhibits low phase noise of -77.5 dBc/Hz and -122.8 dBc/Hz at 10 kHz and 1 MHz offset, respectively, at 2.55 GHz oscillation frequency while dissipating 2.7 mA from 1.2 V supply voltage, which well meet design specifications.

  19. Probing cochlear tuning and tonotopy in the tiger using otoacoustic emissions.

    Science.gov (United States)

    Bergevin, Christopher; Walsh, Edward J; McGee, JoAnn; Shera, Christopher A

    2012-08-01

    Otoacoustic emissions (sound emitted from the ear) allow cochlear function to be probed noninvasively. The emissions evoked by pure tones, known as stimulus-frequency emissions (SFOAEs), have been shown to provide reliable estimates of peripheral frequency tuning in a variety of mammalian and non-mammalian species. Here, we apply the same methodology to explore peripheral auditory function in the largest member of the cat family, the tiger (Panthera tigris). We measured SFOAEs in 9 unique ears of 5 anesthetized tigers. The tigers, housed at the Henry Doorly Zoo (Omaha, NE), were of both sexes and ranged in age from 3 to 10 years. SFOAE phase-gradient delays are significantly longer in tigers--by approximately a factor of two above 2 kHz and even more at lower frequencies--than in domestic cats (Felis catus), a species commonly used in auditory studies. Based on correlations between tuning and delay established in other species, our results imply that cochlear tuning in the tiger is significantly sharper than in domestic cat and appears comparable to that of humans. Furthermore, the SFOAE data indicate that tigers have a larger tonotopic mapping constant (mm/octave) than domestic cats. A larger mapping constant in tiger is consistent both with auditory brainstem response thresholds (that suggest a lower upper frequency limit of hearing for the tiger than domestic cat) and with measurements of basilar-membrane length (about 1.5 times longer in the tiger than domestic cat).

  20. A simulation of the performance of a self-tuning energy harvesting cantilever beam

    Science.gov (United States)

    Kaplan, J. L.; Bonello, P.; Alalwan, M.

    2016-09-01

    A vibration energy harvester is typically a cantilever beam made up of one or two layers of piezoelectric material that is clamped at one end to a vibrating host structure. The harvester is typically tuned to the frequency of the ambient vibration to ensure maximum power generation. One method to ensure that the system stays tuned in the presence of a varying frequency is to attach a mass to the cantilever and apply a control system to adjust its position along the cantilever according to the ambient frequency. This paper presents a simulation of the performance of such a system, based on a distributed parameter electromechanical model of the sliding-mass beam. A variety of control systems are used to adjust the position of the movable mass during operation and are compared for their efficacy in maintaining resonance over a varying excitation frequency. It was found that the resonance frequency of a bimorph cantilever VEH (Vibration Energy Harvester) could be successfully tuned over a wide frequency range. Moreover, it is also found that much of the voltage output reduction at higher frequencies could be compensated for by a separate control system used to adjust the capacitor load.