WorldWideScience

Sample records for self-injection phase locking

  1. Self-injection locking of the DFB laser through an external ring fiber cavity: Application for phase sensitive OTDR acoustic sensor

    Directory of Open Access Journals (Sweden)

    J.L. Bueno Escobedo

    Full Text Available Self-injection locking of DFB laser implemented through the laser coupling with an external fiber optic ring cavity allows its direct employment as an interrogating light source for a phase sensitive OTDR acoustic sensor. Distributed detection and localization of dynamic perturbations of the optical fiber is experimentally demonstrated at the distance of 9270 m. Keywords: Self-injection locking, Optical fiber resonator, φ-OTDR

  2. Self-injection locking of the DFB laser through an external ring fiber cavity: Polarization behavior

    Directory of Open Access Journals (Sweden)

    J.L. Bueno Escobedo

    Full Text Available We study stability of self-injection locking realized with DFB laser coupled with an external fiber optic ring cavity. Polarization behavior of the radiation circulating in the feedback loop is reported. Two regimes of mode hopping have been observed; one of them is accompanied by polarization bistability involving two orthogonal polarization states. Keywords: Self-injection locking, Polarization, Optical fiber

  3. High Performance self-injection locked 524 nm green laser diode for high bitrate visible light communications

    KAUST Repository

    Shamim, Md. Hosne Mobarok; Shemis, Mohamed; Shen, Chao; Oubei, Hassan M.; Ng, Tien Khee; Ooi, Boon S.; Khan, Mohammed Zahed Mustafa

    2018-01-01

    First demonstration of self-injection locking on 524 nm visible laser diode is presented. Enhancement by ~440 MHz (~30%) in modulation bandwidth, ~7 times reduction in lasing linewidth, and ~10 dB improvement in SMSR is achieved.

  4. High Performance self-injection locked 524 nm green laser diode for high bitrate visible light communications

    KAUST Repository

    Shamim, Md. Hosne Mobarok

    2018-03-05

    First demonstration of self-injection locking on 524 nm visible laser diode is presented. Enhancement by ~440 MHz (~30%) in modulation bandwidth, ~7 times reduction in lasing linewidth, and ~10 dB improvement in SMSR is achieved.

  5. Intracavity Cr3+:LiCAF + PPSLT optical parametric oscillator with self-injection-locked pump wave

    International Nuclear Information System (INIS)

    Maestre, H; Torregrosa, A J; Capmany, J

    2013-01-01

    In this letter we present an intracavity pumped continuous wave (CW) doubly resonant optical parametric oscillator (OPO) based on Cr 3+ :LiCaAlF 6 (Cr:LiCAF) as the material generating the OPO pump wave and periodically poled stoichiometric lithium tantalate (PPSLT) as the nonlinear material. The OPO pump wave is spectrally narrowed and tuned by means of an external cavity, thus allowing self-injection locking of the OPO pump wavelength. When operated near degeneracy, the constructed OPO enables a fast tuning of the parametrically generated wavelengths in response to small perturbations of the phase-matching condition. The Cr:LiCAF emission band is especially well suited to provide dual-wavelength oscillation in the optical communications 1550 nm band as a result of the parametric oscillation in PPSLT. (letter)

  6. Investigation of Self-injection Locked Visible Laser Diodes for High Bit-rate Visible Light Communication

    KAUST Repository

    Shamim, Md. Hosne Mobarok; Shemis, Mohamed; Shen, Chao; Oubei, Hassan M.; Ng, Tien Khee; Ooi, Boon S.; Khan, Mohammed Zahed Mustafa

    2018-01-01

    -mode-suppression-ratio was considerably increased in all the cases, reaching as high as ~20 dB in self-injection locked blue laser diode, thus enabling a close to single mode operation. This work paves the way for attaining high speed optical wireless communications by overcoming

  7. Comparative study of diode-pumping self-injection and injection-locking Tm:YAG lasers

    International Nuclear Information System (INIS)

    Wu, C T; Chen, F; Ju, Y L; Wang, Y Z

    2013-01-01

    A comparative study of the laser characteristics of self-injection and injection-locking Tm:YAG lasers is given in this paper. At a pump energy of 145 mJ and Q-switched repetition rate of 100 Hz, an output energy of 2.39 mJ was obtained for an injection-locking Tm:YAG laser, with a pulse width of 403.2 ns and a pulse building-up time of 2.12 μs. Under the same conditions, the output energy, pulse width and pulse build-up time for a self-injection Tm:YAG laser were 2.21 mJ, 407.0 ns and 3.95 μs, respectively. The threshold of the Q-switched injection-locking Tm:YAG laser was much lower than that of the self-injection laser, and the pulse width was narrower and the pulse build-up time shorter. Additionally, the output spectrum was much purer for the injection-locking laser. (paper)

  8. Single-mode Brillouin fiber laser passively stabilized at resonance frequency with self-injection locked pump laser

    International Nuclear Information System (INIS)

    Spirin, V V; Lopez-Mercado, C A; Megret, P; Fotiadi, A A

    2012-01-01

    We demonstrate a single-mode Brillouin fiber ring laser, which is passively stabilized at pump resonance frequency by using self-injection locking of semiconductor pump laser. Resonance condition for Stokes radiation is achieved by length fitting of Brillouin laser cavity. The laser generate single-frequency Stokes wave with linewidth less than 0.5 kHz using approximately 17-m length cavity

  9. Optical self-injection mode-locking of semiconductor optical amplifier fiber ring with electro-absorption modulation—fundamentals and applications

    International Nuclear Information System (INIS)

    Chi, Yu-Chieh; Lin, Gong-Ru

    2013-01-01

    The optical self-injection mode-locking of a semiconductor optical amplifier incorporated fiber ring laser (SOAFL) with spectrally sliced multi-channel carriers is demonstrated for applications. The synthesizer-free SOAFL pulse-train is delivered by optical injection mode-locking with a 10 GHz self-pulsed electro-absorption modulator (EAM). Such a coupled optical and electronic resonator architecture facilitates a self-feedback oscillation with a higher Q-factor and lower phase/intensity noises when compared with conventional approaches. The theoretical model of such an injection-mode-locking SOAFL is derived to improve the self-pulsating performance of the optical return-to-zero (RZ) carrier, thus providing optimized pulsewidth, pulse extinction ratio, effective Q-factor, frequency variation and timing jitter of 11.4 ps, 9.1 dB, 4 × 10 5 , −1 bi-directional WDM transmission network with down-stream RZ binary phase-shift keying (RZ-BPSK) and up-stream re-modulated RZ on–off-keying (RZ-OOK) formats. Under BPSK/OOK bi-directional data transmission, the self-pulsed harmonic mode-locking SOAFL simultaneously provides four to six WDM channels for down-stream RZ-BPSK and up-stream RZ-OOK formats with receiving sensitivities of −17 and −15.2 dBm at a bit error rate of 10 −9 , respectively. (paper)

  10. Advances phase-lock techniques

    CERN Document Server

    Crawford, James A

    2008-01-01

    From cellphones to micrprocessors, to GPS navigation, phase-lock techniques are utilized in most all modern electronic devices. This high-level book takes a systems-level perspective, rather than circuit-level, which differentiates it from other books in the field.

  11. Phase-locked Josephson soliton oscillators

    DEFF Research Database (Denmark)

    Holst, T.; Hansen, Jørn Bindslev; Grønbech-Jensen, N.

    1991-01-01

    Detailed experimental characterization of the phase-locking at both DC and at microwave frequencies is presented for two closely spaced Josephson soliton (fluxon) oscillators. In the phase-locked state, the radiated microwave power exhibited an effective gain. With one common bias source......, a frequency tunability of the phase-locked oscillators up to 7% at 10 GHz was observed. The interacting soliton oscillators were modeled by two inductively coupled nonlinear transmission lines...

  12. Phase locking between Josephson soliton oscillators

    DEFF Research Database (Denmark)

    Holst, T.; Hansen, Jørn Bindslev; Grønbech-Jensen, N.

    1990-01-01

    We report observations of phase-locking phenomena between two Josephson soliton (fluxon) oscillators biased in self-resonant modes. The locking strength was measured as a function of bias conditions. A frequency tunability of the phase-locked oscillators up to 7% at 10 GHz was observed. Two coupled...... perturbed sine-Gordon equations were derived from an equivalent circuit consisting of inductively coupled, nonlinear, lossy transmission lines. These equations were solved numerically to find the locking regions. Good qualitative agreement was found between the experimental results and the calculations...

  13. QPSK regeneration without active phase-locking

    DEFF Research Database (Denmark)

    Kjøller, Niels-Kristian; Da Ros, Francesco; Røge, Kasper Meldgaard

    2016-01-01

    QPSK regeneration without active phase stabilization is investigated in numerical simulations. We propose an improved scheme for phase-locking free QPSK regeneration showing significant improvements in the error vector magnitude of the signal.......QPSK regeneration without active phase stabilization is investigated in numerical simulations. We propose an improved scheme for phase-locking free QPSK regeneration showing significant improvements in the error vector magnitude of the signal....

  14. Weak-light phase locking for LISA

    International Nuclear Information System (INIS)

    McNamara, Paul W

    2005-01-01

    The long armlengths of the LISA interferometer, and the finite aperture of the telescope, lead to an optical power attenuation of ∼10 -10 of the transmitted to received light. Simple reflection at the end of the arm is therefore not an optimum interferometric design. Instead, a local laser is offset phase locked to the weak incoming beam, transferring the phase information of the incoming to the outgoing light. This paper reports on an experiment to characterize a weak-light phase-locking scheme suitable for LISA in which a diode-pumped, Nd:YAG, non-planar ring oscillator (NPRO) is offset phase locked to a low-power (13 pW) frequency stabilized master NPRO. Preliminary results of the relative phase noise of the slave laser shows shot noise limited performance above 0.4 Hz. Excess noise is observed at lower frequencies, most probably due to thermal effects in the optical arrangement and phase-sensing electronics

  15. CMOS switched current phase-locked loop

    NARCIS (Netherlands)

    Leenaerts, D.M.W.; Persoon, G.G.; Putter, B.M.

    1997-01-01

    The authors present an integrated circuit realisation of a switched current phase-locked loop (PLL) in standard 2.4 µm CMOS technology. The centre frequency is tunable to 1 MHz at a clock frequency of 5.46 MHz. The PLL has a measured maximum phase error of 21 degrees. The chip consumes

  16. SWITCHED REFERENCE PHASE LOCK LOOP (SRPLL)

    International Nuclear Information System (INIS)

    KERNER, T.

    2001-01-01

    The Brookhaven National Laboratory Relativistic Heavy Ion Collider (RHIC) has two beam synchronous event links (BSL), one for each ring, which use the 28 MHz ring low level rf to distribute event codes synchronously with a precise phase relationship to the beam. During a cogging reset just before injection, the low level rf sine wave is interrupted which causes the BSL receivers to lose lock. Lock loss in turn causes false triggers and other undesirable-effects on the beam position monitors (BPM), ionization profile monitors (IPM), the tune meter and various experiments which use the BSLs. To rectify these problems, a SRPLL has been inserted between the beam synchronous master and the low level rf source. The SRPLL inserts a frequency and phase continuous splice over the dead-band gap in the rf source created during a cogging reset. The splice removes the gap and prevents the distributed BSL receivers from losing lock

  17. Phase locking of optically coupled lasers

    International Nuclear Information System (INIS)

    Glova, A F

    2003-01-01

    A review of studies of the properties of radiation from optically coupled lasers is presented. The methods for phase locking the fields in optically coupled lasers of different types are considered and the methods for supermode selection and correction of the radiation pattern are discussed. (review)

  18. Computation of the lock-in ranges of phase-locked loops with PI filter

    OpenAIRE

    Aleksandrov, Konstantin D.; Kuznetsov, Nikolay; Leonov, Gennady A.; Neittaanmäki, Pekka; Yuldashev, Marat V.; Yuldashev, Renat V.

    2016-01-01

    In the present work the lock-in range of PLL-based circuits with proportionallyintegrating filter and sinusoidal phase-detector characteristics are studied. Considered circuits have sinusoidal phase detector characteristics. Analytical approach based on the methods of phase plane analysis is applied to estimate the lock-in ranges of the circuits under consideration. Obtained analytical results are compared with simulation results.

  19. Automatic NMR field-frequency lock-pulsed phase locked loop approach.

    Science.gov (United States)

    Kan, S; Gonord, P; Fan, M; Sauzade, M; Courtieu, J

    1978-06-01

    A self-contained deuterium frequency-field lock scheme for a high-resolution NMR spectrometer is described. It is based on phase locked loop techniques in which the free induction decay signal behaves as a voltage-controlled oscillator. By pulsing the spins at an offset frequency of a few hundred hertz and using a digital phase-frequency discriminator this method not only eliminates the usual phase, rf power, offset adjustments needed in conventional lock systems but also possesses the automatic pull-in characteristics that dispense with the use of field sweeps to locate the NMR line prior to closure of the lock loop.

  20. Advanced frequency synthesis by phase lock

    CERN Document Server

    Egan, William F

    2011-01-01

    "An addendum to the popular Frequency Synthesis by Phase Lock, 2nd ed, this book describes sigma-delta, a frequency synthesis technique that has gained prominence in recent years. In addition, Simulink will be employed extensively to guide the reader. Fractional-n, the still-used forerunner to sigma-delta, is also discussed. Sequences of simulated results allow the reader to gain a deeper understanding while detailed appendices provide information from various stages of development. Simulation models discussed in the chapters that are available online."--Provided by publisher.

  1. Reconfigurable Braille display with phase change locking

    Science.gov (United States)

    Soule, Cody W.; Lazarus, Nathan

    2016-07-01

    Automatically updated signs and displays for sighted people are common in today’s world. However, there is no cheap, low power equivalent available for the blind. This work demonstrates a reconfigurable Braille cell using the solid-to-liquid phase change of a low melting point alloy as a zero holding power locking mechanism. The device is actuated with the alloy in the liquid state, and is then allowed to solidify to lock the Braille dot in the actuated position. A low-cost manufacturing process is developed that includes molding of a rigid silicone to create pneumatic channels, and bonding of a thin membrane of a softer silicone on the surface for actuation. A plug of Field’s metal (melting point 62 °C) is placed in the pneumatic channels below each Braille dot to create the final device. The device is well suited for low duty cycle operation in applications such as signs, and is able to maintain its state indefinitely without additional power input. The display requires a pneumatic pressure of only 24 kPa for actuation, and reconfiguration has been demonstrated in less than a minute and a half.

  2. Phase-locking regimes of photonic crystal nanocavity laser arrays

    DEFF Research Database (Denmark)

    Skovgård, Troels Suhr; Kristensen, Philip Trøst; Mørk, Jesper

    2011-01-01

    -difference time-domain calculations, the typical coupling strength is extracted for realistic structures. Phase-locking regimes are identified, and their stability with respect to parameter variation is investigated. The results suggest that quantum well devices are not well suited for phase-locked nanocavity...

  3. Phase locking of vortex cores in two coupled magnetic nanopillars

    Directory of Open Access Journals (Sweden)

    Qiyuan Zhu

    2014-11-01

    Full Text Available Phase locking dynamics of the coupled vortex cores in two identical magnetic spin valves induced by spin-polarized current are studied by means of micromagnetic simulations. Our results show that the available current range of phase locking can be expanded significantly by the use of constrained polarizer, and the vortices undergo large orbit motions outside the polarization areas. The effects of polarization areas and dipolar interaction on the phase locking dynamics are studied systematically. Phase locking parameters extracted from simulations are discussed by theoreticians. The dynamics of vortices influenced by spin valve geometry and vortex chirality are discussed at last. This work provides deeper insights into the dynamics of phase locking and the results are important for the design of spin-torque nano-oscillators.

  4. Control of photon storage time using phase locking.

    Science.gov (United States)

    Ham, Byoung S

    2010-01-18

    A photon echo storage-time extension protocol is presented by using a phase locking method in a three-level backward propagation scheme, where phase locking serves as a conditional stopper of the rephasing process in conventional two-pulse photon echoes. The backward propagation scheme solves the critical problems of extremely low retrieval efficiency and pi rephasing pulse-caused spontaneous emission noise in photon echo based quantum memories. The physics of the storage time extension lies in the imminent population transfer from the excited state to an auxiliary spin state by a phase locking control pulse. We numerically demonstrate that the storage time is lengthened by spin dephasing time.

  5. Experimental implementation of phase locking in a nonlinear interferometer

    Energy Technology Data Exchange (ETDEWEB)

    Wang, Hailong; Jing, Jietai, E-mail: jtjing@phy.ecnu.edu.cn [State Key Laboratory of Precision Spectroscopy, Department of Physics, East China Normal University, Shanghai 200062 (China); Marino, A. M. [Homer L. Dodge Department of Physics and Astronomy, The University of Oklahoma, 440 West Brooks Street, Norman, Oklahoma 73019 (United States)

    2015-09-21

    Based upon two cascade four-wave mixing processes in two identical hot rubidium vapor cells, a nonlinear interferometer has been experimentally realized [Jing et al., Appl. Phys. Lett. 99, 011110 (2011); Hudelist et al., Nat. Commun. 5, 3049 (2014)]. It has a higher degree of phase sensitivity than a traditional linear interferometer and has many potential applications in quantum metrology. Phase locking of the nonlinear interferometer is needed before it can find its way into applications. In this letter, we investigate the experimental implementation of phase locking of the relative phase between the three beams at different frequencies involved in such a nonlinear interferometer. We have utilized two different methods, namely, beat note locking and coherent modulation locking. We find that coherent modulation locking can achieve much better phase stability than beat note locking in our system. Our results pave the way for real applications of a nonlinear interferometer in precision measurement and quantum manipulation, for example, phase control in phase-sensitive N-wave mixing process, N-port nonlinear interferometer and quantum-enhanced real-time phase tracking.

  6. Stable CW Single Frequency Operation of Fabry-Perot Laser Diodes by Self-Injection Phase Locking

    Science.gov (United States)

    Duerksen, Gary L.; Krainak, Michael A.

    1999-01-01

    Previously, single-frequency semiconductor laser operation using fiber Bragg gratings has been achieved by tWo methods: 1) use of the FBG as the output coupler for an anti-reflection-coated semiconductor gain element'; 2) pulsed operation of a gain-switched Fabry-Perot laser diode with FBG-optical and RF-electrical feedback'. Here, we demonstrate CW single frequency operation from a non-AR coated Fabry-Perot laser diode using only FBG optical feedback.

  7. Stable CW Single-Frequency Operation of Fabry-Perot Laser Diodes by Self-Injection Phase Locking

    Science.gov (United States)

    Duerksen, Gary L.; Krainak, Michael A.

    1999-01-01

    Previously, single-frequency semiconductor laser operation using fiber Bragg gratings has been achieved by two methods: 1) use of the FBG as the output coupler for an anti-reflection-coated semiconductor gain element'; 2) pulsed operation of a gain-switched Fabry-Perot laser diode with FBG-optical and RF-electrical feedback. Here, we demonstrate CW single frequency operation from a non-AR coated Fabry-Perot laser diode using only FBG optical feedback. We coupled a nominal 935 run-wavelength Fabry-Perot laser diode to an ultra narrow band (18 pm) FBG. When tuned by varying its temperature, the laser wavelength is pulled toward the centerline of the Bragg grating, and the spectrum of the laser output is seen to fall into three discrete stability regimes as measured by the side-mode suppression ratio.

  8. Development of Phase Lock Loop System for Synchronisation of a ...

    African Journals Online (AJOL)

    Akorede

    KEYWORDS: Phase locked loop (PLL), grid synchronisation, simulations, PI regulator, hybrid system. .... system. AC. - D. C co nv erter. DC-DC converter. DC. - AC co nverter. Load ... The box named Discrete Transfer Fcn is the PI-regulator.

  9. Enforced Electrical Neutrality of the Color-Flavor Locked Phase

    International Nuclear Information System (INIS)

    Rajagopal, Krishna; Wilczek, Frank

    2001-01-01

    We demonstrate that quark matter in the color-flavor locked phase of QCD is rigorously electrically neutral, despite the unequal quark masses, and even in the presence of an electron chemical potential. As long as the strange quark mass and the electron chemical potential do not preclude the color-flavor locked phase, quark matter is automatically neutral. No electrons are required and none are admitted

  10. Development of phase lock loop system for synchronisation of a ...

    African Journals Online (AJOL)

    Phase locked loop (PLL) is an important part of the control unit of the grid connected power converter. The method of zero crossing detection (ZCD) does not produce accurate phase information when grid is non-ideal. In this work, a synchronous reference frame (SRF) PLL method to obtain accurate phase information when ...

  11. Cyclotomy and Ramanujan sums in quantum phase locking

    International Nuclear Information System (INIS)

    Planat, Michel; Rosu, Haret C.

    2003-01-01

    Phase-locking governs the phase noise in classical clocks through effects described in precise mathematical terms. We seek here a quantum counterpart of these effects by working in a finite Hilbert space. We use a coprimality condition to define phase-locked quantum states and the corresponding Pegg-Barnett type phase operator. Cyclotomic symmetries in matrix elements are revealed and related to Ramanujan sums in the theory of prime numbers. The employed mathematical procedures also emphasize the isomorphism between algebraic number theory and the theory of quantum entanglement

  12. Mutual phase-locking of planar nano-oscillators

    Directory of Open Access Journals (Sweden)

    K. Y. Xu

    2014-06-01

    Full Text Available Characteristics of phase-locking between Gunn effect-based planar nano-oscillators are studied using an ensemble Monte Carlo (EMC method. Directly connecting two oscillators in close proximity, e.g. with a channel distance of 200 nm, only results in incoherent oscillations. In order to achieve in-phase oscillations, additional considerations must be taken into account. Two coupling paths are shown to exist between oscillators. One coupling path results in synchronization and the other results in anti-phase locking. The coupling strength through these two paths can be adjusted by changing the connections between oscillators. When two identical oscillators are in the anti-phase locking regime, fundamental components of oscillations are cancelled. The resulting output consists of purely second harmonic oscillations with a frequency of about 0.66 THz. This type of second harmonic generation is desired for higher frequency applications since no additional filter system is required. This transient phase-locking process is further analyzed using Adler's theory. The locking range is extracted, and a criterion for the channel length difference required for realizing phased arrays is obtained. This work should aid in designing nano-oscillator arrays for high power applications and developing directional transmitters for wireless communications.

  13. Automatic carrier acquisition system for phase-lock-loop receivers

    Science.gov (United States)

    Bunce, R. C.

    1973-01-01

    Programmable oscillator and zero-beat detector acquires phase-lock of carrier by frequency scanning. Generation of high-level dc pulse at instant of zero crossing provides positive trigger for decision gate to stop search and close loop for phase-coherent tracking.

  14. Sampling phase lock loop (PLL) with low power clock buffer

    NARCIS (Netherlands)

    Gao, X.; Bahai, A.; Bohsali, M.; Djabbari, A.; Klumperink, Eric A.M.; Nauta, Bram; Socci, G.

    2013-01-01

    A sampling phase locked loop (PLL) circuit includes a pull-up/down buffer configured to convert an oscillator reference clock into a square wave sampling control signal input to a sampling phase detector. The buffer circuit is configured to reduce power by controlling the switching of the pull-up

  15. Phase Locking a Clock Oscillator to a Coherent Atomic Ensemble

    Directory of Open Access Journals (Sweden)

    R. Kohlhaas

    2015-04-01

    Full Text Available The sensitivity of an atomic interferometer increases when the phase evolution of its quantum superposition state is measured over a longer interrogation interval. In practice, a limit is set by the measurement process, which returns not the phase but its projection in terms of population difference on two energetic levels. The phase interval over which the relation can be inverted is thus limited to the interval [-π/2,π/2]; going beyond it introduces an ambiguity in the readout, hence a sensitivity loss. Here, we extend the unambiguous interval to probe the phase evolution of an atomic ensemble using coherence-preserving measurements and phase corrections, and demonstrate the phase lock of the clock oscillator to an atomic superposition state. We propose a protocol based on the phase lock to improve atomic clocks limited by local oscillator noise, and foresee the application to other atomic interferometers such as inertial sensors.

  16. Phase-locked flux-flow Josephson oscillator

    DEFF Research Database (Denmark)

    Ustinov, A. V.; Mygind, Jesper; Oboznov, V. A.

    1992-01-01

    We report on the observation of large rf induced steps due to phase-locking of unidirectional flux-flow motion in long quasi-one-dimensional Josephson junctions. The external microwave irradiation in the frequency range 62–77 GHz was applied from the edge of the junction at which the fluxons enter....... The dependence of the amplitude of the phase-locked step on external magnetic field and microwave power has been measured. The observed zero-crossing steps have potential application in Josephson voltage standards. A simple model for the flux-flow as determined by the microwave driven boundary gate at the edge...

  17. Microwave phase locking of Josephson-junction fluxon oscillators

    DEFF Research Database (Denmark)

    Salerno, M.; Samuelsen, Mogens Rugholm; Filatrella, G.

    1990-01-01

    Application of the classic McLaughlin-Scott soliton perturbation theory to a Josephson-junction fluxon subjected to a microwave field that interacts with the fluxon only at the junction boundaries reduces the problem of phase locking of the fluxon oscillation to the study of a two-dimensional fun......Application of the classic McLaughlin-Scott soliton perturbation theory to a Josephson-junction fluxon subjected to a microwave field that interacts with the fluxon only at the junction boundaries reduces the problem of phase locking of the fluxon oscillation to the study of a two...

  18. Relaxation towards phase-locked dynamics in long Josephson junctions

    DEFF Research Database (Denmark)

    Salerno, M.; Grønbech-Jensen, Niels; Samuelsen, Mogens Rugholm

    1995-01-01

    We study the relaxation phenomenon towards phase-locked dynamics in long Josephson junctions. In particular the dependence of the relaxation frequency for the equal time of flight solution on the junction parameters is derived. The analysis is based on a phase-locked map and is compared with direct...... numerical experiments performed both on the map and on the perturbed sine-Gordon equation. As an interesting result we find that very close to a bifurcation the relaxation frequency is exactly equal to the half of the step frequency, i.e., the frequency characterizing the period-one solution....

  19. Short locking time and low jitter phase-locked loop based on slope charge pump control

    International Nuclear Information System (INIS)

    Guo Zhongjie; Liu Youbao; Wu Longsheng; Wang Xihu; Tang Wei

    2010-01-01

    A novel structure of a phase-locked loop (PLL) characterized by a short locking time and low jitter is presented, which is realized by generating a linear slope charge pump current dependent on monitoring the output of the phase frequency detector (PFD) to implement adaptive bandwidth control. This improved PLL is created by utilizing a fast start-up circuit and a slope current control on a conventional charge pump PLL. First, the fast start-up circuit is enabled to achieve fast pre-charging to the loop filter. Then, when the output pulse of the PFD is larger than a minimum value, the charge pump current is increased linearly by the slope current control to ensure a shorter locking time and a lower jitter. Additionally, temperature variation is attenuated with the temperature compensation in the charge pump current design. The proposed PLL has been fabricated in a kind of DSP chip based on a 0.35 μm CMOS process. Comparing the characteristics with the classical PLL, the proposed PLL shows that it can reduce the locking time by 60% with a low peak-to-peak jitter of 0.3% at a wide operation temperature range. (semiconductor integrated circuits)

  20. Foundry fabricated photonic integrated circuit optical phase lock loop.

    Science.gov (United States)

    Bałakier, Katarzyna; Fice, Martyn J; Ponnampalam, Lalitha; Graham, Chris S; Wonfor, Adrian; Seeds, Alwyn J; Renaud, Cyril C

    2017-07-24

    This paper describes the first foundry-based InP photonic integrated circuit (PIC) designed to work within a heterodyne optical phase locked loop (OPLL). The PIC and an external electronic circuit were used to phase-lock a single-line semiconductor laser diode to an incoming reference laser, with tuneable frequency offset from 4 GHz to 12 GHz. The PIC contains 33 active and passive components monolithically integrated on a single chip, fully demonstrating the capability of a generic foundry PIC fabrication model. The electronic part of the OPLL consists of commercially available RF components. This semi-packaged system stabilizes the phase and frequency of the integrated laser so that an absolute frequency, high-purity heterodyne signal can be generated when the OPLL is in operation, with phase noise lower than -100 dBc/Hz at 10 kHz offset from the carrier. This is the lowest phase noise level ever demonstrated by monolithically integrated OPLLs.

  1. Phase and Frequency Locked Magnetrons for SRF Sources

    International Nuclear Information System (INIS)

    Neubauer, M.; Johnson, R.P.; Popovic, M.; Moretti, A.

    2009-01-01

    Magnetrons are low-cost highly-efficient microwave sources, but they have several limitations, primarily centered about the phase and frequency stability of their output. When the stability requirements are low, such as for medical accelerators or kitchen ovens, magnetrons are the very efficient power source of choice. But for high energy accelerators, because of the need for frequency and phase stability - proton accelerators need 1-2 degrees source phase stability, and electron accelerators need .1-.2 degrees of phase stability - they have rarely been used. We describe a novel variable frequency cavity technique which will be utilized to phase and frequency lock magnetrons.

  2. A Quasi-Type-1 Phase-Locked Loop Structure

    DEFF Research Database (Denmark)

    Golestan, Saeed; Fernandez, Francisco Daniel Freijedo; Vidal, Ana

    2014-01-01

    The grid voltage phase and frequency are crucial information in control of most grid connected power electronic based equipment. Most often, a phase-locked loop (PLL) is employed for this purpose. A PLL is a closed-loop feedback control system that the phase of its output signal is related...... to the phase of its input signal. Arguably, the simplest PLL is a type-1 PLL. The type-1 PLLs are characterized by having only one integrator in their control loop and therefore having a high stability margin. However, they suffer from a serious drawback: they cannot achieve zero average steady-state phase...

  3. A novel calibration method for phase-locked loops

    DEFF Research Database (Denmark)

    Cassia, Marco; Shah, Peter Jivan; Bruun, Erik

    2005-01-01

    A novel method to calibrate the frequency response of a Phase-Locked Loop is presented. The method requires just an additional digital counter to measure the natural frequency of the PLL; moreover it is capable of estimating the static phase offset. The measured value can be used to tune the PLL ...... response to the desired value. The method is demonstrated mathematically on a typical PLL topology and it is extended to SigmaDelta fractional-N PLLs. A set of simulations performed with two different simulators is used to verify the applicability of the method.......A novel method to calibrate the frequency response of a Phase-Locked Loop is presented. The method requires just an additional digital counter to measure the natural frequency of the PLL; moreover it is capable of estimating the static phase offset. The measured value can be used to tune the PLL...

  4. A Digital Phase Lock Loop for an External Cavity Diode Laser

    Science.gov (United States)

    Wang, Xiao-Long; Tao, Tian-Jiong; Cheng, Bing; Wu, Bin; Xu, Yun-Fei; Wang, Zhao-Ying; Lin, Qiang

    2011-08-01

    A digital optical phase lock loop (OPLL) is implemented to synchronize the frequency and phase between two external cavity diode lasers (ECDL), generating Raman pulses for atom interferometry. The setup involves all-digital phase detection and a programmable digital proportional-integral-derivative (PID) loop in locking. The lock generates a narrow beat-note linewidth below 1 Hz and low phase-noise of 0.03rad2 between the master and slave ECDLs. The lock proves to be stable and robust, and all the locking parameters can be set and optimized on a computer interface with convenience, making the lock adaptable to various setups of laser systems.

  5. Phase-locked loops. [in analog and digital circuits communication system

    Science.gov (United States)

    Gupta, S. C.

    1975-01-01

    An attempt to systematically outline the work done in the area of phase-locked loops which are now used in modern communication system design is presented. The analog phase-locked loops are well documented in several books but discrete, analog-digital, and digital phase-locked loop work is scattered. Apart from discussing the various analysis, design, and application aspects of phase-locked loops, a number of references are given in the bibliography.

  6. Spikes matter for phase-locked bursting in inhibitory neurons

    Science.gov (United States)

    Jalil, Sajiya; Belykh, Igor; Shilnikov, Andrey

    2012-03-01

    We show that inhibitory networks composed of two endogenously bursting neurons can robustly display several coexistent phase-locked states in addition to stable antiphase and in-phase bursting. This work complements and enhances our recent result [Jalil, Belykh, and Shilnikov, Phys. Rev. EPLEEE81539-375510.1103/PhysRevE.81.045201 81, 045201(R) (2010)] that fast reciprocal inhibition can synchronize bursting neurons due to spike interactions. We reveal the role of spikes in generating multiple phase-locked states and demonstrate that this multistability is generic by analyzing diverse models of bursting networks with various fast inhibitory synapses; the individual cell models include the reduced leech heart interneuron, the Sherman model for pancreatic beta cells, and the Purkinje neuron model.

  7. Phase lock of rapid cycling synchrotron and neutron choppers

    International Nuclear Information System (INIS)

    Praeg, W.; McGhee, D.; Volk, G.

    1981-01-01

    The 500-MeV synchrotron of Argonne's Intense Pulsed Neutron Source operates at 30 Hz. Its beam spill must be locked to neutron choppers with a precision of +- 0.5 μs. A chopper and an accelerator have large and different inertias. This makes synchronization by phase lock to the 60-Hz power line extremely difficult. We solved the phasing problems by running both the Ring Magnet Power Supply (RMPS) of the synchrotron and the chopper motors from a common oscillator that is stable to 1 ppM and by controlling five quantities of the RMPS. The quantities controlled by feedback loops are dc current, injection current, ejection current, resonant frequency, and the phase shift between the synchrotron peak field and the chopper window

  8. Phase noise reduction by self-phase locking in semiconductor lasers using phase conjugate feedback

    DEFF Research Database (Denmark)

    Petersen, Lykke; Gliese, Ulrik Bo; Nielsen, Torben Nørskov

    1994-01-01

    noise takes a finite-low value corresponding to a state of first-order self-phase locking of the laser. As a result, the spectral shape of the laser signal does not remain Lorentzian but collapses around the carrier to a delta function with a close to carrier noise level of less than -137 d...

  9. A Novel Phase-Locking-Free Phase Sensitive Amplifier based Regenerator

    DEFF Research Database (Denmark)

    Kjøller, Niels-Kristian; Røge, Kasper Meldgaard; Guan, Pengyu

    2016-01-01

    We propose a scheme for phase regeneration of optical binary phase-shift keying (BPSK) data signals based on phase sensitive amplification without active phase-locking. A delay interferometer (DI) is used to convert a BPSK signal impaired by noise to an amplitude modulated signal followed by cross......-locked pumps. As a result, active phase-stabilization is avoided. A proof-of-principle experiment is carried out with a dual-pump degenerate phase sensitive amplifier (PSA), demonstrating regeneration for a 10 Gb/s non-return-to-zero differential BPSK (NRZ-DPSK) data signal degraded by a sinusoidal phase...

  10. Phase-locking transition in a chirped superconducting Josephson resonator.

    Science.gov (United States)

    Naaman, O; Aumentado, J; Friedland, L; Wurtele, J S; Siddiqi, I

    2008-09-12

    We observe a sharp threshold for dynamic phase locking in a high-Q transmission line resonator embedded with a Josephson tunnel junction, and driven with a purely ac, chirped microwave signal. When the drive amplitude is below a critical value, which depends on the chirp rate and is sensitive to the junction critical current I0, the resonator is only excited near its linear resonance frequency. For a larger amplitude, the resonator phase locks to the chirped drive and its amplitude grows until a deterministic maximum is reached. Near threshold, the oscillator evolves smoothly in one of two diverging trajectories, providing a way to discriminate small changes in I0 with a nonswitching detector, with potential applications in quantum state measurement.

  11. Gamma power is phase-locked to posterior alpha activity.

    Directory of Open Access Journals (Sweden)

    Daria Osipova

    Full Text Available Neuronal oscillations in various frequency bands have been reported in numerous studies in both humans and animals. While it is obvious that these oscillations play an important role in cognitive processing, it remains unclear how oscillations in various frequency bands interact. In this study we have investigated phase to power locking in MEG activity of healthy human subjects at rest with their eyes closed. To examine cross-frequency coupling, we have computed coherence between the time course of the power in a given frequency band and the signal itself within every channel. The time-course of the power was calculated using a sliding tapered time window followed by a Fourier transform. Our findings show that high-frequency gamma power (30-70 Hz is phase-locked to alpha oscillations (8-13 Hz in the ongoing MEG signals. The topography of the coupling was similar to the topography of the alpha power and was strongest over occipital areas. Interestingly, gamma activity per se was not evident in the power spectra and only became detectable when studied in relation to the alpha phase. Intracranial data from an epileptic subject confirmed these findings albeit there was slowing in both the alpha and gamma band. A tentative explanation for this phenomenon is that the visual system is inhibited during most of the alpha cycle whereas a burst of gamma activity at a specific alpha phase (e.g. at troughs reflects a window of excitability.

  12. Evaluating the Gapless Color-Flavor Locked Phase

    DEFF Research Database (Denmark)

    Alford, Mark; Kouvaris, Christoforos; Rajagopal, Krishna

    2004-01-01

    In neutral cold quark matter that is sufficiently dense that the strange quark mass M_s is unimportant, all nine quarks (three colors; three flavors) pair in a color-flavor locked (CFL) pattern, and all fermionic quasiparticles have a gap. We recently argued that the next phase down in density (as...... a function of decreasing quark chemical potential mu or increasing strange quark mass M_s) is the new ``gapless CFL'' (``gCFL'') phase in which only seven quasiparticles have a gap, while there are gapless quasiparticles described by two dispersion relations at three momenta. There is a continuous quantum...... phase transition from CFL to gCFL quark matter at M_s^2/mu approximately equal to 2*Delta, with Delta the gap parameter. Gapless CFL, like CFL, leaves unbroken a linear combination "Q-tilde" of electric and color charges, but it is a Q-tilde-conductor with gapless Q-tilde-charged quasiparticles...

  13. DECIPHERING THERMAL PHASE CURVES OF DRY, TIDALLY LOCKED TERRESTRIAL PLANETS

    Energy Technology Data Exchange (ETDEWEB)

    Koll, Daniel D. B.; Abbot, Dorian S., E-mail: dkoll@uchicago.edu [Department of the Geophysical Sciences, University of Chicago, Chicago, IL 60637 (United States)

    2015-03-20

    Next-generation space telescopes will allow us to characterize terrestrial exoplanets. To do so effectively it will be crucial to make use of all available data. We investigate which atmospheric properties can, and cannot, be inferred from the broadband thermal phase curve of a dry and tidally locked terrestrial planet. First, we use dimensional analysis to show that phase curves are controlled by six nondimensional parameters. Second, we use an idealized general circulation model to explore the relative sensitivity of phase curves to these parameters. We find that the feature of phase curves most sensitive to atmospheric parameters is the peak-to-trough amplitude. Moreover, except for hot and rapidly rotating planets, the phase amplitude is primarily sensitive to only two nondimensional parameters: (1) the ratio of dynamical to radiative timescales and (2) the longwave optical depth at the surface. As an application of this technique, we show how phase curve measurements can be combined with transit or emission spectroscopy to yield a new constraint for the surface pressure and atmospheric mass of terrestrial planets. We estimate that a single broadband phase curve, measured over half an orbit with the James Webb Space Telescope, could meaningfully constrain the atmospheric mass of a nearby super-Earth. Such constraints will be important for studying the atmospheric evolution of terrestrial exoplanets as well as characterizing the surface conditions on potentially habitable planets.

  14. Phase-locking of driven vortex lattices with transverse ac force and periodic pinning

    International Nuclear Information System (INIS)

    Reichhardt, Charles; Kolton, Alejandro B.; Dominguez, Daniel; Gronbech-Jensen, Niels

    2001-01-01

    For a vortex lattice moving in a periodic array we show analytically and numerically that a new type of phase locking occurs in the presence of a longitudinal dc driving force and a transverse ac driving force. This phase locking is distinct from the Shapiro step phase locking found with longitudinal ac drives. We show that an increase in critical current and a fundamental phase-locked step width scale with the square of the driving ac amplitude. Our results should carry over to other systems such as vortex motion in Josephson-junction arrays

  15. Phase locking and spectral linewidth of a two-mode terahertz quantum cascade laser

    NARCIS (Netherlands)

    Baryshev, A.; Hovenier, J. N.; Adam, A. J. L.; Kašalynas, I.; Gao, J. R.; Klaassen, T. O.; Williams, B. S.; Kumar, S.; Hu, Q.; Reno, J. L.

    2006-01-01

    We have studied the phase locking and spectral linewidth of an ˜2.7THz quantum cascade laser by mixing its two lateral lasing modes. The beat signal at about 8GHz is compared with a microwave reference by applying conventional phase lock loop circuitry with feedback to the laser bias current. Phase

  16. A Digital Phase Lock Loop for an External Cavity Diode Laser

    International Nuclear Information System (INIS)

    Wang Xiao-Long; Tao Tian-Jiong; Cheng Bing; Wu Bin; Xu Yun-Fei; Wang Zhao-Ying; Lin Qiang

    2011-01-01

    A digital optical phase lock loop (OPLL) is implemented to synchronize the frequency and phase between two external cavity diode lasers (ECDL), generating Raman pulses for atom interferometry. The setup involves all-digital phase detection and a programmable digital proportional-integral-derivative (PID) loop in locking. The lock generates a narrow beat-note linewidth below 1 Hz and low phase-noise of 0.03rad 2 between the master and slave ECDLs. The lock proves to be stable and robust, and all the locking parameters can be set and optimized on a computer interface with convenience, making the lock adaptable to various setups of laser systems. (fundamental areas of phenomenology(including applications))

  17. Analog phase lock between two lasers at LISA power levels

    International Nuclear Information System (INIS)

    Diekmann, Christian; Steier, Frank; Sheard, Benjamin; Heinzel, Gerhard; Danzmann, Karsten

    2009-01-01

    This paper presents the implementation of an analog optical phase-locked-loop with an offset frequency of about 20MHz between two lasers, where the detected light powers were of the order of 31 pW and 200 μW. The goal of this setup was the design and characterization of a photodiode transimpedance amplifier for application in LISA. By application of a transimpedance amplifier designed to have low noise and low power consumption, the phase noise between the two lasers was a factor of two above the shot noise limit down to 60mHz. The achievable phase sensitivity depends ultimately on the available power of the highly attenuated master laser and on the input current noise of the transimpedance amplifier of the photodetector. The limiting noise source below 60mHz was the analog phase measurement system that was used in this experiment. A digital phase measurement system that is currently under development at the AEI will be used in the near future. Its application should improve the sensitivity.

  18. Analog phase lock between two lasers at LISA power levels

    Energy Technology Data Exchange (ETDEWEB)

    Diekmann, Christian; Steier, Frank; Sheard, Benjamin; Heinzel, Gerhard; Danzmann, Karsten, E-mail: Christian.Diekmann@aei.mpg.d [Max-Planck-Institute for Gravitational Physics, Callinstr. 38, D-30167 Hannover (Germany)

    2009-03-01

    This paper presents the implementation of an analog optical phase-locked-loop with an offset frequency of about 20MHz between two lasers, where the detected light powers were of the order of 31 pW and 200 muW. The goal of this setup was the design and characterization of a photodiode transimpedance amplifier for application in LISA. By application of a transimpedance amplifier designed to have low noise and low power consumption, the phase noise between the two lasers was a factor of two above the shot noise limit down to 60mHz. The achievable phase sensitivity depends ultimately on the available power of the highly attenuated master laser and on the input current noise of the transimpedance amplifier of the photodetector. The limiting noise source below 60mHz was the analog phase measurement system that was used in this experiment. A digital phase measurement system that is currently under development at the AEI will be used in the near future. Its application should improve the sensitivity.

  19. Ultrafast Phase Comparator for Phase-Locked Loop-Based Optoelectronic Clock Recovery Systems

    DEFF Research Database (Denmark)

    Gomez-Agis, F.; Oxenløwe, Leif Katsuo; Kurimura, S.

    2009-01-01

    The authors report on a novel application of a chi((2)) nonlinear optical device as an ultrafast phase comparator, an essential element that allows an optoelectronic phase-locked loop to perform clock recovery of ultrahigh-speed optical time-division multiplexed (OTDM) signals. Particular interest...... is devoted to a quasi-phase-matching adhered-ridge-waveguide periodically poled lithium niobate (PPLN) device, which shows a sufficient high temporal resolution to resolve a 640 Gbits OTDM signal....

  20. Phase locking and spectral linewidth of a two-mode terahertz quantum cascade laser

    NARCIS (Netherlands)

    Baryshev, A.; Hovenier, J.N.; Adam, A.J.L.; Kašalynas, I.; Gao, J.R.; Klaassen, T.O.; Williams, B.S.; Kumar, S.; Hu, Q.; Reno, J.L.

    2006-01-01

    We have studied the phase locking and spectral linewidth of an ? 2.7?THz quantum cascade laser by mixing its two lateral lasing modes. The beat signal at about 8?GHz is compared with a microwave reference by applying conventional phase lock loop circuitry with feedback to the laser bias current.

  1. Mutual phase-locking of several spin-torque nano-oscillators

    International Nuclear Information System (INIS)

    Prokopenko, O.V.; Sulimenko, O.R.

    2011-01-01

    Criterions for evaluating the effectiveness of mutual phase-locking of several spin-torque nano-oscillators (STNO) are proposed. An application of one of the criterions to describe the process of mutual phase-locking of the three almost identical STNO's is considered

  2. Electron self-injection in the donut bubble wakefield

    Science.gov (United States)

    Firouzjaei, Ali Shekari; Shokri, Babak

    2018-05-01

    We investigate electron self-injection in a donut bubble wakefield driven by a Laguerre-Gauss laser pulse. The present work discusses the electron capture by modeling the analytical donut bubble field. We discuss the self-injection of the electrons from plasma for various initial conditions and then compare the results. We show that the donut bubble can trap plasma electrons forming a hollow beam. We present the phase spaces and longitudinal momentum evolution for the trapped electrons in the bubble and discuss their characteristic behaviors and stability. It will be shown that the electrons self-injected in the front are ideal for applications in which a good stability and low energy spread are essential.

  3. Optimum phase noise reduction and repetition rate tuning in quantum-dot mode-locked lasers

    Energy Technology Data Exchange (ETDEWEB)

    Habruseva, T. [CAPPA, Cork Institute of Technology, Cork (Ireland); Tyndall National Institute, Lee Maltings, Cork (Ireland); Aston University, Aston Triangle, B4 7ET Birmingham (United Kingdom); Arsenijević, D.; Kleinert, M.; Bimberg, D. [Institut für Festkörperphysik, Technische Universität Berlin, Berlin (Germany); Huyet, G.; Hegarty, S. P. [CAPPA, Cork Institute of Technology, Cork (Ireland); Tyndall National Institute, Lee Maltings, Cork (Ireland)

    2014-01-13

    Competing approaches exist, which allow control of phase noise and frequency tuning in mode-locked lasers, but no judgement of pros and cons based on a comparative analysis was presented yet. Here, we compare results of hybrid mode-locking, hybrid mode-locking with optical injection seeding, and sideband optical injection seeding performed on the same quantum dot laser under identical bias conditions. We achieved the lowest integrated jitter of 121 fs and a record large radio-frequency (RF) tuning range of 342 MHz with sideband injection seeding of the passively mode-locked laser. The combination of hybrid mode-locking together with optical injection-locking resulted in 240 fs integrated jitter and a RF tuning range of 167 MHz. Using conventional hybrid mode-locking, the integrated jitter and the RF tuning range were 620 fs and 10 MHz, respectively.

  4. Optimum phase noise reduction and repetition rate tuning in quantum-dot mode-locked lasers

    International Nuclear Information System (INIS)

    Habruseva, T.; Arsenijević, D.; Kleinert, M.; Bimberg, D.; Huyet, G.; Hegarty, S. P.

    2014-01-01

    Competing approaches exist, which allow control of phase noise and frequency tuning in mode-locked lasers, but no judgement of pros and cons based on a comparative analysis was presented yet. Here, we compare results of hybrid mode-locking, hybrid mode-locking with optical injection seeding, and sideband optical injection seeding performed on the same quantum dot laser under identical bias conditions. We achieved the lowest integrated jitter of 121 fs and a record large radio-frequency (RF) tuning range of 342 MHz with sideband injection seeding of the passively mode-locked laser. The combination of hybrid mode-locking together with optical injection-locking resulted in 240 fs integrated jitter and a RF tuning range of 167 MHz. Using conventional hybrid mode-locking, the integrated jitter and the RF tuning range were 620 fs and 10 MHz, respectively

  5. Space-time considerations in the phase locking of high harmonics

    International Nuclear Information System (INIS)

    Gaarde, Mette B.; Schafer, Kenneth J.

    2002-01-01

    The combination of several high order harmonics can produce an attosecond pulse train, provided that the harmonics are locked in phase to each other. We present calculations that evaluate the degree of phase locking that is achieved in argon and neon gases interacting with an intense, 50 fs laser pulse, for a range of macroscopic conditions. We find that phase locking depends on both the temporal and the spatial phase behavior of the harmonics, as determined by the interplay between the intrinsic dipole phase and the phase matching in the nonlinear medium. We show that, as a consequence of this, it is not possible to compensate for a lack of phase locking by purely temporal phase manipulation

  6. Phase and Frequency Locked Magnetrons for SRF Sources

    Energy Technology Data Exchange (ETDEWEB)

    Neubauer, Michael [Muons, Inc.; Johnson, Rolland

    2014-09-12

    There is great potential for a magnetron power source that can be controlled both in phase and frequency. Such a power source could revolutionize many particle accelerator systems that require lower capital cost and/or higher power efficiency. Beyond the accelerator community, phase and frequency locked magnetons could improve radar systems around the world and make affordable phased arrays for wireless power transmission for solar powered satellites. This joint project of Muons, Inc., Fermilab, and L-3 CTL was supported by an STTR grant monitored by the Nuclear Physics Office of the DOE Office of Science. The object of the program was to incorporate ferrite materials into the anode of a magnetron and, with appropriate biasing of the ferrites, to maintain frequency lock and to allow for frequency adjustment of the magnetron without mechanical tuners. If successful, this device would have a dual use both as a source for SRF linacs and for military applications where fast tuning of the frequency is a requirement. In order to place the materials in the proper location, several attributes needed to be modeled. First the impact of the magnetron’s magnetic field needed to be shielded from the ferrites so that they were not saturated. And second, the magnetic field required to change the frequency of the magnetron at the ferrites needed to be shielded from the region containing the circulating electrons. ANSYS calculations of the magnetic field were used to optimize both of these parameters. Once the design for these elements was concluded, parts were fabricated and a complete test assembly built to confirm the predictions of the computer models. The ferrite material was also tested to determine its compatibility with magnetron tube processing temperatures. This required a vacuum bake out of the chosen material to determine the cleanliness of the material in terms of outgassing characteristics, and a subsequent room temperature test to verify that the characteristics of

  7. Mode-locked terahertz quantum cascade laser by direct phase synchronization

    International Nuclear Information System (INIS)

    Maussang, K.; Maysonnave, J.; Jukam, N.; Freeman, J. R.; Cavalié, P.; Dhillon, S. S.; Tignon, J.; Khanna, S. P.; Linfield, E. H.; Davies, A. G.; Beere, H. E.; Ritchie, D. A.

    2013-01-01

    Mode-locking of a terahertz quantum cascade laser is achieved using multimode injection seeding. Contrary to standard methods that rely on gain modulation, here a fixed phase relationship is directly imprinted to the laser modes. In this work, we demonstrate the generation of 9 ps phase mode-locked pulses around 2.75 THz. A direct measurement of the emitted field phase shows that it results from the phase of the initial injection

  8. Phase locking of a semiconductor double-quantum-dot single-atom maser

    Science.gov (United States)

    Liu, Y.-Y.; Hartke, T. R.; Stehlik, J.; Petta, J. R.

    2017-11-01

    We experimentally study the phase stabilization of a semiconductor double-quantum-dot (DQD) single-atom maser by injection locking. A voltage-biased DQD serves as an electrically tunable microwave frequency gain medium. The statistics of the maser output field demonstrate that the maser can be phase locked to an external cavity drive, with a resulting phase noise L =-99 dBc/Hz at a frequency offset of 1.3 MHz. The injection locking range, and the phase of the maser output relative to the injection locking input tone are in good agreement with Adler's theory. Furthermore, the electrically tunable DQD energy level structure allows us to rapidly switch the gain medium on and off, resulting in an emission spectrum that resembles a frequency comb. The free running frequency comb linewidth is ≈8 kHz and can be improved to less than 1 Hz by operating the comb in the injection locked regime.

  9. Phase locking of moving magnetic vortices in bridge-coupled nanodisks

    International Nuclear Information System (INIS)

    Zhu, Qiyuan; Zheng, Qi; Liu, Xianyin; Liu, Qingfang; Wang, Jianbo

    2015-01-01

    In this paper, phase locking dynamics of vortices induced by spin transfer torque in bridge-coupled nanodisks are studied by micromagnetic simulations. In the presence of the bridge coupling, the required time for the phase locking is dramatically reduced, and the phase difference between the two vortices keeps at a nonzero value after the phase locking. Moreover, the phase difference is affected significantly by bridge coupling, Oersted field distribution, nanodisk size, as well as in-plane bias magnetic field. In addition, the coupled gyrotropic frequency of vortices depends linearly on the perpendicular magnetic field. This systematic study of phase locking parameters, especially the phase difference, is important for the applications of vortex-based spin-torque nano-oscillators

  10. Phase locking of moving magnetic vortices in bridge-coupled nanodisks

    Energy Technology Data Exchange (ETDEWEB)

    Zhu, Qiyuan; Zheng, Qi; Liu, Xianyin; Liu, Qingfang, E-mail: liuqf@lzu.edu.cn [Key Laboratory for Magnetism and Magnetic Materials of the Ministry of Education, Lanzhou University, Lanzhou 730000 (China); Wang, Jianbo [Key Laboratory for Magnetism and Magnetic Materials of the Ministry of Education, Lanzhou University, Lanzhou 730000 (China); Key Laboratory of Special Function Materials and Structure Design, Ministry of Education, Lanzhou University, Lanzhou 730000 (China)

    2015-05-07

    In this paper, phase locking dynamics of vortices induced by spin transfer torque in bridge-coupled nanodisks are studied by micromagnetic simulations. In the presence of the bridge coupling, the required time for the phase locking is dramatically reduced, and the phase difference between the two vortices keeps at a nonzero value after the phase locking. Moreover, the phase difference is affected significantly by bridge coupling, Oersted field distribution, nanodisk size, as well as in-plane bias magnetic field. In addition, the coupled gyrotropic frequency of vortices depends linearly on the perpendicular magnetic field. This systematic study of phase locking parameters, especially the phase difference, is important for the applications of vortex-based spin-torque nano-oscillators.

  11. Phase locking and quantum statistics in a parametrically driven nonlinear resonator

    OpenAIRE

    Hovsepyan, G. H.; Shahinyan, A. R.; Chew, Lock Yue; Kryuchkyan, G. Yu.

    2016-01-01

    We discuss phase-locking phenomena at low-level of quanta for parametrically driven nonlinear Kerr resonator (PDNR) in strong quantum regime. Oscillatory mode of PDNR is created in the process of a degenerate down-conversion of photons under interaction with a train of external Gaussian pulses. We calculate the Wigner functions of cavity mode showing two-fold symmetry in phase space and analyse formation of phase-locked states in the regular as well as the quantum chaotic regime.

  12. A digital closed loop control system for automatic phase locking of superconducting cavities of IUAC Linac

    International Nuclear Information System (INIS)

    Dutt, R.N.; Rai, A.; Pandey, A.; Sahu, B.K.; Patra, P.; Karmakar, J.; Chaudhari, G.K.; Mathur, Y.; Ghosh, S.; Kanjilal, D.

    2013-01-01

    A closed loop digital control system has been designed and tested to automate the tuning process of superconducting resonators of LINAC at Inter-University Accelerator Centre, New Delhi. The mechanism controls the proportional valves of the He gas based pneumatic tuner in response to the phase and frequency errors of the cavity RF field. The main RF phase lock loop (PLL) is automatically closed once the resonant frequency is within locking range of the resonator PLL. The digital control scheme was successfully tested on few resonators of LINAC cryostat 1. A high stability of phase lock was observed. The details of the digital automation system are presented in the paper. (author)

  13. Phase-locked patterns of the Kuramoto model on 3-regular graphs

    Science.gov (United States)

    DeVille, Lee; Ermentrout, Bard

    2016-09-01

    We consider the existence of non-synchronized fixed points to the Kuramoto model defined on sparse networks: specifically, networks where each vertex has degree exactly three. We show that "most" such networks support multiple attracting phase-locked solutions that are not synchronized and study the depth and width of the basins of attraction of these phase-locked solutions. We also show that it is common in "large enough" graphs to find phase-locked solutions where one or more of the links have angle difference greater than π/2.

  14. Wavelet brain angiography suggests arteriovenous pulse wave phase locking.

    Directory of Open Access Journals (Sweden)

    William E Butler

    Full Text Available When a stroke volume of arterial blood arrives to the brain, the total blood volume in the bony cranium must remain constant as the proportions of arterial and venous blood vary, and by the end of the cardiac cycle an equivalent volume of venous blood must have been ejected. I hypothesize the brain to support this process by an extraluminally mediated exchange of information between its arterial and venous circulations. To test this I introduce wavelet angiography methods to resolve single moving vascular pulse waves (PWs in the brain while simultaneously measuring brain pulse motion. The wavelet methods require angiographic data acquired at significantly faster rate than cardiac frequency. I obtained these data in humans from brain surface optical angiograms at craniotomy and in piglets from ultrasound angiograms via cranial window. I exploit angiographic time of flight to resolve arterial from venous circulation. Initial wavelet reconstruction proved unsatisfactory because of angiographic motion alias from brain pulse motion. Testing with numerically simulated cerebral angiograms enabled the development of a vascular PW cine imaging method based on cross-correlated wavelets of mixed high frequency and high temporal resolution respectively to attenuate frequency and motion alias. Applied to the human and piglet data, the method resolves individual arterial and venous PWs and finds them to be phase locked each with separate phase relations to brain pulse motion. This is consistent with arterial and venous PW coordination mediated by pulse motion and points to a testable hypothesis of a function of cerebrospinal fluid in the ventricles of the brain.

  15. Chaos control of third-order phase-locked loops using backstepping nonlinear controller

    International Nuclear Information System (INIS)

    Harb, Ahmad M.; Harb, Bassam A.

    2004-01-01

    Previous study showed that a third-order phase-locked loop (PLL) with sinusoidal phase detector characteristics experienced a Hopf bifurcation point as well as chaotic behavior. As a result, this behavior drives the PLL to the out-of-lock (unstable) state. The analysis was based on a modern nonlinear theory such as bifurcation and chaos. The main goal of this paper is to control this chaotic behavior. A nonlinear controller based on the theory of backstepping is designed. The study showed the effectiveness of the designed nonlinear controller in controlling the undesirable unstable behavior and pulling the PLL back to the in-lock state

  16. Phase locking in backward-wave oscillators with strong end reflections

    International Nuclear Information System (INIS)

    Nusinovich, G. S.; Sinitsyn, O. V.; Rodgers, J.; Shkvarunets, A. G.; Carmel, Y.

    2007-01-01

    The theory of phase-locked oscillations in a backward-wave oscillator with strong end reflections is developed. Numerical results demonstrate that the locking bandwidth of such a device phase-locked by a prebunched electron beam can be twice the bandwidth of a resonator formed by a waveguide with strong end reflections. It is also shown that the device can operate with the efficiency exceeding 50% and that, in some cases, it can exhibit a hysteresis in the process of tuning the signal frequency. The applicability of the results obtained to the experiments with the plasma-assisted backward-wave oscillator currently underway at the University of Maryland is discussed

  17. Single-Phase Phase-Locked Loop Based on Derivative Elements

    DEFF Research Database (Denmark)

    Guan, Qingxin; Zhang, Yu; Kang, Yong

    2017-01-01

    High-performance phase-locked loops (PLLs) are critical for power control in grid-connected systems. This paper presents a new method of designing a PLL for single-phase systems based on derivative elements (DEs). The quadrature signal generator (QSG) is constructed by two DEs with the same...... PLL to achieve high performance when the grid frequency changes rapidly. This paper presents the model of the PLL and a theoretical performance analysis with respect to both the frequency-domain and time-domain behavior. The error arising from the discretization process is also compensated, ensuring...

  18. A GPS Phase-Locked Loop Performance Metric Based on the Phase Discriminator Output.

    Science.gov (United States)

    Stevanovic, Stefan; Pervan, Boris

    2018-01-19

    We propose a novel GPS phase-lock loop (PLL) performance metric based on the standard deviation of tracking error (defined as the discriminator's estimate of the true phase error), and explain its advantages over the popular phase jitter metric using theory, numerical simulation, and experimental results. We derive an augmented GPS phase-lock loop (PLL) linear model, which includes the effect of coherent averaging, to be used in conjunction with this proposed metric. The augmented linear model allows more accurate calculation of tracking error standard deviation in the presence of additive white Gaussian noise (AWGN) as compared to traditional linear models. The standard deviation of tracking error, with a threshold corresponding to half of the arctangent discriminator pull-in region, is shown to be a more reliable/robust measure of PLL performance under interference conditions than the phase jitter metric. In addition, the augmented linear model is shown to be valid up until this threshold, which facilitates efficient performance prediction, so that time-consuming direct simulations and costly experimental testing can be reserved for PLL designs that are much more likely to be successful. The effect of varying receiver reference oscillator quality on the tracking error metric is also considered.

  19. Phase-locking of bursting neuronal firing to dominant LFP frequency components.

    Science.gov (United States)

    Constantinou, Maria; Elijah, Daniel H; Squirrell, Daniel; Gigg, John; Montemurro, Marcelo A

    2015-10-01

    Neuronal firing in the hippocampal formation relative to the phase of local field potentials (LFP) has a key role in memory processing and spatial navigation. Firing can be in either tonic or burst mode. Although bursting neurons are common in the hippocampal formation, the characteristics of their locking to LFP phase are not completely understood. We investigated phase-locking properties of bursting neurons using simulations generated by a dual compartmental model of a pyramidal neuron adapted to match the bursting activity in the subiculum of a rat. The model was driven with stochastic input signals containing a power spectral profile consistent with physiologically relevant frequencies observed in LFP. The single spikes and spike bursts fired by the model were locked to a preferred phase of the predominant frequency band where there was a peak in the power of the driving signal. Moreover, the preferred phase of locking shifted with increasing burst size, providing evidence that LFP phase can be encoded by burst size. We also provide initial support for the model results by analysing example data of spontaneous LFP and spiking activity recorded from the subiculum of a single urethane-anaesthetised rat. Subicular neurons fired single spikes, two-spike bursts and larger bursts that locked to a preferred phase of either dominant slow oscillations or theta rhythms within the LFP, according to the model prediction. Both power-modulated phase-locking and gradual shift in the preferred phase of locking as a function of burst size suggest that neurons can use bursts to encode timing information contained in LFP phase into a spike-count code. Copyright © 2015 The Authors. Published by Elsevier Ireland Ltd.. All rights reserved.

  20. A Fast EEG Forecasting Algorithm for Phase-Locked Transcranial Electrical Stimulation of the Human Brain

    Directory of Open Access Journals (Sweden)

    Farrokh Mansouri

    2017-07-01

    Full Text Available A growing body of research suggests that non-invasive electrical brain stimulation can more effectively modulate neural activity when phase-locked to the underlying brain rhythms. Transcranial alternating current stimulation (tACS can potentially stimulate the brain in-phase to its natural oscillations as recorded by electroencephalography (EEG, but matching these oscillations is a challenging problem due to the complex and time-varying nature of the EEG signals. Here we address this challenge by developing and testing a novel approach intended to deliver tACS phase-locked to the activity of the underlying brain region in real-time. This novel approach extracts phase and frequency from a segment of EEG, then forecasts the signal to control the stimulation. A careful tuning of the EEG segment length and prediction horizon is required and has been investigated here for different EEG frequency bands. The algorithm was tested on EEG data from 5 healthy volunteers. Algorithm performance was quantified in terms of phase-locking values across a variety of EEG frequency bands. Phase-locking performance was found to be consistent across individuals and recording locations. With current parameters, the algorithm performs best when tracking oscillations in the alpha band (8–13 Hz, with a phase-locking value of 0.77 ± 0.08. Performance was maximized when the frequency band of interest had a dominant frequency that was stable over time. The algorithm performs faster, and provides better phase-locked stimulation, compared to other recently published algorithms devised for this purpose. The algorithm is suitable for use in future studies of phase-locked tACS in preclinical and clinical applications.

  1. Timely event-related synchronization fading and phase de-locking and their defects in migraine.

    Science.gov (United States)

    Yum, Myung-Kul; Moon, Jin-Hwa; Kang, Joong Koo; Kwon, Oh-Young; Park, Ki-Jong; Shon, Young-Min; Lee, Il Keun; Jung, Ki-Young

    2014-07-01

    To investigate the characteristics of event-related synchronization (ERS) fading and phase de-locking of alpha waves during passive auditory stimulation (PAS) in the migraine patients. The subjects were 16 adult women with migraine and 16 normal controls. Electroencephalographic (EEG) data obtained during PAS with standard (SS) and deviant stimuli (DS) were used. Alpha ERS fading, the phase locking index (PLI) and de-locking index (DLI) were evaluated from the 10 Hz complex Morlet wavelet components at 100 ms (t100) and 300 ms (t300) after PAS. At t100, significant ERS was found with SS and DS in the migraineurs and controls (P=0.000). At t300 in the controls, ERS faded to zero for DS while in the migraineurs there was no fading for DS. In both groups the PLI for SS and DS was significantly reduced, i.e. de-locked, at t300 compared to t100 (P=0.000). In the migraineurs, the DLI for DS was significantly lower than in the controls (P=0.003). The alpha ERS fading and phase de-locking are defective in migraineurs during passive auditory cognitive processing. The defects in timely alpha ERS fading and in de-locking may play a role in the different attention processing in migraine patients. Copyright © 2013 International Federation of Clinical Neurophysiology. Published by Elsevier Ireland Ltd. All rights reserved.

  2. Efficient Phase Locking of Fiber Amplifiers Using a Low-Cost and High-Damage-Threshold Phase Control System

    International Nuclear Information System (INIS)

    Pu, Zhou; Yan-Xing, Ma; Xiao-Lin, Wang; Hao-Tong, Ma; Xiao-Jun, Xu; Ze-Jin, Liu

    2010-01-01

    We propose a low-cost and high-damage-threshold phase control system that employs a piezoelectric ceramic transducer modulator controlled by a stochastic parallel gradient descent algorithm. Efficient phase locking of two fiber amplifiers is demonstrated. Experimental results show that energy encircled in the target pinhole is increased by a factor of 1.76 and the visibility of the fringe pattern is as high as 90% when the system is in close-loop. The phase control system has potential in phase locking of large-number and high-power fiber laser endeavors. (fundamental areas of phenomenology (including applications))

  3. Injection Bucket Jitter Compensation Using Phase Lock System at Fermilab Booster

    Energy Technology Data Exchange (ETDEWEB)

    Seiya, K. [Fermilab; Drennan, C. [Fermilab; Pellico, W. [Fermilab; Chaurize, S. [Fermilab

    2017-05-12

    The extraction bucket position in the Fermilab Booster is controlled with a cogging process that involves the comparison of the Booster rf count and the Recycler Ring revolution marker. A one rf bucket jitter in the ex-traction bucket position results from the variability of the process that phase matches the Booster to the Recycler. However, the new slow phase lock process used to lock the frequency and phase of the Booster rf to the Recycler rf has been made digital and programmable and has been modified to correct the extraction notch position. The beam loss at the Recycler injection has been reduced by 20%. Beam studies and the phase lock system will be discussed in this paper.

  4. Quadrature entanglement and photon-number correlations accompanied by phase-locking

    International Nuclear Information System (INIS)

    Adamyan, H. H.; Manvelyan, S. B.; Adamyan, N. H.; Kryuchkyan, G. Yu.

    2006-01-01

    We investigate quantum properties of phase-locked light beams generated in a nondegenerate optical parametric oscillator (NOPO) with an intracavity waveplate. This investigation continues our previous analysis presented in Phys. Rev. A 69, 053814 (2004), and involves problems of continuous-variable quadrature entanglement in the spectral domain, photon-number correlations as well as the signatures of phase-locking in the Wigner function. We study the role of phase-localizing processes on the quantum correlation effects. The peculiarities of phase-locked NOPO in the self-pulsing instability operational regime are also cleared up. The results are obtained in the P-representation as a quantum-mechanical calculation in the framework of stochastic equations of motion, as well as by numerical simulation based on the method of quantum state diffusion

  5. Mode-locking of a terahertz laser by direct phase synchronization.

    Science.gov (United States)

    Maysonnave, J; Maussang, K; Freeman, J R; Jukam, N; Madéo, J; Cavalié, P; Rungsawang, R; Khanna, S P; Linfield, E H; Davies, A G; Beere, H E; Ritchie, D A; Dhillon, S S; Tignon, J

    2012-09-10

    A novel scheme to achieve mode-locking of a multimode laser is demonstrated. Traditional methods to produce ultrashort laser pulses are based on modulating the cavity gain or losses at the cavity roundtrip frequency, favoring the pulsed emission. Here, we rather directly act on the phases of the modes, resulting in constructive interference for the appropriated phase relationship. This was performed on a terahertz quantum cascade laser by multimode injection seeding with an external terahertz pulse, resulting in phase mode-locked terahertz laser pulses of 9 ps duration, characterized unambiguously in the time domain.

  6. Phase-locked high-order-harmonic and sub-100-as pulse generation from stretched molecules

    International Nuclear Information System (INIS)

    Lan Pengfei; Lu Peixiang; Cao Wei; Wang Xinlin; Yang Guang

    2006-01-01

    High harmonic generation from diatomic molecules in a linearly polarized intense laser field is investigated and the emission time of the harmonics is discussed with the time-frequency analysis method. It is shown that high harmonic generation from molecules at equilibrium distance is similar to that from atoms. Only the harmonics in the cutoff are synchronized, i.e., well phase-locked, whereas the other harmonics are not phase-locked. For the molecule stretched well beyond its equilibrium distance, the harmonics exhibit distinct time-frequency characteristics. The harmonic spectrum can be extended to I p +8U p , where I p and U p are the ionization and ponderomotive potential, and the harmonics with energies below I p +3.17U p are not phase-locked and the harmonics with energies beyond I p +3.17U p are well phase-locked. Thus a large range of harmonics which are well phase-locked are produced, and a train of clean attosecond (as) pulses with a single 90-as pulse in each half optical cycle can be generated with a multicycle laser pulse. Using a few-cycle laser pulse, an isolated attosecond pulse with a duration of about 95 as is obtained

  7. QPSK Modulator with Continuous Phase and Fast Response Based on Phase-Locked Loop

    Directory of Open Access Journals (Sweden)

    L. Kirasamuthranon

    2017-06-01

    Full Text Available Among M-phase shift keying (M-PSK schemes, quadrature phase-shift keying (QPSK is used most often because of its efficient bandwidth consumption. However, in comparison with minimum-shift keying, which has continuous phase transitions, QPSK requires a higher bandwidth to transmit a signal. This article focuses on the phase transitions in QPSK signals, and a QPSK modulator based on a phase-locked loop (PLL is proposed. The PLL circuit in the proposed system differs from that of conventional PLL circuits because a three-input XOR gate and a summing circuit are used. With these additional components, the proposed PLL provides a continuous phase change in the QPSK signal. Consequently, the required bandwidth for transmitting the QPSK signal when using the proposed circuit is less than that for a conventional QPSK signal with a discontinuous phase. The analytical results for the proposed system in the time domain agree well with the experimental and simulation results of the circuit. Both the theoretical and experimental results thus confirm that the proposed technique can be realized in real-world applications.

  8. A Phase-Locked Loop Continuous Wave Sonic Anemometer-Thermometer

    DEFF Research Database (Denmark)

    Larsen, Søren Ejling; Weller, F. W.; Busings, J. A.

    1979-01-01

    A continuous wake sonic anemometer-thermometer has been developed for simultaneous measurements of vertical velocity and temperature. The phase angle fluctuations are detected by means of a monolithic integrated phase-locked loop, the latter feature providing for inexpensive and accurate...

  9. Phase-locking of a terahertz solid-state source using a superconducting hot-electron bolometer mixer

    International Nuclear Information System (INIS)

    Miao, W; Zhang, W; Zhou, K M; Li, S L; Zhang, K; Duan, W Y; Yao, Q J; Shi, S C

    2013-01-01

    We report on a scheme whereby the local-oscillator (LO) of a THz heterodyne receiver can be phase-locked by the mixer of the heterodyne receiver. This scheme is demonstrated for the phase-locking of an 847.6 GHz Gunn oscillator and multiplier chain combined source with a superconducting hot-electron bolometer (HEB) mixer. We show that with this technique the phase-locked beat signal can reach a signal-to-noise ratio higher than 70 dB in a resolution bandwidth (RBW) of 1 Hz. This phase-locking scheme should find good use in THz heterodyne spectrometers. (paper)

  10. Phase noise analysis of clock recovery based on an optoelectronic phase-locked loop

    DEFF Research Database (Denmark)

    Zibar, Darko; Mørk, Jesper; Oxenløwe, Leif Katsuo

    2007-01-01

    A detailed theoretical analysis of a clock-recovery (CR) scheme based on an optoelectronic phase-locked loop is presented. The analysis emphasizes the phase noise performance, taking into account the noise of the input data signal, the local voltage-controlled oscillator (VCO), and the laser....... It is shown that a large loop length results in a higher timing jitter of the recovered clock signal. The impact of the loop length on the clock signal jitter can be reduced by using a low-noise VCO and a low loop filter bandwidth. Using the model, the timing jitter of the recovered optical and electrical...... clock signal can be evaluated. We numerically investigate the timing jitter requirements for combined electrical/optical local oscillators, in order for the recovered clock signal to have less jitter than that of the input signal. The timing jitter requirements for the free-running laser and the VCO...

  11. Common mode frequency instability in internally phase-locked terahertz quantum cascade lasers.

    Science.gov (United States)

    Wanke, M C; Grine, A D; Fuller, C T; Nordquist, C D; Cich, M J; Reno, J L; Lee, Mark

    2011-11-21

    Feedback from a diode mixer integrated into a 2.8 THz quantum cascade laser (QCL) was used to phase lock the difference frequencies (DFs) among the Fabry-Perot (F-P) longitudinal modes of a QCL. Approximately 40% of the DF power was phase locked, consistent with feedback loop bandwidth of 10 kHz and phase noise bandwidth ~0.5 MHz. While the locked DF signal has ≤ 1 Hz linewidth and negligible drift over ~30 min, mixing measurements between two QCLs and between a QCL and molecular gas laser show that the common mode frequency stability is no better than a free-running QCL. © 2011 Optical Society of America

  12. Phase Locking of a 2.7 THz Quantum Cascade Laser to a Microwave Reference

    Science.gov (United States)

    Khosropanah, P.; Baryshev, A.; Zhang, W.; Jellema, W.; Hovenier, J. N.; Gao, J. R.; Klapwijk, T. M.; Paveliev, D. G.; Williams, B. S.; Hu, Q.; hide

    2009-01-01

    We demonstrate the phase locking of a 2.7 THz metal-metal waveguide quantum cascade laser (QCL) to an external microwave signal. The reference is the 15th harmonic, generated by a semiconductor superlattice nonlinear device, of a signal at 182 GHz, which itself is generated by a multiplier chain (x 12) from a microwave synthesizer at approx. 15 GHz. Both laser and reference radiations are coupled into a bolometer mixer, resulting in a beat signal, which is fed into a phase-lock loop. The spectral analysis of the beat signal confirms that the QCL is phase locked. This result opens the possibility to extend heterodyne interferometers into the far-infrared range.

  13. Coherent Optical Generation of a 6 GHz Microwave Signal with Directly Phase Locked Semiconductor DFB Lasers

    DEFF Research Database (Denmark)

    Gliese, Ulrik Bo; Nielsen, Torben Nørskov; Bruun, Marlene

    1992-01-01

    Experimental results of a wideband heterodyne second order optical phase locked loop with 1.5 ¿m semiconductor lasers are presented. The loop has a bandwidth of 180 MHz, a gain of 181 dBHz and a propagation delay of only 400 ps. A beat signal of 8 MHz linewidth is phase locked to become a replica...... of a microwave reference source close to carrier with a noise level of ¿125 dBc/Hz. The total phase variance of the locked carrier is 0.04 rad2 and carriers can be generated in a continuous range from 3 to 18 GHz. The loop reliability is excellent with an average time to cycle slip of 1011 seconds...

  14. Phase noise mitigation of QPSK signal utilizing phase-locked multiplexing of signal harmonics and amplitude saturation.

    Science.gov (United States)

    Mohajerin-Ariaei, Amirhossein; Ziyadi, Morteza; Chitgarha, Mohammad Reza; Almaiman, Ahmed; Cao, Yinwen; Shamee, Bishara; Yang, Jeng-Yuan; Akasaka, Youichi; Sekiya, Motoyoshi; Takasaka, Shigehiro; Sugizaki, Ryuichi; Touch, Joseph D; Tur, Moshe; Langrock, Carsten; Fejer, Martin M; Willner, Alan E

    2015-07-15

    We demonstrate an all-optical phase noise mitigation scheme based on the generation, delay, and coherent summation of higher order signal harmonics. The signal, its third-order harmonic, and their corresponding delayed variant conjugates create a staircase phase-transfer function that quantizes the phase of quadrature-phase-shift-keying (QPSK) signal to mitigate phase noise. The signal and the harmonics are automatically phase-locked multiplexed, avoiding the need for phase-based feedback loop and injection locking to maintain coherency. The residual phase noise converts to amplitude noise in the quantizer stage, which is suppressed by parametric amplification in the saturation regime. Phase noise reduction of ∼40% and OSNR-gain of ∼3  dB at BER 10(-3) are experimentally demonstrated for 20- and 30-Gbaud QPSK input signals.

  15. Phase Locking of Laser Diode Array by Using an Off-Axis External Talbot Cavity

    International Nuclear Information System (INIS)

    Su Zhou-Ping; Zhu Zhuo-Wei; Que Li-Zhi; Zhu Yun; Ji Zhi-Cheng

    2012-01-01

    Phase locking of a laser diode array is demonstrated experimentally by using an off-axis external Talbot cavity with a feedback plane mirror. Due to good spatial mode discrimination, the cavity does not need a spatial filter. By employing the cavity, a clear and stable far-field interference pattern can be observed when the driver current is less than 14 A. In addition, the spectral line width can be reduced to 0.8 nm. The slope efficiency of the phase-locked laser diode array is about 0.62 W/A. (fundamental areas of phenomenology(including applications))

  16. Excitation power quantities in phase resonance testing of nonlinear systems with phase-locked-loop excitation

    Science.gov (United States)

    Peter, Simon; Leine, Remco I.

    2017-11-01

    Phase resonance testing is one method for the experimental extraction of nonlinear normal modes. This paper proposes a novel method for nonlinear phase resonance testing. Firstly, the issue of appropriate excitation is approached on the basis of excitation power considerations. Therefore, power quantities known from nonlinear systems theory in electrical engineering are transferred to nonlinear structural dynamics applications. A new power-based nonlinear mode indicator function is derived, which is generally applicable, reliable and easy to implement in experiments. Secondly, the tuning of the excitation phase is automated by the use of a Phase-Locked-Loop controller. This method provides a very user-friendly and fast way for obtaining the backbone curve. Furthermore, the method allows to exploit specific advantages of phase control such as the robustness for lightly damped systems and the stabilization of unstable branches of the frequency response. The reduced tuning time for the excitation makes the commonly used free-decay measurements for the extraction of backbone curves unnecessary. Instead, steady-state measurements for every point of the curve are obtained. In conjunction with the new mode indicator function, the correlation of every measured point with the associated nonlinear normal mode of the underlying conservative system can be evaluated. Moreover, it is shown that the analysis of the excitation power helps to locate sources of inaccuracies in the force appropriation process. The method is illustrated by a numerical example and its functionality in experiments is demonstrated on a benchmark beam structure.

  17. Locking the local oscillator phase to the atomic phase via weak measurement

    International Nuclear Information System (INIS)

    Shiga, N; Takeuchi, M

    2012-01-01

    A new method is proposed to reduce the frequency noise of a local oscillator to the level of white phase noise by maintaining (not destroying by projective measurement) the coherence of the ensemble pseudo-spin of atoms over many measurement cycles. This method, which we call ‘atomic phase lock (APL)’, uses weak measurement to monitor the phase in the Ramsey method and repeat the cycle without initialization of the phase. APL will achieve white phase noise as long as the noise accumulated during dead time and the decoherence are smaller than the measurement noise. A numerical simulation confirmed that with APL, the Allan deviation is averaged down at a maximum rate that is proportional to the inverse of the total measurement time, τ -1 . In contrast, current atomic clocks that use projection measurement suppress the noise only to the white frequency noise level, in which case the Allan deviation scales as τ -1/2 . Faraday rotation is one way to achieve weak measurement for APL. The strength of Faraday rotation with 171 Yb + ions trapped in a linear rf-trap is evaluated, and the performance of APL is discussed. The main source of decoherence is a spontaneous emission, induced by the probe beam for Faraday rotation measurement. The Faraday rotation measurement can be repeated until the decoherence becomes comparable to the signal-to-noise ratio of the measurement. The number of cycles for a realistic experimental parameter is estimated to be ∼100. (paper)

  18. Toroidally asymmetric particle transport caused by phase-locking of MHD modes in RFX-mod

    International Nuclear Information System (INIS)

    Lorenzini, R.; Terranova, D.; Auriemma, F.; Cavazzana, R.; Innocente, P.; Martini, S.; Serianni, G.; Zuin, M.

    2007-01-01

    The particle and energy transport in reversed field pinch experiments is affected by the locking in phase of the tearing modes, also dubbed dynamo modes, that sustain the magnetic configuration. In standard RFP pulses many m = 1 and m = 0 resonant modes have a relatively large amplitude (a spectrum dubbed MH for multiple helicity). The locking in phase of m = 1 tearing modes produces a helical deformation (locked mode (LM)) of the magnetic surfaces in a region of approximately 40 toroidal degrees. The region of the LM is characterized by a strong plasma-wall interaction and by high losses of energy and particles that account for a significant fraction of the input power and of the total particle outflux. The locking in phase of m = 0 modes modifies the plasma radius, shrinking and enlarging the plasma cross section in two wide toroidal regions of about 100 0 . The purpose of this paper is to investigate to what extent the locking in phase of m = 0 modes introduces toroidal asymmetries in the transport properties of the plasma. This study has been carried out investigating the shape of the density profile in the RFX-mod experiment. The analyses show that the profile exhibits a dependence on the toroidal angle, which is related to the deformation of the plasma column due to the locking in phase of m = 0 modes: the least steep density gradients at the edge are found in the region where the plasma column is shrunk, entailing that in this region the particle transport is enhanced. An analogous asymmetry also characterizes the density and magnetic fluctuations at the edge, which are enhanced in the same toroidal region where the particle transport also is enhanced. This result can be considered the first experimental evidence of an instability localized where the plasma column is shrunk

  19. Global stability of phase lock near a chaotic crisis in the rf-biased Josephson junction

    International Nuclear Information System (INIS)

    Kautz, R.L.

    1987-01-01

    The global stability of phase lock in the rf-biased Josephson junction is studied through digital simulations. Global stability is determined by calculating the lifetime of the phase-locked state in the presence of thermal noise. This lifetime, the mean time required for thermal noise to induce a 2π phase slip, increases exponentially with inverse temperature in the limit of low temperatures, and the low-temperature asymptote can be parametrized in terms of an activation energy E-script and an attempt time tau 0 . The activation energy is a useful measure of global stability for both periodic and chaotic phase-locked states. The behavior of E-script and tau 0 is studied over a range of critical-current densities which take the system from a region of harmonic motion through a period-doubling cascade and into a region of phase-locked chaotic behavior which is ended by a chaotic crisis. At the crisis point, the activation energy goes to zero and the attempt time goes to infinity. The results are used to determine the optimum critical-current density for series-array voltage standards

  20. Development of Phase Lock Loop System for Synchronisation of a Hybrid System with the Grid

    Directory of Open Access Journals (Sweden)

    A. S. Abubakar

    2016-06-01

    Full Text Available Phase locked loop (PLL is an important part of the control unit of the grid connected power converter. The method of zero crossing detection (ZCD does not produce accurate phase information when grid is non-ideal. In this work, a synchronous reference frame (SRF PLL method to obtain accurate phase information when the grid voltages are unbalanced is proposed. The performances of the PLL have been verified for ideal and abnormal grid conditions such as unbalance, voltage sag, faults condition etc. Based on the results obtained, the developed PLL gives better fault ride when unbalances in the three phase input signals are overall handled well by the PLL system as it locks the two signal back within the first cycle. It also overcomes a phase jump after 5 milli-seconds from the time the fault was introduced and performs better tracking of the grid voltage and that of the renewable energy source.

  1. Development of Phase Lock Loop System for Synchronisation of a Hybrid System with the Grid

    Directory of Open Access Journals (Sweden)

    A. S. Abubakar

    2016-12-01

    Full Text Available Phase locked loop (PLL is an important part of the control unit of the grid connected power converter. The method of zero crossing detection (ZCD does not produce accurate phase information when grid is non-ideal. In this work, a synchronous reference frame (SRF PLL method to obtain accurate phase information when the grid voltages are unbalanced is proposed. The performances of the PLL have been verified for ideal and abnormal grid conditions such as unbalance, voltage sag, faults condition etc. Based on the results obtained, the developed PLL gives better fault ride when unbalances in the three phase input signals are overall handled well by the PLL system as it locks the two signal back within the first cycle. It also overcomes a phase jump after 5 milli-seconds from the time the fault was introduced and performs better tracking of the grid voltage and that of the renewable energy source.

  2. Phase Locking of Multiple Single Neurons to the Local Field Potential in Cat V1.

    Science.gov (United States)

    Martin, Kevan A C; Schröder, Sylvia

    2016-02-24

    The local field potential (LFP) is thought to reflect a temporal reference for neuronal spiking, which may facilitate information coding and orchestrate the communication between neural populations. To explore this proposed role, we recorded the LFP and simultaneously the spike activity of one to three nearby neurons in V1 of anesthetized cats during the presentation of drifting sinusoidal gratings, binary dense noise stimuli, and natural movies. In all stimulus conditions and during spontaneous activity, the average LFP power at frequencies >20 Hz was higher when neurons were spiking versus not spiking. The spikes were weakly but significantly phase locked to all frequencies of the LFP. The average spike phase of the LFP was stable across high and low levels of LFP power, but the strength of phase locking at low frequencies (≤10 Hz) increased with increasing LFP power. In a next step, we studied how strong stimulus responses of single neurons are reflected in the LFP and the LFP-spike relationship. We found that LFP power was slightly increased and phase locking was slightly stronger during strong compared with weak stimulus-locked responses. In summary, the coupling strength between high frequencies of the LFP and spikes was not strongly modulated by LFP power, which is thought to reflect spiking synchrony, nor was it strongly influenced by how strongly the neuron was driven by the stimulus. Furthermore, a comparison between neighboring neurons showed no clustering of preferred LFP phase. We argue that hypotheses on the relevance of phase locking in their current form are inconsistent with our findings. Copyright © 2016 the authors 0270-6474/16/362494-09$15.00/0.

  3. Phase locking of a 2.7 THz quantum cascade laser to a microwave reference

    NARCIS (Netherlands)

    Khosropanah, P.; Baryshev, A.; Zhang, W.; Jellema, W.; Hovenier, J.N.; Gao, J.R.; Klapwijk, T.M.; Paveliev, D.G.; Williams, B.S.; Kumar, S.; Hu, Q.; Reno, J.L.; Klein, B.; Hesler, J.L.

    2009-01-01

    We demonstrate the phase locking of a 2.7 THz metal–metal waveguide quantum cascade laser (QCL) to an external microwave signal. The reference is the 15th harmonic, generated by a semiconductor superlattice nonlinear device, of a signal at 182 GHz, which itself is generated by a multiplier chain

  4. Phase locking of a 2.7 THz quantum cascade laser to a microwave reference

    NARCIS (Netherlands)

    Khosropanah, P.; Baryshev, A.; Zhang, W.; Jellema, W.; Hovenier, J. N.; Gao, J. R.; Klapwijk, T. M.; Paveliev, D. G.; Williams, B. S.; Kumar, S.; Hu, Q.; Reno, J. L.; Klein, B.; Hesler, J. L.

    2009-01-01

    We demonstrate the phase locking of a 2.7 THz metal-metal waveguide quantum cascade laser (QCL) to an external microwave signal. The reference is the 15th harmonic, generated by a semiconductor superlattice nonlinear device, of a signal at 182 GHz, which itself is generated by a multiplier chain

  5. Mutual Phase Locking of Fluxons in Stacked Long Josephson Junctions: Simulations and Experiment

    DEFF Research Database (Denmark)

    Carapella, Giovanni; Costabile, Giovanni; Filatrella, Giovanni

    1997-01-01

    We report on the experimental observation of reciprocal phase-locking in stacked $Nb-AlO_x-Nb$ Josephson junctions having overlap geometry. When the junctions are independently biased in zero external magnetic field, they each exhibit several Zero Field Steps. Biasing both the junctions on the Ze...

  6. Phase-locking phenomena and excitation of damped and driven nonlinear oscillators

    DEFF Research Database (Denmark)

    Shagalov, A.G.; Juul Rasmussen, Jens; Naulin, Volker

    2009-01-01

    Resonant phase-locking phenomena ('autoresonance') in the van der Pol Duffing oscillator forced by a small amplitude periodic driving with slowly varying frequency have been studied. We show that autoresonance occurs for oscillators with sufficiently small damping, when the system may have bi-stable...

  7. Wide-band residual phase-noise measurements on 40-GHz monolithic mode-locked lasers

    DEFF Research Database (Denmark)

    Larsson, David; Hvam, Jørn Märcher

    2005-01-01

    We have performed wide-band residual phase-noise measurements on semiconductor 40-GHz mode-locked lasers by employing electrical waveguide components for the radio-frequency circuit. The intrinsic timing jitters of lasers with one, two, and three quantum wells (QW) are compared and our design......-QW laser. There is good agreement between the measured results and existing theory....

  8. Phase-locking regions in a forced model of slow insulin and glucose oscillations

    DEFF Research Database (Denmark)

    Sturis, Jeppe; Knudsen, Carsten; O'Meara, Niall M.

    1995-01-01

    We present a detailed numerical investigation of the phase-locking regions in a forced model of slow oscillations in human insulin secretion and blood glucose concentration. The bifurcation structures of period 2pi and 4pi tongues are mapped out and found to be qualitatively identical to those...

  9. Phase-locking regions in a forced model of slow insulin and glucose oscillations

    DEFF Research Database (Denmark)

    Sturis, J.; Knudsen, C.; O'Meara, N.M.

    1996-01-01

    We present a detailed numerical investigation of the phase-locking regions in a forced model of slow oscillations in human insulin secretion and blood glucose concentration. The bifurcation structures of period 2pi and 4pi tongues are mapped out and found to be qualitatively identical to those...

  10. Conventional Synchronous Reference Frame Phase-Locked Loop Is An Adaptive Complex Filter

    DEFF Research Database (Denmark)

    Golestan, Saeed; Guerrero, Josep M.

    2015-01-01

    Despite the wide acceptance and use of the conventional synchronous reference frame phase-locked loop (SRFPLL) no transfer function describing its actual input-output relationship has been developed so far. Arguably, the absence of such transfer function has hampered the application of SRF...

  11. Self-injection is a success

    DEFF Research Database (Denmark)

    Jensen, Jonna Gintberg; Høi, Henriette Brahe

    these people have so far received injections from their own doctor. Many of the 29 feel healthy, are on the labor market and live a normal life. Therefore, it may be a recurring nuisance having to consult their physician monthly to get the injection. On this background, it is believed that self......-injection will increase the individual's quality of life. For that reason this project on quality assurance of the 29 citizens current quality of life, if they want training for self-administration in our hospital unit, and follow-up contact about how self-injections are going on. Method for data generation: Data...... out qualitative interviews Transcription of interview material Follow-up telephone interviews Analysis (Steiner Kvale's three operational levels) Significant findings: Causes of training for self-administration is desired. Family doctor injects quickly – which gives bruising, and may bleed profusely...

  12. Inter-trial alignment of EEG data and phase-locking

    Science.gov (United States)

    Testorf, M. E.; Horak, P.; Connolly, A.; Holmes, G. L.; Jobst, B. C.

    2015-09-01

    Neuro-scientific studies are often aimed at imaging brain activity, which is time-locked to external stimuli. This provides the possibility to use statistical methods to extract even weak signal components, which occur with each stimulus. For electroencephalographic recordings this concept is limited by inevitable time jitter, which cannot be controlled in all cases. Our study is based on a cross-correlation analysis of trials to alignment trials based on the recorded data. This is demonstrated both with simulated signals and with clinical EEG data, which were recorded intracranially. Special attention is given to the evaluation of the time-frequency resolved phase-locking across multiple trails.

  13. A phase locked neutron chopper rotor drive system

    International Nuclear Information System (INIS)

    Wallace-Sims, G.R.

    1980-09-01

    A system is described for synchronising up to four neutron chopper rotors to an externally generated master pulse source. Phasing is adjustable in 1 0 steps from 0 to 360 0 relative to the master pulses. Additionally a pulse adjustable in phase is generated for initiating time of flight analyser equipment. (author)

  14. Development of high resolution Michelson interferometer for stable phase-locked ultrashort pulse pair generation.

    Science.gov (United States)

    Okada, Takumi; Komori, Kazuhiro; Goshima, Keishiro; Yamauchi, Shohgo; Morohashi, Isao; Sugaya, Takeyoshi; Ogura, Mutsuo; Tsurumachi, Noriaki

    2008-10-01

    We developed a high resolution Michelson interferometer with a two-frequency He-Ne laser positioning system in order to stabilize the relative phase of a pulse pair. The control resolution corresponded to a 12 as time resolution or a phase of 1.5 degrees at 900 nm. This high resolution Michelson interferometer can generate a phase-locked pulse pair either with a specific relative phase such as 0 or pi radians or with an arbitrary phase. Coherent control of an InAs self-assembled quantum dot was demonstrated using the high resolution Michelson interferometer with a microspectroscopy system.

  15. Multiple-Criteria Decision-Making in the Design of Innovative Lock Walls for Barge Impact; Phase 1

    National Research Council Canada - National Science Library

    Lambert, James

    2001-01-01

    .... This research project consists of two phases: Phase 1, which culminates with this report, investigated the use of multiple-criteria decision-making in the design process of lock approach walls to consider barge impact and earthquake loads...

  16. The rf sigmameter: A digital phase-locked technique for accurate long-range laser scanning

    International Nuclear Information System (INIS)

    Zhu, M.; Hall, J.L.

    1986-01-01

    The authors use a new version of a sigmameter, the two-channel field-widened rf sigmameter, to map optical frequency into the phase of an rf signal. This enables them to lock the laser frequency on the interferometer by using a phase-locked loop (PLL). Controlling the reference phase of the PLL electronically, they are able to scan the laser frequency over a long range step by step or with substeps. The systematic error of each substep is cancelled automatically when the authors change one step (which is ten substeps, for example), and that of each step is cancelled when they change the reference phase by 2π (which corresponds to 256 steps in their scheme)

  17. Spectrally resolved modal characteristics of leaky-wave-coupled quantum cascade phase-locked laser arrays

    Science.gov (United States)

    Sigler, Chris; Gibson, Ricky; Boyle, Colin; Kirch, Jeremy D.; Lindberg, Donald; Earles, Thomas; Botez, Dan; Mawst, Luke J.; Bedford, Robert

    2018-01-01

    The modal characteristics of nonresonant five-element phase-locked arrays of 4.7-μm emitting quantum cascade lasers (QCLs) have been studied using spectrally resolved near- and far-field measurements and correlated with results of device simulation. Devices are fabricated by a two-step metal-organic chemical vapor deposition process and operate predominantly in an in-phase array mode near threshold, although become multimode at higher drive levels. The wide spectral bandwidth of the QCL's core region is found to be a factor in promoting multispatial-mode operation at high drive levels above threshold. An optimized resonant-array design is identified to allow sole in-phase array-mode operation to high drive levels above threshold, and indicates that for phase-locked laser arrays full spatial coherence to high output powers does not require full temporal coherence.

  18. Phase-locking and bistability in neuronal networks with synaptic depression

    Science.gov (United States)

    Akcay, Zeynep; Huang, Xinxian; Nadim, Farzan; Bose, Amitabha

    2018-02-01

    We consider a recurrent network of two oscillatory neurons that are coupled with inhibitory synapses. We use the phase response curves of the neurons and the properties of short-term synaptic depression to define Poincaré maps for the activity of the network. The fixed points of these maps correspond to phase-locked modes of the network. Using these maps, we analyze the conditions that allow short-term synaptic depression to lead to the existence of bistable phase-locked, periodic solutions. We show that bistability arises when either the phase response curve of the neuron or the short-term depression profile changes steeply enough. The results apply to any Type I oscillator and we illustrate our findings using the Quadratic Integrate-and-Fire and Morris-Lecar neuron models.

  19. Generation of phase-locked and tunable continuous-wave radiation in the terahertz regime.

    Science.gov (United States)

    Quraishi, Qudsia; Griebel, Martin; Kleine-Ostmann, Thomas; Bratschitsch, Rudolf

    2005-12-01

    Broadly tunable phase-stable single-frequency terahertz radiation is generated with an optical heterodyne photomixer. The photomixer is excited by two near-infrared CW diode lasers that are phase locked to the stabilized optical frequency comb of a femtosecond titanium:sapphire laser. The terahertz radiation emitted by the photomixer is downconverted into RF frequencies with a waveguide harmonic mixer and measurement-limited linewidths at the Hertz level are demonstrated.

  20. Models for Master-Slave Clock Distribution Networks with Third-Order Phase-Locked Loops

    OpenAIRE

    Piqueira, José Roberto Castilho; de Carvalho Freschi, Marcela

    2007-01-01

    The purpose of this work is to study the processing and transmission of clock signals in networks of geographically distributed nodes, in order to derive conditions for frequency and phase synchronization between the nodes. The focus is on the master-slave architecture, which presents a priority scheme of clock distribution. One-way master-slave (OWMS ) and two-way master-slave (TWMS) chains are studied, considering that the slave nodes are third-order phase-locked loops...

  1. Phase locking of a seven-channel continuous wave fibre laser system by a stochastic parallel gradient algorithm

    Energy Technology Data Exchange (ETDEWEB)

    Volkov, M V; Garanin, S G; Dolgopolov, Yu V; Kopalkin, A V; Kulikov, S M; Sinyavin, D N; Starikov, F A; Sukharev, S A; Tyutin, S V; Khokhlov, S V; Chaparin, D A [Russian Federal Nuclear Center ' All-Russian Research Institute of Experimental Physics' , Sarov, Nizhnii Novgorod region (Russian Federation)

    2014-11-30

    A seven-channel fibre laser system operated by the master oscillator – multichannel power amplifier scheme is the phase locked using a stochastic parallel gradient algorithm. The phase modulators on lithium niobate crystals are controlled by a multichannel electronic unit with the microcontroller processing signals in real time. The dynamic phase locking of the laser system with the bandwidth of 14 kHz is demonstrated, the time of phasing is 3 – 4 ms. (fibre and integrated-optical structures)

  2. Chapter 5: Modeling and Control of Three-Phase AC/DC Converter Including Phase-Locked Loop

    DEFF Research Database (Denmark)

    Zhou, Dao; Song, Yipeng; Blaabjerg, Frede

    2018-01-01

    In this chapter, a mathematical model of the power circuit of a three-phase AC/DC converter is developed in the stationary and synchronous reference frames. Then, the operation principle of the phasor locked loop is addressed to exact the angle information of the power grid to realize the accurat...

  3. Stability of phase locking in a ring of unidirectionally coupled oscillators

    International Nuclear Information System (INIS)

    Rogge, J A; Aeyels, D

    2004-01-01

    We discuss the dynamic behaviour of a finite group of phase oscillators unidirectionally coupled in a ring. The dynamics are based on the Kuramoto model. In the case of identical oscillators, all phase locking solutions and their stability properties are obtained. For nonidentical oscillators it is proven that there exist phase locking solutions for sufficiently strong coupling. An algorithm to obtain all phase locking solutions is proposed. These solutions can be classified into classes, each with its own stability properties. The stability properties are obtained by means of a novel extension of Gershgorin's theorem. One class of stable solutions has the property that all phase differences between neighbouring cells are contained in (-π/2, π/2). Contrary to intuition, a second class of stable solutions is established with exactly one of the phase differences contained in (π/2, 3π/2). The stability results are extended from sinusoidal interconnections to a class of odd functions. To conclude, a connection with the field of active antenna arrays is made, generalizing some results earlier obtained in this field

  4. Quantifying Neural Oscillatory Synchronization: A Comparison between Spectral Coherence and Phase-Locking Value Approaches

    Science.gov (United States)

    Lowet, Eric; Roberts, Mark J.; Bonizzi, Pietro; Karel, Joël; De Weerd, Peter

    2016-01-01

    Synchronization or phase-locking between oscillating neuronal groups is considered to be important for coordination of information among cortical networks. Spectral coherence is a commonly used approach to quantify phase locking between neural signals. We systematically explored the validity of spectral coherence measures for quantifying synchronization among neural oscillators. To that aim, we simulated coupled oscillatory signals that exhibited synchronization dynamics using an abstract phase-oscillator model as well as interacting gamma-generating spiking neural networks. We found that, within a large parameter range, the spectral coherence measure deviated substantially from the expected phase-locking. Moreover, spectral coherence did not converge to the expected value with increasing signal-to-noise ratio. We found that spectral coherence particularly failed when oscillators were in the partially (intermittent) synchronized state, which we expect to be the most likely state for neural synchronization. The failure was due to the fast frequency and amplitude changes induced by synchronization forces. We then investigated whether spectral coherence reflected the information flow among networks measured by transfer entropy (TE) of spike trains. We found that spectral coherence failed to robustly reflect changes in synchrony-mediated information flow between neural networks in many instances. As an alternative approach we explored a phase-locking value (PLV) method based on the reconstruction of the instantaneous phase. As one approach for reconstructing instantaneous phase, we used the Hilbert Transform (HT) preceded by Singular Spectrum Decomposition (SSD) of the signal. PLV estimates have broad applicability as they do not rely on stationarity, and, unlike spectral coherence, they enable more accurate estimations of oscillatory synchronization across a wide range of different synchronization regimes, and better tracking of synchronization-mediated information

  5. Quantifying Neural Oscillatory Synchronization: A Comparison between Spectral Coherence and Phase-Locking Value Approaches.

    Directory of Open Access Journals (Sweden)

    Eric Lowet

    Full Text Available Synchronization or phase-locking between oscillating neuronal groups is considered to be important for coordination of information among cortical networks. Spectral coherence is a commonly used approach to quantify phase locking between neural signals. We systematically explored the validity of spectral coherence measures for quantifying synchronization among neural oscillators. To that aim, we simulated coupled oscillatory signals that exhibited synchronization dynamics using an abstract phase-oscillator model as well as interacting gamma-generating spiking neural networks. We found that, within a large parameter range, the spectral coherence measure deviated substantially from the expected phase-locking. Moreover, spectral coherence did not converge to the expected value with increasing signal-to-noise ratio. We found that spectral coherence particularly failed when oscillators were in the partially (intermittent synchronized state, which we expect to be the most likely state for neural synchronization. The failure was due to the fast frequency and amplitude changes induced by synchronization forces. We then investigated whether spectral coherence reflected the information flow among networks measured by transfer entropy (TE of spike trains. We found that spectral coherence failed to robustly reflect changes in synchrony-mediated information flow between neural networks in many instances. As an alternative approach we explored a phase-locking value (PLV method based on the reconstruction of the instantaneous phase. As one approach for reconstructing instantaneous phase, we used the Hilbert Transform (HT preceded by Singular Spectrum Decomposition (SSD of the signal. PLV estimates have broad applicability as they do not rely on stationarity, and, unlike spectral coherence, they enable more accurate estimations of oscillatory synchronization across a wide range of different synchronization regimes, and better tracking of synchronization

  6. Analysis of first and second order binary quantized digital phase-locked loops for ideal and white Gaussian noise inputs

    Science.gov (United States)

    Blasche, P. R.

    1980-01-01

    Specific configurations of first and second order all digital phase locked loops are analyzed for both ideal and additive white gaussian noise inputs. In addition, a design for a hardware digital phase locked loop capable of either first or second order operation is presented along with appropriate experimental data obtained from testing of the hardware loop. All parameters chosen for the analysis and the design of the digital phase locked loop are consistent with an application to an Omega navigation receiver although neither the analysis nor the design are limited to this application.

  7. Phase-locking to a free-space terahertz comb for metrological-grade terahertz lasers.

    Science.gov (United States)

    Consolino, L; Taschin, A; Bartolini, P; Bartalini, S; Cancio, P; Tredicucci, A; Beere, H E; Ritchie, D A; Torre, R; Vitiello, M S; De Natale, P

    2012-01-01

    Optical frequency comb synthesizers have represented a revolutionary approach to frequency metrology, providing a grid of frequency references for any laser emitting within their spectral coverage. Extending the metrological features of optical frequency comb synthesizers to the terahertz domain would be a major breakthrough, due to the widespread range of accessible strategic applications and the availability of stable, high-power and widely tunable sources such as quantum cascade lasers. Here we demonstrate phase-locking of a 2.5 THz quantum cascade laser to a free-space comb, generated in a LiNbO(3) waveguide and covering the 0.1-6 THz frequency range. We show that even a small fraction (quantum cascade laser is sufficient to generate a beat note suitable for phase-locking to the comb, paving the way to novel metrological-grade terahertz applications, including high-resolution spectroscopy, manipulation of cold molecules, astronomy and telecommunications.

  8. Dual-Phase Lock-In Amplifier Based on FPGA for Low-Frequencies Experiments

    Directory of Open Access Journals (Sweden)

    Gonzalo Macias-Bobadilla

    2016-03-01

    Full Text Available Photothermal techniques allow the detection of characteristics of material without invading it. Researchers have developed hardware for some specific Phase and Amplitude detection (Lock-In Function applications, eliminating space and unnecessary electronic functions, among others. This work shows the development of a Digital Lock-In Amplifier based on a Field Programmable Gate Array (FPGA for low-frequency applications. This system allows selecting and generating the appropriated frequency depending on the kind of experiment or material studied. The results show good frequency stability in the order of 1.0 × 10−9 Hz, which is considered good linearity and repeatability response for the most common Laboratory Amplitude and Phase Shift detection devices, with a low error and standard deviation.

  9. Phase Locking and Chaos in a Josephson Junction Array Shunted by a Common Resistance

    International Nuclear Information System (INIS)

    Tie-Ge, Zhou; Jing, Mao; Ting-Shu, Liu; Yue, Lai; Shao-Lin, Yan

    2009-01-01

    The dynamics of a Josephson junction array shunted by a common resistance are investigated by using numerical methods. Coexistence of phase locking and chaos is observed in the system when the resistively and capacitively shunted junction model is adopted. The corresponding parameter ranges for phase locking and chaos are presented. When there are three resistively shunted junctions in the array, chaos is found for the first time and the parameter range for chaos is also presented. According to the theory of Chernikov and Schmidt, when there are four or more junctions in the array, the system exhibits chaotic behavior. Our results indicate that the theory of Chernikov and Schmidt is not exactly appropriate. (condensed matter: electronicstructure, electrical, magnetic, and opticalproperties)

  10. Voltage splay modes and enhanced phase locking in a modified linear Josephson array

    International Nuclear Information System (INIS)

    Harris, E.B.; Garland, J.C.

    1997-01-01

    We analyze a modified linear Josephson-junction array in which additional unbiased junctions are used to greatly enhance phase locking. This geometry exhibits strong correlated behavior, with an external magnetic field tuning the voltage splay angle between adjacent Josephson oscillators. The array displays a coherent in-phase mode for f=(1)/(2), where f is the magnetic frustration, while for 0 p (f)=2aV dc /Φ 0 (1-2f). The locked splay modes are found to be tolerant of critical current disorder approaching 100%. The stability of the array has also been studied by computing Floquet exponents. These exponents are found to be negative for all array lengths, with a 1/N 2 dependence, N being the number of series-connected junctions. copyright 1996 The American Physical Society

  11. Phase-locked, high power, mid-infrared quantum cascade laser arrays

    Science.gov (United States)

    Zhou, W.; Slivken, S.; Razeghi, M.

    2018-04-01

    We demonstrate phase-locked, high power quantum cascade laser arrays, which are combined using a monolithic, tree array multimode interferometer, with emission wavelengths around 4.8 μm. A maximum output power of 15 W was achieved from an eight-element laser array, which has only a slightly higher threshold current density and a similar slope efficiency compared to a Fabry-Perot laser of the same length. Calculated multimode interferometer splitting loss is on the order of 0.27 dB for the in-phase supermode. In-phase supermode operation with nearly ideal behavior is demonstrated over the working current range of the array.

  12. Shot-noise-limited monitoring and phase locking of the motion of a single trapped ion.

    Science.gov (United States)

    Bushev, P; Hétet, G; Slodička, L; Rotter, D; Wilson, M A; Schmidt-Kaler, F; Eschner, J; Blatt, R

    2013-03-29

    We perform a high-resolution real-time readout of the motion of a single trapped and laser-cooled Ba+ ion. By using an interferometric setup, we demonstrate a shot-noise-limited measurement of thermal oscillations with a resolution of 4 times the standard quantum limit. We apply the real-time monitoring for phase control of the ion motion through a feedback loop, suppressing the photon recoil-induced phase diffusion. Because of the spectral narrowing in the phase-locked mode, the coherent ion oscillation is measured with a resolution of about 0.3 times the standard quantum limit.

  13. Phase modulated high density collinear holographic data storage system with phase-retrieval reference beam locking and orthogonal reference encoding.

    Science.gov (United States)

    Liu, Jinpeng; Horimai, Hideyoshi; Lin, Xiao; Huang, Yong; Tan, Xiaodi

    2018-02-19

    A novel phase modulation method for holographic data storage with phase-retrieval reference beam locking is proposed and incorporated into an amplitude-encoding collinear holographic storage system. Unlike the conventional phase retrieval method, the proposed method locks the data page and the corresponding phase-retrieval interference beam together at the same location with a sequential recording process, which eliminates piezoelectric elements, phase shift arrays and extra interference beams, making the system more compact and phase retrieval easier. To evaluate our proposed phase modulation method, we recorded and then recovered data pages with multilevel phase modulation using two spatial light modulators experimentally. For 4-level, 8-level, and 16-level phase modulation, we achieved the bit error rate (BER) of 0.3%, 1.5% and 6.6% respectively. To further improve data storage density, an orthogonal reference encoding multiplexing method at the same position of medium is also proposed and validated experimentally. We increased the code rate of pure 3/16 amplitude encoding method from 0.5 up to 1.0 and 1.5 using 4-level and 8-level phase modulation respectively.

  14. Phase-locking in quantum and classical oscillators: polariton condensates, lasers, and arrays of Josephson junctions

    OpenAIRE

    EASTHAM, PAUL

    2003-01-01

    PUBLISHED We connect three phenomena in which a coherent electromagnetic field could be generated: polariton condensation, phase-locking in arrays of underdamped Josephson junctions, and lasing. All these phenomena have been described using Dicke-type models of spins coupled to a single photon mode. These descriptions may be distinguished by whether the spins are quantum or classical, and whether they are strongly or weakly damped.

  15. A superconducting phase-locked local oscillator for a submillimetre integrated receiver

    International Nuclear Information System (INIS)

    Koshelets, V P; Shitov, S V; Filippenko, L V; Dmitriev, P N; Ermakov, A B; Sobolev, A S; Torgashin, M Yu; Pankratov, A L; Kurin, V V; Yagoubov, P; Hoogeveen, R

    2004-01-01

    Comprehensive measurements of the flux flow oscillator (FFO) radiation linewidth are performed using an integrated harmonic SIS mixer; the FFO linewidth and spectral line profile are compared to a theory. An essential dependence of the FFO linewidth on frequency is found; a possible explanation is proposed. The results of the numerical solution of the perturbed sine-Gordon equation qualitatively confirm this assumption. To optimize the FFO design, the influence of the FFO parameters on the radiation linewidth is studied. A novel FFO design at a moderate current density has resulted in a free-running FFO linewidth of about 10 MHz in the flux flow regime up to 712 GHz, limited only by the gap frequency of Nb. This relatively narrow free-running linewidth (along with implementation of a wide-band phase locking loop system) allows continuous phase locking of the FFO in the wide frequency range of 500-710 GHz. These results are the basis for the development of a 550-650 GHz integrated receiver for the terahertz limb sounder (TELIS) intended for atmosphere study and scheduled to fly on a balloon in 2005. We report here also on the design of the second generation of the phase-locked superconducting integrated receiver chip for TELIS

  16. Spontaneous default mode network phase-locking moderates performance perceptions under stereotype threat.

    Science.gov (United States)

    Forbes, Chad E; Leitner, Jordan B; Duran-Jordan, Kelly; Magerman, Adam B; Schmader, Toni; Allen, John J B

    2015-07-01

    This study assessed whether individual differences in self-oriented neural processing were associated with performance perceptions of minority students under stereotype threat. Resting electroencephalographic activity recorded in white and minority participants was used to predict later estimates of task errors and self-doubt on a presumed measure of intelligence. We assessed spontaneous phase-locking between dipole sources in left lateral parietal cortex (LPC), precuneus/posterior cingulate cortex (P/PCC), and medial prefrontal cortex (MPFC); three regions of the default mode network (DMN) that are integral for self-oriented processing. Results revealed that minorities with greater LPC-P/PCC phase-locking in the theta band reported more accurate error estimations. All individuals experienced less self-doubt to the extent they exhibited greater LPC-MPFC phase-locking in the alpha band but this effect was driven by minorities. Minorities also reported more self-doubt to the extent they overestimated errors. Findings reveal novel neural moderators of stereotype threat effects on subjective experience. Spontaneous synchronization between DMN regions may play a role in anticipatory coping mechanisms that buffer individuals from stereotype threat. © The Author (2014). Published by Oxford University Press. For Permissions, please email: journals.permissions@oup.com.

  17. Phase locking and multiple oscillating attractors for the coupled mammalian clock and cell cycle.

    Science.gov (United States)

    Feillet, Céline; Krusche, Peter; Tamanini, Filippo; Janssens, Roel C; Downey, Mike J; Martin, Patrick; Teboul, Michèle; Saito, Shoko; Lévi, Francis A; Bretschneider, Till; van der Horst, Gijsbertus T J; Delaunay, Franck; Rand, David A

    2014-07-08

    Daily synchronous rhythms of cell division at the tissue or organism level are observed in many species and suggest that the circadian clock and cell cycle oscillators are coupled. For mammals, despite known mechanistic interactions, the effect of such coupling on clock and cell cycle progression, and hence its biological relevance, is not understood. In particular, we do not know how the temporal organization of cell division at the single-cell level produces this daily rhythm at the tissue level. Here we use multispectral imaging of single live cells, computational methods, and mathematical modeling to address this question in proliferating mouse fibroblasts. We show that in unsynchronized cells the cell cycle and circadian clock robustly phase lock each other in a 1:1 fashion so that in an expanding cell population the two oscillators oscillate in a synchronized way with a common frequency. Dexamethasone-induced synchronization reveals additional clock states. As well as the low-period phase-locked state there are distinct coexisting states with a significantly higher period clock. Cells transition to these states after dexamethasone synchronization. The temporal coordination of cell division by phase locking to the clock at a single-cell level has significant implications because disordered circadian function is increasingly being linked to the pathogenesis of many diseases, including cancer.

  18. The Design of Phase-Locked-Loop Circuit for Precision Capacitance Micrometer

    Directory of Open Access Journals (Sweden)

    Li Shujie

    2016-01-01

    Full Text Available High precision non-contact micrometer is normally divided into three categories: inductance micrometer, capacitance micrometer and optical interferometer micrometer. The capacitance micrometer is widely used because it has high performance to price ratio. With the improvement of automation level, precision of capacitance micrometer is required higher and higher. Generally, capacitance micrometer consists of the capacitance sensor, capacitance/voltage conversion circuit, and modulation and demodulation circuits. However, due to the existing of resistors, capacitors and other components in the circuit, the phase shift of the carrier signal and the modulated signal might occur. In this case, the specific value of phase shift cannot be determined. Therefore, error caused by the phase shift cannot be eliminated. This will reduce the accuracy of micrometer. In this design, in order to eliminate the impact of the phase shift, the phase-locked-loop (PLL circuit is employed. Through the experiment, the function of tracking the input signal phase and frequency is achieved by the phase-locked-loop circuit. This signal processing method can also be applied to tuber electrical resistance tomography system and other precision measurement circuit.

  19. Coherent optical communication detection device based on modified balanced optical phase-locked loop

    Science.gov (United States)

    Zhang, Bo; Sun, Jianfeng; Xu, Mengmeng; Li, Guangyuan; Zhang, Guo; Lao, Chenzhe; He, Hongyu; Lu, Zhiyong

    2017-08-01

    In the field of satellite communication, space laser communication technology is famous for its high communication rate, good confidentiality, small size, low power consumption and so on. The design of coherent optical communication detection device based on modified balanced optical phase-locked loop (OPLL) is presented in the paper. It combined by local oscillator beam, modulator, voltage controlled oscillator, signal beam, optical filter, 180 degree hybrid, balanced detector, loop filter and signal receiver. Local oscillator beam and voltage controlled oscillator trace the phase variation of signal beam simultaneously. That taking the advantage of voltage controlled oscillator which responses sensitively and tunable local oscillator laser source with large tuning range can trace the phase variation of signal beam rapidly and achieve phase locking. The demand of the phase deviation is very low, and the system is easy to adjust. When the transmitter transmits the binary phase shift keying (BPSK) signal, the receiver can demodulate the baseband signal quickly, which has important significance for the free space coherent laser communication.

  20. Simulation Study Using an Injection Phase-locked Magnetron as an Alternative Source for SRF Accelerators

    Energy Technology Data Exchange (ETDEWEB)

    Wang, Haipeng [Thomas Jefferson National Accelerator Facility, Newport News, VA (United States); Plawski, Tomasz E. [Thomas Jefferson National Accelerator Facility, Newport News, VA (United States); Rimmer, Robert A. [Thomas Jefferson National Accelerator Facility, Newport News, VA (United States)

    2015-09-01

    As a drop-in replacement for the CEBAF CW klystron system, a 1497 MHz, CW-type high-efficiency magnetron using injection phase lock and amplitude variation is attractive. Amplitude control using magnetic field trimming and anode voltage modulation has been studied using analytical models and MATLAB/Simulink simulations. Since the 1497 MHz magnetron has not been built yet, previously measured characteristics of a 2.45GHz cooker magnetron are used as reference. The results of linear responses to the amplitude and phase control of a superconducting RF (SRF) cavity, and the expected overall benefit for the current CEBAF and future MEIC RF systems are presented in this paper.

  1. High-accuracy resolver-to-digital conversion via phase locked loop based on PID controller

    Science.gov (United States)

    Li, Yaoling; Wu, Zhong

    2018-03-01

    The problem of resolver-to-digital conversion (RDC) is transformed into the problem of angle tracking control, and a phase locked loop (PLL) method based on PID controller is proposed in this paper. This controller comprises a typical PI controller plus an incomplete differential which can avoid the amplification of higher-frequency noise components by filtering the phase detection error with a low-pass filter. Compared with conventional ones, the proposed PLL method makes the converter a system of type III and thus the conversion accuracy can be improved. Experimental results demonstrate the effectiveness of the proposed method.

  2. Towards a phase-locked superconducting integrated receiver: prospects and limitations

    DEFF Research Database (Denmark)

    Koshelets, V.P.; Shitov, S.V.; Dmitriev, P.N.

    2002-01-01

    Presently a Josephson flux flow oscillator (FFO) appears to be the most developed superconducting on-chip local oscillator for integrated submillimeter-wave SIS receivers. The feasibility of phase locking the FFO to an external reference oscillator at all frequencies of interest has to be proven...... compared to theory in order to optimize the FFO design. The influence of FFO parameters on radiation linewidth, particularly the effect of the differential resistances associated both with the bias current and the applied magnetic field, has been studied. Two integrated receiver concepts with phase...

  3. Voltage splay modes and enhanced phase locking in a modified linear Josephson array

    Science.gov (United States)

    Harris, E. B.; Garland, J. C.

    1997-02-01

    We analyze a modified linear Josephson-junction array in which additional unbiased junctions are used to greatly enhance phase locking. This geometry exhibits strong correlated behavior, with an external magnetic field tuning the voltage splay angle between adjacent Josephson oscillators. The array displays a coherent in-phase mode for f=, where f is the magnetic frustration, while for 0tolerant of critical current disorder approaching 100%. The stability of the array has also been studied by computing Floquet exponents. These exponents are found to be negative for all array lengths, with a 1/N2 dependence, N being the number of series-connected junctions.

  4. Transverse phase-locking in fully frustrated Josephson junction arrays: A new type of fractional giant steps

    International Nuclear Information System (INIS)

    Marconi, Veronica I.; Kolton, Alejandro B.; Dominguez, Daniel; Gronbech-Jensen, Niels

    2003-05-01

    We study, analytically and numerically, phase locking of driven vortex lattices in fully-frustrated Josephson junction arrays at zero temperature. We consider the case when an ac current is applied perpendicular to a dc current. We observe phase locking, steps in the current-voltage characteristics, with a dependence on external ac-drive amplitude and frequency qualitatively different from the Shapiro steps, observed when the ac and dc currents are applied in parallel. Further, the critical current increases with increasing transverse ac-drive amplitude, while it decreases for longitudinal ac-drive. The critical current and the phase-locked current step width, increase quadratically with (small) amplitudes of the ac-drive. For larger amplitudes of the transverse ac-signal, we find windows where the critical current is hysteretic, and windows where phase locking is suppressed due to dynamical instabilities. We characterize the dynamical states around the phase-locking interference condition in the IV curve with voltage noise, Lyapunov exponents and Poincare sections. We find that zero temperature phase-locking behavior in large fully frustrated arrays is well described by an effective four plaquette model. (author)

  5. Packaged semiconductor laser optical phase locked loop for photonic generation, processing and transmission of microwave signals

    DEFF Research Database (Denmark)

    Langley, L.N.; Elkin, M.D.; Edege, C.

    1999-01-01

    In this paper, we present the first fully packaged semiconductor laser optical phase-locked loop (OPLL) microwave photonic transmitter. The transmitter is based on semiconductor lasers that are directly phase locked without the use of any other phase noise-reduction mechanisms. In this transmitter......, the lasers have a free-running summed linewidth of 6 MHz and the OPLL has a feedback bandwidth of 70 MHz, A state-of-the-art performance is obtained, with a total phase-error variance of 0.05 rad(2) (1-GHz bandwidth) and a carrier phase-error variance of 7x10(-4) rad(2) in a 15-MHz bandwidth. Carriers...... are generated in the range of 7-14 GHz. The OPLL transmitter has been fully packaged for practical use in field trials. This is the first time this type of transmitter has been fabricated in a packaged state which is a significant advance on the route to practical application....

  6. Power Based Phase-Locked Loop Under Adverse Conditions with Moving Average Filter for Single-Phase System

    Directory of Open Access Journals (Sweden)

    Menxi Xie

    2017-06-01

    Full Text Available High performance synchronization methord is citical for grid connected power converter. For single-phase system, power based phase-locked loop(pPLL uses a multiplier as phase detector(PD. As single-phase grid voltage is distorted, the phase error information contains ac disturbances oscillating at integer multiples of fundamental frequency which lead to detection error. This paper presents a new scheme based on moving average filter(MAF applied in-loop of pPLL. The signal characteristic of phase error is dissussed in detail. A predictive rule is adopted to compensate the delay induced by MAF, thus achieving fast dynamic response. In the case of frequency deviate from nomimal, estimated frequency is fed back to adjust the filter window length of MAF and buffer size of predictive rule. Simulation and experimental results show that proposed PLL achieves good performance under adverse grid conditions.

  7. Be discs in coplanar circular binaries: Phase-locked variations of emission lines

    Science.gov (United States)

    Panoglou, Despina; Faes, Daniel M.; Carciofi, Alex C.; Okazaki, Atsuo T.; Baade, Dietrich; Rivinius, Thomas; Borges Fernandes, Marcelo

    2018-01-01

    In this paper, we present the first results of radiative transfer calculations on decretion discs of binary Be stars. A smoothed particle hydrodynamics code computes the structure of Be discs in coplanar circular binary systems for a range of orbital and disc parameters. The resulting disc configuration consists of two spiral arms, and this can be given as input into a Monte Carlo code, which calculates the radiative transfer along the line of sight for various observational coordinates. Making use of the property of steady disc structure in coplanar circular binaries, observables are computed as functions of the orbital phase. Some orbital-phase series of line profiles are given for selected parameter sets under various viewing angles, to allow comparison with observations. Flat-topped profiles with and without superimposed multiple structures are reproduced, showing, for example, that triple-peaked profiles do not have to be necessarily associated with warped discs and misaligned binaries. It is demonstrated that binary tidal effects give rise to phase-locked variability of the violet-to-red (V/R) ratio of hydrogen emission lines. The V/R ratio exhibits two maxima per cycle; in certain cases those maxima are equal, leading to a clear new V/R cycle every half orbital period. This study opens a way to identifying binaries and to constraining the parameters of binary systems that exhibit phase-locked variations induced by tidal interaction with a companion star.

  8. A fully-differential phase-locked loop frequency synthesizer for 60-GHz wireless communication

    International Nuclear Information System (INIS)

    Kuang Lixue; Chi Baoyong; Chen Lei; Wang Zhihua; Jia Wen

    2014-01-01

    A 40-GHz phase-locked loop (PLL) frequency synthesizer for 60-GHz wireless communication applications is presented. The electrical characteristics of the passive components in the VCO and LO buffers are accurately extracted with an electromagnetic simulator HFSS. A differential tuning technique is utilized in the voltage controlled oscillator (VCO) to achieve higher common-mode noise rejection and better phase noise performance. The VCO and the divider chain are powered by a 1.0 V supply while the phase-frequency detector (PFD) and the charge pump (CP) are powered by a 2.5 V supply to improve the linearity. The measurement results show that the total frequency locking range of the frequency synthesizer is from 37 to 41 GHz, and the phase noise from a 40 GHz carrier is −97.2 dBc/Hz at 1 MHz offset. Implemented in 65 nm CMOS, the synthesizer consumes a DC power of 62 mW, including all the buffers. (semiconductor integrated circuits)

  9. A fully-differential phase-locked loop frequency synthesizer for 60-GHz wireless communication

    Science.gov (United States)

    Lixue, Kuang; Baoyong, Chi; Lei, Chen; Wen, Jia; Zhihua, Wang

    2014-12-01

    A 40-GHz phase-locked loop (PLL) frequency synthesizer for 60-GHz wireless communication applications is presented. The electrical characteristics of the passive components in the VCO and LO buffers are accurately extracted with an electromagnetic simulator HFSS. A differential tuning technique is utilized in the voltage controlled oscillator (VCO) to achieve higher common-mode noise rejection and better phase noise performance. The VCO and the divider chain are powered by a 1.0 V supply while the phase-frequency detector (PFD) and the charge pump (CP) are powered by a 2.5 V supply to improve the linearity. The measurement results show that the total frequency locking range of the frequency synthesizer is from 37 to 41 GHz, and the phase noise from a 40 GHz carrier is -97.2 dBc/Hz at 1 MHz offset. Implemented in 65 nm CMOS, the synthesizer consumes a DC power of 62 mW, including all the buffers.

  10. Noise-shaping all-digital phase-locked loops modeling, simulation, analysis and design

    CERN Document Server

    Brandonisio, Francesco

    2014-01-01

    This book presents a novel approach to the analysis and design of all-digital phase-locked loops (ADPLLs), technology widely used in wireless communication devices. The authors provide an overview of ADPLL architectures, time-to-digital converters (TDCs) and noise shaping. Realistic examples illustrate how to analyze and simulate phase noise in the presence of sigma-delta modulation and time-to-digital conversion. Readers will gain a deep understanding of ADPLLs and the central role played by noise-shaping. A range of ADPLL and TDC architectures are presented in unified manner. Analytical and simulation tools are discussed in detail. Matlab code is included that can be reused to design, simulate and analyze the ADPLL architectures that are presented in the book.   • Discusses in detail a wide range of all-digital phase-locked loops architectures; • Presents a unified framework in which to model time-to-digital converters for ADPLLs; • Explains a procedure to predict and simulate phase noise in oscil...

  11. A digital, constant-frequency pulsed phase-locked-loop instrument for real-time, absolute ultrasonic phase measurements

    Science.gov (United States)

    Haldren, H. A.; Perey, D. F.; Yost, W. T.; Cramer, K. E.; Gupta, M. C.

    2018-05-01

    A digitally controlled instrument for conducting single-frequency and swept-frequency ultrasonic phase measurements has been developed based on a constant-frequency pulsed phase-locked-loop (CFPPLL) design. This instrument uses a pair of direct digital synthesizers to generate an ultrasonically transceived tone-burst and an internal reference wave for phase comparison. Real-time, constant-frequency phase tracking in an interrogated specimen is possible with a resolution of 0.000 38 rad (0.022°), and swept-frequency phase measurements can be obtained. Using phase measurements, an absolute thickness in borosilicate glass is presented to show the instrument's efficacy, and these results are compared to conventional ultrasonic pulse-echo time-of-flight (ToF) measurements. The newly developed instrument predicted the thickness with a mean error of -0.04 μm and a standard deviation of error of 1.35 μm. Additionally, the CFPPLL instrument shows a lower measured phase error in the absence of changing temperature and couplant thickness than high-resolution cross-correlation ToF measurements at a similar signal-to-noise ratio. By showing higher accuracy and precision than conventional pulse-echo ToF measurements and lower phase errors than cross-correlation ToF measurements, the new digitally controlled CFPPLL instrument provides high-resolution absolute ultrasonic velocity or path-length measurements in solids or liquids, as well as tracking of material property changes with high sensitivity. The ability to obtain absolute phase measurements allows for many new applications than possible with previous ultrasonic pulsed phase-locked loop instruments. In addition to improved resolution, swept-frequency phase measurements add useful capability in measuring properties of layered structures, such as bonded joints, or materials which exhibit non-linear frequency-dependent behavior, such as dispersive media.

  12. A multiple-pass ring oscillator based dual-loop phase-locked loop

    International Nuclear Information System (INIS)

    Chen Danfeng; Ren Junyan; Deng Jingjing; Li Wei; Li Ning

    2009-01-01

    A dual-loop phase-locked loop (PLL) for wideband operation is proposed. The dual-loop architecture combines a coarse-tuning loop with a fine-tuning one, enabling a wide tuning range and low voltage-controlled oscillator (VCO) gain without poisoning phase noise and reference spur suppression performance. An analysis of the phase noise and reference spur of the dual-loop PLL is emphasized. A novel multiple-pass ring VCO is designed for the dual-loop application. It utilizes both voltage-control and current-control simultaneously in the delay cell. The PLL is fabricated in Jazz 0.18-μm RF CMOS technology. The measured tuning range is from 4.2 to 5.9 GHz. It achieves a low phase noise of -99 dBc/Hz - 1 MHz offset from a 5.5 GHz carrier.

  13. A multiple-pass ring oscillator based dual-loop phase-locked loop

    Energy Technology Data Exchange (ETDEWEB)

    Chen Danfeng; Ren Junyan; Deng Jingjing; Li Wei; Li Ning, E-mail: dfchen@fudan.edu.c [State Key Laboratory of ASIC and System, Fudan University, Shanghai 201203 (China)

    2009-10-15

    A dual-loop phase-locked loop (PLL) for wideband operation is proposed. The dual-loop architecture combines a coarse-tuning loop with a fine-tuning one, enabling a wide tuning range and low voltage-controlled oscillator (VCO) gain without poisoning phase noise and reference spur suppression performance. An analysis of the phase noise and reference spur of the dual-loop PLL is emphasized. A novel multiple-pass ring VCO is designed for the dual-loop application. It utilizes both voltage-control and current-control simultaneously in the delay cell. The PLL is fabricated in Jazz 0.18-{mu}m RF CMOS technology. The measured tuning range is from 4.2 to 5.9 GHz. It achieves a low phase noise of -99 dBc/Hz - 1 MHz offset from a 5.5 GHz carrier.

  14. Multi-Phase Sub-Sampling Fractional-N PLL with soft loop switching for fast robust locking

    NARCIS (Netherlands)

    Liao, Dongyi; Dai, FA Foster; Nauta, Bram; Klumperink, Eric A.M.

    2017-01-01

    This paper presents a low phase noise sub-sampling PLL (SSPLL) with multi-phase outputs. Automatic soft switching between the sub-sampling phase loop and frequency loop is proposed to improve robustness against perturbations and interferences that may cause a traditional SSPLL to lose lock. A

  15. Optical Phase Recovery and Locking in a PPM Laser Communication Link

    Science.gov (United States)

    Aveline, David C.; Yu, Nan; Farr, William H.

    2012-01-01

    Free-space optical communication holds great promise for future space missions requiring high data rates. For data communication in deep space, the current architecture employs pulse position modulation (PPM). In this scheme, the light is transmitted and detected as pulses within an array of time slots. While the PPM method is efficient for data transmission, the phase of the laser light is not utilized. The phase coherence of a PPM optical signal has been investigated with the goal of developing a new laser communication and ranging scheme that utilizes optical coherence within the established PPM architecture and photon-counting detection (PCD). Experimental measurements of a PPM modulated optical signal were conducted, and modeling code was developed to generate random PPM signals and simulate spectra via FFT (Fast Fourier Transform) analysis. The experimental results show very good agreement with the simulations and confirm that coherence is preserved despite modulation with high extinction ratios and very low duty cycles. A real-time technique has been developed to recover the phase information through the mixing of a PPM signal with a frequency-shifted local oscillator (LO). This mixed signal is amplified, filtered, and integrated to generate a voltage proportional to the phase of the modulated signal. By choosing an appropriate time constant for integration, one can maintain a phase lock despite long dark times between consecutive pulses with low duty cycle. A proof-of-principle demonstration was first achieved with an RF-based PPM signal and test setup. With the same principle method, an optical carrier within a PPM modulated laser beam could also be tracked and recovered. A reference laser was phase-locked to an independent pulsed laser signal with low-duty-cycle pseudo-random PPM codes. In this way, the drifting carrier frequency in the primary laser source is tracked via its phase change in the mixed beat note, while the corresponding voltage feedback

  16. Effects of Density-Dependent Quark Mass on Phase Diagram of Color-Flavor-Locked Quark Matter

    Institute of Scientific and Technical Information of China (English)

    2006-01-01

    Considering the density dependence of quark mass, we investigate the phase transition between the (unpaired) strange quark matter and the color-flavor-locked matter, which are supposed to be two candidates for the ground state of strongly interacting matter. We find that if the current mass of strange quark ms is small, the strange quark matter remains stable unless the baryon density is very high. If ms is large, the phase transition from the strange quark matter to the color-flavor-locked matter in particular to its gapless phase is found to be different from the results predicted by previous works. A complicated phase diagram of three-flavor quark matter is presented, in which the color-flavor-locked phase region is suppressed for moderate densities.

  17. The Design of a High Speed Low Power Phase Locked Loop

    CERN Document Server

    Liu, Tiankuan; Hou, Suen; Liang, Zhihua; Liu, Chonghan; Su, Da-Shung; Teng, Ping-Kun; Xiang, Annie C; Ye, Jingbo

    2009-01-01

    The upgrade of the ATLAS Liquid Argon Calorimeter readout system calls for the development of radiation tolerant, high speed and low power serializer ASIC. We have designed a phase locked loop using a commercial 0.25-μm Silicon-on- Sapphire (SoS) CMOS technology. Post-layout simulation indicates that tuning range is 3.79 – 5.01 GHz and power consumption is 104 mW. The PLL has been submitted for fabrication. The design and simulation results are presented.

  18. Relativistic Hydrodynamics of Color-Flavor Locking Phase with Spontaneous Symmetry Breaking

    Institute of Scientific and Technical Information of China (English)

    ZHANG Sun; WANG Fan

    2004-01-01

    We study the hydrodynamics of color-flavor locking phase of three flavors of light quarks in high density QCD with spontaneous symmetry breaking. The basic hydrodynamic equations are presented based on the Poisson bracket method and the Goldstone phonon and the thermo phonon are compared. The dissipative equations are constructed in the frame of the first-order theory and all the transport coefficients are also defined, which could be looked on as the general case including the Landau's theory and the Eckart's theory

  19. Forced phase-locked response of a nonlinear system with time delay after Hopf bifurcation

    International Nuclear Information System (INIS)

    Ji, J.C.; Hansen, Colin H.

    2005-01-01

    The trivial equilibrium of a nonlinear autonomous system with time delay may become unstable via a Hopf bifurcation of multiplicity two, as the time delay reaches a critical value. This loss of stability of the equilibrium is associated with two coincident pairs of complex conjugate eigenvalues crossing the imaginary axis. The resultant dynamic behaviour of the corresponding nonlinear non-autonomous system in the neighbourhood of the Hopf bifurcation is investigated based on the reduction of the infinite-dimensional problem to a four-dimensional centre manifold. As a result of the interaction between the Hopf bifurcating periodic solutions and the external periodic excitation, a primary resonance can occur in the forced response of the system when the forcing frequency is close to the Hopf bifurcating periodic frequency. The method of multiple scales is used to obtain four first-order ordinary differential equations that determine the amplitudes and phases of the phase-locked periodic solutions. The first-order approximations of the periodic solutions are found to be in excellent agreement with those obtained by direct numerical integration of the delay-differential equation. It is also found that the steady state solutions of the nonlinear non-autonomous system may lose their stability via either a pitchfork or Hopf bifurcation. It is shown that the primary resonance response may exhibit symmetric and asymmetric phase-locked periodic motions, quasi-periodic motions, chaotic motions, and coexistence of two stable motions

  20. Toward robust phase-locking in Melibe swim central pattern generator models

    Science.gov (United States)

    Jalil, Sajiya; Allen, Dane; Youker, Joseph; Shilnikov, Andrey

    2013-12-01

    Small groups of interneurons, abbreviated by CPG for central pattern generators, are arranged into neural networks to generate a variety of core bursting rhythms with specific phase-locked states, on distinct time scales, which govern vital motor behaviors in invertebrates such as chewing and swimming. These movements in lower level animals mimic motions of organs in higher animals due to evolutionarily conserved mechanisms. Hence, various neurological diseases can be linked to abnormal movement of body parts that are regulated by a malfunctioning CPG. In this paper, we, being inspired by recent experimental studies of neuronal activity patterns recorded from a swimming motion CPG of the sea slug Melibe leonina, examine a mathematical model of a 4-cell network that can plausibly and stably underlie the observed bursting rhythm. We develop a dynamical systems framework for explaining the existence and robustness of phase-locked states in activity patterns produced by the modeled CPGs. The proposed tools can be used for identifying core components for other CPG networks with reliable bursting outcomes and specific phase relationships between the interneurons. Our findings can be employed for identifying or implementing the conditions for normal and pathological functioning of basic CPGs of animals and artificially intelligent prosthetics that can regulate various movements.

  1. A digital optical phase-locked loop for diode lasers based on field programmable gate array

    Energy Technology Data Exchange (ETDEWEB)

    Xu Zhouxiang; Zhang Xian; Huang Kaikai; Lu Xuanhui [Physics Department, Zhejiang University, Hangzhou, 310027 (China)

    2012-09-15

    We have designed and implemented a highly digital optical phase-locked loop (OPLL) for diode lasers in atom interferometry. The three parts of controlling circuit in this OPLL, including phase and frequency detector (PFD), loop filter and proportional integral derivative (PID) controller, are implemented in a single field programmable gate array chip. A structure type compatible with the model MAX9382/MCH12140 is chosen for PFD and pipeline and parallelism technology have been adapted in PID controller. Especially, high speed clock and twisted ring counter have been integrated in the most crucial part, the loop filter. This OPLL has the narrow beat note line width below 1 Hz, residual mean-square phase error of 0.14 rad{sup 2} and transition time of 100 {mu}s under 10 MHz frequency step. A main innovation of this design is the completely digitalization of the whole controlling circuit in OPLL for diode lasers.

  2. FPGA implementation of self organizing map with digital phase locked loops.

    Science.gov (United States)

    Hikawa, Hiroomi

    2005-01-01

    The self-organizing map (SOM) has found applicability in a wide range of application areas. Recently new SOM hardware with phase modulated pulse signal and digital phase-locked loops (DPLLs) has been proposed (Hikawa, 2005). The system uses the DPLL as a computing element since the operation of the DPLL is very similar to that of SOM's computation. The system also uses square waveform phase to hold the value of the each input vector element. This paper discuss the hardware implementation of the DPLL SOM architecture. For effective hardware implementation, some components are redesigned to reduce the circuit size. The proposed SOM architecture is described in VHDL and implemented on field programmable gate array (FPGA). Its feasibility is verified by experiments. Results show that the proposed SOM implemented on the FPGA has a good quantization capability, and its circuit size very small.

  3. A digital optical phase-locked loop for diode lasers based on field programmable gate array

    Science.gov (United States)

    Xu, Zhouxiang; Zhang, Xian; Huang, Kaikai; Lu, Xuanhui

    2012-09-01

    We have designed and implemented a highly digital optical phase-locked loop (OPLL) for diode lasers in atom interferometry. The three parts of controlling circuit in this OPLL, including phase and frequency detector (PFD), loop filter and proportional integral derivative (PID) controller, are implemented in a single field programmable gate array chip. A structure type compatible with the model MAX9382/MCH12140 is chosen for PFD and pipeline and parallelism technology have been adapted in PID controller. Especially, high speed clock and twisted ring counter have been integrated in the most crucial part, the loop filter. This OPLL has the narrow beat note line width below 1 Hz, residual mean-square phase error of 0.14 rad2 and transition time of 100 μs under 10 MHz frequency step. A main innovation of this design is the completely digitalization of the whole controlling circuit in OPLL for diode lasers.

  4. Phase locked 270-440 GHz local oscillator based on flux flow in long Josephson tunnel junctions

    DEFF Research Database (Denmark)

    Koshelets, V.P.; Shitov, S.V.; Filippenko, L.V.

    2000-01-01

    The combination of narrow linewidth and wide band tunability makes the Josephson flux flow oscillator (FFO) a perfect on-chip local oscillator for integrated sub-mm wave receivers for, e.g., spectral radio astronomy. The feasibility of phase locking the FFO to an external reference oscillator......-running tunnel junction. The results of residual FFO phase noise measurements are also presented. Finally, we propose a single-chip fully superconductive receiver with two superconductor–insulator–superconductor mixers and an integrated phase-locked loop. ©2000 American Institute of Physics....

  5. From perception to action: phase-locked gamma oscillations correlate with reaction times in a speeded response task

    Directory of Open Access Journals (Sweden)

    Körner Ursula

    2007-04-01

    Full Text Available Abstract Background Phase-locked gamma oscillations have so far mainly been described in relation to perceptual processes such as sensation, attention or memory matching. Due to its very short latency (≈90 ms such oscillations are a plausible candidate for very rapid integration of sensory and motor processes. Results We measured EEG in 13 healthy participants in a speeded reaction task. Participants had to press a button as fast as possible whenever a visual stimulus was presented. The stimulus was always identical and did not have to be discriminated from other possible stimuli. In trials in which the participants showed a fast response, a slow negative potential over central electrodes starting approximately 800 ms before the response and highly phase-locked gamma oscillations over central and posterior electrodes between 90 and 140 ms after the stimulus were observed. In trials in which the participants showed a slow response, no slow negative potential was observed and phase-locked gamma oscillations were significantly reduced. Furthermore, for slow response trials the phase-locked gamma oscillations were significantly delayed with respect to fast response trials. Conclusion These results indicate the relevance of phase-locked gamma oscillations for very fast (not necessarily detailed integration processes.

  6. High fidelity phase locked PIV measurements analysing the flow fields surrounding an oscillating piezoelectric fan

    International Nuclear Information System (INIS)

    Jeffers, Nicholas; Nolan, Kevin; Stafford, Jason; Donnelly, Brian

    2014-01-01

    Piezoelectric fans have been studied extensively and are seen as a promising technology for thermal management due to their ability to provide quiet, reliable cooling with low power consumption. The fluid mechanics of an unconfined piezoelectric fan are complex which is why the majority of the literature to date confines the fan in an attempt to simplify the flow field. This paper investigates the fluid mechanics of an unconfined fan operating in its first vibration frequency mode. The piezoelectric fan used in this study measures 12.7 mm × 70 mm and resonates at 92.5 Hz in air. A custom built experimental facility was developed to capture the fan's flow field using phase locked Particle Image Velocimetry (PIV). The phase locked PIV results are presented in terms of vorticity and show the formation of a horse shoe vortex. A three dimensional A2 criterion constructed from interpolated PIV measurements was used to identify the vortex core in the vicinity of the fan. This analysis was used to clearly identify the formation of a horse shoe vortex that turns into a hairpin vortex before it breaks up due to a combination of vortex shedding and flow along the fan blade. The results presented in this paper contribute to both the fluid dynamics and heat transfer literature concerning first mode fan oscillation.

  7. Ratchet Effects, Negative Mobility, and Phase Locking for Skyrmions on Periodic Substrates

    Science.gov (United States)

    Reichhardt, Charles; Ray, Dipanjan; Olson Reichhardt, Cynthia

    We examine the dynamics of skyrmions interacting with 1D and 2D periodic substrates in the presence of dc and ac drives. We find that the Magnus term strongly affects the skyrmion dynamics and that new kinds of phenomena can occur which are absent for overdamped ac and dc driven particles interacting with similar substrates. We show that it is possible to realize a Magnus induced ratchet for skyrmions interacting with an asymmetric potential, where the application of an ac drive can produce quantized dc motion of the skyrmions even when the ac force is perpendicular to the substrate asymmetry direction. For symmetric substrates it is also possible to achieve a negative mobility effect where the net skyrmion motion runs counter to an applied dc drive. Here, as a function of increasing dc drive, the velocity-force curves show a series of locking phases that have different features from the classic Shapiro steps found in overdamped systems. In the phase locking and ratcheting states, the skyrmions undergo intricate 2D orbits induced by the Magnus term.

  8. A Critical Examination of Frequency-Fixed Second-Order Generalized Integrator-Based Phase-Locked Loops

    DEFF Research Database (Denmark)

    Golestan, Saeed; Mousazadeh Mousavi, Seyyed-Yousef; Guerrero, Josep M.

    2017-01-01

    The implementation of a large number of single-phase phase-locked loops (PLLs) involves creating a fictitious quadrature signal. A popular approach for this purpose is using a second-order generalized integrator-based quadrature signal generator (SOGIQSG) because it results in an acceptable speed......-based PLLs (FFSOGI-PLLs) to highlight their real advantages and disadvantages....

  9. Time-invariant PT product and phase locking in PT -symmetric lattice models

    Science.gov (United States)

    Joglekar, Yogesh N.; Onanga, Franck Assogba; Harter, Andrew K.

    2018-01-01

    Over the past decade, non-Hermitian, PT -symmetric Hamiltonians have been investigated as candidates for both a fundamental, unitary, quantum theory and open systems with a nonunitary time evolution. In this paper, we investigate the implications of the former approach in the context of the latter. Motivated by the invariance of the PT (inner) product under time evolution, we discuss the dynamics of wave-function phases in a wide range of PT -symmetric lattice models. In particular, we numerically show that, starting with a random initial state, a universal, gain-site location dependent locking between wave-function phases at adjacent sites occurs in the PT -symmetry-broken region. Our results pave the way towards understanding the physically observable implications of time invariants in the nonunitary dynamics produced by PT -symmetric Hamiltonians.

  10. A Unified Impedance Model of Voltage-Source Converters with Phase-Locked Loop Effect

    DEFF Research Database (Denmark)

    Wang, Xiongfei; Harnefors, Lennart; Blaabjerg, Frede

    2016-01-01

    This paper proposes a unified impedance model for analyzing the effect of Phase-Locked Loop (PLL) on the stability of grid-connected voltage-source converters. In the approach, the dq-frame impedance model is transformed into the stationary αβ-frame by means of complex transfer functions...... and complex space vectors, which not only predicts the stability impact of the PLL, but reveals also its frequency coupling effect in the phase domain. Thus, the impedance models previously developed in the different domains can be unified. Moreover, the impedance shaping effects of PLL are structurally...... characterized for the current control in the rotating dq-frame and the stationary αβ-frame. Case studies based on the unified impedance model are presented, which are then verified in the time-domain simulations and experiments. The results closely correlate with the impedance-based analysis....

  11. Externally Phase-Locked Flux Flow Oscillator for Submm Integrated Receivers; Achievements and Limitations

    DEFF Research Database (Denmark)

    Koshelets, V. P.; Shitov, S. V.; Dmitriev, P. N.

    2003-01-01

    A Josephson Flux Flow Oscillator (FFO) is the most developed superconducting local oscillator for integration with an SIS mixer in a single-chip submm-wave receiver. Recently, using a new FFO design, a free-running linewidth less than or equal to10 MHz has been measured in the frequency range up...... to 712 GHz, limited only by the gap frequency of Nb. This enabled us to phase lock the FFO in the frequency range 500-712 GHz where continuous frequency tuning is possible; resulting in an absolute FFO phase noise as low as -80 dBc at 707 GHz. Comprehensive measurements of the FFO radiation linewidth...... have been performed using an integrated SIS harmonic mixer. The influence of FFO parameters on radiation linewidth, particularly the effect of the differential resistances associated both with the bias current and the applied magnetic field has been studied in order to further optimize the FFO design...

  12. Virtual unit delay for digital frequency adaptive T/4 delay phase-locked loop system

    DEFF Research Database (Denmark)

    Yang, Yongheng; Zhou, Keliang; Blaabjerg, Frede

    2016-01-01

    /processor with a fixed sampling rate considering the cost and complexity, where the number of unit delays that have been adopted should be an integer. For instance, in conventional digital control systems, a single-phase T/4 Delay Phase-Locked Loop (PLL) system takes 50 unit delays (i.e., in a 50-Hz system...... Delay PLL system should be done in its implementation. This process will result in performance degradation in the digital control system, as the exactly required number of delays is not realized. Hence, in this paper, a Virtual Unit Delay (VUD) has been proposed to address such challenges to the digital......Digital micro-controllers/processors enable the cost-effective control of grid-connected power converter systems in terms of system monitoring, signal processing (e.g., grid synchronization), control (e.g., grid current and voltage control), etc. Normally, the control is implemented in a micro-controller...

  13. Hopf bifurcation and chaos in a third-order phase-locked loop

    Science.gov (United States)

    Piqueira, José Roberto C.

    2017-01-01

    Phase-locked loops (PLLs) are devices able to recover time signals in several engineering applications. The literature regarding their dynamical behavior is vast, specifically considering that the process of synchronization between the input signal, coming from a remote source, and the PLL local oscillation is robust. For high-frequency applications it is usual to increase the PLL order by increasing the order of the internal filter, for guarantying good transient responses; however local parameter variations imply structural instability, thus provoking a Hopf bifurcation and a route to chaos for the phase error. Here, one usual architecture for a third-order PLL is studied and a range of permitted parameters is derived, providing a rule of thumb for designers. Out of this range, a Hopf bifurcation appears and, by increasing parameters, the periodic solution originated by the Hopf bifurcation degenerates into a chaotic attractor, therefore, preventing synchronization.

  14. Analysis of Middle Frequency Resonance in DFIG System Considering Phase Locked Loop

    DEFF Research Database (Denmark)

    Song, Yipeng; Blaabjerg, Frede

    2018-01-01

    compensated weak network. Besides these two resonances, a Middle Frequency Resonance (MFR) between 200 Hz and 800 Hz may appear when the Phase Locked Loop (PLL) with fast control dynamics is applied. In order to analyze the MFR, the DFIG system impedance considering the PLL is studied based on the Vector...... Oriented Control (VOC) strategy in Rotor Side Converter (RSC) and Grid Side Converter (GSC). On the basis of the established impedance modeling of the DFIG system, it is found that the PLL with fast control dynamics may result in the occurrence of MFR due to a decreasing phase margin. The simulation...... results of both a 7.5 kW small scale DFIG system and a 2 MW large scale DFIG system are provided to validate the theoretical analysis of the MFR....

  15. Phase locked multiple rings in the radiation pressure ion acceleration process

    Science.gov (United States)

    Wan, Y.; Hua, J. F.; Pai, C.-H.; Li, F.; Wu, Y. P.; Lu, W.; Zhang, C. J.; Xu, X. L.; Joshi, C.; Mori, W. B.

    2018-04-01

    Laser contrast plays a crucial role for obtaining high quality ion beams in the radiation pressure ion acceleration (RPA) process. Through one- and two-dimensional particle-in-cell (PIC) simulations, we show that a plasma with a bi-peak density profile can be produced from a thin foil on the effects of a picosecond prepulse, and it can then lead to distinctive modulations in the ion phase space (phase locked double rings) when the main pulse interacts with the target. These fascinating ion dynamics are mainly due to the trapping effect from the ponderomotive potential well of a formed moving standing wave (i.e. the interference between the incoming pulse and the pulse reflected by a slowly moving surface) at nodes, quite different from the standard RPA process. A theoretical model is derived to explain the underlying mechanism, and good agreements have been achieved with PIC simulations.

  16. Acute low-level alcohol consumption reduces phase locking of event-related oscillations in rodents.

    Science.gov (United States)

    Amodeo, Leslie R; Wills, Derek N; Ehlers, Cindy L

    2017-07-14

    Event-related oscillations (EROs) are rhythmic changes that are evoked by a sensory and/or cognitive stimulus that can influence the dynamics of the EEG. EROs are defined by the decomposition of the EEG signal into magnitude (energy) and phase information and can be elicited in both humans and animals. EROs have been linked to several relevant genes associated with ethanol dependence phenotypes in humans and are altered in selectively bred alcohol-preferring rats. However, pharmacological studies are only beginning to emerge investigating the impact low intoxicating doses of ethanol can have on event-related neural oscillations. The main goal of this study was to investigate the effects of low levels of voluntary consumption of ethanol, in rats, on phase locking of EROs in order to give further insight into the acute intoxicating effects of ethanol on the brain. To this end, we allow rats to self-administer unsweetened 20% ethanol over 15 intermittent sessions. This method results in a stable low-dose consumption of ethanol. Using an auditory event-related potential "oddball" paradigm, we investigated the effects of alcohol on the phase variability of EROs from electrodes implanted into the frontal cortex, dorsal hippocampus, and amygdala. We found that intermittent ethanol self-administration was sufficient to produce a significant reduction in overall intraregional synchrony across all targeted regions. These data suggest that phase locking of EROs within brain regions known to be impacted by alcohol may represent a sensitive biomarker of low levels of alcohol intoxication. Copyright © 2017 Elsevier B.V. All rights reserved.

  17. Hidden attractors in dynamical models of phase-locked loop circuits: Limitations of simulation in MATLAB and SPICE

    Science.gov (United States)

    Kuznetsov, N. V.; Leonov, G. A.; Yuldashev, M. V.; Yuldashev, R. V.

    2017-10-01

    During recent years it has been shown that hidden oscillations, whose basin of attraction does not overlap with small neighborhoods of equilibria, may significantly complicate simulation of dynamical models, lead to unreliable results and wrong conclusions, and cause serious damage in drilling systems, aircrafts control systems, electromechanical systems, and other applications. This article provides a survey of various phase-locked loop based circuits (used in satellite navigation systems, optical, and digital communication), where such difficulties take place in MATLAB and SPICE. Considered examples can be used for testing other phase-locked loop based circuits and simulation tools, and motivate the development and application of rigorous analytical methods for the global analysis of phase-locked loop based circuits.

  18. Coherent beam combination using self-phase locked stimulated Brillouin scattering phase conjugate mirrors with a rotating wedge for high power laser generation.

    Science.gov (United States)

    Park, Sangwoo; Cha, Seongwoo; Oh, Jungsuk; Lee, Hwihyeong; Ahn, Heekyung; Churn, Kil Sung; Kong, Hong Jin

    2016-04-18

    The self-phase locking of a stimulated Brillouin scattering-phase conjugate mirror (SBS-PCM) allows a simple and scalable coherent beam combination of existing lasers. We propose a simple optical system composed of a rotating wedge and a concave mirror to overcome the power limit of the SBS-PCM. Its phase locking ability and the usefulness on the beam-combination laser are demonstrated experimentally. A four-beam combination is demonstrated using this SBS-PCM scheme. The relative phases between the beams were measured to be less than λ/24.7.

  19. An all digital phase locked loop for synchronization of a sinusoidal signal embedded in white Gaussian noise

    Science.gov (United States)

    Reddy, C. P.; Gupta, S. C.

    1973-01-01

    An all digital phase locked loop which tracks the phase of the incoming sinusoidal signal once per carrier cycle is proposed. The different elements and their functions and the phase lock operation are explained in detail. The nonlinear difference equations which govern the operation of the digital loop when the incoming signal is embedded in white Gaussian noise are derived, and a suitable model is specified. The performance of the digital loop is considered for the synchronization of a sinusoidal signal. For this, the noise term is suitably modelled which allows specification of the output probabilities for the two level quantizer in the loop at any given phase error. The loop filter considered increases the probability of proper phase correction. The phase error states in modulo two-pi forms a finite state Markov chain which enables the calculation of steady state probabilities, RMS phase error, transient response and mean time for cycle skipping.

  20. Theoretical Modeling and Simulation of Phase-Locked Loop (PLL for Clock Data Recovery (CDR

    Directory of Open Access Journals (Sweden)

    Zainab Mohamad Ashari

    2012-01-01

    Full Text Available Modern communication and computer systems require rapid (Gbps, efficient  and large bandwidth data transfers. Agressive scaling of digital integrated systems  allow buses and communication controller circuits to be integrated with the microprocessor on the same chip. The  Peripheral Component Interconnect Express (PCIe protocol handles all communcation between the central processing unit (CPU and hardware devices. PCIe buses require efficient clock data recovery circuits (CDR to recover clock signals embedded in data during transmission. This paper describes the theoretical modeling and simulation of a phase-locked loop (PLL used in a CDR circuit. A simple PLL architecture for a 5 GHz CDR circuit is proposed  and elaborated in this work. Simulations were carried out using a Hardware Description Language, Verilog-AMS. The effect of jitter on the proposed design is also simulated and evaluated in this work. It was found that the proposed design is robust against both input and VCO jitter.ABSTRAK: Sistem komunikasi dan komputer moden memerlukan pemindahan data yang cekap (Gbps, dan bandwidth yang besar. Pengecilan agresif menggunakan teknik sistem digital bersepadu membenarkan bas dan litar pengawal komunikasi disatukan dengan  mikroprocessor dalam cip yang sama. Protokol persisian komponen sambung tara ekspres (PCIe mengendalikan semua komunikasi antara unit pemprosesan pusat (CPU dan peranti perkakasan. Bas PCIe memerlukan litar jam pemulihan data (CDR yang cekap untuk mendapatkan kembali isyarat jam yang tertanam dalam data semasa transmisi. Karya ini menerangkan teori pemodelan dan simulasi gelung fasa terkunci (PLL untuk CDR. Rekabentuk 5 GHz PLL yang mudah telah dicadangkan dalm kertas kerja ini. Simulasi telah dijalankan menggunakan perisian verilog-AMS. Simulasi mengunnakan kesan ketar dalam reka bentuk yang dicadangkan telah dinilai. Reka bentuk yang dicadangkan terbukti teguh mengatasi ganguan ketar di input dan VCO.KEY WORDS

  1. An injection-locked OEO based frequency doubler independent of electrical doubler phase noise deteriorating rule

    Science.gov (United States)

    Xie, Zhengyang; Zheng, Xiaoping; Li, Shangyuan; Yan, Haozhe; Xiao, Xuedi; Xue, Xiaoxiao

    2018-06-01

    We propose an injection-locked optoelectronic oscillator (OEO) based wide-band frequency doubler, which is free from phase noise deterioration in electrical doubler, by using a dual-parallel Mach-Zehnder modulator (DPMZM). Through adjusting the optical phase shifts in different arms of the DPMZM, the doubling signal oscillates in the OEO loop while the fundamental signal takes on phase modulation over the light and vanishes at photo-detector (PD) output. By controlling power of fundamental signal the restriction of phase-noise deterioration rule in electrical doubler is totally canceled. Experimental results show that the doubler output has a better phase noise value of, for example, -117 dBc/Hz @ 10 kHz at 6 GHz with an improvement more than 17 dB and 23 dB compared with that of fundamental input and electrical doubler, respectively. Besides, the stability of this doubler output can reach to 1 . 5 × 10-14 at 1000 s averaging time. The frequency range of doubling signal is limited by the bandwidth of electrical amplifier in OEO loop.

  2. Study of GNSS Loss of Lock Characteristics under Ionosphere Scintillation with GNSS Data at Weipa (Australia) During Solar Maximum Phase.

    Science.gov (United States)

    Liu, Yang; Fu, Lianjie; Wang, Jinling; Zhang, Chunxi

    2017-09-25

    One of the adverse impacts of scintillation on GNSS signals is the loss of lock status, which can lead to GNSS geometry and visibility reductions that compromise the accuracy and integrity of navigation performance. In this paper the loss of lock based on ionosphere scintillation in this solar maximum phase has been well investigated with respect to both temporal and spatial behaviors, based on GNSS observatory data collected at Weipa (Australia; geographic: 12.45° S, 130.95° E; geomagnetic: 21.79° S, 214.41° E) from 2011 to 2015. Experiments demonstrate that the percentage of occurrence of loss of lock events under ionosphere scintillation is closely related with solar activity and seasonal shifts. Loss of lock behaviors under ionosphere scintillation related to elevation and azimuth angles are statistically analyzed, with some distinct characteristics found. The influences of daytime scintillation and geomagnetic storms on loss of lock have also been discussed in details. The proposed work is valuable for a deeper understanding of theoretical mechanisms of-loss of lock under ionosphere scintillation in global regions, and provides a reference for GNSS applications in certain regions at Australian low latitudes.

  3. Role of phase matching in pulsed second-harmonic generation: Walk-off and phase-locked twin pulses in negative-index media

    International Nuclear Information System (INIS)

    Roppo, Vito; Centini, Marco; Sibilia, Concita; Bertolotti, Mario; De Ceglia, Domenico; Scalora, Michael; Akozbek, Neset; Bloemer, Mark J.; Haus, Joseph W.; Kosareva, Olga G.; Kandidov, Valery P.

    2007-01-01

    The present investigation is concerned with the study of pulsed second-harmonic generation under conditions of phase and group velocity mismatch, and generally low conversion efficiencies and pump intensities. In positive-index, nonmetallic materials, we generally find qualitative agreement with previous reports regarding the presence of a double-peaked second harmonic signal, which comprises a pulse that walks off and propagates at the nominal group velocity one expects at the second-harmonic frequency, and a second pulse that is 'captured' and propagates under the pump pulse. We find that the origin of the double-peaked structure resides in a phase-locking mechanism that characterizes not only second-harmonic generation, but also χ (3) processes and third-harmonic generation. The phase-locking mechanism that we describe occurs for arbitrarily small pump intensities, and so it is not a soliton effect, which usually relies on a threshold mechanism, although multicolor solitons display similar phase locking characteristics. Thus, in second harmonic generation a phase-matched component is always generated, even under conditions of material phase mismatch: This component is anomalous, because the material does not allow energy exchange between the pump and the second-harmonic beam. On the other hand, if the material is phase matched, phase locking and phase matching are indistinguishable, and the conversion process becomes efficient. We also report a similar phase-locking phenomenon in negative index materials. A spectral analysis of the pump and the generated signals reveals that the phase-locking phenomenon causes the forward moving, phase-locked second-harmonic pulse to experience the same negative index as the pump pulse, even though the index of refraction at the second-harmonic frequency is positive. Our analysis further shows that the reflected second-harmonic pulse generated at the interface and the forward-moving, phase-locked pulse appear to be part of the

  4. Efficient phase locking of two dual-wavelength fiber amplifiers by an all-optical self-feedback loop

    Science.gov (United States)

    Lei, Bing; Chen, Keshan; Yao, Tianfu; Shi, Jianhua; Hu, Haojun

    2017-10-01

    Efficient phase locking of two dual-wavelength fiber amplifiers has been demonstrated by using a self-feedback coupling and intracavity filtering configuration, and the effect of bandwidth and wavelength spacing on their phase locking performances have been investigated in experiment. Two independent fiber lasers with different operating wavelength were combined incoherently by a 3 dB fiber coupler to form a dual-wavelength seed source laser, which was injected into the fiber amplifiers' coupling array through the self-feedback loop. The effect of bandwidth and wavelength spacing was researched by altering the seed laser's pump power and operating wavelengths respectively. As long as the feedback loop and the single-mode fiber filtering configuration were well constructed in the unidirectional ring laser cavity, stable phase locking states and high fringe visibility interference patterns could always be obtained in our experiment. When the spacing of two operating wavelength was varied from 1.6 nm to 19.6 nm, the fringe visibility decreased slightly with the increase of wavelength spacing, and the corresponding fringe visibility was always larger than 0.6. In conclusion, we believe that efficient phase locking of several multi-wavelength laser sources is also feasible by passive self-adjusting methods, and keeping the component laser beams' phase relationship stable and fixed is more important than controlling their operating wavelengths.

  5. Development of scalable frequency and power Phase-Locked Loop in 130nm CMOS technology

    CERN Document Server

    Firlej, M; Idzik, M; Moron, J; Swientek, K

    2014-01-01

    The design and measurements results of a prototype very low power Phase-Locked Loop (PLL) ASIC for applications in readout systems of particle physics detectors are presented. The PLL was fabricated in 130 nm CMOS technology. It was designed and simulated for frequency range 10 MHz–3.5 GHz. Four division factors i.e. 6, 8, 10 and 16 were implemented in the PLL feedback loop. The main PLL block-voltage controlled oscillator (VCO) should work in 16 frequency ranges/modes, switched either manually or automatically. Preliminary measurements done in frequency range 20 MHz–1.6 GHz showed that the ASIC is functional and generates proper clock signal. The automatic VCO mode switching, one of the main design goals, was positively verified. Power consumption of around 0.6mW was measured at 1 GHz for a division factor equal to 10.

  6. Development of scalable frequency and power Phase-Locked Loop in 130 nm CMOS technology

    International Nuclear Information System (INIS)

    Firlej, M; Fiutowski, T; Idzik, M; Moroń, J; Świentek, K

    2014-01-01

    The design and measurements results of a prototype very low power Phase-Locked Loop (PLL) ASIC for applications in readout systems of particle physics detectors are presented. The PLL was fabricated in 130 nm CMOS technology. It was designed and simulated for frequency range 10 MHz–3.5 GHz. Four division factors i.e. 6, 8, 10 and 16 were implemented in the PLL feedback loop. The main PLL block-voltage controlled oscillator (VCO) should work in 16 frequency ranges/modes, switched either manually or automatically. Preliminary measurements done in frequency range 20 MHz–1.6 GHz showed that the ASIC is functional and generates proper clock signal. The automatic VCO mode switching, one of the main design goals, was positively verified. Power consumption of around 0.6 mW was measured at 1 GHz for a division factor equal to 10

  7. Oscillatory solitons and time-resolved phase locking of two polariton condensates

    International Nuclear Information System (INIS)

    Christmann, Gabriel; Tosi, Guilherme; Baumberg, Jeremy J; Berloff, Natalia G; Tsotsis, Panagiotis; Eldridge, Peter S; Hatzopoulos, Zacharias; Savvidis, Pavlos G

    2014-01-01

    When pumped nonresonantly, semiconductor microcavity polaritons form Bose–Einstein condensates that can be manipulated optically. Using tightly-focused excitation spots, radially expanding condensates can be formed in close proximity. Using high time resolution streak camera measurements we study the time dependent properties of these macroscopic coherent states. By coupling this method with interferometry we observe directly the phase locking of two independent condensates in time, showing the effect of polariton–polariton interactions. We also directly observe fast spontaneous soliton-like oscillations of the polariton cloud trapped between the pump spots, which can be either dark or bright solitons. This transition from dark to bright is a consequence of the change of sign of the nonlinearity which we propose is due to the shape of the polariton dispersion leading to either positive or negative polariton effective mass. (paper)

  8. Efficient coherent beam combination of two-dimensional phase-locked laser arrays

    International Nuclear Information System (INIS)

    Li, Bing; Yan, Aimin; Liu, Liren; Dai, Enwen; Sun, Jianfeng; Shen, Baoliang; Lv, Xiaoyu; Wu, Yapeng

    2011-01-01

    An efficient technique in which a two-dimensional (2D) phase-locked laser array can be coherently combined into a high power and high quality beam by using a conjugate Dammann grating (CDG) is presented. A theoretical model is established to provide a physical interpretation of the proposed scheme. Using this technique, we investigate analytically and numerically the coherent combination of 2D laser arrays such as 5 × 5 and 32 × 32 arrangements. Far-field distributions and the near-field pattern of the combined beam are calculated and compared with experimental results. A verification experiment with a simulated 5 × 5 2D laser array using an aperture mask has been performed. Calculations and experimental results show that the proposed technique in this paper is an efficient coherent beam combination method to obtain a high power and high quality beam from laser arrays

  9. Propagation of a radial phased-locked Lorentz beam array in turbulent atmosphere.

    Science.gov (United States)

    Zhou, Guoquan

    2011-11-21

    A radial phased-locked (PL) Lorentz beam array provides an appropriate theoretical model to describe a coherent diode laser array, which is an efficient radiation source for high-power beaming use. The propagation of a radial PL Lorentz beam array in turbulent atmosphere is investigated. Based on the extended Huygens-Fresnel integral and some mathematical techniques, analytical formulae for the average intensity and the effective beam size of a radial PL Lorentz beam array are derived in turbulent atmosphere. The average intensity distribution and the spreading properties of a radial PL Lorentz beam array in turbulent atmosphere are numerically calculated. The influences of the beam parameters and the structure constant of the atmospheric turbulence on the propagation of a radial PL Lorentz beam array in turbulent atmosphere are discussed in detail. © 2011 Optical Society of America

  10. Vortex spin-torque oscillator stabilized by phase locked loop using integrated circuits

    Directory of Open Access Journals (Sweden)

    Martin Kreissig

    2017-05-01

    Full Text Available Spin-torque nano-oscillators (STO are candidates for the next technological implementation of spintronic devices in commercial electronic systems. For use in microwave applications, improving the noise figures by efficient control of their phase dynamics is a mandatory requirement. In order to achieve this, we developed a compact phase locked loop (PLL based on custom integrated circuits (ICs and demonstrate that it represents an efficient way to reduce the phase noise level of a vortex based STO. The advantage of our approach to phase stabilize STOs is that our compact system is highly reconfigurable e.g. in terms of the frequency divider ratio N, RF gain and loop gain. This makes it robust against device to device variations and at the same time compatible with a large range of STOs. Moreover, by taking advantage of the natural highly non-isochronous nature of the STO, the STO frequency can be easily controlled by e.g. changing the divider ratio N.

  11. Novel automatic phase lock determination for superconducting cavity tests at vertical test stand at RRCAT

    International Nuclear Information System (INIS)

    Singh, Kunver Adarsh Pratap; Mohania, Praveen; Rajput, Vikas; Baxy, Deodatta; Shrivastava, Purushottam

    2015-01-01

    RRCAT has developed a Vertical Test Stand (VTS) which is used to test the Nb superconducting cavities under cryogenic conditions. In the VTS, RF cavity is characterized for its quality factor variation vs the accelerating gradient. The RF system is an essential part of the VTS which is required to provide stable RF power to the cavity in terms of amplitude, frequency and phase. RF system of VTS consists of several modules including the LLRF system. The LLRF system consists of the 'Frequency Control Module' which controls the input frequency to the SCRF cavity. Due to high quality factor, bandwidth of the cavity is less than 1 Hz. Even slight mechanical vibrations (microphonics) causes change in cavity resonance frequency resulting in total reflection of incident power. A PLL based frequency tracking module has been used to track the resonant frequency of RF cavity. This module changes RF source frequency according to change in Cavity resonance frequency. A novel method using a LabView based computer program has been developed which changes the phase of input RF signal using IQ modulator and monitors the transmitted power, incident and reflected power. The program plots the graph between phase and ratio of transmitted power to incident/reflected power and gives optimum locking phase for operation which has resulted in significant saving in the overall process time for the tests of the cavities in VTS. (author)

  12. An Adaptive Tuning Mechanism for Phase-Locked Loop Algorithms for Faster Time Performance of Interconnected Renewable Energy Sources

    DEFF Research Database (Denmark)

    Hadjidemetriou, Lenos; Kyriakides, Elias; Blaabjerg, Frede

    2015-01-01

    Interconnected renewable energy sources (RES) require fast and accurate fault ride through (FRT) operation, in order to support the power grid, when faults occur. This paper proposes an adaptive phase-locked loop (adaptive dαβPLL) algorithm, which can be used for a faster and more accurate response...

  13. An improved synchronous reference frame phase-locked loop for stand-alone variable speed constant frequency power generation systems

    DEFF Research Database (Denmark)

    Liu, Yi; Xu, Wei; Ke, Longzhang

    2017-01-01

    The phase-locked loop (PLL) based on conventional synchronous reference frame, i.e. dqPLL, is usually employed in grid-connected variable speed constant frequency (VSCF) power generation systems (PGSs). However, the voltage amplitude drop of stand-alone PGSs is often greater than that of the grid...

  14. Phase locking of 2.324 and 2.959 terahertz quantum cascade lasers using a Schottky diode harmonic mixer.

    Science.gov (United States)

    Danylov, Andriy; Erickson, Neal; Light, Alexander; Waldman, Jerry

    2015-11-01

    The 23rd and 31st harmonics of a microwave signal generated in a novel THz balanced Schottky diode mixer were used as a frequency stable reference source to phase lock solid-nitrogen-cooled 2.324 and 2.959 THz quantum cascade lasers. Hertz-level frequency stability was achieved, which was maintained for several hours.

  15. An Adaptive Least-Error Squares Filter-Based Phase-Locked Loop for Synchronization and Signal Decomposition Purposes

    DEFF Research Database (Denmark)

    Golestan, Saeed; Ebrahimzadeh, Esmaeil; Guerrero, Josep M.

    2017-01-01

    Without any doubt, phase-locked loops (PLLs) are the most popular and widely used technique for the synchronization purposes in the power and energy areas. They are also popular for the selective extraction of fundamental and harmonic/disturbance components of the grid voltage and current. Like m...

  16. Analysis of the effects of time delay in clock recovery circuits based on Phase-locked loops

    DEFF Research Database (Denmark)

    Zibar, Darko; Oxenløwe, Leif Katsuo; Clausen, Anders

    2004-01-01

    Influence of time delay in a balanced optical phase-locked loops (OPLL) with a proportional integrator (Pl) filter is investigated using a delayed differential equation (DDE) is investigated. The limitations, which a time delay imposes on the Pl filter bandwidth, at increasing values of loop gain...

  17. 3D pressure imaging of an aircraft propeller blade-tip flow by phase-locked stereoscopic PIV

    NARCIS (Netherlands)

    Ragni, D.; Van Oudheusden, B.W.; Scarano, F.

    2011-01-01

    The flow field at the tip region of a scaled DHC Beaver aircraft propeller, running at transonic speed, has been investigated by means of a multi-plane stereoscopic particle image velocimetry setup. Velocity fields, phase-locked with the blade rotational motion, are acquired across several planes

  18. Identifying seizure onset zone from electrocorticographic recordings: A machine learning approach based on phase locking value.

    Science.gov (United States)

    Elahian, Bahareh; Yeasin, Mohammed; Mudigoudar, Basanagoud; Wheless, James W; Babajani-Feremi, Abbas

    2017-10-01

    Using a novel technique based on phase locking value (PLV), we investigated the potential for features extracted from electrocorticographic (ECoG) recordings to serve as biomarkers to identify the seizure onset zone (SOZ). We computed the PLV between the phase of the amplitude of high gamma activity (80-150Hz) and the phase of lower frequency rhythms (4-30Hz) from ECoG recordings obtained from 10 patients with epilepsy (21 seizures). We extracted five features from the PLV and used a machine learning approach based on logistic regression to build a model that classifies electrodes as SOZ or non-SOZ. More than 96% of electrodes identified as the SOZ by our algorithm were within the resected area in six seizure-free patients. In four non-seizure-free patients, more than 31% of the identified SOZ electrodes by our algorithm were outside the resected area. In addition, we observed that the seizure outcome in non-seizure-free patients correlated with the number of non-resected SOZ electrodes identified by our algorithm. This machine learning approach, based on features extracted from the PLV, effectively identified electrodes within the SOZ. The approach has the potential to assist clinicians in surgical decision-making when pre-surgical intracranial recordings are utilized. Copyright © 2017 British Epilepsy Association. Published by Elsevier Ltd. All rights reserved.

  19. FPGA Implementation of an Amplitude-Modulated Continuous-Wave Ultrasonic Ranger Using Restructured Phase-Locking Scheme

    Directory of Open Access Journals (Sweden)

    P. Sumathi

    2010-01-01

    Full Text Available An accurate ultrasonic range finder employing Sliding Discrete Fourier Transform (SDFT based restructured phase-locked loop (RPLL, which is an improved version of the recently proposed integrated phase-locking scheme (IPLL, has been expounded. This range finder principally utilizes amplitude-modulated ultrasonic waves assisted by an infrared (IR pilot signal. The phase shift between the envelope of the reference IR pilot signal and that of the received ultrasonic signal is proportional to the range. The extracted envelopes are filtered by SDFT without introducing any additional phase shift. A new RPLL is described in which the phase error is driven to zero using the quadrature signal derived from the SDFT. Further, the quadrature signal is reinforced by another cosine signal derived from a lookup table (LUT. The pulse frequency of the numerically controlled oscillator (NCO is extremely accurate, enabling fine tuning of the SDFT and RPLL also improves the lock time for the 50 Hz input signal to 0.04 s. The percentage phase error for the range 0.6 m to 6 m is about 0.2%. The VHDL codes generated for the various signal processing steps were downloaded into a Cyclone FPGA chip around which the ultrasonic ranger had been built.

  20. Spatiotemporal dynamics of a digital phase-locked loop based coupled map lattice system

    Energy Technology Data Exchange (ETDEWEB)

    Banerjee, Tanmoy, E-mail: tbanerjee@phys.buruniv.ac.in; Paul, Bishwajit; Sarkar, B. C. [Department of Physics, University of Burdwan, Burdwan, West Bengal 713 104 (India)

    2014-03-15

    We explore the spatiotemporal dynamics of a coupled map lattice (CML) system, which is realized with a one dimensional array of locally coupled digital phase-locked loops (DPLLs). DPLL is a nonlinear feedback-controlled system widely used as an important building block of electronic communication systems. We derive the phase-error equation of the spatially extended system of coupled DPLLs, which resembles a form of the equation of a CML system. We carry out stability analysis for the synchronized homogeneous solutions using the circulant matrix formalism. It is shown through extensive numerical simulations that with the variation of nonlinearity parameter and coupling strength the system shows transitions among several generic features of spatiotemporal dynamics, viz., synchronized fixed point solution, frozen random pattern, pattern selection, spatiotemporal intermittency, and fully developed spatiotemporal chaos. We quantify the spatiotemporal dynamics using quantitative measures like average quadratic deviation and spatial correlation function. We emphasize that instead of using an idealized model of CML, which is usually employed to observe the spatiotemporal behaviors, we consider a real world physical system and establish the existence of spatiotemporal chaos and other patterns in this system. We also discuss the importance of the present study in engineering application like removal of clock-skew in parallel processors.

  1. Hybrid phase-locked loop with fast locking time and low spur in a 0.18-μm CMOS process

    International Nuclear Information System (INIS)

    Zhu Si-Heng; Si Li-Ming; Guo Chao; Shi Jun-Yu; Zhu Wei-Ren

    2014-01-01

    We propose a novel hybrid phase-locked loop (PLL) architecture for overcoming the trade-off between fast locking time and low spur. To reduce the settling time and meanwhile suppress the reference spurs, we employ a wide-band single-path PLL and a narrow-band dual-path PLL in a transient state and a steady state, respectively, by changing the loop bandwidth according to the gain of voltage controlled oscillator (VCO) and the resister of the loop filter. The hybrid PLL is implemented in a 0.18-μm complementary metal oxide semiconductor (CMOS) process with a total die area of 1.4×0.46 mm 2 . The measured results exhibit a reference spur level of lower than −73 dB with a reference frequency of 10 MHz and a settling time of 20 μs with 40 MHz frequency jump at 2 GHz. The total power consumption of the hybrid PLL is less than 27 mW with a supply voltage of 1.8 V. (interdisciplinary physics and related areas of science and technology)

  2. Hybrid phase-locked loop with fast locking time and low spur in a 0.18-μm CMOS process

    Science.gov (United States)

    Zhu, Si-Heng; Si, Li-Ming; Guo, Chao; Shi, Jun-Yu; Zhu, Wei-Ren

    2014-07-01

    We propose a novel hybrid phase-locked loop (PLL) architecture for overcoming the trade-off between fast locking time and low spur. To reduce the settling time and meanwhile suppress the reference spurs, we employ a wide-band single-path PLL and a narrow-band dual-path PLL in a transient state and a steady state, respectively, by changing the loop bandwidth according to the gain of voltage controlled oscillator (VCO) and the resister of the loop filter. The hybrid PLL is implemented in a 0.18-μm complementary metal oxide semiconductor (CMOS) process with a total die area of 1.4×0.46 mm2. The measured results exhibit a reference spur level of lower than -73 dB with a reference frequency of 10 MHz and a settling time of 20 μs with 40 MHz frequency jump at 2 GHz. The total power consumption of the hybrid PLL is less than 27 mW with a supply voltage of 1.8 V.

  3. Color superconductivity: Phase diagrams and Goldstone bosons in the color-flavor locked phase

    International Nuclear Information System (INIS)

    Kleinhaus, Verena

    2009-01-01

    The phase diagram of strongly interacting matter is studied with great experimental and theoretical effort and is one of the most fascinating research areas in modern particle physics. It is believed that color superconducting phases, in which quarks form Cooper pairs, appear at very high densities and low temperatures. Such phases could appear in the cores of neutron stars. In this work color superconducting phases are studied within the Nambu-Jona-Lasinio model. First of all, the phase diagram of neutral matter in beta equilibrium is calculated for two different diquark couplings. To this end, we determine the dynamical quark masses self-consistently together with the order parameters of color superconductivity. The interplay between neutrality and quark masses results in an interesting phase structure, in particular for the smaller diquark coupling. In the following, we additionally include a conserved lepton number to map the situation in the first few seconds of the evolution of a protoneutron star when neutrinos are trapped. This has a huge influence on the phase structure and favors the 2SC phase compared to the CFL phase. In the second part of this work we concentrate on the CFL phase which is characterized by a special symmetry breaking pattern. The properties of the resulting nine pseudoscalar Goldstone bosons (GB) are studied by solving the Bethe-Salpeter equation for quark-quark scattering. The GB are the lowest-lying excitations in the CFL phase and therefore play an important role for the thermodynamics of the system. The properties of the GB can also be described by the low-energy effective theory (LEET) for the CFL phase. There the respective low-energy constants are derived for asymptotically high densities where the strong force is weak and can be treated perturbatively. Our aim is the comparison of our results with these predictions, on the one hand to check our model in the weak-coupling limit and on the other hand to derive information about

  4. Color superconductivity. Phase diagrams and Goldstone bosons in the color-flavor locked phase

    Energy Technology Data Exchange (ETDEWEB)

    Kleinhaus, Verena

    2009-04-29

    The phase diagram of strongly interacting matter is studied with great experimental and theoretical effort and is one of the most fascinating research areas in modern particle physics. It is believed that color superconducting phases, in which quarks form Cooper pairs, appear at very high densities and low temperatures. Such phases could appear in the cores of neutron stars. In this work color superconducting phases are studied within the Nambu-Jona-Lasinio model. First of all, the phase diagram of neutral matter in beta equilibrium is calculated for two different diquark couplings. To this end, we determine the dynamical quark masses self-consistently together with the order parameters of color superconductivity. The interplay between neutrality and quark masses results in an interesting phase structure, in particular for the smaller diquark coupling. In the following, we additionally include a conserved lepton number to map the situation in the first few seconds of the evolution of a protoneutron star when neutrinos are trapped. This has a huge influence on the phase structure and favors the 2SC phase compared to the CFL phase. In the second part of this work we concentrate on the CFL phase which is characterized by a special symmetry breaking pattern. The properties of the resulting nine pseudoscalar Goldstone bosons (GB) are studied by solving the Bethe-Salpeter equation for quark-quark scattering. The GB are the lowest-lying excitations in the CFL phase and therefore play an important role for the thermodynamics of the system. The properties of the GB can also be described by the low-energy effective theory (LEET) for the CFL phase. There the respective low-energy constants are derived for asymptotically high densities where the strong force is weak and can be treated perturbatively. Our aim is the comparison of our results with these predictions, on the one hand to check our model in the weak-coupling limit and on the other hand to derive information about

  5. Alpha-Band Rhythms in Visual Task Performance: Phase-Locking by Rhythmic Sensory Stimulation

    Science.gov (United States)

    de Graaf, Tom A.; Gross, Joachim; Paterson, Gavin; Rusch, Tessa; Sack, Alexander T.; Thut, Gregor

    2013-01-01

    Oscillations are an important aspect of neuronal activity. Interestingly, oscillatory patterns are also observed in behaviour, such as in visual performance measures after the presentation of a brief sensory event in the visual or another modality. These oscillations in visual performance cycle at the typical frequencies of brain rhythms, suggesting that perception may be closely linked to brain oscillations. We here investigated this link for a prominent rhythm of the visual system (the alpha-rhythm, 8–12 Hz) by applying rhythmic visual stimulation at alpha-frequency (10.6 Hz), known to lead to a resonance response in visual areas, and testing its effects on subsequent visual target discrimination. Our data show that rhythmic visual stimulation at 10.6 Hz: 1) has specific behavioral consequences, relative to stimulation at control frequencies (3.9 Hz, 7.1 Hz, 14.2 Hz), and 2) leads to alpha-band oscillations in visual performance measures, that 3) correlate in precise frequency across individuals with resting alpha-rhythms recorded over parieto-occipital areas. The most parsimonious explanation for these three findings is entrainment (phase-locking) of ongoing perceptually relevant alpha-band brain oscillations by rhythmic sensory events. These findings are in line with occipital alpha-oscillations underlying periodicity in visual performance, and suggest that rhythmic stimulation at frequencies of intrinsic brain-rhythms can be used to reveal influences of these rhythms on task performance to study their functional roles. PMID:23555873

  6. tACS phase locking of frontal midline theta oscillations disrupts working memory performance

    Directory of Open Access Journals (Sweden)

    Bankim Subhash Chander

    2016-05-01

    Full Text Available Frontal midline theta (FMT oscillations (4-8Hz are strongly related to cognitive and executive control during mental tasks such as memory processing, arithmetic problem solving or sustained attention. While maintenance of temporal order information during a working memory (WM task was recently linked to FMT phase, a positive correlation between FMT power, WM demand and WM performance was shown. However, the relationship between these measures is not well understood, and it is unknown whether purposeful FMT phase manipulation during a WM task impacts FMT power and WM performance. Here we present evidence that FMT phase manipulation mediated by transcranial alternating current stimulation (tACS can block WM demand-related FMT power increase and disrupt normal WM performance. Methods: 20 healthy volunteers were assigned to one of two groups (group A, group B and performed a 2-back task across a baseline block (block 1 and an intervention block (block 2 while 275-sensor magnetoencephalography (MEG was recorded. After no stimulation was applied during block 1, participants in group A received tACS oscillating at their individual FMT frequency over the prefrontal cortex (PFC while group B received sham stimulation during block 2. After assessing and mapping phase locking values (PLV between the tACS signal and brain oscillatory activity across the whole brain, FMT power and WM performance were assessed and compared between blocks and groups. Results: During block 2 of group A but not B, FMT oscillations showed increased PLV across task-related cortical areas underneath the frontal tACS electrode. While WM task-related FMT power increase (FMTpower and WM performance were comparable across groups in block 1, tACS resulted in lower FMTpower and WM performance compared to sham stimulation in block 2. Conclusion: tACS-related manipulation of FMT phase can disrupt WM performance and influence WM task-related FMT power increase. This finding may have

  7. Phase-locking and chaos in a silent Hodgkin-Huxley neuron exposed to sinusoidal electric field

    International Nuclear Information System (INIS)

    Che Yanqiu; Wang Jiang; Si Wenjie; Fei Xiangyang

    2009-01-01

    Neuronal firing patterns are related to the information processing in neural system. This paper investigates the response characteristics of a silent Hodgkin-Huxley neuron to the stimulation of externally-applied sinusoidal electric field. The neuron exhibits both p:q phase-locked (i.e. a periodic oscillation defined as p action potentials generated by q cycle stimulations) and chaotic behaviors, depending on the values of stimulus frequencies and amplitudes. In one-parameter space, a rich bifurcation structure including period-adding without chaos and phase-locking alternated with chaos suggests frequency discrimination of the neuronal firing patterns. Furthermore, by mapping out Arnold tongues, we partition the amplitude-frequency parameter space in terms of the qualitative behaviors of the neuron. Thus the neuron's information (firing patterns) encodes the stimulus information (amplitude and frequency), and vice versa

  8. Long term carrier envelope phase stabilization of a grating based high power femtosecond laser using the direct locking method

    International Nuclear Information System (INIS)

    Lee, Jae Hwan; Lee, Youg Soo; Park, Juyun; Nam, Chang Hee; Yu, Tae Jun

    2008-01-01

    The carrier envelope phase (CEP)stabilization of femtosecond laser pulses has been intensively investigated for ultrafast science as well as for frequency metrology. In the case of few cycle pulses stabilization and control of the CEP is an important issue, since the electric field profile changes with CEP variation. We have developed the direct locking method to stabilize the CEP for the investigation of attosecond physics. The direct locking method uses the beating signal itself, measured using an f to 2f interferometer, as an error signal to a feedback loop. The direct locking method quenches the beating signal so that the CEP variation between successive pulses become zero and every pulses from the oscillator ts identical. Due to the direct use of the beating signal, the signal processing is simple and complex equipment, used in the case of the phase locked loop (PLL)method operating in the frequency domain, are not required. For long term stability, we have proposed and implemented a double feedback technique, and achieved CEP stabilization of the oscillator for 24 hours, as shown in Fig. 1. This long term CEP stabilization was achieved without realignment of any optical components. The CEP stabilization for a whole day is a clear demonstration of the robustness of the direct locking method. The amplification of CEP stabilized laser pulses induces additional CEP variation. Even though the CEP of an oscillator is stabilized, the CEP drift is generated again during amplification due to external perturbations, such as pumping power fluctuation and beam pointing fluctuation. To measure the CEP drift of the amplified pulses, a spectral interferometer (SI)was employed. The CEP drift obtained from SI was used as the error signal of another feedback loop installed in the amplifier chain. To compensate for the large CEP drift induced during amplification, the grating separation of the pulse compressor was adjusted. Figure 2 shows the result of CEP stabilization of

  9. Nicolau syndrome caused by the "self-injection" of diclofenac

    Directory of Open Access Journals (Sweden)

    Selcuk Yaylaci

    2016-01-01

    Full Text Available Nicolau syndrome (NS is a rare injection-related local complication. Some drugs have been implicated to cause this syndrome. Several cases were previously reported in the literature. In this paper, an interesting case of NS in a 30-year-old male patient after intramuscular self-injection of diclofenac was presented.

  10. Frequency and Phase-lock Control of a 3 THz Quantum Cascade Laser

    Science.gov (United States)

    Betz, A. L.; Boreiko, R. T.; Williams, B. S.; Kumar, S.; Hu, Q.; Reno, J. L.

    2005-01-01

    We have locked the frequency of a 3 THz quantum cascade laser (QCL) to that of a far-infrared gas laser with a tunable microwave offset frequency. The locked QCL line shape is essentially Gaussian, with linewidths of 65 and 141 kHz at the -3 and -10 dB levels, respectively. The lock condition can be maintained indefinitely, without requiring temperature or bias current regulation of the QCL other than that provided by the lock error signal. The result demonstrates that a terahertz QCL can be frequency controlled with l-part-in-lO(exp 8) accuracy, which is a factor of 100 better than that needed for a local oscillator in a heterodyne receiver for atmospheric and astronomic spectroscopy.

  11. Frequency-Locked Single-Frequency Fiber Laser at 2 Micron, Phase II

    Data.gov (United States)

    National Aeronautics and Space Administration — Frequency-locked single-frequency 2 micron fiber laser is proposed to be used for airborne/spaceborne coherent lidar measurements, i.e., Active Sensing of CO2...

  12. Saccades phase-locked to alpha oscillations in the occipital and medial temporal lobe enhance memory encoding

    OpenAIRE

    Noachtar, Soheyl; Doeller, Christian; Jensen, Ole; Hartl, Elisabeth; Staudigl, Tobias

    2017-01-01

    Efficient sampling of visual information requires a coordination of eye movements and ongoing brain oscillations. Using intracranial and MEG recordings, we show that saccades are locked to the phase of visual alpha oscillations, and that this coordination supports mnemonic encoding of visual scenes. Furthermore, parahippocampal and retrosplenial cortex involvement in this coordination reflects effective vision-to-memory mapping, highlighting the importance of neural oscillations for the inter...

  13. First demonstration and performance of an injection locked continuous wave magnetron to phase control a superconducting cavity

    Directory of Open Access Journals (Sweden)

    A. C. Dexter

    2011-03-01

    Full Text Available The applications of magnetrons to high power proton and cw electron linacs are discussed. An experiment is described where a 2.45 GHz magnetron has been used to drive a single cell superconducting cavity. With the magnetron injection locked, a modest phase control accuracy of 0.95° rms has been demonstrated. Factors limiting performance have been identified.

  14. Study on Soft Phase Locked Method to Solving the Synchronization Problem of Active Power Filter in Stand-alone Power Grid

    DEFF Research Database (Denmark)

    Zhuo, Fang; Wu, Longhui; Chen, Zhe

    2009-01-01

    on zero-cross detection can't work effectively in small rating stand-alone power grid. Then a soft phase locked loop with additional filter is proposed. It can lock the phase angle on to the positive sequence of fundamental voltage accurately and rapidly. It ensures the performance of APF applied...... in the small rating stand-alone power grid. Moreover, the soft phase locked loop is easy to be implemented in a Digital Signal Processor (DSP). Simulation and experimental results validate that the soft phase locked loop has satisfactory performance.......Traditional LC filters can't work stably in small rating stand-alone power grid. So active power filter (APF) is becoming an important tool to solve the power quality problem in small rating stand-alone power grid. In most current detection algorithm of APF, it needs a synchronizing signal. Firstly...

  15. 3D nonlinear modeling of the coupling and phase locking of magnetic Islands in tokamaks

    Science.gov (United States)

    Jardin, Stephen; Ferraro, Nathaniel; Chen, Jin; Pfefferle, David

    2017-10-01

    Many tokamak discharges develop multiple tearing modes possessing different mode numbers. These modes are observed to phase lock to one another, resulting in a flattening of the core toroidal plasma rotation profile, which can have deleterious effects on transport and MHD stability. In order to study these phenomena with minimum assumptions, we use the M3D-C1 3D nonlinear MHD code to perform initial value simulations of the evolution of equilibria unstable to both the 2/1 and 3/2 modes, but having sheared toroidal rotation. Initial attempts to perform these simulations led to numerical instabilities developing once the islands got to a certain size. In order to study the cause of this instability, we developed a small model code that solves a pure convection equation in 1D. We find that an implicit Crank-Nicholson method in time and Hermite Cubic finite elements (as are used in the toroidal direction in the M3D-C1 code) is not a convergent algorithm. Adding a small second order diffusion term, proportional to the velocity, improves the numerical stability properties but is not convergent in the first-derivative of the solution. Instead, adding a much smaller forth-order spatial derivative term proportional to the velocity leads to an algorithm in which both the solution and the first derivative converge as 1/N2,. Adding similar toroidal forth derivative terms to the M3D-C1 code eliminated the numerical instability. This work was supported by US DOE Contract DE-AC02-09-CH11466.

  16. Phase-locking of a 2.5 THz quantum cascade laser to a frequency comb using a GaAs photomixer.

    Science.gov (United States)

    Ravaro, M; Manquest, C; Sirtori, C; Barbieri, S; Santarelli, G; Blary, K; Lampin, J-F; Khanna, S P; Linfield, E H

    2011-10-15

    We report the heterodyne detection and phase locking of a 2.5 THz quantum cascade laser (QCL) using a terahertz frequency comb generated in a GaAs photomixer using a femtosecond fiber laser. With 10 mW emitted by the QCL, the phase-locked signal at the intermediate frequency yields 80 dB of signal-to-noise ratio in a bandwidth of 1 Hz.

  17. Forced phase-locked states and information retrieval in a two-layer network of oscillatory neurons with directional connectivity

    International Nuclear Information System (INIS)

    Kazantsev, Victor; Pimashkin, Alexey

    2007-01-01

    We propose two-layer architecture of associative memory oscillatory network with directional interlayer connectivity. The network is capable to store information in the form of phase-locked (in-phase and antiphase) oscillatory patterns. The first (input) layer takes an input pattern to be recognized and their units are unidirectionally connected with all units of the second (control) layer. The connection strengths are weighted using the Hebbian rule. The output (retrieved) patterns appear as forced-phase locked states of the control layer. The conditions are found and analytically expressed for pattern retrieval in response on incoming stimulus. It is shown that the system is capable to recover patterns with a certain level of distortions or noises in their profiles. The architecture is implemented with the Kuramoto phase model and using synaptically coupled neural oscillators with spikes. It is found that the spiking model is capable to retrieve patterns using the spiking phase that translates memorized patterns into the spiking phase shifts at different time scales

  18. Generation of five phase-locked harmonics by implementing a divide-by-three optical frequency divider.

    Science.gov (United States)

    Suhaimi, Nurul Sheeda; Ohae, Chiaki; Gavara, Trivikramarao; Nakagawa, Ken'ichi; Hong, Feng-Lei; Katsuragawa, Masayuki

    2015-12-15

    We report the generation of five phase-locked harmonics, f₁:2403  nm, f₂:1201  nm, f₃:801  nm, f₄:600  nm, and f₅:480  nm with an exact frequency ratio of 1:2:3:4:5 by implementing a divide-by-three optical frequency divider in the high harmonic generation process. All five harmonics are generated coaxially with high phase coherence in time and space, which are applicable for various practical uses.

  19. A case of suicide by self-injection of adrenaline.

    Science.gov (United States)

    Palmiere, Cristian; Bévalot, Fabien; Malicier, Daniel; Grouzmann, Eric; Fracasso, Tony; Fanton, Laurent

    2015-09-01

    Adrenaline (epinephrine) auto-injectors provide life-saving pre-hospital treatment for individuals experiencing anaphylaxis in a community setting. Errors in handling adrenaline auto-injectors, particularly by children and healthcare professionals, have been reported. Reports of adrenaline overdoses are limited in the medical literature. In most of these cases, accidental adrenaline administration results from medical error. Exogenous administration of catecholamine is responsible for cardiovascular and metabolic responses, which may cause supraventricular tachycardia, ventricular dysrhythmias and myocardial ischemia. The authors present a unique autopsy case involving a 34 year-old woman who intentionally self-injected adrenaline using an adrenaline auto-injector as part of a suicide plan. Catecholamines and metanephrines were measured in peripheral and cardiac blood as well as urine and vitreous humor. Based on the results of all postmortem investigations, the cause of death was determined to be cardiac dysrhythmia and cardiac arrest following adrenaline self-injection.

  20. A low-power 802.11 AD compatible 60-GHz phase-locked loop in 65-NM CMOS

    KAUST Repository

    Cheema, Hammad M.; Arsalan, Muhammad; Salama, Khaled N.; Shamim, Atif

    2015-01-01

    A 60-GHz fundamental frequency phase locked loop (PLL) as part of a highly integrated system-on-chip transmitter with onchip memory and antenna is presented. As a result of localized optimization approach for each component, the PLL core components only consume 30.2 mW from a 1.2 V supply. A systematic design procedure to achieve high phase margin and wide locking range is presented. The reduction of parasitic and fixed capacitance contributions in the voltage controlled oscillator enables the coverage of the complete 802.11 ad frequency band from 57.2 to 65.8 GHz. A new 4-stage distribution network supplying the local oscillator (LO) signal to the mixer, the feedback loop and the external equipment is introduced. The prescaler based on the static frequency division approach is enhanced using shunt-peaking and asymmetric capacitive loading. The current mode logic based divider chain is optimized for low power and minimum silicon foot-print. A dead-zone free phase frequency detector, low leakage charge pump, and an integrated second-order passive filter completes the feedback loop. The PLL implemented in 65 nm CMOS process occupies only 0.6 mm2 of chip space and has a measured locking range from 56.8 to 66.5 GHz. The reference spurs are lower than -40 dBc and the in-band and out-of-band phase noise is -88.12 dBc/Hz and -117 dBc/Hz, respectively.

  1. A low-power 802.11 AD compatible 60-GHz phase-locked loop in 65-NM CMOS

    KAUST Repository

    Cheema, Hammad M.

    2015-01-23

    A 60-GHz fundamental frequency phase locked loop (PLL) as part of a highly integrated system-on-chip transmitter with onchip memory and antenna is presented. As a result of localized optimization approach for each component, the PLL core components only consume 30.2 mW from a 1.2 V supply. A systematic design procedure to achieve high phase margin and wide locking range is presented. The reduction of parasitic and fixed capacitance contributions in the voltage controlled oscillator enables the coverage of the complete 802.11 ad frequency band from 57.2 to 65.8 GHz. A new 4-stage distribution network supplying the local oscillator (LO) signal to the mixer, the feedback loop and the external equipment is introduced. The prescaler based on the static frequency division approach is enhanced using shunt-peaking and asymmetric capacitive loading. The current mode logic based divider chain is optimized for low power and minimum silicon foot-print. A dead-zone free phase frequency detector, low leakage charge pump, and an integrated second-order passive filter completes the feedback loop. The PLL implemented in 65 nm CMOS process occupies only 0.6 mm2 of chip space and has a measured locking range from 56.8 to 66.5 GHz. The reference spurs are lower than -40 dBc and the in-band and out-of-band phase noise is -88.12 dBc/Hz and -117 dBc/Hz, respectively.

  2. Stimulated Brillouin scattering phase-locking using a transient acoustic standing wave excited through an optical interference field

    International Nuclear Information System (INIS)

    Ondrej Slezak; Milan Kalal; Hon Jin Kong

    2010-01-01

    Complete text of publication follows. Analytical description of an experimentally verified scheme leading to a phase-locked stimulated Brillouin scattering (SBS), used in a laser beam combination systems, is presented. The essential condition for the phase-locking effect for SBS is the fixation of the starting position and time of the acoustic Brillouin wave. It is shown that the starting position fixation of this acoustic wave may have its origin in a transient acoustic standing wave initiated by an arising optical interference field produced by the back-seeding concave mirror. This interference field leads to a stationary density modulation of the medium. However, the way to the formation of this density modulation leads via the acoustic standing wave. An appropriate solution, in the form of the standing wave, was obtained from solving the acoustic wave-equation using the electrostriction as a driving force. As a consequence of the damping term included in this equation the acoustic standing wave becomes gradually attenuated and contrary to the undamped solution published earlier, thus constitutes a truly transient phenomenon. Using a mathematical formalism similar to that which is used for the SBS description in the case of a random phase, the coupled equations describing the phase-locked SBS were derived. Contrary to the case without the back-seeding mirror, where the wave chosen from the thermal noise background subsequently plays the role of a trigger of the stimulated process, in this case it is replaced by the transient standing wave produced as a consequence of the presence of an optical interference field arisen in the focal region of the back-seeding concave mirror.

  3. Optoelectronic cross-injection locking of a dual-wavelength photonic integrated circuit for low-phase-noise millimeter-wave generation.

    Science.gov (United States)

    Kervella, Gaël; Van Dijk, Frederic; Pillet, Grégoire; Lamponi, Marco; Chtioui, Mourad; Morvan, Loïc; Alouini, Mehdi

    2015-08-01

    We report on the stabilization of a 90-GHz millimeter-wave signal generated from a fully integrated photonic circuit. The chip consists of two DFB single-mode lasers whose optical signals are combined on a fast photodiode to generate a largely tunable heterodyne beat note. We generate an optical comb from each laser with a microwave synthesizer, and by self-injecting the resulting signal, we mutually correlate the phase noise of each DFB and stabilize the beatnote on a multiple of the frequency delivered by the synthesizer. The performances achieved beat note linewidth below 30 Hz.

  4. High-speed clock recovery and demodulation using short pulse sources and phase-locked loop techniques

    DEFF Research Database (Denmark)

    Zibar, Darko

    2007-01-01

    clocktiming jitter, i.e. 3.5 ps at 40 Gb/s and 0.5 ps at 160 Gb/s. In the last part of the thesis, a novel phase-locked coherent optical phase demodulator with feedback and sampling, to be used in phase-modulated radio-over-fibre optical links, is also presented, theoretically investigated and experimentally...... demonstrated. It is experimentally shown that the proposed approach results in 18 dB of spur-free-dynamic range improve- ment compared to a traditional demodulator without feedback. A new time-domain, large signal, numerical model of the phase locked coherent demodulator is developed and shown...... loop with noise at a bit-rate of 160 Gb/s. It has been shown that it is important to reduce the time delay in the loop since it results in the increased timing jitter of the recovered clock signal. We also investigate the requirement for the free-running timing jitter of the local electrical...

  5. Phase-locked 3D3C-MRV measurements in a bi-stable fluidic oscillator

    Science.gov (United States)

    Wassermann, Florian; Hecker, Daniel; Jung, Bernd; Markl, Michael; Seifert, Avi; Grundmann, Sven

    2013-03-01

    In this work, the phase-resolved internal flow of a bi-stable fluidic oscillator was measured using phase-locked three-dimensional three-components magnetic resonance velocimetry (3D3C-MRV), also termed as 4D-MRV. A bi-stable fluidic oscillator converts a continuous inlet-mass flow into a jet alternating between two outlet channels and, as a consequence provides an unsteady, periodic flow. This actuator can therefore be used as flow-control actuator. Since data acquisition in a 3D volume takes up to several minutes, only a small portion of the data is acquired in each flow cycle for every time point of the flow cycle. The acquisition of the entire data set is segmented over many cycles of the periodic flow. This procedure allows to measure phase-averaged 3D3C velocity fields with a certain temporal resolution. However, the procedure requires triggering to the periodic nature of the flow. Triggering the MR scanner precisely on each flow cycle is one of the key issues discussed in this manuscript. The 4D-MRV data are compared to data measured using phase-locked laser Doppler anemometry and good agreement between the results is found. The validated 4D-MRV data is analyzed and the fluid-mechanic features and processes inside the fluidic oscillator are investigated and described, providing a detailed description of the internal jet-switching mechanism.

  6. A low spur, low jitter 10-GHz phase-locked loop in 0.13-μm CMOS technology

    International Nuclear Information System (INIS)

    Mei Niansong; Sun Yu; Lu Bo; Pan Yaohua; Huang Yumei; Hong Zhiliang

    2011-01-01

    This paper presents a 10-GHz low spur and low jitter phase-locked loop (PLL). An improved low phase noise VCO and a dynamic phase frequency detector with a short delay reset time are employed to reduce the noise of the PLL. We also discuss the methodology to optimize the high frequency prescaler's noise and the charge pump's current mismatch. The chip was fabricated in a SMIC 0.13-μm RF CMOS process with a 1.2-V power supply. The measured integrated RMS jitter is 757 fs (1 kHz to 10 MHz); the phase noise is -89 and -118.1 dBc/Hz at 10 kHz and 1 MHz frequency offset, respectively; and the reference frequency spur is below -77 dBc. The chip size is 0.32 mm 2 and the power consumption is 30.6 mW. (semiconductor integrated circuits)

  7. A New Built-in Self Test Scheme for Phase-Locked Loops Using Internal Digital Signals

    Science.gov (United States)

    Kim, Youbean; Kim, Kicheol; Kim, Incheol; Kang, Sungho

    Testing PLLs (phase-locked loops) is becoming an important issue that affects both time-to-market and production cost of electronic systems. Though a PLL is the most common mixed-signal building block, it is very difficult to test due to internal analog blocks and signals. In this paper, we propose a new PLL BIST (built-in self test) using the distorted frequency detector that uses only internal digital signals. The proposed BIST does not need to load any analog nodes of the PLL. Therefore, it provides an efficient defect-oriented structural test scheme, reduced area overhead, and improved test quality compared with previous approaches.

  8. An adaptive Phase-Locked Loop algorithm for faster fault ride through performance of interconnected renewable energy sources

    DEFF Research Database (Denmark)

    Hadjidemetriou, Lenos; Kyriakides, Elias; Blaabjerg, Frede

    2013-01-01

    Interconnected renewable energy sources require fast and accurate fault ride through operation in order to support the power grid when faults occur. This paper proposes an adaptive Phase-Locked Loop (adaptive dαβPLL) algorithm, which can be used for a faster and more accurate response of the grid...... side converter control of a renewable energy source, especially under fault ride through operation. The adaptive dαβPLL is based on modifying the control parameters of the dαβPLL according to the type and voltage characteristic of the grid fault with the purpose of accelerating the performance...

  9. Phase-lock loop of Grid-connected Voltage Source Converter under non-ideal grid condition

    DEFF Research Database (Denmark)

    Wang, Haojie; Sun, Hai; Han, Minxiao

    2015-01-01

    It is a normal practice that the DC micro-grid is connected to AC main grid through Grid-connected Voltage Source Converter (G-VSC) for voltage support. Accurate control of DC micro-grid voltage is difficult for G-VSC under unbalanced grid condition as the fundamental positive-sequence component...... and distorted system voltage the proposed PLL can accurately detect the fundamental positive-sequence component of grid voltage thus accurate control of DC micro-grid voltage can be realized....... phase information cannot be accurately tracked. Based on analysis of the cause of double-frequency ripple when unbalance exists in main grid, a phase-locked loop (PLL) detection technique is proposed. Under the conditions of unsymmetrical system voltage, varying system frequency, single-phase system...

  10. Absolute distance measurement by dual-comb interferometry with multi-channel digital lock-in phase detection

    International Nuclear Information System (INIS)

    Yang, Ruitao; Pollinger, Florian; Meiners-Hagen, Karl; Krystek, Michael; Bosse, Harald; Tan, Jiubin

    2015-01-01

    We present a dual-comb-based heterodyne multi-wavelength absolute interferometer capable of long distance measurements. The phase information of the various comb modes is extracted in parallel by a multi-channel digital lock-in phase detection scheme. Several synthetic wavelengths of the same order are constructed and the corresponding phases are averaged to deduce the absolute lengths with significantly reduced uncertainty. Comparison experiments with an incremental HeNe reference interferometer show a combined relative measurement uncertainty of 5.3 × 10 −7 at a measurement distance of 20 m. Combining the advantage of synthetic wavelength interferometry and dual-comb interferometry, our compact and simple approach provides sufficient precision for many industrial applications. (paper)

  11. Absolute distance measurement by dual-comb interferometry with multi-channel digital lock-in phase detection

    Science.gov (United States)

    Yang, Ruitao; Pollinger, Florian; Meiners-Hagen, Karl; Krystek, Michael; Tan, Jiubin; Bosse, Harald

    2015-08-01

    We present a dual-comb-based heterodyne multi-wavelength absolute interferometer capable of long distance measurements. The phase information of the various comb modes is extracted in parallel by a multi-channel digital lock-in phase detection scheme. Several synthetic wavelengths of the same order are constructed and the corresponding phases are averaged to deduce the absolute lengths with significantly reduced uncertainty. Comparison experiments with an incremental HeNe reference interferometer show a combined relative measurement uncertainty of 5.3 × 10-7 at a measurement distance of 20 m. Combining the advantage of synthetic wavelength interferometry and dual-comb interferometry, our compact and simple approach provides sufficient precision for many industrial applications.

  12. Feedforward and feedback control of locked mode phase and rotation in DIII-D with application to modulated ECCD experiments

    Science.gov (United States)

    Choi, W.; La Haye, R. J.; Lanctot, M. J.; Olofsson, K. E. J.; Strait, E. J.; Sweeney, R.; Volpe, F. A.; The DIII-D Team

    2018-03-01

    The toroidal phase and rotation of otherwise locked magnetic islands of toroidal mode number n  =  1 are controlled in the DIII-D tokamak by means of applied magnetic perturbations of n  =  1. Pre-emptive perturbations were applied in feedforward to ‘catch’ the mode as it slowed down and entrain it to the rotating field before complete locking, thus avoiding the associated major confinement degradation. Additionally, for the first time, the phase of the perturbation was optimized in real-time, in feedback with magnetic measurements, in order for the mode’s phase to closely match a prescribed phase, as a function of time. Experimental results confirm the capability to hold the mode in a given fixed-phase or to rotate it at up to 20 Hz with good uniformity. The control-coil currents utilized in the experiments agree with the requirements estimated by an electromechanical model. Moreover, controlled rotation at 20 Hz was combined with electron cyclotron current drive (ECCD) modulated at the same frequency. This is simpler than regulating the ECCD modulation in feedback with spontaneous mode rotation, and enables repetitive, reproducible ECCD deposition at or near the island O-point, X-point and locations in between, for careful studies of how this affects the island stability. Current drive was found to be radially misaligned relative to the island, and resulting growth and shrinkage of islands matched expectations of the modified Rutherford equation for some discharges presented here. Finally, simulations predict the as designed ITER 3D coils can entrain a small island at sub-10 Hz frequencies.

  13. Electron self-injection and acceleration in the bubble regime of laser-plasma interaction

    International Nuclear Information System (INIS)

    Kostyukov, I.; Nerush, E.

    2010-01-01

    Complete text of publication follows. The intense laser-plasma and beam-plasma interactions are highly nonlinear-phenomena, which besides being of fundamental interest, attract a great attention due to a number of important applications. One of the key applications is particle acceleration based on excitation of the strong plasma wakefield by laser pulse. In the linear regime of interaction when the laser intensity is low the plasma wake is the linear plasma wave. Moreover, the ponderomotive force of the laser pulse pushes out the plasma electrons from high intensity region leaving behind the laser pulse the plasma cavity - bubble, which is almost free from the plasma electrons. This is the bubble the laser-plasma interaction. Although the bubble propagates with velocity, which is close to speed of light, the huge charge of unshielded ions inside the plasma cavity can trap the cold plasma electrons. Moreover, the electrons are trapped in the accelerated phase of the bubble plasma field thereby leading to efficient electron acceleration. The electron self-injection is an important advantage of the plasma-based acceleration, which allows to exclude the beam loading system requiring accurate synchronization and additional space. The recent experiments have demonstrated high efficiency of the electron self-injection. The beam quality is often of crucial importance in many applications ranging from inertial confinement fusion to the x-ray free electron lasers. Despite a great interest there is still a little theory for relativistic electron dynamics in the plasma wake in multidimensional geometry including electron self-injection. The dynamics of the self-injected electrons can be roughly divided into three stage: (i) electron scattering by the laser pulse, (ii) electron trapping by the bubble, (iii) electron acceleration in the bubble. We developed two analytical models for electron dynamics in the bubble field and verify them by direct measurements of model parameters

  14. Spectral Narrowing of a Varactor-Integrated Resonant-Tunneling-Diode Terahertz Oscillator by Phase-Locked Loop

    Science.gov (United States)

    Ogino, Kota; Suzuki, Safumi; Asada, Masahiro

    2017-12-01

    Spectral narrowing of a resonant-tunneling-diode (RTD) terahertz oscillator, which is useful for various applications of terahertz frequency range, such as an accurate gas spectroscopy, a frequency reference in various communication systems, etc., was achieved with a phase-locked loop system. The oscillator is composed of an RTD, a slot antenna, and a varactor diode for electrical frequency tuning. The output of the RTD oscillating at 610 GHz was down-converted to 400 MHz by a heterodyne detection. The phase noise was transformed to amplitude noise by a balanced mixer and fed back into the varactor diode. The loop filter for a stable operation is discussed. The spectral linewidth of 18.6 MHz in free-running operation was reduced to less than 1 Hz by the feedback.

  15. A 3.96 GHz phase-locked loop for mode-1 MB-OFDM UWB hopping carrier generation

    Energy Technology Data Exchange (ETDEWEB)

    Zheng Yongzheng; Li Weinan; Xia Lingli; Huang Yumei; Hong Zhiliang, E-mail: yumeihuang@fudan.edu.c [State Key Laboratory of ASIC and System, Fudan University, Shanghai 201203 (China)

    2009-07-15

    A fully integrated phase-locked loop (PLL) is presented for a single quadrature output frequency of 3.96 GHz. The proposed PLL can be applied to mode-1 MB-OFDM UWB hopping carrier generation. An adaptive frequency calibration loop is incorporated into the PLL. The capacitance area in the loop filter is largely reduced through a capacitor multiplier. Implemented in a CMOS process, this PLL draws 13.0 mA current from a single 1.2 V supply while occupying 0.55 mm{sup 2} die area. Measurement results show that the PLL achieves a phase noise of-70 dBc/Hz at 10 kHz offset and -113 dBc/Hz at 1 MHz offset. The integrated RMS jitter from 1 kHz to 10 MHz is 2.2 ps. The reference spur level is less than -68 dBc.

  16. A 3.96 GHz phase-locked loop for mode-1 MB-OFDM UWB hopping carrier generation

    International Nuclear Information System (INIS)

    Zheng Yongzheng; Li Weinan; Xia Lingli; Huang Yumei; Hong Zhiliang

    2009-01-01

    A fully integrated phase-locked loop (PLL) is presented for a single quadrature output frequency of 3.96 GHz. The proposed PLL can be applied to mode-1 MB-OFDM UWB hopping carrier generation. An adaptive frequency calibration loop is incorporated into the PLL. The capacitance area in the loop filter is largely reduced through a capacitor multiplier. Implemented in a CMOS process, this PLL draws 13.0 mA current from a single 1.2 V supply while occupying 0.55 mm 2 die area. Measurement results show that the PLL achieves a phase noise of-70 dBc/Hz at 10 kHz offset and -113 dBc/Hz at 1 MHz offset. The integrated RMS jitter from 1 kHz to 10 MHz is 2.2 ps. The reference spur level is less than -68 dBc.

  17. The investigation of the phase-locking stability in linear arrays of Josephson junctions and arrays closed into a superconducting loop

    International Nuclear Information System (INIS)

    Darula, M.; Seidel, P.; Misanik, B.; Busse, F.; Heinz, E.; Benacka, S.

    1994-01-01

    The phase-locking stability is investigated theoretically in two structures: linear arrays of Josephson junctions shunted by resistive load and arrays closed into superconducting loop. In both cases the quasi-identical junctions are supposed to be in arrays. The stability as a function of spread in Josephson junction parameters as well as a function of other circuit parameters is investigated. Using Floquet theory it is shown that spread in critical currents of Josephson junction limit the stability of phase-locking state. From the simulations it follows that the phase-locking in arrays closed into superconducting loop is more stable against the spread in junction parameters than in the case of linear array of Josephson junctions. (orig.)

  18. Study of CMOS micromachined self-oscillating loop utilizing a phase-locked loop-driving circuit

    International Nuclear Information System (INIS)

    Li, Hsin-Chih; Tseng, Sheng-Hsiang; Lu, Michael S.-C.; Huang, Po-Chiun

    2012-01-01

    This work describes the design and characterization of integrated CMOS (complementary metal oxide semiconductor) oscillators comprising a capacitively transduced micromechanical resonator and a phase-locked loop (PLL) driving circuit. Three oscillator schemes are studied and compared, including direct feedback, direct feedback containing a PLL and hybrid direct feedback plus a PLL. PLL is known for its capability in automatic tuning and tracking of a reference signal. Inclusion of a PLL is beneficial for sustaining oscillations at resonant frequencies within its capture range. The micromechanical resonator has a measured resonant frequency of 117.3 kHz. The CMOS PLL circuit has a closed-loop bandwidth of 1.8 kHz with a capture range between 111 kHz and 118.4 kHz. The start-up times for oscillation are shortened in the two schemes utilizing a PLL, since it provides an initial driving signal at its free-running frequency. The lock-in time is also reduced by increasing the proportion of PLL drive in the hybrid scheme. The measured noises for the three oscillator schemes are similar with a value of −75 dB below the resonant peak at a 10 Hz offset. (paper)

  19. Self injection of foreign materials into the penis.

    Science.gov (United States)

    Ahmed, U; Freeman, A; Kirkham, A; Ralph, D J; Minhas, S; Muneer, A

    2017-02-01

    Injection of the subcutaneous tissues of the penis for enlargement of penile girth has been practised for many years by laypeople and medical practitioners alike. However, with recognition of the complications, the practice has died out. We report a series of five patients who presented having injected foreign materials into the subcutaneous tissues of their penises, including paraffin and mineral oils. Our patients had a variable time course of presentation ranging from 1 day following injection to over 26 years. Self-injection of the subcutaneous tissues of the penis is an unusual presentation for a penile mass but should be considered as a differential diagnosis in patients with a long latent period to presentation or with characteristic magnetic resonance imaging and histological appearances.

  20. Quantum noise locking

    International Nuclear Information System (INIS)

    McKenzie, Kirk; Mikhailov, Eugeniy E; Goda, Keisuke; Lam, Ping Koy; Grosse, Nicolai; Gray, Malcolm B; Mavalvala, Nergis; McClelland, David E

    2005-01-01

    Quantum optical states which have no coherent amplitude, such as squeezed vacuum states, cannot rely on standard readout techniques to generate error signals for control of the quadrature phase. Here we investigate the use of asymmetry in the quadrature variances to obtain a phase-sensitive readout and to lock the phase of a squeezed vacuum state, a technique which we call noise locking (NL). We carry out a theoretical derivation of the NL error signal and the associated stability of the squeezed and anti-squeezed lock points. Experimental data for the NL technique both in the presence and absence of coherent fields are shown, including a comparison with coherent locking techniques. Finally, we use NL to enable a stable readout of the squeezed vacuum state on a homodyne detector

  1. A K-Band Low-Power Phase Shifter Based on Injection Locked Oscillator in 0.13 μm CMOS Technology

    Science.gov (United States)

    Qiu, Qi-Lin; Yu, Xiao-Peng; Sui, Wen-Quan

    2017-11-01

    In this paper, the design challenges of the injection-locked oscillator (ILO)-based phase shifter are reviewed and analyzed. The key design considerations such as the operating frequency, locking range, and linearity of the phase shifters are analysed in detail. It is possible to optimize the phase shifter in certain parameters such as ultra-low power while meeting the requirements of a certain system. As a design example, a K-band phase shifter is implemented using a commercial 0.13 μm CMOS technology, where a conventional LC tank based topology is implemented but optimised with a good balance among power consumption, working range, sensitivity, and silicon area, etc. Measurement results show that the proposed phase shift is able to work at 22-23.4 GHz with a range of 180∘ while consuming 3.14 mW from a 1.2 V supply voltage.

  2. Use of phase-locking value in sensorimotor rhythm-based brain-computer interface: zero-phase coupling and effects of spatial filters.

    Science.gov (United States)

    Jian, Wenjuan; Chen, Minyou; McFarland, Dennis J

    2017-11-01

    Phase-locking value (PLV) is a potentially useful feature in sensorimotor rhythm-based brain-computer interface (BCI). However, volume conduction may cause spurious zero-phase coupling between two EEG signals and it is not clear whether PLV effects are independent of spectral amplitude. Volume conduction might be reduced by spatial filtering, but it is uncertain what impact this might have on PLV. Therefore, the goal of this study was to explore whether zero-phase PLV is meaningful and how it is affected by spatial filtering. Both amplitude and PLV feature were extracted in the frequency band of 10-15 Hz by classical methods using archival EEG data of 18 subjects trained on a two-target BCI task. The results show that with right ear-referenced data, there is meaningful long-range zero-phase synchronization likely involving the primary motor area and the supplementary motor area that cannot be explained by volume conduction. Another novel finding is that the large Laplacian spatial filter enhances the amplitude feature but eliminates most of the phase information seen in ear-referenced data. A bipolar channel using phase-coupled areas also includes both phase and amplitude information and has a significant practical advantage since fewer channels required.

  3. Observation of phase noise reduction in photonically synthesized sub-THz signals using a passively mode-locked laser diode and highly selective optical filtering

    DEFF Research Database (Denmark)

    Criado, A. R.; Acedo, P.; Carpintero, G.

    2012-01-01

    A Continuous Wave (CW) sub-THz photonic synthesis setup based on a single Passively Mode-Locked Laser Diode (PMLLD) acting as a monolithic Optical Frequency Comb Generator (OFCG) and highly selective optical filtering has been implemented to evaluate the phase noise performance of the generated sub...

  4. Phase locking of a 3.4 THz third-order distributed feedback quantum cascade laser using a room-temperature superlattice harmonic mixer

    NARCIS (Netherlands)

    Hayton, D. J.; Khudchencko, A.; Pavelyev, D. G.; Hovenier, J. N.; Baryshev, A.; Gao, J. R.; Kao, T. Y.; Hu, Q.; Reno, J. L.; Vaks, V.

    2013-01-01

    We report on the phase locking of a 3.4 THz third-order distributed feedback quantum cascade laser (QCL) using a room temperature GaAs/AlAs superlattice diode as both a frequency multiplier and an internal harmonic mixer. A signal-to-noise level of 60 dB is observed in the intermediate frequency

  5. Phase locking of a 3.4 THz third-order distributed feedback quantum cascade laser using a room-temperature superlattice harmonic mixer

    NARCIS (Netherlands)

    Hayton, D.J.; Khudchenko, A.; Pavelyev, D.G.; Hovenier, J.N.; Baryshev, A.; Gao, J.R.; Kao, T.Y.; Hu, Q.; Reno, J.L.; Vaks, V.

    2013-01-01

    We report on the phase locking of a 3.4 THz third-order distributed feedback quantum cascade laser (QCL) using a room temperature GaAs/AlAs superlattice diode as both a frequency multiplier and an internal harmonic mixer. A signal-to-noise level of 60?dB is observed in the intermediate frequency

  6. Volume Bragg grating external cavities for the passive phase locking of high-brightness diode laser arrays: theoretical and experimental study

    DEFF Research Database (Denmark)

    Paboeuf, David; Vijayakumar, Deepak; Jensen, Ole Bjarlin

    2011-01-01

    We describe the theoretical modeling of the external-cavity operation of a phase-locked array of diode lasers in two configurations, the self-imaging cavity based on the Talbot effect and the angular-filtering cavity. Complex filtering functions, such as the transmission or reflection of a volume...

  7. Theoretical and experimental investigation of a balanced phase-locked loop based clock recovery at a bit rate of 160 Gb/s

    DEFF Research Database (Denmark)

    Zibar, Darko; Oxenløwe, Leif Katsuo; Clausen, Anders

    2003-01-01

    This paper describes a mathematical model of a balanced opto-electronic phase-locked loop (OPLL), which is required to be very fast for some network applications. OPLL is investigated in terms of clock pulse width, loop filter gain and residuals of the balancing DC level. Based on the guidelines ...

  8. A widely tunable 10-μm quantum cascade laser phase-locked to a state-of-the-art mid-infrared reference for precision molecular spectroscopy

    Energy Technology Data Exchange (ETDEWEB)

    Sow, P. L. T.; Mejri, S.; Tokunaga, S. K.; Lopez, O.; Argence, B.; Chardonnet, C.; Darquié, B., E-mail: benoit.darquie@univ-paris13.fr [CNRS, UMR 7538, LPL, 93430 Villetaneuse (France); Université Paris 13, Sorbonne Paris Cité, Laboratoire de Physique des Lasers, 93430 Villetaneuse (France); Goncharov, A.; Amy-Klein, A.; Daussy, C. [Université Paris 13, Sorbonne Paris Cité, Laboratoire de Physique des Lasers, 93430 Villetaneuse (France); CNRS, UMR 7538, LPL, 93430 Villetaneuse (France)

    2014-06-30

    We report the coherent phase-locking of a quantum cascade laser (QCL) at 10-μm to the secondary frequency standard of this spectral region, a CO{sub 2} laser stabilized on a saturated absorption line of OsO{sub 4}. The stability and accuracy of the standard are transferred to the QCL resulting in a line width of the order of 10 Hz, and leading to the narrowest QCL to date. The locked QCL is then used to perform absorption spectroscopy spanning 6 GHz of NH{sub 3} and methyltrioxorhenium, two species of interest for applications in precision measurements.

  9. Automatic locking radioisotope camera lock

    International Nuclear Information System (INIS)

    Rosauer, P.J.

    1978-01-01

    The lock of the present invention secures the isotope source in a stored shielded condition in the camera until a positive effort has been made to open the lock and take the source outside of the camera and prevents disconnection of the source pigtail unless the source is locked in a shielded condition in the camera. It also gives a visual indication of the locked or possible exposed condition of the isotope source and prevents the source pigtail from being completely pushed out of the camera, even when the lock is released. (author)

  10. An improved phase-locked loop method for automatic resonance frequency tracing based on static capacitance broadband compensation for a high-power ultrasonic transducer.

    Science.gov (United States)

    Dong, Hui-juan; Wu, Jian; Zhang, Guang-yu; Wu, Han-fu

    2012-02-01

    The phase-locked loop (PLL) method is widely used for automatic resonance frequency tracing (ARFT) of high-power ultrasonic transducers, which are usually vibrating systems with high mechanical quality factor (Qm). However, a heavily-loaded transducer usually has a low Qm because the load has a large mechanical loss. In this paper, a series of theoretical analyses is carried out to detail why the traditional PLL method could cause serious frequency tracing problems, including loss of lock, antiresonance frequency tracing, and large tracing errors. The authors propose an improved ARFT method based on static capacitance broadband compensation (SCBC), which is able to address these problems. Experiments using a generator based on the novel method were carried out using crude oil as the transducer load. The results obtained have demonstrated the effectiveness of the novel method, compared with the conventional PLL method, in terms of improved tracing accuracy (±9 Hz) and immunity to antiresonance frequency tracing and loss of lock.

  11. Fiber-based coherent polarization beam combining with cascaded phase-locking and polarization-transforming controls

    Science.gov (United States)

    Yang, Yan; Geng, Chao; Li, Feng; Huang, Guan; Li, Xinyang

    2018-05-01

    In this paper, the fiber-based coherent polarization beam combining (CPBC) with cascaded phase-locking (PL) and polarization-transforming (PT) controls was proposed to combine imbalanced input beams where the number of the input beams is not binary, in which the PL control was performed using the piezoelectric-ring fiber-optic phase compensator, and the PT control was realized by the dynamic polarization controller, simultaneously. The principle of the proposed CPBC was introduced. The performance of the proposed CPBC was analyzed in comparison with the CPBC based on PL control and the CPBC based on PT control. The basic experiment of CPBC of three laser beams was carried out to validate the feasibility of the proposed CPBC, where cascaded controls of PL and PT were implemented based on stochastic parallel gradient descent algorithm. Simulation and experimental results show that the proposed CPBC incorporates the advantages of the two previous CPBC schemes and performs well in the closed loop. Moreover, the expansibility and the application of the proposed CPBC were validated by scaling the CPBC to combine seven laser beams. We believe that the proposed fiber-based CPBC with cascaded PL and PT controls has great potential in free space optical communications employing the multi-aperture receiver with asymmetric structure.

  12. Piezoelectric actuator based phase locking system to improve the dynamics of the control scheme for a heavy ion superconducting linac

    Energy Technology Data Exchange (ETDEWEB)

    Sahu, B.K., E-mail: bhuban@iuac.res.in [Inter University Accelerator Centre (IUAC), Aruna Asaf Ali Marg, New Delhi – 110 067 (India); Ahuja, R.; Kumar, Rajesh; Suman, S.K.; Mathuria, D.S.; Rai, A.; Patra, P.; Pandey, A.; Karmakar, J.; Chowdhury, G.K.; Dutt, R.N. [Inter University Accelerator Centre (IUAC), Aruna Asaf Ali Marg, New Delhi – 110 067 (India); Joshi, G. [Electronics Division, Bhabha Atomic Research Centre, Mumbai – 400 085 (India); Ghosh, S.; Kanjilal, D.; Roy, A. [Inter University Accelerator Centre (IUAC), Aruna Asaf Ali Marg, New Delhi – 110 067 (India)

    2015-03-21

    The superconducting heavy ion linear accelerator at Inter-University Accelerator Centre Delhi has been in operation since 2007. Initially, the superconducting niobium Quarter Wave Resonators (QWRs) in the linac were phase locked using a combination of electronic and mechanical controls which operated in fast (~10 μsec) and slow (~sec) time scales respectively. In this scheme, fast control was achieved through dynamic phase control whereas slow control of the frequency was done through the niobium tuner bellows installed at the drift tube end of the resonator and flexed using helium gas to change the resonance frequency. In order to improve the dynamics of this control system, an alternate scheme using piezoelectric actuator, instead of helium gas, to flex the same niobium bellows, has been implemented in the QWRs of the second and third accelerating modules of the linac. The piezoelectric actuator is used in closed loop along with the fast dynamic phase control scheme. The feedback loop of the piezoelectric control includes a dual control scheme - an integral control loop to arrest the slow drift, and the positive position feedback (PPF) based control loop to damp the microphonics. This control scheme has been found to arrest slow drifts in the resonator frequency more tightly along with damping of low frequency microphonics (~few tens of Hz) picked up by the resonator from its surrounding environment. This has substantially eased the load from the fast electronic control, resulting in the reduction of the radio frequency (RF) power requirement during operation. In addition, it has improved the stability of phase and amplitude of the QWRs. The details of the new scheme along with results obtained during the online run of the linac for beam acceleration are presented.

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

    Science.gov (United States)

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

    2012-07-24

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

  14. Numerical investigation of multichannel laser beam phase locking in turbulent atmosphere

    Energy Technology Data Exchange (ETDEWEB)

    Volkov, V A; Volkov, M V; Garanin, S G; Starikov, F A [Russian Federal Nuclear Center ' All-Russian Research Institute of Experimental Physics' , Sarov, Nizhnii Novgorod region (Russian Federation)

    2015-12-31

    The efficiency of coherent multichannel beam combining under focusing through a turbulent medium on a target in the cases of phase conjugation and target irradiation in the feedback loop is investigated numerically in various approximations. The conditions of efficient focusing of multichannel radiation on the target are found. It is shown that the coherent beam combining with target irradiation in the feedback loop, which does not require a reference beam and wavefront measurements, is as good as the phase conjugation approach in the efficiency of focusing. It is found that the main effect of focusing is provided by properly chosen phase shifts in the channels, whereas taking into account local wavefront tip tilts weakly affects the result. (control of laser radiation parameters)

  15. Formation of visual memories controlled by gamma power phase-locked to alpha oscillations

    Science.gov (United States)

    Park, Hyojin; Lee, Dong Soo; Kang, Eunjoo; Kang, Hyejin; Hahm, Jarang; Kim, June Sic; Chung, Chun Kee; Jiang, Haiteng; Gross, Joachim; Jensen, Ole

    2016-06-01

    Neuronal oscillations provide a window for understanding the brain dynamics that organize the flow of information from sensory to memory areas. While it has been suggested that gamma power reflects feedforward processing and alpha oscillations feedback control, it remains unknown how these oscillations dynamically interact. Magnetoencephalography (MEG) data was acquired from healthy subjects who were cued to either remember or not remember presented pictures. Our analysis revealed that in anticipation of a picture to be remembered, alpha power decreased while the cross-frequency coupling between gamma power and alpha phase increased. A measure of directionality between alpha phase and gamma power predicted individual ability to encode memory: stronger control of alpha phase over gamma power was associated with better memory. These findings demonstrate that encoding of visual information is reflected by a state determined by the interaction between alpha and gamma activity.

  16. Mobility function of a prosthetic knee joint with an automatic stance phase lock.

    Science.gov (United States)

    Andrysek, Jan; Klejman, Susan; Torres-Moreno, Ricardo; Heim, Winfried; Steinnagel, Bryan; Glasford, Shane

    2011-06-01

    There is a need for a prosthetic knee joint design that is technologically and functionally appropriate for use in developing countries. To develop and clinically evaluate a new type of stance phase controlled prosthetic knee joint that provides stance phase stability without inhibiting swing phase flexion. A crossover repeated measures study design comparing the new knee joint to the participant's conventional low- or high-end prosthetic knee joint. The new knee joint was fitted to fourteen individuals aged 15 to 67 years with unilateral lower limb amputations. Walk tests were performed to measure walking speed. Energy expenditure was estimated using the physiological cost index (PCI). Walking speeds with the new knee joint were on average 0.14 m/s faster than conventional low-end knees (p < 0.0001), but 0.07 m/s slower than conventional high-end prosthetic knees (p = 0.008). The PCI was similar across all three knee joint technologies (p = 0.276). Mobility function with the new knee joint, in terms of walking speed, was more closely matched to high-end than low-end prosthetic knee joints. Therefore, given its relatively simple design, the new stance phase control mechanism may offer a functional and cost effective solution for active transfemoral amputees. This paper describes a new type of prosthetic knee joint mechanism that is intended to be cost-effective while providing high-level stance phase function to active individuals with a transfemoral amputation. Initial clinical testing suggests that the new knee joint may have some functional advantages over existing technologies in this category.

  17. Dynamics of human subthalamic neuron phase-locking to motor and sensory cortical oscillations during movement.

    Science.gov (United States)

    Lipski, Witold J; Wozny, Thomas A; Alhourani, Ahmad; Kondylis, Efstathios D; Turner, Robert S; Crammond, Donald J; Richardson, Robert Mark

    2017-09-01

    Coupled oscillatory activity recorded between sensorimotor regions of the basal ganglia-thalamocortical loop is thought to reflect information transfer relevant to movement. A neuronal firing-rate model of basal ganglia-thalamocortical circuitry, however, has dominated thinking about basal ganglia function for the past three decades, without knowledge of the relationship between basal ganglia single neuron firing and cortical population activity during movement itself. We recorded activity from 34 subthalamic nucleus (STN) neurons, simultaneously with cortical local field potentials and motor output, in 11 subjects with Parkinson's disease (PD) undergoing awake deep brain stimulator lead placement. STN firing demonstrated phase synchronization to both low- and high-beta-frequency cortical oscillations, and to the amplitude envelope of gamma oscillations, in motor cortex. We found that during movement, the magnitude of this synchronization was dynamically modulated in a phase-frequency-specific manner. Importantly, we found that phase synchronization was not correlated with changes in neuronal firing rate. Furthermore, we found that these relationships were not exclusive to motor cortex, because STN firing also demonstrated phase synchronization to both premotor and sensory cortex. The data indicate that models of basal ganglia function ultimately will need to account for the activity of populations of STN neurons that are bound in distinct functional networks with both motor and sensory cortices and code for movement parameters independent of changes in firing rate. NEW & NOTEWORTHY Current models of basal ganglia-thalamocortical networks do not adequately explain simple motor functions, let alone dysfunction in movement disorders. Our findings provide data that inform models of human basal ganglia function by demonstrating how movement is encoded by networks of subthalamic nucleus (STN) neurons via dynamic phase synchronization with cortex. The data also

  18. The Differential Vector Phase-Locked Loop for Global Navigation Satellite System Signal Tracking

    Science.gov (United States)

    2014-06-01

    Precise Positioning”. Reports on Geodesy , 87(2):77–85, 2009. [6] Cellmer, S. “The Real-Time Precise Positioning Using MAFA Method”. Proceedings of...Wielgosz, and Z. Rzepecka. “Modified Ambiguity Function Approach for GPS Carrier Phase Positioning”. Journal of Geodesy , 84(4):267–275, 2010. [10] Chan, B...Journal of Geodesy , 70:330–341, 1996. [30] Hatch, R. “Instantaneous Ambiguity Resolution”. Proceedings of the International Symposium 107 on Kinematic

  19. Air lock

    International Nuclear Information System (INIS)

    Palkovich, P.; Gruber, J.; Madlener, W.

    1974-01-01

    The patent refers to an air lock system preferably for nuclear stations for the transport of heavy loads by means of a trolley on rails. For opening and closing of the air lock parts of the rails are removed, e.g. by a second rail system perpendicular to the main rails. (P.K.)

  20. Applying the Taguchi Method for Investigating the Phase-Locked Loop Dynamics Affected by Hybrid Storage System Parameters

    Directory of Open Access Journals (Sweden)

    Mostafa Ahmadzadeh

    2018-01-01

    Full Text Available Storage systems play an important role in performance of micro-grids. Storage systems may decrease fluctuations caused by periodic and unpredictable nature of distributed generation resource. Some micro-grids are connected to the network via a grid-interface converter. The phase-locked loop (PLL is a commonly technique for the grid synchronization of network-connected converters. Various parameters affect the stability of PLL (including the network-side and microgrid-side parameters. The effect of the micro-grid-side parameters on the stability of the PLL has not been studied so far. In this paper, the stability of PLL influenced by microgrid-side parameters has been evaluated after a detailed analytical modeling of micro-grid components (including the production power fluctuations, energy storage system, microgrid-side loads, controller parameters etc.. This paper proposes two new stability analysis criteria for PLL affected by micro-grid and hybrid storage system parameters. Using proposed criteria for stability of PLL, optimized rate of micro-grid and hybrid storage system parameters are obtained using statistical methods (Taguchi approach. Finally, behavior of PLL affected by hybrid storage system is investigated. The simulation results and eigenvalues analysis confirm the theoretical analysis and proposed criteria.

  1. 3D pressure imaging of an aircraft propeller blade-tip flow by phase-locked stereoscopic PIV

    Energy Technology Data Exchange (ETDEWEB)

    Ragni, D.; Oudheusden, B.W. van; Scarano, F. [Delft University of Technology, Faculty of Aerospace Engineering, Delft (Netherlands)

    2012-02-15

    The flow field at the tip region of a scaled DHC Beaver aircraft propeller, running at transonic speed, has been investigated by means of a multi-plane stereoscopic particle image velocimetry setup. Velocity fields, phase-locked with the blade rotational motion, are acquired across several planes perpendicular to the blade axis and merged to form a 3D measurement volume. Transonic conditions have been reached at the tip region, with a revolution frequency of 19,800 rpm and a relative free-stream Mach number of 0.73 at the tip. The pressure field and the surface pressure distribution are inferred from the 3D velocity data through integration of the momentum Navier-Stokes equation in differential form, allowing for the simultaneous flow visualization and the aerodynamic loads computation, with respect to a reference frame moving with the blade. The momentum and pressure data are further integrated by means of a contour-approach to yield the aerodynamic sectional force components as well as the blade torsional moment. A steady Reynolds averaged Navier-Stokes numerical simulation of the entire propeller model has been used for comparison to the measurement data. (orig.)

  2. 3D pressure imaging of an aircraft propeller blade-tip flow by phase-locked stereoscopic PIV

    Science.gov (United States)

    Ragni, D.; van Oudheusden, B. W.; Scarano, F.

    2012-02-01

    The flow field at the tip region of a scaled DHC Beaver aircraft propeller, running at transonic speed, has been investigated by means of a multi-plane stereoscopic particle image velocimetry setup. Velocity fields, phase-locked with the blade rotational motion, are acquired across several planes perpendicular to the blade axis and merged to form a 3D measurement volume. Transonic conditions have been reached at the tip region, with a revolution frequency of 19,800 rpm and a relative free-stream Mach number of 0.73 at the tip. The pressure field and the surface pressure distribution are inferred from the 3D velocity data through integration of the momentum Navier-Stokes equation in differential form, allowing for the simultaneous flow visualization and the aerodynamic loads computation, with respect to a reference frame moving with the blade. The momentum and pressure data are further integrated by means of a contour-approach to yield the aerodynamic sectional force components as well as the blade torsional moment. A steady Reynolds averaged Navier-Stokes numerical simulation of the entire propeller model has been used for comparison to the measurement data.

  3. Phase locking of an S-band wide-gap klystron amplifier with high power injection driven by a relativistic backward wave oscillator

    Energy Technology Data Exchange (ETDEWEB)

    Bai Xianchen; Zhang Jiande; Yang Jianhua; Jin Zhenxing [College of Optoelectronic Science and Engineering, National University of Defense Technology, Changsha 410073 (China)

    2012-12-15

    Theoretical analyses and preliminary experiments on the phase-locking characteristics of an inductively loaded 2-cavity wide-gap klystron amplifier (WKA) with high power injection driven by a GW-class relativistic backward wave oscillator (RBWO) are presented. Electric power of the amplifier and oscillator is supplied by a single accelerator being capable of producing dual electron beams. The well phase-locking effect of the RBWO-WKA system requires the oscillator have good frequency reproducibility and stability from pulse to pulse. Thus, the main switch of the accelerator is externally triggered to stabilize the diode voltage and then the working frequency. In the experiment, frequency of the WKA is linearly locked by the RBWO. With a diode voltage of 530 kV and an input power of {approx}22 MW, an output power of {approx}230 MW with the power gain of {approx}10.2 dB is obtained from the WKA. As the main switch is triggered, the relative phase difference between the RBWO and the WKA is less than {+-}15 Degree-Sign in a single shot, and phase jitter of {+-}11 Degree-Sign is obtained within a series of shots with duration of about 40 ns.

  4. Phase locking of an S-band wide-gap klystron amplifier with high power injection driven by a relativistic backward wave oscillator

    Science.gov (United States)

    Bai, Xianchen; Zhang, Jiande; Yang, Jianhua; Jin, Zhenxing

    2012-12-01

    Theoretical analyses and preliminary experiments on the phase-locking characteristics of an inductively loaded 2-cavity wide-gap klystron amplifier (WKA) with high power injection driven by a GW-class relativistic backward wave oscillator (RBWO) are presented. Electric power of the amplifier and oscillator is supplied by a single accelerator being capable of producing dual electron beams. The well phase-locking effect of the RBWO-WKA system requires the oscillator have good frequency reproducibility and stability from pulse to pulse. Thus, the main switch of the accelerator is externally triggered to stabilize the diode voltage and then the working frequency. In the experiment, frequency of the WKA is linearly locked by the RBWO. With a diode voltage of 530 kV and an input power of ˜22 MW, an output power of ˜230 MW with the power gain of ˜10.2 dB is obtained from the WKA. As the main switch is triggered, the relative phase difference between the RBWO and the WKA is less than ±15° in a single shot, and phase jitter of ±11° is obtained within a series of shots with duration of about 40 ns.

  5. The Thermal Phase Curve Offset on Tidally and Nontidally Locked Exoplanets: A Shallow Water Model

    Energy Technology Data Exchange (ETDEWEB)

    Penn, James; Vallis, Geoffrey K, E-mail: jp492@exeter.ac.uk, E-mail: g.vallis@exeter.ac.uk [University of Exeter, Exeter, Devon (United Kingdom)

    2017-06-20

    Using a shallow water model with time-dependent forcing, we show that the peak of an exoplanet thermal phase curve is, in general, offset from the secondary eclipse when the planet is rotating. That is, the planetary hot spot is offset from the point of maximal heating (the substellar point) and may lead or lag the forcing; the extent and sign of the offset are functions of both the rotation rate and orbital period of the planet. We also find that the system reaches a steady state in the reference frame of the moving forcing. The model is an extension of the well-studied Matsuno–Gill model into a full spherical geometry and with a planetary-scale translating forcing representing the insolation received on an exoplanet from a host star. The speed of the gravity waves in the model is shown to be a key metric in evaluating the phase curve offset. If the velocity of the substellar point (relative to the planet’s surface) exceeds that of the gravity waves, then the hot spot will lag the substellar point, as might be expected by consideration of forced gravity wave dynamics. However, when the substellar point is moving slower than the internal wave speed of the system, the hottest point may lead the passage of the forcing. We provide an interpretation of this result by consideration of the Rossby and Kelvin wave dynamics, as well as, in the very slowly rotating case, a one-dimensional model that yields an analytic solution. Finally, we consider the inverse problem of constraining planetary rotation rate from an observed phase curve.

  6. Aspects of the Color Flavor Locking phase of QCD in the Nambu-Jona Lasinio approximation

    CERN Document Server

    Casalbuoni, Roberto; Nardulli, Giuseppe; Ruggieri, Marco

    2003-01-01

    We study two aspects of the CFL phase of QCD in the NJL approximation. The first one is the issue of the dependence on \\mu of the ultraviolet cutoff in the gap equation, which is solved allowing a running coupling constant. The second one is the dependence of the gap on the strange quark mass; using the high density effective theory we perform an expansion in the parameter (m_s/\\mu)^2 after checking that its numerical validity is very good already at first order.

  7. Ka Band Phase Locked Loop Oscillator Dielectric Resonator Oscillator for Satellite EHF Band Receiver

    Directory of Open Access Journals (Sweden)

    S. Coco

    2008-01-01

    Full Text Available This paper describes the design and fabrication of a Ka Band PLL DRO having a fundamental oscillation frequency of 19.250 GHz, used as local oscillator in the low-noise block of a down converter (LNB for an EHF band receiver. Apposite circuital models have been created to describe the behaviour of the dielectric resonator and of the active component used in the oscillator core. The DRO characterization and measurements have shown very good agreement with simulation results. A good phase noise performance is obtained by using a very high Q dielectric resonator.

  8. A Fixed-Point Phase Lock Loop in a Software Defined Radio

    Science.gov (United States)

    2002-09-01

    code from a simulation model. This feature will allow easy implementation on an FPGA as C can be easily converted to VHDL , the language required...this is equivalent to the MATLAB code implementation in Appendix A. The PD takes the input signal 40 and multiplies it by the in-phase and...stop to 60 mph in 3.1 seconds (the fastest production car ever built is the Porsche Carrera twin turbo which was tested at 0-60 mph in 3.1 seconds

  9. Moving Average Filter-Based Phase-Locked Loops: Performance Analysis and Design Guidelines

    DEFF Research Database (Denmark)

    Golestan, Saeed; Ramezani, Malek; Guerrero, Josep M.

    2014-01-01

    this challenge, incorporating moving average filter(s) (MAF) into the PLL structure has been proposed in some recent literature. A MAF is a linear-phase finite impulse response filter which can act as an ideal low-pass filter, if certain conditions hold. The main aim of this paper is to present the control...... design guidelines for a typical MAF-based PLL. The paper starts with the general description of MAFs. The main challenge associated with using the MAFs is then explained, and its possible solutions are discussed. The paper then proceeds with a brief overview of the different MAF-based PLLs. In each case......, the PLL block diagram description is shown, the advantages and limitations are briefly discussed, and the tuning approach (if available) is evaluated. The paper then presents two systematic methods to design the control parameters of a typical MAF-based PLL: one for the case of using a proportional...

  10. Homodyne locking of a squeezer.

    Science.gov (United States)

    Heurs, M; Petersen, I R; James, M R; Huntington, E H

    2009-08-15

    We report on the successful implementation of an approach to locking the frequencies of an optical parametric oscillator (OPO)-based squeezed-vacuum source and its driving laser. The technique allows the simultaneous measurement of the phase shifts induced by a cavity, which may be used for the purposes of frequency locking, as well as the simultaneous measurement of the sub-quantum-noise-limited (sub-QNL) phase quadrature output of the OPO. The homodyne locking technique is cheap, easy to implement, and has the distinct advantage that subsequent homodyne measurements are automatically phase locked. The homodyne locking technique is also unique in that it is a sub-QNL frequency discriminator.

  11. Neural basis of postural focus effect on concurrent postural and motor tasks: phase-locked electroencephalogram responses.

    Science.gov (United States)

    Huang, Cheng-Ya; Zhao, Chen-Guang; Hwang, Ing-Shiou

    2014-11-01

    Dual-task performance is strongly affected by the direction of attentional focus. This study investigated neural control of a postural-suprapostural procedure when postural focus strategy varied. Twelve adults concurrently conducted force-matching and maintained stabilometer stance with visual feedback on ankle movement (visual internal focus, VIF) and on stabilometer movement (visual external focus, VEF). Force-matching error, dynamics of ankle and stabilometer movements, and event-related potentials (ERPs) were registered. Postural control with VEF caused superior force-matching performance, more complex ankle movement, and stronger kinematic coupling between the ankle and stabilometer movements than postural control with VIF. The postural focus strategy also altered ERP temporal-spatial patterns. Postural control with VEF resulted in later N1 with less negativity around the bilateral fronto-central and contralateral sensorimotor areas, earlier P2 deflection with more positivity around the bilateral fronto-central and ipsilateral temporal areas, and late movement-related potential commencing in the left frontal-central area, as compared with postural control with VIF. The time-frequency distribution of the ERP principal component revealed phase-locked neural oscillations in the delta (1-4Hz), theta (4-7Hz), and beta (13-35Hz) rhythms. The delta and theta rhythms were more pronounced prior to the timing of P2 positive deflection, and beta rebound was greater after the completion of force-matching in VEF condition than VIF condition. This study is the first to reveal the neural correlation of postural focusing effect on a postural-suprapostural task. Postural control with VEF takes advantage of efficient task-switching to facilitate autonomous postural response, in agreement with the "constrained-action" hypothesis. Copyright © 2014 Elsevier B.V. All rights reserved.

  12. Prescribing and using self-injectable antiretrovirals: How concordant are physician and patient perspectives?

    OpenAIRE

    Cohen Calvin; Fisher Martin; Youle Michael; Kulasegaram Ranjababu; Fumaz Carmina R; Clotet Bonaventura; Katlama Christine; Kovacs Colin; Horne Robert; Slim Jihad; Shalit Peter; Cooper Vanessa; Tsoukas Christos

    2009-01-01

    Abstract Background The selection of agents for any treatment regimen is in part influenced by physician and patient attitudes. This study investigated attitudinal motivators and barriers to the use of self-injectable antiretroviral agents among physicians and patients and measured the degree of concordance between physician and patient perspectives. Methods Attitudes toward prescribing and usage of self-injectable antiretroviral therapy (SIAT) were assessed by structured interview in 2 cohor...

  13. Two-wavelength, passive self-injection-controlled operation of diode-pumped cw Yb-doped crystal lasers.

    Science.gov (United States)

    Louyer, Yann; Wallerand, Jean-Pierre; Himbert, Marc; Deneva, Margarita; Nenchev, Marin

    2003-09-20

    We demonstrate and investigate a peculiar mode of cw Yb3+-doped crystal laser operation when two emissions, at two independently tunable wavelengths, are simultaneously produced. Both emissions are generated from a single pumped volume and take place in either a single beam or spatially separated beams. The laser employs original two-channel cavities that use a passive self-injection-locking (PSIL) control to reduce intracavity loss. The advantages of the application of the PSIL technique and some limitations are shown. The conditions for two-wavelength multimode operation of the cw quasi-three-level diode-pumped Yb3+ lasers and the peculiarity of such an operation are carried out both theoretically and experimentally. The results reported are based on the example of a Yb3+:GGG laser but similar results are also obtained with a Yb3+:YAG laser. The laser operates in the 1023-1033-nm (1030-1040-nm) range with a total output power of 0.4 W. A two-wavelength, single longitudinal mode generation is also obtained.

  14. Flattened optical frequency-locked multi-carrier generation by cascading one DML and one phase modulator driven by different RF frequency clocks

    International Nuclear Information System (INIS)

    Li, Xinying; Yu, Jianjun; Zhang, Junwen; Chi, Nan

    2013-01-01

    We propose a novel scheme for flattened optical frequency-locked multi-carrier generation based on one directly modulated laser (DML) and one phase modulator (PM) in cascade driven by different sinusoidal radio-frequency (RF) clocks. We experimentally demonstrate that when the clock frequencies for the cascaded DML and the PM are respectively 12.5 GHz and 25 GHz, over 24 optical subcarriers can be generated with 12.5-GHz frequency spacing and amplitude fluctuation less than 3 dB. Furthermore, the number of generated optical subcarriers can be further increased when we increase the driving power for the DML. (letter)

  15. Near-GeV-energy laser-wakefield acceleration of self-injected electrons in a centimeter-scale plasma channel

    International Nuclear Information System (INIS)

    Tsung, F.S.; Narang, Ritesh; Joshi, C.; Mori, W. B.; Fonseca, R. A.; Silva, L.O.

    2004-01-01

    The first three-dimensional, particle-in-cell (PIC) simulations of laser-wakefield acceleration of self-injected electrons in a 0.84 cm long plasma channel are reported. The frequency evolution of the initially 50 fs (FWHM) long laser pulse by photon interaction with the wake followed by plasma dispersion enhances the wake which eventually leads to self-injection of electrons from the channel wall. This first bunch of electrons remains spatially highly localized. Its phase space rotation due to slippage with respect to the wake leads to a monoenergetic bunch of electrons with a central energy of 0.26 GeV after 0.55 cm propagation. At later times, spatial bunching of the laser enhances the acceleration of a second bunch of electrons to energies up to 0.84 GeV before the laser pulse intensity is significantly reduced

  16. Self-injection threshold in self-guided laser wakefield accelerators

    Directory of Open Access Journals (Sweden)

    S. P. D. Mangles

    2012-01-01

    Full Text Available A laser pulse traveling through a plasma can excite large amplitude plasma waves that can be used to accelerate relativistic electron beams in a very short distance—a technique called laser wakefield acceleration. Many wakefield acceleration experiments rely on the process of wave breaking, or self-injection, to inject electrons into the wave, while other injection techniques rely on operation without self-injection. We present an experimental study into the parameters, including the pulse energy, focal spot quality, and pulse power, that determine whether or not a wakefield accelerator will self-inject. By taking into account the processes of self-focusing and pulse compression we are able to extend a previously described theoretical model, where the minimum bubble size k_{p}r_{b} required for trapping is not constant but varies slowly with density and find excellent agreement with this model.

  17. Avoiding lock-in

    DEFF Research Database (Denmark)

    Henriksen, Ingrid

    1999-01-01

    The paper investigates the initial phase of the cooperative organisation of agricultural processing firms in Denmark. It argues that the variations observed can be explained within the framework of the theory of industrial organisation. The focus is on the success of cooperative creameries. In 19...... of gathering information and of preserving and transporting a perishable product, were ideally suited to overcome the problems of potential lock-in and of asymmetric information...

  18. Heterodyne interferometer laser source with a pair of two phase locked loop coupled He–Ne lasers by 632.8 nm

    International Nuclear Information System (INIS)

    Sternkopf, C; Diethold, C; Gerhardt, U; Manske, E; Wurmus, J

    2012-01-01

    Two He–Ne lasers are frequency and phase coupled by phase locking loop technique for a heterodyne laser interferometer. The heterodyne He–Ne laser is built of stabilized commercially used laser tubes. The two lasers create a high frequency stable heterodyne laser source with an output power of 2 mW. The laser source is coupled by two fibers (one fiber per laser) to the heterodyne laser head. This paper describes the configuration and the control theory basics of the laser system. The experimental setup and the equipment used are also described. First, experimental results with different parameters are represented. Then we discuss a novel heterodyne laser source which has achieved a master laser frequency stability of Δf 1 /f 1 = 1 · 10 −8 and a beat frequency stability of approximately Δf beat /f beat ≈ 4.5 · 10 −5 . (paper)

  19. An unusual delayed complication of paraffin self-injection for penile girth augmentation.

    Science.gov (United States)

    De Siati, Mario; Selvaggio, Oscar; Di Fino, Giuseppe; Liuzzi, Giuseppe; Massenio, Paolo; Sanguedolce, Francesca; Carrieri, Giuseppe; Cormio, Luigi

    2013-12-01

    Penile self-injection of various oils is still carried out among Eastern Europe people for penile girth augmentation despite the potential destructive complications of this practice are well known. Penile reactions to such foreign bodies include scarring, abscess formation, ulceration, and even Fournier's gangrene; voiding problems due to mineral oil self-injection have been reported only once. To our knowledge, we describe the first case of paraffin self-injection for penile girth augmentation presenting with acute urinary retention. A 27-year-old Romanian man presented with severe penile pain and acute urinary retention five years after having practiced repeated penile self-injections of paraffin for penile girth augmentation. The penile shaft was massively enlarged, fibrotic and phymotic; urethral catheterization failed due to severe stricture of the proximal pendulum urethra. The patients refused placement of a suprapubic catheter and underwent immediate penile surgical exploration. The scarred tissue between dartos and Buck's fascia and a fibrotic ring occluding the urethra were removed and the penile skin reconstructed. Pathology confirmed the diagnosis of paraffinoma. The patient resumed normal voiding immediately after catheter removal on second postoperative day; he was very pleased with cosmetic, sexual and voiding results at six weeks, six months and 1 year follow-up. The present report describes a novel complication of penile self-injection for penile girth augmentation. Because of the increasing number of patients seeking penile augmentation, physicians dealing with sexual medicine should pay more attention to such request to prevent the use of non medical treatments that can turn into medical disasters.

  20. Theory for passive mode-locking in semiconductor laser structures including the effects of self-phase modulation, dispersion and pulse collisions

    NARCIS (Netherlands)

    Koumans, R.G.M.P.; Roijen, van R.

    1996-01-01

    We present a theory for passive mode-locking in semiconductor laser structures using a semiconductor laser amplifier and absorber. The mode-locking system is described in terms of the different elements in the semiconductor laser structure. We derive mode-locking conditions and show how other

  1. A wide range ultra-low power Phase-Locked Loop with automatic frequency setting in 130 nm CMOS technology for data serialisation

    International Nuclear Information System (INIS)

    Firlej, M.; Fiutowski, T.; Idzik, M.; Moroń, J.; Świentek, K.

    2015-01-01

    The design and measurements results of a wide frequency range ultra-low power Phase-Locked Loop (PLL) for applications in readout systems of particle physics detectors are presented. The PLL was fabricated in a 130 nm CMOS technology. To allow the implementation of different data serialisation schemes multiple division factors (6, 8, 10, 16) were implemented in the PLL feedback loop. The main PLL block—VCO works in 16 frequency ranges/modes, switched either manually or automatically. A dedicated automatic frequency mode switching circuit was developed to allow simple frequency tuning. Although the PLL was designed and simulated for a frequency range of 30 MHz–3 GHz, due to the SLVS interface limits, the measurements were done only up to 1.3 GHz. The full PLL functionality was experimentally verified, confirming a very low and frequency scalable power consumption (0.7 mW at 1 GHz)

  2. A wide range ultra-low power Phase-Locked Loop with automatic frequency setting in 130 nm CMOS technology for data serialisation

    Science.gov (United States)

    Firlej, M.; Fiutowski, T.; Idzik, M.; Moroń, J.; Świentek, K.

    2015-12-01

    The design and measurements results of a wide frequency range ultra-low power Phase-Locked Loop (PLL) for applications in readout systems of particle physics detectors are presented. The PLL was fabricated in a 130 nm CMOS technology. To allow the implementation of different data serialisation schemes multiple division factors (6, 8, 10, 16) were implemented in the PLL feedback loop. The main PLL block—VCO works in 16 frequency ranges/modes, switched either manually or automatically. A dedicated automatic frequency mode switching circuit was developed to allow simple frequency tuning. Although the PLL was designed and simulated for a frequency range of 30 MHz-3 GHz, due to the SLVS interface limits, the measurements were done only up to 1.3 GHz. The full PLL functionality was experimentally verified, confirming a very low and frequency scalable power consumption (0.7 mW at 1 GHz).

  3. Global distribution of GPS losses of phase lock and total electron content slips during the 2005 May 15 and the 2003 November 20 magnetic storms

    Science.gov (United States)

    Yasyukevich, Yuriy; Astafeva, Elvira; Givetev, Ilya; Maksikov, Aleksey

    2015-12-01

    Using data of worldwide network of GPS receivers we investigated losses of GPS phase lock (LoL) during two strong magnetic storms. At fundamental L1 frequency, LoL density is found to increase up to 0.25 % and at L2 frequency the increase is up to 3 %. This is several times as much compared with the background level. During the 2003 November 20 magnetic storm, the number of total electron content (TEC) slips exceeded the background level ~50 times. During superstorms, the most number of GPS LoL is observed at low and high latitudes. At the same time, the area of numerous TEC slips correspond to auroral oval boundaries.

  4. Elementary properties of Ca(2+) channels and their influence on multivesicular release and phase-locking at auditory hair cell ribbon synapses.

    Science.gov (United States)

    Magistretti, Jacopo; Spaiardi, Paolo; Johnson, Stuart L; Masetto, Sergio

    2015-01-01

    Voltage-gated calcium (Cav1.3) channels in mammalian inner hair cells (IHCs) open in response to sound and the resulting Ca(2+) entry triggers the release of the neurotransmitter glutamate onto afferent terminals. At low to mid sound frequencies cell depolarization follows the sound sinusoid and pulses of transmitter release from the hair cell generate excitatory postsynaptic currents (EPSCs) in the afferent fiber that translate into a phase-locked pattern of action potential activity. The present article summarizes our current understanding on the elementary properties of single IHC Ca(2+) channels, and how these could have functional implications for certain, poorly understood, features of synaptic transmission at auditory hair cell ribbon synapses.

  5. Elementary properties of Ca2+ channels and their influence on multivesicular release and phase-locking at auditory hair cell ribbon synapses

    Science.gov (United States)

    Magistretti, Jacopo; Spaiardi, Paolo; Johnson, Stuart L.; Masetto, Sergio

    2015-01-01

    Voltage-gated calcium (Cav1.3) channels in mammalian inner hair cells (IHCs) open in response to sound and the resulting Ca2+ entry triggers the release of the neurotransmitter glutamate onto afferent terminals. At low to mid sound frequencies cell depolarization follows the sound sinusoid and pulses of transmitter release from the hair cell generate excitatory postsynaptic currents (EPSCs) in the afferent fiber that translate into a phase-locked pattern of action potential activity. The present article summarizes our current understanding on the elementary properties of single IHC Ca2+ channels, and how these could have functional implications for certain, poorly understood, features of synaptic transmission at auditory hair cell ribbon synapses. PMID:25904847

  6. 5.5 W near-diffraction-limited power from resonant leaky-wave coupled phase-locked arrays of quantum cascade lasers

    International Nuclear Information System (INIS)

    Kirch, J. D.; Chang, C.-C.; Boyle, C.; Mawst, L. J.; Botez, D.; Lindberg, D.; Earles, T.

    2015-01-01

    Five, 8.36 μm-emitting quantum-cascade lasers (QCLs) have been monolithically phase-locked in the in-phase array mode via resonant leaky-wave coupling. The structure is fabricated by etch and regrowth which provides large index steps (Δn = 0.10) between antiguided-array elements and interelement regions. Such high index contrast photonic-crystal (PC) lasers have more than an order of magnitude higher index contrast than PC-distributed feedback lasers previously used for coherent beam combining in QCLs. Absorption loss to metal layers inserted in the interelement regions provides a wide (∼1.0 μm) range in interelement width over which the resonant in-phase mode is strongly favored to lase. Room-temperature, in-phase-mode operation with ∼2.2 kA/cm 2 threshold-current density is obtained from 105 μm-wide aperture devices. The far-field beam pattern has lobewidths 1.65× diffraction limit (D.L.) and 82% of the light in the main lobe, up to 1.8× threshold. Peak pulsed near-D.L. power of 5.5 W is obtained, with 4.5 W emitted in the main lobe. Means of how to increase the device internal efficiency are discussed

  7. Performance of arm locking in LISA

    International Nuclear Information System (INIS)

    McKenzie, Kirk; Spero, Robert E.; Shaddock, Daniel A.

    2009-01-01

    For the Laser Interferometer Space Antenna (LISA) to reach its design sensitivity, the coupling of the free-running laser frequency noise to the signal readout must be reduced by more than 14 orders of magnitude. One technique employed to reduce the laser frequency noise will be arm locking, where the laser frequency is locked to the LISA arm length. In this paper we detail an implementation of arm locking. We investigate orbital effects (changing arm lengths and Doppler frequencies), the impact of errors in the Doppler knowledge that can cause pulling of the laser frequency, and the noise limit of arm locking. Laser frequency pulling is examined in two regimes: at lock acquisition and in steady state. The noise performance of arm locking is calculated with the inclusion of the dominant expected noise sources: ultrastable oscillator (clock) noise, spacecraft motion, and shot noise. We find that clock noise and spacecraft motion limit the performance of dual arm locking in the LISA science band. Studying these issues reveals that although dual arm locking [A. Sutton and D. A. Shaddock, Phys. Rev. D 78, 082001 (2008)] has advantages over single (or common) arm locking in terms of allowing high gain, it has disadvantages in both laser frequency pulling and noise performance. We address this by proposing a modification to the dual arm-locking sensor, a hybrid of common and dual arm-locking sensors. This modified dual arm-locking sensor has the laser frequency pulling characteristics and low-frequency noise coupling of common arm locking, but retains the control system advantages of dual arm locking. We present a detailed design of an arm-locking controller and perform an analysis of the expected performance when used with and without laser prestabilization. We observe that the sensor phase changes beneficially near unity-gain frequencies of the arm-locking controller, allowing a factor of 10 more gain than previously believed, without degrading stability. With a time

  8. Microcontroller-based locking in optics experiments

    International Nuclear Information System (INIS)

    Huang, K.; Le Jeannic, H.; Ruaudel, J.; Morin, O.; Laurat, J.

    2014-01-01

    Optics experiments critically require the stable and accurate locking of relative phases between light beams or the stabilization of Fabry-Perot cavity lengths. Here, we present a simple and inexpensive technique based on a stand-alone microcontroller unit to perform such tasks. Easily programmed in C language, this reconfigurable digital locking system also enables automatic relocking and sequential functioning. Different algorithms are detailed and applied to fringe locking and to low- and high-finesse optical cavity stabilization, without the need of external modulations or error signals. This technique can readily replace a number of analog locking systems advantageously in a variety of optical experiments

  9. Microcontroller-based locking in optics experiments.

    Science.gov (United States)

    Huang, K; Le Jeannic, H; Ruaudel, J; Morin, O; Laurat, J

    2014-12-01

    Optics experiments critically require the stable and accurate locking of relative phases between light beams or the stabilization of Fabry-Perot cavity lengths. Here, we present a simple and inexpensive technique based on a stand-alone microcontroller unit to perform such tasks. Easily programmed in C language, this reconfigurable digital locking system also enables automatic relocking and sequential functioning. Different algorithms are detailed and applied to fringe locking and to low- and high-finesse optical cavity stabilization, without the need of external modulations or error signals. This technique can readily replace a number of analog locking systems advantageously in a variety of optical experiments.

  10. Microcontroller-based locking in optics experiments

    Energy Technology Data Exchange (ETDEWEB)

    Huang, K. [Laboratoire Kastler Brossel, UPMC-Sorbonne Universités, CNRS, ENS-PSL Research University, Collège de France, 4 place Jussieu, 75005 Paris (France); State Key Laboratory of Precision Spectroscopy, East China Normal University, Shanghai 200062 (China); Le Jeannic, H.; Ruaudel, J.; Morin, O.; Laurat, J., E-mail: julien.laurat@upmc.fr [Laboratoire Kastler Brossel, UPMC-Sorbonne Universités, CNRS, ENS-PSL Research University, Collège de France, 4 place Jussieu, 75005 Paris (France)

    2014-12-15

    Optics experiments critically require the stable and accurate locking of relative phases between light beams or the stabilization of Fabry-Perot cavity lengths. Here, we present a simple and inexpensive technique based on a stand-alone microcontroller unit to perform such tasks. Easily programmed in C language, this reconfigurable digital locking system also enables automatic relocking and sequential functioning. Different algorithms are detailed and applied to fringe locking and to low- and high-finesse optical cavity stabilization, without the need of external modulations or error signals. This technique can readily replace a number of analog locking systems advantageously in a variety of optical experiments.

  11. Instantaneous power control of a high speed permanent magnet synchronous generator based on a sliding mode observer and a phase locked loop

    Science.gov (United States)

    Duan, Jiandong; Fan, Shaogui; Wu, Fengjiang; Sun, Li; Wang, Guanglin

    2018-06-01

    This paper proposes an instantaneous power control method for high speed permanent magnet synchronous generators (PMSG), to realize the decoupled control of active power and reactive power, through vector control based on a sliding mode observer (SMO), and a phase locked loop (PLL). Consequently, the high speed PMSG has a high internal power factor, to ensure efficient operation. Vector control and accurate estimation of the instantaneous power require an accurate estimate of the rotor position. The SMO is able to estimate the back electromotive force (EMF). The rotor position and speed can be obtained using a combination of the PLL technique and the phase compensation method. This method has the advantages of robust operation, and being resistant to noise when estimating the position of the rotor. Using instantaneous power theory, the relationship between the output active power, reactive power, and stator current of the PMSG is deduced, and the power constraint condition is analysed for operation at the unit internal power factor. Finally, the accuracy of the rotor position detection, the instantaneous power detection, and the control methods are verified using simulations and experiments.

  12. A 65nm CMOS low-power MedRadio-band integer-N cascaded phase-locked loop for implantable medical systems.

    Science.gov (United States)

    Wang, Yi-Xiao; Chen, Wei-Ming; Wu, Chung-Yu

    2014-01-01

    This paper presents a low-power MedRadio-band integer-N phase-locked Loop (PLL) system which is composed of two charge-pump PLLs cascade connected. The PLL provides the operation clock and local carrier signals for an implantable medical electronic system. In addition, to avoid the off-chip crystal oscillator, the 13.56 MHz Industrial, Scientific and Medical (ISM) band signal from the wireless power transmission system is adopted as the input reference signal for the PLL. Ring-based voltage controlled oscillators (VCOs) with current control units are adopted to reduce chip area and power dissipation. The proposed cascaded PLL system is designed and implemented in TSMC 65-nm CMOS technology. The measured jitter for 216.96 MHz signal is 12.23 ps and the phase noise is -65.9 dBc/Hz at 100 kHz frequency offset under 402.926 MHz carrier frequency. The measured power dissipations are 66 μW in the first PLL and 195 μW in the whole system under 1-V supply voltage. The chip area is 0.1088 mm(2) and no off-chip component is required which is suitable for the integration of the implantable medical electronic system.

  13. Phase Noise and Intensity Noise of the Pulse Train Generated from Mode-locked Lasers in the Demodulation Measurement

    OpenAIRE

    Wu, Kan; Shum, Ping

    2010-01-01

    The phase noise and intensity noise of a pulse train are theoretically analyzed in the demodulation measurement. The effect of pulse asymmetry is discussed for the first time using Fourier series. Experimentally, photodetectors with different bandwidth and incident power levels are compared to achieve minimum pulse distortion.

  14. Electron self-injection and trapping into an evolving plasma bubble.

    Science.gov (United States)

    Kalmykov, S; Yi, S A; Khudik, V; Shvets, G

    2009-09-25

    The blowout (or bubble) regime of laser wakefield acceleration is promising for generating monochromatic high-energy electron beams out of low-density plasmas. It is shown analytically and by particle-in-cell simulations that self-injection of the background plasma electrons into the quasistatic plasma bubble can be caused by slow temporal expansion of the bubble. Sufficient criteria for the electron trapping and bubble's expansion rate are derived using a semianalytic nonstationary Hamiltonian theory. It is further shown that the combination of bubble's expansion and contraction results in monoenergetic electron beams.

  15. Versatile high-repetition-rate phase-locked chopper system for fast timing experiments in the vacuum ultraviolet and x-ray spectral region

    Energy Technology Data Exchange (ETDEWEB)

    Plogmaker, Stefan; Johansson, Erik M. J.; Rensmo, Haakan; Feifel, Raimund; Siegbahn, Hans [Department of Physics and Astronomy, Uppsala University, Box 516, SE-751 20 Uppsala (Sweden); Linusson, Per [Department of Physics, Stockholm University, AlbaNova University Center, SE-106 91 Stockholm (Sweden); Eland, John H. D. [Department of Physics and Astronomy, Uppsala University, Box 516, SE-751 20 Uppsala (Sweden); Department of Chemistry, Physical and Theoretical Chemistry Laboratory, Oxford University, South Parks Road, Oxford OX1 3QZ (United Kingdom); Baker, Neville [Department of Chemistry, Physical and Theoretical Chemistry Laboratory, Oxford University, South Parks Road, Oxford OX1 3QZ (United Kingdom)

    2012-01-15

    A novel light chopper system for fast timing experiments in the vacuum-ultraviolet (VUV) and x-ray spectral region has been developed. It can be phase-locked and synchronized with a synchrotron radiation storage ring, accommodating repetition rates in the range of {approx}8 to {approx}120 kHz by choosing different sets of apertures and subharmonics of the ring frequency (MHz range). Also the opening time of the system can be varied from some nanoseconds to several microseconds to meet the needs of a broad range of applications. Adjusting these parameters, the device can be used either for the generation of single light pulses or pulse packages from a microwave driven, continuous He gas discharge lamp or from storage rings which are otherwise often considered as quasi-continuous light sources. This chopper can be utilized for many different kinds of experiments enabling, for example, unambiguous time-of-flight (TOF) multi-electron coincidence studies of atoms and molecules excited by a single light pulse as well as time-resolved visible laser pump x-ray probe electron spectroscopy of condensed matter in the valence and core level region.

  16. Long-term clinical evaluation of the automatic stance-phase lock-controlled prosthetic knee joint in young adults with unilateral above-knee amputation.

    Science.gov (United States)

    Andrysek, Jan; Wright, F Virginia; Rotter, Karin; Garcia, Daniela; Valdebenito, Rebeca; Mitchell, Carlos Alvarez; Rozbaczylo, Claudio; Cubillos, Rafael

    2017-05-01

    The purpose of this study was to clinically evaluate the automatic stance-phase lock (ASPL) knee mechanism against participants' existing weight-activated braking (WAB) prosthetic knee joint. This prospective crossover study involved 10 young adults with an above-knee amputation. Primary measurements consisted of tests of walking speeds and capacity. Heart rate was measured during the six-minute walk test and the Physiological Cost Index (PCI) which was calculated from heart rate estimated energy expenditure. Activity was measured with a pedometer. User function and quality of life were assessed using the Lower Limb Function Questionnaire (LLFQ) and Prosthetic Evaluation Questionnaire (PEQ). Long-term follow-up over 12 months were completed. Walking speeds were the same for WAB and APSL knees. Energy expenditure (PCI) was lower for the ASPL knees (p = 0.007). Step counts were the same for both knees, and questionnaires indicated ASPL knee preference attributed primarily to knee stability and improved walking, while limitations included terminal impact noise. Nine of 10 participants chose to keep using the ASPL knee as part of the long-term follow-up. Potential benefits of the ASPL knee were identified in this study by functional measures, questionnaires and user feedback, but not changes in activity or the PEQ.

  17. Phase locking of a 1.5 Terahertz quantum cascade laser and use as a local oscillator in a heterodyne HEB receiver.

    Science.gov (United States)

    Rabanus, D; Graf, U U; Philipp, M; Ricken, O; Stutzki, J; Vowinkel, B; Wiedner, M C; Walther, C; Fischer, M; Faist, J

    2009-02-02

    We demonstrate for the first time the closure of an electronic phase lock loop for a continuous-wave quantum cascade laser (QCL) at 1.5 THz. The QCL is operated in a closed cycle cryo cooler. We achieved a frequency stability of better than 100 Hz, limited by the resolution bandwidth of the spectrum analyser. The PLL electronics make use of the intermediate frequency (IF) obtained from a hot electron bolometer (HEB) which is downconverted to a PLL IF of 125 MHz. The coarse selection of the longitudinal mode and the fine tuning is achieved via the bias voltage of the QCL. Within a QCL cavity mode, the free-running QCL shows frequency fluctuations of about 5 MHz, which the PLL circuit is able to control via the Stark-shift of the QCL gain material. Temperature dependent tuning is shown to be nonlinear, and of the order of -16 MHz/K. Additionally we have used the QCL as local oscillator (LO) to pump an HEB and perform, again for the first time at 1.5 THz, a heterodyne experiment, and obtain a receiver noise temperature of 1741 K.

  18. Analyzing the propagation behavior of coherence and polarization degrees of a phase-locked partially coherent radial flat-topped array laser beam in underwater turbulence.

    Science.gov (United States)

    Kashani, Fatemeh Dabbagh; Yousefi, Masoud

    2016-08-10

    In this research, based on an analytical expression for cross-spectral density (CSD) matrix elements, coherence and polarization properties of phase-locked partially coherent flat-topped (PCFT) radial array laser beams propagating through weak oceanic turbulence are analyzed. Spectral degrees of coherence and polarization are analytically calculated using CSD matrix elements. Also, the effective width of spatial degree of coherence (EWSDC) is calculated numerically. The simulation is done by considering the effects of source parameters (such as radius of the array setup's circle, effective width of the spectral degree of coherence, and wavelength) and turbulent ocean factors (such as the rate of dissipation of the turbulent kinetic energy per unit mass of fluid and relative strength of temperature and salinity fluctuations, Kolmogorov micro-scale, and rate of dissipation of the mean squared temperature) in detail. Results indicate that any change in the amount of turbulence factors that increase the turbulence power reduces the EWSDC significantly and causes the reduction in the degree of polarization, and occurs at shorter propagation distances but with smaller magnitudes. In addition, being valid for all conditions, the degradation rate of the EWSDC of Gaussian array beams are more in comparison with the PCFT ones. The simulation and calculation results are shown by graphs.

  19. Direct phase-locking of a 8.6-μm quantum cascade laser to a mid-IR optical frequency comb: application to precision spectroscopy of N2O.

    Science.gov (United States)

    Gambetta, Alessio; Cassinerio, Marco; Coluccelli, Nicola; Fasci, Eugenio; Castrillo, Antonio; Gianfrani, Livio; Gatti, Davide; Marangoni, Marco; Laporta, Paolo; Galzerano, Gianluca

    2015-02-01

    We developed a high-precision spectroscopic system at 8.6 μm based on direct heterodyne detection and phase-locking of a room-temperature quantum-cascade-laser against an harmonic, 250-MHz mid-IR frequency comb obtained by difference-frequency generation. The ∼30  dB signal-to-noise ratio of the detected beat-note together with the achieved closed-loop locking bandwidth of ∼500  kHz allows for a residual integrated phase noise of 0.78 rad (1 Hz-5 MHz), for an ultimate resolution of ∼21  kHz, limited by the measured linewidth of the mid-IR comb. The system was used to perform absolute measurement of line-center frequencies for the rotational components of the ν2 vibrational band of N2O, with a relative precision of 3×10(-10).

  20. Neural Correlates of Task Cost for Stance Control with an Additional Motor Task: Phase-Locked Electroencephalogram Responses

    Science.gov (United States)

    Hwang, Ing-Shiou; Huang, Cheng-Ya

    2016-01-01

    With appropriate reallocation of central resources, the ability to maintain an erect posture is not necessarily degraded by a concurrent motor task. This study investigated the neural control of a particular postural-suprapostural procedure involving brain mechanisms to solve crosstalk between posture and motor subtasks. Participants completed a single posture task and a dual-task while concurrently conducting force-matching and maintaining a tilted stabilometer stance at a target angle. Stabilometer movements and event-related potentials (ERPs) were recorded. The added force-matching task increased the irregularity of postural response rather than the size of postural response prior to force-matching. In addition, the added force-matching task during stabilometer stance led to marked topographic ERP modulation, with greater P2 positivity in the frontal and sensorimotor-parietal areas of the N1-P2 transitional phase and in the sensorimotor-parietal area of the late P2 phase. The time-frequency distribution of the ERP primary principal component revealed that the dual-task condition manifested more pronounced delta (1–4 Hz) and beta (13–35 Hz) synchronizations but suppressed theta activity (4–8 Hz) before force-matching. The dual-task condition also manifested coherent fronto-parietal delta activity in the P2 period. In addition to a decrease in postural regularity, this study reveals spatio-temporal and temporal-spectral reorganizations of ERPs in the fronto-sensorimotor-parietal network due to the added suprapostural motor task. For a particular set of postural-suprapostural task, the behavior and neural data suggest a facilitatory role of autonomous postural response and central resource expansion with increasing interregional interactions for task-shift and planning the motor-suprapostural task. PMID:27010634

  1. Wall locking and multiple nonlinear states of magnetic islands

    International Nuclear Information System (INIS)

    Persson, Mikael; Australian National Univ., Canberra, ACT

    1994-01-01

    The nonlinear evolution of magnetic islands is analysed in configurations with multiple resonant magnetic surfaces. The existence of multiple nonlinear steady states, is discussed. These are shown to be associated with states where the dynamics around the different rational surfaces are coupled or decoupled and in the presence of a wall of finite resistivity may correspond wall-locked or non-wall-locked magnetic islands. For the case of strong wall stabilization the locking is shown to consist of two different phases. During the first phase the locking of the plasma at the different rational surfaces occurs. Only when the outermost resonant magnetic surface has locked to the inner surfaces can the actual wall locking process take place. Consequently, wall locking, of a global mode, involving more than one rational surface, can be prevented by the decoupling of the resonant magnetic surfaces by plasma rotation. Possible implications on tokamak experiments are discussed. (author)

  2. Evaluation of a pulsed phase-locked loop system for noninvasive tracking of bone deformation under loading with finite element and strain analysis

    International Nuclear Information System (INIS)

    Serra-Hsu, Frederick; Cheng, Jiqi; Qin, Yi-Xian; Lynch, Ted

    2011-01-01

    Ultrasound has been widely used to nondestructively evaluate various materials, including biological tissues. Quantitative ultrasound has been used to assess bone quality and fracture risk. A pulsed phase-locked loop (PPLL) method has been proven for very sensitive tracking of ultrasound time-of-flight (TOF) changes. The objective of this work was to determine if the PPLL TOF tracking is sensitive to bone deformation changes during loading. The ability to noninvasively detect bone deformations has many implications, including assessment of bone strength and more accurate osteoporosis diagnostics and fracture risk prediction using a measure of bone mechanical quality. Fresh sheep femur cortical bone shell samples were instrumented with three 3-element rosette strain gauges and then tested under mechanical compression with eight loading levels using an MTS machine. Samples were divided into two groups based on internal marrow cavity content: with original marrow, or replaced with water. During compressive loading ultrasound waves were measured through acoustic transmission across the mid-diaphysis of bone. Finite element analysis (FEA) was used to describe ultrasound propagation path length changes under loading based on µCT-determined bone geometry. The results indicated that PPLL output correlates well to measured axial strain, with R 2 values of 0.70 ± 0.27 and 0.62 ± 0.29 for the marrow and water groups, respectively. The PPLL output correlates better with the ultrasound path length changes extracted from FEA. For the two validated FEA tests, correlation was improved to R 2 = 0.993 and R 2 = 0.879 through cortical path, from 0.815 and 0.794 via marrow path, respectively. This study shows that PPLL readings are sensitive to displacement changes during external bone loading, which may have potential to noninvasively assess bone strain and tissue mechanical properties

  3. Distinction between perceptual and attentional processing in working memory tasks: a study of phase-locked and induced oscillatory brain dynamics.

    Science.gov (United States)

    Deiber, Marie-Pierre; Missonnier, Pascal; Bertrand, Olivier; Gold, Gabriel; Fazio-Costa, Lara; Ibañez, Vicente; Giannakopoulos, Panteleimon

    2007-01-01

    Working memory involves the short-term storage and manipulation of information necessary for cognitive performance, including comprehension, learning, reasoning and planning. Although electroencephalogram (EEG) rhythms are modulated during working memory, the temporal relationship of EEG oscillations with the eliciting event has not been well studied. In particular, the dynamics of the neural network supporting memory processes may be best captured in induced oscillations, characterized by a loose temporal link with the stimulus. In order to differentiate induced from evoked functional processes, the present study proposes a time-frequency analysis of the 3 to 30 Hz EEG oscillatory activity in a verbal n-back working memory paradigm. Control tasks were designed to identify oscillatory activity related to stimulus presentation (passive task) and focused attention to the stimulus (detection task). Evoked theta activity (4-8 Hz) phase-locked to the visual stimulus was evidenced in the parieto-occipital region for all tasks. In parallel, induced theta activity was recorded in the frontal region for detection and n-back memory tasks, but not for the passive task, suggesting its dependency on focused attention to the stimulus. Sustained induced oscillatory activity was identified in relation to working memory in the theta and beta (15-25 Hz) frequency bands, larger for the highest memory load. Its late occurrence limited to nonmatched items suggests that it could be related to item retention and active maintenance for further task requirements. Induced theta and beta activities displayed respectively a frontal and parietal topographical distribution, providing further functional information on the fronto-posterior network supporting working memory.

  4. Locked modes and magnetic field errors in MST

    International Nuclear Information System (INIS)

    Almagri, A.F.; Assadi, S.; Prager, S.C.; Sarff, J.S.; Kerst, D.W.

    1992-06-01

    In the MST reversed field pinch magnetic oscillations become stationary (locked) in the lab frame as a result of a process involving interactions between the modes, sawteeth, and field errors. Several helical modes become phase locked to each other to form a rotating localized disturbance, the disturbance locks to an impulsive field error generated at a sawtooth crash, the error fields grow monotonically after locking (perhaps due to an unstable interaction between the modes and field error), and over the tens of milliseconds of growth confinement degrades and the discharge eventually terminates. Field error control has been partially successful in eliminating locking

  5. Production of a monoenergetic electron bunch in a self-injected laser-wakefield accelerator

    International Nuclear Information System (INIS)

    Chang, C.-L.; Hsieh, C.-T.; Ho, Y.-C.; Chen, Y.-S.; Lin, J.-Y.; Wang, J.; Chen, S.-Y.

    2007-01-01

    Production of a monoenergetic electron bunch in a self-injected laser-wakefield accelerator is investigated with a tomographic method which resolves the electron injection and acceleration processes. It is found that all the electrons in the monoenergetic electron bunch are injected at the same location in the plasma column and then accelerated with an acceleration gradient exceeding 2 GeV/cm. The injection position shifts with the position of pump-pulse focus, and no significant deceleration is observed for the monoenergetic electron bunch after it reaches the maximum energy. The results are consistent with the model of transverse wave breaking and beam loading for the injection of monoenergetic electrons. The tomographic method adds a crucial dimension to the whole array of existing diagnostics for laser beams, plasma waves, and electron beams. With this method the details of the underlying physical processes in laser-plasma interactions can be resolved and compared directly to particle-in-cell simulations

  6. Optical double-locked semiconductor lasers

    Science.gov (United States)

    AlMulla, Mohammad

    2018-06-01

    Self-sustained period-one (P1) nonlinear dynamics of a semiconductor laser are investigated when both optical injection and modulation are applied for stable microwave frequency generation. Locking the P1 oscillation through modulation on the bias current, injection strength, or detuning frequency stabilizes the P1 oscillation. Through the phase noise variance, the different modulation types are compared. It is demonstrated that locking the P1 oscillation through optical modulation on the output of the master laser outperforms bias-current modulation of the slave laser. Master laser modulation shows wider P1-oscillation locking range and lower phase noise variance. The locking characteristics of the P1 oscillation also depend on the operating conditions of the optical injection system

  7. High-precision broad-band linear polarimetry of early-type binaries. II. Variable, phase-locked polarization in triple Algol-type system λ Tauri

    Science.gov (United States)

    Berdyugin, A.; Piirola, V.; Sakanoi, T.; Kagitani, M.; Yoneda, M.

    2018-03-01

    Aim. To study the binary geometry of the classic Algol-type triple system λ Tau, we have searched for polarization variations over the orbital cycle of the inner semi-detached binary, arising from light scattering in the circumstellar material formed from ongoing mass transfer. Phase-locked polarization curves provide an independent estimate for the inclination i, orientation Ω, and the direction of the rotation for the inner orbit. Methods: Linear polarization measurements of λ Tau in the B, V , and R passbands with the high-precision Dipol-2 polarimeter have been carried out. The data have been obtained on the 60 cm KVA (Observatory Roque de los Muchachos, La Palma, Spain) and Tohoku 60 cm (Haleakala, Hawaii, USA) remotely controlled telescopes over 69 observing nights. Analytic and numerical modelling codes are used to interpret the data. Results: Optical polarimetry revealed small intrinsic polarization in λ Tau with 0.05% peak-to-peak variation over the orbital period of 3.95 d. The variability pattern is typical for binary systems showing strong second harmonic of the orbital period. We apply a standard analytical method and our own light scattering models to derive parameters of the inner binary orbit from the fit to the observed variability of the normalized Stokes parameters. From the analytical method, the average for three passband values of orbit inclination i = 76° + 1°/-2° and orientation Ω = 15°(195°) ± 2° are obtained. Scattering models give similar inclination values i = 72-76° and orbit orientation ranging from Ω = 16°(196°) to Ω = 19°(199°), depending on the geometry of the scattering cloud. The rotation of the inner system, as seen on the plane of the sky, is clockwise. We have found that with the scattering model the best fit is obtained for the scattering cloud located between the primary and the secondary, near the inner Lagrangian point or along the Roche lobe surface of the secondary facing the primary. The inclination i

  8. Effect of re-coaching on self-injection of insulin in older diabetic patients - Impact of cognitive impairment.

    Science.gov (United States)

    Omori, Keiko; Kawamura, Takahiko; Urata, Misako; Matsuura, Mayumi; Kusama, Minoru; Imamine, Rui; Watarai, Atsuko; Nakashima, Eitaro; Umemura, Toshitaka; Hotta, Nigishi

    2017-08-01

    We investigated the effect of re-coaching on self-injection of insulin and impact of cognitive function in 100 older diabetic patients. We examined patients on a variety of skills and knowledge regarding self-injection of insulin and evaluated the effect of re-coaching the patients after 3months and 4years. We also investigated the influence of cognitive impairment (CI) on coaching. Skills scores for self-injection of insulin and HbA1c improved significantly 3months after re-coaching. In 51 patients followed-up for 4years, skills scores were maintained during the 4years, while knowledge scores improved after 3months but then returned to the baseline level. In the group of patients with CI as determined by the Mini-Mental Status Examination, skills scores were similar to those in the group without CI, while knowledge scores were significantly lower as compared with those in the group without CI at any time point. Skills scores were maintained during the 4years regardless of CI. The present study showed that re-coaching in skills for self-injection of insulin was effective in improving and maintaining insulin treatment in older diabetic patients, even if patients had CI. Copyright © 2017 Elsevier B.V. All rights reserved.

  9. Phobia of self-injecting and self-testing in insulin-treated diabetes patients: opportunities for screening

    NARCIS (Netherlands)

    Mollema, E. D.; Snoek, F. J.; Heine, R. J.; van der Ploeg, H. M.

    2001-01-01

    To define clinically relevant cut-off points for severe fear of self-injecting (FSI) and self-testing (FST) (phobia) in insulin-treated patients with diabetes, and to estimate the magnitude of these phobias in our research population. FSI and FST were assessed in a cross-sectional survey using the

  10. Patient assessment of an electronic device for subcutaneous self-injection of interferon ß-1a for multiple sclerosis: an observational study in the UK and Ireland

    Directory of Open Access Journals (Sweden)

    D'Arcy C

    2012-01-01

    Full Text Available Caroline D’Arcy1, Del Thomas2, Dee Stoneman3, Laura Parkes31West London Neuroscience Centre, Charing Cross Hospital, London, UK; 2Wye Valley NHS Trust, Hereford, UK; 3Merck Serono Ltd, Feltham, Middlesex, UKBackground: Injectable disease-modifying drugs (DMDs reduce the number of relapses and delay disability progression in patients with relapsing–remitting multiple sclerosis (RRMS. Regular self-injection can be stressful and impeded by MS symptoms. Auto-injection devices can simplify self-injection, overcome injection-related issues, and increase treatment satisfaction. This study investigated patient responses to an electronic auto-injection device.Methods: Patients with RRMS (n = 63, aged 18–65 years, naïve to subcutaneous (sc interferon (IFN ß-1a therapy, were recruited to a Phase IV, observational, open-label, multicenter study (NCT01195870. Patients self-injected sc IFN ß-1a using the RebiSmart™ (Merck Serono S.A. – Geneva, Switzerland electronic auto-injector for 12 weeks, including an initial titration period if recommended by the prescribing physician. In week 12, patients completed a questionnaire comprising of a visual analog scale (VAS to rate how much they liked using the device, a four-point response question on ease of use (‘very difficult’, ‘difficult’, ‘easy’, or ‘very easy’, and a list of ten device functions to rank, based upon their experiences.Results: Six patients (9.5% discontinued the study: one switched to manual injection; two discontinued all treatment; three changed therapy. In total, 59 out of 63 patients (93.7% completed the VAS; 54 out of 59 (91.5%; 95% confidence interval: 81.3%–97.2% ‘liked’ using the electronic auto-injector (score ≥6, whereas 57 out of 59 (96.6% rated the device overall as ‘easy’ or ‘very easy’ to use. Device features rated as most useful were the hidden needle (mean [standard deviation] score: 3.3 [3.01]; n = 56, confirmation sound (3.9 [2.45], and

  11. Protective air lock

    International Nuclear Information System (INIS)

    Evans, H.W.

    1976-01-01

    A device suitable for preventing escape and subsequent circulation of toxic gases is described. An enclosure is sealed by a surrounding air lock, and an automatic mechanism partially evacuates the enclosure and air lock. The enclosure ventilating mechanism can be disconnected so that a relatively undisturbed atmosphere is created in the enclosure

  12. Bicycle Parking and Locking

    DEFF Research Database (Denmark)

    Larsen, Jonas

    2017-01-01

    . This article contributes with new insights into parking and locking - ‘moorings’ - to cycling literature. It presents an ethnography of ‘design moorings’ and practices associated with parking and locking bikes. The main case study is the very pro-cycling city of Copenhagen. Yet to explore what is unique about...

  13. Analysis of peer-to-peer locking of magnetrons

    International Nuclear Information System (INIS)

    Pengvanich, P.; Lau, Y. Y.; Cruz, E.; Gilgenbach, R. M.; Hoff, B.; Luginsland, J. W.

    2008-01-01

    The condition for mutual, or peer-to-peer, locking of two magnetrons is derived. This condition reduces to Adler's classical phase-locking condition in the limit where one magnetron becomes the ''master'' and the other becomes the ''slave.'' The formulation is extended to the peer-to-peer locking of N magnetrons, under the assumption that the electromagnetic coupling among the N magnetrons is modeled by an N-port network.

  14. Simple and robust phase-locking of optical cavities with > 200 KHz servo-bandwidth using a piezo-actuated mirror mounted in soft materials.

    Science.gov (United States)

    Goldovsky, David; Jouravsky, Valery; Pe'er, Avi

    2016-12-12

    We present an approach to locking of optical cavities with piezoelectric actuated mirrors based on a simple and effective mechanical decoupling of the mirror and actuator from the surrounding mount. Using simple elastic materials (e.g. rubber or soft silicone gel pads) as mechanical dampers between the piezo-mirror compound and the surrounding mount, a firm and stable mounting of a relatively large mirror (8mm diameter) can be maintained that is isolated from external mechanical resonances, and is limited only by the internal piezo-mirror resonance of > 330 KHz. Our piezo lock showed positive servo gain up to 208 KHz, and a temporal response to a step interference within < 3 μs.

  15. Surgical solutions for the complications of the Vaseline self-injection of the penis.

    Science.gov (United States)

    Bajory, Zoltán; Mohos, Gábor; Rosecker, Agnes; Bordás, Noémi; Pajor, László

    2013-04-01

    Penile girth enhancement by the injection of Vaseline is an existing practice. Many cases develop severe complications that need surgery. To report on the reconstructive surgical solutions of the complications of Vaseline self-injection and the outcomes. To develop a modification of a one-step reconstruction method involving the use of pedicled scrotal flaps. The complications and their surgical solutions were classified as regards severity and difficulty. The outcomes were observed and a newly introduced one-step surgical method was investigated. Seventy-eight consecutive patients (87.2% of them with a history of imprisonment) were divided into three groups. In group A, aesthetic penile defects or phimosis caused by the Vaseline necessitated circumcision or local excision. In group B, the whole penile skin was involved, and total skin removal and two- or (a newly modified) one-step reconstructive surgery were performed. In group C, both the whole penile skin and the scrotum were involved: complete skin removal and skin grafting or skin pedicled flap transplantation were carried out. In five cases in group B, postoperative skin necrosis made a second operation necessary. There was one intraoperative urethral injury, where a urethral fistula developed and a second urethral reconstruction was performed. There was no major complication with the newly developed one-stage pedicled flap procedure. At the end of the therapy, all the cases were healed. All of the patients reported successful sexual intercourse after the operations and 91% were satisfied with the result. The complications depend mainly on the amount of Vaseline injected, the hygienic circumstances, and the personal tolerability. In the worst cases, only radical skin removal and skin transplantation can solve the problem. The newly developed one-step arterial branch-preserving scrotal skin flap reconstruction appears to be a suitable and cost-effective solution for these patients. © 2013 International

  16. ''Old'' locked inflation

    International Nuclear Information System (INIS)

    Liu, Yang; Piao, Yun-Song; Si, Zong-Guo

    2009-01-01

    In this paper, we revisit the idea of locked inflation, which does not require a potential satisfying the normal slow-roll condition, but suffers from the problems associated with ''saddle inflation''. We propose a scenario based on locked inflation, however, with an alternative evolution mechanism of the ''waterfall field'' φ. Instead of rolling down along the potential, the φ field will tunnel to end the inflation stage like in old inflation, by which the saddle inflation could be avoided. Further, we study a cascade of old locked inflation, which can be motivated by the string landscape. Our model is based on the consideration of making locked inflation feasible so as to give a working model without slow roll; It also can be seen as an effort to embed the old inflation in string landscape

  17. LOCKS AND KEYS SERVICE

    CERN Multimedia

    Locks and Keys Service

    2002-01-01

    The Locks and Keys service (ST/FM) will move from building 55 to building 570 from the 2nd August to the 9th August 2002 included. During this period the service will be closed. Only in case of extreme urgency please call the 164550. Starting from Monday, 12th August, the Locks and Keys Service will continue to follow the activities related to office keys (keys and locks) and will provide the keys for furniture. The service is open from 8h30 to 12h00 and from 13h00 to 17h30. We remind you that your divisional correspondents can help you in the execution of the procedures. We thank you for your comprehension and we remain at your service to help you in solving all the matters related to keys for offices and furniture. Locks and Keys Service - ST Division - FM Group

  18. Desire for penile girth enhancement and the effects of the self-injection of hyaluronic acid gel

    Directory of Open Access Journals (Sweden)

    Enis Rauf Coskuner

    2012-01-01

    Full Text Available Penile girth enhancement is a controversial subject but demands for enhancement are increasing steadily. Although various fillers have been widely used for soft tissue augmentation, there is no reliable material for this particular situation. Here we report a case of an acute hypersensitivity reaction in a man after his first self-injection of a filler material, which, he claimed, was hyaluronic acid gel for penile girth enhancement and glans penis augmentation.

  19. Desire for penile girth enhancement and the effects of the self-injection of hyaluronic Acid gel.

    Science.gov (United States)

    Coskuner, Enis Rauf; Canter, Halil Ibrahim

    2012-07-01

    Penile girth enhancement is a controversial subject but demands for enhancement are increasing steadily. Although various fillers have been widely used for soft tissue augmentation, there is no reliable material for this particular situation. Here we report a case of an acute hypersensitivity reaction in a man after his first self-injection of a filler material, which, he claimed, was hyaluronic acid gel for penile girth enhancement and glans penis augmentation.

  20. Desire for Penile Girth Enhancement and the Effects of the Self-Injection of Hyaluronic Acid Gel

    OpenAIRE

    Coskuner, Enis Rauf; Canter, Halil Ibrahim

    2012-01-01

    Penile girth enhancement is a controversial subject but demands for enhancement are increasing steadily. Although various fillers have been widely used for soft tissue augmentation, there is no reliable material for this particular situation. Here we report a case of an acute hypersensitivity reaction in a man after his first self-injection of a filler material, which, he claimed, was hyaluronic acid gel for penile girth enhancement and glans penis augmentation.

  1. Locke and botany.

    Science.gov (United States)

    Anstey, Peter R; Harris, Stephen A

    2006-06-01

    This paper argues that the English philosopher John Locke, who has normally been thought to have had only an amateurish interest in botany, was far more involved in the botanical science of his day than has previously been known. Through the presentation of new evidence deriving from Locke's own herbarium, his manuscript notes, journal and correspondence, it is established that Locke made a modest contribution to early modern botany. It is shown that Locke had close and ongoing relations with the Bobarts, keepers of the Oxford Botanic Garden, and that Locke distributed seeds and plant parts to other botanists, seeds of which the progeny almost certainly ended up in the most important herbaria of the period. Furthermore, it is claimed that the depth of Locke's interest in and practice of botany has a direct bearing on our understanding of his views on the correct method of natural philosophy and on the interpretation of his well known discussion of the nature of species in Book III of his Essay concerning human understanding.

  2. Teaching methotrexate self-injection with a web-based video maintains patient care while reducing healthcare resources: a pilot study.

    Science.gov (United States)

    Katz, Steven J; Leung, Sylvia

    2015-01-01

    The aim of the study was to compare standard nurse-led methotrexate self-injection patient education to a web-based methotrexate self-injection education video in conjunction with standard teaching on patient self-confidence for self-injection, as well as patient satisfaction, patient knowledge and teaching time. Consecutive rheumatology patients seen for methotrexate self-injection education were enrolled. Prior to education, patient self-confidence for self-injection, age, gender and education were recorded. Patients were randomized 1:1 to standard teaching or the intervention: a 12-min methotrexate self-injection education video followed by further in-person nurse education. Patients recorded their post-education confidence for self-injection, satisfaction with the teaching process and answered four specific questions testing knowledge on methotrexate self-injection. The time spent providing direct education to the patient was recorded. Twenty-nine patients participated in this study: 15 had standard (C) teaching and 14 were in the intervention group (I). Average age, gender and education level were similar in both groups. Both groups were satisfied with the quality of teaching. There was no difference in pre-confidence (C = 5.5/10 vs. I = 4.7/10, p = 0.44) or post-confidence (C = 8.8, I = 8.8, p = 0.93) between the groups. There was a trend toward improved patient knowledge in the video group versus the standard group (C = 4.7/6, I = 5.5/6, p = 0.15). Nurse teaching time was less in the video group (C = 60 min, I = 44 min, p = 0.012), with men requiring longer education time than women across all groups. An education video may be a good supplement to standard in-person nurse teaching for methotrexate self-injection. It equals the standard teaching practise with regard to patient satisfaction, confidence and knowledge while decreasing teaching time by 25 %.

  3. Pressure locking test results

    Energy Technology Data Exchange (ETDEWEB)

    DeWall, K.G.; Watkins, J.C.; McKellar, M.G.; Bramwell, D. [Idaho National Engineering Lab., Idaho Falls, ID (United States)] [and others

    1996-12-01

    The U.S. Nuclear Regulatory Commission (NRC), Office of Nuclear Regulatory Research, is funding the Idaho National Engineering Laboratory (INEL) in performing research to provide technical input for their use in evaluating responses to Generic Letter 95-07, {open_quotes}Pressure Locking and Thermal Binding of Safety-Related Power-Operated Gate Valves.{close_quotes} Pressure locking and thermal binding are phenomena that make a closed gate valve difficult to open. This paper discusses only the pressure locking phenomenon in a flexible-wedge gate valve; the authors will publish the results of their thermal binding research at a later date. Pressure locking can occur when operating sequences or temperature changes cause the pressure of the fluid in the bonnet (and, in most valves, between the discs) to be higher than the pressure on the upstream and downstream sides of the disc assembly. This high fluid pressure presses the discs against both seats, making the disc assembly harder to unseat than anticipated by the typical design calculations, which generally consider friction at only one of the two disc/seat interfaces. The high pressure of the bonnet fluid also changes the pressure distribution around the disc in a way that can further contribute to the unseating load. If the combined loads associated with pressure locking are very high, the actuator might not have the capacity to open the valve. The results of the NRC/INEL research discussed in this paper show that the relationship between bonnet pressure and pressure locking stem loads appears linear. The results also show that for this valve, seat leakage affects the bonnet pressurization rate when the valve is subjected to thermally induced pressure locking conditions.

  4. Pressure locking test results

    International Nuclear Information System (INIS)

    DeWall, K.G.; Watkins, J.C.; McKellar, M.G.; Bramwell, D.

    1996-01-01

    The U.S. Nuclear Regulatory Commission (NRC), Office of Nuclear Regulatory Research, is funding the Idaho National Engineering Laboratory (INEL) in performing research to provide technical input for their use in evaluating responses to Generic Letter 95-07, open-quotes Pressure Locking and Thermal Binding of Safety-Related Power-Operated Gate Valves.close quotes Pressure locking and thermal binding are phenomena that make a closed gate valve difficult to open. This paper discusses only the pressure locking phenomenon in a flexible-wedge gate valve; we will publish the results of our thermal binding research at a later date. Pressure locking can occur when operating sequences or temperature changes cause the pressure of the fluid in the bonnet (and, in most valves, between the discs) to be higher than the pressure on the upstream and downstream sides of the disc assembly. This high fluid pressure presses the discs against both seats, making the disc assembly harder to unseat than anticipated by the typical design calculations, which generally consider friction at only one of the two disc/seat interfaces. The high pressure of the bonnet fluid also changes the pressure distribution around the disc in a way that can further contribute to the unseating load. If the combined loads associated with pressure locking are very high, the actuator might not have the capacity to open the valve. The results of the NRC/INEL research discussed in this paper show that the relationship between bonnet pressure and pressure locking stem loads appears linear. The results also show that for this valve, seat leakage affects the bonnet pressurization rate when the valve is subjected to thermally induced pressure locking conditions

  5. High-Order Frequency-Locked Loops

    DEFF Research Database (Denmark)

    Golestan, Saeed; Guerrero, Josep M.; Quintero, Juan Carlos Vasquez

    2017-01-01

    In very recent years, some attempts for designing high-order frequency-locked loops (FLLs) have been made. Nevertheless, the advantages and disadvantages of these structures, particularly in comparison with a standard FLL and high-order phase-locked loops (PLLs), are rather unclear. This lack...... study, and its small-signal modeling, stability analysis, and parameter tuning are presented. Finally, to gain insight about advantages and disadvantages of high-order FLLs, a theoretical and experimental performance comparison between the designed second-order FLL and a standard FLL (first-order FLL...

  6. Mode locking of Yb:GdYAG ceramic lasers with an isotropic cavity

    International Nuclear Information System (INIS)

    Xu, C W; Tang, D Y; Zhu, H Y; Zhang, J

    2013-01-01

    We report on the passive mode locking of a diode pumped Yb:GdYAG ceramic laser with a near isotropic cavity. It is found that the laser could simultaneously mode lock in the two orthogonal principal polarization directions of the cavity, and the mode locked pulses of the two polarizations have identical features and are temporally perfectly synchronized. However, their pulse energy varies out-of-phase periodically, manifesting the antiphase dynamics of mode locked lasers. (letter)

  7. A scalable lock-free hash table with open addressing

    DEFF Research Database (Denmark)

    Nielsen, Jesper Puge; Karlsson, Sven

    2016-01-01

    and concurrent operations without any locks. In this paper, we present a new fully lock-free open addressed hash table with a simpler design than prior published work. We split hash table insertions into two atomic phases: first inserting a value ignoring other concurrent operations, then in the second phase......Concurrent data structures synchronized with locks do not scale well with the number of threads. As more scalable alternatives, concurrent data structures and algorithms based on widely available, however advanced, atomic operations have been proposed. These data structures allow for correct...

  8. Testing ultrafast mode-locking at microhertz relative optical linewidth.

    Science.gov (United States)

    Martin, Michael J; Foreman, Seth M; Schibli, T R; Ye, Jun

    2009-01-19

    We report new limits on the phase coherence of the ultrafast mode-locking process in an octave-spanning Ti:sapphire comb.We find that the mode-locking mechanism correlates optical phase across a full optical octave with less than 2.5 microHZ relative linewidth. This result is at least two orders of magnitude below recent predictions for quantum-limited individual comb-mode linewidths, verifying that the mode-locking mechanism strongly correlates quantum noise across the comb spectrum.

  9. Testing ultrafast mode-locking at microhertz relative optical linewidth

    OpenAIRE

    Martin, Michael J.; Foreman, Seth M.; Schibli, T. R.; Ye, Jun

    2008-01-01

    We report new limits on the phase coherence of the ultrafast mode-locking process in an octave-spanning Ti:sapphire comb. We find that the mode-locking mechanism correlates optical phase across a full optical octave with less than 2.5 micro Hz relative linewidth. This result is at least two orders of magnitude below recent predictions for quantum-limited individual comb-mode linewidths, verifying that the mode-locking mechanism strongly correlates quantum noise across the comb spectrum.

  10. Positioning and locking apparatus

    Science.gov (United States)

    Hayward, M.L.; Harper, W.H.

    1985-06-19

    A positioning and locking apparatus including a fixture having a rotatable torque ring provided with a plurality of cam segments for automatically guiding a container into a desired location within the fixture. Rotation of the ring turns the container into a final position in pressure sealing relation against a hatch member.

  11. Locked nucleic acid

    DEFF Research Database (Denmark)

    Jepsen, Jan Stenvang; Sørensen, Mads D; Wengel, Jesper

    2004-01-01

    Locked nucleic acid (LNA) is a class of nucleic acid analogs possessing very high affinity and excellent specificity toward complementary DNA and RNA, and LNA oligonucleotides have been applied as antisense molecules both in vitro and in vivo. In this review, we briefly describe the basic...

  12. Roller Locking Brake

    Science.gov (United States)

    Vranish, John M.

    1993-01-01

    Roller locking brake is normally braking rotary mechanism allowing free rotation when electromagnet in mechanism energized. Well suited to robots and other machinery which automatic braking upon removal of electrical power required. More compact and reliable. Requires little electrical power to maintain free rotation and exhibits minimal buildup of heat.

  13. Locks and Keys Service

    CERN Multimedia

    Claude Ducastel

    The GS-LS-SEM section is pleased to inform you that as from Monday 30 November 2009, the opening hours of the Locks and Keys service will be the following: 08h30 - 12h30 / 13h30 - 16:30, Mondays to Fridays. GS-SEM-LS 73333

  14. Tailoring the laser pulse shape to improve the quality of the self-injected electron beam in laser wakefield acceleration

    International Nuclear Information System (INIS)

    Upadhyay, Ajay K.; Samant, Sushil A.; Krishnagopal, S.

    2013-01-01

    In laser wakefield acceleration, tailoring the shape of the laser pulse is one way of influencing the laser-plasma interaction and, therefore, of improving the quality of the self-injected electron beam in the bubble regime. Using three-dimensional particle-in-cell simulations, the evolution dynamics of the laser pulse and the quality of the self-injected beam, for a Gaussian pulse, a positive skew pulse (i.e., one with sharp rise and slow fall), and a negative skew pulse (i.e., one with a slow rise and sharp fall) are studied. It is observed that with a negative skew laser pulse there is a substantial improvement in the emittance (by around a factor of two), and a modest improvement in the energy-spread, compared to Gaussian as well as positive skew pulses. However, the injected charge is less in the negative skew pulse compared to the other two. It is also found that there is an optimal propagation distance that gives the best beam quality; beyond this distance, though the energy increases, the beam quality deteriorates, but this deterioration is least for the negative skew pulse. Thus, the negative skew pulse gives an improvement in terms of beam quality (emittance and energy spread) over what one can get with a Gaussian or positive skew pulse. In part, this is because of the lesser injected charge, and the strong suppression of continuous injection for the negative skew pulse.

  15. Medico legal aspects of self-injection of metallic mercury in cases of suicide or self-harming.

    Science.gov (United States)

    Da Broi, Ugo; Moreschi, Carlo; Colatutto, Antonio; Marcon, Barbara; Zago, Silvia

    2017-08-01

    Metallic mercury may be self-injected for suicidal or self-harm purposes or sometimes for superstitious or other inadvisable reasons. Local tissue or systemic consequences such as mercurialism can frequently occur in cases of subcutaneous or deep injection, while death due to pulmonary embolism and cardiac, brain, hepatic or renal toxicity may occur in cases of high dosage intravenous administration. The aim of this review is to focus on the diagnostic difficulties facing coroners and forensic pathologists when the courts require confirmation that evidence of self-injection of metallic mercury is the result of suicide or self-harming. Forensic examination performed on the corpses of victims who died in or out of hospital or on surviving injured or intoxicated victims showing signs of mercurialism, demands the careful evaluation of the death scene, of all related circumstances and of the clinical and autopsy data. Close interaction between forensic pathologists and toxicologists is also needed to identify and quantify mercury levels in blood, urine and tissue. Copyright © 2017 Elsevier Ltd and Faculty of Forensic and Legal Medicine. All rights reserved.

  16. Investigation on Locking and Pulling Modes in Analog Frequency Dividers

    Directory of Open Access Journals (Sweden)

    Antonio Buonomo

    2013-01-01

    Full Text Available We compare the main analytical results available to estimate the locking range, which is the key figure-of-merit of LC frequency dividers based on the injection locking phenomenon. Starting from the classical result by Adler concerning injection-locked oscillators, we elucidate the merits and the shortcomings of the different approaches to study injection-locked frequency dividers, with particular emphasis on divider-by-2. In particular, we show the potential of a perturbation approach which enables a more complete analysis of frequency dividers, making it possible to calculate not only the amplitude and the phase of the locked oscillation, but also the region where it exists and is stable, which defines the locking region. Finally, we analyze the dynamical behaviour of the dividers in the vicinity of the boundary of the locking region, showing that there exists a border region where the occurrence of the locking or the pulling operation mode is possible, depending on the initial conditions of the system.

  17. Injection-locking of terahertz quantum cascade lasers up to 35GHz using RF amplitude modulation.

    Science.gov (United States)

    Gellie, Pierre; Barbieri, Stefano; Lampin, Jean-François; Filloux, Pascal; Manquest, Christophe; Sirtori, Carlo; Sagnes, Isabelle; Khanna, Suraj P; Linfield, Edmund H; Davies, A Giles; Beere, Harvey; Ritchie, David

    2010-09-27

    We demonstrate that the cavity resonance frequency - the round-trip frequency - of Terahertz quantum cascade lasers can be injection-locked by direct modulation of the bias current using an RF source. Metal-metal and single-plasmon waveguide devices with roundtrip frequencies up to 35GHz have been studied, and show locking ranges above 200MHz. Inside this locking range the laser round-trip frequency is phase-locked, with a phase noise determined by the RF-synthesizer. We find a square-root dependence of the locking range with RF-power in agreement with classical injection-locking theory. These results are discussed in the context of mode-locking operation.

  18. Innovation and Lock-in

    DEFF Research Database (Denmark)

    Cantner, Uwe; Vannuccini, Simone

    2016-01-01

    This study focuses on a well-known but yet elusive concept: (technological) lock-in. We summarize what is known about the nature of lock-in and offer a critical view on history-dependent processes based on recent contributions to the literature. We discuss if lock-ins are really inescapable......, especially when innovation is concerned. Also, we address the question if lock-in is a well-defined concept at all. To offer a fresh view on lock-in and to tackle the issues just raised, we employ the replicator dynamics model. By making a parallel between monopolization in the replicator dynamics...... and the occurrence of lock-ins, we show that the convergence of a system to a given outcome can be reversed, under certain conditions. We highlight the need for a more precise demarcation of the conceptual boundaries of lock-in and path dependence, both from the formal and the empirical side, and suggest...

  19. Injection locking of optomechanical oscillators via acoustic waves

    Science.gov (United States)

    Huang, Ke; Hossein-Zadeh, Mani

    2018-04-01

    Injection locking is a powerful technique for synchronization of oscillator networks and controlling the phase and frequency of individual oscillators using similar or other types of oscillators. Here, we present the first demonstration of injection locking of a radiation-pressure driven optomechanical oscillator (OMO) via acoustic waves. As opposed to previously reported techniques (based on pump modulation or direct application of a modulated electrostatic force), injection locking of OMO via acoustic waves does not require optical power modulation or physical contact with the OMO and it can easily be implemented on various platforms. Using this approach we have locked the phase and frequency of two distinct modes of a microtoroidal silica OMO to a piezoelectric transducer (PZT). We have characterized the behavior of the injection locked OMO with three acoustic excitation configurations and showed that even without proper acoustic impedance matching the OMO can be locked to the PZT and tuned over 17 kHz with only -30 dBm of RF power fed to the PZT. The high efficiency, simplicity and scalability of the proposed approach paves the road toward a new class of photonic systems that rely on synchronization of several OMOs to a single or multiple RF oscillators with applications in optical communication, metrology and sensing. Beyond its practical applications, injection locking via acoustic waves can be used in fundamental studies in quantum optomechanics where thermal and optical isolation of the OMO are critical.

  20. Towards a versatile active wavelength converter for all-optical networks based on quasi-phase matched intra-cavity difference-frequency generation.

    Science.gov (United States)

    Torregrosa, Adrián J; Maestre, Haroldo; Capmany, Juan

    2013-11-18

    The availability of reconfigurable all-optical wavelength converters for an efficient and flexible use of optical resources in WDM (wavelength division multiplexing) networks is still lacking at present. We propose and report preliminary results on a versatile active technique for multiple and tunable wavelength conversions in the 1500-1700 nm spectral region. The technique is based on combining broadband quasi-phase matched intra-cavity parametric single-pass difference-frequency generation close to degeneracy in a diode-pumped tunable laser. A periodically poled stoichiometric lithium tantalate crystal is used as the nonlinear medium, with a parametric pump wave generated in a continuous-wave self-injection locked Cr3+:LiCAF tunable laser operating at around 800 nm.

  1. Data port security lock

    Science.gov (United States)

    Quinby, Joseph D [Albuquerque, NM; Hall, Clarence S [Albuquerque, NM

    2008-06-24

    In a security apparatus for securing an electrical connector, a plug may be fitted for insertion into a connector receptacle compliant with a connector standard. The plug has at least one aperture adapted to engage at least one latch in the connector receptacle. An engagement member is adapted to partially extend through at least one aperture and lock to at least one structure within the connector receptacle.

  2. Squeezing in an injection-locked semiconductor laser

    Science.gov (United States)

    Inoue, S.; Machida, S.; Yamamoto, Y.; Ohzu, H.

    1993-09-01

    The intensity-noise properties of an injection-locked semiconductor laser were studied experimentally. The constant-current-driven semiconductor laser producing the amplitude-squeezed state whose intensity noise was reduced below the standard quantum limit (SQL) by 0.72 dB was injection-locked by an external master laser. The measured intensity-noise level of the injection-locked semiconductor laser was 0.91 dB below the SQL. This experimental result indicates that a phase-coherent amplitude-squeezed state or squeezed vacuum state together with a reference local oscillator wave can be generated directly by semiconductor laser systems.

  3. Locking of intrinsic angular momentum in collision complexes

    International Nuclear Information System (INIS)

    Berengolts, Alexander.

    1995-04-01

    A concept of locking of the intrinsic angular momentum of a fragment of a collision complex to a body-fixed axis is widely used in the description of heavy-particle dynamics. The aim of this work is to provide a semiclassical description of the locking phenomenon which occur in diatomic and three atomic collision complexes. The first part of this work is devoted to the semiclassical study of the locking of the electronic angular momentum that occurs in slow collisions of two atoms, one in the spherically symmetric state and the other in state with j= 1. Here we calculate explicitly the complete locking matrix for different types of interatomic interactions. The elements of this matrix directly enter into the semiclassical expression for the different cross sections of polarized atoms. Limitations to the notion of the the locking radius and slipping probability are discussed in connection with the steepness of the interaction. Numerical calculations confirm analytical result: the optimal criterion for determination of the locking radius is a condition for the accumulated phase difference between two molecular states. Analytical expressions are suggested for the locking angle and the slipping probability. Implication of the locking approximation for calculation of the quasiclassical scattering matrix is discussed. The second part considers the locking of the rotational angular momentum of a diatom in the decomposition of a triatomic complexes. We discuss here cases J = 1,2,3 and 4, but restrict ourselves to calculation of the so-called dynamic orientation of the diatomic fragment. The letter represents one of the characteristics of the locking matrix which in principle can be measured experimentally. The orientation is created as a result of the interplay between the adiabatic interaction in the atom- diatom exit channel and the rotationally non adiabatic coupling in the perturbed rotor region

  4. Injection locking of optomechanical oscillators via acoustic waves.

    Science.gov (United States)

    Huang, Ke; Hossein-Zadeh, Mani

    2018-04-02

    Injection locking is an effective technique for synchronization of oscillator networks and controlling the phase and frequency of individual oscillators. As such, exploring new mechanisms for injection locking of emerging oscillators is important for their usage in various systems. Here, we present the first demonstration of injection locking of a radiation pressure driven optomechanical oscillator (OMO) via acoustic waves. As opposed to previously reported techniques (based on pump modulation or direct application of a modulated electrostatic force), injection locking of OMO via acoustic waves does not require optical power modulation or physical contact with the OMO and it can be easily implemented on various platforms to lock different types of OMOs independent of their size and structure. Using this approach we have locked the phase and frequency of two distinct modes of a microtoroidal silica OMO to a piezoelectric transducer (PZT). We have characterized the behavior of the injection locked OMO with three acoustic excitation configurations and showed that even without proper acoustic impedance, matching the OMO can be locked to the PZT and tuned over 17 kHz with only -30 dBm of RF power fed to the PZT. The high efficiency, simplicity, and scalability of the proposed approach paves the road toward a new class of photonic systems that rely on synchronization of several OMOs to a single or multiple RF oscillators with applications in optical communication, metrology, and sensing. Beyond its practical applications, injection locking via acoustic waves can be used in fundamental studies in quantum optomechanics where thermal and optical isolation of the OMO are critical.

  5. Stable, tunable, quasimonoenergetic electron beams produced in a laser wakefield near the threshold for self-injection

    Directory of Open Access Journals (Sweden)

    S. Banerjee

    2013-03-01

    Full Text Available Stable operation of a laser-plasma accelerator near the threshold for electron self-injection in the blowout regime has been demonstrated with 25–60 TW, 30 fs laser pulses focused into a 3–4 millimeter length gas jet. Nearly Gaussian shape and high nanosecond contrast of the focused pulse appear to be critically important for controllable, tunable generation of 250–430 MeV electron bunches with a low-energy spread, ∼10  pC charge, a few-mrad divergence and pointing stability, and a vanishingly small low-energy background. The physical nature of the near-threshold behavior is examined using three-dimensional particle-in-cell simulations. Simulations indicate that properly locating the nonlinear focus of the laser pulse within the plasma suppresses continuous injection, thus reducing the low-energy tail of the electron beam.

  6. 49 CFR 236.338 - Mechanical locking required in accordance with locking sheet and dog chart.

    Science.gov (United States)

    2010-10-01

    ... locking sheet and dog chart. 236.338 Section 236.338 Transportation Other Regulations Relating to... in accordance with locking sheet and dog chart. Mechanical locking shall be in accordance with locking sheet and dog chart currently in effect. ...

  7. Generation of picosecond pulses and frequency combs in actively mode locked external ring cavity quantum cascade lasers

    International Nuclear Information System (INIS)

    Wójcik, Aleksander K.; Belyanin, Alexey; Malara, Pietro; Blanchard, Romain; Mansuripur, Tobias S.; Capasso, Federico

    2013-01-01

    We propose a robust and reliable method of active mode locking of mid-infrared quantum cascade lasers and develop its theoretical description. Its key element is the use of an external ring cavity, which circumvents fundamental issues undermining the stability of mode locking in quantum cascade lasers. We show that active mode locking can give rise to the generation of picosecond pulses and phase-locked frequency combs containing thousands of the ring cavity modes

  8. 49 CFR 236.330 - Locking dog of switch-and-lock movement.

    Science.gov (United States)

    2010-10-01

    ... 49 Transportation 4 2010-10-01 2010-10-01 false Locking dog of switch-and-lock movement. 236.330 Section 236.330 Transportation Other Regulations Relating to Transportation (Continued) FEDERAL RAILROAD... Rules and Instructions § 236.330 Locking dog of switch-and-lock movement. Locking dog of switch-and-lock...

  9. Heating (Gapless) Color-Flavor Locked Quark Matter

    DEFF Research Database (Denmark)

    Fukushima, Kenji; Kouvaris, Christoforos; Rajagopal, Krishna

    2005-01-01

    We explore the phase diagram of neutral quark matter at high baryon density as a function of the temperature T and the strange quark mass Ms. At T=0, there is a sharp distinction between the insulating color-flavor locked (CFL) phase, which occurs where Ms^2/mu 0 and Delta_2->0) cross. Because we...

  10. Circadian Clock Synchronization of the Cell Cycle in Zebrafish Occurs through a Gating Mechanism Rather Than a Period-phase Locking Process.

    Science.gov (United States)

    Laranjeiro, Ricardo; Tamai, T Katherine; Letton, William; Hamilton, Noémie; Whitmore, David

    2018-04-01

    Studies from a number of model systems have shown that the circadian clock controls expression of key cell cycle checkpoints, thus providing permissive or inhibitory windows in which specific cell cycle events can occur. However, a major question remains: Is the clock actually regulating the cell cycle through such a gating mechanism or, alternatively, is there a coupling process that controls the speed of cell cycle progression? Using our light-responsive zebrafish cell lines, we address this issue directly by synchronizing the cell cycle in culture simply by changing the entraining light-dark (LD) cycle in the incubator without the need for pharmacological intervention. Our results show that the cell cycle rapidly reentrains to a shifted LD cycle within 36 h, with changes in p21 expression and subsequent S phase timing occurring within the first few hours of resetting. Reentrainment of mitosis appears to lag S phase resetting by 1 circadian cycle. The range of entrainment of the zebrafish clock to differing LD cycles is large, from 16 to 32 hour periods. We exploited this feature to explore cell cycle entrainment at both the population and single cell levels. At the population level, cell cycle length is shortened or lengthened under corresponding T-cycles, suggesting that a 1:1 coupling mechanism is capable of either speeding up or slowing down the cell cycle. However, analysis at the single cell level reveals that this, in fact, is not true and that a gating mechanism is the fundamental method of timed cell cycle regulation in zebrafish. Cell cycle length at the single cell level is virtually unaltered with varying T-cycles.

  11. Breaking Carbon Lock-in

    DEFF Research Database (Denmark)

    Driscoll, Patrick Arthur

    2014-01-01

    This central focus of this paper is to highlight the ways in which path dependencies and increasing returns (network effects) serve to reinforce carbon lock-in in large-scale road transportation infrastructure projects. Breaking carbon lock-in requires drastic changes in the way we plan future...

  12. Payload Launch Lock Mechanism

    Science.gov (United States)

    Young, Ken (Inventor); Hindle, Timothy (Inventor)

    2014-01-01

    A payload launch lock mechanism includes a base, a preload clamp, a fastener, and a shape memory alloy (SMA) actuator. The preload clamp is configured to releasibly restrain a payload. The fastener extends, along an axis, through the preload clamp and into the base, and supplies a force to the preload clamp sufficient to restrain the payload. The SMA actuator is disposed between the base and the clamp. The SMA actuator is adapted to receive electrical current and is configured, upon receipt of the electrical current, to supply a force that causes the fastener to elongate without fracturing. The preload clamp, in response to the fastener elongation, either rotates or pivots to thereby release the payload.

  13. Gapless Color-Flavor-Locked Quark Matter

    DEFF Research Database (Denmark)

    Alford, Mark; Kouvaris, Christoforos; Rajagopal, Krishna

    2004-01-01

    In neutral cold quark matter that is sufficiently dense that the strange quark mass M_s is unimportant, all nine quarks (three colors; three flavors) pair in a color-flavor locked (CFL) pattern, and all fermionic quasiparticles have a gap. We argue that as a function of decreasing quark chemical...... potential mu or increasing M_s, there is a quantum phase transition from the CFL phase to a new ``gapless CFL phase'' in which only seven quasiparticles have a gap. The transition occurs where M_s^2/mu is approximately equal to 2*Delta, with Delta the gap parameter. Gapless CFL, like CFL, leaves unbroken...... a linear combination Qtilde of electric and color charges, but it is a Qtilde-conductor with a nonzero electron density. These electrons and the gapless quark quasiparticles make the low energy effective theory of the gapless CFL phase and, consequently, its astrophysical properties are qualitatively...

  14. 49 CFR 236.765 - Locking, mechanical.

    Science.gov (United States)

    2010-10-01

    ... 49 Transportation 4 2010-10-01 2010-10-01 false Locking, mechanical. 236.765 Section 236.765 Transportation Other Regulations Relating to Transportation (Continued) FEDERAL RAILROAD ADMINISTRATION... Locking, mechanical. An arrangement of locking bars, dogs, tappets, cross locking and other apparatus by...

  15. An evaluation of adherence in patients with multiple sclerosis newly initiating treatment with a self-injectable or an oral disease-modifying drug

    Directory of Open Access Journals (Sweden)

    Munsell M

    2016-12-01

    Full Text Available Michael Munsell,1 Molly Frean,1 Joseph Menzin,1 Amy L Phillips2 1Boston Health Economics, Inc., Waltham, MA, USA; 2Health Economics & Outcomes Research, EMD Serono Inc., Rockland, MA, USA Objective: As the multiple sclerosis (MS disease-modifying drug (DMD treatment options have expanded to include oral therapies, it is important to understand whether route of administration is associated with DMD adherence. The objective of this study was to compare adherence to DMDs in patients with MS newly initiating treatment with a self-injectable versus an oral DMD. Methods: This retrospective database study used IMS Health Real World Data Adjudicated Claims – US data between July 1, 2010 and June 30, 2014. Adherence was measured by medication possession ratio (MPR, calculated as the total number of treated days divided by the total number of days from the first treated day until the end of 12-month follow-up. A binary measure representing adherence (MPR ≥0.8 versus nonadherence (MPR <0.8 to therapy was used. Logistic regression evaluated the likelihood of adherence to index DMD type (self-injectable vs oral. Covariates included patient baseline characteristics (ie, age, sex, comorbidities and index DMD type. Results: The analysis included 7,207 self-injectable and 1,175 oral DMD-treated patients with MS. In unadjusted analyses, the proportion of patients adherent to therapy (MPR ≥0.8 did not differ significantly between the self-injectable (54.1% and the oral DMD cohorts (53.0%; P=0.5075. After controlling for covariates, index DMD type was not a significant predictor of adherence (odds ratio [OR] 1.062; 95% confidence interval [CI]: 0.937–1.202; P=0.3473. Higher likelihood of adherence was associated with male sex (OR 1.20; 95% CI: 1.085–1.335; P=0.0005 and age groups older than 18–34 years (ORs 1.220–1.331; P<0.01. Depression was associated with a lower likelihood of adherence (OR 0.618; 95% CI: 0.511–0.747; P<0.0001. Conclusion: Male

  16. Plasma-wall interaction and locked modes in the toroidal pinch experiment TPE-RX reversed-field pinch

    International Nuclear Information System (INIS)

    Pasqualini, D.; Martin, P.; Koguchi, H.; Yagi, Y.; Hirano, Y.; Sakakita, H.; Spizzo, G.

    2006-01-01

    The MHD instabilities that sustain the reversed-field pinch (RFP) configuration tend to phase-lock together and also to wall-lock, forming a bulging of the plasma column, called 'locked mode'. This phenomenon is of particular interest, since the locked mode causes a larger plasma resistivity, plasma cooling, and, in some cases, anomalous discharge termination. Up to now, studies of the locked mode have been focused on m=1 modes (being m the poloidal mode number). In this Letter we show that m=0 modes also play a role, based on the cross-check between magnetic spectra and toroidally resolved D α array measurements. (author)

  17. Escaping carbon lock-in

    International Nuclear Information System (INIS)

    Unruh, G.C.

    2002-01-01

    This article explores the climate policy implications of the arguments made in ''Understanding carbon lock-in'' (Unruh, 2000), which posited that industrial countries have become locked-into fossil fuel-based energy systems through path dependent processes driven by increasing returns to scale. Carbon lock-in arises through technological, organizational, social and institutional co-evolution, ''culminating'' in what was termed as techno-institutional complex (TIC). In order to resolve the climate problem, an escape from the lock-in condition is required. However, due to the self-referential nature of TIC, escape conditions are unlikely to be generated internally and it is argued here that erogenous forces are probably required. (author)

  18. Globalizing carbon lock-in

    International Nuclear Information System (INIS)

    Unruh, Gregory C.; Carrillo-Hermosilla, Javier

    2006-01-01

    This paper extends the arguments surrounding carbon lock-in elaborated in Unruh (Energy Policy 28 (2000) 817; 30 (2002) 317) to countries currently undergoing industrialization. It argues that, for numerous reasons, industrializing countries are unlikely to leapfrog carbon intensive energy development. On the contrary, carbon lock-in may be globalizing and could further constrain climate change mitigation options. It is then argued that many policy recommendations ignore carbon lock-in, possibly limiting their potential for successful implementation. The paper then discusses four policy approaches that appear to have advantages given lock-in conditions. It is recognized, however, that relative ease of implementation does not necessarily equate with superiority. Instead, it is merely a path dependent outcome of past development decisions. Pursuing policies on the basis of relative implementation ease may help address the issue of climate change, but could also result in sub-optimal outcomes along other dimensions of sustainable development

  19. Research of mechanism of density lock

    International Nuclear Information System (INIS)

    Wang Shengfei; Yan Changqi; Gu Haifeng

    2010-01-01

    Mechanism of density lock was analyzed according to the work conditions of density lock. The results showed that: the stratification with no disturbance satisfied the work conditions of density lock; fluids between the stratification were not mixed at the condition of connected to each other; the density lock can be open automatically by controlled the pressure balance at the stratification. When disturbance existed, the stratification might be broken and mass would be transferred by convection. The stability of stratification can be enhanced by put the special structure in density lock to ensure the normal work of density lock. At last, the minimum of heat loss in density lock was also analyzed. (authors)

  20. Hew Locke: House of Cards

    OpenAIRE

    Reckitt, Helena; Joyce, Julie; Locke, Hew

    2004-01-01

    ‘Hew Locke: House of Cards’ featured a selection of the artist's portraits of British royalty in various media, and his response to other trappings of the monarchy and empire. The show included works previously exhibited at the Luckman Gallery, Los Angeles, in tandem with a newly commissioned coat of arms, and other recent works. \\ud \\ud Locke draws from everyday sources, ranging from items found in London's Brixton Market to discount fabric shops and thrift stores. Other sources of inspirati...

  1. John locke on personal identity.

    Science.gov (United States)

    Nimbalkar, Namita

    2011-01-01

    John Locke speaks of personal identity and survival of consciousness after death. A criterion of personal identity through time is given. Such a criterion specifies, insofar as that is possible, the necessary and sufficient conditions for the survival of persons. John Locke holds that personal identity is a matter of psychological continuity. He considered personal identity (or the self) to be founded on consciousness (viz. memory), and not on the substance of either the soul or the body.

  2. John Locke on Personal Identity**

    OpenAIRE

    Nimbalkar, Namita

    2011-01-01

    John Locke speaks of personal identity and survival of consciousness after death. A criterion of personal identity through time is given. Such a criterion specifies, insofar as that is possible, the necessary and sufficient conditions for the survival of persons. John Locke holds that personal identity is a matter of psychological continuity. He considered personal identity (or the self) to be founded on consciousness (viz. memory), and not on the substance of either the soul or the body.

  3. Biomechanics of far cortical locking.

    Science.gov (United States)

    Bottlang, Michael; Feist, Florian

    2011-02-01

    The development of far cortical locking (FCL) was motivated by a conundrum: locked plating constructs provide inherently rigid stabilization, yet they should facilitate biologic fixation and secondary bone healing that relies on flexible fixation to stimulate callus formation. Recent studies have confirmed that the high stiffness of standard locked plating constructs can suppress interfragmentary motion to a level that is insufficient to reliably promote secondary fracture healing by callus formation. Furthermore, rigid locking screws cause an uneven stress distribution that may lead to stress fracture at the end screw and stress shielding under the plate. This review summarizes four key features of FCL constructs that have been shown to enhance fixation and healing of fractures: flexible fixation, load distribution, progressive stiffening, and parallel interfragmentary motion. Specifically, flexible fixation provided by FCL reduces the stiffness of a locked plating construct by 80% to 88% to actively promote callus proliferation similar to an external fixator. Load is evenly distributed between FCL screws to mitigate stress risers at the end screw. Progressive stiffening occurs by near cortex support of FCL screws and provides additional support under elevated loading. Finally, parallel interfragmentary motion by the S-shaped flexion of FCL screws promotes symmetric callus formation. In combination, these features of FCL constructs have been shown to induce more callus and to yield significantly stronger and more consistent healing compared with standard locked plating constructs. As such, FCL constructs function as true internal fixators by replicating the biomechanical behavior and biologic healing response of external fixators.

  4. Towards attosecond synchronization of remote mode-locked lasers using stabilized transmission of optical comb frequencies

    Science.gov (United States)

    Wilcox, R. B.; Byrd, J. M.; Doolittle, L. R.; Holzwarth, R.; Huang, G.

    2011-09-01

    We propose a method of synchronizing mode-locked lasers separated by hundreds of meters with the possibility of achieving sub-fs performance by locking the phases of corresponding lines in the optical comb spectrum. The optical phase from one comb line is transmitted to the remote laser over an interferometrically stabilized link by locking a single frequency laser to a comb line with high phase stability. We describe how these elements are integrated into a complete system and estimate the potential performance.

  5. Outdraft at Lock Approach, Tom Bevill Lock and Dam, Alabama: Hydraulic Model Investigation

    National Research Council Canada - National Science Library

    Lynch, Gary

    2001-01-01

    .... The lock is connected to the dam with a 150-ft abutment wall. A strong crosscurrent or outdraft existing in and around the upstream lock entrance causes difficulty for tow traffic navigating the lock...

  6. Assessing carbon lock-in

    International Nuclear Information System (INIS)

    Erickson, Peter; Kartha, Sivan; Lazarus, Michael; Tempest, Kevin

    2015-01-01

    The term ‘carbon lock-in’ refers to the tendency for certain carbon-intensive technological systems to persist over time, ‘locking out’ lower-carbon alternatives, and owing to a combination of linked technical, economic, and institutional factors. These technologies may be costly to build, but relatively inexpensive to operate and, over time, they reinforce political, market, and social factors that make it difficult to move away from, or ‘unlock’ them. As a result, by investing in assets prone to lock-in, planners and investors restrict future flexibility and increase the costs of achieving agreed climate protection goals. Here, we develop a straight-forward approach to assess the speed, strength, and scale of carbon lock-in for major energy-consuming assets in the power, buildings, industry, and transport sectors. We pilot the approach at the global level, finding that carbon lock-in is greatest, globally, for coal power plants, gas power plants, and oil-based vehicles. The approach can be readily applied at the national or regional scale, and may be of particular relevance to policymakers interested in enhancing flexibility in their jurisdictions for deeper emissions cuts in the future, and therefore in limiting the future costs associated with ‘stranded assets’. (letter)

  7. The locking and unlocking thresholds for tearing modes in a cylindrical tokamak

    Energy Technology Data Exchange (ETDEWEB)

    Huang, Wenlong [CAS Key Laboratory of Geospace Environment and Department of Modern Physics, University of Science and Technology of China, Hefei, Anhui 230026 (China); Zhu, Ping, E-mail: pzhu@ustc.edu.cn [CAS Key Laboratory of Geospace Environment and Department of Modern Physics, University of Science and Technology of China, Hefei, Anhui 230026 (China); Department of Engineering Physics, University of Wisconsin-Madison, Madison, Wisconsin 53706 (United States)

    2016-03-15

    The locking and unlocking thresholds for tearing modes are in general different. In this work, the physics origin for this difference is illustrated from theory analysis, and a numerical procedure is developed to find both locking and unlocking thresholds. In particular, a new scaling law for the unlocking threshold that is valid in both weak and strong rotation regimes has been derived from the lowest amplitude of the RMP (resonant magnetic perturbation) allowed for the locked-mode solution. Above the unlocking threshold, the criterion for the phase-flip instability is extended to identify the entire locked-mode states. Two different regimes of the RMP amplitude in terms of the accessibility of the locked-mode states have been found. In the first regime, the locked-mode state may or may not be accessible depending on the initial conditions of an evolving island. In the second regime, the locked-mode state can always be reached regardless of the initial conditions of the tearing mode. The lowest RMP amplitude for the second regime is determined to be the mode-locking threshold. The different characteristics of the two regimes above the unlocking threshold reveal the underlying physics for the gap between the locking and unlocking thresholds and provide an explanation for the closely related and widely observed hysteresis phenomena in island evolution during the sweeping process of the RMP amplitude up and down across that threshold gap.

  8. Magnetized color flavor locked state and compact stars

    CERN Document Server

    Felipe, R Gonzalez; Martinez, A Perez

    2010-01-01

    The stability of the color flavor locked phase in the presence of a strong magnetic field is investigated within the phenomenological MIT bag model, taking into account the variation of the strange quark mass, the baryon density, the magnetic field, as well as the bag and gap parameters. It is found that the minimum value of the energy per baryon in a color flavor locked state at vanishing pressure is lower than the corresponding one for unpaired magnetized strange quark matter and, as the magnetic field increases, the energy per baryon decreases. This implies that magnetized color flavor locked matter is more stable and could become the ground state inside neutron stars. The mass-radius relation for such stars is also studied.

  9. Coupled optical resonance laser locking.

    Science.gov (United States)

    Burd, S C; du Toit, P J W; Uys, H

    2014-10-20

    We have demonstrated simultaneous laser frequency stabilization of a UV and IR laser, to coupled transitions of ions in the same spectroscopic sample, by detecting only the absorption of the UV laser. Separate signals for locking the different lasers are obtained by modulating each laser at a different frequency and using lock-in detection of a single photodiode signal. Experimentally, we simultaneously lock a 369 nm and a 935 nm laser to the (2)S(1/2) → (2)(P(1/2) and (2)D(3/2) → (3)D([3/2]1/2) transitions, respectively, of Yb(+) ions generated in a hollow cathode discharge lamp. Stabilized lasers at these frequencies are required for cooling and trapping Yb(+) ions, used in quantum information and in high precision metrology experiments. This technique should be readily applicable to other ion and neutral atom systems requiring multiple stabilized lasers.

  10. Injection-locked single-mode VCSEL for orthogonal multiplexing and amplitude noise suppression

    DEFF Research Database (Denmark)

    Chipouline, Arkadi; Lyubopytov, Vladimir S.; Malekizandi, Mohammadreza

    2017-01-01

    It has been shown earlier, that the injection locked semiconductor lasers enable effective amplitude noise suppression [1] and makes possible an extra level of signal multiplexing-orthogonal modulation [2], where DPSK and ASK NRZ channels propagate at the same wavelength [3]. In our work we use...... an injection-locked 1550 nm VCSEL as a slave laser providing separation of amplitude and phase modulations, carrying independent information flows. To validate the possibility of phase modulation extraction by an injection-locked VCSEL, an experimental setup shown in Fig. 1 has been built....

  11. Analysis of timing jitter in external-cavity mode-locked semiconductor lasers

    DEFF Research Database (Denmark)

    Mulet, Josep; Mørk, Jesper

    2006-01-01

    We develop a comprehensive theoretical description of passive mode-locking in external-cavity mode-locked semiconductor lasers based on a fully distributed time-domain approach. The model accounts for the dispersion of both gain and refractive index, nonlinear gain saturation from ultrafast...... processes, self-phase modulation, and spontaneous emission noise. Fluctuations of the mode-locked pulses are characterized from the fully distributed model using direct integration of noise-skirts in the phase-noise spectrum and the soliton perturbations introduced by Haus. We implement the model in order...

  12. Low-cost, digital lock-in module with external reference for coating glass transmission/reflection spectrophotometer

    Science.gov (United States)

    Alonso, R.; Villuendas, F.; Borja, J.; Barragán, L. A.; Salinas, I.

    2003-05-01

    A versatile, low-cost, digital signal processor (DSP) based lock-in module with external reference is described. This module is used to implement an industrial spectrophotometer for measuring spectral transmission and reflection of automotive and architectonic coating glasses over the ultraviolet, visible and near-infrared wavelength range. The light beams are modulated with an optical chopper. A digital phase-locked loop (DPLL) is used to lock the lock-in to the chop frequency. The lock-in rejects the ambient radiation and permits the spectrophotometer to work in the presence of ambient light. The algorithm that implements the dual lock-in and the DPLL in the DSP56002 evaluation module from Motorola is described. The use of a DSP allows implementation of the lock-in and DPLL by software, which gives flexibility and programmability to the system. Lock-in module cost, under 300 euro, is an important parameter taking into account that two modules are used in the system. Besides, the algorithms implemented in this DSP can be directly implemented in the latest DSP generations. The DPLL performance and the spectrophotometer are characterized. Capture and lock DPLL ranges have been measured and checked to be greater than the chop frequency drifts. The lock-in measured frequency response shows that the lock-in performs as theoretically predicted.

  13. High performance mode locking characteristics of single section quantum dash lasers.

    Science.gov (United States)

    Rosales, Ricardo; Murdoch, S G; Watts, R T; Merghem, K; Martinez, Anthony; Lelarge, Francois; Accard, Alain; Barry, L P; Ramdane, Abderrahim

    2012-04-09

    Mode locking features of single section quantum dash based lasers are investigated. Particular interest is given to the static spectral phase profile determining the shape of the mode locked pulses. The phase profile dependence on cavity length and injection current is experimentally evaluated, demonstrating the possibility of efficiently using the wide spectral bandwidth exhibited by these quantum dash structures for the generation of high peak power sub-picosecond pulses with low radio frequency linewidths.

  14. Automatic locking knee brace joint

    Science.gov (United States)

    Weddendorf, Bruce (Inventor)

    1995-01-01

    This invention is an apparatus for controlling the pivotal movement of a knee brace comprising a tang-and-clevis joint that has been uniquely modified. Both the tang and the clevis have a set of teeth that, when engaged, can lock the tang and the clevis together. In addition, the tang is biased away from the clevis. Consequently, when there is no axial force (i.e., body weight) on the tang, the tang is free to pivot within the clevis. However, when an axial force is exerted on the tang, the tang is pushed into the clevis, both sets of teeth engage, and the tang and the clevis lock together.

  15. PWR integral tie plate and locking mechanism

    International Nuclear Information System (INIS)

    Flora, B.S.; Osborne, J.L.

    1980-01-01

    A locking mechanism for securing an upper tie plate to the tie rods of a nuclear fuel bundle is described. The mechanism includes an upper tie plate assembly and locking sleeves fixed to the ends of the tie rods. The tie plate is part of the upper tie plate assembly and is secured to the fuel bundle by securing the entire upper tie plate assembly to the locking sleeves fixed to the tie rods. The assembly includes, in addition to the tie plate, locking nuts for engaging the locking sleeves, retaining sleeves to operably connect the locking nuts to the assembly, a spring biased reaction plate to restrain the locking nuts in the locked position and a means to facilitate the removal of the entire assembly as a unit from the fuel bundle

  16. One-minute mental status examination for category fluency is more useful than mini-mental state examination to evaluate the reliability of insulin self-injection in elderly diabetic patients.

    Science.gov (United States)

    Yajima, Ken; Matsushita, Takaya; Sumitomo, Hidetaka; Sakurai, Hirofumi; Katayama, Takashi; Kanno, Kazuo; Sakai, Masashi; Shigeta, Masayuki; Shirabe, Shinichiro; Nakano, Tadasumi; Nishimura, Kazuhiro; Ueki, Akio; Kitaoka, Masafumi

    2014-05-04

    We investigated the factors associated with the reliability of insulin self-injection in elderly diabetic patients receiving insulin therapy. We enrolled diabetic patients aged ≥65 years and receiving insulin therapy, and assessed their cognitive function by the mini-mental state examination and 1-min mental status examination for category fluency. We also observed their technique of insulin self-injection, and evaluated whether or not patients were able to inject insulin by themselves according to nine defined details in terms of insulin self-injection. The predictive factors for the reliability of insulin self-injection were determined by univariate and multivariate logistic regression analysis. There were 278 participants (135 males, 143 females) enrolled in the present study. According to multivariate logistic regression analysis, only the 1-min mental status examination score was found to be a significant independent predictor of the reliability of insulin self-injection (odds ratio 0.75; 95% confidence interval 0.62-0.90; P = 0.002). The 1-min mental status examination for category fluency can be considered more useful than mini-mental state examination to evaluate the reliability of insulin self-injection in elderly diabetic patients receiving insulin therapy.

  17. The variable finesse locking technique

    International Nuclear Information System (INIS)

    Acernese, F; Al-Shourbagy, M

    2006-01-01

    Virgo is a power recycled Michelson interferometer, with 3 km long Fabry-Perot cavities in the arms. The locking of the interferometer has been obtained with an original lock acquisition technique. The main idea is to lock the instrument away from its working point. Lock is obtained by misaligning the power recycling mirror and detuning the Michelson from the dark fringe. In this way, a good fraction of light escapes through the antisymmetric port and the power build-up inside the recycling cavity is extremely low. The benefit is that all the degrees of freedom are controlled when they are almost decoupled, and the linewidth of the recycling cavity is large. The interferometer is then adiabatically brought on to the dark fringe. This technique is referred to as variable finesse, since the recycling cavity is considered as a variable finesse Fabry-Perot. This technique has been widely tested and allows us to reach the dark fringe in few minutes, in an essentially deterministic way

  18. Coupled optical resonance laser locking

    CSIR Research Space (South Africa)

    Burd, CC

    2014-10-01

    Full Text Available We have demonstrated simultaneous laser frequency stabilization of a UV and IR laser, to coupled transitions of ions in the same spectroscopic sample, by detecting only the absorption of the UV laser. Separate signals for locking the different...

  19. 49 CFR 236.705 - Bar, locking.

    Science.gov (United States)

    2010-10-01

    ... 49 Transportation 4 2010-10-01 2010-10-01 false Bar, locking. 236.705 Section 236.705..., MAINTENANCE, AND REPAIR OF SIGNAL AND TRAIN CONTROL SYSTEMS, DEVICES, AND APPLIANCES Definitions § 236.705 Bar, locking. A bar in an interlocking machine to which the locking dogs are attached. ...

  20. Bilateral locked facets in the thoracic spine

    NARCIS (Netherlands)

    M.H.A. Willems; Braakman, R. (Reinder); B. van Linge (Bert)

    1984-01-01

    textabstractTwo cases of traumatic bilateral locked facets in the thoracic spine are reported. Both patients had only minor neurological signs. They both made a full neurological recovery after surgical reduction of the locked facets. Bilateral locked facets are very uncommon in the thoracic spine.

  1. 49 CFR 236.761 - Locking, electric.

    Science.gov (United States)

    2010-10-01

    ... 49 Transportation 4 2010-10-01 2010-10-01 false Locking, electric. 236.761 Section 236.761 Transportation Other Regulations Relating to Transportation (Continued) FEDERAL RAILROAD ADMINISTRATION... Locking, electric. The combination of one or more electric locks and controlling circuits by means of...

  2. 49 CFR 236.105 - Electric lock.

    Science.gov (United States)

    2010-10-01

    ... 49 Transportation 4 2010-10-01 2010-10-01 false Electric lock. 236.105 Section 236.105 Transportation Other Regulations Relating to Transportation (Continued) FEDERAL RAILROAD ADMINISTRATION...: All Systems Inspections and Tests; All Systems § 236.105 Electric lock. Electric lock, except forced...

  3. 49 CFR 236.757 - Lock, electric.

    Science.gov (United States)

    2010-10-01

    ... 49 Transportation 4 2010-10-01 2010-10-01 false Lock, electric. 236.757 Section 236.757... Lock, electric. A device to prevent or restrict the movement of a lever, a switch or a movable bridge, unless the locking member is withdrawn by an electrical device, such as an electromagnet, solenoid or...

  4. 49 CFR 236.768 - Locking, time.

    Science.gov (United States)

    2010-10-01

    ... 49 Transportation 4 2010-10-01 2010-10-01 false Locking, time. 236.768 Section 236.768... Locking, time. A method of locking, either mechanical or electrical, which, after a signal has been caused to display an aspect to proceed, prevents, until after the expiration of a predetermined time...

  5. Tidal locking of habitable exoplanets

    Science.gov (United States)

    Barnes, Rory

    2017-12-01

    Potentially habitable planets can orbit close enough to their host star that the differential gravity across their diameters can produce an elongated shape. Frictional forces inside the planet prevent the bulges from aligning perfectly with the host star and result in torques that alter the planet's rotational angular momentum. Eventually the tidal torques fix the rotation rate at a specific frequency, a process called tidal locking. Tidally locked planets on circular orbits will rotate synchronously, but those on eccentric orbits will either librate or rotate super-synchronously. Although these features of tidal theory are well known, a systematic survey of the rotational evolution of potentially habitable exoplanets using classic equilibrium tide theories has not been undertaken. I calculate how habitable planets evolve under two commonly used models and find, for example, that one model predicts that the Earth's rotation rate would have synchronized after 4.5 Gyr if its initial rotation period was 3 days, it had no satellites, and it always maintained the modern Earth's tidal properties. Lower mass stellar hosts will induce stronger tidal effects on potentially habitable planets, and tidal locking is possible for most planets in the habitable zones of GKM dwarf stars. For fast-rotating planets, both models predict eccentricity growth and that circularization can only occur once the rotational frequency is similar to the orbital frequency. The orbits of potentially habitable planets of very late M dwarfs ([InlineEquation not available: see fulltext.]) are very likely to be circularized within 1 Gyr, and hence, those planets will be synchronous rotators. Proxima b is almost assuredly tidally locked, but its orbit may not have circularized yet, so the planet could be rotating super-synchronously today. The evolution of the isolated and potentially habitable Kepler planet candidates is computed and about half could be tidally locked. Finally, projected TESS planets

  6. Dynamics of Tidally Locked, Ultrafast Rotating Atmospheres

    Science.gov (United States)

    Tan, Xianyu; Showman, Adam P.

    2017-10-01

    Tidally locked gas giants, which exhibit a novel regime of day-night thermal forcing and extreme stellar irradiation, are typically in several-day orbits, implying slow rotation and a modest role for rotation in the atmospheric circulation. Nevertheless, there exist a class of gas-giant, highly irradiated objects - brown dwarfs orbiting white dwarfs in extremely tight orbits - whose orbital and hence rotation periods are as short as 1-2 hours. Spitzer phase curves and other observations have already been obtained for this fascinating class of objects, which raise fundamental questions about the role of rotation in controlling the circulation. So far, most modeling studies have investigated rotation periods exceeding a day, as appropriate for typical hot Jupiters. In this work we investigate the dynamics of tidally locked atmospheres in shorter rotation periods down to about two hours. With increasing rotation rate (decreasing rotation period), we show that the width of the equatorial eastward jet decreases, consistent with the narrowing of wave-mean-flow interacting region due to decrease of the equatorial deformation radius. The eastward-shifted equatorial hot spot offset decreases accordingly, and the westward-shifted hot regions poleward of the equatorial jet associated with Rossby gyres become increasingly distinctive. At high latitudes, winds becomes weaker and more geostrophic. The day-night temperature contrast becomes larger due to the stronger influence of rotation. Our simulated atmospheres exhibit small-scale variability, presumably caused by shear instability. Unlike typical hot Jupiters, phase curves of fast-rotating models show an alignment of peak flux to secondary eclipse. Our results have important implications for phase curve observations of brown dwarfs orbiting white dwarfs in ultra tight orbits.

  7. 49 CFR 236.766 - Locking, movable bridge.

    Science.gov (United States)

    2010-10-01

    ... 49 Transportation 4 2010-10-01 2010-10-01 false Locking, movable bridge. 236.766 Section 236.766... Locking, movable bridge. The rail locks, bridge locks, bolt locks, circuit controllers, and electric locks used in providing interlocking protection at a movable bridge. ...

  8. Narrow-band modulation of semiconductor lasers at millimeter wave frequencies (7100 GHz) by mode locking

    International Nuclear Information System (INIS)

    Lau, K.Y.

    1990-01-01

    This paper reports on the possibility of mode locking a semiconductor laser at millimeter wave frequencies approaching and beyond 100 GHz which was investigated theoretically and experimentally. It is found that there are no fundamental theoretical limitations in mode locking at frequencies below 100 GHz. AT these high frequencies, only a few modes are locked and the output usually takes the form of a deep sinusoidal modulation which is synchronized in phase with the externally applied modulation at the intermodal heat frequency. This can be regarded for practical purposes as a highly efficient means of directly modulating an optical carrier over a narrow band at millimeter wave frequencies. Both active and passive mode locking are theoretically possible. Experimentally, predictions on active mode locking have been verified in prior publications up to 40 GHz. For passive mode locking, evidence consistent with passive mode locking was observed in an inhomogeneously pumped GaAIAs laser at a frequency of approximately 70 GHz. A large differential gain-absorption ratio such as that present in an inhomogeneously pumped single quantum well laser is necessary for pushing the passive mode-locking frequency beyond 100 GHz

  9. Is John Locke a democrat?

    DEFF Research Database (Denmark)

    Svensson, Palle

      Over recent years there has been a tendency to present John Locke as an equalitarian democrat (Ashcraft) and being close to the political views of the levellers (Waldron). This is not a completely new interpretation (Kendall, 1941), but contrasts with the prevalent view presented in textbooks (......, criteria for a democratic process, and the institutions of polyarchy. The conclusion has implications for the relationship between political liberalism and constitutionalism on the one hand and democracy on the other....

  10. Digital lock-in amplifier based on soundcard interface for physics laboratory

    Science.gov (United States)

    Sinlapanuntakul, J.; Kijamnajsuk, P.; Jetjamnong, C.; Chotikaprakhan, S.

    2017-09-01

    The purpose of this paper is to develop a digital lock-in amplifier based on soundcard interface for undergraduate physics laboratory. Both series and parallel RLC circuit laboratory are tested because of its well-known, easy to understand and simple confirm. The sinusoidal signal at the frequency of 10 Hz - 15 kHz is generated to the circuits. The amplitude and phase of the voltage drop across the resistor, R are measured in 10 step decade. The signals from soundcard interface and lock-in amplifier are compared. The results give a good correlation. It indicates that the design digital lock-in amplifier is promising for undergraduate physic laboratory.

  11. Laser dynamics of asynchronous rational harmonic mode-locked fiber soliton lasers

    International Nuclear Information System (INIS)

    Jyu, Siao-Shan; Jiang, Guo-Hao; Lai, Yinchieh

    2013-01-01

    Laser dynamics of asynchronous rational harmonic mode-locked (ARHM) fiber soliton lasers are investigated in detail. In particular, based on the unique laser dynamics of asynchronous mode-locking, we have developed a new method for determining the effective active modulation strength in situ for ARHM lasers. By measuring the magnitudes of the slowly oscillating pulse timing position and central frequency, the effective phase modulation strength at the multiplication frequency of rational harmonic mode-locking can be accurately inferred. The method can be a very useful tool for developing ARHM fiber lasers. (paper)

  12. Active locking and entanglement in type II optical parametric oscillators

    Science.gov (United States)

    Ruiz-Rivas, Joaquín; de Valcárcel, Germán J.; Navarrete-Benlloch, Carlos

    2018-02-01

    Type II optical parametric oscillators are amongst the highest-quality sources of quantum-correlated light. In particular, when pumped above threshold, such devices generate a pair of bright orthogonally-polarized beams with strong continuous-variable entanglement. However, these sources are of limited practical use, because the entangled beams emerge with different frequencies and a diffusing phase difference. It has been proven that the use of an internal wave-plate coupling the modes with orthogonal polarization is capable of locking the frequencies of the emerging beams to half the pump frequency, as well as reducing the phase-difference diffusion, at the expense of reducing the entanglement levels. In this work we characterize theoretically an alternative locking mechanism: the injection of a laser at half the pump frequency. Apart from being less invasive, this method should allow for an easier real-time experimental control. We show that such an injection is capable of generating the desired phase locking between the emerging beams, while still allowing for large levels of entanglement. Moreover, we find an additional region of the parameter space (at relatively large injections) where a mode with well defined polarization is in a highly amplitude-squeezed state.

  13. Safety lock for radiography exposure device

    International Nuclear Information System (INIS)

    Gaines, T.M.

    1982-01-01

    A safety lock for securing a radiation source in a radiography exposure device is disclosed. The safety lock prevents the inadvertent extension of the radiation source from the exposure device. The exposure devices are used extensively in industry for nondestructive testing of metal materials for defect. Unnecessary exposure of the radiographer or operator occurs not infrequently due to operator's error in believing that the radiation source is secured in the exposure device when, in fact, it is not. The present invention solves this problem of unnecessary exposure by releasingly trapping the radiation source in the shield of the radiography exposure device each time the source is retracted therein so that it is not inadvertently extended therefrom without the operator resetting the safety lock, thereby releasing the radiation source. Further, the safety lock includes an indicator which indicates when the source is trapped in the exposure device and also when it is untrapped. The safety lock is so designed that it does not prevent the return of the source to the trapped, shielded position in the exposure device. Further the safety lock includes a key means for locking the radiation source in the trapped position. The key means cannot be actuated until said radiation source is in said trapped position to further insure the safety lock cannot be inadvertently locked with the source untrapped and thus still extendable from the exposure device

  14. Double pass locking and spatial mode locking for gravitational wave detectors

    CERN Document Server

    Cusack, B J; Slagmolen, B; Vine, G D; Gray, M B; McClelland, D E

    2002-01-01

    We present novel techniques for overcoming problems relating to the use of high-power lasers in mode cleaner cavities for second generation laser interferometric gravitational wave detectors. Rearranging the optical components into a double pass locking regime can help to protect locking detectors from damage. Modulator thermal lensing can be avoided by using a modulation-free technique such as tilt locking, or its recently developed cousin, flip locking.

  15. A pulsated weak-resonant-cavity laser diode with transient wavelength scanning and tracking for injection-locked RZ transmission.

    Science.gov (United States)

    Lin, Gong-Ru; Chi, Yu-Chieh; Liao, Yu-Sheng; Kuo, Hao-Chung; Liao, Zhi-Wang; Wang, Hai-Lin; Lin, Gong-Cheng

    2012-06-18

    By spectrally slicing a single longitudinal-mode from a master weak-resonant-cavity Fabry-Perot laser diode with transient wavelength scanning and tracking functions, the broadened self-injection-locking of a slave weak-resonant-cavity Fabry-Perot laser diode is demonstrated to achieve bi-directional transmission in a 200-GHz array-waveguide-grating channelized dense-wavelength-division-multiplexing passive optical network system. Both the down- and up-stream slave weak-resonant-cavity Fabry-Perot laser diodes are non-return-to-zero modulated below threshold and coherently injection-locked to deliver the pulsed carrier for 25-km bi-directional 2.5 Gbits/s return-to-zero transmission. The master weak-resonant-cavity Fabry-Perot laser diode is gain-switched at near threshold condition and delivers an optical coherent pulse-train with its mode linewidth broadened from 0.2 to 0.8 nm by transient wavelength scanning, which facilitates the broadband injection-locking of the slave weak-resonant-cavity Fabry-Perot laser diodes with a threshold current reducing by 10 mA. Such a transient wavelength scanning induced spectral broadening greatly releases the limitation on wavelength injection-locking range required for the slave weak-resonant-cavity Fabry-Perot laser diode. The theoretical modeling and numerical simulation on the wavelength scanning and tracking effects of the master and slave weak-resonant-cavity Fabry-Perot laser diodes are performed. The receiving power sensitivity for back-to-back transmission at bit-error-rate transmission is less than 2 dB for all 16 channels.

  16. From ultra-dense QCD towards NICA densities: Color-flavor locking and other color superconductors

    Energy Technology Data Exchange (ETDEWEB)

    Schmitt, Andreas [University of Southampton, Mathematical Sciences and STAG Research Centre, Southampton (United Kingdom)

    2016-08-15

    At asymptotically large densities and sufficiently low temperatures, quark matter is a color superconductor in the color-flavor locked phase. I present a brief discussion of this phase and of possible other color superconductors that may appear at densities reached at NICA and in the interior of compact stars. (orig.)

  17. Dispersion engineering of mode-locked fibre lasers

    Science.gov (United States)

    Woodward, R. I.

    2018-03-01

    Mode-locked fibre lasers are important sources of ultrashort pulses, where stable pulse generation is achieved through a balance of periodic amplitude and phase evolutions. A range of distinct cavity pulse dynamics have been revealed, arising from the interplay between dispersion and nonlinearity in addition to dissipative processes such as filtering. This has led to the discovery of numerous novel operating regimes, offering significantly improved laser performance. In this Topical Review, we summarise the main steady-state pulse dynamics reported to date through cavity dispersion engineering, including average solitons, dispersion-managed solitons, dissipative solitons, giant-chirped pulses and similaritons. Characteristic features and the stabilisation mechanism of each regime are described, supported by numerical modelling, in addition to the typical performance and limitations. Opportunities for further pulse energy scaling are discussed, in addition to considering other recent advances including automated self-tuning cavities and fluoride-fibre-based mid-infrared mode-locked lasers.

  18. Frequency locking of a field-widened Michelson interferometer based on optimal multi-harmonics heterodyning.

    Science.gov (United States)

    Cheng, Zhongtao; Liu, Dong; Zhou, Yudi; Yang, Yongying; Luo, Jing; Zhang, Yupeng; Shen, Yibing; Liu, Chong; Bai, Jian; Wang, Kaiwei; Su, Lin; Yang, Liming

    2016-09-01

    A general resonant frequency locking scheme for a field-widened Michelson interferometer (FWMI), which is intended as a spectral discriminator in a high-spectral-resolution lidar, is proposed based on optimal multi-harmonics heterodyning. By transferring the energy of a reference laser to multi-harmonics of different orders generated by optimal electro-optic phase modulation, the heterodyne signal of these multi-harmonics through the FWMI can reveal the resonant frequency drift of the interferometer very sensitively within a large frequency range. This approach can overcome the locking difficulty induced by the low finesse of the FWMI, thus contributing to excellent locking accuracy and lock acquisition range without any constraint on the interferometer itself. The theoretical and experimental results are presented to verify the performance of this scheme.

  19. Comparing the Overhead of Lock-based and Lock-free Implementations of Priority Queues

    DEFF Research Database (Denmark)

    Passas, Stavros; Karlsson, Sven

    2011-01-01

    . In this paper, we compare a lock-free implementation of a priority queue with a lock-based implementation. We perform experiments with processors of different generations and observe large performance differences for lock-free data structures depending on the processor generation. The lock-free implementation...... performs much better on the most recent processor generation. We investigate this performance trend, using a set of micro-benchmarks and show a significant difference in the overhead of atomic operations between processor generations. The lock-free implementation executes approximately three times as many...

  20. Past, Present, Future Erosion at Locke Island

    Energy Technology Data Exchange (ETDEWEB)

    Bjornstad, Bruce N.

    2006-08-08

    This report describes and documents the erosion that has occurred along the northeast side of Locke Island over the last 10 to 20 years. The principal cause of this erosion is the massive Locke Island landslide complex opposite the Columbia River along the White Bluffs, which constricts the flow of the river and deflects the river's thalweg southward against the island.

  1. An automatic mode-locked system for passively mode-locked fiber laser

    Science.gov (United States)

    Li, Sha; Xu, Jun; Chen, Guoliang; Mei, Li; Yi, Bo

    2013-12-01

    This paper designs and implements one kind of automatic mode-locked system. It can adjust a passively mode-locked fiber laser to keep steady mode-locked states automatically. So the unsteadiness of traditional passively mode-locked fiber laser can be avoided. The system transforms optical signals into electrical pulse signals and sends them into MCU after processing. MCU calculates the frequency of the signals and judges the state of the output based on a quick judgment algorithm. A high-speed comparator is used to check the signals and the comparison voltage can be adjusted to improve the measuring accuracy. Then by controlling two polarization controllers at an angle of 45degrees to each other, MCU extrudes the optical fibers to change the polarization until it gets proper mode-locked output. So the system can continuously monitor the output signal and get it back to mode-locked states quickly and automatically. States of the system can be displayed on the LCD and PC. The parameters of the steady mode-locked states can be stored into an EEPROM so that the system will get into mode-locked states immediately next time. Actual experiments showed that, for a 6.238MHz passively mode-locked fiber lasers, the system can get into steady mode-locked states automatically in less than 90s after starting the system. The expected lock time can be reduced to less than 20s after follow up improvements.

  2. Design and Development of Advanced Lock-in Amplifier and its Application

    Directory of Open Access Journals (Sweden)

    Bhagyajyothi

    2013-06-01

    Full Text Available Lock-in amplifiers are used to process the analog signals even in the presence of noise sources of greater amplitude. In the present study, an attempt is made to design a C8051F060 microcontroller based lock-in amplifier. The microcontroller contains all the on-chip features to design a single-chip lock-in amplifier. The reference signal for lock-in amplifier is generated by on-chip digital-to-analog converter (DAC and timer. The signal whose amplitude is to be measured is acquired by on-chip ADC. The ADC values are directly stored on to XRAM through on-chip DMA controller. Later, these stored values are processed by using quadrature sampling method to get amplitude and phase of the 100 waves. The amplitude and phase values of 100 waves are averaged to eliminate the random noise of the signal and are displayed on the LCD module. The amplitude and phase are sent to the PC through on-chip serial port (UART to store/plot the graph. The proposed lock-in amplifier is applied to study the phase transitions of sulfur sample by varying the temperature at slow rate (0.3 °C/min using microcontroller based temperature control system.

  3. Commonwealth Edison Company pressure locking test report

    Energy Technology Data Exchange (ETDEWEB)

    Bunte, B.D.; Kelly, J.F.

    1996-12-01

    Pressure Locking is a phenomena which can cause the unseating thrust for a gate valve to increase dramatically from its typical static unseating thrust. This can result in the valve actuator having insufficient capability to open the valve. In addition, this can result in valve damage in cases where the actuator capability exceeds the valve structural limits. For these reasons, a proper understanding of the conditions which may cause pressure locking and thermal binding, as well as a methodology for predicting the unseating thrust for a pressure locked or thermally bound valve, are necessary. This report discusses the primary mechanisms which cause pressure locking. These include sudden depressurization of piping adjacent to the valve and pressurization of fluid trapped in the valve bonnet due to heat transfer. This report provides a methodology for calculating the unseating thrust for a valve which is pressure locked. This report provides test data which demonstrates the accuracy of the calculation methodology.

  4. Commonwealth Edison Company pressure locking test report

    International Nuclear Information System (INIS)

    Bunte, B.D.; Kelly, J.F.

    1996-01-01

    Pressure Locking is a phenomena which can cause the unseating thrust for a gate valve to increase dramatically from its typical static unseating thrust. This can result in the valve actuator having insufficient capability to open the valve. In addition, this can result in valve damage in cases where the actuator capability exceeds the valve structural limits. For these reasons, a proper understanding of the conditions which may cause pressure locking and thermal binding, as well as a methodology for predicting the unseating thrust for a pressure locked or thermally bound valve, are necessary. This report discusses the primary mechanisms which cause pressure locking. These include sudden depressurization of piping adjacent to the valve and pressurization of fluid trapped in the valve bonnet due to heat transfer. This report provides a methodology for calculating the unseating thrust for a valve which is pressure locked. This report provides test data which demonstrates the accuracy of the calculation methodology

  5. Acoustic excitation of diffusion flames with coherent structure in a plane shear layer. ; Application of active combustion control to two-dimensional phase-locked arranging measurements. Soshiki kozo wo tomonau heimen sendai kakusan kaen no onkyo reiki. ; Nijigen iso heikin bunpu sokutei eno active nensho seigyo no oyo

    Energy Technology Data Exchange (ETDEWEB)

    Ishino, Y.; Kojima, T.; Oiwa, N.; Yamaguchi, S. (Nagoya Institute of Technology, Nagoya (Japan))

    1993-11-25

    The acoustic excitation of a plane diffusion flame enhances the periodicity of organized eddy controlled combustion. In this study, to clarify an effectiveness of application of active combustion control, phase characteristics of the excited eddy flames with high periodicity have been examined. A computer-aided phase-locked averaging method was employed to obtain graphical two-dimensional contour maps of the instantaneous profiles of temperature and CH emission. Both maps consisting of eight consecutive phases indicated clearly not only the periodic behavior of the organized eddy flame, but also the gas dynamic properties peculiar to those flames with coherent structure. In addition, the profiles of local contribution of the sound field to the combustion process were examined by calculating the two-dimensional distribution of the local Rayleigh index. Calculation results of the two-dimensional distribution of the local Rayleigh index indicated that the organized eddy flames have high sensitivity to sound, and play an important role in an interaction of sound and flame. 6 refs., 9 figs.

  6. Neglected locked vertical patellar dislocation

    Science.gov (United States)

    Gupta, Rakesh Kumar; Gupta, Vinay; Sangwan, Sukhbir Singh; Kamboj, Pradeep

    2012-01-01

    Patellar dislocations occurring about the vertical and horizontal axis are rare and irreducible. The neglected patellar dislocation is still rarer. We describe the clinical presentation and management of a case of neglected vertical patellar dislocation in a 6 year-old boy who sustained an external rotational strain with a laterally directed force to his knee. Initially the diagnosis was missed and 2 months later open reduction was done. The increased tension generated by the rotation of the lateral extensor retinaculum kept the patella locked in the lateral gutter even with the knee in full extension. Traumatic patellar dislocation with rotation around a vertical axis has been described earlier, but no such neglected case has been reported to the best of our knowledge. PMID:23162154

  7. Neglected locked vertical patellar dislocation

    Directory of Open Access Journals (Sweden)

    Rakesh Kumar Gupta

    2012-01-01

    Full Text Available Patellar dislocations occurring about the vertical and horizontal axis are rare and irreducible. The neglected patellar dislocation is still rarer. We describe the clinical presentation and management of a case of neglected vertical patellar dislocation in a 6 year-old boy who sustained an external rotational strain with a laterally directed force to his knee. Initially the diagnosis was missed and 2 months later open reduction was done. The increased tension generated by the rotation of the lateral extensor retinaculum kept the patella locked in the lateral gutter even with the knee in full extension. Traumatic patellar dislocation with rotation around a vertical axis has been described earlier, but no such neglected case has been reported to the best of our knowledge.

  8. Unusual Cause of Knee Locking

    Directory of Open Access Journals (Sweden)

    Gazi Huri

    2013-01-01

    Full Text Available We report a case of partial intrasubstance tear of popliteus tendon as an unusual cause of pseudolocking of the knee. A 13-year-old semiprofessional soccer player applied to our clinic with a locked right knee in spite of the therapy applied (cold pack, NSAID, and immobilization in another institution 20 days after the injury. Significant extension loss was observed in his right knee with 30∘–90∘ ROM. Magnetic resonance imaging (MRI and arthroscopy confirmed the intrasubstance tear of popliteus tendon and synovitis. The ruptured part of the tendon was debrided, and the inflammatory tissue around the tendon, which may lead to pseudolocking, was gently removed with a shaver in order to regain the normal ROM. The patient was discharged with full ROM and weight bearing first day after the surgery. To our knowledge, this is the first case demonstrating intrasubstance tear of popliteus tendon causing pseudolocking of the knee.

  9. Dispersive-cavity actively mode-locked fiber laser for stable radio frequency delivery

    International Nuclear Information System (INIS)

    Dai, Yitang; Wang, Ruixin; Yin, Feifei; Xu, Kun; Li, Jianqiang; Lin, Jintong

    2013-01-01

    We report a novel technique for highly stable transfer of a radio frequency (RF) comb over long optical fiber link, which is highly dispersive and is a part of an actively mode-locked fiber laser. Phase fluctuation along the fiber link, which is mainly induced by physical vibration and temperature fluctuations, is automatically compensated by the self-adapted wavelength shifting. Without phase-locking loop or any tunable parts, stable radio frequency is transferred over a 2-km fiber link, with a time jitter suppression ratio larger than 110. (letter)

  10. An innovative interpretation of rotating tearing mode locking to an external static current

    International Nuclear Information System (INIS)

    Coelho, R.; Lazzaro, E.

    2001-01-01

    Naturally occurring error fields in tokamaks, which arise from misalignments of the external field coils, may trigger the onset of tearing modes. The conditions under which a static error field is able to lock a rotating tearing mode and how this process takes place are discussed. The analysis presented contributes to a new understanding and interpretation of mode locking, given in terms of the superposition of a slipping layer (a radial layer of very fast mode phase variations) and the tearing layer, where reconnection takes place. In addition, a stabilizing operating window is found to exist, independent of the phase time evolution of the mode. (author). Letter-to-the-editor

  11. No Snowball on Habitable Tidally Locked Planets

    Science.gov (United States)

    Checlair, Jade; Menou, Kristen; Abbot, Dorian S.

    2017-08-01

    The TRAPPIST-1, Proxima Centauri, and LHS 1140 systems are the most exciting prospects for future follow-up observations of potentially inhabited planets. All of the planets orbit nearby M-stars and are likely tidally locked in 1:1 spin–orbit states, which motivates the consideration of the effects that tidal locking might have on planetary habitability. On Earth, periods of global glaciation (snowballs) may have been essential for habitability and remote signs of life (biosignatures) because they are correlated with increases in the complexity of life and in the atmospheric oxygen concentration. In this paper, we investigate the snowball bifurcation (sudden onset of global glaciation) on tidally locked planets using both an energy balance model and an intermediate-complexity global climate model. We show that tidally locked planets are unlikely to exhibit a snowball bifurcation as a direct result of the spatial pattern of insolation they receive. Instead, they will smoothly transition from partial to complete ice coverage and back. A major implication of this work is that tidally locked planets with an active carbon cycle should not be found in a snowball state. Moreover, this work implies that tidally locked planets near the outer edge of the habitable zone with low CO2 outgassing fluxes will equilibrate with a small unglaciated substellar region rather than cycling between warm and snowball states. More work is needed to determine how the lack of a snowball bifurcation might affect the development of life on a tidally locked planet.

  12. No Snowball on Habitable Tidally Locked Planets

    Energy Technology Data Exchange (ETDEWEB)

    Checlair, Jade; Abbot, Dorian S. [Department of the Geophysical Sciences, University of Chicago, 5734 South Ellis Avenue, Chicago, IL 60637 (United States); Menou, Kristen, E-mail: jadecheclair@uchicago.edu [Centre for Planetary Sciences, Department of Physical and Environmental Sciences, University of Toronto at Scarborough, Toronto, ON M1C 1A4 (Canada)

    2017-08-20

    The TRAPPIST-1, Proxima Centauri, and LHS 1140 systems are the most exciting prospects for future follow-up observations of potentially inhabited planets. All of the planets orbit nearby M-stars and are likely tidally locked in 1:1 spin–orbit states, which motivates the consideration of the effects that tidal locking might have on planetary habitability. On Earth, periods of global glaciation (snowballs) may have been essential for habitability and remote signs of life (biosignatures) because they are correlated with increases in the complexity of life and in the atmospheric oxygen concentration. In this paper, we investigate the snowball bifurcation (sudden onset of global glaciation) on tidally locked planets using both an energy balance model and an intermediate-complexity global climate model. We show that tidally locked planets are unlikely to exhibit a snowball bifurcation as a direct result of the spatial pattern of insolation they receive. Instead, they will smoothly transition from partial to complete ice coverage and back. A major implication of this work is that tidally locked planets with an active carbon cycle should not be found in a snowball state. Moreover, this work implies that tidally locked planets near the outer edge of the habitable zone with low CO{sub 2} outgassing fluxes will equilibrate with a small unglaciated substellar region rather than cycling between warm and snowball states. More work is needed to determine how the lack of a snowball bifurcation might affect the development of life on a tidally locked planet.

  13. No Snowball on Habitable Tidally Locked Planets

    International Nuclear Information System (INIS)

    Checlair, Jade; Abbot, Dorian S.; Menou, Kristen

    2017-01-01

    The TRAPPIST-1, Proxima Centauri, and LHS 1140 systems are the most exciting prospects for future follow-up observations of potentially inhabited planets. All of the planets orbit nearby M-stars and are likely tidally locked in 1:1 spin–orbit states, which motivates the consideration of the effects that tidal locking might have on planetary habitability. On Earth, periods of global glaciation (snowballs) may have been essential for habitability and remote signs of life (biosignatures) because they are correlated with increases in the complexity of life and in the atmospheric oxygen concentration. In this paper, we investigate the snowball bifurcation (sudden onset of global glaciation) on tidally locked planets using both an energy balance model and an intermediate-complexity global climate model. We show that tidally locked planets are unlikely to exhibit a snowball bifurcation as a direct result of the spatial pattern of insolation they receive. Instead, they will smoothly transition from partial to complete ice coverage and back. A major implication of this work is that tidally locked planets with an active carbon cycle should not be found in a snowball state. Moreover, this work implies that tidally locked planets near the outer edge of the habitable zone with low CO 2 outgassing fluxes will equilibrate with a small unglaciated substellar region rather than cycling between warm and snowball states. More work is needed to determine how the lack of a snowball bifurcation might affect the development of life on a tidally locked planet.

  14. Injection locking method for Raman beams in atom interferometer

    Science.gov (United States)

    Zi, Fei; Deng, Jianing; Zeng, Daji; Li, Tong; Sun, Mingli; Zhang, Xian; Huang, Kaikai; Lu, Xuanhui

    2018-03-01

    We present a novel method to generate two phase-locked beams with a frequency offset of 6.834 GHz. The output of the master laser is firstly modulated by an electric optical modulator (EOM), and then further injected into an Extended Cavity Diode Lasers (ECDL) which is used to filter out the unwanted mode and amplify the laser power. By locking to the first-order lower sideband of the modulated master laser, the average variance of the phase fluctuations is 5.6 x 10-3 rad2 , which implies phase coherence of 99.44% between the master laser and the slave ECDL. The line width of the beat notes is less than 1Hz. For the long term stability, with the delicate design of the electronic controller in ECDL, the phase coherence of the two laser beams can be stabilized over 200 hours without any adjustment. The Raman system is applicable for gravity detection with a preliminary sensitivity Δg/g of 4.5 x 10-7 for interrogation time of 1500 s.

  15. Correlations between locked modes and impurity influxes

    Energy Technology Data Exchange (ETDEWEB)

    Fishpool, G M [Commission of the European Communities, Abingdon (United Kingdom). JET Joint Undertaking; Lawson, K D [UKAEA Culham Lab., Abingdon (United Kingdom)

    1994-07-01

    An analysis of pulses that were disturbed by medium Z impurity influxes (Cl, Cr, Fe and Ni) recorded during the 91/92 JET operations, has demonstrated that such influxes can result in MHD modes which subsequently ``lock``. A correlation is found between the power radiated by the influx and the time difference between the start of the influx and the beginning of the locked mode. The growth in the amplitude of the locked mode itself can lead to further impurity influxes. A correlation is noted between intense influxes (superior to 10 MW) and the mode ``unlocking``. (authors). 4 refs., 4 figs.

  16. The Advanced Thread-Locking Mechanism

    Science.gov (United States)

    Weiss, Wolfgang

    2005-12-01

    Locking of threaded members is accomplished by a wide variety of engineering solutions. Generally, in terms of separate locking devices or by built-in locking features such as friction generating means.In regard of space flight vehicles, threaded joints are subject to severe vibration loads during launch, maneuvering, and reentry. This requires fastening systems which are capable to join structural members and attach accessories or equipment in a secure manner. However, manned spacecraft and especially payload components will be subject to installation activity during orbital or interstellar flight maintenance, repair, or mission modification. This, in turn, requires fast separation and engaging of the concerned fasteners, yet providing performance characteristics for high reliable and safe joints.The further described Advanced Thread Locking Mechanism (ATLM) has been developed to combine the merits of both, safe joining technique and a fast installation process. The ATLM uses a freewheel which is securely installed in one part of the threaded member and releasable coupled with the engaged counterpart. While screwing the threaded members together, once coupled, the freewheel will allow free mating of the threaded members including torquing to the desired value. The moment, the pair of threaded fasteners is forced to unscrew (by intended or unintended occurrence of torque in the undoing direction) the freewheel does lock instantly. Disengaging the coupling between the members of the threaded joint takes a separate release action.Owing to the nature of the ATLM, there are a number of design variants ready for implementation.Threaded fasteners in ATLM design are highly recommended for mechanical joints subject to fastening and unfastening during Extra Vehicular Activity (EVA) in course of space flight operations. This is justified through:1. Threaded members mate free running, thus, torque values preset at the wrenching tool are not influenced by varying prevailing

  17. Single-ion quantum lock-in amplifier.

    Science.gov (United States)

    Kotler, Shlomi; Akerman, Nitzan; Glickman, Yinnon; Keselman, Anna; Ozeri, Roee

    2011-05-05

    Quantum metrology uses tools from quantum information science to improve measurement signal-to-noise ratios. The challenge is to increase sensitivity while reducing susceptibility to noise, tasks that are often in conflict. Lock-in measurement is a detection scheme designed to overcome this difficulty by spectrally separating signal from noise. Here we report on the implementation of a quantum analogue to the classical lock-in amplifier. All the lock-in operations--modulation, detection and mixing--are performed through the application of non-commuting quantum operators to the electronic spin state of a single, trapped Sr(+) ion. We significantly increase its sensitivity to external fields while extending phase coherence by three orders of magnitude, to more than one second. Using this technique, we measure frequency shifts with a sensitivity of 0.42 Hz Hz(-1/2) (corresponding to a magnetic field measurement sensitivity of 15 pT Hz(-1/2)), obtaining an uncertainty of less than 10 mHz (350 fT) after 3,720 seconds of averaging. These sensitivities are limited by quantum projection noise and improve on other single-spin probe technologies by two orders of magnitude. Our reported sensitivity is sufficient for the measurement of parity non-conservation, as well as the detection of the magnetic field of a single electronic spin one micrometre from an ion detector with nanometre resolution. As a first application, we perform light shift spectroscopy of a narrow optical quadrupole transition. Finally, we emphasize that the quantum lock-in technique is generic and can potentially enhance the sensitivity of any quantum sensor. ©2011 Macmillan Publishers Limited. All rights reserved

  18. Passive mode-locking dynamics in a 3.1GHz quantum dot laser diode operating around 1.5μm

    NARCIS (Netherlands)

    Tahvili, M.S.; Heck, M.J.R.; Nötzel, R.; Smit, M.K.; Bente, E.A.J.M.

    2010-01-01

    We report on passive mode-locking in a 3.1GHz InAs/InP(100) quantum dot laser diode operating around 1.5µm. The range of stable passive mode-locking, detailed measurements of the linewidth of the optical modes and the phase modulation in output pulses are presented.

  19. Arm locking with Doppler estimation errors

    Energy Technology Data Exchange (ETDEWEB)

    Yu Yinan; Wand, Vinzenz; Mitryk, Shawn; Mueller, Guido, E-mail: yinan@phys.ufl.ed [Department of Physics, University of Florida, Gainesville, FL 32611 (United States)

    2010-05-01

    At the University of Florida we developed the University of Florida LISA Interferometer Simulator (UFLIS) in order to study LISA interferometry with hardware in the loop at a system level. One of the proposed laser frequency stabilization techniques in LISA is arm locking. Arm locking uses an adequately filtered linear combination of the LISA arm signals as a frequency reference. We will report about experiments in which we demonstrated arm locking using UFLIS. During these experiments we also discovered a problem associated with the Doppler shift of the return beam. The initial arm locking publications assumed that this Doppler shift can perfectly be subtracted inside the phasemeter or adds an insignificant offset to the sensor signal. However, the remaining Doppler knowledge error will cause a constant change in the laser frequency if unaccounted for. Several ways to circumvent this problem have been identified. We performed detailed simulations and started preliminary experiments to verify the performance of the proposed new controller designs.

  20. Improving generalized inverted index lock wait times

    Science.gov (United States)

    Borodin, A.; Mirvoda, S.; Porshnev, S.; Ponomareva, O.

    2018-01-01

    Concurrent operations on tree like data structures is a cornerstone of any database system. Concurrent operations intended for improving read\\write performance and usually implemented via some way of locking. Deadlock-free methods of concurrency control are known as tree locking protocols. These protocols provide basic operations(verbs) and algorithm (ways of operation invocations) for applying it to any tree-like data structure. These algorithms operate on data, managed by storage engine which are very different among RDBMS implementations. In this paper, we discuss tree locking protocol implementation for General inverted index (Gin) applied to multiversion concurrency control (MVCC) storage engine inside PostgreSQL RDBMS. After that we introduce improvements to locking protocol and provide usage statistics about evaluation of our improvement in very high load environment in one of the world’s largest IT company.

  1. Interband optical pulse injection locking of quantum dot mode-locked semiconductor laser.

    Science.gov (United States)

    Kim, Jimyung; Delfyett, Peter J

    2008-07-21

    We experimentally demonstrate optical clock recovery from quantum dot mode-locked semiconductor lasers by interband optical pulse injection locking. The passively mode-locked slave laser oscillating on the ground state or the first excited state transition is locked through the injection of optical pulses generated via the opposite transition bands, i.e. the first excited state or the ground state transition from the hybridly mode-locked master laser, respectively. When an optical pulse train generated via the first excited state from the master laser is injected to the slave laser oscillating via ground state, the slave laser shows an asymmetric locking bandwidth around the nominal repetition rate of the slave laser. In the reverse injection case of, i.e. the ground state (master laser) to the first excited state (slave laser), the slave laser does not lock even though both lasers oscillate at the same cavity frequency. In this case, the slave laser only locks to higher injection rates as compared to its own nominal repetition rate, and also shows a large locking bandwidth of 6.7 MHz.

  2. Bouncy knee in a semi-automatic knee lock prosthesis.

    Science.gov (United States)

    Fisher, L D; Lord, M

    1986-04-01

    The Bouncy Knee concept has previously proved of value when fitted to stabilised knee units of active amputees. The stance phase flex-extend action afforded by a Bouncy Knee increased the symmetry of gait and also gave better tolerance to slopes and uneven ground. A bouncy function has now been incorporated into a knee of the semi-automatic knee lock design in a pilot laboratory trial involving six patients. These less active patients did not show consistent changes in symmetry of gait, but demonstrated an improved ability to walk on slopes and increased their walking range. Subjective response was positive, as noted in the previous trials.

  3. Development of wavelength locking circuit for 1.53 micron water vapor monitoring coherent differential absorption LIDAR

    Science.gov (United States)

    Imaki, Masaharu; Kojima, Ryota; Kameyama, Shumpei

    2018-04-01

    We have studied a ground based coherent differential absorption LIDAR (DIAL) for vertical profiling of water vapor density using a 1.5μm laser wavelength. A coherent LIDAR has an advantage in daytime measurement compared with incoherent LIDAR because the influence of background light is greatly suppressed. In addition, the LIDAR can simultaneously measure wind speed and water vapor density. We had developed a wavelength locking circuit using the phase modulation technique and offset locking technique, and wavelength stabilities of 0.123 pm which corresponds to 16 MHz are realized. In this paper, we report the wavelength locking circuits for the 1.5 um wavelength.

  4. Automatic locking orthotic knee device

    Science.gov (United States)

    Weddendorf, Bruce C. (Inventor)

    1993-01-01

    An articulated tang in clevis joint for incorporation in newly manufactured conventional strap-on orthotic knee devices or for replacing such joints in conventional strap-on orthotic knee devices is discussed. The instant tang in clevis joint allows the user the freedom to extend and bend the knee normally when no load (weight) is applied to the knee and to automatically lock the knee when the user transfers weight to the knee, thus preventing a damaged knee from bending uncontrollably when weight is applied to the knee. The tang in clevis joint of the present invention includes first and second clevis plates, a tang assembly and a spacer plate secured between the clevis plates. Each clevis plate includes a bevelled serrated upper section. A bevelled shoe is secured to the tank in close proximity to the bevelled serrated upper section of the clevis plates. A coiled spring mounted within an oblong bore of the tang normally urges the shoes secured to the tang out of engagement with the serrated upper section of each clevic plate to allow rotation of the tang relative to the clevis plate. When weight is applied to the joint, the load compresses the coiled spring, the serrations on each clevis plate dig into the bevelled shoes secured to the tang to prevent relative movement between the tang and clevis plates. A shoulder is provided on the tang and the spacer plate to prevent overextension of the joint.

  5. Kuramoto model with uniformly spaced frequencies: Finite-N asymptotics of the locking threshold.

    Science.gov (United States)

    Ottino-Löffler, Bertrand; Strogatz, Steven H

    2016-06-01

    We study phase locking in the Kuramoto model of coupled oscillators in the special case where the number of oscillators, N, is large but finite, and the oscillators' natural frequencies are evenly spaced on a given interval. In this case, stable phase-locked solutions are known to exist if and only if the frequency interval is narrower than a certain critical width, called the locking threshold. For infinite N, the exact value of the locking threshold was calculated 30 years ago; however, the leading corrections to it for finite N have remained unsolved analytically. Here we derive an asymptotic formula for the locking threshold when N≫1. The leading correction to the infinite-N result scales like either N^{-3/2} or N^{-1}, depending on whether the frequencies are evenly spaced according to a midpoint rule or an end-point rule. These scaling laws agree with numerical results obtained by Pazó [D. Pazó, Phys. Rev. E 72, 046211 (2005)PLEEE81539-375510.1103/PhysRevE.72.046211]. Moreover, our analysis yields the exact prefactors in the scaling laws, which also match the numerics.

  6. Theta oscillations locked to intended actions rhythmically modulate perception.

    Science.gov (United States)

    Tomassini, Alice; Ambrogioni, Luca; Medendorp, W Pieter; Maris, Eric

    2017-07-07

    Ongoing brain oscillations are known to influence perception, and to be reset by exogenous stimulations. Voluntary action is also accompanied by prominent rhythmic activity, and recent behavioral evidence suggests that this might be coupled with perception. Here, we reveal the neurophysiological underpinnings of this sensorimotor coupling in humans. We link the trial-by-trial dynamics of EEG oscillatory activity during movement preparation to the corresponding dynamics in perception, for two unrelated visual and motor tasks. The phase of theta oscillations (~4 Hz) predicts perceptual performance, even >1 s before movement. Moreover, theta oscillations are phase-locked to the onset of the movement. Remarkably, the alignment of theta phase and its perceptual relevance unfold with similar non-monotonic profiles, suggesting their relatedness. The present work shows that perception and movement initiation are automatically synchronized since the early stages of motor planning through neuronal oscillatory activity in the theta range.

  7. Detecting phase synchronization between coupled non-phase-coherent oscillators

    International Nuclear Information System (INIS)

    Follmann, Rosangela; Macau, Elbert E.N.; Rosa, Epaminondas

    2009-01-01

    We compare two methods for detecting phase synchronization in coupled non-phase-coherent oscillators. One method is based on the locking of self-sustained oscillators with an irregular signal. The other uses trajectory recurrences in phase space. We identify the pros and cons of both methods and propose guidelines to detect phase synchronization in data series.

  8. Spin polarization versus color–flavor locking in high-density quark matter

    DEFF Research Database (Denmark)

    Tsue, Yasuhiko; da Providência, João; Providência, Constança

    2015-01-01

    It is shown that spin polarization with respect to each flavor in three-flavor quark matter occurs instead of color–flavor locking at high baryon density by using the Nambu–Jona-Lasinio model with four-point tensor-type interaction. Also, it is indicated that the order of phase transition between...

  9. A novel optimised and validated method for analysis of multi-residues of pesticides in fruits and vegetables by microwave-assisted extraction (MAE)-dispersive solid-phase extraction (d-SPE)-retention time locked (RTL)-gas chromatography-mass spectrometry with Deconvolution reporting software (DRS).

    Science.gov (United States)

    Satpathy, Gouri; Tyagi, Yogesh Kumar; Gupta, Rajinder Kumar

    2011-08-01

    A rapid, effective and ecofriendly method for sensitive screening and quantification of 72 pesticides residue in fruits and vegetables, by microwave-assisted extraction (MAE) followed by dispersive solid-phase extraction (d-SPE), retention time locked (RTL) capillary gas-chromatographic separation in trace ion mode mass spectrometric determination has been validated as per ISO/IEC: 17025:2005. Identification and reporting with total and extracted ion chromatograms were facilitated to a great extent by Deconvolution reporting software (DRS). For all compounds LOD were 0.002-0.02mg/kg and LOQ were 0.025-0.100mg/kg. Correlation coefficients of the calibration curves in the range of 0.025-0.50mg/kg were >0.993. To validate matrix effects repeatability, reproducibility, recovery and overall uncertainty were calculated for the 35 matrices at 0.025, 0.050 and 0.100mg/kg. Recovery ranged between 72% and 114% with RSD of <20% for repeatability and intermediate precision. The reproducibility of the method was evaluated by an inter laboratory participation and Z score obtained within ±2. Copyright © 2011 Elsevier Ltd. All rights reserved.

  10. EQUATORIAL SUPERROTATION ON TIDALLY LOCKED EXOPLANETS

    International Nuclear Information System (INIS)

    Showman, Adam P.; Polvani, Lorenzo M.

    2011-01-01

    The increasing richness of exoplanet observations has motivated a variety of three-dimensional (3D) atmospheric circulation models of these planets. Under strongly irradiated conditions, models of tidally locked, short-period planets (both hot Jupiters and terrestrial planets) tend to exhibit a circulation dominated by a fast eastward, or 'superrotating', jet stream at the equator. When the radiative and advection timescales are comparable, this phenomenon can cause the hottest regions to be displaced eastward from the substellar point by tens of degrees longitude. Such an offset has been subsequently observed on HD 189733b, supporting the possibility of equatorial jets on short-period exoplanets. Despite its relevance, however, the dynamical mechanisms responsible for generating the equatorial superrotation in such models have not been identified. Here, we show that the equatorial jet results from the interaction of the mean flow with standing Rossby waves induced by the day-night thermal forcing. The strong longitudinal variations in radiative heating-namely intense dayside heating and nightside cooling-trigger the formation of standing, planetary-scale equatorial Rossby and Kelvin waves. The Rossby waves develop phase tilts that pump eastward momentum from high latitudes to the equator, thereby inducing equatorial superrotation. We present an analytic theory demonstrating this mechanism and explore its properties in a hierarchy of one-layer (shallow-water) calculations and fully 3D models. The wave-mean-flow interaction produces an equatorial jet whose latitudinal width is comparable to that of the Rossby waves, namely the equatorial Rossby deformation radius modified by radiative and frictional effects. For conditions typical of synchronously rotating hot Jupiters, this length is comparable to a planetary radius, explaining the broad scale of the equatorial jet obtained in most hot-Jupiter models. Our theory illuminates the dependence of the equatorial jet

  11. Locked magnetic island chains in toroidally flow damped tokamak plasmas

    International Nuclear Information System (INIS)

    Fitzpatrick, R; Waelbroeck, F L

    2010-01-01

    The physics of a locked magnetic island chain maintained in the pedestal of an H-mode tokamak plasma by a static, externally generated, multi-harmonic, helical magnetic perturbation is investigated. The non-resonant harmonics of the external perturbation are assumed to give rise to significant toroidal flow damping in the pedestal, in addition to the naturally occurring poloidal flow damping. Furthermore, the flow damping is assumed to be sufficiently strong to relax the pedestal ion toroidal and poloidal fluid velocities to fixed values determined by neoclassical theory. The resulting neoclassical ion flow causes a helical phase-shift to develop between the locked island chain and the resonant harmonic of the external perturbation. Furthermore, when this phase-shift exceeds a critical value, the chain unlocks from the resonant harmonic and starts to rotate, after which it decays away and is replaced by a helical current sheet. The neoclassical flow also generates an ion polarization current in the vicinity of the island chain which either increases or decreases the chain's radial width, depending on the direction of the flow. If the polarization effect is stabilizing, and exceeds a critical amplitude, then the helical island equilibrium becomes unstable, and the chain again decays away. The critical amplitude of the resonant harmonic of the external perturbation at which the island chain either unlocks or becomes unstable is calculated as a function of the pedestal ion pressure, the neoclassical poloidal and toroidal ion velocities and the poloidal and toroidal flow damping rates.

  12. A Wide Lock-Range Referenceless CDR with Automatic Frequency Acquisition

    OpenAIRE

    Seon-Kyoo Lee; Young-Sang Kim; Hong-June Park; Jae-Yoon Sim

    2011-01-01

    A wide lock-range referenceless CDR circuit is proposed with an automatic tracking of data rate. For efficient frequency acquisition, a DLL-based loop is used with a simple phase/frequency detector to extract 1-bit period of input data stream. The CDR, implemented in a 65 nm CMOS, shows a lock range of 650 Mb/s-to-8 Gb/s and BER of less than 10-12 at 8 Gb/s with low power consumption.

  13. A Wide Lock-Range Referenceless CDR with Automatic Frequency Acquisition

    Directory of Open Access Journals (Sweden)

    Seon-Kyoo Lee

    2011-01-01

    Full Text Available A wide lock-range referenceless CDR circuit is proposed with an automatic tracking of data rate. For efficient frequency acquisition, a DLL-based loop is used with a simple phase/frequency detector to extract 1-bit period of input data stream. The CDR, implemented in a 65 nm CMOS, shows a lock range of 650 Mb/s-to-8 Gb/s and BER of less than 10-12 at 8 Gb/s with low power consumption.

  14. Control of fibre laser mode-locking by narrow-band Bragg gratings

    International Nuclear Information System (INIS)

    Laegsgaard, J

    2008-01-01

    The use of narrow-band high-reflectivity fibre Bragg gratings (FBGs) as end mirrors in a fibre laser cavity with passive mode-locking provided by a semiconductor saturable absorber mirror (SESAM) is investigated numerically. The FBG is found to control the energy range of stable mode-locking, which may be shifted far outside the regime of SESAM saturation by a suitable choice of FBG and cavity length. The pulse shape is controlled by the combined effects of FBG dispersion and self-phase modulation in the fibres, and a few ps pulses can be obtained with standard uniform FBGs

  15. Properties of color-flavor locked strange quark matter in an external strong magnetic field

    Institute of Scientific and Technical Information of China (English)

    崔帅帅; 彭光雄; 陆振烟; 彭程; 徐建峰

    2015-01-01

    The properties of color-flavor locked strange quark matter in an external strong magnetic field are investigated in a quark model with density-dependent quark masses. Parameters are determined by stability arguments. It is found that the minimum energy per baryon of the color-flavor locked (MCFL) matter decreases with increasing magnetic-field strength in a certain range, which makes MCFL matter more stable than other phases within a proper magnitude of the external magnetic field. However, if the energy of the field itself is added, the total energy per baryon will increase.

  16. Universal spin-momentum locked optical forces

    Energy Technology Data Exchange (ETDEWEB)

    Kalhor, Farid [Department of Electrical and Computer Engineering, University of Alberta, Edmonton, Alberta T6G 1H9 (Canada); Thundat, Thomas [Department of Chemical and Materials Engineering, University of Alberta, Edmonton, Alberta T6G 1H9 (Canada); Jacob, Zubin, E-mail: zjacob@purdue.edu [Department of Electrical and Computer Engineering, University of Alberta, Edmonton, Alberta T6G 1H9 (Canada); Birck Nanotechnology Center, Department of Electrical and Computer Engineering, Purdue University, West Lafayette, Indiana 47906 (United States)

    2016-02-08

    Evanescent electromagnetic waves possess spin-momentum locking, where the direction of propagation (momentum) is locked to the inherent polarization of the wave (transverse spin). We study the optical forces arising from this universal phenomenon and show that the fundamental origin of recently reported non-trivial optical chiral forces is spin-momentum locking. For evanescent waves, we show that the direction of energy flow, the direction of decay, and the direction of spin follow a right hand rule for three different cases of total internal reflection, surface plasmon polaritons, and HE{sub 11} mode of an optical fiber. Furthermore, we explain how the recently reported phenomena of lateral optical force on chiral and achiral particles are caused by the transverse spin of the evanescent field and the spin-momentum locking phenomenon. Finally, we propose an experiment to identify the unique lateral forces arising from the transverse spin in the optical fiber and point to fundamental differences of the spin density from the well-known orbital angular momentum of light. Our work presents a unified view on spin-momentum locking and how it affects optical forces on chiral and achiral particles.

  17. A novel mode-locking technique

    International Nuclear Information System (INIS)

    Chen Shaoh; Chen Youming; Chen Taolue; Si Xiangdong; Yang Yi; Deng Ximing

    1993-01-01

    A novel mode-locked Nd:YAG oscillator has been developed by using an ultrafast photoconductive feedback controlled loop, and mode-locked pulses with a duration of 100ps have been obtained. The energy instability of the pulse trains is ±5%. In this type of mode-locking technology, a type of deep-level doped GaAs (Cr-doped) photoconductive switch, which has a fast response in time and is free of avalance process, is used to drive a Pockels' cell to realize mode-locking. The dark resistance of this type of photoconductive switch is 6 orders of magnitude higher than that of the intrinsic single-crystal silicon, and it can reach a level as high as 10 9 ohms. Consequently, it is able to withstand longterm operation at several thousand DC volts. By means of the photoconductive ohmic switch characteristics, the authors have designed a positive feedback control network which has a very fast response time, and can couple a voltage of up to a thousand volts. Using this unit in a Nd:YAG laser, they have successfully realized a very stable mode-locked pulse train with pulse width shorter than 100 ps. The operation principle, and the results of the preliminary experiments are presented here. 1 ref., 3 figs

  18. Laser lock-in thermography for thermal contact characterisation of surface layer

    International Nuclear Information System (INIS)

    Semerok, A.; Jaubert, F.; Fomichev, S.V.; Thro, P.-Y.; Courtois, X.; Grisolia, C.

    2012-01-01

    Lock-in thermography was applied to determine the thermal contact conductance of a W-layer (140 μm) on a CFC-substrate. A lock-in thermography system together with a pulse repetition rate Nd:YAG laser (1064 nm, 1–500 Hz pulse repetition rate) for layer heating was applied for phase shift measurements on the W-layer. A numerical model for direct phase shift calculations was developed and applied to rapid determination of the Fourier amplitudes and phases of the temperature. Thermal conductance coefficients were obtained by comparing the experimental and simulation phase shifts. -- Highlights: ► Lock-in thermography determines a layer/substrate thermal conductance. ► Thermal conductance coefficient of W-layer on a CFC-substrate. ► Model for direct phase shift calculations was developed and applied. ► Rapid determination of the Fourier amplitudes and phases of the temperature. ► Comparing the experimental and simulation phase shifts.

  19. Hersendood. Mackies leibniziaanse herinterpretatie van Lockes theorie van persoonsidentiteit

    OpenAIRE

    De Vleeschouwer, Gregory

    2009-01-01

    In his book, 'Problems from Locke', John Leslie Mackie presents a theory of personal identity (pi) that is meant to be a supplement and correction of Locke's pi-theory. In a first part I introduce the criterion of pi that was standard before Locke's pi-theory. By showing in a second part how Locke reacted against this traditional criterion, I show wherein the singularity of Locke's pi-theory exists. In a third part I explain how Leibniz is moved by the same solicitude as Locke, but also how h...

  20. Lock threshold deterioration induced by antenna vibration and signal coupling effects in hypersonic vehicle carrier tracking system of Ka band

    Directory of Open Access Journals (Sweden)

    Congying ZHU

    2018-04-01

    Full Text Available The envelope of a hypersonic vehicle is affected by severe fluctuating pressure, which causes the airborne antenna to vibrate slightly. This vibration mixes with the transmitted signals and thus introduces additional multiplicative phase noise. Antenna vibration and signal coupling effects as well as their influence on the lock threshold of the hypersonic vehicle carrier tracking system of the Ka band are investigated in this study. A vibration model is initially established to obtain phase noise in consideration of the inherent relationship between vibration displacement and electromagnetic wavelength. An analytical model of the Phase-Locked Loop (PLL, which is widely used in carrier tracking systems, is established. The coupling effects on carrier tracking performance are investigated and quantitatively analyzed by imposing the multiplicative phase noise on the PLL model. Simulation results show that the phase noise presents a Gaussian distribution and is similar to vibration displacement variation. A large standard deviation in vibration displacement exerts a significant effect on the lock threshold. A critical standard deviation is observed in the PLL of Binary Phase Shift Keying (BPSK and Quadrature Phase Shift Keying (QPSK signals. The effect on QPSK signals is more severe than that on BPSK signals. The maximum tolerable standard deviations normalized by the wavelength of the carrier are 0.04 and 0.02 for BPSK and QPSK signals, respectively. With these critical standard deviations, lock thresholds are increased from −12 and −4 dB to 3 and −2 dB, respectively. Keywords: Antenna vibration, Carrier tracking performance, Lock threshold, Phase locked loop, Tracking Telemetry and Command (TT&C signals

  1. Mode-locking in an infinite set of coupled circle maps

    International Nuclear Information System (INIS)

    Alstroem, P.; Ritala, R.K.

    1986-06-01

    We show that the mode-locking in coupled circle maps with random phases is very different from that in a single circle map. A finite nonlinearity K c is needed for a step to appear. The width of the step behaves as (K-K c ) 2 . The complete mode-locking (at K=1 for uncoupled maps) behaves singularly as the coupling is turned on. We argue that our model describes the mode-locking in charge-density-wave materials. Our results are in qualitative agreement with experimental observations by Sherwin and Zettl that only few true steps exist in I-V characteristics and that in addition to these there are some 'incomplete' steps. (orig.)

  2. Analysis of synchronized regimes for injection-locked spin-transfer nano-oscillators

    Energy Technology Data Exchange (ETDEWEB)

    D' Aquino, M., E-mail: daquino@uniparthenope.it [Department of Technology, University of Napoli ' Parthenope' , 80143 Napoli (Italy); Serpico, C. [Department of Engineering, University of Napoli Federico II, 80125 Napoli (Italy); Bonin, R. [Politecnico di Torino - Sede di Verres, 11029 Verres (Aosta) (Italy); Bertotti, G. [Istituto Nazionale di Ricerca Metrologica, 10135 Torino (Italy); Mayergoyz, I.D. [ECE Dept. and UMIACS, University of Maryland, College Park, MD 20742 (United States)

    2012-05-01

    The large-angle magnetization dynamics of an injection-locked spin-transfer nano-oscillator (STNO) is studied. The magnetic system is subject to the action of time-varying spin-polarized currents and external magnetic fields. The uniform mode theory is developed and describes the hysteretic synchronization mechanism in terms of bifurcations of equilibria and limit cycles of appropriate dynamical systems. Analytical predictions of control parameters for the synchronization between the magnetization self-oscillation and the external microwave excitations (current, field) are provided. The effect of temperature on the locking band and the hysteretic character of the oscillation response is analyzed. An analytical approach is developed to determine the thermally induced sidebands in the power spectral density of phase-locked oscillations as a function of control parameters. The analytical predictions are in good agreement with the results of numerical simulations.

  3. Quantum dash based single section mode locked lasers for photonic integrated circuits.

    Science.gov (United States)

    Joshi, Siddharth; Calò, Cosimo; Chimot, Nicolas; Radziunas, Mindaugas; Arkhipov, Rostislav; Barbet, Sophie; Accard, Alain; Ramdane, Abderrahim; Lelarge, Francois

    2014-05-05

    We present the first demonstration of an InAs/InP Quantum Dash based single-section frequency comb generator designed for use in photonic integrated circuits (PICs). The laser cavity is closed using a specifically designed Bragg reflector without compromising the mode-locking performance of the self pulsating laser. This enables the integration of single-section mode-locked laser in photonic integrated circuits as on-chip frequency comb generators. We also investigate the relations between cavity modes in such a device and demonstrate how the dispersion of the complex mode frequencies induced by the Bragg grating implies a violation of the equi-distance between the adjacent mode frequencies and, therefore, forbids the locking of the modes in a classical Bragg Device. Finally we integrate such a Bragg Mirror based laser with Semiconductor Optical Amplifier (SOA) to demonstrate the monolithic integration of QDash based low phase noise sources in PICs.

  4. Active mode-locking of mid-infrared quantum cascade lasers with short gain recovery time.

    Science.gov (United States)

    Wang, Yongrui; Belyanin, Alexey

    2015-02-23

    We investigate the dynamics of actively modulated mid-infrared quantum cascade lasers (QCLs) using space- and time-domain simulations of coupled density matrix and Maxwell equations with resonant tunneling current taken into account. We show that it is possible to achieve active mode locking and stable generation of picosecond pulses in high performance QCLs with a vertical laser transition and a short gain recovery time by bias modulation of a short section of a monolithic Fabry-Perot cavity. In fact, active mode locking in QCLs with a short gain recovery time turns out to be more robust to the variation of parameters as compared to previously studied lasers with a long gain recovery time. We investigate the effects of spatial hole burning and phase locking on the laser output.

  5. Wideband laser locking to an atomic reference with modulation transfer spectroscopy.

    Science.gov (United States)

    Negnevitsky, V; Turner, L D

    2013-02-11

    We demonstrate that conventional modulated spectroscopy apparatus, used for laser frequency stabilization in many atomic physics laboratories, can be enhanced to provide a wideband lock delivering deep suppression of frequency noise across the acoustic range. Using an acousto-optic modulator driven with an agile oscillator, we show that wideband frequency modulation of the pump laser in modulation transfer spectroscopy produces the unique single lock-point spectrum previously demonstrated with electro-optic phase modulation. We achieve a laser lock with 100 kHz feedback bandwidth, limited by our laser control electronics. This bandwidth is sufficient to reduce frequency noise by 30 dB across the acoustic range and narrows the imputed linewidth by a factor of five.

  6. A simplified digital lock-in amplifier for the scanning grating spectrometer.

    Science.gov (United States)

    Wang, Jingru; Wang, Zhihong; Ji, Xufei; Liu, Jie; Liu, Guangda

    2017-02-01

    For the common measurement and control system of a scanning grating spectrometer, the use of an analog lock-in amplifier requires complex circuitry and sophisticated debugging, whereas the use of a digital lock-in amplifier places a high demand on the calculation capability and storage space. In this paper, a simplified digital lock-in amplifier based on averaging the absolute values within a complete period is presented and applied to a scanning grating spectrometer. The simplified digital lock-in amplifier was implemented on a low-cost microcontroller without multipliers, and got rid of the reference signal and specific configuration of the sampling frequency. Two positive zero-crossing detections were used to lock the phase of the measured signal. However, measurement method errors were introduced by the following factors: frequency fluctuation, sampling interval, and integer restriction of the sampling number. The theoretical calculation and experimental results of the signal-to-noise ratio of the proposed measurement method were 2055 and 2403, respectively.

  7. Discretely tunable micromachined injection-locked lasers

    International Nuclear Information System (INIS)

    Cai, H; Yu, M B; Lo, G Q; Kwong, D L; Zhang, X M; Liu, A Q; Liu, B

    2010-01-01

    This paper reports a micromachined injection-locked laser (ILL) to provide tunable discrete wavelengths. It utilizes a non-continuously tunable laser as the master to lock a Fabry–Pérot semiconductor laser chip. Both lasers are integrated into a deep-etched silicon chip with dimensions of 3 mm × 3 mm × 0.8 mm. Based on the experimental results, significant improvements in the optical power and spectral purity have been achieved in the fully locked state, and optical hysteresis and bistability have also been observed in response to the changes of the output wavelength and optical power of the master laser. As a whole system, the micromachined ILL is able to provide single mode, discrete wavelength tuning, high power and direct modulation with small size and single-chip solution, making it promising for advanced optical communications such as wavelength division multiplexing optical access networks.

  8. Using river locks to teach hydrodynamic concepts

    Science.gov (United States)

    Carvalho-Santos, Vagson L.; Mendes, Thales C.; Silva, Enisvaldo C.; Rios, Márcio L.; Silva, Anderson A. P.

    2013-11-01

    In this work, the use of a river lock as a non-formal setting for teaching hydrodynamical concepts is proposed. In particular, we describe the operation of a river lock situated at the Sobradinho dam, on the São Francisco River (Brazil). A model to represent and to analyse the dynamics of river lock operation is presented and we derive the dynamical equations for the rising of the water column as an example to understand the Euler equation. Furthermore, with this activity, we enable the integration of content initially introduced in the classroom with practical applications, thereby allowing the association of physical themes to content relevant in disciplines such as history and geography. In addition, experiences of this kind enable teachers to talk about the environmental and social impacts caused by the construction of a dam and, consequently, a crossover of concepts has been made possible, leading to more meaningful learning for the students.

  9. Using river locks to teach hydrodynamic concepts

    International Nuclear Information System (INIS)

    Carvalho-Santos, Vagson L; Mendes, Thales C; Silva, Enisvaldo C; Rios, Márcio L; Silva, Anderson A P

    2013-01-01

    In this work, the use of a river lock as a non-formal setting for teaching hydrodynamical concepts is proposed. In particular, we describe the operation of a river lock situated at the Sobradinho dam, on the São Francisco River (Brazil). A model to represent and to analyse the dynamics of river lock operation is presented and we derive the dynamical equations for the rising of the water column as an example to understand the Euler equation. Furthermore, with this activity, we enable the integration of content initially introduced in the classroom with practical applications, thereby allowing the association of physical themes to content relevant in disciplines such as history and geography. In addition, experiences of this kind enable teachers to talk about the environmental and social impacts caused by the construction of a dam and, consequently, a crossover of concepts has been made possible, leading to more meaningful learning for the students. (paper)

  10. John Locke and the right to resistance

    Directory of Open Access Journals (Sweden)

    Jovanov Ilija D.

    2015-01-01

    Full Text Available John Locke was a great thinker and many works have been devoted to clear up his theories. One of the most significant, stated in his principal work, Two Treatises of Government, is the theory of the right to resistance. It was a bit revolutionary then, and to a large extent it is today. Domination of legal positivism is negation of that, by Locke, natural right. However, the fact is that in recent times the resistance to the established power occurs in a number of countries and in different forms, so that the idea of the right to resistance becomes live question again. In this regard it is interesting to consider Locke's viewpoint on this important issue and to determine whether his theory on the resistance is applicable in modern societies.

  11. Locking Lasers to RF in an Ultrafast FEL

    International Nuclear Information System (INIS)

    Wilcox, R.; Huang, G.; Doolittle, L.; White, W.; Frisch, J.; Coffee, R.

    2010-01-01

    Using a novel, phase-stabilized RF-over-fiber scheme, they transmit 3GHz over 300m with 27fs RMS error in 250kHz bandwidth over 12 hours, and phase lock a laser to enable ultrafast pump-probe experiments. Free-electron lasers (FELs) are capable of producing short-duration (< 10fs), high-energy X-ray pulses for a range of scientific applications. The recently activated Linac Coherent Light Source (LCLS) FEL facility at SLAC will support experiments which require synchronized light pulses for pump-probe schemes. They developed and operated a fiber optic RF transmission system to synchronize lasers to the emitted X-ray pulses, which was used to enable the first pump-probe experiments at the LCLS.

  12. Development of a BPM Lock-In Diagnostic System

    Energy Technology Data Exchange (ETDEWEB)

    Richard Dickson

    2003-05-12

    A system has been developed for the acquisition and analysis of high rate, time coherent BPM data across the Jefferson Lab's Continuous Electron Beam Accelerator Facility (CEBAF). This system will allow the acquisition of Beam Position Monitor (BPM) position and intensity information at a rate in excess 7 KHz for approximately 200 BPMs in a time synchronous manner. By inducing minute sinusoidal transverse beam motion in the CEBAF injector, with known phase relative to the synchronized BPM acquisition, it is possible to derive several types of useful information. Analysis of the BPM intensity data, which is proportional to beam current, by beating the signal with an in-phase sinusoidal representation of the transverse kick can localize beam scraping to a particular BPM. Similarly, real-time optics information may be deduced with an analysis of BPM position data. This paper will detail the frequency lock-in technique applied and present status.

  13. Critical Behavior of Light in Mode-Locked Lasers

    Science.gov (United States)

    Weill, Rafi; Rosen, Amir; Gordon, Ariel; Gat, Omri; Fischer, Baruch

    2005-06-01

    Light is shown to exhibit critical and tricritical behavior in passively mode-locked lasers with externally injected pulses. It is a first and unique example of critical phenomena in a one-dimensional many-body light-mode system. The phase diagrams consist of regimes with continuous wave, driven parapulses, spontaneous pulses via mode condensation, and heterogeneous pulses, separated by phase transition lines that terminate with critical or tricritical points. Enhanced non-Gaussian fluctuations and collective dynamics are present at the critical and tricritical points, showing a mode system analog of the critical opalescence phenomenon. The critical exponents are calculated and shown to comply with the mean field theory, which is rigorous in the light system.

  14. Application of lock-in thermography non destructive technique to CFC armoured plasma facing components

    International Nuclear Information System (INIS)

    Escourbiac, F.; Constans, S.; Courtois, X.; Durocher, A.

    2007-01-01

    A non destructive testing technique - so called modulated photothermal thermography or lock-in thermography - has been set-up for plasma facing components examination. Reliable measurements of phase contrast were obtained on 8 mm carbon fiber composite (CFC) armoured W7-X divertor component with calibrated flaws. A 3D finite element analysis allowed the correlation of the measured phase contrast and showed that a 4 mm strip flaw can be detected at the CFC/copper interface

  15. Mode-locked silicon evanescent lasers.

    Science.gov (United States)

    Koch, Brian R; Fang, Alexander W; Cohen, Oded; Bowers, John E

    2007-09-03

    We demonstrate electrically pumped lasers on silicon that produce pulses at repetition rates up to 40 GHz. The mode locked lasers generate 4 ps pulses with low jitter and extinction ratios above 18 dB, making them suitable for data and telecommunication transmitters and for clock generation and distribution. Results of both passive and hybrid mode locking are discussed. This type of device could enable new silicon based integrated technologies, such as optical time division multiplexing (OTDM), wavelength division multiplexing (WDM), and optical code division multiple access (OCDMA).

  16. Drag and Torque on Locked Screw Propeller

    Directory of Open Access Journals (Sweden)

    Tomasz Tabaczek

    2014-09-01

    Full Text Available Few data on drag and torque on locked propeller towed in water are available in literature. Those data refer to propellers of specific geometry (number of blades, blade area, pitch and skew of blades. The estimation of drag and torque of an arbitrary propeller considered in analysis of ship resistance or propulsion is laborious. The authors collected and reviewed test data available in the literature. Based on collected data there were developed the empirical formulae for estimation of hydrodynamic drag and torque acting on locked screw propeller. Supplementary CFD computations were carried out in order to prove the applicability of the formulae to modern moderately skewed screw propellers.

  17. John Locke on persons and personal identity

    OpenAIRE

    Boeker, Ruth

    2013-01-01

    John Locke claims both that ‘person’ is a forensic term and that personal identity consists in sameness of consciousness. The aim of my dissertation is to explain and critically assess how Locke links his moral and legal account of personhood to his account of personal identity in terms of sameness of consciousness. My interpretation of Locke’s account of persons and personal identity is embedded in Locke’s sortal-dependent account of identity. Locke’s sortal-dependent ac...

  18. Optimal database locks for efficient integrity checking

    DEFF Research Database (Denmark)

    Martinenghi, Davide

    2004-01-01

    In concurrent database systems, correctness of update transactions refers to the equivalent effects of the execution schedule and some serial schedule over the same set of transactions. Integrity constraints add further semantic requirements to the correctness of the database states reached upon...... the execution of update transactions. Several methods for efficient integrity checking and enforcing exist. We show in this paper how to apply one such method to automatically extend update transactions with locks and simplified consistency tests on the locked entities. All schedules produced in this way...

  19. Navigation Study, Colorado Locks, Colorado River, Matagorda, Texas

    National Research Council Canada - National Science Library

    McCollum, Randy

    2000-01-01

    A 1:70 physical navigation model was built to replicate the Matagorda Locks, approximately one mile of the GIWW east of the locks, approximately one-half mile of the Colorado River north of the GIWW...

  20. Robust tilt and lock mechanism for hopping actuator

    Energy Technology Data Exchange (ETDEWEB)

    Salton, Jonathan R.; Buerger, Stephen; Dullea, Kevin J.; Marron, Lisa C.; Salisbury, Curt Michael; Spletzer, Barry Louis

    2017-02-07

    A tilt and lock apparatus that includes a tilt servomechanism, a spiral torsion spring, a lock wheel, and a lock hook is described herein. The spiral torsion spring is mechanically coupled to the tilt servomechanism and the lock wheel (which includes an opening). When a shaft is positioned through the opening, rotation of the lock wheel is in unison with rotation of the shaft. An external surface of the lock wheel includes one or more grooves. The lock hook includes a head that engages and disengages the grooves. The lock wheel is stationary when the head engages one of the grooves and is rotatable when the head disengages the grooves. The head and the grooves are geometrically aligned when engaged to prevent creation of a force that acts to disengage the head responsive to an applied force acting on the shaft.

  1. Locks at reactor safety containments of nuclear power plants

    International Nuclear Information System (INIS)

    1978-12-01

    The rule is to be applied for material access locks. A material access lock as defined by this rule is a pressure resistant and technically gas-tight hollow body that is connected with the containment and has got two doors, the inner door of which connects the lock chamber with the interior of the containment and the outer door connects the lock chamber with the outside. It serves exclusively for transferring material or objects. (orig./HP) [de

  2. Performance Monitoring System: Summary of Lock Statistics. Revision 1.

    Science.gov (United States)

    1985-12-01

    2751 84 4057 4141 526 798 18 1342 5727 19 5523 3996 4587 8583 1056 1630 35 2721 6536LOCK A DAMI 2 AUXILIARY I Ins NO DATA RECORDD FOR THIS LOCK- " LOCK I...TOTAL (KTOMS) ’ - (AVt OPNP ETC) ’’ ,q [ " ARKANSAS RIVER "" FORRELL LOCK IP 7A/3TRC 9/N83 UPBOUID STATISTICS ISO 53 42 M6 553 356 909 221 41 21 M8

  3. Multiprocessor Real-Time Locking Protocols for Replicated Resources

    Science.gov (United States)

    2016-07-01

    assignment problem, the ac- tual identities of the allocated replicas must be known. When locking protocols are used, tasks may experience delays due to both...Multiprocessor Real-Time Locking Protocols for Replicated Resources ∗ Catherine E. Jarrett1, Kecheng Yang1, Ming Yang1, Pontus Ekberg2, and James H...replicas to execute. In prior work on replicated resources, k-exclusion locks have been used, but this restricts tasks to lock only one replica at a time. To

  4. Lock-free parallel garbage collection

    NARCIS (Netherlands)

    H. Gao; J.F. Groote (Jan Friso); W.H. Hesselink (Wim)

    2005-01-01

    htmlabstract This paper presents a lock-free parallel algorithm for mark&sweep garbage collection (GC) in a realistic model using synchronization primitives compare-and-swap (CAS) and load-linked/store-conditional (LL/SC) offered by machine architectures. Mutators and collectors can simultaneously

  5. A Mode Locked UV-FEL

    CERN Document Server

    Parvin, Parviz

    2004-01-01

    An appropriate resonator has been designed to generate femtosecond mode locked pulses in a UV FEL with the modulator performance based on the gain switching. The gain broadening due to electron energy spread affects on the gain parameters, small signal gain (γ0) and saturation intensity (Is), to determine the optimum output coupling as small.

  6. A locked nucleic Acid-based nanocrawler

    DEFF Research Database (Denmark)

    Astakhova, I Kira; Pasternak, Karol; Campbell, Meghan A

    2013-01-01

    Herein we introduce a novel fluorescent LNA/DNA machine, a nanocrawler, which reversibly moves along a directionally polar complementary road controlled by affinity-enhancing locked nucleic acid (LNA) monomers and additional regulatory strands. Polyaromatic hydrocarbon (PAH) dyes attached to 2...

  7. 49 CFR 236.742 - Dog, locking.

    Science.gov (United States)

    2010-10-01

    ... 49 Transportation 4 2010-10-01 2010-10-01 false Dog, locking. 236.742 Section 236.742 Transportation Other Regulations Relating to Transportation (Continued) FEDERAL RAILROAD ADMINISTRATION..., MAINTENANCE, AND REPAIR OF SIGNAL AND TRAIN CONTROL SYSTEMS, DEVICES, AND APPLIANCES Definitions § 236.742 Dog...

  8. A New Perspective on Job Lock

    Science.gov (United States)

    Huysse-Gaytandjieva, Anna; Groot, Wim; Pavlova, Milena

    2013-01-01

    This paper analyses the situation when employees fail to adapt to overall job dissatisfaction. By combining the existing knowledge in economics on job lock and in psychology on employees' feeling of being "stuck" at work, the paper explains why some employees fail to adapt when dissatisfied with their job. Thus, the paper aims to expand…

  9. Locks & keys service moves to building 55

    CERN Multimedia

    2012-01-01

    Please note that as of July 12 Locks & keys service will be at building 55 second floor. The opening hours are as follows: 08:30 am to 12:30 pm - 1:30 pm to 5:30 pm. The procedures and rules relating to applications for key and cylinder have not changed. GI-IS Group

  10. Locking plate fixation for proximal humerus fractures.

    LENUS (Irish Health Repository)

    Burke, Neil G

    2012-02-01

    Locking plates are increasingly used to surgically treat proximal humerus fractures. Knowledge of the bone quality of the proximal humerus is important. Studies have shown the medial and dorsal aspects of the proximal humeral head to have the highest bone strength, and this should be exploited by fixation techniques, particularly in elderly patients with osteoporosis. The goals of surgery for proximal humeral fractures should involve minimal soft tissue dissection and achieve anatomic reduction of the head complex with sufficient stability to allow for early shoulder mobilization. This article reviews various treatment options, in particular locking plate fixation. Locking plate fixation is associated with a high complication rate, such as avascular necrosis (7.9%), screw cutout (11.6%), and revision surgery (13.7%). These complications are frequently due to the varus deformation of the humeral head. Strategic screw placement in the humeral head would minimize the possibility of loss of fracture reduction and potential hardware complications. Locking plate fixation is a good surgical option for the management of proximal humerus fractures. Complications can be avoided by using better bone stock and by careful screw placement in the humeral head.

  11. Automated Identification of MHD Mode Bifurcation and Locking in Tokamaks

    Science.gov (United States)

    Riquezes, J. D.; Sabbagh, S. A.; Park, Y. S.; Bell, R. E.; Morton, L. A.

    2017-10-01

    Disruption avoidance is critical in reactor-scale tokamaks such as ITER to maintain steady plasma operation and avoid damage to device components. A key physical event chain that leads to disruptions is the appearance of rotating MHD modes, their slowing by resonant field drag mechanisms, and their locking. An algorithm has been developed that automatically detects bifurcation of the mode toroidal rotation frequency due to loss of torque balance under resonant braking, and mode locking for a set of shots using spectral decomposition. The present research examines data from NSTX, NSTX-U and KSTAR plasmas which differ significantly in aspect ratio (ranging from A = 1.3 - 3.5). The research aims to examine and compare the effectiveness of different algorithms for toroidal mode number discrimination, such as phase matching and singular value decomposition approaches, and to examine potential differences related to machine aspect ratio (e.g. mode eigenfunction shape variation). Simple theoretical models will be compared to the dynamics found. Main goals are to detect or potentially forecast the event chain early during a discharge. This would serve as a cue to engage active mode control or a controlled plasma shutdown. Supported by US DOE Contracts DE-SC0016614 and DE-AC02-09CH11466.

  12. CMOS Optoelectronic Lock-In Amplifier With Integrated Phototransistor Array.

    Science.gov (United States)

    An Hu; Chodavarapu, Vamsy P

    2010-10-01

    We describe the design and development of an optoelectronic lock-in amplifier (LIA) for optical sensing and spectroscopy applications. The prototype amplifier is fabricated using Taiwan Semiconductor Manufacturing Co. complementary metal-oxide semiconductor 0.35-μm technology and uses a phototransistor array (total active area is 400 μm × 640μm) to convert the incident optical signals into electrical currents. The photocurrents are then converted into voltage signals using a transimpedance amplifier for subsequent convenient signal processing by the LIA circuitry. The LIA is optimized to be operational at 20-kHz modulation frequency but is operational in the frequency range from 13 kHz to 25 kHz. The system is tested with a light-emitting diode (LED) as the light source. The noise and signal distortions are suppressed with filters and a phase-locked loop (PLL) implemented in the LIA. The output dc voltage of the LIA is proportional to the incident optical power. The minimum measured dynamic reserve and sensitivity are 1.31 dB and 34 mV/μW, respectively. The output versus input relationship has shown good linearity. The LIA consumes an average power of 12.79 mW with a 3.3-V dc power supply.

  13. A photovoltaic module diagnostic setup for lock-in-thermography and lock-in electroluminescence imaging

    DEFF Research Database (Denmark)

    Parikh, Harsh; Spataru, Sergiu; Sera, Dezso

    2018-01-01

    Electroluminescence (EL) imaging and infrared (IRT) thermography techniques have become indispensable tools in recent years for health diagnostic of PV modules in solar industry application. Complementary to these imaging methods, lock-in techniques can effectively remove noise by periodically...... modulating the input signal and averaging it over a desired number of periods. We propose a combined lock-in EL and lock-in IRT diagnostic setup for accurate analysis of different types of faults occurring in a solar module. The setup is built around a Goldeye CL-033 high-speed SWIR camera, which can acquire...... experimental work on a (36/72) cell solar module using combined (EL) or (IRT) lock-in-thermography. The setup allows one to investigate the different technological problems that can occur when performing PV diagnostics in drone-based inspections....

  14. Navigation Study of Lower Lock Approach, John Day Lock and Dam, Columbia River, Oregon

    National Research Council Canada - National Science Library

    Wilson, Donald

    2001-01-01

    Representatives of the Columbia River Towing Association reported recent structural and/or operational changes at John Day Lock and Dam have created difficult navigation conditions for tows entering...

  15. 30 CFR 56.12068 - Locking transformer enclosures.

    Science.gov (United States)

    2010-07-01

    ... 30 Mineral Resources 1 2010-07-01 2010-07-01 false Locking transformer enclosures. 56.12068 Section 56.12068 Mineral Resources MINE SAFETY AND HEALTH ADMINISTRATION, DEPARTMENT OF LABOR METAL AND... § 56.12068 Locking transformer enclosures. Transformer enclosures shall be kept locked against...

  16. Dynamics of injection locking in a solid-state laser with intracavity second-harmonic generation

    International Nuclear Information System (INIS)

    Zolotoverkh, I I; Lariontsev, E G

    2000-01-01

    The dynamics of oscillation in a solid-state laser with intracavity second-harmonic generation under the influence of an external signal at the second-harmonic frequency injected into its cavity in the presence of feedback at the double frequency is theoretically studied. Boundaries of the regions of injection locking for three stationary laser states differing in the nonlinear phase incursion caused by radiation conversion into the second harmonic are found. Relaxation oscillations in the stationary state of injection locking are studied. It is shown that the second relaxation frequency, which is related to phase perturbations of the second harmonic and perturbations of the phase difference of waves in a nonlinear crystal, is excited in a single-mode solid-state laser in addition to the fundamental frequency of relaxation oscillations. Conditions are found under which relaxation oscillations at the second relaxation frequency are excited. (lasers)

  17. An Exploratory Study on the Optimized Test Conditions of the Lock-in Thermography Technique

    International Nuclear Information System (INIS)

    Cho, Yong Jin

    2011-01-01

    This work is devoted to the technique application of lock-in infrared thermography in the shipbuilding and ocean engineering industry. For this purpose, an exploratory study to find the optimized test conditions is carried out by the design of experiments. It has been confirmed to be useful method that the phase contrast images were quantified by a reference image and weighted by defect hole size. Illuminated optical intensity of lower or medium strength give a good result for getting a phase contrast image. In order to get a good phase contrast image, lock-in frequency factors should be high in proportion to the illuminated optical intensity. The integration time of infrared camera should have been inversely proportional to the optical intensity. The other hand, the difference of specimen materials gave a slightly biased results not being discriminative reasoning

  18. Simple lock-in detection technique utilizing multiple harmonics for digital PGC demodulators.

    Science.gov (United States)

    Duan, Fajie; Huang, Tingting; Jiang, Jiajia; Fu, Xiao; Ma, Ling

    2017-06-01

    A simple lock-in detection technique especially suited for digital phase-generated carrier (PGC) demodulators is proposed in this paper. It mixes the interference signal with rectangular waves whose Fourier expansions contain multiple odd or multiple even harmonics of the carrier to recover the quadrature components needed for interference phase demodulation. In this way, the use of a multiplier is avoided and the efficiency of the algorithm is improved. Noise performance with regard to light intensity variation and circuit noise is analyzed theoretically for both the proposed technique and the traditional lock-in technique, and results show that the former provides a better signal-to-noise ratio than the latter with proper modulation depth and average interference phase. Detailed simulations were conducted and the theoretical analysis was verified. A fiber-optic Michelson interferometer was constructed and the feasibility of the proposed technique is demonstrated.

  19. A CMOS delay locked loop and sub-nanosecond time-to-digital converter chip

    International Nuclear Information System (INIS)

    Santos, D.M.; Dow, S.F.; Flasck, J.M.; Levi, M.E.

    1996-01-01

    Phase-locked loops have been employed in the past to obtain sub-nanosecond time resolution in high energy physics and nuclear science applications. An alternative solution based on a delay-locked loop (DLL) is described. This solution allows for a very high level of integration yet still offers resolution in the sub-nanosecond regime. Two variations on this solution are outlined. A novel phase detector, based on the Mueller C-element, is used to implement a charge pump where the injected charge approaches zero as the loop approaches lock on the leading edge of an input clock reference. This greatly reduces timing jitter. In the second variation the loop locks to both the leading and trailing clock edges. In this second implementation, software coded layout generators are used to automatically layout a highly integrated, multichannel, time-to-digital converter (TDC) targeted for one specific frequency. The two circuits, DLL and TDC, are implemented in CMOS 1.2 microm and 0.8 microm technologies, respectively. Test results show a timing jitter of less than 30 ps for the DLL circuit and less than 190 ps integral and differential nonlinearity for the TDC circuit

  20. A CMOS delay locked loop and sub-nanosecond time-to-digital converter chip

    International Nuclear Information System (INIS)

    Santos, D.M.; Dow, S.F.; Levi, M.E.

    1995-12-01

    Many high energy physics and nuclear science applications require sub-nanosecond time resolution measurements over many thousands of detector channels. Phase-locked loops have been employed in the past to obtain accurate time references for these measurements. An alternative solution, based on a delay-locked loop (DLL) is described. This solution allows for a very high level of integration yet still offers resolution in the sub-nanosecond regime. Two variations on this solution are outlined. A novel phase detector, based on the Muller C element, is used to implement a charge pump where the injected charge approaches zero as the loop approaches lock on the leading edge of an input clock reference. This greatly reduces timing jitter. In the second variation the loop locks to both the leading and trailing clock edges. In this second implementation, software coded layout generators are used to automatically layout a highly integrated, multi-channel, time to digital converter (TDC). Complex clock generation can be, achieved by taking symmetric taps off the delay elements. The two circuits, DLL and TDC, were implemented in a CMOS 1.2μm and 0.8μm technology, respectively. Test results show a timing jitter of less than 35 ps for the DLL circuit and better solution for the TDC circuit

  1. Relationship Between Locked Modes and Disruptions in the DIII-D Tokamak

    Science.gov (United States)

    Sweeney, Ryan

    This thesis is organized into three body chapters: (1) the first use of naturally rotating tearing modes to diagnose intrinsic error fields is presented with experimental results from the EXTRAP T2R reversed field pinch, (2) a large scale study of locked modes (LMs) with rotating precursors in the DIII-D tokamak is reported, and (3) an in depth study of LM induced thermal collapses on a few DIII-D discharges is presented. The amplitude of naturally rotating tearing modes (TMs) in EXTRAP T2R is modulated in the presence of a resonant field (given by the superposition of the resonant intrinsic error field, and, possibly, an applied, resonant magnetic perturbation (RMP)). By scanning the amplitude and phase of the RMP and observing the phase-dependent amplitude modulation of the resonant, naturally rotating TM, the corresponding resonant error field is diagnosed. A rotating TM can decelerate and lock in the laboratory frame, under the effect of an electromagnetic torque due to eddy currents induced in the wall. These locked modes often lead to a disruption, where energy and particles are lost from the equilibrium configuration on a timescale of a few to tens of milliseconds in the DIII-D tokamak. In fusion reactors, disruptions pose a problem for the longevity of the reactor. Thus, learning to predict and avoid them is important. A database was developed consisting of ˜ 2000 DIII-D discharges exhibiting TMs that lock. The database was used to study the evolution, the nonlinear effects on equilibria, and the disruptivity of locked and quasi-stationary modes with poloidal and toroidal mode numbers m = 2 and n = 1 at DIII-D. The analysis of 22,500 discharges shows that more than 18% of disruptions present signs of locked or quasi-stationary modes with rotating precursors. A parameter formulated by the plasma internal inductance li divided by the safety factor at 95% of the toroidal flux, q95, is found to exhibit predictive capability over whether a locked mode will

  2. Power spectrum of an injection-locked Josephson oscillator

    International Nuclear Information System (INIS)

    Stancampiano, C.V.; Shapiro, S.

    1975-01-01

    Experiments have shown that a Josephson oscillator, exposed to a weak narrow-band input signal, exhibits behavior characteristic of an injection-locked oscillator. When in lock, Adler's theory of injection locking describes the experimental observations reasonably well. The range of applicability of the theory is extended to the out-of-lock regime where a spectrum of output frequencies is observed. Obtaining the theoretical output power spectrum requires solving a differential equation having the same form as the equation describing the resistively shunted junction model of Stewart and of McCumber. Experimental measurements of the output spectrum of a nearly locked Josephson oscillator are shown to be in reasonable agreement with the theory. Additional results discussed briefly include the observation of a frequency dependence of the locked Josephson oscillator output and experiments in which a Josephson oscillator-mixer was injection locked by a weak signal at the rf

  3. Vortex structure in superfluid color-flavor locked quark matter

    Directory of Open Access Journals (Sweden)

    Alford Mark G.

    2016-01-01

    Full Text Available The core region of a neutron star may feature quark matter in the color-flavor-locked (CFL phase. The CFL condensate breaks the baryon number symmetry, such that the phenomenon of superfluidity arises. If the core of the star is rotating, vortices will form in the superfluid, carrying the quanta of angular momentum. In a previous study we have solved the question of stability of these vortices, where we found numerical proof of a conjectured instability, according to which superfluid vortices will decay into an arrangement of so-called semi-superfluid fluxtubes. Here we report first results of an extension of our framework that allows us to study multi-vortex dynamics. This will in turn enable us to investigate the structure of semi-superfluid string lattices, which could be relevant to study pinning phenomena at the boundary of the core.

  4. 408-fs SESAM mode locked Cr:ZnSe laser

    Science.gov (United States)

    Bu, Xiangbao; Shi, Yuhang; Xu, Jia; Li, Huijuan; Wang, Pu

    2018-01-01

    We report self-starting femtosecond operation of a 127-MHz SESAM mode locked Cr:ZnSe laser around 2420 nm. A thulium doped double clad fiber laser at 1908 nm was used as the pumping source. In the normal dispersion regime, stable pulse pairs with constant phase differences in the multipulse regime were observed. The maximum output power was 342 mW with respect to incident pump power of 4.8 W and the corresponding slope efficiency was 10.4%. By inserting a piece of sapphire plate, dispersion compensation was achieved and the intra-cavity dispersion was moved to the anomalous regime. A maximum output power of 403 mW was obtained and the corresponding slope efficiency was 12.2%. Pulse width was measured to be 408 fs by a collinear autocorrelator using two-photon absorption in an InGaAs photodiode. The laser spectrum in multipulse operation showed a clear periodic modulation.

  5. Subharmonic frequency locking in the resistive Josephson thermometer

    International Nuclear Information System (INIS)

    van Veldhuizen, M.; Fowler, H.A.

    1985-01-01

    Phase-locked oscillatory solutions are examined as a basis for the dc impedance of the resistive superconducting quantum-interference device Josephson thermometer. The calculations are based on the resistively shunted junction model in the limit 2πL/sub s/I/sub c//Phi 0 > or =1, where L/sub s/ is the loop inductance and I/sub c/ is the junction critical current, and for a junction resistance large compared with the external shunt resistance. An algorithm for representing frequency entrainment in (kappa,ω) space (drive amplitude, frequency) leads to zones with rotation number p/q having the form of leaf-shaped regions joined and overlapping at their tips. High-resonance zones are very thin and locally similar. No chaotic behavior has been observed. The model can simulate the ''rising'' curves of dc impedance as a function of drive amplitude

  6. Conformational lock and dissociative thermal inactivation of lentil seedling amine oxidase.

    Science.gov (United States)

    Moosavi-Nejad, S Zahra; Moosavi-Movahedi, Ali-Akbar; Rezaei-Tavirani, Mostafa; Floris, Giovanni; Medda, Rosaria

    2003-03-31

    The kinetics of thermal inactivation of copper-containing amine oxidase from lentil seedlings were studied in a 100 mM potassium phosphate buffer, pH 7, using putrescine as the substrate. The temperature range was between 47-60 degrees C. The thermal inactivation curves were not linear at 52 and 57 degrees C; three linear phases were shown. The first phase gave some information about the number of dimeric forms of the enzyme that were induced by the higher temperatures using the "conformational lock" pertaining theory to oligomeric enzyme. The "conformational lock" caused two additional dimeric forms of the enzyme when the temperature increased to 57 degrees C. The second and third phases were interpreted according to a dissociative thermal inactivation model. These phases showed that lentil amine oxidase was reversibly-dissociated before the irreversible thermal inactivation. Although lentil amine oxidase is not a thermostable enzyme, its dimeric structure can form "conformational lock," conferring a structural tolerance to the enzyme against heat stress.

  7. Radiation detection from phase-locked serial dc SQUID arrays

    DEFF Research Database (Denmark)

    Kaplunenko, V. K.; Mygind, Jesper; Pedersen, Niels Falsig

    1993-01-01

    We report on synchronous operation of series arrays of inductively coupled superconducting quantum interference devices (SQUIDs). Each array consisted of N=3 or 11 dc SQUIDs with common inductances providing a strong interaction between neighboring cells. Externally shunted (betac[approximately-e......We report on synchronous operation of series arrays of inductively coupled superconducting quantum interference devices (SQUIDs). Each array consisted of N=3 or 11 dc SQUIDs with common inductances providing a strong interaction between neighboring cells. Externally shunted (betac...

  8. Tubular Extendible Lock-Out Composite Boom (STELOC), Phase II

    Data.gov (United States)

    National Aeronautics and Space Administration — Mass and volume efficient solar arrays are sought by NASA, DoD and commercial space to enable high power missions from 20-50 kW in the near term and eventually up to...

  9. Linewidth and phase locking of Josephson flux flow oscillators

    DEFF Research Database (Denmark)

    Mygind, Jesper; Koshelets, V. P.; Shitov, S. V.

    2000-01-01

    by the resolution bandwidth of the spectrum analyzer) has been measured. This linewidth is far below the fundamental level given by shot and thermal noise of the free-running tunnel junction. The damping mechanisms are discussed and related to the self-excitation Of quasiparticles. Narrow linewidth, wide...

  10. Nanometer frequency synthesis beyond the phase-locked loop

    CERN Document Server

    Xiu, Liming

    2012-01-01

    This text presents a latest technology in frequency synthesis. The technology includes three key components: Time-Average-Frequency, Flying-Adder architecture, and Digital-to-Frequency converter. The coverage presents the case, through real application examples, that this Flying-Adder technology creates a new frontier for modern IC design. In so doing, it also discusses the weaknesses of current frequency synthesis techniques in dealing with certain problems in modern IC design. The result is a complete picture of this technology for professional design engineers, researchers, and advanced students.

  11. Phase-Locked Semiconductor Quantum Well Laser Arrays.

    Science.gov (United States)

    1987-03-01

    heated monocrystalline substrate. 149 APPENDIX B. A TECHNOLOGICAL APPENDIX 150 The general topic of molecular beam epitaxy (MBE) of compound semi...APPENDIX B. A TECHNOLOGICAL APPENDIX 151 - MONOCRYSTALLINE GaAs SUBSTRATE MOLECULAR / BEAMS...for 30 minutes at 300 C. During this time, the growth chamber cryo- panel is cooled with liquid nitrogen and the sources in the effusion cells are

  12. Multi-frequency phase locking in human somatosensory cortex

    NARCIS (Netherlands)

    Langdon, A.J.; Boonstra, T.W.; Breakspear, M.

    2011-01-01

    Cortical population responses to sensory input arise from the interaction between external stimuli and the intrinsic dynamics of the densely interconnected neuronal population. Although there is a large body of knowledge regarding single neuron responses to periodic stimuli, responses at the scale

  13. Three Alternative Symbol-Lock Detectors

    Science.gov (United States)

    Shihabi, Mazen M.; Hinedi, Sami M.; Shah, Biren N.

    1993-01-01

    Three symbol-lock detectors proposed as alternatives in advanced receivers processing non-return-to-zero binary data signals. Two perform operations similar to those of older square-law and absolute-value types. However, integrals computed during nonoverlapping symbol periods and, therefore, only one integrator needed in each such detector. Proposed detectors simpler, but performances worse because noises in overlapping samples correlated, whereas noises in nonoverlapping samples not correlated. Third detector is signal-power-estimator type. Signal integrated during successive half symbol cycles, and therefore only one integrator needed. Half-cycle integrals multiplied to eliminate effect of symbol polarity, and products accumulated during M-cycle observation period to smooth out estimate of signal power. If estimated signal power exceeds threshold, delta, then lock declared.

  14. Traumatic knee extension deficit (the locked knee)

    DEFF Research Database (Denmark)

    Helmark, I C; Neergaard, K; Krogsgaard, M R

    2007-01-01

    In the present study we investigated the validity of magnetic resonance imaging (MRI) and arthroscopy in knees with acute, traumatic extension deficit (the "locked knee"), and evaluated whether arthroscopy of knees with no mechanical pathology could be avoided by MRI evaluation. The study consisted...... of 50 patients who had an acute, traumatic extension deficit of the knee. All patients were submitted to MRI prior to arthroscopy. Following MRI and surgery, standardized forms were filled out, attempting to objectify the findings. The orthopaedic surgeon was not aware of the MRI result prior to surgery....... Evaluating MRI, all grade-3 meniscal lesions were considered able to cause a mechanical block as well as acute partial or total anterior cruciate ligament (ACL)-ruptures. ACL-ruptures with an old appearance were not considered able to cause locking. Assuming that arthroscopy was the gold standard...

  15. Mode-locking via dissipative Faraday instability.

    Science.gov (United States)

    Tarasov, Nikita; Perego, Auro M; Churkin, Dmitry V; Staliunas, Kestutis; Turitsyn, Sergei K

    2016-08-09

    Emergence of coherent structures and patterns at the nonlinear stage of modulation instability of a uniform state is an inherent feature of many biological, physical and engineering systems. There are several well-studied classical modulation instabilities, such as Benjamin-Feir, Turing and Faraday instability, which play a critical role in the self-organization of energy and matter in non-equilibrium physical, chemical and biological systems. Here we experimentally demonstrate the dissipative Faraday instability induced by spatially periodic zig-zag modulation of a dissipative parameter of the system-spectrally dependent losses-achieving generation of temporal patterns and high-harmonic mode-locking in a fibre laser. We demonstrate features of this instability that distinguish it from both the Benjamin-Feir and the purely dispersive Faraday instability. Our results open the possibilities for new designs of mode-locked lasers and can be extended to other fields of physics and engineering.

  16. Quantum locking of mirrors in interferometers.

    Science.gov (United States)

    Courty, Jean-Michel; Heidmann, Antoine; Pinard, Michel

    2003-02-28

    We show that quantum noise in very sensitive interferometric measurements such as gravitational-wave detectors can be drastically modified by quantum feedback. We present a new scheme based on active control to lock the motion of a mirror to a reference mirror at the quantum level. This simple technique allows one to reduce quantum effects of radiation pressure and to greatly enhance the sensitivity of the detection.

  17. Dither Cavity Length Controller with Iodine Locking

    Directory of Open Access Journals (Sweden)

    Lawson Marty

    2016-01-01

    Full Text Available A cavity length controller for a seeded Q-switched frequency doubled Nd:YAG laser is constructed. The cavity length controller uses a piezo-mirror dither voltage to find the optimum length for the seeded cavity. The piezo-mirror dither also dithers the optical frequency of the output pulse. [1]. This dither in optical frequency is then used to lock to an Iodine absorption line.

  18. Programmable Self-Locking Origami Mechanical Metamaterials.

    Science.gov (United States)

    Fang, Hongbin; Chu, Shih-Cheng A; Xia, Yutong; Wang, Kon-Well

    2018-04-01

    Developing mechanical metamaterials with programmable properties is an emerging topic receiving wide attention. While the programmability mainly originates from structural multistability in previously designed metamaterials, here it is shown that nonflat-foldable origami provides a new platform to achieve programmability via its intrinsic self-locking and reconfiguration capabilities. Working with the single-collinear degree-4 vertex origami tessellation, it is found that each unit cell can self-lock at a nonflat configuration and, therefore, possesses wide design space to program its foldability and relative density. Experiments and numerical analyses are combined to demonstrate that by switching the deformation modes of the constituent cell from prelocking folding to postlocking pressing, its stiffness experiences a sudden jump, implying a limiting-stopper effect. Such a stiffness jump is generalized to a multisegment piecewise stiffness profile in a multilayer model. Furthermore, it is revealed that via strategically switching the constituent cells' deformation modes through passive or active means, the n-layer metamaterial's stiffness is controllable among 2 n target stiffness values. Additionally, the piecewise stiffness can also trigger bistable responses dynamically under harmonic excitations, highlighting the metamaterial's rich dynamic performance. These unique characteristics of self-locking origami present new paths for creating programmable mechanical metamaterials with in situ controllable mechanical properties. © 2018 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

  19. [Tibiotalocalcaneal arthrodesis using a humeral locking plate].

    Science.gov (United States)

    Cabrera Méndez, M P; Gamba, C; Hernández, E; Molano, J; Andrade, J C

    2016-01-01

    To describe the results of tibiotalocalcáneal arthrodesis (TTC) using a humeral locking plate. A retrospective, observational study was conducted between January 2007 and December 2013 in the Hospital Militar Central de Bogotá. The study included patients with symptomatic osteoarthritis diagnosed clinically and radiologically, and who underwent TTC arthrodesis using a humeral locking plate with a minimum follow up of 6 months. The total number patients was 35, of whom 7 (20%) were women and 28 (80%) men, with a mean age 36.3 years (19.77). 74% with post-traumatic arthritis, most of them secondary to gunshot wounds and fragmentation weapons, and neuropathic in 20%. An autogenous graft was used in 13 cases, and 14 cases using both, with a mean consolidation time of 4.37 months. Complications include, delayed union in 3 cases, and surgical site infection in 4. The postoperative functionality (AOFAS) mean was 66.7/100 points, with a score of 2.35 on a visual analogue pain scale. TTC arthrodesis using a humeral locking plate is a suitable option for fixing this type of arthrodesis, with a low rate of complications, and postoperative results that revealed satisfactory improvement in pain and consolidation. Copyright © 2015 SECOT. Published by Elsevier Espana. All rights reserved.

  20. Automated AC Electrical Impedance Measurement of Ceramic Oxides by means of a Lock-in Amplifier

    International Nuclear Information System (INIS)

    Al-Khawaja, S.; Al-Sous, M. B.; Nasrallah, F.

    2009-06-01

    In this study, the electrical impedance of some ceramic oxides has been investigated employing the Perkin Elmer DSP 7280 Lock-in amplifier, while recording the electric response versus frequency and temperature at constant amplitude. Via integral automation of this lock-in with other delicate electrical measuring devices, a control program has been developed to accurately and swiftly acquire the frequency response of the sample, in order to lately infer the resulting samples' impedance in volt and ampere. Two maxima peaks characterising the impedance, in the curve of the doped molybdenum oxide have been observed discerning two phases in the sample (doped with 40% of niobium oxide), which shows a remarkable relaxation related to improvement in its ionic conductivity within the solid phase, with respect to increasing frequency. (author)