Science.gov

Sample records for fast high peak-power

  1. Considerations for human exposure standards for fast-rise-time high-peak-power electromagnetic pulses.

    PubMed

    Merritt, J H; Kiel, J L; Hurt, W D

    1995-06-01

    Development of new emitter systems capable of producing high-peak-power electromagnetic pulses with very fast rise times and narrow pulse widths is continuing. Such directed energy weapons systems will be used in the future to defeat electronically vulnerable targets. Human exposures to these pulses can be expected during testing and operations. Development of these technologies for radar and communications purposes has the potential for wider environmental exposure, as well. Current IEEE C95.1-1991 human exposure guidelines do not specifically address these types of pulses, though limits are stated for pulsed emissions. The process for developing standards includes an evaluation of the relevant bioeffects data base. A recommendation has been made that human exposure to ultrashort electromagnetic pulses that engender electromagnetic transients, called precursor waves, should be avoided. Studies that purport to show the potential for tissue damage induced by such pulses were described. The studies cited in support of the recommendation were not relevant to the issues of tissue damage by propagated pulses. A number of investigations are cited in this review that directly address the biological effects of electromagnetic pulses. These studies have not shown evidence of tissue damage as a result of exposure to high-peak-power pulsed microwaves. It is our opinion that the current guidelines are sufficiently protective for human exposure to these pulses.

  2. High peak power diode stacks for high energy lasers

    NASA Astrophysics Data System (ADS)

    Negoita, Viorel C.; Vethake, Thilo; Jiang, John; Roff, Robert; Shih, Ming; Duck, Richard; Bauer, Marc; Mite, Roberto; Boucke, Konstantin; Treusch, Georg

    2015-02-01

    High energy solid state lasers are being developed for fusion experiments and other research applications where high energy per pulse is required but the repetition rate is rather low, around 10Hz. We report our results on high peak power diode laser stacks used as optical pumps for these lasers. The stacks are based on 10 mm bars with 4 mm cavity length and 55% fill factor, with peak power exceeding 500 W per bar. These bars are stacked and mounted on a cooler which provides backside cooling and electrical insulation. Currently we mount 25 bars per cooler for a nominal peak power of 12.5 kW, but in principle the mounting scheme can be scaled to a different number of devices depending on the application. Pretesting of these bars before soldering on the cooler enables us to select devices with similar wavelength and thus we maintain tight control of the spectral width (FWHM less than 6 nm). Fine adjustments of the centroid wavelength can be done by means of temperature of the cooling fluid or bias current. The available wavelength range spans from 880 nm to 1000 nm, and the wavelength of the entire assembly of stacks can be controlled to within 0.5 nm of the target value, which makes these stacks suitable for pumping a variety of gain media. The devices are fast axis collimated, with over 95% power being collimated in 6 mrad (full angle). The slow axis divergence is 9° (full angle) for 95% power content.

  3. Monolithic high peak-power coherent Doppler lidar system

    NASA Astrophysics Data System (ADS)

    Kotov, Leonid V.; Töws, Albert; Kurtz, Alfred; Bobkov, Konstantin K.; Aleshkina, Svetlana S.; Bubnov, Mikhail M.; Lipatov, Denis S.; Guryanov, Alexey N.; Likhachev, Mikhail

    2016-03-01

    In this work we present a monolithic lidar system, based on a newly-developed double-clad large mode area (LMA) polarization-maintaining Er-doped fiber and specially designed LMA passive components. Optimization of the fiber designs resulted in as high as 100 W of SBS limited peak power. The amplifier and its passive components (circulator and collimator) were integrated in an existing lidar system. The enhanced lidar system provides three times increase of scanning range compared to one based on standard telecom-grade amplifiers.

  4. Development and application of high peak power ultrafast lasers

    NASA Astrophysics Data System (ADS)

    Wang, Hai-Wen

    1999-10-01

    A compact, three-stage, multipass Ti:sapphire laser amplifier system has been developed that generates >40 TW pulses, with 24 fs pulse duration, at a repetition rate of 10Hz, and with an average power of 10 W. Output intensities in excess of 1 × 1019 W/cm2 have been produced. The technique of frequency-resolved optical gating was used to fully characterize the output pulses, and to carefully compare theoretical models with experiment. High dynamic range FROG measurements have been performed for the first time to characterize the temporal wings of the output pulses. Ultrafast lasers has been used to generate high-order harmonies. The shortest wavelength we observe, at 2.7 nm, is well within the ``water window'' region of x-ray transmission. In the case of all the noble gases, excellent agreement has been obtained between theoretical predictions for the highest harmonic photon energy generated and our experimental observations. We also observe that the individual harmonic peaks near the cutoff are well resolved for positively chirped pump pulses, but are unresolved in the case of negatively chirped excitation pulses. This behavior is explained by simulations that combine the chirp of the laser with the intrinsic phase shift of the harmonics. We have demonstrated that the intrinsic phase of the harmonic emission can be controlled by adjusting the chirp of the excitation laser pulse. Short wavelength recombinational x-ray lasers using high peak power ultrafast laser interaction with small clusters has also been investigated. A model has been developed to simulate this process. The model predicts that this is a feasible scheme to scale the recombinational x-ray laser to short wavelength. Experimental results have verified the hydrodynamic evolution predicted by this model.

  5. Assessment of the Genotoxic Effects of High Peak-Power Pulsed Electromagnetic Fields

    DTIC Science & Technology

    2003-06-01

    the Genotoxic Effects of High Peak-Power Pulsed Electromagnetic Fields 5c. PROGRAM ELEMENT NUMBER 5d. PROJECT NUMBER 5d. TASK NUMBER 6. AUTHOR(S) Dr... Genotoxic Effects of High Peak-Power Pulsed Electromagnetic Fields (EMFs) (From 1 June 2002 to 31 May 2003 for 12 months) Nikolai Konstantinovich Chemeris...International Science and Technology Center (ISTC), Moscow. 2 ISTC 2350 Assessment of the Genotoxic Effects of High Peak-Power Pulsed Electromagnetic Fields

  6. High Peak Power Ka-Band Gyrotron Oscillator Experiment.

    DTIC Science & Technology

    1987-09-21

    has also demonstrated frequency tuning over the range 28 to 49 GHz by operating in a family of TE.’ modes, with the azimuthal index m ranging from 4 to...10, by Varia- tion of the guide magnetic field. Operation is in general agrement with the predictions of theory. 1% 20. DISTRIBUTION /AVAILABIUTY OF...proved to be highly efficient, exceptionally high average power millimeter-wave sources.1 Operating at moderate currents and voltages (typically, S50

  7. High peak power gyroklystron with an inverted magnetron injection gun

    SciTech Connect

    Read, Michael E.; Lawson, Wesley; Miram, George; Marsden, David; Borchard, Philipp

    2005-12-01

    Calabazas Creek Research Inc. (CCR) has investigated the feasibility of a 30 GHz gyroklystron amplifier for driving advanced accelerators. Gyroklystrons have been shown to be efficient sources of high power radiation at frequencies above X-Band and are, therefore, well suited for driving high frequency accelerators. CCR's gyroklystron design includes a novel inverted magnetron injection gun (MIG) that allows support and cooling of the coaxial inner conductor of the circuit. This novel gun provides a very high quality electron beam, making it possible to achieve a cavity design with an efficiency of 54%. During Phase I, it was determined that the original frequency of 17 GHz was no longer well matched to the potential market. A survey of accelerator needs identified the Compact Linear Collider (CLIC) as requiring 30 GHz sources for testing of accelerator structures. Developers at CLIC are seeking approximately 25 MW per tube. This will result in the same power density as in the original 80 MW, 17 GHz device and will thus have essentially the same risk. CLIC will require initially 3-4 tubes and eventually 12-16 tubes. This quantity represents $5M-$10M in sales. In addition, gyroklystrons are of interest for radar systems and electron paramagnetic resonance (EPR) instruments. Following discussions with the Department of Energy, it was determined that changing the program goal to the CLIC requirement was in the best interest of CCR and the funding agency. The Phase I program resulted in a successful gyroklystron design with a calculated efficiency of 54% with an output power of 33 MW. Design calculations for all critical components are complete, and no significant technical issues remain.

  8. Neuroscience imaging enabled by new highly tunable and high peak power femtosecond lasers

    NASA Astrophysics Data System (ADS)

    Hakulinen, T.; Klein, J.

    2017-02-01

    Neuroscience applications benefit from recent developments in industrial femtosecond laser technology. New laser sources provide several megawatts of peak power at wavelength of 1040 nm, which enables simultaneous optogenetics photoactivation of tens or even hundreds of neurons using red shifted opsins. Another recent imaging trend is to move towards longer wavelengths, which would enable access to deeper layers of tissue due to lower scattering and lower absorption in the tissue. Femtosecond lasers pumping a non-collinear optical parametric amplifier (NOPA) enable the access to longer wavelengths with high peak powers. High peak powers of >10 MW at 1300 nm and 1700 nm allow effective 3-photon excitation of green and red shifted calcium indicators respectively and access to deeper, sub-cortex layers of the brain. Early results include in vivo detection of spontaneous activity in hippocampus within an intact mouse brain, where neurons express GCaMP6 activated in a 3-photon process at 1320 nm.

  9. Compact high voltage, high peak power, high frequency transformer for converter type modulator applications.

    PubMed

    Reghu, T; Mandloi, V; Shrivastava, Purushottam

    2016-04-01

    The design and development of a compact high voltage, high peak power, high frequency transformer for a converter type modulator of klystron amplifiers is presented. The transformer has been designed to operate at a frequency of 20 kHz and at a flux swing of ±0.6 T. Iron (Fe) based nanocrystalline material has been selected as a core for the construction of the transformer. The transformer employs a specially designed solid Teflon bobbin having 120 kV insulation for winding the high voltage secondary windings. The flux swing of the core has been experimentally found by plotting the hysteresis loop at actual operating conditions. Based on the design, a prototype transformer has been built which is per se a unique combination of high voltage, high frequency, and peak power specifications. The transformer was able to provide 58 kV (pk-pk) at the secondary with a peak power handling capability of 700 kVA. The transformation ratio was 1:17. The performance of the transformer is also presented and discussed.

  10. Compact high voltage, high peak power, high frequency transformer for converter type modulator applications

    NASA Astrophysics Data System (ADS)

    Reghu, T.; Mandloi, V.; Shrivastava, Purushottam

    2016-04-01

    The design and development of a compact high voltage, high peak power, high frequency transformer for a converter type modulator of klystron amplifiers is presented. The transformer has been designed to operate at a frequency of 20 kHz and at a flux swing of ±0.6 T. Iron (Fe) based nanocrystalline material has been selected as a core for the construction of the transformer. The transformer employs a specially designed solid Teflon bobbin having 120 kV insulation for winding the high voltage secondary windings. The flux swing of the core has been experimentally found by plotting the hysteresis loop at actual operating conditions. Based on the design, a prototype transformer has been built which is per se a unique combination of high voltage, high frequency, and peak power specifications. The transformer was able to provide 58 kV (pk-pk) at the secondary with a peak power handling capability of 700 kVA. The transformation ratio was 1:17. The performance of the transformer is also presented and discussed.

  11. Widely tunable, high peak power ultrafast laser sources in biological imaging (Conference Presentation)

    NASA Astrophysics Data System (ADS)

    Klein, Julien

    2017-02-01

    Widely tunable ultrafast lasers have enabled a large number of biological imaging techniques including point scanning multiphoton excited fluorescence (MPEF), SHG/THG and stimulated Raman imaging. Tunable ultrafast lasers offer spectral agility, covering the entire relative transparency window in live tissue (700-1300nnm) and flexibility with multi-color, synchronized outputs to support sophisticated label free techniques (e.g. stimulated Raman modalities). More recently newly available high peak power lasers based on Ytterbium technology drive advances in two-photon light-sheet, 3 photon excited fluorescence and holographic patterning for optogenetics photo-stimulation. These laser platforms offer a unique blend of compactness, ease of use and cost efficiency, and ideally complement tunable platforms typically based on Ti:Sapphire and IR optical parametric oscillators (OPO). We present various types of ultrafast laser architectures, link their optical characteristics to key bio-imaging requirements, and present relevant examples and images illustrating their impact in biological science. In particular we review the use of ultrafast lasers in optogenetics and fast in-vivo Calcium imaging deep in mouse brain.

  12. Photo-aligned liquid crystal devices for high-peak-power laser applications

    NASA Astrophysics Data System (ADS)

    Marshall, K. L.; Dorrer, C.; Vargas, M.; Gnolek, A.; Statt, M.; Chen, S.-H.

    2012-10-01

    Liquid crystal (LC) optical elements have proven themselves as robust and cost-effective components for high-peakpowerlaser systems such as the 60-beam, 40-TW OMEGA Nd:glass laser system at the University of Rochester'sLaboratory for Laser Energetics. Although buffed nylon 6/6 alignment layers are the de facto standard for high-peak-power applications, photoalignment coatings based on coumarin materials have demonstrated exceptionally high near-IR laser-damage resistance. Using conventional photolithographic patterning techniques, high-resolution, photoaligned, nematic LC beam-shaper devices with a contrast ratio of 430:1, a pixel size of 10 μm, an interpixel resolution of 1.7 μm, and laser-damage resistance of 30 J/cm2 (1054-nm, 1-ns pulse) have been demonstrated. Recently, we have extended this photoalignment process to other existing and potential high-peak-power LC optical devices that have previously used buffed alignment coatings. In addition to fabricating photoaligned LC wave-plate prototypes that meet all optical and performance specifications of LC devices currently used on OMEGA, novel LC polarization converters with continuously varying radial or azimuthal polarization states have been fabricated using the same high-damage-threshold materials. These polarization converters have applications not only in high-peak-power lasers but also in microscopy, electron acceleration, and machining.

  13. Laser-Damage-Resistant Photoalignment Layers for High-Peak-Power Liquid Crystal Device Applications

    SciTech Connect

    Marshall, K.L.; Gan, J.; Mitchell, G.; Papernov, S.; Rigatti, A.L.; Schmid, A.W.; Jacobs, S.D.

    2008-10-23

    Large-aperture liquid crystal (LC) devices have been in continuous use since 1995 as polarization control devices in the 40-TW, 351-nm, 60-beam OMEGA Nd:glass laser system at the University of Rochester’s Laboratory for Laser Energetics. The feasibility of using a noncontacting alignment method for high-peak-power LC laser optics by irradiation of a linearly photopolymerizable polymer with polarized UV light was recently investigated. These materials were found to have surprisingly large laser-damage thresholds at 1054 nm, approaching that of bare fused silica (30 to 60 J/cm^2). Their remarkable laser-damage resistance and ease in scalability to large apertures of these photoalignment materials, along with the ability to produce multiple alignment states by photolithographic patterning, opens new doorways for their application in LC devices for optics, photonics, and high-peak-power laser applications.

  14. High-peak power extended lifetime sealed TEA CO2 lasers

    NASA Astrophysics Data System (ADS)

    Smith, A. L. S.; Sephton, J. P.; Scott, G.

    1984-07-01

    Sustained long life operation (10 to the 6th - 10 to the 7th pulses) has been achieved with a series of high CO2 content (up to 50 percent) high peak power photo-preionized miniature TEA lasers. The loss of CO2 and formation of attaching oxygen is adequately controlled by the homogeneous catalysis of CO in CO2-N2-CO-He mixtures with the CO2 less than 30 percent. But with the highest peak power mixtures with greater CO2 contents and hydrogen replacing the helium, the formation of the attaching species O2 and H2O has been controlled by Hopcalite in a compact slow catalytic recombination loop supplementing the CO homogeneous catalysis.

  15. Robust Short-Pulse, High-Peak-Power Laser Transmitter for Optical Communications

    NASA Technical Reports Server (NTRS)

    Wright, Malcolm W.

    2009-01-01

    We report on a pulsed fiber based master oscillator power amplifier laser at 1550 nm to support moderate data rates with high peak powers in a compact package suitable for interplanetary optical communications. To accommodate pulse position modulation, the polarization maintaining laser transmitter generates pulses from 0.1 to 1 ns with variable duty cycle over a pulse repetition frequency range of 10 to 100 MHz.

  16. Asymptotically one-dimensional dynamics of high-peak-power ultrashort laser pulses

    NASA Astrophysics Data System (ADS)

    Voronin, A. A.; Zheltikov, A. M.

    2016-11-01

    Laser fields with peak powers P well above the critical power of self-focusing P cr are intrinsically unstable with respect to modulation instabilities, breaking up into multiple filaments as a part of a quintessentially three-dimensional nonlinear beam dynamics. Here, however, we show that—even for P \\gg P cr—the spatiotemporal field evolution can stay effectively one-dimensional. In this regime, observed as an asymptotic case of large diffraction lengths, the laser field can undergo a rich diversity of pulse transformation scenarios, including, most notably, pulse self-compression to subcycle field waveforms with very high peak powers, while remaining decoupled, within a limited propagation length, from beam dynamics.

  17. High average and peak power few-cycle laser pulses delivered by fiber pumped OPCPA system.

    PubMed

    Rothhardt, J; Hädrich, S; Seise, E; Krebs, M; Tavella, F; Willner, A; Düsterer, S; Schlarb, H; Feldhaus, J; Limpert, J; Rossbach, J; Tünnermann, A

    2010-06-07

    We report on a high power optical parametric amplifier delivering 8 fs pulses with 6 GW peak power. The system is pumped by a fiber amplifier and operated at 96 kHz repetition rate. The average output power is as high as 6.7 W, which is the highest average power few-cycle pulse laser reported so far. When stabilizing the seed oscillator, the system delivered carrier-envelop phase stable laser pulses. Furthermore, high harmonic generation up to the 33(th) order (21.8 nm) is demonstrated in a Krypton gas jet. In addition, the scalability of the presented laser system is discussed.

  18. Peak power ratio generator

    DOEpatents

    Moyer, Robert D.

    1985-01-01

    A peak power ratio generator is described for measuring, in combination with a conventional power meter, the peak power level of extremely narrow pulses in the gigahertz radio frequency bands. The present invention in a preferred embodiment utilizes a tunnel diode and a back diode combination in a detector circuit as the only high speed elements. The high speed tunnel diode provides a bistable signal and serves as a memory device of the input pulses for the remaining, slower components. A hybrid digital and analog loop maintains the peak power level of a reference channel at a known amount. Thus, by measuring the average power levels of the reference signal and the source signal, the peak power level of the source signal can be determined.

  19. Peak power ratio generator

    DOEpatents

    Moyer, R.D.

    A peak power ratio generator is described for measuring, in combination with a conventional power meter, the peak power level of extremely narrow pulses in the gigahertz radio frequency bands. The present invention in a preferred embodiment utilizes a tunnel diode and a back diode combination in a detector circuit as the only high speed elements. The high speed tunnel diode provides a bistable signal and serves as a memory device of the input pulses for the remaining, slower components. A hybrid digital and analog loop maintains the peak power level of a reference channel at a known amount. Thus, by measuring the average power levels of the reference signal and the source signal, the peak power level of the source signal can be determined.

  20. Ultra-high contrast frontend for high peak power fs-lasers at 1030 nm.

    PubMed

    Liebetrau, Hartmut; Hornung, Marco; Seidel, Andreas; Hellwing, Marco; Kessler, Alexander; Keppler, Sebastian; Schorcht, Frank; Hein, Joachim; Kaluza, Malte C

    2014-10-06

    We present the results from a new frontend within a double-chirped pulse amplification architecture (DCPA) utilizing crossed-polarized wave generation (XPW) for generating ultra-high contrast, 150 μJ-level, femtosecond seed pulses at 1030 nm. These pulses are used in the high energy class diode-pumped laser system Polaris at the Helmholtz Institute in Jena. Within this frontend, laser pulses from a 75 MHz oscillator-pulse train are extracted at a repetition rate of 1 Hz, temporally stretched, amplified and then recompressed reaching a pulse energy of 2 mJ, a bandwidth of 12 nm and 112 fs pulse duration at a center wavelength of 1030 nm. These pulses are temporally filtered via XPW in a holographic-cut BaF₂ crystal, resulting in 150 μJ pulse energy with an efficiency of 13 %. Due to this non-linear filtering, the relative intensity of the amplified spontaneous emission preceding the main pulse is suppressed to 2×10⁻¹³. This is, to the best of our knowledge, the lowest value achieved in a high peak power laser system operating at 1030 nm center wavelength.

  1. Single-mode single-frequency high peak power all-fiber MOPA at 1550 nm

    NASA Astrophysics Data System (ADS)

    Kotov, L. V.; Likhachev, M. E.; Bubnov, M. M.; Paramonov, V. M.; Belovolov, M. I.; Lipatov, D. S.; Guryanov, A. N.

    2014-10-01

    In this Report, we present a record-high-peak-power single-frequency master oscillator power amplifier (MOPA) system based on a newly developed double-clad large-mode-area Yb-free Er-doped fiber (DC-LMA-EDF). A fiber Bragg grating wavelength-stabilized fiber-coupled diode laser at λ=1551 nm with ~2 MHz spectral width was used as the master oscillator. Its radiation was externally modulated with a 5 kHz repetition rate and 92 ns pulse duration and then amplified in a core-pumped Er-doped fiber amplifier up to an average power of 4 mW. The amplified spontaneous emission (ASE) generated at the last preamplifier stage was suppressed by a narrow-band (0.7 nm) DWDM filter. The last MOPA stage was based on the recently developed single-mode DC-LMA-EDF with a mode field diameter of 25 microns and pump clad-absorption of 3 dB/m at λ=980 nm. The pump and the signal were launched into this fiber through a commercial pump combiner in a co-propagating amplifier scheme. At first, we used a 3-m long DC-LMAEDF. In such configuration, a peak power of 800 W was achieved at the output of the amplifier together with a ~ 12 % pump conversion slope efficiency. Further power scaling was limited by SBS. After that we shortened the fiber length to 1 m. As a result, owing to large unabsorbed pump power, the efficiency decreased to ~5 %. However, a peak power of more than 3.5 kW was obtained before the SBS threshold. In this case, the pulse shape changed and its duration decreased to ~60 ns owing to inversion depletion after propagation of the forward front of the pulse. To the best of our knowledge, the peak power of more than 3.5 kW reported here is the highest value ever published for a single-frequency single-mode silica-based fiber laser system operating near λ=1550 nm.

  2. High peak-power laser system tuneable from 8 to 10 μm

    NASA Astrophysics Data System (ADS)

    Gutty, François; Grisard, Arnaud; Larat, Christian; Papillon, Dominique; Schwarz, Muriel; Gérard, Bruno; Ostendorf, Ralf; Wagner, Joachim; Lallier, Eric

    2017-04-01

    A high peak-power rapidly tuneable laser system in the long-wave infrared is obtained using an external cavity quantum-cascade laser (EC-QCL) broadly tuneable from 8 to 10 μm and an optical parametric amplifier (OPA) based on quasi phase-matching in orientation-patterned gallium arsenide (OP-GaAs). To provide an efficient amplification, the nonlinear crystal is pumped by a pulsed fiber laser source. With a pump laser source tuneable around 2 μm, quasi phase-matching remains satisfied with a fixed grating period in the OP-GaAs crystal when the EC-QCL wavelength is swept from 8 to 10 μm. The OPA demonstrates parametric amplification from 8 to 10 μm and achieves output peak powers up to 140 W, with spectral linewidths below 3.5 cm-1 and a beam profile quality (M2) below 3.4 in both horizontal and vertical directions.

  3. High peak-power kilohertz laser system employing single-stage multi-pass amplification

    DOEpatents

    Shan, Bing; Wang, Chun; Chang, Zenghu

    2006-05-23

    The present invention describes a technique for achieving high peak power output in a laser employing single-stage, multi-pass amplification. High gain is achieved by employing a very small "seed" beam diameter in gain medium, and maintaining the small beam diameter for multiple high-gain pre-amplification passes through a pumped gain medium, then leading the beam out of the amplifier cavity, changing the beam diameter and sending it back to the amplifier cavity for additional, high-power amplification passes through the gain medium. In these power amplification passes, the beam diameter in gain medium is increased and carefully matched to the pump laser's beam diameter for high efficiency extraction of energy from the pumped gain medium. A method of "grooming" the beam by means of a far-field spatial filter in the process of changing the beam size within the single-stage amplifier is also described.

  4. Design and cold testing of a high peak power x-band gyroklystron

    SciTech Connect

    Lawson, W.; Calame, J.; Granatstein, V.L.; Latham, P.E.; McAdoo, J.; Park, G.S.; Striffler, C.D.; Williams, F.J.; Chu, K.R.; Seftor, J.L.

    1985-01-01

    The main goal of the University of Maryland's gyroklystron project is to develop an efficient, high power, high gain, phase controllable amplifier at 10 GHz. While peak powers of several hundred megawatts are ultimately of interest, our initial experimental design values include 30 MW of output power in 1 ..mu..s pulses with a gain in excess of 50 dB. The 30 MW power level represents an enhancement of almost three orders of magnitude over the current state-of-the-art in gyroklystron amplifiers. This enhancement will be achieved by going to high beam energies (..gamma..approx. =2) and overmoded cavities (TE/sub 01//sup 0/). Outlined in this report are the steps being taken to realize our goal.

  5. High peak power (≥10 mW) quantum cascade superluminescent emitter

    SciTech Connect

    Aung, Nyan L. Yu, Zhouchangwan; Yu, Ye; Liu, Peter Q.; Gmachl, Claire F.; Wang, Xiaojun; Fan, Jen-Yu; Troccoli, Mariano

    2014-12-01

    We report room temperature and milliwatt range mid-infrared superluminescent emission at 5 μm from Quantum Cascade (QC) devices. To achieve high power superluminescence, we utilize an ultrastrong coupling QC laser design, and employ a cavity formed by the combination of a 17° tilted cleaved facet and a wet etched rounded and sloped facet to introduce additional mirror loss. For pulsed mode operation, a 8 mm long and 15 μm wide device achieves ∼1.3 mW peak power at 300 K and a 25 μm wide device with Si{sub 3}N{sub 4} anti-reflection coated rounded facet achieves ∼10.2 mW peak optical output power at 250 K.

  6. A torque controlled high speed flywheel energy storage system for peak power transfer in electric vehicles

    SciTech Connect

    Schaible, U.; Szabados, B.

    1994-12-31

    This paper provides a design outline and implementation procedure for a flywheel energy storage system using a high speed interior permanent magnet synchronous machine, torque-controlled through the use of a vector control algorithm. The proposed flywheel energy storage system can be used to meet the peak energy requirements of an electric vehicle during both acceleration and regenerative braking. By supplying the peak energy requirements from a secondary source, the life cycle of the electric vehicle`s batteries may be extended considerably. A torque control algorithm is presented and preliminary implementation through a commercially available microcontroller is described. Preliminary testing of the proposed system has been very promising and has proven that bidirectional peak power transfer can be rapidly accomplished. 4 refs.

  7. Efficient high-peak-power and high-repetition-rate eye-safe laser using an intracavity KTP OPO

    NASA Astrophysics Data System (ADS)

    Guo, J.; He, G. Y.; Jiao, Z. X.; Wang, B.

    2015-03-01

    An efficient high-peak-power and high-repetition-rate intracavity KTP optical parametric oscillator pumped by a Q-switched Nd:YVO4 laser is demonstrated. We achieved 1.5 W output power of 1.5 μm at 10 kHz repetition rate with the pulse duration of 6 ns. The maximum peak power of 25 kW and the maximum pulse energy of 150 μJ have been obtained. The maximum conversion efficiency of 9.5% is achieved with respect to a laser diode power of 10.5 W.

  8. Single-shot measurement of >1010 pulse contrast for ultra-high peak-power lasers

    NASA Astrophysics Data System (ADS)

    Wang, Yongzhi; Ma, Jingui; Wang, Jing; Yuan, Peng; Xie, Guoqiang; Ge, Xulei; Liu, Feng; Yuan, Xiaohui; Zhu, Heyuan; Qian, Liejia

    2014-01-01

    Real-time pulse-contrast observation with a high dynamic range is a prerequisite to tackle the contrast challenge in ultra-high peak-power lasers. However, the commonly used delay-scanning cross-correlator (DSCC) can only provide the time-consumed measurements for repetitive lasers. Single-shot cross-correlator (SSCC) becomes essential in optimizing laser systems and exploring contrast mechanisms. Here we report our progress in developing SSCC towards its practical use. By integrating both the techniques of scattering-noise reduction and sensitive parallel detection into SSCC, we demonstrate a high dynamic range of >1010, which, to our best knowledge, is the first demonstration of an SSCC with a dynamic range comparable to that of commercial DSCCs. The comparison of high-dynamic measurement performances between SSCC and a standard DSCC (Sequoia, Amplitude Technologies) is also carried out on a 200 TW Ti:sapphire laser, and the consistency of results verifies the veracity of our SSCC.

  9. Single-shot measurement of >1010 pulse contrast for ultra-high peak-power lasers

    PubMed Central

    Wang, Yongzhi; Ma, Jingui; Wang, Jing; Yuan, Peng; Xie, Guoqiang; Ge, Xulei; Liu, Feng; Yuan, Xiaohui; Zhu, Heyuan; Qian, Liejia

    2014-01-01

    Real-time pulse-contrast observation with a high dynamic range is a prerequisite to tackle the contrast challenge in ultra-high peak-power lasers. However, the commonly used delay-scanning cross-correlator (DSCC) can only provide the time-consumed measurements for repetitive lasers. Single-shot cross-correlator (SSCC) becomes essential in optimizing laser systems and exploring contrast mechanisms. Here we report our progress in developing SSCC towards its practical use. By integrating both the techniques of scattering-noise reduction and sensitive parallel detection into SSCC, we demonstrate a high dynamic range of >1010, which, to our best knowledge, is the first demonstration of an SSCC with a dynamic range comparable to that of commercial DSCCs. The comparison of high-dynamic measurement performances between SSCC and a standard DSCC (Sequoia, Amplitude Technologies) is also carried out on a 200 TW Ti:sapphire laser, and the consistency of results verifies the veracity of our SSCC. PMID:24448655

  10. Single and dual-chip high peak-power semiconductor laser

    NASA Astrophysics Data System (ADS)

    Myers, Joshua; Kokoczka, Christopher; Cook, Gary; Bedford, Robert

    2017-05-01

    To date high power, high energy pulses in the few ns rage have been unobtainable in semiconductor lasers due to the short carrier lifetime and long cavity buildup times. In this paper we show a wavelength and pulse-width tunable semiconductor laser that is able to achieve pulses in the range of a few ns at power levels above 1 kW leading to several μJ pulse energies. This was done by inserting a polarizing beam splitter (PBS) and a λ/4 Pockels Cell (PC) into the cavity of a vertical external cavity surface emitting laser (VECSEL) allowing access to the high energy stored in the VECSEL cavity. The PC is used to electronically control the cavity polarization and with proper tailoring, all the photons built up within the cavity may be completely dumped within a single photon round trip. After this the PC is switched off and the light in the cavity is allowed to build up once again. Once the light has built back up, the VECSEL is ready to be dumped again. This has been demonstrated in both single gain chip and dual gain chip setups. We record a maximum pulse energy of 7.78 μJ and peak power of 1.7 kW at a wavelength of 1019 nm with a tunability of 16 nm.

  11. High peak power ultrafast Cr:ZnSe oscillator and power amplifier

    NASA Astrophysics Data System (ADS)

    Slobodchikov, Evgeny; Chieffo, Logan R.; Wall, Kevin F.

    2016-03-01

    Q-Peak Inc. has developed a Cr:ZnSe based femtosecond oscillator - power amplifier laser operating in the 2.5-μm region. The system generates 1 mJ per pulse at a 1-kHz repetition rate with a pulse duration of 184 fs, corresponding to a peak power of 5 GW. To the best of our knowledge this represents a record power for this spectral region. The highpeak power source utilizes a hybrid laser architecture, combining efficient fiber-laser pumping with solid state crystals. A Tm:fiber laser pumped, SESAM-initiated, Cr:ZnSe femtosecond oscillator provides a seed for chirped pulse amplification. The oscillator outputs 50-fs pulses that are stretched in a grating pulse stretcher and then amplified in a chain consisting of a regenerative amplifier and two stages of linear amplifiers all based on Cr:ZnSe. The pump power for amplification is provided by a Q-switched, high repetition rate, Ho:YLF laser, which in turn, is pumped by a high power Tm:fiber laser. The amplified pulses are compressed by a grating pulse compressor, resulting in 1 W of average power at a 1-kHz repetition rate. This laser system represents the state-of-the-art in short-pulse duration, pulse energy, and beam quality in this IR spectral range.

  12. Electron-Beam Switches For A High Peak Power Sled-II Pulse Compressor

    SciTech Connect

    Hirshfield, Jay, L.

    2015-12-02

    Omega-P demonstrated triggered electron-beam switches on the L=2 m dual-delay-line X-band pulse compressor at Naval Research Laboratory (NRL). In those experiments, with input pulses of up to 9 MW from the Omega-P/NRL X-band magnicon, output pulses having peak powers of 140-165 MW and durations of 16-20 ns were produced, with record peak power gains M of 18-20. Switch designs are described based on the successful results that should be suitable for use with the existing SLAC SLED-II delay line system, to demonstrate C=9, M=7, and n>>78%, yielding 173ns compressed pulses with peak powers up to 350MW with input of a single 50-MW.

  13. Cellular effects of acute exposure to high peak power microwave systems: Morphology and toxicology.

    PubMed

    Ibey, Bennett L; Roth, Caleb C; Ledwig, Patrick B; Payne, Jason A; Amato, Alayna L; Dalzell, Danielle R; Bernhard, Joshua A; Doroski, Michael W; Mylacraine, Kevin S; Seaman, Ronald L; Nelson, Gregory S; Woods, Clifford W

    2016-03-15

    Electric fields produced by advanced pulsed microwave transmitter technology now readily exceed the Institute of Electrical and Electronic Engineers (IEEE) C.95.1 peak E-field limit of 100 kV/m, highlighting a need for scientific validation of such a specific limit. Toward this goal, we exposed Jurkat Clone E-6 human lymphocyte preparations to 20 high peak power microwave (HPPM) pulses (120 ns duration) with a mean peak amplitude of 2.3 MV/m and standard deviation of 0.1 with the electric field at cells predicted to range from 0.46 to 2.7 MV/m, well in excess of current standard limit. We observed that membrane integrity and cell morphology remained unchanged 4 h after exposure and cell survival 24 h after exposure was not statistically different from sham exposure or control samples. Using flow cytometry to analyze membrane disruption and morphological changes per exposed cell, no changes were observed in HPPM-exposed samples. Current IEEE C95.1-2005 standards for pulsed radiofrequency exposure limits peak electric field to 100 kV/m for pulses shorter than 100 ms [IEEE (1995) PC95.1-Standard for Safety Levels with Respect to Human Exposure to Electric, Magnetic and Electromagnetic Fields, 0 Hz to 300 GHz, Institute of Electrical and Electronic Engineers: Piscataway, NJ, USA]. This may impose large exclusion zones that limit HPPM technology use. In this study, we offer evidence that maximum permissible exposure of 100 kV/m for peak electric field may be unnecessarily restrictive for HPPM devices. Bioelectromagnetics. © 2016 Wiley Periodicals, Inc.

  14. A simple sub-nanosecond ultraviolet light pulse generator with high repetition rate and peak power.

    PubMed

    Binh, P H; Trong, V D; Renucci, P; Marie, X

    2013-08-01

    We present a simple ultraviolet sub-nanosecond pulse generator using commercial ultraviolet light-emitting diodes with peak emission wavelengths of 290 nm, 318 nm, 338 nm, and 405 nm. The generator is based on step recovery diode, short-circuited transmission line, and current-shaping circuit. The narrowest pulses achieved have 630 ps full width at half maximum at repetition rate of 80 MHz. Optical pulse power in the range of several hundreds of microwatts depends on the applied bias voltage. The bias voltage dependences of the output optical pulse width and peak power are analysed and discussed. Compared to commercial UV sub-nanosecond generators, the proposed generator can produce much higher pulse repetition rate and peak power.

  15. High peak-power fiber laser based on a non filamented-core fully-aperiodic large pitch fiber

    NASA Astrophysics Data System (ADS)

    Benoit, A.; Malleville, M. A.; Du Jeu, R.; Dauliat, R.; Darwich, D.; Jamier, R.; Grimm, S.; Kobelke, Jens; Schuster, K.; Roy, P.

    2017-02-01

    In this communication, the authors report on the first high peak-power emission obtained using a solid non-filamented core fully-aperiodic large pitch fiber manufactured by the REPUSIL method which is based on the sintering and vitrification of micrometric doped silica powders. Using a simple amplifier stage based on a 75 cm long piece of a fullyaperiodic large pitch fiber with a fiber core of 50 μm, an average output power of 95 W was achieved with an available pump power of 175 W, corresponding to an optical-to-optical efficiency of 54 %. The peak power reaches about 35 kW for pulse duration of 200 ps at a repetition rate of 13.5 MHz. A recent evolution of our set-up using a seeder delivering an average power of 4 W at 1 MHz with a pulse duration of 50 ps led to the emission of 71.4W in average power corresponding to a peak power of 1.42 MW. These results present the first demonstration of high average and high peak power in pulsed regime for these fibers.

  16. High-peak-power, high-repetition-rate LD end-pumped Nd:YVO4 burst mode laser

    NASA Astrophysics Data System (ADS)

    Pan, Hu; Yan, Renpeng; Fa, Xin; Yu, Xin; Ma, Yufei; Fan, Rongwei; Li, Xudong; Chen, Deying; Zhou, Zhongxiang

    2016-06-01

    A compact high-peak-power, high-repetition-rate burst mode laser is achieved by an acousto-optical Q-switched Nd:YVO4 1064 nm laser directly pumped at 878.6 nm. Pulse trains with 10-100 pulses are obtained using acousto-optical Q-switch at repetition rates of 10-100 kHz under a pulsed pumping with a 1 ms duration. At the maximum pump energy of 108.5 mJ, the pulse energy of 10 kHz burst mode laser reaches 44 mJ corresponding to a single pulse energy of 4.4 mJ and an optical-to-optical efficiency of 40.5 %.The maximum peak power of ~468.1 kW at 10 kHz is obtained with a pulse width of 9.4 ns. The beam quality factor is measured to be M 2 ~1.5 and the pulse jitter is estimated to be less than 1 % in both amplitude and time region.

  17. Dynamic and static concept of laser-thyristor for high-peak power lasing

    NASA Astrophysics Data System (ADS)

    Slipchenko, Sergey; Podoskin, Alexsandr; Pikhtin, Nikita; Yuferev, Valentin; Tarasov, Ilya

    2015-03-01

    The model of a new type of high-power laser light generators, based on epitaxially and functionally integrated fast highpower current switch and laser heterostructure, the so-called laser-thyristor, has been developed. In this model, the functional characteristics of the laser-thyristor were analyzed by considering the epitaxially integrated structure as an optoelectronic pair constituted by a heterophototransistor and a laser diode. It was demonstrated that the turn-on of lasing fundamentally affects the injection efficiency of the laser-thyristor. The dynamic characteristics of the laser-thyristor were examined by using analytical relations for the optical feedback. It is shown that the impact ionization can substantially raise the build-up rate of the through current across the laser-thyristor structure and, as a result, make shorter the leading edge of a laser pulse. It is demonstrated that the developed dynamic model is in good agreement with experimental results at the maximum blocking voltages.

  18. High peak power miniature Yb:CNGG disordered crystal laser end-pumped by a 935-nm diode

    NASA Astrophysics Data System (ADS)

    Dai, Qibiao; Yi, Hongying; Chen, Xiaowen; Han, Wenjuan; Zhang, Huaijin; Wang, Shiwu; Liu, Junhai

    2014-04-01

    We report on an efficient miniature Yb:CNGG disordered crystal laser, which is passively Q-switched with a Cr4+:YAG crystal plate acting as saturable absorber. An average output power of 1.35 W is generated at a pulse repetition rate of 5.55 kHz with a slope efficiency of 42%; the resulting laser pulse energy and duration are respectively 243 μJ and 3.0 ns, while the peak power is as high as 81 kW.

  19. Hollow fiber optics with improved durability for high-peak-power pulses of Q-switched Nd:YAG lasers.

    PubMed

    Matsuura, Yuji; Tsuchiuchi, Akio; Noguchi, Hiroshi; Miyagi, Mitsunobu

    2007-03-10

    To improve the damage threshold of hollow optical waveguides for transmitting Q-switched Nd:YAG laser pulses, we optimize the metallization processes for the inner coating of fibers. For silver-coated hollow fiber as the base, second, and third Nd:YAG lasers, drying silver films at a moderate temperature and with inert gas flow is found to be effective. By using this drying process, the resistance to high-peak-power optical pulse radiation is drastically improved for fibers fabricated with and without the sensitizing process. The maximum peak power transmitted in the fiber is greater than 20 MW. To improve the energy threshold of aluminum-coated hollow fibers for the fourth and fifth harmonics of Nd:YAG lasers, a thin silver film is added between the aluminum film and the glass substrate to increase adhesion of the aluminum coating. By using this primer layer, the power threshold improves to 3 MW for the fourth harmonics of a Q-switched Nd:YAG laser light.

  20. High Peak Power Ka-Band Gyrotron Oscillator Experiments with Slotted and Unslotted Cavities.

    DTIC Science & Technology

    1987-11-10

    822, 1986. [4) N.S. Ginzburg, V.I. Krementsov, M.I. Petelin , P.S. Strelkov, and A.G. Shkvarunets, "Cyclotron-resonance maser with a high-current...Krementsov, M.I. Petelin , P.S. Strelkov, and A.K. Shkvarunets, "Experimental investigation of a high-current relativistic cyclotron maser," Zh. Tekh

  1. Myosin light chain phosphorylation is required for peak power output of mouse fast skeletal muscle in vitro.

    PubMed

    Bowslaugh, Joshua; Gittings, William; Vandenboom, Rene

    2016-11-01

    The skeletal myosin light chain kinase (skMLCK) catalyzed phosphorylation of the myosin regulatory light chain (RLC) is associated with potentiation of force, work, and power in rodent fast twitch muscle. The purpose of this study was to compare concentric responses of EDL from wild-type (WT) and skMLCK devoid (skMLCK(-/-)) muscles at a range of shortening speeds (0.05 to 0.70 V max) around that expected to produce maximal power (in vitro, 25 °C) both before (unpotentiated) and after (potentiated) a potentiating stimulus (PS). When collapsed across all speeds tested, neither unpotentiated force, work, or power differed between genotypes (all data n = 10, P < 0.05). In contrast, although both genotypes displayed speed-dependent increases, these increases were greater for WT than skMLCK(-/-) muscles. For example, when collapsed across the six fastest speeds we tested, both concentric force and power were increased 30-34 % in WT but only 15-17 % in skMLCK(-/-) muscles. In contrast, at the two slowest speeds, these parameters were increased in WT but decreased in skMLCK(-/-) muscles (8-10 and 7-9 %, respectively). Intriguingly, potentiation of concentric force and power was optimal near speeds producing maximal power in both genotypes. Because the PS elevated RLC phosphorylation above resting levels in WT but not in skMLCK(-/-) muscles, our data suggest that skMLCK-catalyzed phosphorylation of the RLC is required for maximal concentric power output of mouse EDL muscle stimulated at high frequency in vitro.

  2. The ultrafast high-peak power lasers in future biomedical and medical x-ray imaging

    NASA Astrophysics Data System (ADS)

    Kieffer, J. C.; Fourmaux, S.; Krol, A.

    2016-01-01

    This paper reviews recent progresses in ultrafast laser-based X-ray sources and their potential applications to high throughput X-ray imaging. Prospects for the utilization of X-rays sources related to the Laser Wakefield electron Acceleration (LWFA) are more specifically discussed with emphasis on application in diagnostic radiology.

  3. High-peak-power tunable laser operation of Yb:SrF2.

    PubMed

    Siebold, Mathias; Hein, Joachim; Kaluza, Malte Christoph; Uecker, Reinhard

    2007-07-01

    Growth, spectroscopic properties, and laser performance of Yb:SrF(2) crystals have been investigated. In spatial multimode operation of a diode-pumped Yb:SrF(2) laser a slope efficiency of 46% was measured. 180W output power with high beam quality at a pulse duration of 1.5ms was achieved by installing a mode cleaning aperture. A maximum average output power of 270mW and a tuning range of 73nm was observed.

  4. Spatial filter with volume gratings for high-peak-power multistage laser amplifiers

    NASA Astrophysics Data System (ADS)

    Tan, Yi-zhou; Yang, Yi-sheng; Zheng, Guang-wei; Shen, Ben-jian; Pan, Heng-yue; Liu, Li

    2010-08-01

    The regular spatial filters comprised of lens and pinhole are essential component in high power laser systems, such as lasers for inertial confinement fusion, nonlinear optical technology and directed-energy weapon. On the other hand the pinhole is treated as a bottleneck of high power laser due to harmful plasma created by the focusing beam. In this paper we present a spatial filter based on angular selectivity of Bragg diffraction grating to avoid the harmful focusing effect in the traditional pinhole filter. A spatial filter consisted of volume phase gratings in two-pass amplifier cavity were reported. Two-dimensional filter was proposed by using single Pi-phase-shifted Bragg grating, numerical simulation results shown that its angular spectrum bandwidth can be less than 160urad. The angular selectivity of photo-thermorefractive glass and RUGATE film filters, construction stability, thermal stability and the effects of misalignments of gratings on the diffraction efficiencies under high-pulse-energy laser operating condition are discussed.

  5. Development of robust multilayer optics for use in high-peak power radiation environments

    SciTech Connect

    MacGowan, B.J.; Mrowka, S.; Barbee, T.W. Jr.; Da Silva, L.B.; Eder, D.C.; Koch, J.A.; Turner, J.A.; Underwood, J.H.

    1993-07-27

    In many applications, x-ray multilayer mirrors are exposed to high peak fluxes of x-rays with subsequent damage to the mirror. Mirror damage is a particularly severe problem with the use of multilayers as cavity optics for short wavelength x-ray lasers. Intense optical and x-ray radiation, from the x-ray laser plasma amplifier, often damage the multilayer mirror on time scales of hundreds of picoseconds. The phenomenon of multilayer mirror damage by pulsed x-ray emission has been studied using short duration (500 psec) bursts of soft x-rays 1 from a laser produced gold plasma. The results of the experiments will be compared with some simple models and the possibility of increasing the damage thresholds of short wavelength multilayer mirrors will be discussed.

  6. Fiber-optic delivery of high-peak-power Q-switched laser pulses for in-cylinder flow measurement.

    PubMed

    Stephens, Timothy J; Haste, Martin J; Towers, David P; Thomson, Martin J; Taghizadeh, Mohammed R; Jones, Julian D C; Hand, Duncan P

    2003-07-20

    A bundle of optical fibers was constructed to deliver Q-switched frequency-doubled Nd:YAG laser pulses for the purpose of particle image velocimetry. Data loss that is due to fiber speckle was reduced by ensuring that each fiber was different in length by more than the coherence length of the laser being delivered. Hence, their speckle patterns will overlap but not interfere, producing more even illumination that is shown to reduce data loss. A custom-made diffractive optical element and careful endface preparation help to reduce damage to the fibers by the required high peak powers. With this method, pulse energies in excess of 25 mJ were delivered for a series of experimental trials within the cylinder head of an optically accessed internal combustion engine. Results from these trials are presented along with a comparison of measurements generated by conventionally delivered beams.

  7. Fiber-optic delivery of high-peak-power Q-switched laser pulses for in-cylinder flow measurement

    NASA Astrophysics Data System (ADS)

    Stephens, Timothy J.; Haste, Martin J.; Towers, David P.; Thomson, Martin J.; Taghizadeh, Mohammed R.; Jones, Julian D. C.; Hand, Duncan P.

    2003-07-01

    A bundle of optical fibers was constructed to deliver Q-switched frequency-doubled Nd:YAG laser pulses for the purpose of particle image velocimetry. Data loss that is due to fiber speckle was reduced by ensuring that each fiber was different in length by more than the coherence length of the laser being delivered. Hence, their speckle patterns will overlap but not interfere, producing more even illumination that is shown to reduce data loss. A custom-made diffractive optical element and careful endface preparation help to reduce damage to the fibers by the required high peak powers. With this method, pulse energies in excess of 25 mJ were delivered for a series of experimental trials within the cylinder head of an optically accessed internal combustion engine. Results from these trials are presented along with a comparison of measurements generated by conventionally delivered beams.

  8. Multi-point scanning two-photon excitation microscopy by utilizing a high-peak-power 1042-nm laser.

    PubMed

    Otomo, Kohei; Hibi, Terumasa; Murata, Takashi; Watanabe, Hirotaka; Kawakami, Ryosuke; Nakayama, Hiroshi; Hasebe, Mitsuyasu; Nemoto, Tomomi

    2015-01-01

    The temporal resolution of a two-photon excitation laser scanning microscopy (TPLSM) system is limited by the excitation laser beam's scanning speed. To improve the temporal resolution, the TPLSM system is equipped with a spinning-disk confocal scanning unit. However, the insufficient energy of a conventional Ti:sapphire laser source restricts the field of view (FOV) for TPLSM images to a narrow region. Therefore, we introduced a high-peak-power Yb-based laser in order to enlarge the FOV. This system provided three-dimensional imaging of a sufficiently deep and wide region of fixed mouse brain slices, clear four-dimensional imaging of actin dynamics in live mammalian cells and microtubule dynamics during mitosis and cytokinesis in live plant cells.

  9. No detectable bioeffects following acute exposure to high peak power ultra-wide band electromagnetic radiation in rats.

    PubMed

    Walters, T J; Mason, P A; Sherry, C J; Steffen, C; Merritt, J H

    1995-06-01

    A wide range assessment of the possible bioeffects of an acute exposure to high peak power ultra-wide band (UWB) electromagnetic radiation was performed in rats. The UWB-exposure consisted of 2 min of pulsed (frequency: 60 Hz, pulse width: 5-10 ns) UWB (bandwidth: 0.25-2.50 GHz) electromagnetic radiation. Rats were examined using one of the following: 1) a functional observational battery (FOB); 2) a swimming performance test; 3) a complete panel of blood chemistries; or 4) determination of the expression of the c-fos protein in immunohistologically-stained sections of the brain. No significant differences were found between UWB- or sham-exposed rats on any of the measured parameters.

  10. [Thermoelastic excitation of acoustic waves in biological models under the effect of the high peak-power pulsed electromagnetic radiation of extremely high frequency].

    PubMed

    Gapeev, A B; Rubanik, A V; Pashovkin, T N; Chemeris, N K

    2007-01-01

    The capability of high peak-power pulsed electromagnetic radiation of extremely high frequency (35,27 GHz, pulse widths of 100 and 600 ns, peak power of 20 kW) to excite acoustic waves in model water-containing objects and muscular tissue of animals has been experimentally shown for the first time. The amplitude and duration of excited acoustic pulses are within the limits of accuracy of theoretical assessments and have a complex nonlinear dependence on the energy input of electromagnetic radiation supplied. The velocity of propagation of acoustic pulses in water-containing models and isolated muscular tissue of animals was close to the reference data. The excitation of acoustic waves in biological systems under the action of high peak-power pulsed electromagnetic radiation of extremely high frequency is the important phenomenon, which essentially contributes to the understanding of the mechanisms of biological effects of these electromagnetic fields.

  11. High peak power continuum generation by high-order solitons at the mid-infrared wavelength in a photonic crystal fiber

    NASA Astrophysics Data System (ADS)

    Yuan, Jinhui; Zhou, Guiyao; Liu, Hongzhan; Xia, Changming; Sang, Xinzhu; Yu, Chongxiu; Wang, Kuiru; Yan, Binbin; Han, Ying; Hou, Lantian

    2015-04-01

    A photonic crystal fiber (PCF) is fabricated from silica material purified by the complexing method of rectification and adsorption in our laboratory. The parameters of pump pulses and fiber length are optimized in the experiment, and the nonlinear optical process of the high-order soliton generation is studied. The high peak power continuums at the mid-infrared wavelength are generated by the overlap among the high-order soliton peaks. Specifically, when a PCF with a length of 60 cm is used, the conversion efficiency η and bandwidth B of the continuum generated can be up to 65% and 358 nm, and the corresponding peak power Ppeak-o and pulse width Wp are 144 kW and 30 fs. It is believed that the high peak power and broadband mid-infrared continuum can be used as short pulse sources, which will find important applications in biophotonics and ultrafast science and technology.

  12. Immediate post-exposure effects of high-peak-power microwave pulses on operant behavior of Wistar rats

    SciTech Connect

    Akyel, Y.; Hunt, E.L.; Gambrill, C.; Vargas, C. Jr. )

    1991-01-01

    Behavioral effects of high-peak-power microwave pulses on Wistar rats were studied by operant schedules. Each of twelve rats that had been trained to press a lever to receive food pellets was assigned randomly in groups of four to three different schedules of reinforcement: fixed-ratio (FR), variable-interval (VI), and differential-reinforcement-of-low-rates (DRL). After achieving a steady baseline performance, each animal was exposed for 10 min to 1.25-GHz microwave radiation at 1-MW peak-power (10-microseconds pulse width). Each pulse produced a peak whole-body SA and SAR of 2.1 J/kg and 0.21 MW/kg. Total doses (SAs) were set to 0.50, 1.5, 4.5, and 14 kJ/kg by adjusting the pulse-repetition rate. The corresponding time-averaged whole-body SARs were 0.84, 2.5, 7.6, and 23 W/kg. A microwave-transparent animal holder was used to keep the animal's body axis parallel to the E-field. Exposures at the highest dose caused an average colonic temperature rise of 2.5C and these animals failed to respond at all for about 13 minutes after the exposure. Their colonic temperatures had decreased to 1.1C, or less, above their pre-exposure (normal) temperature level when they began to respond. The FR and VI animals failed to reach their baseline levels of performance thereafter, while those on the DRL schedule displayed variable effects. No behavioral effects were found at the lower dose levels. It is concluded that the behavioral perturbations produced by pulsed microwave irradiation were thermal in nature.

  13. Peak power tunable mid-infrared oscillator pumped by a high power picosecond pulsed fiber amplifier with bunch output

    NASA Astrophysics Data System (ADS)

    Wei, Kaihua; Guo, Yan; Lai, Xiaomin; Fan, Shanhui

    2016-07-01

    A high power mid-infrared optical parametric oscillator (OPO) with picosecond pulse bunch output is experimentally demonstrated. The pump source was a high power master oscillation power amplifier (MOPA) picosecond pulsed fiber amplifier. The seed of the MOPA was a gain-switched distributed Bragg reflector (DBR) laser diode (LD) with picosecond pulse operation at a high repetition rate. The seed laser was amplified to 50 W by two-stage pre-amplifiers and a large mode area (LMA) Yb fiber based power-amplifier. A fiber-pigtailed acousto-optic modulator with the first order diffraction transmission was inserted into the second pre-amplifier to form a picosecond pulse bunch train and to change the peak power simultaneously. The power-amplified pulse bunches were focused to pump a wavelength-tunable OPO for emitting high power mid-infrared laser. By adjusting the OPO cavity length, the maximum average idler powers obtained at 3.1, 3.3 and 3.5 μm were 7, 6.6 and 6.4 W respectively.

  14. Recent developments in widely tunable and high peak power ultrafast laser sources and their adoption in biological imaging

    NASA Astrophysics Data System (ADS)

    Klein, J.

    2016-03-01

    Widely tunable ultrafast lasers have enabled a large number of biological imaging techniques including point scanning multiphoton excited fluorescence (MPEF), SHG/THG and stimulated Raman imaging. Tunable ultrafast lasers offer spectral agility, covering the entire relative transparency window in live tissue (700-1300nnm) and flexibility with multi-color, synchronized outputs to support sophisticated label free techniques (e.g. stimulated Raman modalities). More recently newly available high peak power lasers based on Ytterbium technology drive advances in two-photon light-sheet, 3 photon excited fluorescence and holographic patterning for optogenetics photo-stimulation. These laser platforms offer a unique blend of compactness, ease of use and cost efficiency, and ideally complement tunable platforms typically based on Ti:Sapphire and IR optical parametric oscillators (OPO). We present various types of ultrafast laser architectures, link their optical characteristics to key bio-imaging requirements, and present relevant examples and images illustrating their impact in biological science. In particular we review the use of ultrafast lasers in optogenetics for photo-stimulation of networks of neurons.

  15. Passive radio frequency peak power multiplier

    DOEpatents

    Farkas, Zoltan D.; Wilson, Perry B.

    1977-01-01

    Peak power multiplication of a radio frequency source by simultaneous charging of two high-Q resonant microwave cavities by applying the source output through a directional coupler to the cavities and then reversing the phase of the source power to the coupler, thereby permitting the power in the cavities to simultaneously discharge through the coupler to the load in combination with power from the source to apply a peak power to the load that is a multiplication of the source peak power.

  16. High peak power Q-switched Er:YAG laser with two polarizers and its ablation performance for hard dental tissues.

    PubMed

    Yang, Jingwei; Wang, Li; Wu, Xianyou; Cheng, Tingqing; Jiang, Haihe

    2014-06-30

    An electro-optically Q-switched high-energy Er:YAG laser with two polarizers is proposed. By using two Al(2)O(3) polarizing plates and a LiNbO(3) crystal with Brewster angle, the polarization efficiency is significantly improved. As a result, 226 mJ pulse energy with 62 ns pulse width is achieved at the repetition rate of 3 Hz, the corresponding peak power is 3.6 MW. To our knowledge, such a high peak power has not been reported in literature. With our designed laser, in-vitro teeth were irradiated under Q-switched and free-running modes. Results of a laser ablation experiment on hard dental tissue with the high-peak-power laser demonstrates that the Q-switched Er:YAG laser has higher ablation precision and less thermal damage than the free-running Er:YAG laser.

  17. High-peak-power, short-pulse-width, LD end-pumped, passively Q-switched Nd:YAG 946 nm laser

    NASA Astrophysics Data System (ADS)

    Yan, Renpeng; Yu, Xin; Ma, Yufei; Li, Xudong; Chen, Deying; Yu, Junhua

    2012-10-01

    High-peak-power, short-pulse-width diode pumped 946 nm Nd:YAG laser in passively Q-switching operation with Cr4+:YAG is reported. The highest average output power reaches 3.4 W using the Cr4+:YAG with initial transmissivity T0=95%. When the T0=90% Cr4+:YAG is employed, the maximum peak power of 31.4 kW with a pulse width of 8.3 ns at 946 nm is generated.

  18. Compact sources for the generation of high-peak power wavelength-stabilized laser pulses in the picoseconds and nanoseconds ranges

    NASA Astrophysics Data System (ADS)

    Wenzel, H.; Klehr, A.; Schwertfeger, S.; Liero, A.; Hoffmann, Th.; Brox, O.; Thomas, M.; Erbert, G.; Tränkle, G.

    2012-03-01

    Diode lasers are ideally suited for the generation of optical pulses in the nanoseconds and picoseconds ranges by gainswitching, Q-switching or mode-locking. We have developed diode-laser based light sources where the pulses are spectrally stabilized and nearly-diffraction limited as required by many applications. Diffraction limited emission is achieved by a several microns wide ridge waveguide (RW), so that only the fundamental lateral mode should lase. Spectral stabilization is realized with a Bragg grating integrated into the semiconductor chip, resulting in distributed feedback (DFB) or distributed Bragg reflector (DBR) lasers. We obtained a peak power of 3.8W for 4ns long pulses using a gain-switched DFB laser and a peak power of more than 4W for 65ps long pulses using a three-section DBR laser. Higher peak powers of several tens of Watts can be reached by an amplification of the pulses with semiconductor optical amplifiers, which can be either monolithically or hybrid integrated with the master oscillators. We developed compact modules with a footprint of 4×5cm2 combining master oscillator, tapered power amplifier, beam-shaping optical elements and high-frequency electronics. In order to diminish the generation of amplified spontaneous emission between the pulses, the amplifier is modulated with short-pulses of high amplitude, too. Beyond the amplifier, we obtained a peak power of more than 10W for 4ns long pulses, a peak power of about 35W for 80ps long pulses and a peak power of 70W for 10ps long pulses at emission wavelengths around 1064nm.

  19. High efficiency and high peak power picosecond mid-infrared optical parametric amplifier based on BaGa4Se7 crystal.

    PubMed

    Yang, Feng; Yao, Ji-yong; Xu, Hong-yan; Feng, Kai; Yin, Wen-long; Li, Fang-qin; Yang, Jing; Du, Shi-feng; Peng, Qin-jun; Zhang, Jing-yuan; Cui, Da-fu; Wu, Yi-cheng; Chen, Chuang-tian; Xu, Zu-yan

    2013-10-01

    A high efficiency and high peak power picosecond (ps) mid-infrared optical parametric amplifier with a new nonlinear crystal BaGa(4)Se(7) pumped by a 30 ps 1064 nm Nd:YAG laser is demonstrated for the first time. The maximum photon conversion efficiency of 56% from 1064 nm to 3.9 μm idler has been achieved at the pump energy of ~1.8 mJ. A maximum idler output of 830 μJ at 3.9 μm with peak power of ~27 MW was obtained at pump energy of ~9.1 mJ. Moreover, a 3-5 μm idler tuning range was demonstrated, with output energies of ~300 μJ at 5 μm and up to 1 mJ at 3 μm at ~8.2 mJ pump energy.

  20. High-pressure dielectric barrier discharge Xenon lamps generating short pulses of high-peak-power VUV radiation (172nm) with high pulse-to-pulse reproducibility.

    NASA Astrophysics Data System (ADS)

    Carman, Robert; Ward, Barry; Mildren, Richard; Kane, Deborah

    2003-10-01

    Dielectric barrier discharges (DBDs) are used to efficiently generate radiation in the ultraviolet and vacuum-ultraviolet spectral regions (88nm-350nm) by forming rare-gas and rare-gas halide excimers in a transient plasma. Usually, DBD lamps generate the light output quasi-continuously or in bursts with a high degree of stochastic or random variability in the instantaneous UV/VUV intensity. However, regular pulses of high-peak-power UV/VUV, with high pulse-to-pulse reproducibility, are of interest for applications in biology, surface treatment and cleaning, and time-resolved fluorescence spectroscopy. Such pulses can be generated from spatially homogeneous plasmas in a Xe DBD when the discharge is driven by uni-polar voltage pulses of short duration ( 100ns)^1. In the present study, we will report Xe DBD lamp performance and VUV output pulse characteristics for gas pressures up to 2.5bar and excitation conditions tailored for high-peak-power output. The experimental results will be compared to theoretical results from a detailed 1-D computer model of the spatio-temporal evolution of the plasma kinetics and Xe species population densities. ^1R.P.Mildren and R.J.Carman, J.Phys.D, 34, L1-L6, (2001)

  1. Two-photon bioimaging utilizing supercontinuum light generated by a high-peak-power picosecond semiconductor laser source.

    PubMed

    Yokoyama, Hiroyuki; Tsubokawa, Hiroshi; Guo, Hengchang; Shikata, Jun-ichi; Sato, Ki-ichi; Takashima, Keijiro; Kashiwagi, Kaori; Saito, Naoaki; Taniguchi, Hirokazu; Ito, Hiromasa

    2007-01-01

    We developed a novel scheme for two-photon fluorescence bioimaging. We generated supercontinuum (SC) light at wavelengths of 600 to 1200 nm with 774-nm light pulses from a compact turn-key semiconductor laser picosecond light pulse source that we developed. The supercontinuum light was sliced at around 1030- and 920-nm wavelengths and was amplified to kW-peak-power level using laboratory-made low-nonlinear-effects optical fiber amplifiers. We successfully demonstrated two-photon fluorescence bioimaging of mouse brain neurons containing green fluorescent protein (GFP).

  2. Cascaded Raman shifting of high-peak-power nanosecond pulses in As₂S₃ and As₂Se₃ optical fibers.

    PubMed

    White, Richard T; Monro, Tanya M

    2011-06-15

    We report efficient cascaded Raman scattering of near-IR nanosecond pulses in large-core (65 μm diameter) As₂S₃ and As₂Se₃ optical fibers. Raman scattering dominates other spectral broadening mechanisms, such as four-wave mixing, modulation instability, and soliton dynamics, because the fibers have large normal group-velocity dispersion in the spectral range of interest. With ~2 ns pump pulses at a wavelength of 1.9 μm, four Stokes peaks, all with peak powers greater than 1 kW, have been measured.

  3. 975nm high-peak power ns-diode laser based MOPA system suitable for water vapor DIAL applications

    NASA Astrophysics Data System (ADS)

    Sumpf, Bernd; Klehr, Andreas; Vu, Thi Nghiem; Erbert, Götz; Tränkle, Günther

    2015-03-01

    Micro-DIAL (differential absorption LIDAR) systems require light sources with peak powers in the range of several 10 W together with a spectral line width smaller than the width of absorption lines under study. For water vapor at atmospheric pressure this width should be smaller than 10 pm at 975 nm. In this paper, an all semiconductor master oscillator power amplifier system at an emission wavelength of 975 nm will be presented. This spectral range was selected with respect to a targeted absorption path length of 5000 m and H2O line strengths. A distributed feedback (DFB) ridge waveguide diode laser operated in continuous wave is used as master oscillator whereas a tapered amplifier consisting of a RW section and a flared section is implemented as power amplifier. The RW section acts as optical gate. The current pulses injected into the RW part have a length of 8 ns and the tapered part is driven with 15 ns long pulses. The delay between the pulses is adjusted for optimal pulse shape. The repetition rate is in both cases 25 kHz. A maximal pulse output power of about 16 W limited by the available current supply is achieved. The spectral line width of the system determined by the properties of the DFB laser is smaller than 10 pm. The tuning range amounts 0.9 nm and a SMSR of 40 dB is observed. From the dependence of the peak power on the power injected into the tapered amplifier, the saturation power is determined to 5.3 mW.

  4. Generation of 130 W narrow-linewidth high-peak-power picosecond pulses directly from a compact Yb-doped single-stage fiber amplifier

    NASA Astrophysics Data System (ADS)

    Qi, Yaoyao; Yu, Haijuan; Zhang, Jingyuan; Wang, Lei; Zhang, Ling; Lin, Xuechun

    2015-09-01

    We report a compact, 130-W single-stage master oscillator power amplifier with a high peak power of 51.3 kW and a narrow spectral linewidth of 0.1 nm. The seed source is a single-mode, passively mode-locked solid-state laser at 1064 nm with an average power of 2 W. At a repetition rate of 73.5 MHz, the pulse duration is 30 ps. After amplification, it stretches to 34.5 ps. The experiment enables the optical-to-optical conversion efficiency to reach 75%. To the best of our knowledge, this is the first report of such a high-power, narrow spectral linewidth, high peak power picosecond-pulse fiber amplifier based on a continuous-wave, mode-locked solid-state seeding laser. No amplified spontaneous emission and stimulated Raman scattering were observed when the pump was increased.

  5. High-peak-power low-threshold AlGaAs/GaAs stripe laser diodes on Si substrates grown by migration-enhanced molecular beam epitaxy

    NASA Technical Reports Server (NTRS)

    Kim, Jae-Hoon; Nouhi, Akbar; Radhakrishnan, Gouri; Liu, John K.; Lang, Robert J.

    1988-01-01

    A high-peak-power low-threshold AlGaAs/GaAs double-heterostructure stripe laser diode on Si substrats, grown by hybrid migration-enhanced molecular beam epitaxy (MEMBE) and metalorganic chemical vapor deposition (MOCVD) has been demonstrated for the first time. These devices showed the highest peak powers of up to 184 mW per facet reported so far for double-heterostructure stripe laser diodes on Si substrates, room-temperature pulsed threshold currents as low as 150 mA, and differential quantum efficiencies as high as 30 percent without mirror facet coating. An intrinsic threshold current density has been estimated to be about 2 kA/sq cm when taking current spreading and lateral diffusion effects into account. Low dislocation density shows that MEMBE can be a useful method to grow high-quality GaAs and AlGaAs/GaAs layers on Si substrates by combining with MOCVD.

  6. Ignition of an automobile engine by high-peak power Nd:YAG/Cr⁴⁺:YAG laser-spark devices.

    PubMed

    Pavel, Nicolaie; Dascalu, Traian; Salamu, Gabriela; Dinca, Mihai; Boicea, Niculae; Birtas, Adrian

    2015-12-28

    Laser sparks that were built with high-peak power passively Q-switched Nd:YAG/Cr(4+):YAG lasers have been used to operate a Renault automobile engine. The design of such a laser spark igniter is discussed. The Nd:YAG/Cr(4+):YAG laser delivered pulses with energy of 4 mJ and 0.8-ns duration, corresponding to pulse peak power of 5 MW. The coefficients of variability of maximum pressure (COV(Pmax)) and of indicated mean effective pressure (COV(IMEP)) and specific emissions like hydrocarbons (HC), carbon monoxide (CO), nitrogen oxides (NO(x)) and carbon dioxide (CO2) were measured at various engine speeds and high loads. Improved engine stability in terms of COV(Pmax) and COV(Pmax) and decreased emissions of CO and HC were obtained for the engine that was run by laser sparks in comparison with classical ignition by electrical spark plugs.

  7. The modified SRRS threshold criteria for high peak power laser pulses in long air-path transmission considering the near-field beam quality

    NASA Astrophysics Data System (ADS)

    Zhu, C. Y.; Lin, D. Y.; Lu, Z. W.; Wang, Y. X.; Wang, Z.; Liang, L. X.; Ba, D. X.

    2016-11-01

    This paper demonstrates that the stimulated rotational Raman scattering (SRRS) threshold for high peak power laser pulses propagating through a long air path can be influenced strongly by the near-field quality of the laser beams, and the relationship between the SRRS threshold and the near-field beam quality (i.e., spatial intensity modulation index and contrast ratio) can be evaluated quantitatively. By using our three-dimensional numerical model, which can describe the spatial-temporal evolution behaviors of SRRS and is verified by previously published SRRS experimental data, the criteria of the safe transmission distance for high peak power nanosecond laser pulses are obtained, and the modified SRRS threshold criterion formulas considering the near-field beam conditions are presented.

  8. [Dependence of anti-inflammatory effects of high peak-power pulsed electromagnetic radiation of extremely high frequency on exposure parameters].

    PubMed

    Gapeev, A B; Mikhaĭlik, E N; Rubanik, A V; Cheremis, N K

    2007-01-01

    A pronounced anti-inflammatory effect of high peak-power pulsed electromagnetic radiation of extremely high frequency was shown for the first time in a model of zymosan-induced footpad edema in mice. Exposure to radiation of specific parameters (35, 27 GHz, peak power 20 kW, pulse widths 400-600 ns, pulse repetition frequency 5-500 Hz) decreased the exudative edema and local hyperthermia by 20% compared to the control. The kinetics and the magnitude of the anti-inflammatory effect were comparable with those induced by sodium diclofenac at a dose of 3 mg/kg. It was found that the anti-inflammatory effect linearly increased with increasing pulse width at a fixed pulse repetition frequency and had threshold dependence on the average incident power density of the radiation at a fixed pulse width. When animals were whole-body exposed in the far-field zone of radiator, the optimal exposure duration was 20 min. Increasing the average incident power density upon local exposure of the inflamed paw accelerated both the development of the anti-inflammatory effect and the reactivation time. The results obtained will undoubtedly be of great importance in the hygienic standardization of pulsed electromagnetic radiation and in further studies of the mechanisms of its biological action.

  9. High-peak power, passively Q-switched, composite, all-polycrystalline ceramic Nd:YAG/Cr{sup 4+}:YAG lasers

    SciTech Connect

    Sandu, O; Salamu, G; Pavel, N; Dascalu, T; Chuchumishev, D; Gaydardzhiev, A; Buchvarov, I

    2012-03-31

    High-peak power, passively Q-switched, composite Nd : YAG/Cr{sup 4+} : YAG lasers consisting of all-polycrystalline bonded Nd:YAG and Cr{sup 4+}:YAG ceramics are developed, and two applications of such lasers are discussed. A 1.1-at. %-doped Nd:YAG/Cr{sup 4+}:YAG ceramic laser is fabricated, which is quasi-cw pumped by a diode laser in the Hz-range, delivering laser pulses of 2.5-mJ energy and 1.9-MW peak power. By frequency doubling the laser output in a LiB{sub 3}O{sub 5} (LBO) nonlinear crystal at room temperature, 0.36-mJ, 0.3-MW green laser pulses with 27 % conversion efficiency are produced at 532 nm. Furthermore, a highly doped (1.5-at. %) Nd:YAG/Cr{sup 4+}:YAG ceramic laser operates successfully in the range of pulse repetition rates from 50 to 500 Hz, yielding 0.8-to-1.0 mJ pulses with a peak power around 1 MW. The laser output beam is amplified in a master-oscillator - power-amplifier (MOPA) system to generate laser pulses with 11-mJ energy at a 250-Hz repetition rate. (lasers)

  10. High peak power, 28 ns Q-switched Tm:LuAG laser at a 2 μm wavelength by dual-loss-modulation

    NASA Astrophysics Data System (ADS)

    Luan, Chao; Yang, Kejian; Zhao, Jia; Zhao, Shengzhi; Qiao, Wenchao; Li, Tao; Liu, Cheng; Chu, Hongwei; Qiao, Junpeng; Zheng, Lihe; Xu, Xiaodong; Xu, Jun

    2016-02-01

    By employing output couplers (OCs) with different transmissions T and GaAs saturable absorbers (SAs) with different modulation depth ΔR in a passively Q-switched Tm:LuAG laser at 2 μm, the optimal parameters of OCs and SAs for obtaining short pulse width and high peak power were investigated. By inserting an electro-optical modulator (EOM) into the optimized passively Q-switched Tm:LuAG laser (T  =  2%/ΔR  =  19%), a dual-loss-modulated Q-switched Tm:LuAG laser with an EOM and GaAs was realized. The experimental results show that the dual-loss-modulated Q-switched laser can generate a shorter pulse width and higher peak power than the single-loss-modulated case. At an incident pump power of 8.4 W, the shortest pulse width achieved was 28 ns and the highest peak power reached 74 kW.

  11. High-peak-power surface high-harmonic generation at extreme ultra-violet wavelengths from a tape

    SciTech Connect

    Shaw, B. H.; Tilborg, J. van; Sokollik, T.; Schroeder, C. B.; McKinney, W. R.; Artemiev, N. A.; Yashchuk, V. V.; Gullikson, E. M.; Leemans, W. P.

    2013-07-28

    Solid-based surface high-harmonic generation from a tape is experimentally studied. By operating at mildly relativistic normalized laser strengths a{sub 0}≲0.2, harmonics up to the 17th order are efficiently produced in the coherent wake emission (CWE) regime. CWE pulse properties, such as divergence, energy, conversion efficiency, and spectrum, are investigated for various tape materials and drive laser conditions. A clear correlation between surface roughness and harmonic beam divergence is found. At the measured pulse properties for the 15th harmonic (conversion efficiency ∼6.5×10{sup −7}, divergence ∼7−15 mrad), the 100-mJ-level drive laser produces several MWs of extreme ultra-violet pulses. The spooling tape configuration enables multi-Hz operation over thousands of shots, making this source attractive as a seed to the few-Hz laser-plasma-accelerator-driven free-electron laser (FEL). Models indicate that these CWE pulses with MW level powers are sufficient for seed-induced bunching and FEL gain.

  12. High average/peak power linearly polarized all-fiber picosecond MOPA seeded by mode-locked noise-like pulses

    NASA Astrophysics Data System (ADS)

    Yu, H. L.; Ma, P. F.; Tao, R. M.; Wang, X. L.; Zhou, P.; Chen, J. B.

    2015-06-01

    The characteristics of mode-locked noise-like pulses generated from a passively mode-locked fiber oscillator are experimentally investigated. By carefully adjusting the two polarization controllers, stable mode-locked noise-like pulse emission with a high radio frequency signal/noise ratio of  >55 dB is successfully achieved, ensuring the safety and possibility of high power amplification. To investigate the amplification characteristics of such pulses, one all-fiber master oscillator power amplifier (MOPA) is built to boost the power and energy of such pulses. Amplified noise-like pulses with average output power of 423 W, repetition rate of 18.71 MHz, pulse energy of 22.61 μJ, pulse duration of 72.1 ps and peak power of 314 kW are obtained. Near diffraction-limited beam is also demonstrated with M2 factor measured at full power operation of ~1.2 in the X and Y directions. The polarization extinction ratio at output power of 183 W is measured to be ~13 dB. To the best of our knowledge, this is the first demonstration of high-power amplification of noise-like pulses and the highest peak power ever reported in all-fiber picosecond MOPAs. The temporal self-compression process of such pulses and high peak power when amplified make it an ideal pump source for generation of high-power supercontinuum. Other potential applications, such as material processing and optical coherent tomography, could also be foreseen.

  13. High brightness diode pumped Er:YAG laser system at 2.94 µm with nearly 1kW peak power

    NASA Astrophysics Data System (ADS)

    Messner, Manuel; Heinrich, Arne; Hagen, Clemens; Unterrainer, Karl

    2016-03-01

    We demonstrated a monolithic high-power diode-pumped Er:YAG laser at 2.94 μm with average output power of up to 50W and pulse energy beyond 300mJ in 400 μs pulses. The high peak power of nearly 1kW is delivered in a high quality beam (M2 < 15), maintained over a large cooling water temperature range of 18-25 °C. The improved resonator configuration allows for stable operation from 0-10% duty-cycle in contrast to prior developments showing saturation. As a first application, fiber-coupling into a 230 μm, 0.2NA GeO2-fiber with standard optics has been shown, reaching 30W average power and 200mJ pulse energy out of the fiber, only limited by the fiber..

  14. Peak power bi-directional transfer from high speed flywheel to electrical regulated bus voltage system: A practical proposal for vehicular technology

    SciTech Connect

    Szabados, B.; Schaible, U.

    1998-03-01

    This paper provides a design outline and implementation procedure for a Secondary Energy Storage Unit (SESU) that can be used to meet the peak energy requirements of an electric vehicle during both acceleration and regenerative braking. The life cycle of the electric vehicle`s batteries can be extended considerably by supplying peak energy requirements from a secondary source. A simulation study was conducted to determine the peak power and energy requirements over the SAE recommended electric vehicle test procedure. A scaled prototype SESU was built using flywheel energy storage, and tests were performed to determine the energy transfer capabilities of a flywheel coupled high speed permanent magnet synchronous machine through the proposed system`s energy storage tank. Results are presented that indicate the necessity of the energy storage tank. An evaluation of the proposed system is also included which indicates the practicality of the system when compared to conventional regenerative control techniques.

  15. Microprocessor control of power sharing and solar array peak power tracking for high power (2. 5 kW) switching power converters

    SciTech Connect

    Speer, J.H. Jr.

    1981-01-01

    A prototype system of twin power converters for solar array supplement of spacecraft power buses is described. Analog circuits are used for inner control loops and a microprocessor directs power sharing and peak power tracking. 3 refs.

  16. Supercomputations and big-data analysis in strong-field ultrafast optical physics: filamentation of high-peak-power ultrashort laser pulses

    NASA Astrophysics Data System (ADS)

    Voronin, A. A.; Panchenko, V. Ya; Zheltikov, A. M.

    2016-06-01

    High-intensity ultrashort laser pulses propagating in gas media or in condensed matter undergo complex nonlinear spatiotemporal evolution where temporal transformations of optical field waveforms are strongly coupled to an intricate beam dynamics and ultrafast field-induced ionization processes. At the level of laser peak powers orders of magnitude above the critical power of self-focusing, the beam exhibits modulation instabilities, producing random field hot spots and breaking up into multiple noise-seeded filaments. This problem is described by a (3  +  1)-dimensional nonlinear field evolution equation, which needs to be solved jointly with the equation for ultrafast ionization of a medium. Analysis of this problem, which is equivalent to solving a billion-dimensional evolution problem, is only possible by means of supercomputer simulations augmented with coordinated big-data processing of large volumes of information acquired through theory-guiding experiments and supercomputations. Here, we review the main challenges of supercomputations and big-data processing encountered in strong-field ultrafast optical physics and discuss strategies to confront these challenges.

  17. The Effect of Concurrent Plyometric Training Versus Submaximal Aerobic Cycling on Rowing Economy, Peak Power, and Performance in Male High School Rowers.

    PubMed

    Egan-Shuttler, Julian D; Edmonds, Rohan; Eddy, Cassandra; O'Neill, Veronica; Ives, Stephen J

    2017-12-01

    Plyometric training has been shown to increase muscle power, running economy, and performance in athletes. Despite its use by rowing coaches, it is unknown whether plyometrics might improve rowing economy or performance. The purpose was to determine if plyometric training, in conjunction with training on the water, would lead to improved rowing economy and performance. Eighteen male high school rowers were assigned to perform 4 weeks of either plyometric training (PLYO, n = 9) or steady-state cycling below ventilatory threshold (endurance, E, n = 9), for 30 min prior to practice on the water (matched for training volume) 3 days per week. Rowing performance was assessed through a 500-m rowing time trial (TT) and peak rowing power (RP), while rowing economy (RE) was assessed by measuring the oxygen cost over four work rates (90, 120, 150, and 180 W). Rowing economy was improved in both PLYO and E (p < 0.05). The 500-m TT performance improved significantly for PLYO (from 99.8 ± 9 s to 94.6 ± 2 s, p < 0.05) but not for E (from 98.8 ± 6 s to 98.7 ± 5 s, p > 0.05). Finally, RP was moderately higher in the PLYO group post-training (E 569 ± 75 W, PLYO 629 ± 51 W, ES = 0.66) CONCLUSIONS: In a season when the athletes performed no rowing sprint training, 4 weeks of plyometric training improved the 500-m rowing performance and moderately improved peak power. This increase in performance may have been mediated by moderate improvements in rowing power, but not economy, and warrants further investigation.

  18. Effects of a 6-Week Upper Extremity Low-Volume, High Intensity Interval Training on Oxygen Uptake, Peak Power Output and Total Exercise Time.

    PubMed

    Pinto, Nicole; Salassi, James W; Donlin, Ayla; Schroeder, Jan; Rozenek, Ralph

    2017-05-30

    The purpose of this study was to compare the effects of upper extremity (UE) high intensity interval training (HIIT) to UE continuous training (CT) when training at a similar intensity. 20 participants (mean age = 23 ± 3 yrs) were randomly assigned to either a HIIT (n = 10) or CT (n = 10) group. Participants completed a graded exercise test utilizing arm cranking prior to and following 6 wks (2 sessions · wk-1) of UE training. During sessions, HIIT performed 10 repetitions of 60 s of work at 92.3 ± 1.0% of the arm HRpeak (%aHRpeak) and 60 s of passive recovery (%aHRpeak = 73.0 ± 4.0%) yielding an average training intensity of 82.6 ± 1.5 %aHRpeak. CT exercised for 20 min. at an average intensity of 81.9 ± 2.2 %aHRpeak. Following training HIIT showed greater improvement in V[Combining Dot Above]O2peak compared to CT (Δ = 4.1 ml · min-¹ · kg-¹, 95%CI: 1.3 - 6.9 ml · min-¹ · kg-¹, p = .007). Total exercise time during the post-test GXT was also improved as a result of HIIT (Δ = 1.4 min, 95%CI: 0.4 - 2.3 min, p = .008). Both groups improved peak power output, but no difference was observed between them (Δ = 3.3 W, 95%CI: -3.3 - 9.9 W, p = .305). For a similar time investment, HIIT appeared to improve cardiopulmonary capacity and exercise time to a greater extent than CT and may be a time-efficient alternative for those who incorporate UE aerobic activity into a training program.

  19. High peak-power picosecond pulse generation at 1.26 µm using a quantum-dot-based external-cavity mode-locked laser and tapered optical amplifier.

    PubMed

    Ding, Y; Aviles-Espinosa, R; Cataluna, M A; Nikitichev, D; Ruiz, M; Tran, M; Robert, Y; Kapsalis, A; Simos, H; Mesaritakis, C; Xu, T; Bardella, P; Rossetti, M; Krestnikov, I; Livshits, D; Montrosset, Ivo; Syvridis, D; Krakowski, M; Loza-Alvarez, P; Rafailov, E

    2012-06-18

    In this paper, we present the generation of high peak-power picosecond optical pulses in the 1.26 μm spectral band from a repetition-rate-tunable quantum-dot external-cavity passively mode-locked laser (QD-ECMLL), amplified by a tapered quantum-dot semiconductor optical amplifier (QD-SOA). The laser emission wavelength was controlled through a chirped volume Bragg grating which was used as an external cavity output coupler. An average power of 208.2 mW, pulse energy of 321 pJ, and peak power of 30.3 W were achieved. Preliminary nonlinear imaging investigations indicate that this system is promising as a high peak-power pulsed light source for nonlinear bio-imaging applications across the 1.0 μm - 1.3 μm spectral range.

  20. High-peak-power sub-nanosecond intracavity KTiOPO4 optical parametric oscillator pumped by a dual-loss modulated laser with acousto-optic modulator and single-walled carbon nanotube

    NASA Astrophysics Data System (ADS)

    Qiao, Junpeng; Zhao, Shengzhi; Yang, Kejian; Zhao, Jia; Li, Guiqiu; Li, Dechun; Li, Tao; Qiao, Wenchao; Lu, Jianren; Wang, Yonggang; Chu, Hongwei; Luan, Chao

    2016-08-01

    A high-peak-power low-repetition-rate sub-nanosecond intracavity KTiOPO4 (KTP) optical parametric oscillator (OPO) pumped by a doubly Q-switched and mode-locked (QML) YVO4/Nd:YVO4 laser with an acousto-optic modulator (AOM) and a single-walled carbon nanotube saturable absorber (SWCNT-SA) has been demonstrated. A maximum output power of 373 mW at a signal wavelength of 1570 nm was obtained. The smallest pulse width, highest pulse energy, and greatest peak power of mode-locking pulses were estimated to be 119 ps, 124 µJ, and 1.04 MW, respectively, under a maximum incident pump power of 8.3 W and an AOM repetition rate of 2 kHz. This OPO operation paves a simple way to produce eye-safe laser sources at 1570 nm with low repetition rates, small pulse widths, and high peak powers.

  1. Generation of high-peak-power sub-nanosecond 650-nm-band optical pulses based on semiconductor-laser-controlling technologies

    NASA Astrophysics Data System (ADS)

    Hung, Jui-Hung; Sato, Kazuo; Fang, Yi-Cheng; Peng, Lung-Han; Nemoto, Tomomi; Yokoyama, Hiroyuki

    2017-10-01

    We have developed a method to generate sub-nanosecond 650-nm-band optical pulses. These pulses have a peak power of 40 W and a pulse energy of 13 nJ at a 1-MHz repetition rate. This technology is intended for application in stimulated-emission-depletion microscopy. Our method is based on the pulsed operation of a 1.3-µm-band semiconductor-laser optical amplifier and the second-harmonic generation of the optical pulses after amplification by a Pr-doped fiber amplifier. The resultant peak power and pulse energy of the 650-nm-band optical pulses are two orders of magnitude higher than those directly obtained from a laser diode.

  2. High peak-power mid-infrared ZnGeP₂ optical parametric oscillator pumped by a Tm:fiber master oscillator power amplifier system.

    PubMed

    Gebhardt, Martin; Gaida, Christian; Kadwani, Pankaj; Sincore, Alex; Gehlich, Nils; Jeon, Cheonha; Shah, Lawrence; Richardson, Martin

    2014-03-01

    We report on the utilization of a novel Tm:fiber laser source for mid-IR ZnGeP2 (ZGP) optical parametric oscillator (OPO) pumping. The pump laser is built in a master oscillator power-amplifier configuration delivering up to 3.36 W of polarized, diffraction limited output power with 7 ns pulse duration and 4 kHz repetition rate. This corresponds to a peak power of ∼121  kW and a pulse energy of ∼0.84  mJ. With this source, we generated 27.9 kW of total mid-IR peak power in a doubly resonant oscillator (DRO) configuration. This is, to the best of our knowledge, the highest ever demonstrated mid-IR peak power from a directly Tm:fiber laser pumped ZGP OPO. Moreover, a DRO output with about 284 μJ of total mid-IR pulse energy was demonstrated using 100 ns pump pulses. The wavelength tuning of the idler was extended to 6 μm with lower output power in another OPO experiment.

  3. Reducing Peak Power in Automated Weapon Laying

    DTIC Science & Technology

    2016-02-01

    UNCLASSIFIED UNCLASSIFIED AD-E403 AD-E403 737 Technical Report ARWSE-TR-15036 REDUCING PEAK POWER IN AUTOMATED WEAPON...PEAK POWER IN AUTOMATED WEAPON LAYING 5a. CONTRACT NUMBER 5b. GRANT NUMBER 5c. PROGRAM ELEMENT NUMBER 6. AUTHORS Joshua Stapp and...amount of time while reducing the amount of peak power required and, therefore, minimizing the forces caused by acceleration. 15. SUBJECT TERMS

  4. Composite, all-ceramics, high-peak power Nd:YAG/Cr(4+):YAG monolithic micro-laser with multiple-beam output for engine ignition.

    PubMed

    Pavel, Nicolaie; Tsunekane, Masaki; Taira, Takunori

    2011-05-09

    A passively Q-switched Nd:YAG/Cr(4+):YAG micro-laser with three-beam output was realized. A single active laser source made of a composite, all-ceramics Nd:YAG/Cr(4+):YAG monolithic cavity was pumped by three independent lines. At 5 Hz repetition rate, each line delivered laser pulses with ~2.4 mJ energy and 2.8-MW peak power. The M(2) factor of a laser beam was 3.7, and stable air breakdowns were realized. The increase of pump repetition rate up to 100 Hz improved the laser pulse energy by 6% and required ~6% increase of the pump pulse energy. Pulse timing of the laser-array beams can by adjusted by less than 5% tuning of an individual line pump energy, and therefore simultaneous multi-point ignition is possible. This kind of laser can be used for multi-point ignition of an automobile engine. © 2011 Optical Society of America

  5. 1.2 MW peak power, all-solid-state picosecond laser with a microchip laser seed and a high gain single-passing bounce geometry amplifier

    NASA Astrophysics Data System (ADS)

    Wang, Chunhua; Shen, Lifeng; Zhao, Zhiliang; Liu, Bin; Jiang, Hongbo; Chen, Jun; Liu, Chong

    2016-11-01

    A semiconductor saturable absorber mirror (SESAM) based passively Q-switched microchip Nd:YVO4 seed laser with pulse duration of 90 ps at repetition rate of 100 kHz is amplified by single-passing a Nd:YVO4 bounce amplifier with varying seed input power from 20 μW to 10 mW. The liquid pure metal greasy thermally conductive material is used to replace the traditional thin indium foil as the thermal contact material for better heat load transfer of the Nd:YVO4 bounce amplifier. Temperature distribution at the pump surface is measured by an infrared imager to compare with the numerically simulated results. A highest single-passing output power of 11.3 W is obtained for 10 mW averaged seed power, achieving a pulse peak power of ~1.25 MW and pulse energy of ~113 μJ. The beam quality is well preserved with M2 ≤1.25. The simple configuration of this bounce laser amplifier made the system flexible, robust and cost-effective, showing attractive potential for further applications.

  6. Effect of gear ratio on peak power and time to peak power in BMX cyclists.

    PubMed

    Rylands, Lee P; Roberts, Simon J; Hurst, Howard T

    2017-03-01

    The aim of this study was to ascertain if gear ratio selection would have an effect on peak power and time to peak power production in elite Bicycle Motocross (BMX) cyclists. Eight male elite BMX riders volunteered for the study. Each rider performed three, 10-s maximal sprints on an Olympic standard indoor BMX track. The riders' bicycles were fitted with a portable SRM power meter. Each rider performed the three sprints using gear ratios of 41/16, 43/16 and 45/16 tooth. The results from the 41/16 and 45/16 gear ratios were compared to the current standard 43/16 gear ratio. Statistically, significant differences were found between the gear ratios for peak power (F(2,14) = 6.448; p = .010) and peak torque (F(2,14) = 4.777; p = .026), but no significant difference was found for time to peak power (F(2,14) = 0.200; p = .821). When comparing gear ratios, the results showed a 45/16 gear ratio elicited the highest peak power,1658 ± 221 W, compared to 1436 ± 129 W and 1380 ± 56 W, for the 43/16 and 41/16 ratios, respectively. The time to peak power showed a 41/16 tooth gear ratio attained peak power in -0.01 s and a 45/16 in 0.22 s compared to the 43/16. The findings of this study suggest that gear ratio choice has a significant effect on peak power production, though time to peak power output is not significantly affected. Therefore, selecting a higher gear ratio results in riders attaining higher power outputs without reducing their start time.

  7. Efficient Second Harmonic Conversion of Broadband High-Peak-Power Nd:Glass Laser Radiation Using Large-Aperture KDP Crystals in Quadrature

    DTIC Science & Technology

    1989-06-23

    pp. 3633-3643, October 1982. 16. W. Seka, S. D. Jacobs, J. E. Rizzo , R. Boni, and R. S. Craxton, ’Demonstration of High Efficiency Third Harmonic...2156-2170, November 1980. 26. N. Bloembergen, Nonlinear Optics. New York: Benjamin , 1965. 27. J. F. Reintjes, Naval Research Laboratory, private comm

  8. Sildenafil does not improve steady state cardiovascular hemodynamics, peak power, or 15-km time trial cycling performance at simulated moderate or high altitudes in men and women.

    PubMed

    Kressler, Jochen; Stoutenberg, Mark; Roos, Bernard A; Friedlander, Anne L; Perry, Arlette C; Signorile, Joseph F; Jacobs, Kevin A

    2011-12-01

    Sildenafil improves oxygen delivery and maximal exercise capacity at very high altitudes (≥ 4,350 m), but it is unknown whether sildenafil improves these variables and longer-duration exercise performance at moderate and high altitudes where competitions are more common. The purpose of this study was to determine the effects of sildenafil on cardiovascular hemodynamics, arterial oxygen saturation (SaO(2)), peak exercise capacity (W (peak)), and 15-km time trial performance in endurance-trained subjects at simulated moderate (MA; ~2,100 m, 16.2% F(I)O(2)) and high (HA; ~3,900 m, 12.8% F(I)O(2)) altitudes. Eleven men and ten women completed two HA W (peak) trials after ingesting placebo or 50 mg sildenafil. Subjects then completed four exercise trials (30 min at 55% of altitude-specific W (peak) + 15-km time trial) at MA and HA after ingesting placebo or 50 mg sildenafil. All trials were performed in randomized, counterbalanced, and double-blind fashion. Sildenafil had little influence on cardiovascular hemodynamics at MA or HA, but did result in higher SaO(2) values (+3%, p < 0.05) compared to placebo during steady state and time trial exercise at HA. W (peak) at HA was 19% lower than SL (p < 0.001) and was not significantly affected by sildenafil. Similarly, the significantly slower time trial performance at MA (28.1 ± 0.5 min, p = 0.016) and HA (30.3 ± 0.6 min, p < 0.001) compared to SL (27.5 ± 0.6 min) was unaffected by sildenafil. We conclude that sildenafil is unlikely to exert beneficial effects at altitudes <4,000 m for a majority of the population.

  9. High Peak Power Microwaves: A Health Hazard

    DTIC Science & Technology

    1993-12-01

    Pyridostigmine substitutes may be equally effective as nerve agent vaccines with fewer side effects . These include Neostigmine , (marketed as Prostigmin...physostlamlne, and similar antlchollnester~ses Including neostigmIne Wa the methylsutfate) and5 ~pyridoetig mine, here Is the Information that you requested

  10. Harmonic generation at high peak power

    SciTech Connect

    Summers, M.A.; Williams, J.D.; Johnson, B.C.; Eimerl, D.

    1985-12-13

    This report reviews progress made in recent years in frequency conversion of laser radiation. By using a material such as potassium dihydrogen phosphate (KDP), intense, coherent light is made available at wavelengths unavailable from the source laser medium. Tests were performed on an array of KDP crystals at the Nova Facility. The tests revealed unexpected losses due to various non-linear effects. (JDH)

  11. Peak-power-point monitor for solar panel

    NASA Technical Reports Server (NTRS)

    Schloss, A. I.

    1972-01-01

    Attempt was made to determine solar cell panel peak power capability without disrupting power flow from panel. Separate solar cell strings were switched from panel circuits, and increasingly larger loads were added rapidly until peak power points were transversed. String wattage output was recorded and all stored string measurements summed together indicate peak power point in panel.

  12. Optimized versus corrected peak power during friction-braked cycle ergometry in males and females.

    PubMed

    James, David V B; Wood, Dan M; Maberly, Tom C B; De Ste Croix, Mark

    2007-06-01

    The aim of this study was to compare optimization and correction procedures for the determination of peak power output during friction-loaded cycle ergometry. Ten male and 10 female sports students each performed five 10-s sprints from a stationary start on a Monark 864 basket-loaded ergometer. Resistive loads of 5.0, 6.5, 8.0, 9.5, and 11.0% body weight were administered in a counterbalanced order, with a recovery period of 10 min between sprints. Peak power was greater and occurred earlier, with less work having been done before the attainment of peak power, when the data were corrected to account for the inertial and frictional characteristics of the ergometer. Corrected peak power was independent of resistive load (P > 0.05), whereas uncorrected peak power varied as a quadratic function of load (P < 0.001). For males and females, optimized peak power (971 +/- 122 and 668 +/- 37 W) was lower (P < 0.01) than either the highest (1074 +/- 111 and 754 +/- 56 W respectively) or the mean (1007 +/- 125 and 701 +/- 45 W respectively) of the five values for corrected peak power. Optimized and mean corrected peak power were highly correlated both in males (r = 0.97, P < 0.001) and females (r = 0.96, P < 0.001). The difference between optimized and mean corrected peak power was 37 +/- 30 W in males and 33 +/- 14 W in females, of which approximately 15 W was due to the correction for frictional losses. We conclude that corrected peak power is independent of resistive load in males and females.

  13. Diode-pumped high-peak-power femtosecond Yb+3:(Gd0.1Y0.9)2SiO5 laser at 1058.5 nm

    NASA Astrophysics Data System (ADS)

    Wang, Yandang; Yang, Kejian; Zhao, Shengzhi; Li, Tao; Qiao, Wenchao; Su, Xiancui; Zhang, Baitao; He, Jingliang; Zheng, Lihe; Su, Liangbi; Xu, Jun; Gao, Zijing

    2017-09-01

    A diode-pumped continuous-wave mode-locked (CWML) femtosecond Yb+3:(Gd0.1Y0.9)2SiO5 (Yb:GYSO) laser at 1058.5 nm with a semiconductor saturable absorber mirror (SESAM) was successfully realized and demonstrated. Pulses with a duration of 186 fs were obtained at a pulse repetition rate of 80.1 MHz with a maximum average output power of 564 mW, corresponding to a maximum single pulse energy of 7.04 nJ and peak power of 37.9 kW. To the best of our knowledge, this is the highest peak power ever obtained from a mode-locked femtosecond Yb:GYSO laser.

  14. onHigh-peak-power strain-compensated GaInAs/AlInAs quantum cascade lasers (λ ˜4.6 μm) based on a slightly diagonal active region design

    NASA Astrophysics Data System (ADS)

    Yang, Q.; Lösch, R.; Bronner, W.; Hugger, S.; Fuchs, F.; Aidam, R.; Wagner, J.

    2008-12-01

    Employing a "slightly diagonal" active region design for the quantum cascade lasers compared to a reference sample based on the conventional vertical transition design [R. Köhler et al., Appl. Phys. Lett. 76, 1092 (2000)], we have improved the maximum operation temperature, room-temperature maximum peak power per facet, and room-temperature slope efficiency from 320 K, 200 mW, and 570 mW/A to higher than 360 K, 3.2 W, and 2200 mW/A, respectively, for the device size of 16 μm×3 mm with as-cleaved facets operated in pulsed mode.

  15. A high-peak-power UV picosecond-pulse light source based on a gain-switched 1.55 microm laser diode and its application to time-resolved spectroscopy of blue-violet materials.

    PubMed

    Sato, Aya; Kono, Shunsuke; Saito, Kyosuke; Sato, Ki-ichi; Yokoyama, Hiroyuki

    2010-02-01

    We generated sub-kilowatt peak-power and 6-ps duration 390-nm optical pulses via the fourth harmonic generation of amplified optical output from a gain-switched 1.55-microm laser diode. We obtained a power-conversion-efficiency of 12% from 1.55-microm to 390-nm light, and subsequently applied the ultraviolet pulses to time-resolved spectroscopy of blue-violet luminescent materials, including a Coumarine dye solution and nitride semiconductor materials using single-photon and two-photon excitation schemes.

  16. Aerobic power and peak power of elite America's Cup sailors.

    PubMed

    Neville, Vernon; Pain, Matthew T G; Folland, Jonathan P

    2009-05-01

    Big-boat yacht racing is one of the only able bodied sporting activities where standing arm-cranking ('grinding') is the primary physical activity. However, the physiological capabilities of elite sailors for standing arm-cranking have been largely unreported. The purpose of the study was to assess aerobic parameters, VO(2peak) and onset of blood lactate (OBLA), and anaerobic performance, torque-crank velocity and power-crank velocity relationships and therefore peak power (P (max)) and optimum crank-velocity (omega(opt)), of America's Cup sailors during standing arm-cranking. Thirty-three elite professional sailors performed a step test to exhaustion, and a subset of ten grinders performed maximal 7 s isokinetic sprints at different crank velocities, using a standing arm-crank ergometer. VO(2peak) was 4.7 +/- 0.5 L/min (range 3.6-5.5 L/min) at a power output of 332 +/- 44 W (range 235-425 W). OBLA occurred at a power output of 202 +/- 31 W (61% of W(max)) and VO(2) of 3.3 +/- 0.4 L/min (71% of VO(2peak)). The torque-crank velocity relationship was linear for all participants (r = 0.9 +/- 0.1). P (max) was 1,420 +/- 37 W (range 1,192-1,617 W), and omega(opt) was 125 +/- 6 rpm. These data are among the highest upper-body anaerobic and aerobic power values reported. The unique nature of these athletes, with their high fat-free mass and specific selection and training for standing arm cranking, likely accounts for the high values. The influence of crank velocity on peak power implies that power production during on-board 'grinding' may be optimised through the use of appropriate gear-ratios and the development of efficient gear change mechanisms.

  17. Compact, 17W average power, 100kW peak power, nanosecond fiber laser system

    NASA Astrophysics Data System (ADS)

    Saracco, Matthieu J.; Logan, David; Green, Jared; Balsley, David; Nelson, Mike; Small, Jay; Mettlen, Scott; Lowder, Tyson L.; McComb, Timothy S.; Kutscha, Tim; Burkholder, Gary; Smith, Michael R.; Kliner, Dahv A. V.; Randall, Matthew; Fanning, Geoff; Bell, Jake

    2013-03-01

    We demonstrate a robust, compact, low-cost, pulsed, linearly polarized, 1064 nm, Yb:fiber laser system capable of generating ~100 kW peak power pulses and >17 W average power at repetition rates of 80 - 285 kHz. The system employs a configurable microchip seed laser that provides nanosecond (~1.0 - 1.5 ns) pulse durations. The seed pulses are amplified in an all-fiber, polarization maintaining, large mode area (LMA) fiber amplifier optimized for high peak power operation. The LMA Yb:fiber amplifier enables near diffraction limited beam quality at 100 kW peak power. The seed laser, fiber amplifier, and beam delivery optics are packaged into an air-cooled laser head of 152×330×87 mm3 with pump power provided from a separate air-cooled laser controller. Due to the high peak power, high beam quality, spectral purity, and linearly polarized nature of the output beam, the laser is readily frequency doubled to 532 nm. Average 532 nm powers up to 7 W and peak powers exceeding 40 kW have been demonstrated. Potential for scaling to higher peak and average powers in both the green and infrared (IR) will be discussed. This laser system has been field tested and demonstrated in numerous materials processing applications in both the IR and green, including scribing and marking. We discuss recent results that demonstrate success in processing a diverse array of representative industrial samples.

  18. Peak power prediction of a vanadium redox flow battery

    NASA Astrophysics Data System (ADS)

    Yu, V. K.; Chen, D.

    2014-12-01

    The vanadium redox flow battery (VRFB) is a promising grid-scale energy storage technology, but future widespread commercialization requires a considerable reduction in capital costs. Determining the appropriate battery size for the intended power range can help minimize the amount of materials needed, thereby reducing capital costs. A physics-based model is an essential tool for predicting the power range of large scale VRFB systems to aid in the design optimization process. This paper presents a modeling framework that accounts for the effects of flow rate on the pumping losses, local mass transfer rate, and nonuniform vanadium concentration in the cell. The resulting low-order model captures battery performance accurately even at high power densities and remains computationally practical for stack-level optimization and control purposes. We first use the model to devise an optimal control strategy that maximizes battery life during discharge. Assuming optimal control is implemented, we then determine the upper efficiency limits of a given VRFB system and compare the net power and associated overpotential and pumping losses at different operating points. We also investigate the effects of varying the electrode porosity, stack temperature, and total vanadium concentration on the peak power.

  19. RF peak power reduction in CAIPIRINHA excitation by interslice phase optimization.

    PubMed

    Sbrizzi, Alessandro; Poser, Benedikt A; Tse, Desmond H Y; Hoogduin, Hans; Luijten, Peter R; van den Berg, Cornelis A T

    2015-11-01

    The purpose of this work was to show that the overall peak power of RF pulses for CAIPIRINHA excitation can be substantially reduced by applying interslice phase relaxation. The optimal phases are scan dependent and can be quickly calculated by the proposed method. The multi-band RF pulse design is implemented as the minimization of a linear objective function with quadratic constraints. The interslice phase is considered to be a variable for optimization. In the case of a phase cycling scheme (CAIPIRINHA), the peak power is considered over all pulses. The computation time (about 1 s) is compatible with online RF pulse design. It is shown that the optimal interslice phases depend on the CAIPIRINHA scheme used and that RF peak power is reduced when the CAIPIRINHA phase cycling is taken into account in the optimization. The proposed method is extremely fast and results in RF pulses with low peak power for CAIPIRINHA excitation. The MATLAB implementation is given in the appendix; it allows for online determination of scan-dependent phase parameters. Furthermore, the method can be easily extended to pTx shimming systems in the context of multi-slice excitations, and this possibility is included in the software.

  20. Stack and dump: Peak-power scaling by coherent pulse addition in passive cavities

    NASA Astrophysics Data System (ADS)

    Breitkopf, S.; Eidam, T.; Klenke, A.; Carstens, H.; Holzberger, S.; Fill, E.; Schreiber, T.; Krausz, F.; Tünnermann, A.; Pupeza, I.; Limpert, J.

    2015-10-01

    During the last decades femtosecond lasers have proven their vast benefit in both scientific and technological tasks. Nevertheless, one laser feature bearing the tremendous potential for high-field applications, delivering extremely high peak and average powers simultaneously, is still not accessible. This is the performance regime several upcoming applications such as laser particle acceleration require, and therefore, challenge laser technology to the fullest. On the one hand, some state-of-the-art canonical bulk amplifier systems provide pulse peak powers in the range of multi-terawatt to petawatt. On the other hand, concepts for advanced solid-state-lasers, specifically thin disk, slab or fiber systems have shown their capability of emitting high average powers in the kilowatt range with a high wall-plug-efficiency while maintaining an excellent spatial and temporal quality of the output beam. In this article, a brief introduction to a concept for a compact laser system capable of simultaneously providing high peak and average powers all along with a high wall-plug efficiency will be given. The concept relies on the stacking of a pulse train emitted from a high-repetitive femtosecond laser system in a passive enhancement cavity, also referred to as temporal coherent combining. In this manner, the repetition rate is decreased in favor of a pulse energy enhancement by the same factor while the average power is almost preserved. The key challenge of this concept is a fast, purely reflective switching element that allows for the dumping of the enhanced pulse out of the cavity. Addressing this challenge could, for the first time, allow for the highly efficient extraction of joule-class pulses at megawatt average power levels and thus lead to a whole new area of applications for ultra-fast laser systems.

  1. High-peak-power single-oscillator actively Q-switched mode-locked Tm3+-doped fiber laser and its application for high-average output power mid-IR supercontinuum generation in a ZBLAN fiber.

    PubMed

    Kneis, Christian; Donelan, Brenda; Manek-Hönninger, Inka; Robin, Thierry; Cadier, Benoît; Eichhorn, Marc; Kieleck, Christelle

    2016-06-01

    A single-oscillator actively Q-switched mode-locked (QML) thulium-doped silica fiber laser is presented and used to pump a ZrF4-BaF2-LaF3-AlF3-NaF (ZBLAN) fiber for mid-infrared (mid-IR) supercontinuum (SC) generation. The fiber laser provided high-peak-power levels directly from the oscillator delivering single mode-locked pulse energies up to 48 μJ, being 2-4 orders of magnitude higher than conventional continuous wave mode-locked lasers. By pumping a ZBLAN fiber specially designed for high-output-power SC generation, 7.8 W have been achieved in all spectral bands with a spectrum extending to 4.2 μm.

  2. Peak power during repeated wingate trials: implications for testing.

    PubMed

    Kohler, Ryan M; Rundell, Kenneth W; Evans, Tina M; Levine, Alan M

    2010-02-01

    Maximal power production is of primary importance for many sporting events. Therefore, using a test that has been shown to be both valid and reliable will allow for accurate baseline testing, measurement of progress, and evaluation of performance. This study examined peak power (PP) during repeated Wingate trials after no warm-up (NWU), a steady state warm-up, and an interval warm-up. In a randomized placebo-controlled study, 11 subjects (38 +/- 8.2 years) performed two 10-second Wingate trials with 4 minutes of recovery between efforts. Warm-up protocols were completed before each Wingate trial and were immediately followed by trial I. Peak power was measured during each trial. Results indicate that PP is not significantly (p > 0.05) different from trial I to trial II for either of the warm-up protocols. The NWU trial II was significantly greater than the NWU trial I (855 +/- 230 W > 814 +/- 222 W, p < 0.05) when analyzed with a paired samples t-test. Peak power appears to be greatest after a general self-selected warm-up, but not after a previously intense bike warm-up. When testing for maximal power output via the Wingate anaerobic test, one should allow for a familiarization trial and should ensure full recovery between this trial and the baseline evaluation.

  3. In vivo two-photon imaging of mouse hippocampal neurons in dentate gyrus using a light source based on a high-peak power gain-switched laser diode.

    PubMed

    Kawakami, Ryosuke; Sawada, Kazuaki; Kusama, Yuta; Fang, Yi-Cheng; Kanazawa, Shinya; Kozawa, Yuichi; Sato, Shunichi; Yokoyama, Hiroyuki; Nemoto, Tomomi

    2015-03-01

    In vivo two-photon microscopy is an advantageous technique for observing the mouse brain at high resolution. In this study, we developed a two-photon microscopy method that uses a 1064-nm gain-switched laser diode-based light source with average power above 4 W, pulse width of 7.5-picosecond, repetition rate of 10-MHz, and a high-sensitivity photomultiplier tube. Using this newly developed two-photon microscope for in vivo imaging, we were able to successfully image hippocampal neurons in the dentate gyrus and obtain panoramic views of CA1 pyramidal neurons and cerebral cortex, regardless of age of the mouse. Fine dendrites in hippocampal CA1 could be imaged with a high peak-signal-to-background ratio that could not be achieved by titanium sapphire laser excitation. Finally, our system achieved multicolor imaging with neurons and blood vessels in the hippocampal region in vivo. These results indicate that our two-photon microscopy system is suitable for investigations of various neural functions, including the morphological changes undergone by neurons during physiological phenomena.

  4. Wingate Anaerobic Test Peak Power and Anaerobic Capacity Classification for Men and Women Intercollegiate Athletes

    DTIC Science & Technology

    2009-12-01

    including football, sprinting, soccer, baseball, lacrosse, and gymnastics - use anaerobic metabolism extensively during competition. This study...1 . 3 62j + 7.7 167.1 + 7 .9 Tennis, track, soccer, and gymnastics urements allow a coach to observe individual improvements; however, it is...require short bursts of peak power and a high anaerobic capacity during competition to include lacrosse, gymnastics , sprint cycling, football, baseball

  5. Megawatt peak power level sub-100 fs Yb:KGW oscillators.

    PubMed

    Zhao, Haitao; Major, Arkady

    2014-12-15

    We report on the first demonstration, to the best of our knowledge, of sub-100 fs pulses directly from the diode-pumped mode-locked Yb:KGW bulk oscillators operated at a low repetition rate. The 36 MHz oscillator delivered 78 fs pulses with pulse energy of 50 nJ and peak power of 0.65 MW. The cavity was extended by inserting a 1:1 imaging telescope, allowing 85 fs pulses to be generated at a repetition rate of 18 MHz. The pulse energy up to 83 nJ was reached, corresponding to a peak power as high as 1 MW. Sub-100 fs regime was achieved by dual action of the Kerr-lens and saturable absorber (KLAS) mode locking.

  6. Narrow linewidth picosecond pulsed laser with mega-watt peak power at UV wavelength

    SciTech Connect

    Liu, Yun; Huang, Chunning; Deibele, Craig Edmond

    2013-01-01

    We demonstrate a master oscillator power amplifier (MOPA) burst mode laser system to generate 66 ps/402.5 MHz pulses with mega-watt peak power at 355 nm. The seed laser is based on a direct electro-optic modulation of a fiber laser output. A very high extinction ratio (45 dB) has been achieved by using an adaptive bias control. The multi-stage Nd:YAG amplifier system allows a uniformly temporal shaping of macropulses with tunable pulse duration. The light output form the amplifier is converted to 355 nm and over 1 MW UV peak power is obtained when the laser is operating in a 5- s/10-Hz macropulse mode. The laser output has a transform limited spectrum bandwidth with a very narrow linewidth of individual laser mode. The immediate application of the laser system is the laser assisted hydrogen ion beam stripping for the Spallation Neutron Source (SNS).

  7. Assessment of peak power and short-term work capacity.

    PubMed

    MacIntosh, Brian R; Rishaug, Peter; Svedahl, Krista

    2003-02-01

    The purpose of this study was to evaluate conditions for conducting a 30 s Wingate test such as load selection, and the method of starting the test (stationary or flying start). Nine male and four female athletes volunteered to be tested on four laboratory visits. Tests were performed on a modified Monark cycle ergometer (Varberg, Sweden) equipped with force transducers on the friction belt and an optical encoder for velocity measurement. Power was calculated with the moment of inertia (I) of the flywheel taken into consideration. One laboratory visit was used to determine individualized optimal resistance conditions. The other three visits were for performance of one of three Wingate tests: a flying start with 0.834 N x kg(-1) [85 g x kg(-1) body weight (BW)] resistance (FLY-0.8); a stationary start with 0.834 N x kg(-1) BW resistance (ST-0.8), or a stationary start with optimal resistance (ST-OPT). FLY-0.8 gave a lower (P<0.05) value for short-term work capacity [19,986 (827) J] than either ST-OPT [23,014 (1,167) J] or ST-0.8 [22,321 (1075) J]. Peak power output per pedal revolution was lower ( P<0.005) for FLY-0.8 [833 (40) W] than for either ST-0.8 [974 (57) W] or ST-OPT [989 (61) W]. The results of this study demonstrate that higher values for peak power and short-term work capacity are obtained with a test from a stationary start. It is apparently not necessary to use an individualized optimal resistance when I is considered in a Wingate test initiated from a standstill.

  8. Optimal loading for the development of peak power output in professional rugby players.

    PubMed

    Bevan, Huw R; Bunce, Paul J; Owen, Nick J; Bennett, Mark A; Cook, Christian J; Cunningham, Dan J; Newton, Robert U; Kilduff, Liam P

    2010-01-01

    The ability to develop high levels of muscular power is considered an essential component of success in many sporting activities; however, the optimal load for the development of peak power during training remains controversial. Our aim in the present study was to determine the optimal load required to observe peak power output during the ballistic bench throw (BBT) and squat jump (SJ) in professional rugby players. Forty-seven, professional, male, rugby players of (mean +/- SD) mass 101.3 +/- 12.8 kg and height 1.82 +/- 0.08 m volunteered and gave informed consent for this study, which was approved by a university ethics committee. Players performed BBT at loads of 20, 30, 40, 50, and 60% of their predetermined 1 repetition maximum (1RM) and SJ at loads of 0, (body mass only), 20, 30, 40, 50, and 60% of their predetermined 1RM in a randomized and balanced order. Power output (PO) was determined by measurement of barbell displacement with subsequent calculation of velocity, force, and power. Relative load had a significant effect on PO for both the BBT (effect size eta(2): 0.297, p < 0.001) and SJ (Effect Size eta(2): 0.709, p < 0.001). Peak power output was produced when the athletes worked against an external load equal to 30% 1RM for the upper body and 0% 1RM for the lower body.

  9. Pump enhanced monochromatic terahertz-wave parametric oscillator toward megawatt peak power.

    PubMed

    Saito, Kyosuke; Tanabe, Tadao; Oyama, Yutaka

    2014-10-01

    Pump enhanced optical parametric oscillation under a cavity phase matching configuration is an effective way to obtain monochromatic THz waves with high pulse energy. Numerical simulations are conducted for THz wave generations using a GaP sheet cavity. By optimizing the optical pulse duration and cavity configuration, the estimated peak power of THz waves is 4 MW at 3 THz, which corresponds to the photon conversion efficiency of η≈0.81. Our proposed scheme can generate a THz wave with high pulse energy, which is suitable for the nonlinear optical effects in the THz frequency region.

  10. Development and Production of a 201 MHz, 5.0 MW Peak Power Klystron

    SciTech Connect

    Aymar, Galen; Eisen, Edward; Stockwell, Brad; Begum, rasheda; Lenci, Steve; Eisner, Rick; Cesca, Eugene

    2016-01-01

    Communications & Power Industries LLC has designed and manufactured the VKP-8201A, a high peak power, high gain, VHF band klystron. The klystron operates at 201.25 MHz, with 5.0 MW peak output power, 34 kW average output power, and a gain of 36 dB. The klystron is designed to operate between 1.0 MW and 4.5 MW in the linear range of the transfer curve. The klystron utilizes a unique magnetic field which enables the use of a proven electron gun design with a larger electron beam requirement. Experimental and predicted performance data are compared.

  11. Peak power of muscles injured by lengthening contractions.

    PubMed

    Widrick, Jeffrey J; Barker, Tyler

    2006-10-01

    Excessive or extreme lengthening contractions have a well-characterized depressive effect on skeletal muscle isometric force. In addition to producing force, active muscles must often shorten in order to meet the power requirements of locomotion and other physical activities. However, the impact of lengthening contractions on muscle power is poorly understood. We evaluated the effect of 20 isometric contractions or 20 lengthening contractions (20% strain at 1.5 fiber lengths/s) on the force-velocity-power relationships of mouse soleus muscles in vitro at 35 degrees C. Pre- and posttreatment data were obtained as the muscles shortened through their optimal length (Lo). The isometric treatment did not alter Lo, the curvature of the force-velocity relationship (a/Po), or soleus maximal shortening velocity (Vmax), whereas peak force (Po) displayed a slow, time-dependent decline of 10% across the experiments. Following the lengthening treatment, Lo increased by 6%, a/Po increased by 22%, and Vmax and Po fell by 24% and 26%, respectively. Under optimal conditions for producing power, muscles damaged by lengthening contractions attained 22% less force and shortened 20% more slowly than before damage. Consequently, soleus peak power fell 37% after lengthening, a 2.5-fold greater decline than noted for the isometric treatment. Under the conditions studied here, the excessive power loss following lengthening contractions was due to force and velocity deficits of approximately equal relative magnitude. Because power represents the ability of the muscle to perform work, reductions in both force and shortening velocity should be considered when evaluating and treating lengthening-induced skeletal muscle injuries.

  12. Narrow linewidth picosecond UV pulsed laser with mega-watt peak power.

    PubMed

    Huang, Chunning; Deibele, Craig; Liu, Yun

    2013-04-08

    We demonstrate a master oscillator power amplifier (MOPA) burst mode laser system that generates 66 ps/402.5 MHz pulses with mega-watt peak power at 355 nm. The seed laser consists of a single frequency fiber laser (linewidth < 5 KHz), a high bandwidth electro-optic modulator (EOM), a picosecond pulse generator, and a fiber based preamplifier. A very high extinction ratio (45 dB) has been achieved by using an adaptive bias control of the EOM. The multi-stage Nd:YAG amplifier system allows a uniformly temporal shaping of the macropulse with a tunable pulse duration. The light output from the amplifier is converted to 355 nm, and over 1 MW peak power is obtained when the laser is operating in a 5-μs/10-Hz macropulse mode. The laser output has a transform-limited spectrum with a very narrow linewidth of individual longitudinal modes. The immediate application of the laser system is the laser-assisted hydrogen ion beam stripping for the Spallation Neutron Source (SNS).

  13. Method and device for remotely monitoring an area using a low peak power optical pump

    DOEpatents

    Woodruff, Steven D.; Mcintyre, Dustin L.; Jain, Jinesh C.

    2014-07-22

    A method and device for remotely monitoring an area using a low peak power optical pump comprising one or more pumping sources, one or more lasers; and an optical response analyzer. Each pumping source creates a pumping energy. The lasers each comprise a high reflectivity mirror, a laser media, an output coupler, and an output lens. Each laser media is made of a material that emits a lasing power when exposed to pumping energy. Each laser media is optically connected to and positioned between a corresponding high reflectivity mirror and output coupler along a pumping axis. Each output coupler is optically connected to a corresponding output lens along the pumping axis. The high reflectivity mirror of each laser is optically connected to an optical pumping source from the one or more optical pumping sources via an optical connection comprising one or more first optical fibers.

  14. Lightweight Battery Charge Regulator Used to Track Solar Array Peak Power

    NASA Technical Reports Server (NTRS)

    Soeder, James F.; Button, Robert M.

    1999-01-01

    A battery charge regulator based on the series-connected boost regulator (SCBR) technology has been developed for high-voltage spacecraft applications. The SCBR regulates the solar array power during insolation to prevent battery overcharge or undercharge conditions. It can also be used to provide regulated battery output voltage to spacecraft loads if necessary. This technology uses industry-standard dc-dc converters and a unique interconnection to provide size, weight, efficiency, fault tolerance, and modularity benefits over existing systems. The high-voltage SCBR shown in the photograph has demonstrated power densities of over 1000 watts per kilogram (W/kg). Using four 150-W dc-dc converter modules, it can process 2500 W of power at 120 Vdc with a minimum input voltage of 90 Vdc. Efficiency of the SCBR was 94 to 98 percent over the entire operational range. Internally, the unit is made of two separate SCBR s, each with its own analog control circuitry, to demonstrate the modularity of the technology. The analog controllers regulate the output current and incorporate the output voltage limit with active current sharing between the two units. They also include voltage and current telemetry, on/off control, and baseplate temperature sensors. For peak power tracking, the SCBR was connected to a LabView-based data acquisition system for telemetry and control. A digital control algorithm for tracking the peak power point of a solar array was developed using the principle of matching the source impedance with the load impedance for maximum energy transfer. The algorithm was successfully demonstrated in a simulated spacecraft electrical system at the Boeing PhantomWorks High Voltage Test Facility in Seattle, Washington. The system consists of a 42-string, high-voltage solar array simulator, a 77-cell, 80-ampere-hour (A-hr) nickel-hydrogen battery, and a constant power-load module. The SCBR and the LabView control algorithm successfully tracked the solar array peak

  15. Lightweight Battery Charge Regulator Used to Track Solar Array Peak Power

    NASA Technical Reports Server (NTRS)

    Soeder, James F.; Button, Robert M.

    1999-01-01

    A battery charge regulator based on the series-connected boost regulator (SCBR) technology has been developed for high-voltage spacecraft applications. The SCBR regulates the solar array power during insolation to prevent battery overcharge or undercharge conditions. It can also be used to provide regulated battery output voltage to spacecraft loads if necessary. This technology uses industry-standard dc-dc converters and a unique interconnection to provide size, weight, efficiency, fault tolerance, and modularity benefits over existing systems. The high-voltage SCBR shown in the photograph has demonstrated power densities of over 1000 watts per kilogram (W/kg). Using four 150-W dc-dc converter modules, it can process 2500 W of power at 120 Vdc with a minimum input voltage of 90 Vdc. Efficiency of the SCBR was 94 to 98 percent over the entire operational range. Internally, the unit is made of two separate SCBR s, each with its own analog control circuitry, to demonstrate the modularity of the technology. The analog controllers regulate the output current and incorporate the output voltage limit with active current sharing between the two units. They also include voltage and current telemetry, on/off control, and baseplate temperature sensors. For peak power tracking, the SCBR was connected to a LabView-based data acquisition system for telemetry and control. A digital control algorithm for tracking the peak power point of a solar array was developed using the principle of matching the source impedance with the load impedance for maximum energy transfer. The algorithm was successfully demonstrated in a simulated spacecraft electrical system at the Boeing PhantomWorks High Voltage Test Facility in Seattle, Washington. The system consists of a 42-string, high-voltage solar array simulator, a 77-cell, 80-ampere-hour (A-hr) nickel-hydrogen battery, and a constant power-load module. The SCBR and the LabView control algorithm successfully tracked the solar array peak

  16. Optimal loading range for the development of peak power output in the hexagonal barbell jump squat.

    PubMed

    Turner, Thomas S; Tobin, Daniel P; Delahunt, Eamonn

    2015-06-01

    Recent studies indicate that the utilization of the hexagonal barbell jump squat (HBJS) compared with the traditional barbell jump squat may offer a superior method of developing peak power. The notion that a single optimal load may be prescribed in training programs aiming to develop peak power is subject to debate. The purpose of this study was to identify the optimal load corresponding with peak power output during the HBJS in professional rugby union players. Seventeen professional rugby union players participated in this study. Participants performed 3 unloaded countermovement jumps on a force plate and 3 HBJS at each of the following randomized loads: 10, 20, 30, and 40% of box squat 1 repetition maximum (1RM). Peak power output was the dependent variable of interest. A one-way repeated measures analysis of variance was conducted to compare peak power output across each load. Peak power output was the dependent variable of interest. A significant main effect for load was observed (Wilk's Lambda = 0.11, F(4,13) = 18.07, p < 0.01, partial η2 = 0.88). Results of the Bonferroni-adjusted pairwise comparisons indicated that peak power output in the HBJS is optimized at a load range between 10 and 20% of box squat 1RM. The results of this study indicate that the use of the HBJS with a training load between 10 and 20% of box squat 1RM optimizes peak power output in professional rugby union players.

  17. Peak power reduction and energy efficiency improvement with the superconducting flywheel energy storage in electric railway system

    NASA Astrophysics Data System (ADS)

    Lee, Hansang; Jung, Seungmin; Cho, Yoonsung; Yoon, Donghee; Jang, Gilsoo

    2013-11-01

    This paper proposes an application of the 100 kWh superconducting flywheel energy storage systems to reduce the peak power of the electric railway system. The electric railway systems have high-power characteristics and large amount of regenerative energy during vehicles’ braking. The high-power characteristic makes operating cost high as the system should guarantee the secure capacity of electrical equipment and the low utilization rate of regenerative energy limits the significant energy efficiency improvement. In this paper, it had been proved that the peak power reduction and energy efficiency improvement can be achieved by using 100 kWh superconducting flywheel energy storage systems with the optimally controlled charging or discharging operations. Also, economic benefits had been assessed.

  18. 1.38 MW peak power dual-loss modulated sub-nanosecond green laser with EO and graphene

    NASA Astrophysics Data System (ADS)

    Tang, Wenjing; Zhao, Jia; Yang, Kejian; Zhao, Shengzhi; Li, Guiqiu; Li, Dechun; Li, Tao; Qiao, Wenchao

    2016-12-01

    By simultaneously employing electro-optic (EO) modulator and Graphene saturable absorber (SA) in a dual-loss-modulated Q-switched and mode-locking (QML) Nd:Lu0.15Y0.85VO4/KTP green laser, the sub-nanosecond single mode-locking green laser is demonstrated with high peak power, low repetition rate and high stability. The monolayer and 3-layer graphene sheets grown by chemical vapor deposition (CVD) method were used as SAs in the experiment. When the pump power reached 10.72 W, the maximum peak power obtained from the doubly QML laser with EO and monolayer graphene-SA was 1.38 MW, corresponding to a pulse duration of 480 ps. The shortest pulse width of 340 ps was obtained with a 3-layer graphene-SA.

  19. Energy and peak power saved by passively cooled residences

    NASA Astrophysics Data System (ADS)

    Clark, G.; Loxsom, F.; Doderer, E.; Vieira, R.; Fleischhacker, P.

    1983-11-01

    The energy displacement potential of roof pond cooling in humid climates is sensitive to the type of dehumidification equipment employed and the humidity levels allowed. The simulated energy requirements of roof pond residences assisted by two high efficiency dehumidifier options are described. One dehumidifier was a vapor compression air conditioner with sensible cooling recovery by an air-to-air heat exchanger (improved mechanical dehumidification or IMD). The second option was a solar regenerated desiccant dehumidifier (SRDD). An IMD assisted roof pond house had energy savings of 30 to 65% in humid climates compared to the conventional house; an SRDD assisted roof pond house had energy savings of 70 to 75% in humid climates.

  20. Variability in Laboratory vs. Field Testing of Peak Power, Torque, and Time of Peak Power Production Among Elite Bicycle Motocross Cyclists.

    PubMed

    Rylands, Lee P; Roberts, Simon J; Hurst, Howard T

    2015-09-01

    The aim of this study was to ascertain the variation in elite male bicycle motocross (BMX) cyclists' peak power, torque, and time of power production during laboratory and field-based testing. Eight elite male BMX riders volunteered for the study, and each rider completed 3 maximal sprints using both a Schoberer Rad Messtechnik (SRM) ergometer in the laboratory and a portable SRM power meter on an Olympic standard indoor BMX track. The results revealed a significantly higher peak power (p ≤ 0.001, 34 ± 9%) and reduced time of power production (p ≤ 0.001, 105 ± 24%) in the field tests when compared with laboratory-derived values. Torque was also reported to be lower in the laboratory tests but not to an accepted level of significance (p = 0.182, 6 ± 8%). These results suggest that field-based testing may be a more effective and accurate measure of a BMX rider's peak power, torque, and time of power production.

  1. Appropriate Loads for Peak-Power During Resisted Sprinting on a Non-Motorized Treadmill

    PubMed Central

    Andre, Matthew J.; Fry, Andrew C.; Lane, Michael T.

    2013-01-01

    The purpose of this study was to determine the load which allows the highest peak power for resisted sprinting on a non-motorized treadmill and to determine if other variables are related to individual differences. Thirty college students were tested for vertical jump, vertical jump peak and mean power, 10 m sprint, 20 m sprint, leg press 1 RM, leg press 1 RM relative to body weight, leg press 1 RM relative to lean body mass, leg press 1 RM power, and leg press power at 80% of 1 RM. Participants performed eight resisted sprints on a non-motorized treadmill, with increasing relative loads expressed as percent of body weight. Sprint peak power was measured for each load. Pearson correlations were used to determine if relationships between the sprint peak power load and the other variables were significant. The sprint peak power load had a mode of 35% with 73% of all participants having a relative sprint peak power load between 25–35%. Significant correlations occurred between sprint peak power load and body weight, lean body mass, vertical jump peak and mean power, leg press 1 RM, leg press 1 RM relative to lean body mass, leg press 1 RM power, and leg press power at 80% of 1 RM (r = 0.44, 0.43, 0.39, 0.37, 0.47, 0.39, 0.46, and 0.47, respectively). Larger, stronger, more powerful athletes produced peak power at a higher relative load during resisted sprinting on a non-motorized treadmill. PMID:24233103

  2. Operation of Direct Drive Systems: Experiments in Peak Power Tracking and Multi-Thruster Control

    NASA Technical Reports Server (NTRS)

    Snyder, John Steven; Brophy, John R.

    2013-01-01

    Direct-drive power and propulsion systems have the potential to significantly reduce the mass of high-power solar electric propulsion spacecraft, among other advantages. Recent experimental direct-drive work has significantly mitigated or retired the technical risks associated with single-thruster operation, so attention is now moving toward systems-level areas of interest. One of those areas is the use of a Hall thruster system as a peak power tracker to fully use the available power from a solar array. A simple and elegant control based on the incremental conductance method, enhanced by combining it with the unique properties of Hall thruster systems, is derived here and it is shown to track peak solar array power very well. Another area of interest is multi-thruster operation and control. Dualthruster operation was investigated in a parallel electrical configuration, with both thrusters operating from discharge power provided by a single solar array. Startup and shutdown sequences are discussed, and it is shown that multi-thruster operation and control is as simple as for a single thruster. Some system architectures require operation of multiple cathodes while they are electrically connected together. Four different methods to control the discharge current emitted by individual cathodes in this configuration are investigated, with cathode flow rate control appearing to be advantageous. Dual-parallel thruster operation with equal cathode current sharing at total powers up to 10 kW is presented.

  3. Operation of Direct Drive Systems: Experiments in Peak Power Tracking and Multi-Thruster Control

    NASA Technical Reports Server (NTRS)

    Snyder, John Steven; Brophy, John R.

    2013-01-01

    Direct-drive power and propulsion systems have the potential to significantly reduce the mass of high-power solar electric propulsion spacecraft, among other advantages. Recent experimental direct-drive work has significantly mitigated or retired the technical risks associated with single-thruster operation, so attention is now moving toward systems-level areas of interest. One of those areas is the use of a Hall thruster system as a peak power tracker to fully use the available power from a solar array. A simple and elegant control based on the incremental conductance method, enhanced by combining it with the unique properties of Hall thruster systems, is derived here and it is shown to track peak solar array power very well. Another area of interest is multi-thruster operation and control. Dualthruster operation was investigated in a parallel electrical configuration, with both thrusters operating from discharge power provided by a single solar array. Startup and shutdown sequences are discussed, and it is shown that multi-thruster operation and control is as simple as for a single thruster. Some system architectures require operation of multiple cathodes while they are electrically connected together. Four different methods to control the discharge current emitted by individual cathodes in this configuration are investigated, with cathode flow rate control appearing to be advantageous. Dual-parallel thruster operation with equal cathode current sharing at total powers up to 10 kW is presented.

  4. Aerobic capacity and peak power output of elite quadriplegic games players

    PubMed Central

    Goosey‐Tolfrey, V; Castle, P; Webborn, N

    2006-01-01

    Background Participation in wheelchair sports such as tennis and rugby enables people with quadriplegia to compete both individually and as a team at the highest level. Both sports are dominated by frequent, intermittent, short term power demands superimposed on a background of aerobic activity. Objective To gain physiological profiles of highly trained British quadriplegic athletes, and to examine the relation between aerobic and sprint capacity. Methods Eight male quadriplegic athletes performed an arm crank exercise using an ergometer fitted with a Schoberer Rad Messtechnik (SRM) powermeter. The sprint test consisted of three maximum‐effort sprints of five seconds duration against a resistance of 2%, 3%, and 4% of body mass. The highest power output obtained was recorded (PPO). Peak oxygen consumption (V̇o2peak), peak heart rate (HRpeak), and maximal power output (POaer) were determined. Results Mean POaer was 67.7 (16.2) W, mean V̇o2peak was 0.96 (0.17) litres/min, and HRpeak was 134 (19) beats/min for the group. There was high variability among subjects. Peak power over the five second sprint for the group was 220 (62) W. There was a significant correlation between V̇o2peak (litres/min) and POaer (W) (r  =  0.74, p<0.05). Conclusions These British quadriplegic athletes have relatively high aerobic fitness when compared with the available literature. Moreover, the anaerobic capacity of these athletes appeared to be relatively high compared with paraplegic participants. PMID:16611721

  5. 4.35 kW peak power femtosecond pulse mode-locked VECSEL for supercontinuum generation.

    PubMed

    Wilcox, Keith G; Tropper, Anne C; Beere, Harvey E; Ritchie, David A; Kunert, Bernardette; Heinen, Bernd; Stolz, Wolfgang

    2013-01-28

    We report a passively mode-locked vertical external cavity surface emitting laser (VECSEL) producing 400 fs pulses with 4.35 kW peak power. The average output power was 3.3 W and the VECSEL had a repetition rate of 1.67 GHz at a center wavelength of 1013 nm. A near-antiresonant, substrate-removed, 10 quantum well (QW) gain structure designed to enable femtosecond pulse operation is used. A SESAM which uses fast carrier recombination at the semiconductor surface and the optical Stark effect enables passive mode-locking. When 1 W of the VECSEL output is launched into a 2 m long photonic crystal fiber (PCF) with a 2.2 µm core, a supercontinuum spanning 175 nm, with average power 0.5 W is produced.

  6. Assessment of the limits to peak power of 1100nm broad area single emitter diode lasers under short pulse conditions

    NASA Astrophysics Data System (ADS)

    Wang, X.; Crump, P.; Pietrzak, A.; Schultz, C.; Klehr, A.; Hoffmann, T.; Liero, A.; Ginolas, A.; Einfeldt, S.; Bugge, F.; Erbert, G.; Tränkle, G.

    2009-02-01

    High power diode lasers are the root source of optical energy in all high performance laser systems. As their performance advances, diode lasers are increasingly taking the place of other sources. Short pulse, sub-microsecond-class, high power lasers are important for many applications but historically, diode lasers have not been able to reach high enough peak pulse powers with adequate reliability, limited by physical effects such as facet failure. By combining robust facet passivation with thick super large optical cavity waveguides, greatly increased optical output power can be achieved. We present here the results of a study using commercial high current short pulse sources (>200A, <500ns) to assess the performance and endurance limits of high power broad area devices. We find that our lasers can be driven with a peak power density of over 110MWcm-2 without failure for more than 3×107 pulses. For example, on testing to 240A, single emitter 200μm stripe 1100nm broad area devices reach 124W (46μJ) without failure, and 60μm stripes reach 88W. In practice, high injection effects such as carrier accumulation in waveguide typically limit peak power. We review these remaining limitations, and discuss how they can be overcome.

  7. Coherent Enhancement of 10 s Burst-Mode Ultraviolet Pulses at Megawatt Peak Power

    SciTech Connect

    Abudureyimu, Reheman; Liu, Yun

    2017-01-01

    A doubly-resonant optical cavity and its locking technique have been developed to achieve coherent enhancement of 402.5-MHz, 50-ps, megawatt peak power ultraviolet (355 nm) laser pulses operating at a 10- s/10-Hz burst mode.

  8. An adaptive model for vanadium redox flow battery and its application for online peak power estimation

    NASA Astrophysics Data System (ADS)

    Wei, Zhongbao; Meng, Shujuan; Tseng, King Jet; Lim, Tuti Mariana; Soong, Boon Hee; Skyllas-Kazacos, Maria

    2017-03-01

    An accurate battery model is the prerequisite for reliable state estimate of vanadium redox battery (VRB). As the battery model parameters are time varying with operating condition variation and battery aging, the common methods where model parameters are empirical or prescribed offline lacks accuracy and robustness. To address this issue, this paper proposes to use an online adaptive battery model to reproduce the VRB dynamics accurately. The model parameters are online identified with both the recursive least squares (RLS) and the extended Kalman filter (EKF). Performance comparison shows that the RLS is superior with respect to the modeling accuracy, convergence property, and computational complexity. Based on the online identified battery model, an adaptive peak power estimator which incorporates the constraints of voltage limit, SOC limit and design limit of current is proposed to fully exploit the potential of the VRB. Experiments are conducted on a lab-scale VRB system and the proposed peak power estimator is verified with a specifically designed "two-step verification" method. It is shown that different constraints dominate the allowable peak power at different stages of cycling. The influence of prediction time horizon selection on the peak power is also analyzed.

  9. Peak Power Output Test on a Rowing Ergometer: A Methodological Study.

    PubMed

    Metikos, Boris; Mikulic, Pavle; Sarabon, Nejc; Markovic, Goran

    2015-10-01

    We aimed to examine the reliability and validity of the peak power output test on a rowing ergometer (Concept II Model D Inc.) and to establish the "optimal resistance" at which this peak power output was observed in 87 participants with varying levels of physical activity and rowing expertise: 15 male and 12 female physically inactive students (age: 21 ± 2 years), 16 male and 20 female physically active students (age: 23 ± 2 years), and 15 male and 9 female trained rowers (age: 19 ± 2 years). The participants performed countermovement jump (CMJ) test on a force plate, followed by 3 maximal-effort rowing trials using the lowest, medium, and the highest adjustable resistance settings (i.e., "1", "5," and "10" on the resistance control dial on the ergometer) in randomized order. The test proved to be reliable (coefficients of variation: 2.6-6.5%; intraclass correlation coefficients: 0.87-0.98). The correlation coefficients between CMJ peak power and rowing peak power (both in watts per kilogram) were fairly consistent across all 3 groups of participants and resistance levels, ranging between r = 0.70 and r = 0.78. Finally, the highest power output was observed at the highest resistance setting in 2 nonathletic groups (p < 0.01), whereas rowers seem to produce the highest power output at the moderate-resistance setting. We conclude that the power output test on a Concept II rowing ergometer may serve as a reliable and valid tool for assessing whole-body peak power output in untrained individuals and rowing athletes.

  10. Validity of cycling peak power as measured by a short-sprint test versus the Wingate anaerobic test.

    PubMed

    Coso, Juan Del; Mora-Rodríguez, Ricardo

    2006-06-01

    To validate the measurement of peak power output (PPO) using a short cycling sprint test (inertial load (IL) test), we compare it to the widely accepted Wingate anaerobic test (WAnT). Fifteen healthy, young, active subjects performed 2 experimental trials. In each trial, subjects warmed up and sprinted 4 times for the IL test. After recovery, they cycled for 30 s at maximum capacity for the WAnT. The experimental trial was replicated 3 d later to test for reliability. Inter- and intra-day PPO measured with the IL test was very reliable (R(1) = 0.99 and R(1) = 0.94, respectively). The correlation between the IL and WAnT was highly significant (r = 0.82; P < 0.001), although the absolute PPO values were markedly higher for the IL test (1268 +/- 41 W vs. 786 +/- 27 W; P < 0.001). In conclusion, cycling PPO can be validly assessed with the IL test. The higher PPO attained with an IL test could be related to better identification of peak power, since both velocity and resistance are free to vary during the sprint in comparison with the WAnT, where resistance is fixed. Owing to the short duration of the sprint (4 s) and high intra-day reliability despite a short recovery time (180 s), the IL test is optimal for repeated measurements of anaerobic performance.

  11. Cost-effective retrofit technology for reducing peak power demand in small and medium commercial buildings

    SciTech Connect

    Nutaro, James J.; Fugate, David L.; Kuruganti, Teja; Sanyal, Jibonananda; Starke, Michael R.

    2015-05-27

    We describe a cost-effective retrofit technology that uses collective control of multiple rooftop air conditioning units to reduce the peak power consumption of small and medium commercial buildings. The proposed control uses a model of the building and air conditioning units to select an operating schedule for the air conditioning units that maintains a temperature set point subject to a constraint on the number of units that may operate simultaneously. A prototype of this new control system was built and deployed in a large gymnasium to coordinate four rooftop air conditioning units. Based on data collected while operating this prototype, we estimate that the cost savings achieved by reducing peak power consumption is sufficient to repay the cost of the prototype within a year.

  12. Cost-effective retrofit technology for reducing peak power demand in small and medium commercial buildings

    DOE PAGES

    Nutaro, James J.; Fugate, David L.; Kuruganti, Teja; ...

    2015-05-27

    We describe a cost-effective retrofit technology that uses collective control of multiple rooftop air conditioning units to reduce the peak power consumption of small and medium commercial buildings. The proposed control uses a model of the building and air conditioning units to select an operating schedule for the air conditioning units that maintains a temperature set point subject to a constraint on the number of units that may operate simultaneously. A prototype of this new control system was built and deployed in a large gymnasium to coordinate four rooftop air conditioning units. Based on data collected while operating this prototype,more » we estimate that the cost savings achieved by reducing peak power consumption is sufficient to repay the cost of the prototype within a year.« less

  13. Push-pull converter with energy saving circuit for protecting switching transistors from peak power stress

    NASA Technical Reports Server (NTRS)

    Mclyman, W. T. (Inventor)

    1981-01-01

    In a push-pull converter, switching transistors are protected from peak power stresses by a separate snubber circuit in parallel with each comprising a capacitor and an inductor in series, and a diode in parallel with the inductor. The diode is connected to conduct current of the same polarity as the base-emitter juction of the transistor so that energy stored in the capacitor while the transistor is switched off, to protect it against peak power stress, discharges through the inductor when the transistor is turned on, and after the capacitor is discharges through the diode. To return this energy to the power supply, or to utilize this energy in some external circuit, the inductor may be replaced by a transformer having its secondary winding connected to the power supply or to the external circuit.

  14. Kalman filter for onboard state of charge estimation and peak power capability analysis of lithium-ion batteries

    NASA Astrophysics Data System (ADS)

    Dong, Guangzhong; Wei, Jingwen; Chen, Zonghai

    2016-10-01

    To evaluate the continuous and instantaneous load capability of a battery, this paper describes a joint estimator for state-of-charge (SOC) and state-of-function (SOF) of lithium-ion batteries (LIB) based on Kalman filter (KF). The SOC is a widely used index for remain useful capacity left in a battery. The SOF represents the peak power capability of the battery. It can be determined by real-time SOC estimation and terminal voltage prediction, which can be derived from impedance parameters. However, the open-circuit-voltage (OCV) of LiFePO4 is highly nonlinear with SOC, which leads to the difficulties in SOC estimation. To solve these problems, this paper proposed an onboard SOC estimation method. Firstly, a simplified linearized equivalent-circuit-model is developed to simulate the dynamic characteristics of a battery, where the OCV is regarded as a linearized function of SOC. Then, the system states are estimated based on the KF. Besides, the factors that influence peak power capability are analyzed according to statistical data. Finally, the performance of the proposed methodology is demonstrated by experiments conducted on a LiFePO4 LIBs under different operating currents and temperatures. Experimental results indicate that the proposed approach is suitable for battery onboard SOC and SOF estimation.

  15. Tunable pulse width and multi-megawatt peak-power pulses from a nonlinearly compressed monolithic fiber MOPA system

    NASA Astrophysics Data System (ADS)

    Yamashita, Ryutarou; Maeda, Kazuo; Watanabe, Goro; Tei, Kazuyoku; Yamaguchi, Shigeru; Enokidani, Jun; Sumida, Shin

    2016-03-01

    We report on tunable pulse width and high peak power pulse generation from a nonlinearly compressed monolithic fiber MOPA system. The master seed source employs a Mach-Zehnder intensity modulator (MZIM). This seed source has operational flexibility with respect to pulse width, 90 ps to 2 ns and repetition rate, 200 kHz to 2 MHz. The seed pulses are amplified by a monolithic three-stage amplifier system based on polarization maintain Yb-doped fibers. The maximum output power was 32 W at the shortest pulse condition, the pulse width of 90 ps and the repetition rate of 750 kHz. A spectral width after amplification was broadened to 0.73 nm at RMS width. Both of ASE and SRS are not observed in the spectrum. After amplification, we also demonstrated pulse compression with a small piece of chirped volume Bragg-grating (CVBG) which has the dispersion rate of 81 ps/nm. As a result of pulse compression, the shortest pulse width was reduced from 90 ps to 3.5 ps, which brought an increase of the peak power up to 3.2 MW. The compressed pulses are clean with little structure in their wings. We can expand the operation range of the monolithic fiber MOPA system in pulse width, 3.5 ps to 2 ns.

  16. Attenuated maximal muscle strength and peak power in children with sickle cell disease.

    PubMed

    Dougherty, Kelly A; Schall, Joan I; Rovner, Alisha J; Stallings, Virginia A; Zemel, Babette S

    2011-03-01

    Dominant hand maximal handgrip strength evaluated with a handgrip dynamometer and peak power evaluated with a force plate, adjusted for body size and composition, were compared in African-American children aged 5 to 13 years, with and without type SS sickle cell disease (SCD-SS). Children with SCD-SS (n = 35; age, 9.0 ± 2.0 y) compared with healthy control children (n = 103; age, 8.6 ± 1.8 y) did not differ by age, sex, or pubertal status, yet had significantly lower Z scores for height, weight, body mass index, upper arm muscle area, upper arm fat area, fat mass-for-height and lean mass-for-height. Children with SCD-SS had significantly lower handgrip strength (12.7 ± 3.3 vs. 15.2 ± 5.1 kg, P < 0.008), peak power (882 ± 298 vs. 1167 ± 384 W, P < 0.001), and growth and body composition adjusted Z scores for handgrip strength (0.6 ± 1.3 standard deviations, P < 0.004) and peak power (male children = 1.0 ± 0.8 standard deviations, P < 0.0002; female children = 1.0 ± 1.7 standard deviations, P < 0.006). Maximal muscle strength and peak power are attenuated in children with SCD-SS compared with healthy control children beyond expectation for growth and body composition deficits suggesting that additional factors contribute to attenuation in anaerobic performance.

  17. A peak power tracker for small wind turbines in battery charging applications

    SciTech Connect

    De Broe, A.M.; Drouilhet, S.; Gevorgian, V.

    1999-12-01

    This paper describes the design, implementation and testing of a prototype version of a peak power tracking system for small wind turbines in battery charging applications. The causes for the poor performance of small wind turbines in battery charging applications are explained and previously proposed configurations to increase the power output of the wind turbines are discussed. Through computer modeling of the steady-state operation the potential performance gain of the proposed system in comparison with existing systems is calculated. It is shown that one configuration consisting of reactive compensation by capacitors and a DC/DC converter is able to optimally load the wind turbine and thus obtain maximum energy capture over the whole range of wind speeds. A proof of concept of the peak power tracking system is provided by building and testing a prototype version. The peak power tracking system is tested in combination with a typical small wind turbine generator on a dynamometer. Steady-state operating curves confirming the performance improvement predicted by calculations are presented.

  18. Wingate Anaerobic Test peak power and anaerobic capacity classifications for men and women intercollegiate athletes.

    PubMed

    Zupan, Michael F; Arata, Alan W; Dawson, Letitia H; Wile, Alfred L; Payn, Tamara L; Hannon, Megan E

    2009-12-01

    The Wingate Anaerobic Test (WAnT) has been established as an effective tool in measuring both muscular power and anaerobic capacity in a 30-second time period; however, there are no published normative tables by which to compare WAnT performance in men and women intercollegiate athletics. The purpose of this study was to develop a classification system for anaerobic peak power and anaerobic capacity for men and women National Collegiate Athletic Association (NCAA) Division I college athletes using the WAnT. A total of 1,585 (1,374 men and 211 women) tests were conducted on athletes ranging from the ages of 18 to 25 years using the WAnT. Absolute and relative peak power and anaerobic capacity data were recorded. One-half standard deviations were used to set up a 7-tier classification system (poor to elite) for these assessments. These classifications can be used by athletes, coaches, and practitioners to evaluate anaerobic peak power and anaerobic capacity in their athletes.

  19. Effect of individual time to peak power output on the expression of peak power output in the 30-s Wingate Anaerobic Test.

    PubMed

    Bell, W; Cobner, D M

    2007-02-01

    The objective of the present investigation was to examine a proposal which stated that individual power values should be aligned according to peak power output (PPO) before calculating the mean value of PPO. This procedure removes the variation in time it takes for individuals to reach PPO. Participants were forty-one University Rugby Union Football players of mean age 21.7 +/- 2.6 years, height 181.4 +/- 6.9 cm and body mass 88.9 +/- 12.7 kg. Data were collected using a friction-belt cycle ergometer (Monark 864, Varberg, Sweden). A significantly larger mean value for PPO was found when results were calculated from time-aligned rather than cross-sectional data (1154 +/- 246 vs. 1121 +/- 254 W, p < 0.0001); the mean difference was approximately 3 %. Additionally, the average profile of the power output curve was more reflective of individual power curves. The negative correlation between PPO and the time taken to reach PPO was - 0.32 (p < 0.05), confirming the view that the earlier the time taken to reach PPO the larger the PPO. It was concluded that the mean value of PPO and the corresponding profile for power output curves are best represented by the analysis of time-aligned rather than cross-sectional data.

  20. Diode-pumped gigahertz femtosecond Yb:KGW laser with a peak power of 3.9 kW.

    PubMed

    Pekarek, Selina; Fiebig, Christian; Stumpf, Max Christoph; Oehler, Andreas Ernst Heinz; Paschke, Katrin; Erbert, Götz; Südmeyer, Thomas; Keller, Ursula

    2010-08-02

    We present a diode-pumped Yb:KGW laser with a repetition rate of 1 GHz and a pulse duration of 281 fs at a wavelength of 1041 nm. A high brightness distributed Bragg reflector tapered diode laser is used as a pump source. Stable soliton modelocking is achieved with a semiconductor saturable absorber mirror (SESAM). The obtained average output power is 1.1 W and corresponds to a peak power of 3.9 kW and a pulse energy of 1.1 nJ. With harmonic modelocking we could increase the pulse repetition rate up to 4 GHz with an average power of 900 mW and a pulse duration of 290 fs. This Yb:KGW laser has a high potential for stable frequency comb generation.

  1. Peak power and blade loads on stall-regulated rotors as influenced by different airfoil families

    SciTech Connect

    Tangler, J.L.; Tu, P.K.C.

    1988-08-01

    At the Solar Energy Research Institute (SERI), new airfoils have been developed to help improve the performance and economics of horizontal-axis wind turbines (HAWTS). The objective of this study was to compare the performance characteristics of one of these airfoil families to other commonly used airfoil series for a typical three-bladed, stall-regulated HAWT. The traditional airfoil series chosen for comparison with SERI's new thin airfoil family were the NACA 23XXX, NACA 44XX, and NASA LS(1). The Micon 110 wind turbine was chosen because it is a typical three-bladed, stall-regulated rigid rotor system. The performance characteristics of the different airfoil series were derived analytically using the Eppler airfoil design code in the analysis mode. On a relative basis, this approach to comparing airfoils was considered more accurate than using airfoil performance characteristics based on wind-tunnel test data. After generating the performance characteristics for each airfoil series, the subsequent rotor performance and blade loads were calculated using SERI's PROPSH computer code. Resulting annual energy output, which is dependent on the wind-speed distribution, was calculated using SERI's Systems Engineering and Analysis Computer Code (SEACC). The results of the study show that fixed-wing airfoils generally result in excessive peak power for stall regulated, rigid rotors. By operating the wind turbine at a less desirable blade pitch angle, peak power can be reduced at the expense of higher mean blade loads and lower annual energy output. In contrast, the thin airfoil family was designed to reduce peak power at optimum blade pitch to minimize blade loads and maximize annual energy output. 7 refs., 12 figs.

  2. Estimation of cardiac reserve by peak power: validation and initial application of a simplified index

    NASA Technical Reports Server (NTRS)

    Armstrong, G. P.; Carlier, S. G.; Fukamachi, K.; Thomas, J. D.; Marwick, T. H.

    1999-01-01

    OBJECTIVES: To validate a simplified estimate of peak power (SPP) against true (invasively measured) peak instantaneous power (TPP), to assess the feasibility of measuring SPP during exercise and to correlate this with functional capacity. DESIGN: Development of a simplified method of measurement and observational study. SETTING: Tertiary referral centre for cardiothoracic disease. SUBJECTS: For validation of SPP with TPP, seven normal dogs and four dogs with dilated cardiomyopathy were studied. To assess feasibility and clinical significance in humans, 40 subjects were studied (26 patients; 14 normal controls). METHODS: In the animal validation study, TPP was derived from ascending aortic pressure and flow probe, and from Doppler measurements of flow. SPP, calculated using the different flow measures, was compared with peak instantaneous power under different loading conditions. For the assessment in humans, SPP was measured at rest and during maximum exercise. Peak aortic flow was measured with transthoracic continuous wave Doppler, and systolic and diastolic blood pressures were derived from brachial sphygmomanometry. The difference between exercise and rest simplified peak power (Delta SPP) was compared with maximum oxygen uptake (VO(2)max), measured from expired gas analysis. RESULTS: SPP estimates using peak flow measures correlated well with true peak instantaneous power (r = 0.89 to 0.97), despite marked changes in systemic pressure and flow induced by manipulation of loading conditions. In the human study, VO(2)max correlated with Delta SPP (r = 0.78) better than Delta ejection fraction (r = 0.18) and Delta rate-pressure product (r = 0.59). CONCLUSIONS: The simple product of mean arterial pressure and peak aortic flow (simplified peak power, SPP) correlates with peak instantaneous power over a range of loading conditions in dogs. In humans, it can be estimated during exercise echocardiography, and correlates with maximum oxygen uptake better than ejection

  3. Estimation of cardiac reserve by peak power: validation and initial application of a simplified index

    NASA Technical Reports Server (NTRS)

    Armstrong, G. P.; Carlier, S. G.; Fukamachi, K.; Thomas, J. D.; Marwick, T. H.

    1999-01-01

    OBJECTIVES: To validate a simplified estimate of peak power (SPP) against true (invasively measured) peak instantaneous power (TPP), to assess the feasibility of measuring SPP during exercise and to correlate this with functional capacity. DESIGN: Development of a simplified method of measurement and observational study. SETTING: Tertiary referral centre for cardiothoracic disease. SUBJECTS: For validation of SPP with TPP, seven normal dogs and four dogs with dilated cardiomyopathy were studied. To assess feasibility and clinical significance in humans, 40 subjects were studied (26 patients; 14 normal controls). METHODS: In the animal validation study, TPP was derived from ascending aortic pressure and flow probe, and from Doppler measurements of flow. SPP, calculated using the different flow measures, was compared with peak instantaneous power under different loading conditions. For the assessment in humans, SPP was measured at rest and during maximum exercise. Peak aortic flow was measured with transthoracic continuous wave Doppler, and systolic and diastolic blood pressures were derived from brachial sphygmomanometry. The difference between exercise and rest simplified peak power (Delta SPP) was compared with maximum oxygen uptake (VO(2)max), measured from expired gas analysis. RESULTS: SPP estimates using peak flow measures correlated well with true peak instantaneous power (r = 0.89 to 0.97), despite marked changes in systemic pressure and flow induced by manipulation of loading conditions. In the human study, VO(2)max correlated with Delta SPP (r = 0.78) better than Delta ejection fraction (r = 0.18) and Delta rate-pressure product (r = 0.59). CONCLUSIONS: The simple product of mean arterial pressure and peak aortic flow (simplified peak power, SPP) correlates with peak instantaneous power over a range of loading conditions in dogs. In humans, it can be estimated during exercise echocardiography, and correlates with maximum oxygen uptake better than ejection

  4. Peak power is reduced following lengthening contractions despite a maintenance of shortening velocity.

    PubMed

    Power, Geoffrey A; Dalton, Brian H; Rice, Charles L; Vandervoort, Anthony A

    2013-12-01

    Following repetitive lengthening contractions, power (the product of torque and velocity) is impaired during shortening contractions. However, the relative contribution of each component to power loss and the underlying factors are unclear. We investigated neuromuscular properties of the dorsiflexors in 8 males (27 ± 3 years) and 8 females (26 ± 4 years) for a potential sex-related difference before, during, and after 150 unaccustomed maximal lengthening actions. Velocity-dependent power was determined from shortening contractions at 8 levels (1 N · m to 70% of maximum voluntary isometric contraction (MVC)) before, after, and throughout recovery assessed at 0-30 min, 24 h, and 48 h. Immediately following task termination, both sexes displayed similar impairments of 30%, 4%, and 10% in MVC torque, shortening velocity, and overall peak power, respectively (P < 0.05). Peak rate of isometric torque development (RTD) was reduced by 10% in males, but females exhibited a 35% reduction (P < 0.05). Rate of torque development for the MVC remained depressed in both sexes throughout the 30 min recovery period; however, the RTD returned to normal by 24 h in males but did not recover by 48 h in females. Power was reduced preferentially at higher loads (i.e., 60% MVC), with a greater loss in females (65%) than males (45%). For lower loads (<20% MVC), power was impaired minimally (4%-8%; P < 0.05) and recovered within 30 min in both groups. The reduction in maximal angular velocity persisted until 30 min of recovery, and peak power did not recover until 24 h for both sexes. Unaccustomed lengthening contractions decreased power preferentially at higher loads, whereas peak power was reduced minimally owing to maintenance of maximal shortening velocity.

  5. Thulium-doped fiber chirped-pulse amplification system with 2 GW of peak power.

    PubMed

    Gaida, C; Gebhardt, M; Stutzki, F; Jauregui, C; Limpert, J; Tünnermann, A

    2016-09-01

    Thulium-doped fibers with ultra large mode-field areas offer new opportunities for the power scaling of mid-IR ultrashort-pulse laser sources. Here, we present a laser system delivering a pulse-peak power of 2 GW and a nearly transform-limited pulse duration of 200 fs in combination with 28.7 W of average power. This performance level has been achieved by optimizing the pulse shape, reducing the overlap with atmospheric absorption lines, and incorporating a climate chamber to reduce the humidity of the atmospheric environment.

  6. Design and analysis of a regulated peak-power tracking system

    SciTech Connect

    Huynh, P.T.; Cho, B.H.

    1995-12-31

    Solar cells are known to be nonlinear, and there exists one operating point where the solar array produces maximum power. This nonlinear characteristic has resulted in many different power system configurations that make best use of the solar array. A regulated peak-power tracking (RPPT) system for space power application is proposed. Large-signal stability analysis is provided to understand the main four different modes of operations of the system, as well as the mode transitions. A simple and effective control scheme for the system is also proposed. Small-signal analysis is performed thereafter to provide design optimization, and the predictions are verified by computer simulations.

  7. ATF CO{sub 2} laser system upgrade to terawatt peak power

    SciTech Connect

    Pogorelsky, I.V.

    1995-05-01

    This document describes the proposed upgrade of the 10-GW peak power 50-ps CO{sub 2} laser presently operational at the ATF to the 1 TW level at a shorter, 3--10 ps, pulse duration. The approach adopted is based on state of the art CO{sub 2} laser technology and an experience gained in the course of the ATF laser design and application for the laser accelerator experiment. The proposed upgrade is an economical way for the ATF to become in a short time among leading users facilities available for next generation ({ge} 100 MeV) laser accelerator studies.

  8. MW peak power Er/Yb-doped fiber femtosecond laser amplifier at 1.5 µm center wavelength

    NASA Astrophysics Data System (ADS)

    Han, Seongheum; Jang, Heesuk; Kim, Seungman; Kim, Young-Jin; Kim, Seung-Woo

    2017-08-01

    An erbium (Er)/ytterbium (Yb) co-doped double-clad fiber is configured to amplify single-mode pulses with a high average power of 10 W at a 1.5 µm center wavelength. The pulse duration at the exit of the Er/Yb fiber amplifier is measured to be ~440 fs after grating-based compression. The whole single-mode operation of the amplifier system permits the M 2-value of the output beam quality to be evaluated better than 1.05. By tuning the repetition rate from 100 MHz down to 600 kHz, the pulse peak power is scaled up to 19.1 MW to be the highest ever reported using an Er/Yb single-mode fiber. The proposed amplifier system is well suited for strong-power applications such as free-space LIDAR, non-thermal machining and medical surgery.

  9. Peak power dependence of rovibronic populations below the quasicontinuum during IR multiphoton absorption

    SciTech Connect

    Brenner, D.M.

    1981-02-15

    Rovibronic levels of the ground state of thiophosgene, perturbed by IR multiphoton absorption, are observed under collisionless conditions by laser-induced fluorescence. Evidence is presented that at peak powers of the CO/sub 2/ laser>3 MW/cm/sup 2/ an energy distribution is produced in which the vibrational populations of levels v=0--4,6,8 of the mode ..nu../sub 4/ are depleted or not populated, even though the pumped mode is 2..nu../sub 4/. Only at lower peak powers (longer pulse duration) are population increases observed. Under the latter conditions, it appears that 3..nu../sub 4/ is populated to a smaller extent than (..nu../sub 1/+..nu../sub 3/) to which it is coupled by strong Coriolis interaction. At room temperature no evidence for rotational ''hole burning'' effects during IR pumping are observed in the vibrationless level. The data suggest, in fact, that all rotational levels interact with the laser field, even when thiophosgene is rotationally cooled.

  10. MW peak-power, mJ pulse energy, multi-kHz repetition rate pulses from Yb-doped fiber amplifiers

    NASA Astrophysics Data System (ADS)

    Di Teodoro, Fabio; Brooks, Christopher D.

    2006-02-01

    We report on pulsed fiber-based sources generating high peak and average powers in beams of excellent spectral/spatial quality. In the first setup, a ~10-kHz pulse repetition rate (PRR), 1ns-pulse, Q-switched microlaser seeded a dual-stage amplifier featuring a 40-μm-core Yb-doped photonic-crystal fiber (PCF) as the power amplifier. From this amplifier, we obtained diffraction-limited (M2 = 1.05), ~1ns pulses of 1.1mJ energy, ~1.1MW peak power, ~10.2W average-power, spectral linewidth ~9GHz, negligible nonlinearities, and slope efficiency >73%. In the second setup, we replaced the seed source with a shorter-pulse (<500ps) microchip laser of PRR ~13.4 kHz and obtained diffraction-limited (M2=1.05), ~450ps pulses of energy >0.7mJ, peak power in excess of 1.5 MW, average power ~9.5W, spectral linewidth <35 GHz. To show further power scaling, these pulses were amplified in a 140-μmcore Yb-doped fiber, which yielded multimode (M2 ~ 9), 2.2mJ-energy, 30-W average-power pulses of peak power in excess of 4.5MW, the highest ever obtained in a fiber source, to our knowledge. In the third setup, an Yb-doped, 70μmcore, intrinsically single-mode photonic-crystal rod was used to generate diffraction-limited (M2 ~ 1.1), ~10kHz PRR, ~1ns pulses of 2.05mJ energy, >2 MW peak-power (the highest ever reported in a diffraction-limited fiber source), ~20W average-power, ~13 GHz spectral linewidth, and spectral signal-to-noise ratio >50 dB. Finally, a single polarization large-core Yb-doped PCF was used to demonstrate high-peak-power harmonic generation. We obtained ~1ns pulses of peak powers >410 kW in the green (531nm) and >190kW in the UV (265.5 nm).

  11. Ice Thermal Storage Systems for LWR Supplemental Cooling and Peak Power Shifting

    SciTech Connect

    Haihua Zhao; Hongbin Zhang; Phil Sharpe; Blaise Hamanaka; Wei Yan; WoonSeong Jeong

    2010-06-01

    benefits and avoid forced derating and shutdown during extremely hot weather. For the new plants using dry cooling towers, adding the ice thermal storage systems can effectively reduce the efficiency loss and water consumption during hot weather so that new LWRs could be considered in regions without enough cooling water. \\ This paper presents the feasibility study of using ice thermal storage systems for LWR supplemental cooling and peak power shifting. LWR cooling issues and ITS application status will be reviewed. Two ITS application case studies will be presented and compared with alternative options: one for once-through cooling without enough cooling for short time, and the other with dry cooling. Because capital cost, especially the ice storage structure/building cost, is the major cost for ITS, two different cost estimation models are developed: one based on scaling method, and the other based on a preliminary design using Building Information Modeling (BIM), an emerging technology in Architecture/Engineering/Construction, which enables design options, performance analysis and cost estimating in the early design stage.

  12. Superconducting High Resolution Fast-Neutron Spectrometers

    SciTech Connect

    Hau, Ionel Dragos

    2006-01-01

    Superconducting high resolution fast-neutron calorimetric spectrometers based on 6LiF and TiB{sub 2} absorbers have been developed. These novel cryogenic spectrometers measure the temperature rise produced in exothermal (n, α) reactions with fast neutrons in 6Li and 10B-loaded materials with heat capacity C operating at temperatures T close to 0.1 K. Temperature variations on the order of 0.5 mK are measured with a Mo/Cu thin film multilayer operated in the transition region between its superconducting and its normal state. The advantage of calorimetry for high resolution spectroscopy is due to the small phonon excitation energies kBT on the order of μeV that serve as signal carriers, resulting in an energy resolution ΔE ~ (kBT2C)1/2, which can be well below 10 keV. An energy resolution of 5.5 keV has been obtained with a Mo/Cu superconducting sensor and a TiB2 absorber using thermal neutrons from a 252Cf neutron source. This resolution is sufficient to observe the effect of recoil nuclei broadening in neutron spectra, which has been related to the lifetime of the first excited state in 7Li. Fast-neutron spectra obtained with a 6Li-enriched LiF absorber show an energy resolution of 16 keV FWHM, and a response in agreement with the 6Li(n, α)3H reaction cross section and Monte Carlo simulations for energies up to several MeV. The energy resolution of order of a few keV makes this novel instrument applicable to fast-neutron transmission spectroscopy based on the unique elemental signature provided by the neutron absorption and scattering resonances. The optimization of the energy resolution based on analytical and numerical models of the detector response is discussed in the context of these applications.

  13. High pressure FAST of nanocrystalline barium titanate

    SciTech Connect

    Fraga, Martin B.; Delplanque, Jean -Pierre; Yang, Nancy; Lavernia, Enrique J.; Monson, Todd C.

    2016-06-01

    Here, this work studies the microstructural evolution of nanocrystalline (<1 µm) barium titanate (BaTiO3), and presents high pressure in field-assisted sintering (FAST) as a robust methodology to obtain >100 nm BaTiO3 compacts. Using FAST, two commercial ~50 nm powders were consolidated into compacts of varying densities and grain sizes. Microstructural inhomogeneities were investigated for each case, and an interpretation is developed using a modified Monte Carlo Potts (MCP) simulation. Two recurrent microstructural inhomogeneities are highlighted, heterogeneous grain growth and low-density regions, both ubiqutously present in all samples to varying degrees. In the worst cases, HGG presents an area coverage of 52%. Because HGG is sporadic but homogenous throughout a sample, the catalyst (e.g., the local segregation of species) must be, correspondingly, distributed in a homogenous manner. MCP demonstrates that in such a case, a large distance between nucleating abnormal grains is required—otherwise abnormal grains prematurely impinge on each other, and their size is not distinguishable from that of normal grains. Compacts sintered with a pressure of 300 MPa and temperatures of 900 °C, were 99.5% dense and had a grain size of 90±24 nm. These are unprecedented results for commercial BaTiO3 powders or any starting powder of 50 nm particle size—other authors have used 16 nm lab-produced powder to obtain similar results.

  14. High pressure FAST of nanocrystalline barium titanate

    DOE PAGES

    Fraga, Martin B.; Delplanque, Jean -Pierre; Yang, Nancy; ...

    2016-06-01

    Here, this work studies the microstructural evolution of nanocrystalline (<1 µm) barium titanate (BaTiO3), and presents high pressure in field-assisted sintering (FAST) as a robust methodology to obtain >100 nm BaTiO3 compacts. Using FAST, two commercial ~50 nm powders were consolidated into compacts of varying densities and grain sizes. Microstructural inhomogeneities were investigated for each case, and an interpretation is developed using a modified Monte Carlo Potts (MCP) simulation. Two recurrent microstructural inhomogeneities are highlighted, heterogeneous grain growth and low-density regions, both ubiqutously present in all samples to varying degrees. In the worst cases, HGG presents an area coverage ofmore » 52%. Because HGG is sporadic but homogenous throughout a sample, the catalyst (e.g., the local segregation of species) must be, correspondingly, distributed in a homogenous manner. MCP demonstrates that in such a case, a large distance between nucleating abnormal grains is required—otherwise abnormal grains prematurely impinge on each other, and their size is not distinguishable from that of normal grains. Compacts sintered with a pressure of 300 MPa and temperatures of 900 °C, were 99.5% dense and had a grain size of 90±24 nm. These are unprecedented results for commercial BaTiO3 powders or any starting powder of 50 nm particle size—other authors have used 16 nm lab-produced powder to obtain similar results.« less

  15. High pressure FAST of nanocrystalline barium titanate

    SciTech Connect

    Fraga, Martin B.; Delplanque, Jean -Pierre; Yang, Nancy; Lavernia, Enrique J.; Monson, Todd C.

    2016-06-01

    Here, this work studies the microstructural evolution of nanocrystalline (<1 µm) barium titanate (BaTiO3), and presents high pressure in field-assisted sintering (FAST) as a robust methodology to obtain >100 nm BaTiO3 compacts. Using FAST, two commercial ~50 nm powders were consolidated into compacts of varying densities and grain sizes. Microstructural inhomogeneities were investigated for each case, and an interpretation is developed using a modified Monte Carlo Potts (MCP) simulation. Two recurrent microstructural inhomogeneities are highlighted, heterogeneous grain growth and low-density regions, both ubiqutously present in all samples to varying degrees. In the worst cases, HGG presents an area coverage of 52%. Because HGG is sporadic but homogenous throughout a sample, the catalyst (e.g., the local segregation of species) must be, correspondingly, distributed in a homogenous manner. MCP demonstrates that in such a case, a large distance between nucleating abnormal grains is required—otherwise abnormal grains prematurely impinge on each other, and their size is not distinguishable from that of normal grains. Compacts sintered with a pressure of 300 MPa and temperatures of 900 °C, were 99.5% dense and had a grain size of 90±24 nm. These are unprecedented results for commercial BaTiO3 powders or any starting powder of 50 nm particle size—other authors have used 16 nm lab-produced powder to obtain similar results.

  16. 100 kW peak power picosecond thulium-doped fiber amplifier system seeded by a gain-switched diode laser at 2 μm.

    PubMed

    Heidt, A M; Li, Z; Sahu, J; Shardlow, P C; Becker, M; Rothhardt, M; Ibsen, M; Phelan, R; Kelly, B; Alam, S U; Richardson, D J

    2013-05-15

    We report on the generation of picosecond pulses at 2 μm directly from a gain-switched discrete-mode diode laser and their amplification in a multistage thulium-doped fiber amplifier chain. The system is capable of operating at repetition rates in the range of 2 MHz-1.5 GHz without change of configuration, delivering high-quality 33 ps pulses with up to 3.5 μJ energy and 100 kW peak power, as well as up to 18 W of average power. These results represent a major technological advance and a 1 order of magnitude increase in peak power and pulse energy compared to existing picosecond sources at 2 μm.

  17. Peak power, ground reaction forces, and velocity during the squat exercise performed at different loads.

    PubMed

    Zink, Attila J; Perry, Arlette C; Robertson, Bobby L; Roach, Kathryn E; Signorile, Joseph F

    2006-08-01

    This study examined the changes in peak power, ground reaction force and velocity with different loads during the performance of the parallel squat movement. Twelve experienced male lifters (26.83 +/- 4.67 years of age) performed the standard parallel squat, using loads equal to 20, 30, 40, 50, 60, 70, 80, and 90% of 1 repetition maximum (1RM). Each subject performed all parallel squats with as much explosiveness as possible using his own technique. Peak power (PP), peak ground reaction force (PGRF), peak barbell velocity (PV), force at the time of PP (FPP), and velocity at the time of PP (VPP) were determined from force, velocity, and power curves calculated using barbell velocity and ground reaction force data. No significant differences were detected among loads for PP; however, the greatest PP values were associated with loads of 40 and 50% of 1RM. Higher loads produced greater PGRF and FPP values than lower loads (p < 0.05) in all cases except between loads equal to 60-50, 50-40, and 40-30% of 1RM for PGRF, and between loads equal to 70-60 and 60-50% of 1RM for FPP. Higher loads produced lower PV and VPP values than lower loads (p < 0.05) in all cases except between the 20-30, 70-80, and 80-90% of 1RM conditions. These results may be helpful in determining loads when prescribing need-specific training protocols targeting different areas of the load-velocity continuum.

  18. Effect of Load on Peak Power of the Bar, Body and System during the Deadlift.

    PubMed

    Blatnik, Justin A; Goodman, Courtney L; Capps, Christopher R; Awelewa, Olumide O; Triplett, Travis N; Erickson, Travis M; McBride, Jeffery M

    2014-09-01

    The purpose of this investigation was to examine how load would affect peak power (PP) of the bar, body and system (bar + body) during the deadlift. Eight healthy males (age = 22.00 ± 2.38 years; height = 1.80 ± 0.05 m; body mass = 88.97 ± 14.88 kg; deadlift one repetition maximum [1RM] = 203.44 ± 21.59 kg, 1RM/BM = 2.32 ± 0.31) with a minimum of 2 years' resistance training experience and a deadlift 1RM over 1.5 times their bodyweight participated in the investigation. During the first session, anthropometric data were recorded and a 1RM deadlift was obtained from the participants. During the second session, participants performed two repetitions at intensities of 30, 40, 50, 60, 70, 80 and 90% of their 1RM in a randomized order. Three-dimensional videography with a force plate was used for data collection and analysis. Peak force (PF), peak velocity (PV), an d PP were calculated for the bar, body, and system (bar + body) during the deadlift. PP occurred at 50%, 30%, and 70% of 1RM for the bar, body, and system, respectively. The optimal loading for the deadlift exercise may vary depending on the desired stimulus and whether the bar, body, or system variables are of most interest. Key pointsPeak power of the bar, body and system vary depending upon load.Loading should be chosen according to desired training effect, with considerations for sport specificity.Additional exercises should be investigated concerning the effect of various loads on power.

  19. Realization and optimization of a 1 ns pulsewidth multi-stage 250 kW peak power monolithic Yb doped fiber amplifier at 1064 nm

    NASA Astrophysics Data System (ADS)

    Morasse, Bertrand; Plourde, Estéban

    2017-02-01

    We present a simple way to achieve and optimize hundreds of kW peak power pulsed output using a monolithic amplifier chain based on solid core double cladding fiber tightly packaged. A fiber pigtailed current driven diode is used to produce nanosecond pulses at 1064 nm. We present how to optimize the use of Fabry-Perot versus DFB type diode along with the proper wavelength locking using a fiber Bragg grating. The optimization of the two pre-amplifiers with respect to the pump wavelength and Yb inversions is presented. We explain how to manage ASE using core and cladding pumping and by using single pass and double pass amplifier. ASE rejection within the Yb fiber itself and with the use of bandpass filter is discussed. Maximizing the amplifier conversion efficiency with regards to the fiber parameters, glass matrix and signal wavelength is described in details. We present how to achieve high peak power at the power amplifier stage using large core/cladding diameter ratio highly doped Yb fibers pumped at 975 nm. The effect of pump bleaching on the effective Yb fiber length is analyzed carefully. We demonstrate that counter-pumping brings little advantage in very short length amplifier. Dealing with the self-pulsation limit of stimulated Brillouin scattering is presented with the adjustment of the seed pulsewidth and linewidth. Future prospects for doubling the output peak power are discussed.

  20. Fast vortex core switching at high temperatures

    NASA Astrophysics Data System (ADS)

    Lebecki, Kristof M.; Legut, Dominik

    2016-08-01

    Fast ferromagnetic vortex core switching is investigated employing micromagnetic simulations. Short pulse (in the range of a few hundreds of picoseconds) of an in-plane oscillating magnetic field is applied to a thin disk (diameter 200 nm and thickness 20 nm) with material parameters resembling permalloy. Fundamental frequency of this excitation field is close to the resonance with the material spin waves. Thermal effects are introduced by replacing the Landau-Lifshitz-Gilbert equation by the Landau-Lifshitz-Bloch equation. Temperature from 300 K to 850 K is considered, just below the Curie temperature TC = 870 K. Calculations are done within the OOMMF simulation framework. We find that: (i) Period of the field necessary to switch the vortex increases approximately from 141 ps at 300 K to 572 ps for the high-temperature limit. (ii) Amplitude of the field necessary to switch the vortex core decreases roughly from 60 mT to 15 mT - even at high temperatures this amplitude is nonzero, contrary to the case of quasi-static switching. (iii) Time span between the excitation and switching (switching time) seems not to depend on the temperature. (iv) Duration of the switching itself (movement of the Bloch point in the sample) increases from a few picoseconds at low temperatures to tens of picoseconds at high temperatures.

  1. Over 1 W record-peak-power operation of a 338 nm AlGaN multiple-quantum-well laser diode on a GaN substrate

    NASA Astrophysics Data System (ADS)

    Taketomi, Hiroyuki; Aoki, Yuta; Takagi, Yasufumi; Sugiyama, Atsushi; Kuwabara, Masakazu; Yoshida, Harumasa

    2016-05-01

    We have demonstrated the high-peak-power operation of an AlGaN-based ultraviolet laser diode (UV-LD) with a lasing wavelength of 338.6 nm. The UV-LD structure was fabricated on a bulk GaN(0001) substrate. The broad-area and vertical conductive structure of the UV-LD, whose ridge width and cavity length were 50 and 600 µm, respectively, was employed. The threshold current density and differential external quantum efficiency were estimated to be 38.9 kA/cm2 and 8.5%, respectively. The characteristic temperature of threshold current was estimated to be 119 K, and the temperature dependence of lasing wavelength was obtained to be 0.033 nm K-1. A peak power of over 1 W has been achieved in 338.6 nm under pulsed operation at room temperature, which is the highest peak power ever obtained for AlGaN-based UV-LDs.

  2. Megawatt-level peak-power from a passively Q-switched hybrid fiber-bulk amplifier and its applications

    NASA Astrophysics Data System (ADS)

    Reiser, Axel; Bdzoch, Juraj; Höfer, Sven; Scholz-Riecke, Sina; Seitz, Daniel; Kugler, Nicolas; Genter, Peter

    2016-03-01

    A novel laser system with optical parameters that fill the gap between Q-switched and modelocked lasers has been developed. It consists of a high gain hybrid fiber-bulk amplifier seeded by a low power SESAM Q-switched oscillator. The mW level output power of the seed oscillator is preamplified by a single mode fiber which is limited by SRS effects. The final amplification stage is realized by a longitudinal pumped Nd:YVO4 crystal in a double pass setup. This MOPA configuration delivers sub-300ps pulses at repetition rates up to 1 MHz with an output power exceeding 60W. Nonlinear frequency conversion to 532nm and 355nm is achieved with efficiencies of >75% and >45%, respectively. Due to the high peak power, high repetition rate and high beam quality of this system, applications formerly only addressable at lower pulse repetition frequencies or with complex modelocked laser systems are now possible with high speed and lower cost of ownership. Application results that take benefit from these new laser parameters will be shown. Furthermore, the reduction of the pulse duration to sub-100ps and power scaling to output powers <100W by the use of the Innoslab concept are being presented.

  3. On Point Designs for High Gain Fast Ignition

    SciTech Connect

    Key, M; Akli, K; Beg, F; Betti, R; Clark, D S; Chen, S N; Freeman, R R; Hansen, S; Hatchett, S P; Hey, D; King, J A; Kemp, A J; Lasinski, B F; Langdon, B; Ma, T; MacKinnon, A J; Meyerhofer, D; Patel, P K; Pasley, J; Phillips, T; Stephens, R B; Stoeckl, C; Foord, M; Tabak, M; Theobald, W; Storm, M; Town, R J; Wilks, S C; VanWoerkom, L; Wei, M S; Weber, R; Zhang, B

    2007-09-27

    Fast ignition research has reached the stage where point designs are becoming crucial to the identification of key issues and the development of projects to demonstrate high gain fast ignition. The status of point designs for cone coupled electron fast ignition and some of the issues they highlight are discussed.

  4. Ubiquinol supplementation enhances peak power production in trained athletes: a double-blind, placebo controlled study

    PubMed Central

    2013-01-01

    Background To investigate the effect of Ubiquinol supplementation on physical performance measured as maximum power output in young and healthy elite trained athletes. Methods In this double-blind, placebo-controlled study, 100 young German well trained athletes (53 male, 47 female, age 19.9 ± 2.3 years) received either 300 mg Ubiquinol or placebo for 6 weeks. Athletes had to perform a maximum power output test and the performance in W/kg of bodyweight was measured at the 4 mmol lactate threshold on a cycling ergometer before the supplementation treatment (T1), after 3 weeks (T2) and after 6 weeks (T3) of treatment. In these 6 weeks all athletes trained individually in preparation for the Olympic Games in London 2012. The maximum power output was measured in Watt/kilogram body weight (W/kg bw). Results Both groups, placebo and Ubiquinol, significantly increased their physical performance measured as maximum power output over the treatment period from T1 to T3. The placebo group increased from 3.64 ± 0.49 W/kg bw to 3.94 ± 0.47 W/kg bw which is an increase of +0.30 ± 0.18 W/kg bw or +8.5% (±5.7). The Ubiquinol group increased performance levels from 3.70 W/kg bw (±0.56) to 4.08 W/kg bw (±0.48) from time point T1 to T3 which is an increase of +0.38 ± 0.22 W/kg bw or +11.0% (±8.2). The absolute difference in the enhancement of the physical performance between the placebo and the Ubiquinol group of +0.08 W/kg bodyweight was significant (p < 0.03). Conclusions This study demonstrates that daily supplementation of 300 mg Ubiquinol for 6 weeks significantly enhanced physical performance measured as maximum power output by +0.08 W/kg bw (+2.5%) versus placebo in young healthy trained German Olympic athletes. While adherence to a training regimen itself resulted in an improvement in peak power output, as observed by improvement in placebo, the effect of Ubiquinol supplementation significantly enhanced peak power production

  5. Behavioral Performance in Monkeys Exposed to Tempo High-Peak-Power Microwave Pulses at 3 GHz.

    DTIC Science & Technology

    1993-12-01

    exposure across all sessions as well as another badge and TLD to measure x-ray exposure during a single session . The cumulative exposure TLD dosimetry...ranges were .543 rem to 1.645 rem (Mean .965, ± .101 SEM). Single session ranges were 0.009 to 0.046 rcm (Mean .016, ± .005 SEM). Statistical Analyses. The

  6. Extremely High Peak Power Pulsed RF and UWB EMR Effects on Genomic Transcription - Microarray Assessment

    DTIC Science & Technology

    2008-06-26

    selenoprotein T 213424_at 2.255 KIAA0895 KIAA0895 protein 210439_at 2.255 ICOS inducible T-cell co-stimulator 201637_s_at 2.252 FXR1 fragile X... mental retardation , autosomal homolog 1 214553_s_at 2.242 ARPP-19 cyclic AMP phosphoprotein, 19 kD 221517_s_at 2.24 CRSP6 cofactor required for Sp1...control, cells were treated with staurosporine (Sigma) for 6 hours at a concentration of 0.5 µg/ml of medium. Western Blot Analysis The p53 protein

  7. Fast diffusion imaging with high angular resolution.

    PubMed

    Chao, Tzu-Cheng; Chiou, Jr-Yuan George; Maier, Stephan E; Madore, Bruno

    2017-02-01

    High angular resolution diffusion imaging (HARDI) is a well-established method to help reveal the architecture of nerve bundles, but long scan times and geometric distortions inherent to echo planar imaging (EPI) have limited its integration into clinical protocols. A fast imaging method is proposed here that combines accelerated multishot diffusion imaging (AMDI), multiplexed sensitivity encoding (MUSE), and crossing fiber angular resolution of intravoxel structure (CFARI) to reduce spatial distortions and reduce total scan time. A multishot EPI sequence was used to improve geometrical fidelity as compared to a single-shot EPI acquisition, and acceleration in both k-space and diffusion sampling enabled reductions in scan time. The method is regularized and self-navigated for motion correction. Seven volunteers were scanned in this study, including four with volumetric whole brain acquisitions. The average similarity of microstructural orientations between undersampled datasets and their fully sampled counterparts was above 85%, with scan times below 5 min for whole-brain acquisitions. Up to 2.7-fold scan time acceleration along with four-fold distortion reduction was achieved. The proposed imaging strategy can generate HARDI results with relatively good geometrical fidelity and low scan duration, which may help facilitate the transition of HARDI from a successful research tool to a practical clinical one. Magn Reson Med 77:696-706, 2017. © 2016 International Society for Magnetic Resonance in Medicine. © 2016 International Society for Magnetic Resonance in Medicine.

  8. Biological maturity-associated variance in peak power output and momentum in academy rugby union players.

    PubMed

    Howard, Sean M A; Cumming, Sean P; Atkinson, Mark; Malina, Robert M

    2016-11-01

    The study aimed to evaluate the mediating effect of biological maturation on anthropometrical measurements, performance indicators and subsequent selection in a group of academy rugby union players. Fifty-one male players 14-17 years of age were assessed for height, weight and BMI, and percentage of predicted mature status attained at the time of observation was used as an indicator of maturity status. Following this, initial sprint velocity (ISV), Wattbike peak power output (PPO) and initial sprint momentum (ISM) were assessed. A bias towards on-time (n = 44) and early (n = 7) maturers was evident in the total sample and magnified with age cohort. Relative to UK reference values, weight and height were above the 90th and 75th centiles, respectively. Significant (p ≤ .01) correlations were observed between maturity status and BMI (r = .48), weight (r = .63) and height (r = .48). Regression analysis (controlling for age) revealed that maturity status and height explained 68% of ISM variance; however, including BMI in the model attenuated the influence of maturity status below statistical significance (p = .72). Height and BMI explained 51% of PPO variance, while no initial significant predictors were identified for ISV. The sample consisted of players who were on-time and early in maturation with no late maturers represented. This was attributable, in part, to the mediating effect of maturation on body size, which, in turn, predicted performance variables.

  9. Kerr self-defocusing of multiple filaments in TW peak power UV laser beam

    NASA Astrophysics Data System (ADS)

    Zvorykin, V. D.; Goncharov, S. A.; Ionin, A. A.; Mokrousova, D. V.; Ryabchuk, S. V.; Seleznev, L. V.; Shutov, A. V.; Smetanin, I. V.; Sunchugasheva, E. S.; Ustinovskii, N. N.

    2016-12-01

    An effective suppression of multiple filamentation of the sub-TW peak power supercritical laser beam in xenon gas was demonstrated in direct amplification of subpicosecond UV pulses at Ti:sapphire/KrF laser facility GARPUN-MTW. A large negative nonlinear refractive index due to a two-photon resonance of KrF laser radiation with Xe 6p{{≤ft[1/2\\right]}0} state ensured Kerr self-defocusing of a few hundred filaments with a local peak intensity of ~0.2 TW cm-2, 200-fold higher than the average one over the beam cross section, and thus homogenized the laser beam. UV filaments in Xe produced a narrow-angle monochromatic coherent cone emission at 828 nm wavelength due to stimulated hyper-Raman scattering and amplified spontaneous emission at the transition 6p{{≤ft[1/2\\right]}0}\\to 6s≤ft[3/2\\right]10 .

  10. Cycling peak power in obese and lean 6- to 8-year-old girls and boys.

    PubMed

    Aucouturier, Julien; Lazaar, Nordine; Doré, Eric; Meyer, Martine; Ratel, Sebastien; Duché, Pascale

    2007-06-01

    The purpose of this study was to investigate the possible effect of the difference in percentage body fat (%BF) and fat-free mass (FFM) on cycling peak power (CPP) in 6- to 8-year-old obese and lean untrained girls and boys. Obese (35 girls, 35 boys) and lean (35 girls, 35 boys) children were measured for obesity, %BF, calculated from skinfold measurements. FFM was calculated as body mass (BM) minus body fat. A force-velocity test on a cycle ergometer was used to measure CPP. CPP was related to anthropometric variables using standard and allometric models. CPP in absolute terms was higher in obese children than in lean children irrespective of gender. BM-related CPP was significantly lower in obese children than in lean ones, whereas no effect of obesity appeared on FFM-related CPP. Velocity at CPP (Vopt) was significantly lower and force at CPP (Fopt) was significantly higher in girls than in boys. Muscle power production was unaffected by obesity in children. Low BM-related CPP could explain the difficulty of taking up physical activities that are body-mass related in obese children. Gender difference for Vopt and Fopt shows that girls and boys may have different maturation patterns affecting CPP.

  11. 500 MW peak power degenerated optical parametric amplifier delivering 52 fs pulses at 97 kHz repetition rate.

    PubMed

    Rothhardt, J; Hädrich, S; Röser, F; Limpert, J; Tünnermann, A

    2008-06-09

    We present a high peak power degenerated parametric amplifier operating at 1030 nm and 97 kHz repetition rate. Pulses of a state-of-the art fiber chirped-pulse amplification (FCPA) system with 840 fs pulse duration and 410 microJ pulse energy are used as pump and seed source for a two stage optical parametric amplifier. Additional spectral broadening of the seed signal in a photonic crystal fiber creates enough bandwidth for ultrashort pulse generation. Subsequent amplification of the broadband seed signal in two 1 mm BBO crystals results in 41 microJ output pulse energy. Compression in a SF 11 prism compressor yields 37 microJ pulses as short as 52 fs. Thus, pulse shortening of more than one order of magnitude is achieved. Further scaling in terms of average power and pulse energy seems possible and will be discussed, since both concepts involved, the fiber laser and the parametric amplifier have the reputation to be immune against thermo-optical effects.

  12. Local oscillator chain for 1.55 to 1.75 THz with 100-(mu)W peak power

    NASA Technical Reports Server (NTRS)

    Maestrini, Alain; Ward, John S.; Javadi, Hamid; Tripon-Canseliet, Charlotte; Gill, John; Chattopadhyay, Goutam; Schlecht, Erich; Mehdi, Imran

    2005-01-01

    We report on the design and performance of a fix-tuned x2x 3x 3 frequency multiplier chain that covers 1.55-1.75 THz. The chain is nominally pumped with 100 mW at W-band. At 120 K the measured output power is larger than 4 (mu)W across the band with a peak power of 100 (mu) W at 1.665 THz. A similar chain operated at room temperature produced a peak power of 21 (mu)W. These power levels now make it possible to deploy multipixel heterodyne imaging arrays in this frequency range.

  13. Peak power, force, and velocity during jump squats in professional rugby players.

    PubMed

    Turner, Anthony P; Unholz, Cedric N; Potts, Neill; Coleman, Simon G S

    2012-06-01

    Training at the optimal load for peak power output (PPO) has been proposed as a method for enhancing power output, although others argue that the force, velocity, and PPO are of interest across the full range of loads. The aim of this study was to examine the influence of load on PPO, peak barbell velocity (BV), and peak vertical ground reaction force (VGRF) during the jump squat (JS) in a group of professional rugby players. Eleven male professional rugby players (age, 26 ± 3 years; height, 1.83 ± 6.12 m; mass, 97.3 ± 11.6 kg) performed loaded JS at loads of 20-100% of 1 repetition maximum (1RM) JS. A force plate and linear position transducer, with a mechanical braking unit, were used to measure PPO, VGRF, and BV. Load had very large significant effects on PPO (p < 0.001, partial η² = 0.915); peak VGRF (p < 0.001, partial η² = 0.854); and peak BV (p < 0.001, partial η² = 0.973). The PPO and peak BV were the highest at 20% 1RM, though PPO was not significantly greater than that at 30% 1RM. The peak VGRF was significantly greater at 1RM than all other loads, with no significant difference between 20 and 60% 1RM. In resistance trained professional rugby players, the optimal load for eliciting PPO during the loaded JS in the range measured occurs at 20% 1RM JS, with decreases in PPO and BV, and increases in VGRF, as the load is increased, although greater PPO likely occurs without any additional load.

  14. Fast Faraday Cup With High Bandwidth

    SciTech Connect

    Deibele, Craig E

    2006-03-14

    A circuit card stripline Fast Faraday cup quantitatively measures the picosecond time structure of a charged particle beam. The stripline configuration maintains signal integrity, and stitching of the stripline increases the bandwidth. A calibration procedure ensures the measurement of the absolute charge and time structure of the charged particle beam.

  15. A few hundred femtosecond FEL with a few kW average and one GW peak power for academic and industrial applications

    NASA Astrophysics Data System (ADS)

    Minehara, Eisuke J.; Hajima, Ryoichi; Sawamura, Masaru; Nagai, Ryoji; Nishimori, Nobuyuki; Kikuzawa, Nobuhiro; Sugimoto, Masayoshi; Yamauchi, Toshihiko; Hayakawa, Taketo; Shizuma, Toshiyuki

    2003-02-01

    The JAERI FEL group has successfully discovered, and realized the brand-new FEL lasing of 255fs ultrafast pulse, 6-9% high-efficiency, one gigawatt high peak power, a few kilowatts average power, and wide tenability of medium and far infrared wavelength regions at the same time. The new lasing was named to be "high-degeneracy superradianct lasing of FEL". Using the new lasing, we could realize a powerful and efficient free-electron laser(FEL) for industrial uses, for examples, pharmacy, medical, defense, shipbuilding, semiconductor industry, chemical industries, environmental sciences, space-debris, power beaming and so on. In order to realize such a tunable, highly-efficient, high average power, high peak power and ultra-short pulse FEL, we need the efficient and powerful FEL driven by JAERI compact, stand-alone and zero-boil-off super-conducting rf linac with an energy-recovery geometry. Our discussions on the FEL will cover market-requirements and roadmap for the industrial FELs, some answers from the JAERI compact, stand-alone and zero-boil-off cryostat concept and operational experience over these 10 years, our discovery of the new highly-efficient, high-power, and ultra-short pulse lasing mode, and the energy-recovery geometry.

  16. Phase-matched waveguide four-wave mixing scaled to higher peak powers with large-core-area hollow photonic-crystal fibers.

    PubMed

    Konorov, S O; Serebryannikov, E E; Fedotov, A B; Miles, R B; Zheltikov, A M

    2005-05-01

    Hollow photonic-crystal fibers with large core diameters are shown to allow waveguide nonlinear-optical interactions to be scaled to higher pulse peak powers. Phase-matched four-wave mixing is predicted theoretically and demonstrated experimentally for millijoule nanosecond pulses propagating in a hollow photonic-crystal fiber with a core diameter of about 50 microm , suggesting the way to substantially enhance the efficiency of nonlinear-optical spectral transformations and wave mixing of high-power laser pulses in the gas phase.

  17. Short-pulse MOPA fiber laser with kilowatt average power and multi-megawatt peak power, applying advanced XLMA fiber amplifiers

    NASA Astrophysics Data System (ADS)

    Dinger, R.; Grundmann, F.-P.; Hapke, C.; Kallage, P.; Rath, W.; Ruppik, S.

    2017-03-01

    High power short pulse fiber lasers are applied in industry for many ablation processes or various surface treatments, and there is a huge demand for such lasers but with higher average power, higher pulse energy and higher peak power. This contribution presents a high peak- and average- power fiber laser with selectable pulse durations between 10 ns and 100 ns, where more than 150 mJ pulse energy has been achieved at a repetition rate of 10 kHz. In addition, for a laser pulse with 30 ns pulse duration a maximum peak power of more than 3.5 MW at more than 1 kW average output power have been demonstrated. These results could be achieved by applying extra-large mode area (XLMA) gain fibers (fiber core <100 μm) in the fiber amplifiers and using pulse shape capabilities of the seed laser, only. Stable and safe operation of the fiber laser have been shown with power densities up to 3 GW/cm² in the gain fiber. In order to protect the fiber laser to be affected by back reflections from the workpiece, a newly designed optical isolator with more than 30 dB isolation has been implemented.

  18. Effect of cadence selection on peak power and time of power production in elite BMX riders: A laboratory based study.

    PubMed

    Rylands, Lee P; Roberts, Simon J; Hurst, Howard T; Bentley, Ian

    2017-07-01

    The aims of this study were to analyse the optimal cadence for peak power production and time to peak power in bicycle motocross (BMX) riders. Six male elite BMX riders volunteered for the study. Each rider completed 3 maximal sprints at a cadence of 80, 100, 120 and 140 revs · min(-1) on a laboratory Schoberer Rad Messtechnik (SRM) cycle ergometer in isokinetic mode. The riders' mean values for peak power and time of power production in all 3 tests were recorded. The BMX riders produced peak power (1105 ± 139 W) at 100 revs · min(-1) with lower peak power produced at 80 revs · min(-1) (1060 ± 69 W, (F(2,15) = 3.162; P = .266; η(2) = 0.960), 120 revs · min(-1) (1077 ± 141 W, (F(2,15) = 4.348; P = .203; η(2) = 0.970) and 140 revs · min(-1) (1046 ± 175 W, (F(2,15) = 12.350; P = 0.077; η(2) = 0.989). The shortest time to power production was attained at 120 revs · min(-1) in 2.5 ± 1.07 s. Whilst a cadence of 80 revs · min(-1) (3.5 ± 0.8 s, (F(2,15) = 2.667; P = .284; η(2) = 0.800) 100 revs · min(-1) (3.00 ± 1.13 s, (F(2,15) = 24.832; P = .039; η(2) = 0.974) and 140 revs · min(-1) (3.50 ± 0.88 s, (F(2,15) = 44.167; P = .006; η(2) = 0.967)) all recorded a longer time to peak power production. The results indicate that the optimal cadence for producing peak power output and reducing the time to peak power output are attained at comparatively low cadences for sprint cycling events. These findings could potentially inform strength and conditioning training to maximise dynamic force production and enable coaches to select optimal gear ratios.

  19. Yb3+-doped rod-type amplifiers with local adiabatic tapers for peak power scaling and beam quality improvement

    NASA Astrophysics Data System (ADS)

    Zhu, Yuan; Eschrich, Tina; Leich, Martin; Grimm, Stephan; Kobelke, Jens; Lorenz, Martin; Bartelt, Hartmut; Jäger, Matthias

    2017-10-01

    The use of short local tapers in large mode area fiber amplifiers is proposed for peak power scaling while maintaining good beam quality. To avoid modal distortions, the powder-sintering (REPUSIL) method was employed to obtain core materials with excellent refractive index homogeneity. First experiments with Yb3+-doped rod-type amplifiers delivered 2 ns pulses with peak powers of 540 kW and energies of 1.4 mJ for the untapered rod and 230 kW for the tapered rod (limited by facet damage). The beam quality improved from an M 2 value of approximately 10 to 3.5. The investigation of the taper structure indicates room for further improvement.

  20. Fast-Recovery, High-Voltage Power Diode

    NASA Technical Reports Server (NTRS)

    Sundberg, G.; Berman, A.; Balodis, V.; Gaugh, C.; Duffin, J.; Karatnicki, H.; Larson, E.

    1985-01-01

    New family of fast-recovery high-voltage power diodes compatible with D60T and D7ST transistors developed. Have wide range of applications in spacecraft and aircraft electrical distribution equipment, dc/dc inverters, and ac motor controllers for high-horsepower electric motors operating from 480-volt ac lines. Fast-Recovery 1,200-V Power Diodes use chip of hexagonal geometry to maximize effective silicon area.

  1. Broadband supercontinuum generation in lead silicate photonic crystal fibers employing optical pulses of 50 W peak power

    NASA Astrophysics Data System (ADS)

    Sharma, Mohit; Konar, S.

    2016-12-01

    A unique solid core lead silicate photonic crystal fiber has been designed which promises to simultaneously exhibit large optical nonlinearity and almost uniform low dispersion. At 1064 and 1550 nm wavelengths, the fiber is expected to exhibit nonlinear coefficient ~ 1420 W-1 km-1 and ~ 923 W-1 km-1, respectively, and dispersion ~ 7 ps/km/nm and ~ 40 ps/km/nm, respectively. Employing numerical simulation, we have investigated supercontinuum (SC) generation in this fiber by pumping 1 ps and 50 fs pulses. An octave-spanning SC from 680 to 1500 nm is achievable at the end of 15 cm long fiber by pumping 50 fs pulses of 50 W peak power at 1064 nm. SC spectra from 1200 to 2600 nm are also achievable by pumping 50 fs pulses of 100 W peak power at 1550 nm. The simulated SC spectra due to 50 fs pulses are attributed to self-phase modulation. A flat spectrum from 650 to 980 nm is predicted due to pumping in the normal dispersion regime at 800 nm using 1 ps pulses of 300 W peak power in a 75 cm long fiber.

  2. Thin-disk multipass amplifier for fs pulses delivering 400 W of average and 2.0 GW of peak power for linear polarization as well as 235 W and 1.2 GW for radial polarization

    NASA Astrophysics Data System (ADS)

    Negel, Jan-Philipp; Loescher, André; Dannecker, Benjamin; Oldorf, Paul; Reichel, Stefanie; Peters, Rigo; Abdou Ahmed, Marwan; Graf, Thomas

    2017-05-01

    We report on an Yb:YAG thin-disk multipass amplifier delivering linearly polarized laser pulses with a pulse duration of 885 fs at an average output power of 400 W and a repetition rate of 200 kHz, corresponding to a peak power of 2.0 GW. This is the highest average output power reported for thin-disk multipass amplifiers delivering pulses with peak powers in excess of 1 GW and it confirms the suitability of thin-disk multipass amplifiers to reach high average output and peak powers at the same time. The amplifier was seeded by a regenerative amplifier delivering laser pulses with a pulse duration of 805 fs and an average power of 40 W. We investigated the influence of self-phase-modulation on the amplified beam and compared it to results with lower peak intensities at a repetition rate of 800 kHz. Furthermore, we report on the amplification of a radially polarized beam leading to 235 W of average output power and 1.2 GW of peak power (at a pulse duration of 888 fs). To the best of our knowledge, this is the highest average output power demonstrated so far for radially polarized GW peak-level laser pulses.

  3. Fast damping in mismatched high intensity beam transportation

    NASA Astrophysics Data System (ADS)

    Variale, V.

    2001-08-01

    A very fast damping of beam envelope oscillation amplitudes was recently observed in simulations of high intensity beam transport, through periodic FODO cells, in mismatched conditions [V. Variale, Nuovo Cimento Soc. Ital. Fis. 112A, 1571-1582 (1999) and T. Clauser et al., in Proceedings of the Particle Accelerator Conference, New York, 1999 (IEEE, Piscataway, NJ, 1999), p. 1779]. A Landau damping mechanism was proposed at the origin of observed effect. In this paper, to further investigate the source of this fast damping, extensive simulations have been carried out. The results presented here support the interpretation of the mechanism at the origin of the fast damping as a Landau damping effect.

  4. Isolated Fast High-Voltage Switching Circuit

    NASA Technical Reports Server (NTRS)

    Rizzi, Anthony

    1992-01-01

    Electrically isolated switching circuit supplies pulses at potentials up to 6.5 kV and currents up to 6.5 A, lasting as long as few microseconds. Turn-on time about 40 ns; turn-off time about 3 microseconds. Electrically isolated from control circuitry by means of fiber-optic signal coupling and isolated power supply. Electrical isolation protects both technician and equipment. This and similar circuits useful in such industrial and scientific applications as high-voltage, high-frequency test equipment; electrostatic-discharge test equipment; plasma-laboratory instrumentation; spark chambers; and electromagnetic-interference test equipment.

  5. Highly accurate fast lung CT registration

    NASA Astrophysics Data System (ADS)

    Rühaak, Jan; Heldmann, Stefan; Kipshagen, Till; Fischer, Bernd

    2013-03-01

    Lung registration in thoracic CT scans has received much attention in the medical imaging community. Possible applications range from follow-up analysis, motion correction for radiation therapy, monitoring of air flow and pulmonary function to lung elasticity analysis. In a clinical environment, runtime is always a critical issue, ruling out quite a few excellent registration approaches. In this paper, a highly efficient variational lung registration method based on minimizing the normalized gradient fields distance measure with curvature regularization is presented. The method ensures diffeomorphic deformations by an additional volume regularization. Supplemental user knowledge, like a segmentation of the lungs, may be incorporated as well. The accuracy of our method was evaluated on 40 test cases from clinical routine. In the EMPIRE10 lung registration challenge, our scheme ranks third, with respect to various validation criteria, out of 28 algorithms with an average landmark distance of 0.72 mm. The average runtime is about 1:50 min on a standard PC, making it by far the fastest approach of the top-ranking algorithms. Additionally, the ten publicly available DIR-Lab inhale-exhale scan pairs were registered to subvoxel accuracy at computation times of only 20 seconds. Our method thus combines very attractive runtimes with state-of-the-art accuracy in a unique way.

  6. Microexternal cavity tapered lasers at 670 nm with 5 W peak power and nearly diffraction-limited beam quality.

    PubMed

    Tien, Tran Quoc; Maiwald, Martin; Sumpf, Bernd; Erbert, Götz; Tränkle, Günther

    2008-11-15

    Wavelength-stabilized compact laser systems at 670 nm on a micro-optical bench are presented. The resonator concept consists of a tapered semiconductor gain medium and a reflection Bragg grating as a wavelength selective resonator mirror. In pulse operation mode with 100 ns pulses, an optical peak power of 5 W with a spectral width below 150 pm was achieved. Nearly diffraction-limited beam quality at optical output powers up to 1 W is obtained. Such laser systems can be used, e.g., for Raman spectroscopy and as pumping sources for frequency conversion toward UV spectral range.

  7. Scaling of dissipative soliton fiber lasers to megawatt peak powers by use of large-area photonic crystal fiber

    PubMed Central

    Lefrançois, Simon; Kieu, Khanh; Deng, Yujun; Kafka, James D.; Wise, Frank W.

    2011-01-01

    We report an all-normal dispersion femtosecond laser based on large-mode-area Yb-doped photonic crystal fiber. Self-starting mode-locked pulses are obtained with an average power of 12 W at 84 MHz repetition rate, corresponding to 140 nJ of chirped pulse energy. These are dechirped to a near transform-limited duration of 115 fs. Experimental results are consistent with numerical simulations of dissipative soliton intracavity pulse evolution, and demonstrate scaling of 100 fs pulses to megawatt peak powers. PMID:20479811

  8. Frequency-tunable sub-two-cycle 60-MW-peak-power free-space waveforms in the mid-infrared.

    PubMed

    Lanin, A A; Voronin, A A; Stepanov, E A; Fedotov, A B; Zheltikov, A M

    2014-11-15

    A physical scenario whereby freely propagating mid-infrared pulses can be compressed to pulse widths close to the field cycle is identified. Generation of tunable few-cycle pulses in the wavelength range from 4.2 to 6.8 μm is demonstrated at a 1-kHz repetition rate through self-focusing-assisted spectral broadening in a normally dispersive, highly nonlinear semiconductor material, followed by pulse compression in the regime of anomalous dispersion, where the dispersion-induced phase shift is finely tuned by adjusting the overall thickness of anomalously dispersive components. Sub-two-cycle pulses with a peak power up to 60 MW are generated in the range of central wavelengths tunable from 5.9 to 6.3 μm.

  9. A simple algorithm to compute the peak power output of GaAs/Ge solar cells on the Martian surface

    SciTech Connect

    Glueck, P.R.; Bahrami, K.A.

    1995-12-31

    The Jet Propulsion Laboratory`s (JPL`s) Mars Pathfinder Project will deploy a robotic ``microrover`` on the surface of Mars in the summer of 1997. This vehicle will derive primary power from a GaAs/Ge solar array during the day and will ``sleep`` at night. This strategy requires that the rover be able to (1) determine when it is necessary to save the contents of volatile memory late in the afternoon and (2) determine when sufficient power is available to resume operations in the morning. An algorithm was developed that estimates the peak power point of the solar array from the solar array short-circuit current and temperature telemetry, and provides functional redundancy for both measurements using the open-circuit voltage telemetry. The algorithm minimizes vehicle processing and memory utilization by using linear equations instead of look-up tables to estimate peak power with very little loss in accuracy. This paper describes the method used to obtain the algorithm and presents the detailed algorithm design.

  10. Visualizing fast electron energy transport into laser-compressed high-density fast-ignition targets

    NASA Astrophysics Data System (ADS)

    Jarrott, L. C.; Wei, M. S.; McGuffey, C.; Solodov, A. A.; Theobald, W.; Qiao, B.; Stoeckl, C.; Betti, R.; Chen, H.; Delettrez, J.; Döppner, T.; Giraldez, E. M.; Glebov, V. Y.; Habara, H.; Iwawaki, T.; Key, M. H.; Luo, R. W.; Marshall, F. J.; McLean, H. S.; Mileham, C.; Patel, P. K.; Santos, J. J.; Sawada, H.; Stephens, R. B.; Yabuuchi, T.; Beg, F. N.

    2016-05-01

    Recent progress in kilojoule-scale high-intensity lasers has opened up new areas of research in radiography, laboratory astrophysics, high-energy-density physics, and fast-ignition (FI) laser fusion. FI requires efficient heating of pre-compressed high-density fuel by an intense relativistic electron beam produced from laser-matter interaction. Understanding the details of electron beam generation and transport is crucial for FI. Here we report on the first visualization of fast electron spatial energy deposition in a laser-compressed cone-in-shell FI target, facilitated by doping the shell with copper and imaging the K-shell radiation. Multi-scale simulations accompanying the experiments clearly show the location of fast electrons and reveal key parameters affecting energy coupling. The approach provides a more direct way to infer energy coupling and guide experimental designs that significantly improve the laser-to-core coupling to 7%. Our findings lay the groundwork for further improving efficiency, with 15% energy coupling predicted in FI experiments using an existing megajoule-scale laser driver.

  11. Dual-wavelength tunable fibre laser with a 15-dBm peak power

    SciTech Connect

    Latif, A A; Awang, N A; Zulkifli, M Z; Harun, S W; Ghani, Z A; Ahmad, H

    2011-08-31

    A high-power dual-wavelength tunable fibre laser (HP-DWTFL) operating in the C-band at wavelengths from 1536.7 nm to 1548.6 nm is proposed and demonstrated. The HP-DWTFL utilises an arrayed waveguide grating (AWG) (1 x 16 channels) and is capable of generating eight different dual-wavelength pairs with eight possible wavelength spacings ranging from 0.8 nm (the narrowest spacing) to 12.0 nm (the widest spacing). The average output power and side mode suppression ratio (SMSR) of the HP-DWTFL are measured to be 15 dBm and 52.55 dB, respectively. The proposed HP-DWTFL is highly stable with no variations in the chosen output wavelengths and has minimal changes in the output power. Such a laser has good potential for use in measurements, communications, spectroscopy and terahertz applications. (control of radiation parameters)

  12. Superradiant Ka-band Cherenkov oscillator with 2-GW peak power

    NASA Astrophysics Data System (ADS)

    Rostov, V. V.; Romanchenko, I. V.; Pedos, M. S.; Rukin, S. N.; Sharypov, K. A.; Shpak, V. G.; Shunailov, S. A.; Ul'masculov, M. R.; Yalandin, M. I.

    2016-09-01

    The generation of a 2-GW microwave superradiance (SR) pulses has been demonstrated at 29-GHz using a single-mode relativistic backward-wave oscillator possessing the beam-to-wave power conversion factor no worse than 100%. A record-breaking radiation power density in the slow-wave structure (SWS) of ˜1.5 GW/cm2 required the use of high guiding magnetic field (7 T) decreasing the beam losses to the SWS in strong rf fields. Despite the field strength at the SWS wall of 2 MV/cm, a single-pass transmission mode of a short SR pulse in the SWS allows one to obtain extremely high power density in subnanosecond time scale due to time delay in the development of the breakdown phenomena.

  13. Superradiant Ka-band Cherenkov oscillator with 2-GW peak power

    SciTech Connect

    Rostov, V. V.; Romanchenko, I. V.; Pedos, M. S.; Rukin, S. N.; Sharypov, K. A.; Shpak, V. G.; Shunailov, S. A.; Ul'masculov, M. R.; Yalandin, M. I.

    2016-09-15

    The generation of a 2-GW microwave superradiance (SR) pulses has been demonstrated at 29-GHz using a single-mode relativistic backward-wave oscillator possessing the beam-to-wave power conversion factor no worse than 100%. A record-breaking radiation power density in the slow-wave structure (SWS) of ∼1.5 GW/cm{sup 2} required the use of high guiding magnetic field (7 T) decreasing the beam losses to the SWS in strong rf fields. Despite the field strength at the SWS wall of 2 MV/cm, a single-pass transmission mode of a short SR pulse in the SWS allows one to obtain extremely high power density in subnanosecond time scale due to time delay in the development of the breakdown phenomena.

  14. Fast Neutron Irradiation of the Highly Radioresistant Bacterium Deinococcus Radiodurans

    NASA Astrophysics Data System (ADS)

    Case, Diane Louise

    Fast neutron dose survival curves were generated for the bacterium Deinococcus radiodurans, which is renowned for its unusually high resistance to gamma, x-ray, and ultraviolet radiation, but for which fast neutron response was unknown. The fast neutrons were produced by the University of Massachusetts Lowell 5.5-MV, type CN Van de Graaff accelerator through the ^7Li(p,n)^7 Be reaction by bombarding a thick metallic lithium target with a 4-MeV proton beam. The bacteria were uniformly distributed on 150-mm agar plates and were exposed to the fast neutron beam under conditions of charged particle equilibrium. The plates were subdivided into concentric rings of increasing diameter from the center to the periphery of the plate, within which the average neutron dose was calculated as the product of the precisely known neutron fluence at the average radius of the ring and the neutron energy dependent kerma factor. The neutron fluence and dose ranged from approximately 3 times 1013 n cm^ {-2} to 1 times 1012 n cm^ {-2}, and 200 kilorad to 5 kilorad, respectively, from the center to the periphery of the plate. Percent survival for Deinococcus radiodurans as a function of fast neutron dose was derived from the ability of the irradiated cells to produce visible colonies within each ring compared to that of a nonirradiated control population. The bacterium Escherichia coli B/r (CSH) was irradiated under identical conditions for comparative purposes. The survival response of Deinococcus radiodurans as a result of cumulative fast neutron exposures was also investigated. The quantification of the ability of Deinococcus radiodurans to survive cellular insult from secondary charged particles, which are produced by fast neutron interactions in biological materials, will provide valuable information about damage and repair mechanisms under extreme cellular stress, and may provide new insight into the origin of this bacterium's unprecedented radiation resistance.

  15. Chair Rise Peak Power in Daily Life Measured With a Pendant Sensor Associates With Mobility, Limitation in Activities, and Frailty in Old People.

    PubMed

    Zhang, Wei; Regterschot, G Ruben H; Geraedts, Hilde; Baldus, Heribert; Zijlstra, Wiebren

    2017-01-01

    The aim of this study was to analyze the clinical relevance of sensor-based daily life chair rise performance measured in old people. A pendant-sensor was worn during standardized tests and in daily life to detect chair rise transfers and analyze transfer peak power. Linear correlations between mean, median, 25th, and 75th percentile transfer peak powers in daily life and mean peak power in standardized tests were evaluated with Pearson correlation ( r). Associations between transfer peak powers in different experiments and outcomes of a clinical mobility test [timed-up-and-go (TUG)], a test of limitation in activities [Groningen activity restriction scale (GARS)], and a frailty test [Groningen frailty indicator (GFI)] were evaluated with Spearman correlation (ρ). Twenty-five old people (70-85 years) participated in the study. The results showed that chair rise peak powers assessed based upon one-week of daily life activities significantly correlated with peak power measured in standardized tests (r: [0.66, 0.74], p < 0.01). Chair rise peak power in daily life significantly associated with TUG scores (ρ: [-0.71, -0.58], ), GARS (ρ: [-0.62, -0.48], ), and GFI (ρ: [-0.52, -0.43], ). Chair rise peak powers in daily life had stronger associations with clinical measurements than standardized tests. In addition, chair rise peak powers measured in old people using assistive devices was significantly lower compared to those not using assistive devices. These results indicate usefulness of the pendant-sensor-based chair rise performance analysis in continuous monitoring and assessment of mobility, limitations in activities and frailty associated variables in old people's daily life.

  16. Transfer ionization in collisions with a fast highly charged ion.

    PubMed

    Voitkiv, A B

    2013-07-26

    Transfer ionization in fast collisions between a bare ion and an atom, in which one of the atomic electrons is captured by the ion whereas another one is emitted, crucially depends on dynamic electron-electron correlations. We show that in collisions with a highly charged ion a strong field of the ion has a very profound effect on the correlated channels of transfer ionization. In particular, this field weakens (strongly suppresses) electron emission into the direction opposite (perpendicular) to the motion of the ion. Instead, electron emission is redirected into those parts of the momentum space which are very weakly populated in fast collisions with low charged ions.

  17. AEC brings new technology to US: Compressed air provides peaking power

    SciTech Connect

    Not Available

    1989-09-01

    The first power plant utilizing compressed air energy storage technology (CAES) in the United States is being built by Alabama Electric Cooperative near McIntosh, Alabama. CAES technology, which stores pressurized air in underground chambers during periods of low power demand for generating power during high demand periods, is capable of producing up to three times more power per BTU of fuel burned than conventional gas turbine generators. A 19 million-cubic foot air storage cavern is being excavated in a salt dome 1,400 feet underground for the 110 MW McIntosh plant. Once finished, the cavern is expected to be 200 feet in diameter and 600 feet deep, storing enough air to operate the generator for 26 consecutive hours.

  18. Multi-tens of GW peak power plasma-based soft x-ray laser

    NASA Astrophysics Data System (ADS)

    Oliva, E.; Fajardo, M.; Li, L.; Le, T. T. T.; Ros, D.; Sebban, S.; Velarde, P.; Zeitoun, P.

    2013-09-01

    Ultra-intense X-ray sources have opened new avenues by creating new states of matter or probing and imaging living or inert matter. Free-electron lasers have a strong leadership by delivering pulses combining femtosecond duration and 10s of microJoules to milliJoule energy. However, these sources remain highly expensive limiting their number to a few worldwide. In parallel, laser-pumped soft X-ray lasers hold outstanding promises having demonstrated the most energetic monochromatic soft x-ray pulse and being intrinsically fully synchronized with any secondary source of the pump laser. Since the first successful demonstration of amplification of a high harmonic pulse in a plasma from gas in 2003 and from solid in 2008, we have developed an extensive numerical study. 2D hydrodynamic simulations showed that optimized Transient Collisional Excitation plasma amplifiers, may store up to 0.4 mJ in the population inversion. If carefully seeded, pulses of 80 fs and 20 μJ might be generated with table-top lasers (10J). As the energy extracted is far from the milliJoule requirements of most exciting applications, we studied the seminal experiment of Ditmire et al who seeded a plasma emitting milliJoules in the form of Amplified Spontaneous Emission (ASE).We retrieved and explained for the first time the experimental result (ASE 1,000 times stronger than amplified seed). We thus proposed and fully modeled the transposition of the so-called Chirped Pulse Amplification (CPA) in the soft X-ray range, showing that 6 mJ, 200 fs, fully coherent soft X-ray pulse is accessible with compact pump lasers.

  19. Optimized Scheduling Technique of Null Subcarriers for Peak Power Control in 3GPP LTE Downlink

    PubMed Central

    Park, Sang Kyu

    2014-01-01

    Orthogonal frequency division multiple access (OFDMA) is a key multiple access technique for the long term evolution (LTE) downlink. However, high peak-to-average power ratio (PAPR) can cause the degradation of power efficiency. The well-known PAPR reduction technique, dummy sequence insertion (DSI), can be a realistic solution because of its structural simplicity. However, the large usage of subcarriers for the dummy sequences may decrease the transmitted data rate in the DSI scheme. In this paper, a novel DSI scheme is applied to the LTE system. Firstly, we obtain the null subcarriers in single-input single-output (SISO) and multiple-input multiple-output (MIMO) systems, respectively; then, optimized dummy sequences are inserted into the obtained null subcarrier. Simulation results show that Walsh-Hadamard transform (WHT) sequence is the best for the dummy sequence and the ratio of 16 to 20 for the WHT and randomly generated sequences has the maximum PAPR reduction performance. The number of near optimal iteration is derived to prevent exhausted iterations. It is also shown that there is no bit error rate (BER) degradation with the proposed technique in LTE downlink system. PMID:24883376

  20. Optimized scheduling technique of null subcarriers for peak power control in 3GPP LTE downlink.

    PubMed

    Cho, Soobum; Park, Sang Kyu

    2014-01-01

    Orthogonal frequency division multiple access (OFDMA) is a key multiple access technique for the long term evolution (LTE) downlink. However, high peak-to-average power ratio (PAPR) can cause the degradation of power efficiency. The well-known PAPR reduction technique, dummy sequence insertion (DSI), can be a realistic solution because of its structural simplicity. However, the large usage of subcarriers for the dummy sequences may decrease the transmitted data rate in the DSI scheme. In this paper, a novel DSI scheme is applied to the LTE system. Firstly, we obtain the null subcarriers in single-input single-output (SISO) and multiple-input multiple-output (MIMO) systems, respectively; then, optimized dummy sequences are inserted into the obtained null subcarrier. Simulation results show that Walsh-Hadamard transform (WHT) sequence is the best for the dummy sequence and the ratio of 16 to 20 for the WHT and randomly generated sequences has the maximum PAPR reduction performance. The number of near optimal iteration is derived to prevent exhausted iterations. It is also shown that there is no bit error rate (BER) degradation with the proposed technique in LTE downlink system.

  1. High performance pipelined multiplier with fast carry-save adder

    NASA Technical Reports Server (NTRS)

    Wu, Angus

    1990-01-01

    A high-performance pipelined multiplier is described. Its high performance results from the fast carry-save adder basic cell which has a simple structure and is suitable for the Gate Forest semi-custom environment. The carry-save adder computes the sum and carry within two gate delay. Results show that the proposed adder can operate at 200 MHz for a 2-micron CMOS process; better performance is expected in a Gate Forest realization.

  2. High power, fast, microwave components based on beam generated plasmas

    NASA Astrophysics Data System (ADS)

    Manheimer, W. M.; Fernsler, R. F.; Gitlin, M. S.

    1998-10-01

    It is shown that the agile mirror plasma, under development as a device to simply and cheaply give electronic steering to microwave beams, also has application as a fast, electronically controlled, high power reflector, or phase shifter. In a radar system, this can lead to such applications as pulse to pulse polarization agility and electronic control of antenna gain, as well as to innovative approaches to high power millimeter wave circulators. The basic theory of the enhanced glow plasma is also developed.

  3. Peak power minimization in indoor CDMA communications using clusters of antennas

    NASA Astrophysics Data System (ADS)

    Abolhassani, Bahman

    "Battery life" and "cost" constraints are presenting new challenges for the design of wireless networks. The major focus of past research on transmit power control, diversity, modulation and coding techniques has been limited to maximizing coverage and/or capacity for cellular telephone systems. However, for battery powered wireless handsets connected through indoor wireless links, the optimization objective is shifting from link efficiency to battery efficiency and cost. In this thesis, the battery life of handsets and the cost of network are both addressed for an indoor code division multiple access (CDMA) communications system using time division duplex (TDD). A wireless handset needs a large dynamic range transmitter amplifier in order to overcome channel path loss and fading. This makes the amplifier inefficient such that its power consumption becomes proportional to the peak transmit power. Therefore, the amplifier needs a large, heavy and expensive battery which lasts for only a few hours. Indoor wireless users, however, need small, light, low cost handsets with batteries that last for days rather than for a few hours. To achieve a long battery life for handsets, a system architecture is proposed in which each cell uses a central base station along with several radioports. The radioports placed at optimal or near-optimal locations in order to minimize the maximum path loss experienced by handsets. Each radioport may use more than one antenna to combat Rayleigh fading. The central base station selects the radioport that provides the strongest maximally ratio combined signal. An infra-structure cost model is developed for the proposed system, which depends on the peak transmit power capability of handsets and of other system parameters and performances. The number of parameters affecting the network infra-structure cost is high, which makes the cost minimization problematic. To avoid large computation time, a new network planning approach is proposed: its

  4. Fast-ion studies in the National Spherical Torus Experiment: Transport by instabilities and acceleration by high harmonic fast waves

    NASA Astrophysics Data System (ADS)

    Liu, Deyong

    2009-12-01

    An extensive set of fast-ion diagnostics, including neutron detectors, a E∣∣B type neutral particle analyzer (NPA) and the newly built four-chord solid state neutral particle analyzer array (SSNPA) and a 16-channel Fast-ion D-alpha (FIDA) diagnostic, provides a good test-bed to study fast ion physics in the National Spherical Torus Experiment (NSTX). During combined neutral beam injection (NBI) and High-Harmonic Fast-Wave (HHFW) heating, the acceleration of fast ions is evident in all fast ion diagnostics. The neutron rate is about three times larger during the HHFW heating. A fast-ion tail above the beam injection is observed in the NPA, SSNPA and FIDA diagnostics. It is also shown that the accelerated fast ions observed by the NPA and SSNPA diagnostics mainly come from passive charge exchange reactions at the edge due to the NPA/SSNPA localization in phase space. The spatial profile of accelerated fast ions that is measured by the FIDA diagnostic is much broader than in conventional tokamaks because of the multiple resonance layers and large orbits in NSTX. The fast-ion distribution function calculated by the CQL3D Fokker-Planck code differs from the measured spatial profile, presumably because the current version of CQL3D uses a zero-banana-width model. In addition, the effects of bursting instabilities on the fast ion distribution in neutral beam heated plasmas are examined. Fishbone events generally have a minor effect on the fast ion distribution and no clear correlation is observed in the NPA and SSNPA diagnostics. However, sawteeth or the combinations of fishbones and CAEs always cause neutron rate drops up to 25% and bursts at outer chords of the SSNPA, which indicate fast ion loss. It is also observed that high energy fast ions respond earlier than low energy fast ions.

  5. 1.6  MW peak power, 90  ps all-solid-state laser from an aberration self-compensated double-passing end-pumped Nd:YVO4 rod amplifier.

    PubMed

    Wang, Chunhua; Liu, Chong; Shen, Lifeng; Zhao, Zhiliang; Liu, Bin; Jiang, Hongbo

    2016-03-20

    In this paper a delicately designed double-passing end-pumped Nd:YVO4 rod amplifier is reported that produces 10.2 W average laser output when seeded by a 6 mW Nd:YVO4 microchip laser at a repetition rate of 70 kHz with pulse duration of 90 ps. A pulse peak power of ∼1.6  MW and pulse energy of ∼143  μJ is achieved. The beam quality is well preserved by a double-passing configuration for spherical-aberration compensation. The laser-beam size in the amplifier is optimized to prevent the unwanted damage from the high pulse peak-power density. This study provides a simple and robust picosecond all-solid-state master oscillator power amplifier system with both high peak power and high beam quality, which shows great potential in the micromachining.

  6. The Nexawatt: A Strategy for Exawatt Peak Power Lasers Based on NIF and NIF-like Beam Lines

    NASA Astrophysics Data System (ADS)

    Barty, C. P. J.

    2016-05-01

    An exawatt-scale, short-pulse amplification architecture based upon a novel pulse compressor arrangement and amplification of long-duration chirped beam pulses is described. This architecture is capable of extracting the full, stored energy of a NIF or NIF-like beam line and in doing so produce from one beam line a near-diffraction-limited, laser pulse whose peak power would exceed 0.2 EW. The architecture is well suited to either low-f-number focusing or to multi-beam, dipole focusing concepts that in principle enable focused intensities in the range of 1026 W/cm2 or 5 orders of magnitude beyond that possible from present PW systems based on chirped pulse amplification.

  7. Unilateral fluid absorption and effects on peak power after ingestion of commercially available hypotonic, isotonic, and hypertonic sports drinks.

    PubMed

    Rowlands, David S; Bonetti, Darrell L; Hopkins, Will G

    2011-12-01

    Isotonic sports drinks are often consumed to offset the effects of dehydration and improve endurance performance, but hypotonic drinks may be more advantageous. The purpose of the study was to compare absorption and effects on performance of a commercially available hypotonic sports drink (Mizone Rapid: 3.9% carbohydrate [CHO], 218 mOsmol/kg) with those of an isotonic drink (PowerAde: 7.6% CHO, 281 mOsmol/ kg), a hypertonic drink (Gatorade: 6% CHO, 327 mOsmol/kg), and a noncaloric placebo (8 mOsmol/kg). In a crossover, 11 cyclists consumed each drink on separate days at 250 ml/15 min during a 2-hr preload ride at 55% peak power followed by an incremental test to exhaustion. Small to moderate increases in deuterium oxide enrichment in the preload were observed with Mizone Rapid relative to PowerAde, Gatorade, and placebo (differences of 88, 45, and 42 parts per million, respectively; 90% confidence limits ±28). Serum osmolality was moderately lower with Mizone Rapid than with PowerAde and Gatorade (-1.9, -2.4; mOsmol/L; ±1.2 mOsmol/L) but not clearly different vs. placebo. Plasma volume reduction was small to moderate with Mizone Rapid, PowerAde, and Gatorade relative to placebo (-1.9%, -2.5%, -2.9%; ± 2.5%). Gut comfort was highest with Mizone Rapid but clearly different (8.4% ± 4.8%) only vs PowerAde. Peak power was highest with Mizone Rapid (380 W) vs. placebo and other drinks (1.2-3.0%; 99% confidence limits ±4.7%), but differences were inconclusive with reference to the smallest important effect (~1.2%). The outcomes are consistent with fastest fluid absorption with the hypotonic sports drink. Further research should determine whether the effect has a meaningful impact on performance.

  8. Moderate-Load Muscular Endurance Strength Training Did Not Improve Peak Power or Functional Capacity in Older Men and Women.

    PubMed

    Walker, Simon; Haff, Guy G; Häkkinen, Keijo; Newton, Robert U

    2017-01-01

    The present study determined the effects of muscular endurance strength training on maximum strength and power, functional capacity, muscle activation and hypertrophy in older men and women. Eighty-one men and women acted as an intervention group while 22 acted as non-training controls (age range 64-75 y). Intervention training included super-sets (i.e., paired exercises, immediately performing the second exercises following completion of the first) with short rest intervals (30-60 s between sets) at an intensity of 50-60% one-repetition maximum (1-RM) for 15-20 repetitions. Concentric leg press actions measured maximum strength (1-RM) and concentric peak power. Functional capacity was assessed by maximum speed walking tests (i.e., forward walk, backward walk, timed-up-and-go, and stair climb tests). Quadriceps muscle activation was assessed by surface electromyogram and twitch interpolation technique. Vastus lateralis cross-sectional area was measured by panoramic ultrasound. Compared to control, the intervention groups increased maximum strength (1-RM; men: 10 ± 7% vs. 2 ± 3%, women: 14 ± 9% vs. 1 ± 6% both P < 0.01) and vastus lateralis cross-sectional area (men: 6 ± 7% vs. -3 ± 6%, women: 10 ± 10% vs. 0 ± 4% both P < 0.05). But there were no between-group differences in peak power, muscle activation or functional capacity (e.g., stair climb; men: -5 ± 7% vs. -4 ± 3%, women: -5 ± 6% vs. -2 ± 5% both P > 0.05). While benefits occurred during muscular endurance strength training, specific stimuli are probably needed to target all aspects of age-related health.

  9. Fast ignition integrated experiments and high-gain point design

    SciTech Connect

    Shiraga, H.; Nagatomo, H.; Theobald, W.; Solodov, A. A.; Tabak, M.

    2014-04-17

    Here, integrated fast ignition experiments were performed at ILE, Osaka, and LLE, Rochester, in which a nanosecond driver laser implodes a deuterated plastic shell in front of the tip of a hollow metal cone and an intense ultrashort-pulse laser is injected through the cone to heat the compressed plasma. Based on the initial successful results of fast electron heating of cone-in-shell targets, large-energy short-pulse laser beam lines were constructed and became operational: OMEGA-EP at Rochester and LFEX at Osaka. Neutron enhancement due to heating with a ~kJ short-pulse laser has been demonstrated in the integrated experiments at Osaka and Rochester. The neutron yields are being analyzed by comparing the experimental results with simulations. Details of the fast electron beam transport and the electron energy deposition in the imploded fuel plasma are complicated and further studies are imperative. The hydrodynamics of the implosion was studied including the interaction of the imploded core plasma with the cone tip. Theory and simulation studies are presented on the hydrodynamics of a high-gain target for a fast ignition point design.

  10. 4D fast tracking for experiments at high luminosity LHC

    NASA Astrophysics Data System (ADS)

    Neri, N.; Cardini, A.; Calabrese, R.; Fiorini, M.; Luppi, E.; Marconi, U.; Petruzzo, M.

    2016-11-01

    The full exploitation of the physics potential of the high luminosity LHC is a big challenge that requires new instrumentation and innovative solutions. We present here a conceptual design and simulation studies of a fast timing pixel detector with embedded real-time tracking capabilities. The system is conceived to operate at 40 MHz event rate and to reconstruct tracks in real-time, using precise space and time 4D information of the hit, for fast trigger decisions. This work is part of an R&D project aimed at building an innovative tracking detector with superior time (10 ps) and position (10 μm) resolutions to be used in very harsh radiation environments, for the ultimate flavour physics experiment at the high luminosity phase of the LHC.

  11. High Harmonic Fast Wave Heating and Current Drive for NSTX

    NASA Astrophysics Data System (ADS)

    Robinson, J. A.; Majeski, R.; Menard, J.; Ono, M.; Phillips, C. K.; Wilson, J. R.; Batchelor, D. B.; Carter, M. D.; Jaeger, E. F.; Smithe, D.

    1996-11-01

    Heating and noninductive current drive in NSTX will initially be accomplished with 6 MW of radio-frequency (rf) power applied in the high harmonic fast wave (HHFW) regime. HHFW heating and current drive differs from conventional fast wave current drive in that, although the frequency of operation (30-40 MHz) is in the range of conventional tokamak experiments, ω_rf ~ 10-20 Ω_ci due to the low magnetic field (0.35 T). Strong absorption (100% per pass) is ensured by the high plasma beta. Here we present numerical modelling of HHFW heating and current drive in NSTX using the PICES, FISIC, and METS95 codes. Preliminary designs for the NSTX HHFW antenna and matching system are also presented, along with analysis of the launched antenna wavenumber spectrum using the RANT3D code.

  12. Diamond detector for high rate monitors of fast neutrons beams

    SciTech Connect

    Giacomelli, L.; Rebai, M.; Cippo, E. Perelli; Tardocchi, M.; Fazzi, A.; Andreani, C.; Pietropaolo, A.; Frost, C. D.; Rhodes, N.; Schooneveld, E.; Gorini, G.

    2012-06-19

    A fast neutron detection system suitable for high rate measurements is presented. The detector is based on a commercial high purity single crystal diamond (SDD) coupled to a fast digital data acquisition system. The detector was tested at the ISIS pulsed spallation neutron source. The SDD event signal was digitized at 1 GHz to reconstruct the deposited energy (pulse amplitude) and neutron arrival time; the event time of flight (ToF) was obtained relative to the recorded proton beam signal t{sub 0}. Fast acquisition is needed since the peak count rate is very high ({approx}800 kHz) due to the pulsed structure of the neutron beam. Measurements at ISIS indicate that three characteristics regions exist in the biparametric spectrum: i) background gamma events of low pulse amplitudes; ii) low pulse amplitude neutron events in the energy range E{sub dep}= 1.5-7 MeV ascribed to neutron elastic scattering on {sup 12}C; iii) large pulse amplitude neutron events with E{sub n} < 7 MeV ascribed to {sup 12}C(n,{alpha}){sup 9}Be and 12C(n,n')3{alpha}.

  13. Fast IMRT with narrow high energy scanned photon beams.

    PubMed

    Andreassen, Björn; Strååt, Sara Janek; Holmberg, Rickard; Näfstadius, Peder; Brahme, Anders

    2011-08-01

    Since the first publications on intensity modulated radiation therapy (IMRT) in the early 1980s almost all efforts have been focused on fairly time consuming dynamic or segmental multileaf collimation. With narrow fast scanned photon beams, the flexibility and accuracy in beam shaping increases, not least in combination with fast penumbra trimming multileaf collimators. Previously, experiments have been performed with full range targets, generating a broad bremsstrahlung beam, in combination with multileaf collimators or material compensators. In the present publication, the first measurements with fast narrow high energy (50 MV) scanned photon beams are presented indicating an interesting performance increase even though some of the hardware used were suboptimal. Inverse therapy planning was used to calculate optimal scanning patterns to generate dose distributions with interesting properties for fast IMRT. To fully utilize the dose distributional advantages with scanned beams, it is necessary to use narrow high energy beams from a thin bremsstrahlung target and a powerful purging magnet capable of deflecting the transmitted electron beam away from the generated photons onto a dedicated electron collector. During the present measurements the scanning system, purging magnet, and electron collimator in the treatment head of the MM50 racetrack accelerator was used with 3-6 mm thick bremsstrahlung targets of beryllium. The dose distributions were measured with diodes in water and with EDR2 film in PMMA. Monte Carlo simulations with GEANT4 were used to study the influence of the electrons transmitted through the target on the photon pencil beam kernel. The full width at half-maximum (FWHM) of the scanned photon beam was 34 mm measured at isocenter, below 9.5 cm of water, 1 m from the 3 mm Be bremsstrahlung target. To generate a homogeneous dose distribution in a 10 x 10 cm2 field, the authors used a spot matrix of 100 equal intensity beam spots resulting in a

  14. Study on a fast loading high vacuum multilayer insulation (MLI)

    NASA Astrophysics Data System (ADS)

    Shen, Xian; Zhang, Sheng; Wang, Bo; Gan, Zhihu; Ying, Jianming; Zhang, Chunlin

    2014-01-01

    With the continuous development of vacuum technology, the proportion of high vacuum multilayer insulation method in all kinds of insulation methods is growing [1]. For large cryogenic tanks, the multilayer insulation traditional layer by layer winding way is very inconvenient and takes a lot of time. Different layer density of the multilayer insulation material leads to different thermal insulation performance [2]. Because of the influence of man-made factors, the traditional way of winding is difficult to achieve a consistent density. This paper compared the fast loading type insulation and traditional insulation in a different degree of vacuum, it can be seen that the apparent thermal conductivity of these two types is similar. But fast loading multilayer insulation material is more convenient on the installation and it can eliminate the man-made factors. So it has practical value in engineering applications.

  15. High Bandwidth Short Stroke Rotary Fast Tool Servo

    SciTech Connect

    Montesanti, R C; Trumper, D L

    2003-08-22

    This paper presents the design and performance of a new rotary fast tool servo (FTS) capable of developing the 40 g's tool tip acceleration required to follow a 5 micron PV sinusoidal surface at 2 kHz with a planned accuracy of 50 nm, and having a full stroke of 50 micron PV at lower frequencies. Tests with de-rated power supplies have demonstrated a closed-loop unity-gain bandwidth of 2 kHz with 20 g's tool acceleration, and we expect to achieve 40 g's with supplies providing {+-} 16 Amp to the Lorentz force actuator. The use of a fast tool servo with a diamond turning machine for producing non-axisymmetric or textured surfaces on a workpiece is well known. Our new rotary FTS was designed to specifically accommodate fabricating prescription textured surfaces on 5 mm diameter spherical target components for High Energy Density Physics experiments on the National Ignition Facility Laser (NIF).

  16. The axial topographic high at intermediate and fast spreading ridges

    NASA Astrophysics Data System (ADS)

    Carbotte, Suzanne M.; MacDonald, Ken C.

    1994-12-01

    An axial topographic high is commonly observed at both fast spreading ridges and some segments of intermediate spreading ridges. At fast rates the axial high is primarily created by the buoyancy of hot rock and magma beneath the rise. As newly formed crust is transported off axis, little vestige of an axial high is observed on the ridge flanks. In contrast, at intermediate rates, a significant component of the positive topography may be a volcanic construction, preserved on the ridge flanks as abyssal hills, which are slit axial volcanoes. We suggest this difference in the nature of the axial high reflects a lithosphere strong enough to support construction of a volcanic crestal ridge at intermediate spreading rates, but only rarely at fast rates. Relict overlap ridges, found within the discordant zones left by overlapping spreading centers, is one class of ridge-flank topography which appears to have a significant volcanic constructional component even at fast spreading ridges. Unlike topography away from these discontinuities, the relief and shape of overlapping spreading centers is preserved as relict ridge tips are rafted onto the ridge flanks. Reduced magma supply at these discontinuities may give rise to an axial lithosphere strong enough to support volcanic construction of overlap ridges. Low axial lithospheric strength may also account for the lack of normal faults within the innermost 1-2 km of fast, and some intermediate, spreading ridges. With a thin/weak brittle layer at the ridge crest, tensile failure will predominate and few normal faults will form. Depths to the axial magma chamber reflector observed in multi-channel seismic data limit the thickness of the brittel layer on axis to less than 1-2 km for much of the East Pacific Rise (EPR). This depth is comparable to depths over which tensile failure within the oceanic crust will predominate, estimated from the Griffith criteria for fracture initiation (approx. 0.5-1.5 km). As the brittle layer

  17. Fast ion absorption of the high harmonic fast wave in the National Spherical Torus Experiment

    NASA Astrophysics Data System (ADS)

    Rosenberg, A. L.; Menard, J. E.; Wilson, J. R.; Medley, S. S.; Andre, R.; Phillips, C. K.; Darrow, D. S.; LeBlanc, B. P.; Redi, M. H.; Fisch, N. J.; NSTX Team, Harvey, R. W.; Mau, T. K.; Jaeger, E. F.; Ryan, P. M.; Swain, D. W.; Sabbagh, S. A.; Egedal, J.

    2004-05-01

    Ion absorption of the high harmonic fast wave in a spherical torus [Y.-K. M. Peng et al., Nucl. Fusion 26, 769 (1986)] is of critical importance to assessing the viability of the wave as a means of heating and driving current. Analysis of recent National Spherical Torus Experiment [M. Ono et al., Nucl. Fusion 40, 557 (2000)] shots has revealed that under some conditions when neutral beam and rf power are injected into the plasma simultaneously, a fast ion population with energy above the beam injection energy is sustained by the wave. In agreement with modeling, these experiments find the rf-induced fast ion tail strength and neutron rate at lower B-fields to be less enhanced, likely due to a larger β profile, which promotes greater off-axis absorption where the fast ion population is small. Ion loss codes find the increased loss fraction with decreased B insufficient to account for the changes in tail strength, providing further evidence that this is a rf interaction effect. Though greater ion absorption is predicted with lower k∥, surprisingly little variation in the tail was observed, along with a neutron rate enhancement with higher k∥. Data from the neutral particle analyzer, neutron detectors, x-ray crystal spectrometer, and Thomson scattering are presented, along with results from the TRANSP [R. J. Hawryluk, Physics of Plasmas Close to Thermonuclear Conditions 1, 19 (1981); J. P. H. E. Ongena et al., Fusion Technol. 33, 181 (1998)] transport analysis code, ray-tracing codes HPRT [J. Menard et al., Phys. Plasmas 6, 2002 (1999)], and CURRAY [T. K. Mau et al., RF Power in Plasmas: 13th Topical Conference (1999), p. 148], full-wave code AORSA [E. F. Jaeger et al., RF Power in Plasmas: 14th Topical Conference, 2001, p. 369], quasilinear code CQL3D [R. W. Harvey et al., in Proceedings of the IAEA TCM on Advances in Simulation and Modeling of Thermonuclear Plasmas, 1992], and ion loss codes EIGOL [D. S. Darrow et al., in Proceedings of the 6th IAEA TCM on

  18. Fast recovery, high voltage silicon diodes for AC motor controllers

    NASA Technical Reports Server (NTRS)

    Balodis, V.; Berman, A. H.; Gaugh, C.

    1982-01-01

    The fabrication and characterization of a high voltage, high current, fast recovery silicon diode for use in AC motor controllers, originally developed for NASA for use in avionics power supplies, is presented. The diode utilizes a positive bevel PIN mesa structure with glass passivation and has the following characteristics: peak inverse voltage - 1200 volts, forward voltage at 50 amperes - 1.5 volts, reverse recovery time of 200 nanoseconds. Characterization data for the diode, included in a table, show agreement with design concepts developed for power diodes. Circuit diagrams of the diode are also given.

  19. Reproducibility of Outdoor Flat and Uphill Cycling Time Trials and Their Performance Correlates with Peak Power Output in Moderately Trained Cyclists

    PubMed Central

    Tan, Frankie H. Y.; Aziz, Abdul Rashid

    2005-01-01

    The aims of the present study were firstly to examine the reproducibility of outdoor flat and uphill cycling time trials (TT), and secondly to assess the relationship between peak power output (Wpeak) obtained in the laboratory and outdoor cycling performance in moderately trained cyclists. Eight competitive male cyclists first performed a progressive cycle ergometer test in the laboratory to determine Wpeak (W). Thereafter, they performed three 36 km TT (TT36) on a flat course on separate days and at the same time of the day. On a different day, they also performed three 1.4 km uphill TT (TT1.4) in a single day. The coefficient of variation (CV) values across three TT36 and TT1.4 ranged from 1.1 - 1.4% and 2.6 - 2.9%, for performance time (min) and mean power (W), respectively. The correlation between absolute Wpeak (W) obtained in the laboratory and mean power during TT36 and TT1.4 was 0.90 (p < 0.01) and 0.98 (p < 0.01), respectively. Absolute Wpeak (W) correlated significantly with performance time in TT36 (r = -0.72, p < 0.05) but not in TT1.4 (r = -0.52, p > 0.05). The correlation between relative Wpeak (W·kg-1) and performance time in TT36 and TT1.4 was r = -0.65 (p > 0.05) and r = -0.91 (p < 0.01), respectively. In conclusion, under stable environmental conditions, performance time and mean power are highly reproducible in moderately trained cyclists during outdoor cycling TT. Laboratory determined absolute Wpeak (W) may predict cycling performance on a flat course but relative Wpeak (W·kg-1) is a better predictor of performance during uphill cycling. Key Points Under stable environmental conditions, performance time and mean power are highly reproducible in moderately trained cyclists during outdoor flat and uphill cycling time trials. Laboratory determined peak power output (Wpeak) (W) may predict cycling performance on a flat course. Laboratory determined relative Wpeak (W·kg-1) is a better predictor of performance during uphill cycling PMID:24453532

  20. Reproducibility of outdoor flat and uphill cycling time trials and their performance correlates with peak power output in moderately trained cyclists.

    PubMed

    Tan, Frankie H Y; Aziz, Abdul Rashid

    2005-09-01

    The aims of the present study were firstly to examine the reproducibility of outdoor flat and uphill cycling time trials (TT), and secondly to assess the relationship between peak power output (Wpeak) obtained in the laboratory and outdoor cycling performance in moderately trained cyclists. Eight competitive male cyclists first performed a progressive cycle ergometer test in the laboratory to determine Wpeak (W). Thereafter, they performed three 36 km TT (TT36) on a flat course on separate days and at the same time of the day. On a different day, they also performed three 1.4 km uphill TT (TT1.4) in a single day. The coefficient of variation (CV) values across three TT36 and TT1.4 ranged from 1.1 - 1.4% and 2.6 - 2.9%, for performance time (min) and mean power (W), respectively. The correlation between absolute Wpeak (W) obtained in the laboratory and mean power during TT36 and TT1.4 was 0.90 (p < 0.01) and 0.98 (p < 0.01), respectively. Absolute Wpeak (W) correlated significantly with performance time in TT36 (r = -0.72, p < 0.05) but not in TT1.4 (r = -0.52, p > 0.05). The correlation between relative Wpeak (W·kg(-1)) and performance time in TT36 and TT1.4 was r = -0.65 (p > 0.05) and r = -0.91 (p < 0.01), respectively. In conclusion, under stable environmental conditions, performance time and mean power are highly reproducible in moderately trained cyclists during outdoor cycling TT. Laboratory determined absolute Wpeak (W) may predict cycling performance on a flat course but relative Wpeak (W·kg(-1)) is a better predictor of performance during uphill cycling. Key PointsUnder stable environmental conditions, performance time and mean power are highly reproducible in moderately trained cyclists during outdoor flat and uphill cycling time trials.Laboratory determined peak power output (Wpeak) (W) may predict cycling performance on a flat course.Laboratory determined relative Wpeak (W·kg(-1)) is a better predictor of performance during uphill cycling.

  1. Liquid Nitrogen as Fast High Voltage Switching Medium

    NASA Astrophysics Data System (ADS)

    Dickens, J.; Neuber, A.; Haustein, M.; Krile, J.; Krompholz, H.

    2002-12-01

    Compact pulsed power systems require new switching technologies. For high voltages, liquid nitrogen seems to be a suitable switching medium, with high hold-off voltage, low dielectric constant, and no need for pressurized systems as in high pressure gas switches. The discharge behavior in liquid nitrogen, such as breakdown voltages, formative times, current rise as function of voltage, recovery, etc. are virtually unknown, however. The phenomenology of breakdown in liquid nitrogen is investigated with high speed (temporal resolution < 1 ns) electrical and optical diagnostics, in a coaxial system with 50-Ohm impedance. Discharge current and voltage are determined with transmission line type current sensors and capacitive voltage dividers. The discharge luminosity is measured with photomultiplier tubes. Preliminary results of self-breakdown investigations (gap 1 mm, breakdown voltage 44 kV, non-boiling supercooled nitrogen) show a fast (2 ns) transition from an unknown current level to several mA, a long-duration (100 ns) phase with constant current superimposed by ns-spikes, and a final fast transition to the impedance limited current during several nanoseconds. The optical measurements will be expanded toward spectroscopy and high speed photography with the aim of clarifying the overall breakdown mechanisms, including electronic initiation, bubble formation, bubble dynamics, and their role in breakdown, for different electrode geometries (different macroscopic field enhancements).

  2. Fast high-temperature superconductor switch for high current applications

    SciTech Connect

    Solovyov, VF; Li, Q

    2013-07-15

    Reversible operation of a high current superconductor switch based on the quench of high-resistance second generation high temperature superconducting wire is demonstrated. The quench is induced by a burst of an ac field generated by an inductively coupled radio-frequency coil. The switch makes a superconducting-to-normal transition within 5 ms and also has a rapid recovery to the superconducting state. The device has potential applications as an active current limiter or as a storage switch for superconducting magnetic energy storage systems. Operation in a full flux penetration/flow regime can effectively minimize the detrimental effects of the intrinsic conductor non-uniformity. (C) 2013 AIP Publishing LLC.

  3. Solid-state repetitive generator with a gyromagnetic nonlinear transmission line operating as a peak power amplifier

    NASA Astrophysics Data System (ADS)

    Gusev, A. I.; Pedos, M. S.; Rukin, S. N.; Timoshenkov, S. P.

    2017-07-01

    In this work, experiments were made in which gyromagnetic nonlinear transmission line (NLTL) operates as a peak power amplifier of the input pulse. At such an operating regime, the duration of the input pulse is close to the period of generated oscillations, and the main part of the input pulse energy is transmitted only to the first peak of the oscillations. Power amplification is achieved due to the voltage amplitude of the first peak across the NLTL output exceeding the voltage amplitude of the input pulse. In the experiments, the input pulse with an amplitude of 500 kV and a half-height pulse duration of 7 ns is applied to the NLTL with a natural oscillation frequency of ˜300 MHz. At the output of the NLTL in 40 Ω coaxial transmission line, the pulse amplitude is increased to 740 kV and the pulse duration is reduced to ˜2 ns, which correspond to power amplification of the input pulse from ˜6 to ˜13 GW. As a source of input pulses, a solid-state semiconductor opening switch generator was used, which allowed carrying out experiments at pulse repetition frequency up to 1 kHz in the burst mode of operation.

  4. Relationships among peak power output, peak bar velocity, and mechanomyographic amplitude during the free-weight bench press exercise.

    PubMed

    Stock, Matt S; Beck, Travis W; Defreitas, Jason M; Dillon, Michael A

    2010-10-01

    The purpose of this study was to examine the relationships among mechanomyographic (MMG) amplitude, power output, and bar velocity during the free-weight bench press exercise. Twenty-one resistance-trained men [one-repetition maximum (1-RM) bench press = 125.4+18.4 kg] performed bench press muscle actions as explosively as possible from 10% to 90% of the 1-RM while peak power output and peak bar velocity were assessed with a TENDO Weightlifting Analyzer. During each muscle action, surface MMG signals were detected from the right and left pectoralis major and triceps brachii, and the concentric portion of the range of motion was selected for analysis. Results indicated that power output increased from 10% to 50% 1-RM, followed by decreases from 50% to 90% 1-RM, but MMG amplitude for each of the muscles increased from 10 to 80% 1-RM. The results of this study indicate that during the free-weight bench press exercise, MMG amplitude was not related to power output, but was inversely related to bar velocity and directly related to the external load being lifted. In future research, coaches and sport scientists may be able to estimate force/torque production from individual muscles during multi-joint, dynamic constant external resistance muscle actions.

  5. High pressure phase transformation in iron under fast compression

    SciTech Connect

    Bastea, M; Bastea, S; Becker, R

    2009-07-07

    We present experimental results on the solid-solid, {alpha} to {epsilon} phase transformation kinetics of iron under high pressure dynamic compression. We observe kinetic features - velocity loops - similar with the ones recently reported to occur when water is frozen into its ice VII phase under comparable experimental conditions. We analyze this behavior in terms of general ideas coupling the steady sample compression with phase nucleation and growth with a pressure dependent phase interface velocity. The model is used to predict the response of iron when steadily driven across the {alpha} - {epsilon} phase boundary on very short time scales, including those envisioned to be achieved in ultra-fast laser experiments.

  6. A fast directional algorithm for high-frequency electromagnetic scattering

    SciTech Connect

    Tsuji, Paul; Ying Lexing

    2011-06-20

    This paper is concerned with the fast solution of high-frequency electromagnetic scattering problems using the boundary integral formulation. We extend the O(N log N) directional multilevel algorithm previously proposed for the acoustic scattering case to the vector electromagnetic case. We also detail how to incorporate the curl operator of the magnetic field integral equation into the algorithm. When combined with a standard iterative method, this results in an almost linear complexity solver for the combined field integral equations. In addition, the butterfly algorithm is utilized to compute the far field pattern and radar cross section with O(N log N) complexity.

  7. High-contrast and fast electrochromic switching enabled by plasmonics

    PubMed Central

    Xu, Ting; Walter, Erich C.; Agrawal, Amit; Bohn, Christopher; Velmurugan, Jeyavel; Zhu, Wenqi; Lezec, Henri J.; Talin, A. Alec

    2016-01-01

    With vibrant colours and simple, room-temperature processing methods, electrochromic polymers have attracted attention as active materials for flexible, low-power-consuming devices. However, slow switching speeds in devices realized to date, as well as the complexity of having to combine several distinct polymers to achieve a full-colour gamut, have limited electrochromic materials to niche applications. Here we achieve fast, high-contrast electrochromic switching by significantly enhancing the interaction of light—propagating as deep-subwavelength-confined surface plasmon polaritons through arrays of metallic nanoslits, with an electrochromic polymer—present as an ultra-thin coating on the slit sidewalls. The switchable configuration retains the short temporal charge-diffusion characteristics of thin electrochromic films, while maintaining the high optical contrast associated with thicker electrochromic coatings. We further demonstrate that by controlling the pitch of the nanoslit arrays, it is possible to achieve a full-colour response with high contrast and fast switching speeds, while relying on just one electrochromic polymer. PMID:26814453

  8. High-contrast and fast electrochromic switching enabled by plasmonics

    DOE PAGES

    Xu, Ting; Walter, Erich C.; Agrawal, Amit; ...

    2016-01-27

    With vibrant colours and simple, room-temperature processing methods, electrochromic polymers have attracted attention as active materials for flexible, low-power-consuming devices. However, slow switching speeds in devices realized to date, as well as the complexity of having to combine several distinct polymers to achieve a full-colour gamut, have limited electrochromic materials to niche applications. Here we achieve fast, high-contrast electrochromic switching by significantly enhancing the interaction of light—propagating as deep-subwavelength-confined surface plasmon polaritons through arrays of metallic nanoslits, with an electrochromic polymer—present as an ultra-thin coating on the slit sidewalls. The switchable configuration retains the short temporal charge-diffusion characteristics of thinmore » electrochromic films, while maintaining the high optical contrast associated with thicker electrochromic coatings. In conclusion, we further demonstrate that by controlling the pitch of the nanoslit arrays, it is possible to achieve a full-colour response with high contrast and fast switching speeds, while relying on just one electrochromic polymer.« less

  9. High-contrast and fast electrochromic switching enabled by plasmonics

    SciTech Connect

    Xu, Ting; Walter, Erich C.; Agrawal, Amit; Bohn, Christopher; Velmurugan, Jeyavel; Zhu, Wenqi; Lezec, Henri J.; Talin, A. Alec

    2016-01-27

    With vibrant colours and simple, room-temperature processing methods, electrochromic polymers have attracted attention as active materials for flexible, low-power-consuming devices. However, slow switching speeds in devices realized to date, as well as the complexity of having to combine several distinct polymers to achieve a full-colour gamut, have limited electrochromic materials to niche applications. Here we achieve fast, high-contrast electrochromic switching by significantly enhancing the interaction of light—propagating as deep-subwavelength-confined surface plasmon polaritons through arrays of metallic nanoslits, with an electrochromic polymer—present as an ultra-thin coating on the slit sidewalls. The switchable configuration retains the short temporal charge-diffusion characteristics of thin electrochromic films, while maintaining the high optical contrast associated with thicker electrochromic coatings. In conclusion, we further demonstrate that by controlling the pitch of the nanoslit arrays, it is possible to achieve a full-colour response with high contrast and fast switching speeds, while relying on just one electrochromic polymer.

  10. High-contrast and fast electrochromic switching enabled by plasmonics

    NASA Astrophysics Data System (ADS)

    Talin, Albert; Xu, Ting; Walter, Erich; Agrawal, Amit; Bohn, Christopher; Velmurugan, Jeyavel; Zhu, Wenqi; Lezec, Henri

    With vibrant colors and simple, room-temperature processing methods, electrochromic polymers have long attracted attention as active materials for flexible, low-power consuming devices such as smart windows and displays. However, despite their many advantages, slow switching speed and complexity of combining several separate polymers to achieve full-color gamut has limited electrochromic materials to niche applications. Here we exploit the enhanced light-matter interaction associated with the deep-subwavelength mode confinement of surface plasmon polaritons propagating in metallic nanoslit arrays coated with ultra-thin electrochromic polymers to build a novel configuration for achieving high-contrast and fast electrochromic switching. The switchable configuration retains the short temporal charge-diffusion characteristics of thin electrochromic films while maintaining the high optical-contrast associated with thicker electrochromic coatings. We further demonstrate that by controlling the pitch of the nanoslit arrays, it is possible to achieve a full-color response with high-contrast and fast switching-speeds while relying on just one electrochromic polymer.

  11. High-contrast and fast electrochromic switching enabled by plasmonics

    NASA Astrophysics Data System (ADS)

    Xu, Ting; Walter, Erich C.; Agrawal, Amit; Bohn, Christopher; Velmurugan, Jeyavel; Zhu, Wenqi; Lezec, Henri J.; Talin, A. Alec

    2016-01-01

    With vibrant colours and simple, room-temperature processing methods, electrochromic polymers have attracted attention as active materials for flexible, low-power-consuming devices. However, slow switching speeds in devices realized to date, as well as the complexity of having to combine several distinct polymers to achieve a full-colour gamut, have limited electrochromic materials to niche applications. Here we achieve fast, high-contrast electrochromic switching by significantly enhancing the interaction of light--propagating as deep-subwavelength-confined surface plasmon polaritons through arrays of metallic nanoslits, with an electrochromic polymer--present as an ultra-thin coating on the slit sidewalls. The switchable configuration retains the short temporal charge-diffusion characteristics of thin electrochromic films, while maintaining the high optical contrast associated with thicker electrochromic coatings. We further demonstrate that by controlling the pitch of the nanoslit arrays, it is possible to achieve a full-colour response with high contrast and fast switching speeds, while relying on just one electrochromic polymer.

  12. High-contrast and fast electrochromic switching enabled by plasmonics.

    PubMed

    Xu, Ting; Walter, Erich C; Agrawal, Amit; Bohn, Christopher; Velmurugan, Jeyavel; Zhu, Wenqi; Lezec, Henri J; Talin, A Alec

    2016-01-27

    With vibrant colours and simple, room-temperature processing methods, electrochromic polymers have attracted attention as active materials for flexible, low-power-consuming devices. However, slow switching speeds in devices realized to date, as well as the complexity of having to combine several distinct polymers to achieve a full-colour gamut, have limited electrochromic materials to niche applications. Here we achieve fast, high-contrast electrochromic switching by significantly enhancing the interaction of light--propagating as deep-subwavelength-confined surface plasmon polaritons through arrays of metallic nanoslits, with an electrochromic polymer--present as an ultra-thin coating on the slit sidewalls. The switchable configuration retains the short temporal charge-diffusion characteristics of thin electrochromic films, while maintaining the high optical contrast associated with thicker electrochromic coatings. We further demonstrate that by controlling the pitch of the nanoslit arrays, it is possible to achieve a full-colour response with high contrast and fast switching speeds, while relying on just one electrochromic polymer.

  13. Fast High Capacity Annular Gas Puff Valve Design Concept

    NASA Astrophysics Data System (ADS)

    Ruden, Edward

    2000-10-01

    A fast opening gas valve design concept is presented that can theoretically inject a few grams of D2 gas radially outward into a coaxial annular vacuum region with a radius of about 10 cm in less that 100 μ s. The concept employs a single turn 20-30 T pulsed magnetic field coil that axially accelerates an Mg alloy ring, which seals a gas plenum, to high velocity, releasing the gas. Both coil and ring are profiled to minimize stress in the ring. Such a device could be used to supply the initial gas load for a proposed 5 MJ Dense Plasma Focus driven by AFRL's Shiva Star Capacitor bank. The intent here is keep the vacuum current feed insulator under high vacuum during the discharge to avoid surface breakdown. Alternatively, a high energy rep ratable plasma flow opening switch could be supplied with such a valve. This work is funded by the USAF.

  14. Controllable high voltage source having fast settling time

    NASA Technical Reports Server (NTRS)

    Doong, H.; Acuna, M. H. (Inventor)

    1975-01-01

    A high voltage dc stepping power supply for sampling a utilization device such as an electrostatic analyzer has a relatively fast settling time for voltage steps. The supply includes a waveform generator for deriving a low voltage staircase waveform that feeds a relatively long response time power supply, deriving a high output voltage generally equal to a predetermined multiple of the input voltage. In the power supply, an ac voltage modulated by the staircase waveform is applied to a step-up transformer and then to a voltage multiplier stack to form a high voltage, relatively poor replica of the input waveform at an intermediate output terminal. A constant dc source, applied to the input of the power supply, biases the voltage at the intermediate output terminal to be in excess of the predetermined multiple of the input voltage.

  15. High Harmonic Fast Wave heating and current drive for NSTX

    NASA Astrophysics Data System (ADS)

    Robinson, J. A.; Majeski, R.; Hosea, J.; Menard, J.; Ono, M.; Phillips, C. K.; Wilson, J. R.; Wright, J.; Batchelor, D. B.; Carter, M. D.; Jaeger, E. F.; Ryan, P.; Swain, D.; Mau, T. K.; Chiu, S. C.; Smithe, D.

    1997-11-01

    Heating and noninductive current drive in NSTX will initially use 6 MW of rf power in the high harmonic fast wave (HHFW) regime. We present numerical modelling of HHFW heating and current drive in NSTX using the PICES, CURRAY, FISIC, and METS95 codes. High electron β during the discharge flattop in NSTX is predicted to result in off-axis power deposition and current drive. However, reductions in the trapped electron fraction (due also to high β effects) are predicted to result in adequate current drive efficiency, with ~ 400 - 500 kA of noninductive current driven. Sufficient per-pass absorption (>10%) to ensure effective electron heating is also expected for the startup plasma. Present plans call for a single twelve strap antenna driven by six FMIT transmitters operating at 30 MHz. The design for the antenna and matching system will also be discussed.

  16. High peak-power passively Q-switched all-ceramics Nd:YAG/Cr4+:YAG lasers

    NASA Astrophysics Data System (ADS)

    Pavel, Nicolaie; Tsunekane, Masaki; Taira, Takunori

    2010-05-01

    The output performances of a compact, passively Q-switched Nd:YAG/Cr4+:YAG laser were investigated using single crystals and poli-crystalline ceramics Nd:YAG with doping level between 1.0 and 2.0-at.% Nd, and single crystals and poli-crystalline ceramics Cr4+:YAG with various initial transmission. Q-switch laser pulses at 1.06 μm with energies up to 2 mJ and duration below 1 ns were realized at a pump repetition rate of 10 Hz. An all-ceramics Nd:YAG/Cr4+:YAG laser could be a solution for ignition of automotive engines. The optical intensity of a laser pulse with ns duration that induces optical air breakdown was determined.

  17. High peak-power passively Q-switched all-ceramics Nd:YAG/Cr4+:YAG lasers

    NASA Astrophysics Data System (ADS)

    Pavel, Nicolaie; Tsunekane, Masaki; Taira, Takunori

    2009-09-01

    The output performances of a compact, passively Q-switched Nd:YAG/Cr4+:YAG laser were investigated using single crystals and poli-crystalline ceramics Nd:YAG with doping level between 1.0 and 2.0-at.% Nd, and single crystals and poli-crystalline ceramics Cr4+:YAG with various initial transmission. Q-switch laser pulses at 1.06 μm with energies up to 2 mJ and duration below 1 ns were realized at a pump repetition rate of 10 Hz. An all-ceramics Nd:YAG/Cr4+:YAG laser could be a solution for ignition of automotive engines. The optical intensity of a laser pulse with ns duration that induces optical air breakdown was determined.

  18. No Effects of High-Peak-Power Microwave Pulses at 2.36 GHz on Behavioral Performance in Monkeys.

    DTIC Science & Technology

    1990-06-01

    a film badge for cumulative exposure across all sessions, as well as another film badge to measure skin-dose x-ray exposure during a single session . The...cumulative exposure dosimetry range was 122-290 mR; the range for single - session exposures was 41-53 mR. The skin dose of x rays received by the

  19. High-resolution wide-band fast Fourier transform spectrometers

    NASA Astrophysics Data System (ADS)

    Klein, B.; Hochgürtel, S.; Krämer, I.; Bell, A.; Meyer, K.; Güsten, R.

    2012-06-01

    We describe the performance of our latest generations of sensitive wide-band high-resolution digital fast Fourier transform spectrometer (FFTS). Their design, optimized for a wide range of radio astronomical applications, is presented. Developed for operation with the GREAT far infrared heterodyne spectrometer on-board SOFIA, the eXtended bandwidth FFTS (XFFTS) offers a high instantaneous bandwidth of 2.5 GHz with 88.5 kHz spectral resolution and has been in routine operation during SOFIA's Basic Science since July 2011. We discuss the advanced field programmable gate array (FPGA) signal processing pipeline, with an optimized multi-tap polyphase filter bank algorithm that provides a nearly loss-less time-to-frequency data conversion with significantly reduced frequency scallop and fast sidelobe fall-off. Our digital spectrometers have been proven to be extremely reliable and robust, even under the harsh environmental conditions of an airborne observatory, with Allan-variance stability times of several 1000 s. An enhancement of the present 2.5 GHz XFFTS will duplicate the number of spectral channels (64k), offering spectroscopy with even better resolution during Cycle 1 observations.

  20. Fast Gibbs sampling for high-dimensional Bayesian inversion

    NASA Astrophysics Data System (ADS)

    Lucka, Felix

    2016-11-01

    Solving ill-posed inverse problems by Bayesian inference has recently attracted considerable attention. Compared to deterministic approaches, the probabilistic representation of the solution by the posterior distribution can be exploited to explore and quantify its uncertainties. In applications where the inverse solution is subject to further analysis procedures can be a significant advantage. Alongside theoretical progress, various new computational techniques allow us to sample very high dimensional posterior distributions: in (Lucka 2012 Inverse Problems 28 125012), and a Markov chain Monte Carlo posterior sampler was developed for linear inverse problems with {{\\ell }}1-type priors. In this article, we extend this single component (SC) Gibbs-type sampler to a wide range of priors used in Bayesian inversion, such as general {{\\ell }}pq priors with additional hard constraints. In addition, a fast computation of the conditional, SC densities in an explicit, parameterized form, a fast, robust and exact sampling from these one-dimensional densities is key to obtain an efficient algorithm. We demonstrate that a generalization of slice sampling can utilize their specific structure for this task and illustrate the performance of the resulting slice-within-Gibbs samplers by different computed examples. These new samplers allow us to perform sample-based Bayesian inference in high-dimensional scenarios with certain priors for the first time, including the inversion of computed tomography data with the popular isotropic total variation prior.

  1. Profiles of fast ions that are accelerated by high harmonic fast waves in the National Spherical Torus Experiment

    NASA Astrophysics Data System (ADS)

    Liu, D.; Heidbrink, W. W.; Podestà, M.; Bell, R. E.; Fredrickson, E. D.; Medley, S. S.; Harvey, R. W.; Ruskov, E.

    2010-02-01

    Combined neutral beam injection and high-harmonic fast-wave (HHFW) heating accelerate deuterium fast ions in the National Spherical Torus Experiment (NSTX). With 1.1 MW of HHFW power, the neutron emission rate is about three times larger than in the comparison discharge without HHFW heating. Acceleration of fast ions above the beam injection energy is evident on an E||B type neutral particle analyzer (NPA), a 4-chord solid state neutral particle analyzer (SSNPA) array and a 16-channel fast-ion D-alpha (FIDA) diagnostic. The accelerated fast ions observed by the NPA and SSNPA diagnostics mainly come from passive charge exchange reactions at the edge due to the NPA/SSNPA localization in phase space. The spatial profile of accelerated fast ions that is measured by the FIDA diagnostic is much broader than in conventional tokamaks because of the multiple resonance layers and large orbits in NSTX. The fast-ion distribution function calculated by the CQL3D Fokker-Planck code differs from the measured spatial profile, presumably because the current version of CQL3D uses a zero-banana-width model. In addition, compressional Alfven eigenmode activity is stronger during the HHFW heating and it may affect the fast-ion spatial profile.

  2. Highly Parallelized Pattern Matching Hardware for Fast Tracking at Hadron Colliders

    NASA Astrophysics Data System (ADS)

    Citraro, S.; Annovi, A.; Biesuz, N.; Giannetti, P.; Luciano, P.; Nasimi, H.; Piendibene, M.; Sotiropoulou, C.-L.; Volpi, G.

    2016-04-01

    A high-performance “pattern matching” implementation based on the Associative Memory (AM) system is presented. It is designed to solve the real-time hit-to-track association problem for particles produced in high-energy physics experiments at hadron colliders. The processing time of pattern recognition in CPU-based algorithms increases rapidly with the detector occupancy due to the limited computing power and input-output capacity of hardware available on the market. The AM system presented here solves the problem by being able to process even the most complex hadron collider events produced at a rate of 100 kHz with an average latency smaller than 10 μs. The board built for this goal is able to execute 12 petabyte comparisons per second, with peak power consumption below 250 W, uniformly distributed on the large area of the board.

  3. High performance infrared fast cooled detectors for missile applications

    NASA Astrophysics Data System (ADS)

    Reibel, Yann; Espuno, Laurent; Taalat, Rachid; Sultan, Ahmad; Cassaigne, Pierre; Matallah, Noura

    2016-05-01

    SOFRADIR was selected in the late 90's for the production of 320×256 MW detectors for major European missile programs. This experience has established our company as a key player in the field of missile programs. SOFRADIR has since developed a vast portfolio of lightweight, compact and high performance JT-based solutions for missiles. ALTAN is a 384x288 Mid Wave infrared detector with 15μm pixel pitch, and is offered in a miniature ultra-fast Joule- Thomson cooled Dewar. Since Sofradir offers both Indium Antimonide (InSb) and Mercury Cadmium Telluride technologies (MCT), we are able to deliver the detectors best suited to customers' needs. In this paper we are discussing different figures of merit for very compact and innovative JT-cooled detectors and are highlighting the challenges for infrared detection technologies.

  4. Fast demographic traits promote high diversification rates of Amazonian trees

    PubMed Central

    Baker, Timothy R; Pennington, R Toby; Magallon, Susana; Gloor, Emanuel; Laurance, William F; Alexiades, Miguel; Alvarez, Esteban; Araujo, Alejandro; Arets, Eric J M M; Aymard, Gerardo; de Oliveira, Atila Alves; Amaral, Iêda; Arroyo, Luzmila; Bonal, Damien; Brienen, Roel J W; Chave, Jerome; Dexter, Kyle G; Di Fiore, Anthony; Eler, Eduardo; Feldpausch, Ted R; Ferreira, Leandro; Lopez-Gonzalez, Gabriela; van der Heijden, Geertje; Higuchi, Niro; Honorio, Eurídice; Huamantupa, Isau; Killeen, Tim J; Laurance, Susan; Leaño, Claudio; Lewis, Simon L; Malhi, Yadvinder; Marimon, Beatriz Schwantes; Marimon Junior, Ben Hur; Monteagudo Mendoza, Abel; Neill, David; Peñuela-Mora, Maria Cristina; Pitman, Nigel; Prieto, Adriana; Quesada, Carlos A; Ramírez, Fredy; Ramírez Angulo, Hirma; Rudas, Agustin; Ruschel, Ademir R; Salomão, Rafael P; de Andrade, Ana Segalin; Silva, J Natalino M; Silveira, Marcos; Simon, Marcelo F; Spironello, Wilson; ter Steege, Hans; Terborgh, John; Toledo, Marisol; Torres-Lezama, Armando; Vasquez, Rodolfo; Vieira, Ima Célia Guimarães; Vilanova, Emilio; Vos, Vincent A; Phillips, Oliver L; Wiens, John

    2014-01-01

    The Amazon rain forest sustains the world's highest tree diversity, but it remains unclear why some clades of trees are hyperdiverse, whereas others are not. Using dated phylogenies, estimates of current species richness and trait and demographic data from a large network of forest plots, we show that fast demographic traits – short turnover times – are associated with high diversification rates across 51 clades of canopy trees. This relationship is robust to assuming that diversification rates are either constant or decline over time, and occurs in a wide range of Neotropical tree lineages. This finding reveals the crucial role of intrinsic, ecological variation among clades for understanding the origin of the remarkable diversity of Amazonian trees and forests. PMID:24589190

  5. Generation of 25-ns pulses with a peak power of over 10 kW from a gain-switched, 2-mm Tm-doped fibre laser and amplifier system

    SciTech Connect

    Swiderski, J; Michalska, M; Pichola, W; Mamajek, M

    2014-04-28

    We report on an all-fibre, gain-switched, Tm{sup 3+}-doped silica fibre laser and amplifier system generating a train of pulses at a wavelength of 1994.4 nm. When operating at a pulse repetition frequency f=''100'' kHz, it delivered the maximum average power as high as 9.03 W with a slope efficiency of 36.4%. At f = 26 kHz, stable 25-ns pulses with an energy of 0.28 mJ corresponding to a peak power of 10.5 kW were obtained. The performance of the laser system is described. (lasers)

  6. Comparison of measurements and simulations of fast ion profiles during high harmonic fast wave heating in NSTX

    NASA Astrophysics Data System (ADS)

    Liu, D.; Heidbrink, W. W.; Podesta, M.; Medley, S. S.; Harvey, R. W.; Choi, M.; Green, D.

    2009-11-01

    Combined neutral beam injection (NBI) and high harmonic fast wave (HHFW) heating at cyclotron harmonics accelerate deuterium fast ions in the National Spherical Torus Experiment (NSTX). Acceleration of fast ions above the beam injection energy is evident in the data from neutron, E||B type Neutral Particle Analyzer (NPA), Solid State Neutral Particle Analyzer (SSNPA) array and Fast-Ion D-Alpha (FIDA) diagnostics. The fast-ion spatial profiles measured by the FIDA diagnostic show that the acceleration is at four harmonics (7-10) simultaneously and it is much broader than in DIII-D. This is because of the multiple resonance layers and large orbits in NSTX. The measured spatial profile of accelerated fast ions is farther from the magnetic axis and broader than predicted by the CQL3D Fokker-Planck code, for which we conjecture that finite Larmor radius and banana-width can have significant effects on the fast ions in NSTX. To test this hypothesis, simulations with ORBIT-RF code coupled with full wave code AORSA are in progress.

  7. Design of parallel transmission pulses for simultaneous multi-slice with explicit control for peak power and local specific absorption rate

    PubMed Central

    Guérin, Bastien; Setsompop, Kawin; Ye, Huihui; Poser, Benedikt A.; Stenger, Andrew V.; Wald, Lawrence L.

    2014-01-01

    Purpose To design parallel transmit (pTx) simultaneous multi-slice (SMS) spokes pulses with explicit control for peak power, local and global specific absorption rate (SAR). Methods We designed SMS pTx least-squares and magnitude least squares spokes pulses while constraining local SAR using the virtual observation points (VOPs) compression of SAR matrices. We evaluated our approach in simulations of a head (7 T) and a body (3 T) coil with 8 channels arranged in two z-rows. Results For many of our simulations, control of average power by Tikhonov regularization of the SMS pTx spokes pulse design yielded pulses that violated hardware and SAR safety limits. On the other hand, control of peak power alone yielded pulses that violated local SAR limits. Pulses optimized with control of both local SAR and peak power satisfied all constraints and therefore had the best excitation performance under limiting power and SAR constraints. These results extend our previous results for single slice pTx excitations but are more pronounced because of the large power demands and SAR of SMS pulses. Conclusions Explicit control of local SAR and peak power is required to generate optimal SMS pTx excitations satisfying both the system's hardware limits and regulatory safety limits. PMID:24938991

  8. Fast, High-Precision Readout Circuit for Detector Arrays

    NASA Technical Reports Server (NTRS)

    Rider, David M.; Hancock, Bruce R.; Key, Richard W.; Cunningham, Thomas J.; Wrigley, Chris J.; Seshadri, Suresh; Sander, Stanley P.; Blavier, Jean-Francois L.

    2013-01-01

    The GEO-CAPE mission described in NASA's Earth Science and Applications Decadal Survey requires high spatial, temporal, and spectral resolution measurements to monitor and characterize the rapidly changing chemistry of the troposphere over North and South Americas. High-frame-rate focal plane arrays (FPAs) with many pixels are needed to enable such measurements. A high-throughput digital detector readout integrated circuit (ROIC) that meets the GEO-CAPE FPA needs has been developed, fabricated, and tested. The ROIC is based on an innovative charge integrating, fast, high-precision analog-to-digital circuit that is built into each pixel. The 128×128-pixel ROIC digitizes all 16,384 pixels simultaneously at frame rates up to 16 kHz to provide a completely digital output on a single integrated circuit at an unprecedented rate of 262 million pixels per second. The approach eliminates the need for off focal plane electronics, greatly reducing volume, mass, and power compared to conventional FPA implementations. A focal plane based on this ROIC will require less than 2 W of power on a 1×1-cm integrated circuit. The ROIC is fabricated of silicon using CMOS technology. It is designed to be indium bump bonded to a variety of detector materials including silicon PIN diodes, indium antimonide (InSb), indium gallium arsenide (In- GaAs), and mercury cadmium telluride (HgCdTe) detector arrays to provide coverage over a broad spectral range in the infrared, visible, and ultraviolet spectral ranges.

  9. Monitoring peak power and cooling energy savings of shade trees and white surfaces in the Sacramento Municipal Utility District (SMUD) service area: Project design and preliminary results

    SciTech Connect

    Akbari, H.; Bretz, S.; Hanford, J.; Rosenfeld, A.; Sailor, D.; Taha, H.; Bos, W.

    1992-12-01

    Urban areas in warm climates create summer heat islands of daily average intensity of 3--5{degrees}C, adding to discomfort and increasing air-conditioning loads. Two important factors contributing to urban heat islands are reductions in albedo (lower overall city reflectance) and loss of vegetation (less evapotranspiration). Reducing summer heat islands by planting vegetation (shade trees) and increasing surface albedos, saves cooling energy, allows down-sizing of air conditioners, lowers air-conditioning peak demand, and reduces the emission of CO{sub 2} and other pollutants from electric power plants. The focus of this multi-year project, jointly sponsored by SMUD and the California Institute for Energy Efficiency (CIEE), was to measure the direct cooling effects of trees and white surfaces (mainly roofs) in a few buildings in Sacramento. The first-year project was to design the experiment and obtain base case data. We also obtained limited post retrofit data for some sites. This report provides an overview of the project activities during the first year at six sites. The measurement period for some of the sites was limited to September and October, which are transitional cooling months in Sacramento and hence the interpretation of results only apply to this period. In one house, recoating the dark roof with a high-albedo coating rendered air conditioning unnecessary for the month of September (possible savings of up to 10 kWh per day and 2 kW of non-coincidental peak power). Savings of 50% relative to an identical base case bungalow were achieved when a school bungalow`s roof and southeast wall were coated with a high-albedo coating during the same period. Our measured data for the vegetation sites do not indicate conclusive results because shade trees were small and the cooling period was almost over. We need to collect more data over a longer cooling season in order to demonstrate savings conclusively.

  10. Interaction between high harmonic fast waves and fast ions in NSTX/NSTX-U plasmas

    NASA Astrophysics Data System (ADS)

    Bertelli, N.; Valeo, E. J.; Gorelenkova, M.; Green, D. L.; RF SciDAC Team

    2016-10-01

    Fast wave (FW) heating in the ion cyclotron range of frequency (ICRF) has been successfully used to sustain and control the fusion plasma performance, and it will likely play an important role in the ITER experiment. As demonstrated in the NSTX and DIII-D experiments the interactions between fast waves and fast ions can be so strong to significantly modify the fast ion population from neutral beam injection. In fact, it has been recently found in NSTX that FWs can modify and, under certain conditions, even suppress the energetic particle driven instabilities, such as toroidal Alfvén eigenmodes and global Alfvén eigenmodes and fishbones. This paper examines such interactions in NSTX/NSTX-U plasmas by using the recent extension of the RF full-wave code TORIC to include non-Maxwellian ions distribution functions. Particular attention is given to the evolution of the fast ions distribution function w/ and w/o RF. Tests on the RF kick-operator implemented in the Monte-Carlo particle code NUBEAM is also discussed in order to move towards a self consistent evaluation of the RF wave-field and the ion distribution functions in the TRANSP code. Work supported by US DOE Contract DE-AC02-09CH11466.

  11. Circulating pro-inflammatory cytokines are elevated and peak power output correlates with 25-hydroxyvitamin D in vitamin D insufficient adults.

    PubMed

    Barker, Tyler; Martins, Thomas B; Hill, Harry R; Kjeldsberg, Carl R; Dixon, Brian M; Schneider, Erik D; Henriksen, Vanessa T; Weaver, Lindell K

    2013-06-01

    The purpose of this study was to identify circulating cytokines, skeletal muscle strength, and peak power output in young adults with contrasting serum 25-hydroxyvitamin D (25(OH)D) concentrations. Serum 25(OH)D, inflammatory cytokines, muscle strength, and peak power output were, therefore, measured in young adults (25-42 years). Data were collected during the winter to avoid the seasonal influence on serum 25(OH)D. After serum 25(OH)D concentration measurements, subjects were separated into one of two groups: (1) vitamin D insufficient [serum 25(OH)D ≤32 ng/mL, n = 14], or (2) vitamin D sufficient [serum 25(OH)D >32 ng/mL, n = 14]. Following group allocation, serum 25(OH)D concentrations were significantly (p < 0.05) lower and pro-inflammatory cytokines [interleukin (IL)-2, IL-1β, tumor necrosis factor-α, and interferon-γ] were significantly (all p < 0.05) greater in vitamin D insufficient adults. An anti-inflammatory cytokine (i.e., IL-10; p > 0.05), peak isometric forces (p > 0.05), and peak power outputs (p > 0.05) were not significantly different between vitamin D groups. However, peak power outputs correlated with serum 25(OH)D concentrations in vitamin D insufficient (r = 0.55, p < 0.05) but not in vitamin D sufficient adults (r = -0.27, p = 0.36). Based on these data, we conclude that vitamin D insufficiency, in part, could result in pro-inflammatory stress without altering muscular strength or function in young adults. Future research investigating the causality of the correlation between low-serum 25(OH)D and peak power output in young adults is required.

  12. Design of a transportable high efficiency fast neutron spectrometer

    DOE PAGES

    Roecker, C.; Bernstein, A.; Bowden, N. S.; ...

    2016-04-12

    A transportable fast neutron detection system has been designed and constructed for measuring neutron energy spectra and flux ranging from tens to hundreds of MeV. The transportability of the spectrometer reduces the detector-related systematic bias between different neutron spectra and flux measurements, which allows for the comparison of measurements above or below ground. The spectrometer will measure neutron fluxes that are of prohibitively low intensity compared to the site-specific background rates targeted by other transportable fast neutron detection systems. To measure low intensity high-energy neutron fluxes, a conventional capture-gating technique is used for measuring neutron energies above 20 MeV andmore » a novel multiplicity technique is used for measuring neutron energies above 100 MeV. The spectrometer is composed of two Gd containing plastic scintillator detectors arranged around a lead spallation target. To calibrate and characterize the position dependent response of the spectrometer, a Monte Carlo model was developed and used in conjunction with experimental data from gamma ray sources. Multiplicity event identification algorithms were developed and used with a Cf-252 neutron multiplicity source to validate the Monte Carlo model Gd concentration and secondary neutron capture efficiency. The validated Monte Carlo model was used to predict an effective area for the multiplicity and capture gating analyses. For incident neutron energies between 100 MeV and 1000 MeV with an isotropic angular distribution, the multiplicity analysis predicted an effective area of 500 cm2 rising to 5000 cm2. For neutron energies above 20 MeV, the capture-gating analysis predicted an effective area between 1800 cm2 and 2500 cm2. As a result, the multiplicity mode was found to be sensitive to the incident neutron angular distribution.« less

  13. Design of a transportable high efficiency fast neutron spectrometer

    NASA Astrophysics Data System (ADS)

    Roecker, C.; Bernstein, A.; Bowden, N. S.; Cabrera-Palmer, B.; Dazeley, S.; Gerling, M.; Marleau, P.; Sweany, M. D.; Vetter, K.

    2016-08-01

    A transportable fast neutron detection system has been designed and constructed for measuring neutron energy spectra and flux ranging from tens to hundreds of MeV. The transportability of the spectrometer reduces the detector-related systematic bias between different neutron spectra and flux measurements, which allows for the comparison of measurements above or below ground. The spectrometer will measure neutron fluxes that are of prohibitively low intensity compared to the site-specific background rates targeted by other transportable fast neutron detection systems. To measure low intensity high-energy neutron fluxes, a conventional capture-gating technique is used for measuring neutron energies above 20 MeV and a novel multiplicity technique is used for measuring neutron energies above 100 MeV. The spectrometer is composed of two Gd containing plastic scintillator detectors arranged around a lead spallation target. To calibrate and characterize the position dependent response of the spectrometer, a Monte Carlo model was developed and used in conjunction with experimental data from gamma ray sources. Multiplicity event identification algorithms were developed and used with a Cf-252 neutron multiplicity source to validate the Monte Carlo model Gd concentration and secondary neutron capture efficiency. The validated Monte Carlo model was used to predict an effective area for the multiplicity and capture gating analyses. For incident neutron energies between 100 MeV and 1000 MeV with an isotropic angular distribution, the multiplicity analysis predicted an effective area of 500 cm2 rising to 5000 cm2. For neutron energies above 20 MeV, the capture-gating analysis predicted an effective area between 1800 cm2 and 2500 cm2. The multiplicity mode was found to be sensitive to the incident neutron angular distribution.

  14. Design of a transportable high efficiency fast neutron spectrometer

    SciTech Connect

    Roecker, C.; Bernstein, A.; Bowden, N. S.; Cabrera-Palmer, B.; Dazeley, S.; Gerling, M.; Marleau, P.; Sweany, M. D.; Vetter, K.

    2016-04-12

    A transportable fast neutron detection system has been designed and constructed for measuring neutron energy spectra and flux ranging from tens to hundreds of MeV. The transportability of the spectrometer reduces the detector-related systematic bias between different neutron spectra and flux measurements, which allows for the comparison of measurements above or below ground. The spectrometer will measure neutron fluxes that are of prohibitively low intensity compared to the site-specific background rates targeted by other transportable fast neutron detection systems. To measure low intensity high-energy neutron fluxes, a conventional capture-gating technique is used for measuring neutron energies above 20 MeV and a novel multiplicity technique is used for measuring neutron energies above 100 MeV. The spectrometer is composed of two Gd containing plastic scintillator detectors arranged around a lead spallation target. To calibrate and characterize the position dependent response of the spectrometer, a Monte Carlo model was developed and used in conjunction with experimental data from gamma ray sources. Multiplicity event identification algorithms were developed and used with a Cf-252 neutron multiplicity source to validate the Monte Carlo model Gd concentration and secondary neutron capture efficiency. The validated Monte Carlo model was used to predict an effective area for the multiplicity and capture gating analyses. For incident neutron energies between 100 MeV and 1000 MeV with an isotropic angular distribution, the multiplicity analysis predicted an effective area of 500 cm2 rising to 5000 cm2. For neutron energies above 20 MeV, the capture-gating analysis predicted an effective area between 1800 cm2 and 2500 cm2. As a result, the multiplicity mode was found to be sensitive to the incident neutron angular distribution.

  15. A high gain energy amplifier operated with fast neutrons

    SciTech Connect

    Rubbia, C.

    1995-10-01

    The basic concept and the main practical considerations of an Energy Amplifier (EA) have been exhaustively described elsewhere. Here the concept of the EA is further explored and additional schemes are described which offer a higher gain, a larger maximum power density and an extended burn-up. All these benefits stem from the use of fast neutrons, instead of thermal or epithermal ones, which was the case in the original study. The higher gain is due both to a more efficient high energy target configuration and to a larger, practical value of the multiplication factor. The higher power density results from the higher permissible neutron flux, which in turn is related to the reduced rate of {sup 233}Pa neutron captures (which, as is well known, suppress the formation of the fissile {sup 233}U fuel) and the much smaller k variations after switch-off due to {sup 233}Pa decays for a given burn-up rate. Finally a longer integrated burn-up is made possible by reduced capture rate by fission fragments of fast neutrons. In practice a 20 MW proton beam (20 mA @ 1 GeV) accelerated by a cyclotron will suffice to operate a compact EA at the level of {approx} 1 GW{sub e}. The integrated fuel burn-up can be extended in excess of 100 GW d/ton, limited by the mechanical survival of the fuel elements. Radio-Toxicity accumulated at the end of the cycle is found to be largely inferior to the one of an ordinary Reactor for the same energy produced. Schemes are proposed which make a {open_quotes}melt-down{close_quotes} virtually impossible. The conversion ratio, namely the rate of production of {sup 233}U relative to consumption is generally larger than unity, which permits production of fuel for other uses. Alternatively the neutron excess can be used to transform unwanted {open_quotes}ashes{close_quotes} into more acceptable elements.

  16. High frame rate CCD camera with fast optical shutter

    SciTech Connect

    Yates, G.J.; McDonald, T.E. Jr.; Turko, B.T.

    1998-09-01

    A high frame rate CCD camera coupled with a fast optical shutter has been designed for high repetition rate imaging applications. The design uses state-of-the-art microchannel plate image intensifier (MCPII) technology fostered/developed by Los Alamos National Laboratory to support nuclear, military, and medical research requiring high-speed imagery. Key design features include asynchronous resetting of the camera to acquire random transient images, patented real-time analog signal processing with 10-bit digitization at 40--75 MHz pixel rates, synchronized shutter exposures as short as 200pS, sustained continuous readout of 512 x 512 pixels per frame at 1--5Hz rates via parallel multiport (16-port CCD) data transfer. Salient characterization/performance test data for the prototype camera are presented, temporally and spatially resolved images obtained from range-gated LADAR field testing are included, an alternative system configuration using several cameras sequenced to deliver discrete numbers of consecutive frames at effective burst rates up to 5GHz (accomplished by time-phasing of consecutive MCPII shutter gates without overlap) is discussed. Potential applications including dynamic radiography and optical correlation will be presented.

  17. Model biases in high-burnup fast reactor simulations

    SciTech Connect

    Touran, N.; Cheatham, J.; Petroski, R.

    2012-07-01

    A new code system called the Advanced Reactor Modeling Interface (ARMI) has been developed that loosely couples multiscale, multiphysics nuclear reactor simulations to provide rapid, user-friendly, high-fidelity full systems analysis. Incorporating neutronic, thermal-hydraulic, safety/transient, fuel performance, core mechanical, and economic analyses, ARMI provides 'one-click' assessments of many multi-disciplined performance metrics and constraints that historically require iterations between many diverse experts. The capabilities of ARMI are implemented in this study to quantify neutronic biases of various modeling approximations typically made in fast reactor analysis at an equilibrium condition, after many repetitive shuffles. Sensitivities at equilibrium that result in very high discharge burnup are considered ( and >20% FIMA), as motivated by the development of the Traveling Wave Reactor. Model approximations discussed include homogenization, neutronic and depletion mesh resolution, thermal-hydraulic coupling, explicit control rod insertion, burnup-dependent cross sections, fission product model, burn chain truncation, and dynamic fuel performance. The sensitivities of these approximations on equilibrium discharge burnup, k{sub eff}, power density, delayed neutron fraction, and coolant temperature coefficient are discussed. (authors)

  18. High frequency fast wave current drive for DEMO

    NASA Astrophysics Data System (ADS)

    Koch, R.; Lerche, E.; Van Eester, D.; Nightingale, M.

    2011-12-01

    A steady-state tokamak reactor (SSTR) requires a high efficiency current drive system, from plug to driven mega-amps. RF systems working in the ion-cyclotron range of frequencies (ICRF) have high efficiency from plug to antenna but a limited current drive (CD) efficiency and centrally peaked CD profiles. The latter feature is not adequate for a SSTR where the current should be sufficiently broad to keep the central safety factor (possibly significantly) above 1. In addition, the fact that the fast wave (FW) is evanescent at the edge limits coupling, requiring high voltage operation, which makes the system dependent on plasma edge properties and prone to arcing, reducing its reliability. A possible way to overcome these weaknesses is to operate at higher frequency (10 times or more the cyclotron frequency). The advantages are: (1) The coupling can be much better (waves propagate in vacuum) if the parallel refractive index n∥ is kept below one, (2) The FW group velocity tends to align to the magnetic field, so the power circumnavigates the magnetic axis and can drive off-axis current, (3) Due to the latter property, n∥ can be upshifted along the wave propagation path, allowing low n∥ launch (hence good coupling, large CD efficiency) with ultimately good electron absorption (which requires higher n∥). Note however that the n∥ upshift is a self-organized feature, that electron absorption is in competition with α-particle absorption and that uncoupling of the FW from the lower hybrid resonance at the edge requires n∥ slightly above one. The latter possibly counterproductive features might complicate the picture. The different aspects of this potentially attractive off-axis FWCD scheme are discussed.

  19. High-quality thin graphene films from fast electrochemical exfoliation.

    PubMed

    Su, Ching-Yuan; Lu, Ang-Yu; Xu, Yanping; Chen, Fu-Rong; Khlobystov, Andrei N; Li, Lain-Jong

    2011-03-22

    Flexible and ultratransparent conductors based on graphene sheets have been considered as one promising candidate for replacing currently used indium tin oxide films that are unlikely to satisfy future needs due to their increasing cost and losses in conductivity on bending. Here we demonstrate a simple and fast electrochemical method to exfoliate graphite into thin graphene sheets, mainly AB-stacked bilayered graphene with a large lateral size (several to several tens of micrometers). The electrical properties of these exfoliated sheets are readily superior to commonly used reduced graphene oxide, which preparation typically requires many steps including oxidation of graphite and high temperature reduction. These graphene sheets dissolve in dimethyl formamide (DMF), and they can self-aggregate at air-DMF interfaces after adding water as an antisolvent due to their strong surface hydrophobicity. Interestingly, the continuous films obtained exhibit ultratransparency (∼96% transmittance), and their sheet resistance is <1k Ω/sq after a simple HNO3 treatment, superior to those based on reduced graphene oxide or graphene sheets by other exfoliation methods. Raman and STM characterizations corroborate that the graphene sheets exfoliated by our electrochemical method preserve the intrinsic structure of graphene.

  20. High-Harmonic Fast Wave (HHFW) Heating Results on NSTX

    NASA Astrophysics Data System (ADS)

    Taylor, G.; Hosea, J. C.; Leblanc, B. P.; Phillips, C. K.; Podesta, M.; Valeo, E. J.; Wilson, J. R.; Bonoli, P. T.; Harvey, R. W.; Jaeger, E. F.; Ryan, P. M.

    2010-11-01

    This talk will present recent experimental and modeling results from NSTX HHFW research. HHFW heating of low current (200 - 400 kA) plasmas has resulted in a transition to a high bootstrap current fraction, H-mode regime needed for solenoid-free ramp-up. Coupling of HHFW power to NBI H-mode plasmas has been improved with lithium wall conditioning [1], although significant rf power is measured to flow to the divertor, particularly at longer launch wavelengths. Modeling results for H-mode discharges that use a combination of HHFW and NBI heating predict a strong competition between direct electron heating and fast-ion acceleration. A double-feed upgrade of the HHFW antenna in 2009 did not improve the stand off voltage by as much as predicted and appears to be limited by RF currents induced on the antenna surface. However, the stand off voltage limit can be increased with sufficient antenna conditioning. [1] G. Taylor, et al., Phys. Plasmas 17, 056114 (2010).

  1. Formation of fast notched'' current waveforms through a high inductance

    SciTech Connect

    Spanjers, G.; Nelson, B.A.; Ribe, F.L. )

    1991-10-01

    A fast notch'' current has been produced on the (4 {mu}H) hardcore central conductor (C. M. Greenfield, M. E. Koepke, and F. L. Ribe, Phys. Fluids B {bold 2}, 133 (1990)) of the high beta Q machine, a 2.6 m theta pinch (S. O. Knox, H. Meuth, E. Sevillano, and F. L. Ribe, 3rd IEEE International Pulsed Power Conf., 1981, IEEE Publ. 81 CH1662/6, paper 3.1). With the notch circuitry, the current can be slowly ({tau}{sub 1/4} = 14 {mu}s) brought to a crowbarred dc value (20 kA) and then quickly ({tau}{sub 1/4} = 1.3 {mu}s) notched'' to a different value (typically either 0 kA or twice the dc value) and then quickly returned to the dc value. The use of a new inductively loaded spark gap switch eliminates extraneous ringing in the final crowbarred current waveform. As described here, by driving the hardcore circuit with two isolated capacitor banks, and a voltage stepup transformer, the notch current is created using spark gaps and ignitrons for switching, resulting in an inexpensive and technically simple circuit.

  2. Quantum-dot saturable absorber and Kerr-lens mode-locked Yb:KGW laser with >450  kW of peak power.

    PubMed

    Akbari, R; Zhao, H; Fedorova, K A; Rafailov, E U; Major, A

    2016-08-15

    The hybrid action of quantum-dot saturable absorber and Kerr-lens mode locking in a diode-pumped Yb:KGW laser was demonstrated. Using a quantum-dot saturable absorber with a 0.7% (0.5%) modulation depth, the mode-locked laser delivered 90 fs (93 fs) pulses with 3.2 W (2.9 W) of average power at the repetition rate of 77 MHz, corresponding to 462 kW (406 kW) of peak power and 41 nJ (38 nJ) of pulse energy. To the best of our knowledge, this represents the highest average and peak powers generated to date from quantum-dot saturable absorber-based mode-locked lasers.

  3. 1.1 MW peak power in doubly QML composite Nd:YVO4/Nd:YVO4/Nd:YVO4/KTP sub-nanosecond green laser with EO and Bi-GaAs.

    PubMed

    Li, Shixia; Li, Dechun; Zhao, Shengzhi; Li, Guiqiu; Li, Xiangyang; Qiao, Hui

    2016-02-22

    By simultaneously employing electro-optic (EO) modulator and Bi-doped GaAs, dual-loss-modulated Q-switched and mode-locked (QML) multi-segment composite Nd:YVO4/Nd:YVO4/Nd:YVO4/KTP sub-nanosecond green laser is demonstrated with low repetition rate and high peak power. When the incident pump power is up to 6.93 W, only one mode-locking pulse underneath a Q-switching envelope is generated with sub-nanosecond pulse duration at one kilohertz repetition rate. An average output power of 445 mW and a pulse duration of 399 ps are obtained with the incident pump power of 11.13 W, corresponding to a peak power of 1.115 MW which is the highest one in doubly QML sub-nanosecond green laser by now. The laser characteristics are better than those obtained with EO and GaAs. The experimental results indicate that Bi-GaAs is a promising saturable absorber for dual-loss-modulated QML laser.

  4. Tunable 975 nm nanosecond diode-laser-based master-oscillator power-amplifier system with 16.3 W peak power and narrow spectral linewidth below 10 pm.

    PubMed

    Vu, Thi Nghiem; Klehr, Andreas; Sumpf, Bernd; Wenzel, Hans; Erbert, Götz; Tränkle, Günther

    2014-09-01

    A spectrally tunable, narrow linewidth master oscillator power amplifier system emitting ns pulses with high peak power is presented. The master oscillator is a distributed feedback ridge waveguide (DFB-RW) laser, which is operated in continuous wave (CW) mode and emits at about 975 nm with a spectral line width below 10 pm. The oscillator can be tuned over a range of 0.9 nm by varying the injection current. The tapered amplifier (TA) consists of an RW section and a flared gain-guided section. The RW section of the amplifier acts as an optical gate and converts the CW input beam emitted by the DFB-RW laser into a train of short optical pulses, which are subsequently amplified by the tapered section. The width of the pulses is 8 ns at a repetition rate of 25 kHz. The peak power is 16.3 W. The TA preserves the spectral properties of the emission of the DBR-RW laser. The amplified spontaneous emission is suppressed by about 40 dB.

  5. [High frequency of dyslipidemia and impaired fasting glycemia in a high altitude Peruvian population].

    PubMed

    Málaga, Germán; Zevallos-Palacios, Claudia; Lazo, María de los Ángeles; Huayanay, Carlos

    2010-01-01

    We performed a cross sectional study in Lari (3600 m), a highland rural community from Arequipa, Peru. We evaluated a body mass index (BMI), glycemia and lipid profile in 74 over 18 year persons. The mean age was 51.7 ± 18.0 years, 62.2% were women, mean of BMI was 25.6 ± 3.7. Prevalence of hypercholesterolemia was 40.6%, "low HDL" in 77% of the population (93.5% in women vs 50% in men, p <0.001) and elevated level of LDL was 71.7%. The prevalence of impaired fasting glycemia was 27%. In conclusion, we found high prevalence of impaired fasting glycemia, hypercholesterolemia and especially "low HDL" in high altitude rural natives. These findings must be considered to realize interventions in high altitude populations to avoid future cardiovascular complications.

  6. New CO2 Sensor with High Resolution and Fast Response

    DTIC Science & Technology

    2007-11-02

    colorimetry [7]. The dominant gas phase principle is Nondispersive Infrared Sprectroscopy ( NDIR ) [8], based on specific absorption at the 4.23 µm band...to the list of important characteristics is made in Table 1. The scaling properties are favorable for all principles except NDIR . The relatively...accuracy or response time. The accuracy of the pH-based methods is limited [12], whereas all methods except possibly the NDIR have capability of fast

  7. Fast-synchronizing high-fidelity spread-spectrum receiver

    DOEpatents

    Moore, Michael Roy; Smith, Stephen Fulton; Emery, Michael Steven

    2004-06-01

    A fast-synchronizing receiver having a circuit including an equalizer configured for manipulating an analog signal; a detector in communication with the equalizer; a filter in communication with the detector; an oscillator in communication with the filter; a gate for receiving the manipulated signal; a circuit portion for synchronizing and tracking the manipulated signal; a summing circuit in communication with the circuit portion; and an output gate.

  8. Fast T1 mapping of the brain at high field using Look-Locker and fast imaging.

    PubMed

    Jiang, Ke; Zhu, Yanjie; Jia, Sen; Wu, Yin; Liu, Xin; Chung, Yiu-Cho

    2017-02-01

    This study aims to develop and evaluate a new method for fast high resolution T1 mapping of the brain based on the Look-Locker technique. Single-shot turboflash sequence with high temporal acceleration is used to sample the recovery of inverted magnetization. Multi-slice interleaved acquisition within one inversion slab is used to reduce the number of inversion pulses and hence SAR. Accuracy of the proposed method was studied using simulation and validated in phantoms. It was then evaluated in healthy volunteers and stroke patients. In-vivo results were compared to values obtained by inversion recovery fast spin echo (IR-FSE) and literatures. With the new method, T1 values in phantom experiments agreed with reference values with median error <3%. For in-vivo experiments, a T1 map was acquired in 3.35s and the T1 maps of the whole brain were acquired in 2min with two-slice interleaving, with a spatial resolution of 1.1×1.1×4mm(3). The T1 values obtained were comparable to those measured with IR-FSE and those reported in literatures. These results demonstrated the feasibility of the proposed method for fast T1 mapping of the brain in both healthy volunteers and stroke patients at 3T.

  9. 1-MW peak power, 574-kHz repetition rate picosecond pulses at 515 nm from a frequency-doubled fiber amplifier

    NASA Astrophysics Data System (ADS)

    Zou, Feng; Wang, Ziwei; Wang, Zhaokun; Bai, Yang; Li, Qiurui; Zhou, Jun

    2016-11-01

    1-MW peak power picosecond, 574-kHz repetition rate green laser at 515-nm is generated from a frequency-doubled fiber amplifier. 12-ps pulses with 13.9-μJ energy at 515 nm are achieved with a noncritically phase-matched lithium triborate (LBO) crystal through second harmonic generation of a 1030 nm infrared source. The infrared source employs ultra-large-mode-area rod-type photonic crystal fiber (Rod-PCF) for direct picosecond amplification and delivers 20-W 11.6-ps 2.97-MW pulse train with near-diffraction-limited beam quality (M2 = 1.01).

  10. The left ventricle as a mechanical engine: from Leonardo da Vinci to the echocardiographic assessment of peak power output-to-left ventricular mass.

    PubMed

    Dini, Frank L; Guarini, Giacinta; Ballo, Piercarlo; Carluccio, Erberto; Maiello, Maria; Capozza, Paola; Innelli, Pasquale; Rosa, Gian M; Palmiero, Pasquale; Galderisi, Maurizio; Razzolini, Renato; Nodari, Savina

    2013-03-01

    The interpretation of the heart as a mechanical engine dates back to the teachings of Leonardo da Vinci, who was the first to apply the laws of mechanics to the function of the heart. Similar to any mechanical engine, whose performance is proportional to the power generated with respect to weight, the left ventricle can be viewed as a power generator whose performance can be related to left ventricular mass. Stress echocardiography may provide valuable information on the relationship between cardiac performance and recruited left ventricular mass that may be used in distinguishing between adaptive and maladaptive left ventricular remodeling. Peak power output-to-mass, obtained during exercise or pharmacological stress echocardiography, is a measure that reflects the number of watts that are developed by 100 g of left ventricular mass under maximal stimulation. Power output-to-mass may be calculated as left ventricular power output per 100 g of left ventricular mass: 100× left ventricular power output divided by left ventricular mass (W/100 g). A simplified formula to calculate power output-to-mass is as follows: 0.222 × cardiac output (l/min) × mean blood pressure (mmHg)/left ventricular mass (g). When the integrity of myocardial structure is compromised, a mismatch becomes apparent between maximal cardiac power output and left ventricular mass; when this occurs, a reduction of the peak power output-to-mass index is observed.

  11. Damage testing of critical optical components for high power ultra-fast lasers

    NASA Astrophysics Data System (ADS)

    Chowdhury, Enam; Poole, Patrick; Jiang, Sheng; Taylor, Brittany; Daskalova, Rebecca; Van Woerkom, Linn; Freeman, Richard; Smith, Douglas

    2010-11-01

    Mirrors and gratings used in high power ultra fast lasers require a broad bandwidth and high damage fluence, which is essential to the design and construction of petawatt class short pulse lasers. Damage fluence of several commercially available high energy broad band dielectric mirrors with over 100 nm bandwidth at 45 degree angle of incidence, and pulse compression reflection gratings with gold coating with varying processing conditions is studied using a 25 femtosecond ultra-fast laser.

  12. Very fast motion planning for highly dexterous-articulated robots

    NASA Technical Reports Server (NTRS)

    Challou, Daniel J.; Gini, Maria; Kumar, Vipin

    1994-01-01

    Due to the inherent danger of space exploration, the need for greater use of teleoperated and autonomous robotic systems in space-based applications has long been apparent. Autonomous and semi-autonomous robotic devices have been proposed for carrying out routine functions associated with scientific experiments aboard the shuttle and space station. Finally, research into the use of such devices for planetary exploration continues. To accomplish their assigned tasks, all such autonomous and semi-autonomous devices will require the ability to move themselves through space without hitting themselves or the objects which surround them. In space it is important to execute the necessary motions correctly when they are first attempted because repositioning is expensive in terms of both time and resources (e.g., fuel). Finally, such devices will have to function in a variety of different environments. Given these constraints, a means for fast motion planning to insure the correct movement of robotic devices would be ideal. Unfortunately, motion planning algorithms are rarely used in practice because of their computational complexity. Fast methods have been developed for detecting imminent collisions, but the more general problem of motion planning remains computationally intractable. However, in this paper we show how the use of multicomputers and appropriate parallel algorithms can substantially reduce the time required to synthesize paths for dexterous articulated robots with a large number of joints. We have developed a parallel formulation of the Randomized Path Planner proposed by Barraquand and Latombe. We have shown that our parallel formulation is capable of formulating plans in a few seconds or less on various parallel architectures including: the nCUBE2 multicomputer with up to 1024 processors (nCUBE2 is a registered trademark of the nCUBE corporation), and a network of workstations.

  13. Gigawatt peak power generation in a relativistic klystron amplifier driven by 1 kW seed-power

    NASA Astrophysics Data System (ADS)

    Wu, Y.; Xie, H. Q.; Li, Z. H.; Zhang, Y. J.; Ma, Q. S.

    2013-11-01

    An S-band high gain relativistic klystron amplifier driven by kW-level RF power is proposed and studied experimentally. In the device, the RF lossy material is introduced to suppress higher mode excitation. An output power of 1.95 GW with a gain of 62.8 dB is obtained in the simulation. Under conditions of an input RF power of 1.38 kW, a microwave pulse with power of 1.9 GW, frequency of 2.86 GHz, and duration of 105 ns is generated in the experiment, and the corresponding gain is 61.4 dB.

  14. Fast, High-Resolution Terahertz Radar Imaging at 25 Meters

    NASA Technical Reports Server (NTRS)

    Cooper, Ken B.; Dengler, Robert J.; Llombart, Nuria; Talukder, Ashit; Panangadan, Anand V.; Peay, Chris S.; Siegel, Peter H.

    2010-01-01

    We report improvements in the scanning speed and standoff range of an ultra-wide bandwidth terahertz (THz) imaging radar for person-borne concealed object detection. Fast beam scanning of the single-transceiver radar is accomplished by rapidly deflecting a flat, light-weight subreflector in a confocal Gregorian optical geometry. With RF back-end improvements also implemented, the radar imaging rate has increased by a factor of about 30 compared to that achieved previously in a 4 m standoff prototype instrument. In addition, a new 100 cm diameter ellipsoidal aluminum reflector yields beam spot diameters of approximately 1 cm over a 50x50 cm field of view at a range of 25 m, although some aberrations are observed that probably arise from misaligned optics. Through-clothes images of a concealed threat at 25 m range, acquired in 5 seconds, are presented, and the impact of reduced signal-to-noise from an even faster frame rate is analyzed. These results inform the system requirements for eventually achieving sub-second or video-rate THz radar imaging.

  15. Fast high-resolution terahertz radar imaging at 25 meters

    NASA Astrophysics Data System (ADS)

    Cooper, Ken B.; Dengler, Robert J.; Llombart, Nuria; Talukder, Ashit; Panangadan, Anand V.; Peay, Chris S.; Mehdi, Imran; Siegel, Peter H.

    2010-04-01

    We report improvements in the scanning speed and standoff range of an ultra-wide bandwidth terahertz (THz) imaging radar for person-borne concealed object detection. Fast beam scanning of the single-transceiver radar is accomplished by rapidly deflecting a flat, light-weight subreflector in a confocal Gregorian optical geometry. With RF back-end improvements also implemented, the radar imaging rate has increased by a factor of about 30 compared to that achieved previously in a 4 m standoff prototype instrument. In addition, a new 100 cm diameter ellipsoidal aluminum reflector yields beam spot diameters of approximately 1 cm over a 50×50 cm field of view at a range of 25 m, although some aberrations are observed that probably arise from misaligned optics. Through-clothes images of concealed pipes at 25 m range, acquired in 5 seconds, are presented, and the impact of reduced signal-to-noise from an even faster frame rate is analyzed. These results inform the requirements for eventually achieving sub-second or video-rate THz radar imaging.

  16. Fast, High-Resolution Terahertz Radar Imaging at 25 Meters

    NASA Technical Reports Server (NTRS)

    Cooper, Ken B.; Dengler, Robert J.; Llombart, Nuria; Talukder, Ashit; Panangadan, Anand V.; Peay, Chris S.; Siegel, Peter H.

    2010-01-01

    We report improvements in the scanning speed and standoff range of an ultra-wide bandwidth terahertz (THz) imaging radar for person-borne concealed object detection. Fast beam scanning of the single-transceiver radar is accomplished by rapidly deflecting a flat, light-weight subreflector in a confocal Gregorian optical geometry. With RF back-end improvements also implemented, the radar imaging rate has increased by a factor of about 30 compared to that achieved previously in a 4 m standoff prototype instrument. In addition, a new 100 cm diameter ellipsoidal aluminum reflector yields beam spot diameters of approximately 1 cm over a 50x50 cm field of view at a range of 25 m, although some aberrations are observed that probably arise from misaligned optics. Through-clothes images of a concealed threat at 25 m range, acquired in 5 seconds, are presented, and the impact of reduced signal-to-noise from an even faster frame rate is analyzed. These results inform the system requirements for eventually achieving sub-second or video-rate THz radar imaging.

  17. High gain, Fast Scan, Broad Spectrum Parallel Beam Wavelength Dispersive X-ray Spectrometer for SEM

    SciTech Connect

    OHara, David

    2009-05-08

    During contract # DE-FG02-ER83545, Parallax Research, Inc. developed a High gain, Fast Scan Broad Spectrum Parallel beam Wavelength Dispersive X-ray Spectrometer for use on Scanning Electron Microscopes (SEM). This new spectrometer allows very fast high resolution elemental analysis of samples in an electron microscope. By comparison to previous WDS spectrometers, it can change from one energy position to another very quickly and has an extended range compared to some similar products.

  18. Fast Nonparametric Machine Learning Algorithms for High-Dimensional Massive Data and Applications

    DTIC Science & Technology

    2006-03-01

    Mapreduce : Simplified data processing on large clusters . In Symposium on Operating System Design and Implementation, 2004. 6.3.2 S. C. Deerwester, S. T...Fast Nonparametric Machine Learning Algorithms for High-dimensional Massive Data and Applications Ting Liu CMU-CS-06-124 March 2006 School of...4. TITLE AND SUBTITLE Fast Nonparametric Machine Learning Algorithms for High-dimensional Massive Data and Applications 5a. CONTRACT NUMBER 5b

  19. mrsFAST-Ultra: a compact, SNP-aware mapper for high performance sequencing applications.

    PubMed

    Hach, Faraz; Sarrafi, Iman; Hormozdiari, Farhad; Alkan, Can; Eichler, Evan E; Sahinalp, S Cenk

    2014-07-01

    High throughput sequencing (HTS) platforms generate unprecedented amounts of data that introduce challenges for processing and downstream analysis. While tools that report the 'best' mapping location of each read provide a fast way to process HTS data, they are not suitable for many types of downstream analysis such as structural variation detection, where it is important to report multiple mapping loci for each read. For this purpose we introduce mrsFAST-Ultra, a fast, cache oblivious, SNP-aware aligner that can handle the multi-mapping of HTS reads very efficiently. mrsFAST-Ultra improves mrsFAST, our first cache oblivious read aligner capable of handling multi-mapping reads, through new and compact index structures that reduce not only the overall memory usage but also the number of CPU operations per alignment. In fact the size of the index generated by mrsFAST-Ultra is 10 times smaller than that of mrsFAST. As importantly, mrsFAST-Ultra introduces new features such as being able to (i) obtain the best mapping loci for each read, and (ii) return all reads that have at most n mapping loci (within an error threshold), together with these loci, for any user specified n. Furthermore, mrsFAST-Ultra is SNP-aware, i.e. it can map reads to reference genome while discounting the mismatches that occur at common SNP locations provided by db-SNP; this significantly increases the number of reads that can be mapped to the reference genome. Notice that all of the above features are implemented within the index structure and are not simple post-processing steps and thus are performed highly efficiently. Finally, mrsFAST-Ultra utilizes multiple available cores and processors and can be tuned for various memory settings. Our results show that mrsFAST-Ultra is roughly five times faster than its predecessor mrsFAST. In comparison to newly enhanced popular tools such as Bowtie2, it is more sensitive (it can report 10 times or more mappings per read) and much faster (six times or

  20. Ultra high energy density and fast discharge nanocomposite capacitors

    NASA Astrophysics Data System (ADS)

    Tang, Haixiong; Sodano, Henry A.

    2013-04-01

    Nanocomposites containing high dielectric permittivity ceramics embedded in high breakdown strength polymers are currently of considerable interest as a solution for the development of high energy density capacitors. However, the improvement of dielectric permittivity comes at expense of the breakdown strength leading to limit the final energy density. Here, an ultra-high energy density nanocomposite was fabricated based on high aspect ratio barium strontium titanate nanowires. The pyroelectric phase Ba0.2Sr0.8TiO3 was chosen for the nanowires combined with quenched PVDF to fabricate high energy density nanocomposite. The energy density with 7.5% Ba0.2Sr0.8TiO3 nanowires reached 14.86 J/cc at 450 MV/m, which represented a 42.9% increase in comparison to the PVDF with an energy density of 10.4 J/cc at the same electric field. The capacitors have 1138% greater than higher energy density than commercial biaxial oriented polypropylene capacitors (1.2 J/cc at 640). These results demonstrate that the high aspect ratio nanowires can be used to produce nanocomposite capacitors with greater performance than the neat polymers thus providing a novel process for the development of future pulsed-power capacitors.

  1. Effects of 8-week in-season upper and lower limb heavy resistance training on the peak power, throwing velocity, and sprint performance of elite male handball players.

    PubMed

    Hermassi, Souhail; Chelly, Mohamed Souhaiel; Tabka, Zouhair; Shephard, Roy J; Chamari, Karim

    2011-09-01

    The aims of this study were to test the potential of in-season heavy upper and lower limb strength training to enhance peak power output (Wpeak), vertical jump, and handball related field performance in elite male handball players who were apparently already well trained, and to assess any adverse effects on sprint velocity. Twenty-four competitors were divided randomly between a heavy resistance (HR) group (age 20 ± 0.7 years) and a control group (C; age 20 ± 0.1 years). Resistance training sessions were performed twice a week for 8 weeks. Performance was assessed before and after conditioning. Peak power (W(peak)) was determined by cycle ergometer; vertical squat jump (SJ) and countermovement jump (CMJ); video analyses assessed velocities during the first step (V(1S)), the first 5 m (V(5m)), and between 25 and 30 m (V(peak)) of a 30-m sprint. Upper limb bench press and pull-over exercises and lower limb back half squats were performed to 1-repetition maximum (1RM). Upper limb, leg, and thigh muscle volumes and mean thigh cross-sectional area (CSA) were assessed by anthropometry. W(peak) (W) for both limbs (p < 0.001), vertical jump height (p < 0.01 for both SJ and CMJ), 1RM (p < 0.001 for both upper and lower limbs) and sprint velocities (p < 0.01 for V(1S) and V(5m); p < 0.001 for V(peak)) improved in the HR group. Upper body, leg, and thigh muscle volumes and thigh CSA also increased significantly after strength training. We conclude that in-season biweekly heavy back half-squat, pull-over, and bench-press exercises can be commended to elite male handball players as improving many measures of handball-related performance without adverse effects upon speed of movement.

  2. Current drive with combined electron cyclotron wave and high harmonic fast wave in tokamak plasmas

    NASA Astrophysics Data System (ADS)

    Li, J. C.; Gong, X. Y.; Dong, J. Q.; Wang, J.; Zhang, N.; Zheng, P. W.; Yin, C. Y.

    2016-12-01

    The current driven by combined electron cyclotron wave (ECW) and high harmonic fast wave is investigated using the GENRAY/CQL3D package. It is shown that no significant synergetic current is found in a range of cases with a combined ECW and fast wave (FW). This result is consistent with a previous study [Harvey et al., in Proceedings of IAEA TCM on Fast Wave Current Drive in Reactor Scale Tokamaks (Synergy and Complimentarily with LHCD and ECRH), Arles, France, IAEA, Vienna, 1991]. However, a positive synergy effect does appear with the FW in the lower hybrid range of frequencies. This positive synergy effect can be explained using a picture of the electron distribution function induced by the ECW and a very high harmonic fast wave (helicon). The dependence of the synergy effect on the radial position of the power deposition, the wave power, the wave frequency, and the parallel refractive index is also analyzed, both numerically and physically.

  3. Fast calibration of high-order adaptive optics systems.

    PubMed

    Kasper, Markus; Fedrigo, Enrico; Looze, Douglas P; Bonnet, Henri; Ivanescu, Liviu; Oberti, Sylvain

    2004-06-01

    We present a new method of calibrating adaptive optics systems that greatly reduces the required calibration time or, equivalently, improves the signal-to-noise ratio. The method uses an optimized actuation scheme with Hadamard patterns and does not scale with the number of actuators for a given noise level in the wavefront sensor channels. It is therefore highly desirable for high-order systems and/or adaptive secondary systems on a telescope without a Gregorian focal plane. In the latter case, the measurement noise is increased by the effects of the turbulent atmosphere when one is calibrating on a natural guide star.

  4. Polycrystalline CVD diamond detector: Fast response and high sensitivity with large area

    SciTech Connect

    Liu, Linyue Zhang, Xianpeng; Zhong, Yunhong; Ouyang, Xiaoping Zhang, Jianfu

    2014-01-15

    Polycrystalline diamond was successfully used to fabricate a large area (diameter up to 46 mm) radiation detector. It was proven that the developed detector shows a fast pulsed response time and a high sensitivity, therefore its rise time is lower than 5 ns, which is two times faster than that of a Si-PIN detector of the same size. And because of the large sensitive area, this detector shows good dominance in fast pulsed and low density radiation detection.

  5. High Temperature Ultrasonic Transducers for In-Service Inspection of Liquid Metal Fast Reactors

    SciTech Connect

    Griffin, Jeffrey W.; Posakony, Gerald J.; Harris, Robert V.; Baldwin, David L.; Jones, Anthony M.; Bond, Leonard J.

    2011-12-31

    In-service inspection of liquid metal (sodium) fast reactors requires the use of ultrasonic transducers capable of operating at high temperatures (>200°C), high gamma radiation fields, and the chemically reactive liquid sodium environment. In the early- to mid-1970s, the U.S. Atomic Energy Commission supported development of high-temperature, submersible single-element transducers, used for scanning and under-sodium imaging in the Fast Flux Test Facility and the Clinch River Breeder Reactor. Current work is building on this technology to develop the next generation of high-temperature linear ultrasonic transducer arrays for under-sodium viewing and in-service inspections.

  6. High efficiency off-axis current drive by high frequency fast waves

    SciTech Connect

    Prater, R.; Pinsker, R. I.; Moeller, C. P.; Porkolab, M.; Vdovin, V.

    2014-02-12

    Modeling work shows that current drive can be done off-axis with high efficiency, as required for FNSF and DEMO, by using very high harmonic fast waves (“helicons” or “whistlers”). The modeling indicates that plasmas with high electron beta are needed in order for the current drive to take place off-axis, making DIII-D a highly suitable test vehicle for this process. The calculations show that the driven current is not very sensitive to the launched value of n{sub ∥}, a result that can be understood from examination of the evolution of n{sub ∥} as the waves propagate in the plasma. Because of this insensitivity, relatively large values (∼3) of n{sub ∥} can be launched, thereby avoiding some of the problems with mode conversion in the boundary found in some previous experiments. Use of a traveling wave antenna provides a very narrow n{sub ∥} spectrum, which also helps avoid mode conversion.

  7. Characterization of the fast electrons distribution produced in a high intensity laser target interaction

    SciTech Connect

    Westover, B.; Chen, C. D.; Patel, P. K.; McLean, H.; Beg, F. N.

    2014-03-15

    Experiments on the Titan laser (∼150 J, 0.7 ps, 2 × 10{sup 20} W cm{sup −2}) at the Lawrence Livermore National Laboratory were carried out in order to study the properties of fast electrons produced by high-intensity, short pulse laser interacting with matter under conditions relevant to Fast Ignition. Bremsstrahlung x-rays produced by these fast electrons were measured by a set of compact filter-stack based x-ray detectors placed at three angles with respect to the target. The measured bremsstrahlung signal allows a characterization of the fast electron beam spectrum, conversion efficiency of laser energy into fast electron kinetic energy and angular distribution. A Monte Carlo code Integrated Tiger Series was used to model the bremsstrahlung signal and infer a laser to fast electron conversion efficiency of 30%, an electron slope temperature of about 2.2 MeV, and a mean divergence angle of 39°. Simulations were also performed with the hybrid transport code ZUMA which includes fields in the target. In this case, a conversion efficiency of laser energy to fast electron energy of 34% and a slope temperature between 1.5 MeV and 4 MeV depending on the angle between the target normal direction and the measuring spectrometer are found. The observed temperature of the bremsstrahlung spectrum, and therefore the inferred electron spectrum are found to be angle dependent.

  8. High-current, fast-switching transistor development

    NASA Technical Reports Server (NTRS)

    Hower, P. L.

    1981-01-01

    The design, wafer-processing techniques, and various measurements which include forward safe operating area, dc characteristics, and switching times are described for a larger-diameter (33) transistor. An improved base contact for equalizing the base-emitter voltage at high currents was developed along with an improved emitter contact preform which increases the silicon area available for current conduction. The electrical performance achieved is consistent with the proposed optimum design.

  9. High rate, fast timing Glass RPC for the high η CMS muon detectors

    NASA Astrophysics Data System (ADS)

    Lagarde, F.; Gouzevitch, M.; Laktineh, I.; Buridon, V.; Chen, X.; Combaret, C.; Eynard, A.; Germani, L.; Grenier, G.; Mathez, H.; Mirabito, L.; Petrukhin, A.; Steen, A.; Tromeur, W.; Wang, Y.; Gong, A.; Moreau, N.; de la Taille, C.; Dulucq, F.; Cimmino, A.; Crucy, S.; Fagot, A.; Gul, M.; Rios, A. A. O.; Tytgat, M.; Zaganidis, N.; Aly, S.; Assran, Y.; Radi, A.; Sayed, A.; Singh, G.; Abbrescia, M.; Iaselli, G.; Maggi, M.; Pugliese, G.; Verwilligen, P.; Van Doninck, W.; Colafranceschi, S.; Sharma, A.; Benussi, L.; Bianco, S.; Piccolo, D.; Primavera, F.; Bhatnagar, V.; Kumari, R.; Mehta, A.; Singh, J.; Ahmad, A.; Ahmed, W.; Asghar, H. M. I.; Awan, I. M.; Hoorani, R.; Muhammad, S.; Shahzad, H.; Shah, M. A.; Cho, S. W.; Choi, S. Y.; Hong, B.; Kang, M. H.; Lee, K. S.; Lim, J. H.; Park, S. K.; Kim, M. S.; Carpinteyro Bernardino, S.; Pedraza, I.; Uribe Estrada, C.; Carrillo Moreno, S.; Vazquez Valencia, F.; Pant, L. M.; Buontempo, S.; Cavallo, N.; Esposito, M.; Fabozzi, F.; Lanza, G.; Orso, I.; Lista, L.; Meola, S.; Merola, M.; Paolucci, P.; Thyssen, F.; Braghieri, A.; Magnani, A.; Montagna, P.; Riccardi, C.; Salvini, P.; Vai, I.; Vitulo, P.; Ban, Y.; Qian, S. J.; Choi, M.; Choi, Y.; Goh, J.; Kim, D.; Aleksandrov, A.; Hadjiiska, R.; Iaydjiev, P.; Rodozov, M.; Stoykova, S.; Sultanov, G.; Vutova, M.; Dimitrov, A.; Litov, L.; Pavlov, B.; Petkov, P.; Bagaturia, I.; Lomidze, D.; Avila, C.; Cabrera, A.; Sanabria, J. C.; Crotty, I.; Vaitkus, J.

    2016-09-01

    The HL-LHC phase is designed to increase by an order of magnitude the amount of data to be collected by the LHC experiments. To achieve this goal in a reasonable time scale the instantaneous luminosity would also increase by an order of magnitude up to 6 · 1034 cm-2s-1. The region of the forward muon spectrometer (|η| > 1.6) is not equipped with RPC stations. The increase of the expected particles flux up to 2 kHz/cm2 (including a safety factor 3) motivates the installation of RPC chambers to guarantee redundancy with the CSC chambers already present. The current CMS RPC technology cannot sustain the expected background level. The new technology that will be chosen should have a high rate capability and provide a good spatial and timing resolution. A new generation of Glass-RPC (GRPC) using low-resistivity glass is proposed to equip at least the two most far away of the four high η muon stations of CMS. First the design of small size prototypes and studies of their performance in high-rate particles flux are presented. Then the proposed designs for large size chambers and their fast-timing electronic readout are examined and preliminary results are provided.

  10. Qubit Architecture with High Coherence and Fast Tunable Coupling

    NASA Astrophysics Data System (ADS)

    Chen, Yu; Neill, C.; Roushan, P.; Leung, N.; Fang, M.; Barends, R.; Kelly, J.; Campbell, B.; Chen, Z.; Chiaro, B.; Dunsworth, A.; Jeffrey, E.; Megrant, A.; Mutus, J. Y.; O'Malley, P. J. J.; Quintana, C. M.; Sank, D.; Vainsencher, A.; Wenner, J.; White, T. C.; Geller, Michael R.; Cleland, A. N.; Martinis, John M.

    2014-11-01

    We introduce a superconducting qubit architecture that combines high-coherence qubits and tunable qubit-qubit coupling. With the ability to set the coupling to zero, we demonstrate that this architecture is protected from the frequency crowding problems that arise from fixed coupling. More importantly, the coupling can be tuned dynamically with nanosecond resolution, making this architecture a versatile platform with applications ranging from quantum logic gates to quantum simulation. We illustrate the advantages of dynamical coupling by implementing a novel adiabatic controlled-z gate, with a speed approaching that of single-qubit gates. Integrating coherence and scalable control, the introduced qubit architecture provides a promising path towards large-scale quantum computation and simulation.

  11. Development of the Fast Scintillation Detector with Programmable High Voltage Adjustment Suitable for Moessbauer Spectroscopy

    SciTech Connect

    Prochazka, R.; Frydrych, J.; Pechousek, J.

    2010-07-13

    This work is focused on a development of a compact fast scintillation detector suitable for Moessbauer spectroscopy (low energy X-ray/{gamma}-ray detection) where high counting rates are inevitable. Optimization of this part was necessary for a reliable function, better time resolution and to avoid a detector pulses pile-up effect. The pile-up effect decreases the measurement performance, significantly depends on the source activity and also on the pulse duration. Our new detection unit includes a fast scintillation crystal YAP:Ce, an R6095 photomultiplier tube, a high voltage power supply socket C9028-01 assembly, an AD5252 digital potentiometer with an I2C interface and an AD8000 ultra fast operation preamplifier. The main advantages of this solution lie in a short pulse duration (less than 200 ns), stable operation for high activities, programmable gain of the high voltage supply and compact design in the aluminum housing.

  12. Fast engineering optimization: A novel highly effective control parameterization approach for industrial dynamic processes.

    PubMed

    Liu, Ping; Li, Guodong; Liu, Xinggao

    2015-09-01

    Control vector parameterization (CVP) is an important approach of the engineering optimization for the industrial dynamic processes. However, its major defect, the low optimization efficiency caused by calculating the relevant differential equations in the generated nonlinear programming (NLP) problem repeatedly, limits its wide application in the engineering optimization for the industrial dynamic processes. A novel highly effective control parameterization approach, fast-CVP, is first proposed to improve the optimization efficiency for industrial dynamic processes, where the costate gradient formulae is employed and a fast approximate scheme is presented to solve the differential equations in dynamic process simulation. Three well-known engineering optimization benchmark problems of the industrial dynamic processes are demonstrated as illustration. The research results show that the proposed fast approach achieves a fine performance that at least 90% of the computation time can be saved in contrast to the traditional CVP method, which reveals the effectiveness of the proposed fast engineering optimization approach for the industrial dynamic processes.

  13. Desulphurization of lignites by slow, fast, and flash pyrolysis and high intensity dry magnetic separation

    SciTech Connect

    Koca, H.; Kockar, O.M.; Koca, S.

    2007-07-01

    Slow, fast and flash pyrolysis followed by high intensity dry magnetic (HIDM) separation experiments were conducted to obtain improved solid fuels. Pyrolysis experiments were performed in three different apparatus, and important parameters of processes, temperature, particle size, residence time and heating rate were studied to determine the optimum conditions. Desulphurization of lignites by flash pyrolysis is more successful than slow and fast pyrolysis. At optimum conditions of pyrolysis, up to 58.15, 60.24, and 62.31% sulphur reductions were obtained in slow, fast and flash pyrolysis, respectively. Char, obtained from the pyrolysis experiments, was further cleaned by a Permroll HIDM separator. Sulphur reduction enhanced up to 82.68, 84.40, and 86.55% in the char of slow, fast and flash pyrolysis, respectively.

  14. Determinants of Fast Food Consumption among Iranian High School Students Based on Planned Behavior Theory

    PubMed Central

    Sharifirad, Gholamreza; Yarmohammadi, Parastoo; Azadbakht, Leila; Morowatisharifabad, Mohammad Ali; Hassanzadeh, Akbar

    2013-01-01

    Objective. This study was conducted to identify some factors (beliefs and norms) which are related to fast food consumption among high school students in Isfahan, Iran. We used the framework of the theory planned behavior (TPB) to predict this behavior. Subjects & Methods. Cross-sectional data were available from high school students (n = 521) who were recruited by cluster randomized sampling. All of the students completed a questionnaire assessing variables of standard TPB model including attitude, subjective norms, perceived behavior control (PBC), and the additional variables past behavior, actual behavior control (ABC). Results. The TPB variables explained 25.7% of the variance in intentions with positive attitude as the strongest (β = 0.31, P < 0.001) and subjective norms as the weakest (β = 0.29, P < 0.001) determinant. Concurrently, intentions accounted for 6% of the variance for fast food consumption. Past behavior and ABC accounted for an additional amount of 20.4% of the variance in fast food consumption. Conclusion. Overall, the present study suggests that the TPB model is useful in predicting related beliefs and norms to the fast food consumption among adolescents. Subjective norms in TPB model and past behavior in TPB model with additional variables (past behavior and actual behavior control) were the most powerful predictors of fast food consumption. Therefore, TPB model may be a useful framework for planning intervention programs to reduce fast food consumption by students. PMID:23936635

  15. Determinants of fast food consumption among Iranian high school students based on planned behavior theory.

    PubMed

    Sharifirad, Gholamreza; Yarmohammadi, Parastoo; Azadbakht, Leila; Morowatisharifabad, Mohammad Ali; Hassanzadeh, Akbar

    2013-01-01

    This study was conducted to identify some factors (beliefs and norms) which are related to fast food consumption among high school students in Isfahan, Iran. We used the framework of the theory planned behavior (TPB) to predict this behavior. Cross-sectional data were available from high school students (n = 521) who were recruited by cluster randomized sampling. All of the students completed a questionnaire assessing variables of standard TPB model including attitude, subjective norms, perceived behavior control (PBC), and the additional variables past behavior, actual behavior control (ABC). The TPB variables explained 25.7% of the variance in intentions with positive attitude as the strongest (β = 0.31, P < 0.001) and subjective norms as the weakest (β = 0.29, P < 0.001) determinant. Concurrently, intentions accounted for 6% of the variance for fast food consumption. Past behavior and ABC accounted for an additional amount of 20.4% of the variance in fast food consumption. Overall, the present study suggests that the TPB model is useful in predicting related beliefs and norms to the fast food consumption among adolescents. Subjective norms in TPB model and past behavior in TPB model with additional variables (past behavior and actual behavior control) were the most powerful predictors of fast food consumption. Therefore, TPB model may be a useful framework for planning intervention programs to reduce fast food consumption by students.

  16. Sympathetic Tone Induced by High Acoustic Tempo Requires Fast Respiration.

    PubMed

    Watanabe, Ken; Ooishi, Yuuki; Kashino, Makio

    2015-01-01

    Many studies have revealed the influences of music, and particularly its tempo, on the autonomic nervous system (ANS) and respiration patterns. Since there is the interaction between the ANS and the respiratory system, namely sympatho-respiratory coupling, it is possible that the effect of musical tempo on the ANS is modulated by the respiratory system. Therefore, we investigated the effects of the relationship between musical tempo and respiratory rate on the ANS. Fifty-two healthy people aged 18-35 years participated in this study. Their respiratory rates were controlled by using a silent electronic metronome and they listened to simple drum sounds with a constant tempo. We varied the respiratory rate-acoustic tempo combination. The respiratory rate was controlled at 15 or 20 cycles per minute (CPM) and the acoustic tempo was 60 or 80 beats per minute (BPM) or the environment was silent. Electrocardiograms and an elastic chest band were used to measure the heart rate and respiratory rate, respectively. The mean heart rate and heart rate variability (HRV) were regarded as indices of ANS activity. We observed a significant increase in the mean heart rate and the low (0.04-0.15 Hz) to high (0.15-0.40 Hz) frequency ratio of HRV, only when the respiratory rate was controlled at 20 CPM and the acoustic tempo was 80 BPM. We suggest that the effect of acoustic tempo on the sympathetic tone is modulated by the respiratory system.

  17. Fast-Paced High School Science for the Academically Talented: A Six-Year Perspective.

    ERIC Educational Resources Information Center

    Lynch, Sharon J.

    1992-01-01

    This study of 905 academically talented students (ages 12-16) who completed a 1-year course in high school biology, chemistry, or physics in a 3-week summer program found that the fast-paced courses effectively prepared subjects to accelerate in science and that talented students could begin high school sciences earlier than generally allowed.…

  18. Precise reconstruction of fast moving cardiac valve in high frame rate synthetic transmit aperture ultrasound imaging

    NASA Astrophysics Data System (ADS)

    Suzuki, Mayumi; Ikeda, Teiichiro; Ishihara, Chizue; Takano, Shinta; Masuzawa, Hiroshi

    2016-04-01

    To diagnose heart valve incompetence, i.e., one of the most serious cardiac dysfunctions, it is essential to obtain images of fast-moving valves at high spatial and temporal resolution. Ultrasound synthetic transmit aperture (STA) imaging has the potential to achieve high spatial resolution by synthesizing multiple pre-beamformed images obtained with corresponding multiple transmissions. However, applying STA to fast-moving targets is difficult due to serious target deformation. We propose a high-frame-rate STA (fast STA) imaging method that uses a reduced number of transmission events needed for each image. Fast STA is expected to suppress deformation of moving targets; however, it may result in deteriorated spatial resolution. In this study, we conducted a simulation study to evaluate fast STA. We quantitatively evaluated the reduction in deformation and deterioration of spatial resolution with a model involving a radially moving valve at the maximum speed of 0.5 m/s. The simulated raw channel data of the valve phantom was processed with offline beamforming programs. We compared B-mode images obtained through single received-line in a transmission (SRT) method, STA, and fast STA. The results show that fast STA with four-times-reduced events is superior in reconstructing the original shape of the moving valve to other methods. The accuracy of valve location is 97 and 100% better than those with SRT and STA, respectively. The resolution deterioration was found to be below the annoyance threshold considering the improved performance of the shape reconstruction. The obtained results are promising for providing more precise diagnostic information on cardiovascular diseases.

  19. Visual saliency-based fast intracoding algorithm for high efficiency video coding

    NASA Astrophysics Data System (ADS)

    Zhou, Xin; Shi, Guangming; Zhou, Wei; Duan, Zhemin

    2017-01-01

    Intraprediction has been significantly improved in high efficiency video coding over H.264/AVC with quad-tree-based coding unit (CU) structure from size 64×64 to 8×8 and more prediction modes. However, these techniques cause a dramatic increase in computational complexity. An intracoding algorithm is proposed that consists of perceptual fast CU size decision algorithm and fast intraprediction mode decision algorithm. First, based on the visual saliency detection, an adaptive and fast CU size decision method is proposed to alleviate intraencoding complexity. Furthermore, a fast intraprediction mode decision algorithm with step halving rough mode decision method and early modes pruning algorithm is presented to selectively check the potential modes and effectively reduce the complexity of computation. Experimental results show that our proposed fast method reduces the computational complexity of the current HM to about 57% in encoding time with only 0.37% increases in BD rate. Meanwhile, the proposed fast algorithm has reasonable peak signal-to-noise ratio losses and nearly the same subjective perceptual quality.

  20. High-speed scanning interferometric focusing by fast measurement of binary transmission matrix for channel demixing.

    PubMed

    Tao, Xiaodong; Bodington, Dare; Reinig, Marc; Kubby, Joel

    2015-06-01

    Using the fast measurement of a binary transmission matrix and a digital micromirror device, we demonstrate high-speed interferometric focusing through highly dynamic scattering media with binary intensity modulation. The scanning of speckles for reference optimization gives stable focusing, which can be used for focusing through a fast changing media or two dimensional scanning through a slowly changing scattering media. The system allows dynamic focusing at 12.5 Hz with 1024 input modes, and more than 60 times intensity enhancement. It was tested with a moving diffuser, a mouse brain and skull tissue. The experiment with a live drosophila embryo shows its potential in compensating dynamic scattering in live biological tissue.

  1. Diode-pumped ultrafast Yb:KGW laser with 56 fs pulses and multi-100 kW peak power based on SESAM and Kerr-lens mode locking

    NASA Astrophysics Data System (ADS)

    Akbari, R.; Fedorova, K. A.; Rafailov, E. U.; Major, A.

    2017-04-01

    A high-power sub-60 fs mode-locked diode-pumped Yb:KGW laser based on hybrid action of an InGaAs quantum-dot saturable absorber mirror and Kerr-lens mode locking was demonstrated. The laser delivered 56 fs pulses with 1.95 W of average power corresponding to 450 kW of peak power. The width of the generated laser spectrum was 20.5 nm, which was near the gain bandwidth limit of the Yb:KGW crystal. To the best of our knowledge, these are the shortest pulses generated from the monoclinic double tungstate crystals (and Yb:KGW laser crystal in particular) and the most powerful in the sub-60 fs regime. At the same time, they are also the shortest pulses produced to date with the help of a quantum-dot-based saturable absorber. High-power operation with a pulse duration of 90 fs and 2.85 W of average output power was also demonstrated.

  2. Intermittent Theta Burst Over M1 May Increase Peak Power of a Wingate Anaerobic Test and Prevent the Reduction of Voluntary Activation Measured with Transcranial Magnetic Stimulation

    PubMed Central

    Giboin, Louis-Solal; Thumm, Patrick; Bertschinger, Raphael; Gruber, Markus

    2016-01-01

    Despite the potential of repetitive transcranial magnetic stimulation (rTMS) to improve performances in patients suffering from motor neuronal afflictions, its effect on motor performance enhancement in healthy subjects during a specific sport task is still unknown. We hypothesized that after an intermittent theta burst (iTBS) treatment, performance during the Wingate Anaerobic Test (WAnT) will increase and supraspinal fatigue following the exercise will be lower in comparison to a control treatment. Ten subjects participated in two randomized experiments consisting of a WAnT 5 min after either an iTBS or a control treatment. We determined voluntary activation (VA) of the right knee extensors with TMS (VATMS) and with peripheral nerve stimulation (VAPNS) of the femoral nerve, before and after the WAnT. T-tests were applied to the WAnT results and a two way within subject ANOVA was applied to VA results. The iTBS treatment increased the peak power and the maximum pedalling cadence and suppressed the reduction of VATMS following the WAnT compared to the control treatment. No behavioral changes related to fatigue (mean power and fatigue index) were observed. These results indicate for the first time that iTBS could be used as a potential intervention to improve anaerobic performance in a sport specific task. PMID:27486391

  3. Intermittent Theta Burst Over M1 May Increase Peak Power of a Wingate Anaerobic Test and Prevent the Reduction of Voluntary Activation Measured with Transcranial Magnetic Stimulation.

    PubMed

    Giboin, Louis-Solal; Thumm, Patrick; Bertschinger, Raphael; Gruber, Markus

    2016-01-01

    Despite the potential of repetitive transcranial magnetic stimulation (rTMS) to improve performances in patients suffering from motor neuronal afflictions, its effect on motor performance enhancement in healthy subjects during a specific sport task is still unknown. We hypothesized that after an intermittent theta burst (iTBS) treatment, performance during the Wingate Anaerobic Test (WAnT) will increase and supraspinal fatigue following the exercise will be lower in comparison to a control treatment. Ten subjects participated in two randomized experiments consisting of a WAnT 5 min after either an iTBS or a control treatment. We determined voluntary activation (VA) of the right knee extensors with TMS (VATMS) and with peripheral nerve stimulation (VAPNS) of the femoral nerve, before and after the WAnT. T-tests were applied to the WAnT results and a two way within subject ANOVA was applied to VA results. The iTBS treatment increased the peak power and the maximum pedalling cadence and suppressed the reduction of VATMS following the WAnT compared to the control treatment. No behavioral changes related to fatigue (mean power and fatigue index) were observed. These results indicate for the first time that iTBS could be used as a potential intervention to improve anaerobic performance in a sport specific task.

  4. Fibre amplifier based on an ytterbium-doped active tapered fibre for the generation of megawatt peak power ultrashort optical pulses

    SciTech Connect

    Koptev, M Yu; Anashkina, E A; Lipatov, D S; Andrianov, A V; Muravyev, S V; Kim, A V; Bobkov, K K; Likhachev, M E; Levchenko, A E; Aleshkina, S S; Semjonov, S L; Denisov, A N; Bubnov, M M; Laptev, A Yu; Gur'yanov, A N

    2015-05-31

    We report a new ytterbium-doped active tapered fibre used in the output amplifier stage of a fibre laser system for the generation of megawatt peak power ultrashort pulses in the microjoule energy range. The tapered fibre is single-mode at its input end (core and cladding diameters of 10 and 80 μm) and multimode at its output end (diameters of 45 and 430 μm), but ultrashort pulses are amplified in a quasi-single-mode regime. Using a hybrid Er/Yb fibre system comprising an erbium master oscillator and amplifier at a wavelength near 1.5 μm, a nonlinear wavelength converter to the 1 μm range and a three-stage ytterbium-doped fibre amplifier, we obtained pulses of 1 μJ energy and 7 ps duration, which were then compressed by a grating-pair dispersion compressor with 60% efficiency to a 130 fs duration, approaching the transform-limited pulse duration. The present experimental data agree well with numerical simulation results for pulse amplification in the threestage amplifier. (extreme light fields and their applications)

  5. Effects of lower-limb strength training on agility, repeated sprinting with changes of direction, leg peak power, and neuromuscular adaptations of soccer players.

    PubMed

    Hammami, Mehréz; Negra, Yassine; Billaut, François; Hermassi, Souhail; Shephard, Roy J; Chelly, Mohamed Souhaiel

    2017-01-24

    We examined the effects on explosive muscular performance of incorporating 8 weeks strength training into the preparation of junior male soccer players, allocating subjects between an experimental group (E, n=19) and a matched control group (C, n=12). Controls maintained their regular training program, but the experimental group replaced a part of this schedule by strength training. Performance was assessed using running times (5m, 10m, 20m, 30 and 40m), a sprint test with 180° turns (S180°), a 9-3-6-3-9 m sprint with backward and forward running (SBF), a 4 x 5 m sprint test with turns, repeated shuttle sprinting, repeated changes of direction, squat (SJ) and counter-movement (CMJ) jumping, back half-squatting, and a force-velocity test. Electromyographic (EMG) activity of the vastus lateralis (VL), vastus medialis (VM) and rectus femoris (RF) muscles was recorded during jumping. Two-way ANOVA showed significant gains in E relative to C during the straight sprint (all distances). Scores of E increased substantially (p≤0.01) on S4 x 5 and SBF, and moderately on S180°. Leg peak power, SJ and CMJ were also enhanced, with significant increases in EMG activity. However, repeated-sprint parameters showed no significant changes. We conclude that biweekly strength training improves key components of performance in junior soccer players relative to standard in-season training.

  6. Pulsed Yb:fiber system capable of >250kW peak power with tunable pulses in the 50ps to 1.5ns range

    NASA Astrophysics Data System (ADS)

    McComb, Timothy S.; Lowder, Tyson L.; Leadbetter, Vickie; Reynolds, Mitch; Saracco, Matthieu J.; Hutchinson, Joel; Green, Jared; McCal, Dennis; Burkholder, Gary; Kutscha, Tim; Dittli, Adam; Hamilton, Chuck; Kliner, Dahv A. V.; Randall, Matthew; Fanning, Geoff; Bell, Jake

    2013-03-01

    We have demonstrated a pulsed 1064 nm PM Yb:fiber laser system incorporating a seed source with a tunable pulse repetition rate and pulse duration and a multistage fiber amplifier, ending in a large core (>650 μm2 mode field area), tapered fiber amplifier. The amplifier chain is all-fiber, with the exception of the final amplifier's pump combiner, allowing robust, compact packaging. The air-cooled laser system is rated for >60 W of average power and beam quality of M2 < 1.3 at repetition rates below 100 kHz to 10's of MHz, with pulses discretely tunable over a range spanning 50 ps to greater than 1.5 ns. Maximum pulse energies, limited by the onset of self phase modulation and stimulated Raman scattering, are greater than 12.5 μJ at 50 ps and 375 μJ at 1.5 ns , corresponding to >250 kW peak power across the pulse tuning range. We present frequency conversion to 532 nm with efficiency greater than 70% and conversion to UV via frequency tripling, with initial feasibility experiments showing >30% UV conversion efficiency. Application results of the laser in scribing, thin film removal and micro-machining will be discussed.

  7. Fast-Ion Losses due to High-Frequency MHD Perturbations in the ASDEX Upgrade Tokamak

    SciTech Connect

    Garcia-Munoz, M.; Fahrbach, H.-U.; Guenter, S.; Igochine, V.; Maraschek, M.; Zohm, H.; Mantsinen, M. J.; Martin, P.; Piovesan, P.; Sassenberg, K.

    2008-02-08

    Time-resolved energy and pitch angle measurements of fast-ion losses correlated in frequency and phase with high-frequency magnetohydrodynamic perturbations have been obtained for the first time in a magnetic fusion device and are presented here. A detailed analysis of fast-ion losses due to toroidal Alfven eigenmodes has revealed the existence of a new core-localized magnetohydrodynamic perturbation, the sierpes mode. The sierpes mode is a non-Alfvenic instability which dominates the losses of fast ions in ion cyclotron resonance heated discharges, and it is named for its footprint in the spectrograms ('sierpes' means 'snake' in Spanish). The sierpes mode has been reconstructed by means of highly resolved multichord soft-x-ray measurements.

  8. SECONDARY ELECTRON TRAJECTORIES IN HIGH-GRADIENT VACUUM INSULATORS WITH FAST HIGH-VOLTAGE PULSES

    SciTech Connect

    Chen, Y; Blackfield, D; Nelson, S D; Poole, B

    2010-04-21

    Vacuum insulators composed of alternating layers of metal and dielectric, known as high-gradient insulators (HGIs), have been shown to withstand higher electric fields than conventional insulators. Primary or secondary electrons (emitted from the insulator surface) can be deflected by magnetic fields from external sources, the high-current electron beam, the conduction current in the transmission line, or the displacement current in the insulator. These electrons are deflected either toward or away from the insulator surface and this affects the performance of the vacuum insulator. This paper shows the effects of displacement current from short voltage pulses on the performance of high gradient insulators. Generally, vacuum insulator failure is due to surface flashover, initiated by electrons emitted from a triple junction. These electrons strike the insulator surface thus producing secondary electrons, and can lead to a subsequent electron cascade along the surface. The displacement current in the insulator can deflect electrons either toward or away from the insulator surface, and affects the performance of the vacuum insulator when the insulator is subjected to a fast high-voltage pulse. Vacuum insulators composed of alternating layers of metal and dielectric, known as high-gradient insulators (HGIs), have been shown to withstand higher electric fields than conventional insulators. HGIs, being tolerant of the direct view of high-current electron and ion beams, and having desirable RF properties for accelerators, are a key enabling technology for the dielectric-wall accelerators (DWA) being developed at Lawrence Livermore National Laboratory (LLNL). Characteristically, insulator surface breakdown thresholds go up as the applied voltage pulse width decreases. To attain the highest accelerating gradient in the DWA, short accelerating voltage pulses are only applied locally, along the HGI accelerator tube, in sync with the charged particle bunch, and the effects of

  9. Fasting and sampling time affect liver gene expression of high-fat diet-fed mice.

    PubMed

    Lee, C Y

    2010-05-01

    Several physiological and biological variables are known to affect peroxisome proliferator-activated receptor (PPAR)-α-dependent signaling pathway and plasma biochemical profiles. However, less is known about the effect of these variables on high-fat diet-fed mice. In a 5-week study, C57BL/6 mice were divided into control (C) and high-fat diet-fed (H) groups, whereby before dissection, each group was subdivided into non-fasted (nC and nH) and a 15-h fasted mice (fC and fH) killed in the early light cycle, and a 15-h fasted mice (eC and eH) killed in the late phase of the light cycle. Liver and blood from the vena cava were collected. Non-fasted nC and nH mice have a marginal difference in their body weight gain, whereas significant differences were found for fasted mice. In nH mice, PPAR-α, acyl-CoA oxidase and insulin-like growth factor-binding protein expressions were significantly elevated, in contrast to fatty acid synthase (Fasn), stearoyl CoA-desaturase (SCD)-1, and elongase (ELOVL)-6 expressions. Fasn was profoundly induced in fH mice, while decreased sterol regulatory-binding protein-1 and SCD-1 were found only in eH mice. Different from the gene expression profiles, plasma total cholesterol level of the eH mice was higher than controls, whereas nH mice have increased plasma non-esterified fatty acids. Only glucose level of the fH mice was higher than that observed for controls. Results showed that fasting and sampling time have significantly affected liver gene expression and plasma biochemical indices of the high-fat diet-treated mice. An overlook in these aspects can cause serious discrepancies in the experimental data and their interpretations.

  10. 0.6-3.2 μm supercontinuum generation in a step-index germania-core fiber using a 4.4 kW peak-power pump laser.

    PubMed

    Yang, Linyong; Zhang, Bin; Yin, Ke; Yao, Jinmei; Liu, Guangchen; Hou, Jing

    2016-06-13

    An ultra-broadband supercontinuum was generated in a short piece of step-index germania-core fiber using a fiber laser with a peak power of 4.4 kW. The pure germania core made this fiber capable of propagating light towards the desirable mid-infrared region. The spectral broadening characteristics towards the mid-infrared region under different lengths of germania-core fiber were investigated using pump pulses of 4.4 kW and 1.1 ns at 1550 nm. The large nonlinear refractive index of germania and the small core size of germania-core fiber produced a nonlinear coefficient as high as 11.8 (W km)-1 at 1550 nm, which was beneficial for supercontinuum generation. The pump wavelength was located in the anomalous dispersion regime and close to the zero dispersion wavelength of this germania-core fiber, 1.426 μm. Eventually, an ultra-broadband supercontinuum source with a spectrum spanning from 0.6 to 3.2 μm was obtained and had a total output power of 350 mW at an optimized germania-core fiber length of 0.8 m. This work is the first demonstration, to the best of our knowledge, of a germania-core fiber-based ultra-broadband supercontinuum source that spans from the visible region to the mid-infrared region.

  11. High-performance rechargeable batteries with fast solid-state ion conductors

    DOEpatents

    Farmer, Joseph C.

    2017-06-27

    A high-performance rechargeable battery using ultra-fast ion conductors. In one embodiment the rechargeable battery apparatus includes an enclosure, a first electrode operatively connected to the enclosure, a second electrode operatively connected to the enclosure, a nanomaterial in the enclosure, and a heat transfer unit.

  12. High Bandwidth Rotary Fast Tool Servos and a Hybrid Rotary/Linear Electromagnetic Actuator

    SciTech Connect

    Montesanti, Richard Clement

    2005-09-01

    This thesis describes the development of two high bandwidth short-stroke rotary fast tool servos and the hybrid rotary/linear electromagnetic actuator developed for one of them. Design insights, trade-o® methodologies, and analytical tools are developed for precision mechanical systems, power and signal electronic systems, control systems, normal-stress electromagnetic actuators, and the dynamics of the combined systems.

  13. Ultra-Fast Boriding in High-Temperature Materials Processing Industries

    SciTech Connect

    2008-12-01

    This factsheet describes a research project whose main objective is to further develop, optimize, scale-up, and commercialize an ultra-fast boriding (also referred to as “boronizing”) process that can provide much higher energy efficiency, productivity, and near-zero emissions in many of the high-temperature materials processing industries.

  14. Graphene/GaSe-Nanosheet Hybrid: Towards High Gain and Fast Photoresponse

    PubMed Central

    Lu, Rongtao; Liu, Jianwei; Luo, Hongfu; Chikan, Viktor; Wu, Judy Z.

    2016-01-01

    While high photoconductive gain has been recently achieved in graphene-based hybrid phototransistors using semiconductor two-dimensional transition/post-transition metal dichalcogenides or quantum dots sensitizers, obtaining fast photoresponse simutaneously remains a challenge that must be addressed for practical applications. In this paper we report a graphene/GaSe nanosheets hybrid photodetector, in which GaSe nanosheets provide a favorable geometric link to graphene conductive layer through van Der Waals force. After a vacuum annealing process, a high gain in exceeding 107 has been obtained simitaneously with a dynamic response time of around 10 ms for both light on and off. We attribute the high performance to the elimination of possible deep charge traps, most probably at the graphene/GaSe nanosheets interface. This result demonstrates high photoconductive gain and fast photoresponse can be achieved simultaneously and a clean interface is the key to the high performance of these hybrid devices. PMID:26776942

  15. Fast neural network surrogates for very high dimensional physics-based models in computational oceanography.

    PubMed

    van der Merwe, Rudolph; Leen, Todd K; Lu, Zhengdong; Frolov, Sergey; Baptista, Antonio M

    2007-05-01

    We present neural network surrogates that provide extremely fast and accurate emulation of a large-scale circulation model for the coupled Columbia River, its estuary and near ocean regions. The circulation model has O(10(7)) degrees of freedom, is highly nonlinear and is driven by ocean, atmospheric and river influences at its boundaries. The surrogates provide accurate emulation of the full circulation code and run over 1000 times faster. Such fast dynamic surrogates will enable significant advances in ensemble forecasts in oceanography and weather.

  16. A fast chopper for the Fermilab High Intensity Neutrino Source (HINS)

    SciTech Connect

    Madrak, R.; Wildman, D.; Dymokde-Bradshaw, A.; Hares, J.; Kellett, P.

    2008-10-01

    A fast chopper capable of kicking single 2.5 MeV H-bunches spaced at 325 MHz, at rates greater than 50 MHz is needed for the Fermilab High Intensity Neutrino Source (HINS) [1]. Four 1.2 kV fast pulsers, designed and manufactured by Kentech Instruments Ltd., will drive a 0.5 m long meander made from a copper plated ceramic composite. Test results showing pulses from the first 1.2 kV pulser and meander results will be presented.

  17. A highly scalable massively parallel fast marching method for the Eikonal equation

    NASA Astrophysics Data System (ADS)

    Yang, Jianming; Stern, Frederick

    2017-03-01

    The fast marching method is a widely used numerical method for solving the Eikonal equation arising from a variety of scientific and engineering fields. It is long deemed inherently sequential and an efficient parallel algorithm applicable to large-scale practical applications is not available in the literature. In this study, we present a highly scalable massively parallel implementation of the fast marching method using a domain decomposition approach. Central to this algorithm is a novel restarted narrow band approach that coordinates the frequency of communications and the amount of computations extra to a sequential run for achieving an unprecedented parallel performance. Within each restart, the narrow band fast marching method is executed; simple synchronous local exchanges and global reductions are adopted for communicating updated data in the overlapping regions between neighboring subdomains and getting the latest front status, respectively. The independence of front characteristics is exploited through special data structures and augmented status tags to extract the masked parallelism within the fast marching method. The efficiency, flexibility, and applicability of the parallel algorithm are demonstrated through several examples. These problems are extensively tested on six grids with up to 1 billion points using different numbers of processes ranging from 1 to 65536. Remarkable parallel speedups are achieved using tens of thousands of processes. Detailed pseudo-codes for both the sequential and parallel algorithms are provided to illustrate the simplicity of the parallel implementation and its similarity to the sequential narrow band fast marching algorithm.

  18. Fasting and high-fat diet alter histone deacetylase expression in the medial hypothalamus.

    PubMed

    Funato, Hiromasa; Oda, Satoko; Yokofujita, Junko; Igarashi, Hiroaki; Kuroda, Masaru

    2011-04-15

    Increasing attention is now being given to the epigenetic regulation of animal and human behaviors including the stress response and drug addiction. Epigenetic factors also influence feeding behavior and metabolic phenotypes, such as obesity and insulin sensitivity. In response to fasting and high-fat diets, the medial hypothalamus changes the expression of neuropeptides regulating feeding, metabolism, and reproductive behaviors. Histone deacetylases (HDACs) are involved in the epigenetic control of gene expression and alter behavior in response to a variety of environmental factors. Here, we examined the expression of HDAC family members in the medial hypothalamus of mice in response to either fasting or a high-fat diet. In response to fasting, HDAC3 and -4 expression levels increased while HDAC10 and -11 levels decreased. Four weeks on a high-fat diet resulted in the increased expression of HDAC5 and -8. Moreover, fasting decreased the number of acetylated histone H3- and acetylated histone H4-positive cells in the ventrolateral subdivision of the ventromedial hypothalamus. Therefore, HDACs may be implicated in altered gene expression profiles in the medial hypothalamus under different metabolic states.

  19. Fasting and High-Fat Diet Alter Histone Deacetylase Expression in the Medial Hypothalamus

    PubMed Central

    Funato, Hiromasa; Oda, Satoko; Yokofujita, Junko; Igarashi, Hiroaki; Kuroda, Masaru

    2011-01-01

    Increasing attention is now being given to the epigenetic regulation of animal and human behaviors including the stress response and drug addiction. Epigenetic factors also influence feeding behavior and metabolic phenotypes, such as obesity and insulin sensitivity. In response to fasting and high-fat diets, the medial hypothalamus changes the expression of neuropeptides regulating feeding, metabolism, and reproductive behaviors. Histone deacetylases (HDACs) are involved in the epigenetic control of gene expression and alter behavior in response to a variety of environmental factors. Here, we examined the expression of HDAC family members in the medial hypothalamus of mice in response to either fasting or a high-fat diet. In response to fasting, HDAC3 and −4 expression levels increased while HDAC10 and −11 levels decreased. Four weeks on a high-fat diet resulted in the increased expression of HDAC5 and −8. Moreover, fasting decreased the number of acetylated histone H3- and acetylated histone H4-positive cells in the ventrolateral subdivision of the ventromedial hypothalamus. Therefore, HDACs may be implicated in altered gene expression profiles in the medial hypothalamus under different metabolic states. PMID:21526203

  20. Effect of recovery intensity on peak power output and the development of heat strain during intermittent sprint exercise while under heat stress.

    PubMed

    Maxwell, Neil S; Castle, Paul C; Spencer, Matt

    2008-09-01

    This study compared two intensities of active recovery on intermittent sprint exercise performance and the development of heat strain in hot, humid conditions. Eight male game players completed four Cycling Intermittent Sprint Protocols (CISP) consisting of twenty 2-min periods, each including 10-s passive rest, 5-s maximal sprint against a resistance of 7.5% body mass and 105-s active recovery. The CISP was performed in mean (S.D.) temperate conditions with active recovery intensities of 50% V(O)(2peak) (TEMP50) and 35% V(O)(2peak)(TEMP35) and in hot, humid [35.2 (0.4) degrees C, 80.4 (2.1)% RH] conditions with the same intensities (HOT50 and HOT35, respectively) in a randomised, counterbalanced order. Heat strain (physiological strain index (PSI)) was calculated from rectal temperature and heart rate. All subjects completed the CISP (20 sprints) in TEMP50 and TEMP35. The mean number of sprints completed for HOT50 and HOT35 was 13 (3) and 17 (2), respectively; both of which were lower than TEMP50 and TEMP35 (P<0.01) and different between hot conditions. Reductions in peak power output (PPO) occurred in the TEMP50 and HOT50 by sprint 8 (P<0.05), but in HOT35 a reduction was delayed until sprint 13 (P<0.05). The rate of PSI increase was faster in HOT50 than TEMP50 and HOT35, but peak PSI was not different. By lowering the recovery intensity, one component of the PSI (heart rate) was reduced and intermittent sprint exercise performance was maintained for longer in the heat.

  1. Problematic issues of air protection during thermal processes related to the energetic uses of sewage sludge and other waste. Case study: Co-combustion in peaking power plant.

    PubMed

    Hroncová, Emília; Ladomerský, Juraj; Musil, Juraj

    2017-08-19

    Currently, it is necessary to deal with issues related to the emissions as there is a constantly increasing interest in combusting sludge from sewage treatment plants in the boilers for wood. An analysis of the energetic importance of the combustion of sewage sludge has already been carried out, but the effects of various treatments of the sludge are not always clear, e.g. composting and subsequent combustion to the air pollution. Investments in other thermal processes of energetic utilisation of sewage sludge and organic waste are not always successfully implemented. The objective of this paper is to point out some problematic cases for acceptance of thermal processes related to energetic use of waste in terms of the air protection. The other aim is to mention the experience with solutions of such issues in Slovakia. There are mentioned first results of the operational validation experiments during the energy generation in circulating fluidized bed boiler in peaking power plant (Power 110MW) with the addition of the so-called alternative fuel based on wood and sewage sludge to the main fuel - black coal (anthracite). And there has already been achieved the highest share of 12.4%w. (dry matter) of sewage sludge in form of compost in blend with black coal, which is technologically viable. Moreover analyzed the problems of the authorization and operation of the co-combustion of sewage sludge and of combustion of products of various kinds of pyrolysis waste - pyrolysis gas and pyrolysis oil are analyzed. Copyright © 2017 Elsevier Ltd. All rights reserved.

  2. Cognitive control exertion leads to reductions in peak power output and [Formula: see text] as well as increased perceived exertion on a graded exercise test to exhaustion.

    PubMed

    Zering, Jennifer C; Brown, Denver M Y; Graham, Jeffrey D; Bray, Steven R

    2017-09-01

    We investigated effects of a brief (10.5 min) cognitively demanding task on graded exercise test performance. Untrained, university students (N = 15) completed two graded exercise tests in counterbalanced, randomised order. One test was preceded by restful viewing of a documentary video (control); the other by a stop-signal task. Cardiorespiratory functions and perceived exertion were monitored during exercise. Peak power output (W) was lower following the stop-signal task (M = 240.03, SD = 53.37) compared to control (M = 246.03, SD = 52.60), P = 0.002, ηP(2) = 0.493, as was [Formula: see text] (P = 0.042, Cohen's d = 0.55). Perceived exertion was significantly higher at 50% (d = 0.77) and 75% (d = 0.83) of iso-time following the cognitive task (Ps ≤ 0.01). Results are consistent with research showing negative carryover effects of cognitively demanding tasks on whole-body endurance performance. Results also support the psychobiological model of exercise as performance of the cognitive task did not affect perceived exertion when exercise task demands were lower, but lead to greater perceived exertion and earlier withdrawal of effort at higher levels of exercise task demand. Findings have implications for understanding psychological determinants of exercise performance and conditions that may lead to underestimation of [Formula: see text].

  3. Impairment of 40-km time-trial performance but not peak power output with external iliac kinking: a case study in a world-class cyclist.

    PubMed

    Lamberts, Robert P; Mann, T N; Rietjens, Gerard J; Tijdink, Hendrik H

    2014-07-01

    Iliac blood-flow restrictions causing painful and "powerless" legs are often attributed to overtraining and may develop for some time before being correctly diagnosed. In the current study, differences between actual performance parameters and performance parameters predicted from the Lamberts and Lambert Submaximal Cycle Test (LSCT) were studied in a world-class cyclist with bilateral kinking of the external iliac artery before and after surgery. Two performance-testing sessions, including a peak-power-output (PPO) test and a 40-km time trial (TT) were conducted before surgery, while 1 testing session was conducted after the surgery. Actual vs LSCT-predicted performance parameters in the world-class cyclists were compared with 82 symptom-free trained to elite male cyclists. No differences were found between actual and LSCT-predicted PPO before and after surgical intervention. However, there were differences between actual and LSCT-predicted 40-km TT time in the tests performed before the surgery (2:51and 2:55 min:s, respectively). These differences were no longer apparent in the postsurgery 40-km TT (2 s). This finding suggests that iliac blood-flow restrictions seem to mainly impair endurance performance rather than peak cycling performance. A standard PPO test without brachial ankle blood-pressure measurements might not be able to reflect iliac blood-flow restrictions. Differences between actual and LSCT-predicted 40-km TT time may assist in earlier referral to a cardiovascular specialist and result in earlier detection of iliac blood-flow restrictions.

  4. Recent Developments in High-Harmonic Fast Wave Physics in NSTX

    SciTech Connect

    B.P. LeBlanc, R.E. Bell, P. Bonoli, R. Harvey, W.W. Heidbrink, J.C. Hosea, S.M. Kaye, D. Liu, R. Maingi, S.S. Medley, M. Ono, M. Podestà, C.K. Phillips, P.M. Ryan, A.L. Roquemore, G. Taylor, J.R. Wilson and the NSTX Team

    2010-10-06

    Understanding the interaction between ion cyclotron range of frequency (ICRF) fast waves and the fast-ions created by neutral beam injection (NBI) is critical for future devices such as ITER, which rely on a combination ICRF and NBI. Experiments in NSTX which use 30 MHz High-Harmonic Fast-Wave (HHFW) ICRF and NBI heating show a competition between electron heating via Landau damping and transit-time magnetic pumping, and radio-frequency wave acceleration of NBI generated fast ions. Understanding and mitigating some of the power loss mechanisms outside the last closed flux surface (LCFS) has resulted in improved HHFW heating inside the LCFS. Nevertheless a significant fraction of the HHFW power is diverted away from the enclosed plasma. Part of this power is observed locally on the divertor. Experimental observations point toward the radio-frequency (RF) excitation of surface waves, which disperse wave power outside the LCFS, as a leading loss mechanism. Lithium coatings lower the density at the antenna, thereby moving the critical density for perpendicular fast-wave propagation away from the antenna and surrounding material surfaces. Visible and infrared imaging reveal flows of RF power along open field lines into the divertor region. In L-mode -- low average NBI power -- conditions, the fast-ion D-alpha (FIDA) diagnostic measures a near doubling and broadening of the density profile of the upper energetic level of the fast ions concurrent with the presence of HHFW power launched with k// =-8m-1. We are able to heat NBI-induced H-mode plasmas with HHFW. The captured power is expected to be split between absorption by the electrons and absorption by the fast ions, based on TORIC calculation. In the case discussed here the Te increases over the whole profile when ~2MW of HHFW power with antenna k// =13m-1 is applied after the H-mode transition.. But somewhat unexpectedly fast-ion diagnostics do not observe a change between the HHFW heated NBI discharge and the

  5. A modification to the fast decoupled power flow for networks with high R/X ratios

    SciTech Connect

    Rajicic, D.; Bose, A.

    1988-05-01

    For solving power flow problems, the Fast Decoupled Method is probably the most popular because of its efficiency. Its reliability for most power systems is very high but it does have difficulties in convergence for systems with high ratios of branch resistance to reactance. Modifications, that retain the advantages of this method but can handle high r/x ratios, are of great interest and certain compensation techniques have been used for this purpose. Both the series and parallel compensation techniques, however, give mixed results and a new modification is presented here that performed better on several test systems. These test results show that this modified method not only converges very well for systems with high r/x ratios but is only slightly less efficient than the Fast Decoupled Method for systems with normal ratios.

  6. Development and fabrication of a fast recovery, high voltage power diode

    NASA Technical Reports Server (NTRS)

    Berman, A. H.; Balodis, V.; Duffin, J. J.; Gaugh, C.; Kkaratnicki, H. M.; Troutman, G.

    1981-01-01

    The use of positive bevels for P-I-N mesa structures to achieve high voltages is described. The technique of glass passivation for mesa structures is described. The utilization of high energy radiation to control the lifetime of carriers in silicon is reported as a means to achieve fast recovery times. Characterization data is reported and is in agreement with design concepts developed for power diodes.

  7. Fast, high temperature and thermolabile GC--MS in supersonic molecular beams

    NASA Astrophysics Data System (ADS)

    Dagan, Shai; Amirav, Aviv

    1994-05-01

    This work describes and evaluates the coupling of a fast gas chromatograph (GC) based on a short column and high carrier gas flow rate to a supersonic molecular beam mass spectrometer (MS). A 50 cm long megabore column serves for fast GC separation and connects the injector to the supersonic nozzle source. Sampling is achieved with a conventional syringe based splitless sample injection. The injector contains no septum and is open to the atmosphere. The linear velocity of the carrier gas is controlled by a by-pass (make-up) gas flow introduced after the column and prior to the supersonic nozzle. The supersonic expansion serves as a jet separator and the skimmed supersonic molecular beam (SMB) is highly enriched with the heavier organic molecules. The supersonic molecular beam constituents are ionized either by electron impact (EI) or hyperthermal surface ionization (HSI) and mass analyzed. A 1 s fast GC--MS of four aromatic molecules in methanol is demonstrated and some fundamental aspects of fast GC--MS with time limit constraints are outlined. The flow control (programming) of the speed of analysis is shown and the analysis of thermolabile and relatively non-volatile molecules is demonstrated and discussed. The tail-free, fast GC--MS of several mixtures is shown and peak tailing of caffeine is compared with that of conventional GC--MS. The improvement of the peak shapes with the SMB--MS is analyzed with the respect to the elimination of thermal vacuum chamber background. The extrapolated minimum detected amount was about 400 ag of anthracence-d10, with an elution time which was shorter than 2s. Repetitive injections could be performed within less than 10 s. The fast GC--MS in SMB seems to be ideal for fast target compound analysis even in real world, complex mixtures. The few seconds GC--MS separation and quantification of lead (as tetraethyllead) in gasoline, caffeine in coffee, and codeine in a drug is demonstrated. Controlled HSI selectivity is demonstrated in

  8. The ATLAS Fast Tracker and Tracking at the High-Luminosity LHC

    NASA Astrophysics Data System (ADS)

    Ilic, N.

    2017-02-01

    The increase in centre-of-mass energy and luminosity of the Large Hadron Collider makes controlling trigger rates with high efficiency challenging. The ATLAS Fast TracKer is a hardware processor built to reconstruct tracks at a rate of up to 100 kHz and provide them to the high level trigger. The tracker reconstructs tracks by matching incoming detector hits with pre-defined track patterns stored in associative memory on custom ASICs. Inner detector hits are fitted to these track patterns using modern FPGAs. This proceeding describe the electronics system used for the massive parallelization performed by the Fast TracKer. An overview of the installation, commissioning and running of the system is given. The ATLAS upgrades planned to enable tracking at the High-Luminosity Large Hadron Collider are also discussed.

  9. Post flight operation of a high peak power neodymium YAG laser aboard the G-449 payload flown on Space Shuttle Columbia mission 61-C

    NASA Technical Reports Server (NTRS)

    Muckerheide, M. C.

    1992-01-01

    The Nd Yag laser flown on board the G-449 payload completed its postflight testing successfully. There was no indication that the laser had undergone any electronic or optical component failure. A postflight video was taken immediately following the return of the payload to the laboratory. Early anticipation of vibration and temperature changes contributed to the successful operation of the laser. Photographic material resulting from post flight videotape are presented. NASA safety reviews and recommendations supplied the insights which helped contribute to the successful operation of the Nd Yag laser. The safety review data is part of the technical presentation and gives some insight into why the system survived the severe environment of temperature and vibration during the flight of Space Shuttle 61-C.

  10. Fish oil decreases hepatic lipogenic genes in rats fasted and refed on a high fructose diet.

    PubMed

    de Castro, Gabriela S; Cardoso, João Felipe R; Calder, Philip C; Jordão, Alceu A; Vannucchi, Helio

    2015-03-05

    Fasting and then refeeding on a high-carbohydrate diet increases serum and hepatic triacylglycerol (TAG) concentrations compared to standard diets. Fructose is a lipogenic monosaccharide which stimulates de novo fatty acid synthesis. Omega-3 (n-3) fatty acids stimulate hepatic β-oxidation, partitioning fatty acids away from TAG synthesis. This study investigated whether dietary n-3 fatty acids from fish oil (FO) improve the hepatic lipid metabolic response seen in rats fasted and then refed on a high-fructose diet. During the post-prandial (fed) period, rats fed a FO rich diet showed an increase in hepatic peroxisome proliferator-activated receptor α (PPAR-α) gene expression and decreased expression of carbohydrate responsive element binding protein (ChREBP), fatty acid synthase (FAS) and microsomal triglyceride transfer protein (MTTP). Feeding a FO rich diet for 7 days prior to 48 h of fasting resulted in lower hepatic TAG, lower PPAR-α expression and maintenance of hepatic n-3 fatty acid content. Refeeding on a high fructose diet promoted an increase in hepatic and serum TAG and in hepatic PPAR-α, ChREBP and MTTP expression. FO did not prevent the increase in serum and hepatic TAG after fructose refeeding, but did decrease hepatic expression of lipogenic genes and increased the n-3 fatty acid content of the liver. n-3 Fatty acids can modify some components of the hepatic lipid metabolic response to later feeding with a high fructose diet.

  11. Fish Oil Decreases Hepatic Lipogenic Genes in Rats Fasted and Refed on a High Fructose Diet

    PubMed Central

    de Castro, Gabriela S.; Cardoso, João Felipe R.; Calder, Philip C.; Jordão, Alceu A.; Vannucchi, Helio

    2015-01-01

    Fasting and then refeeding on a high-carbohydrate diet increases serum and hepatic triacylglycerol (TAG) concentrations compared to standard diets. Fructose is a lipogenic monosaccharide which stimulates de novo fatty acid synthesis. Omega-3 (n-3) fatty acids stimulate hepatic β-oxidation, partitioning fatty acids away from TAG synthesis. This study investigated whether dietary n-3 fatty acids from fish oil (FO) improve the hepatic lipid metabolic response seen in rats fasted and then refed on a high-fructose diet. During the post-prandial (fed) period, rats fed a FO rich diet showed an increase in hepatic peroxisome proliferator-activated receptor α (PPAR-α) gene expression and decreased expression of carbohydrate responsive element binding protein (ChREBP), fatty acid synthase (FAS) and microsomal triglyceride transfer protein (MTTP). Feeding a FO rich diet for 7 days prior to 48 h of fasting resulted in lower hepatic TAG, lower PPAR-α expression and maintenance of hepatic n-3 fatty acid content. Refeeding on a high fructose diet promoted an increase in hepatic and serum TAG and in hepatic PPAR-α, ChREBP and MTTP expression. FO did not prevent the increase in serum and hepatic TAG after fructose refeeding, but did decrease hepatic expression of lipogenic genes and increased the n-3 fatty acid content of the liver. n-3 Fatty acids can modify some components of the hepatic lipid metabolic response to later feeding with a high fructose diet. PMID:25751821

  12. Fast Batch Production of High-Quality Graphene Films in a Sealed Thermal Molecular Movement System.

    PubMed

    Xu, Jianbao; Hu, Junxiong; Li, Qi; Wang, Rubing; Li, Weiwei; Guo, Yufen; Zhu, Yongbo; Liu, Fengkui; Ullah, Zaka; Dong, Guocai; Zeng, Zhongming; Liu, Liwei

    2017-07-01

    Chemical vapor deposition (CVD) growth of high-quality graphene has emerged as the most promising technique in terms of its integrated manufacturing. However, there lacks a controllable growth method for producing high-quality and a large-quantity graphene films, simultaneously, at a fast growth rate, regardless of roll-to-roll (R2R) or batch-to-batch (B2B) methods. Here, a stationary-atmospheric-pressure CVD (SAPCVD) system based on thermal molecular movement, which enables fast B2B growth of continuous and uniform graphene films on tens of stacked Cu(111) foils, with a growth rate of 1.5 µm s(-1) , is demonstrated. The monolayer graphene of batch production is found to nucleate from arrays of well-aligned domains, and the films possess few defects and exhibit high carrier mobility up to 6944 cm(2) V(-1) s(-1) at room temperature. The results indicate that the SAPCVD system combined with single-domain Cu(111) substrates makes it possible to realize fast batch-growth of high-quality graphene films, which opens up enormous opportunities to use this unique 2D material for industrial device applications. © 2017 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

  13. Advances in high-harmonic fast wave physics in the National Spherical Torus Experiment

    SciTech Connect

    Taylor, G.; Bell, R. E.; Hosea, J. C.; LeBlanc, B. P.; Phillips, C. K.; Podesta, M.; Valeo, E. J.; Wilson, J. R.; Ahn, J-W.; Chen, G.; Green, D. L.; Jaeger, E. F.; Maingi, R.; Ryan, P. M.; Wilgen, J. B.; Heidbrink, W. W.; Liu, D.; Bonoli, P. T.; Brecht, T.; Choi, M.

    2010-05-15

    Improved core high-harmonic fast wave (HHFW) heating at longer wavelengths and during start-up and plasma current ramp-up has now been obtained by lowering the edge density with lithium wall conditioning, thereby moving the critical density for perpendicular fast-wave propagation away from the vessel wall. Lithium conditioning allowed significant HHFW core electron heating of deuterium neutral beam injection (NBI) fuelled H-mode plasmas to be observed for the first time. Large edge localized modes were observed immediately after the termination of rf power. Visible and infrared camera images show that fast wave interactions can deposit considerable rf energy on the outboard divertor. HHFW-generated parametric decay instabilities were observed to heat ions in the plasma edge and may be the cause for a measured drag on edge toroidal rotation during HHFW heating. A significant enhancement in neutron rate and fast-ion profile was measured in NBI-fuelled plasmas when HHFW heating was applied.

  14. Advances in High-harmonic Fast Wave Physics in the National Spherical Torus Experiment

    SciTech Connect

    Taylor, G; Hosea, J C; LeBlanc, B P; Phillips, C K; Podesta, M; Valeo, E J; Wilson, J R; Ahn, J -W; Chen, G; Green, D L; Jaeger, E F; Maingi, R; Ryan, P M; Wilgen, J B; Heidbrink, W W; Liu, D; Bonoli, P T; Brecht, T; Choi, M

    2009-12-01

    Improved core high-harmonic fast wave (HHFW) heating at longer wavelengths and during start-up and plasma current ramp-up, has now been obtained by lowering the edge density with lithium wall conditioning, thereby moving the critical density for perpendicular fast-wave propagation away from the vessel wall. Lithium conditioning allowed significant HHFW core electron heating of deuterium neutral beam injection (NBI) fuelled H-mode plasmas to be observed for the first time. Large edge localized modes were observed immediately after the termination of rf power. Visible and infrared camera images show that fast wave interactions can deposit considerable rf energy on the outboard divertor. HHFW-generated parametric decay instabilities were observed to heat ions in the plasma edge and may be the cause for a measured drag on edge toroidal rotation during HHFW heating. A significant enhancement in neutron rate and fast-ion profile were measured in NBI-fuelled plasmas when HHFW heating was applied. __________________________________________________

  15. A fast high-order method to calculate wakefields in an electron beam

    NASA Astrophysics Data System (ADS)

    Qiang, Ji; Mitchell, Chad; Ryne, Robert D.

    2012-08-01

    In this paper, we report on a high-order fast method to numerically calculate wakefields in an electron beam given a wake function model. This method is based on a Newton-Cotes quadrature rule for integral approximation and an FFT method for discrete summation that results in an O(N log(N)) computational cost, where N is the number of grid points. Using the Simpson quadrature rule with an accuracy of O(h4), where h is the grid size, we present numerical calculation of the wakefields from a resonator wake function model and from a one-dimensional coherent synchrotron radiation (CSR) wake model. Besides the fast speed and high numerical accuracy, the calculation using the direct line density instead of the first derivative of the line density avoids numerical filtering of the electron density function for computing the CSR wakefield.

  16. A fast high-order method to calculate wakefield forces in an electron beam

    SciTech Connect

    Qiang, Ji; Mitchell, Chad; Ryne, Robert D.

    2012-03-22

    In this paper we report on a high-order fast method to numerically calculate wakefield forces in an electron beam given a wake function model. This method is based on a Newton-Cotes quadrature rule for integral approximation and an FFT method for discrete summation that results in an O(Nlog(N)) computational cost, where N is the number of grid points. Using the Simpson quadrature rule with an accuracy of O(h4), where h is the grid size, we present numerical calculation of the wakefields from a resonator wake function model and from a one-dimensional coherent synchrotron radiation (CSR) wake model. Besides the fast speed and high numerical accuracy, the calculation using the direct line density instead of the first derivative of the line density avoids numerical filtering of the electron density function for computing the CSR wakefield force. I. INTRODUCTION

  17. Superconducting gamma and fast-neutron spectrometers with high energy resolution

    DOEpatents

    Friedrich, Stephan; , Niedermayr, Thomas R.; Labov, Simon E.

    2008-11-04

    Superconducting Gamma-ray and fast-neutron spectrometers with very high energy resolution operated at very low temperatures are provided. The sensor consists of a bulk absorber and a superconducting thermometer weakly coupled to a cold reservoir, and determines the energy of the incident particle from the rise in temperature upon absorption. A superconducting film operated at the transition between its superconducting and its normal state is used as the thermometer, and sensor operation at reservoir temperatures around 0.1 K reduces thermal fluctuations and thus enables very high energy resolution. Depending on the choice of absorber material, the spectrometer can be configured either as a Gamma-spectrometer or as a fast-neutron spectrometer.

  18. Cuprophilic interactions in highly luminescent dicopper(i)-NHC-picolyl complexes - fast phosphorescence or TADF?

    PubMed

    Nitsch, Jörn; Lacemon, Frederick; Lorbach, Andreas; Eichhorn, Antonius; Cisnetti, Federico; Steffen, Andreas

    2016-02-18

    This case study on a series of monomeric, dimeric and polymeric Cu(I) chlorido NHC-picolyl complexes shows that cuprophilic interactions can ensure strong spin-orbit coupling for fast (reverse)intersystem-crossing T1 ↔ S1 and T1 → S0, and therefore can serve as a design motif for the construction of highly efficient Cu(I)-based TADF or T1 emitters.

  19. Collimated Propagation of Fast Electron Beams Accelerated by High-Contrast Laser Pulses in Highly Resistive Shocked Carbon.

    PubMed

    Vaisseau, X; Morace, A; Touati, M; Nakatsutsumi, M; Baton, S D; Hulin, S; Nicolaï, Ph; Nuter, R; Batani, D; Beg, F N; Breil, J; Fedosejevs, R; Feugeas, J-L; Forestier-Colleoni, P; Fourment, C; Fujioka, S; Giuffrida, L; Kerr, S; McLean, H S; Sawada, H; Tikhonchuk, V T; Santos, J J

    2017-05-19

    Collimated transport of ultrahigh intensity electron current was observed in cold and in laser-shocked vitreous carbon, in agreement with simulation predictions. The fast electron beams were created by coupling high-intensity and high-contrast laser pulses onto copper-coated cones drilled into the carbon samples. The guiding mechanism-observed only for times before the shock breakout at the inner cone tip-is due to self-generated resistive magnetic fields of ∼0.5-1  kT arising from the intense currents of fast electrons in vitreous carbon, by virtue of its specific high resistivity over the range of explored background temperatures. The spatial distribution of the electron beams, injected through the samples at different stages of compression, was characterized by side-on imaging of hard x-ray fluorescence.

  20. Collimated Propagation of Fast Electron Beams Accelerated by High-Contrast Laser Pulses in Highly Resistive Shocked Carbon

    NASA Astrophysics Data System (ADS)

    Vaisseau, X.; Morace, A.; Touati, M.; Nakatsutsumi, M.; Baton, S. D.; Hulin, S.; Nicolaï, Ph.; Nuter, R.; Batani, D.; Beg, F. N.; Breil, J.; Fedosejevs, R.; Feugeas, J.-L.; Forestier-Colleoni, P.; Fourment, C.; Fujioka, S.; Giuffrida, L.; Kerr, S.; McLean, H. S.; Sawada, H.; Tikhonchuk, V. T.; Santos, J. J.

    2017-05-01

    Collimated transport of ultrahigh intensity electron current was observed in cold and in laser-shocked vitreous carbon, in agreement with simulation predictions. The fast electron beams were created by coupling high-intensity and high-contrast laser pulses onto copper-coated cones drilled into the carbon samples. The guiding mechanism—observed only for times before the shock breakout at the inner cone tip—is due to self-generated resistive magnetic fields of ˜0.5 - 1 kT arising from the intense currents of fast electrons in vitreous carbon, by virtue of its specific high resistivity over the range of explored background temperatures. The spatial distribution of the electron beams, injected through the samples at different stages of compression, was characterized by side-on imaging of hard x-ray fluorescence.

  1. High-definition velocity-space tomography of fast-ion dynamics

    NASA Astrophysics Data System (ADS)

    Salewski, M.; Geiger, B.; Jacobsen, A. S.; Hansen, P. C.; Heidbrink, W. W.; Korsholm, S. B.; Leipold, F.; Madsen, J.; Moseev, D.; Nielsen, S. K.; Nocente, M.; Odstrčil, T.; Rasmussen, J.; Stagner, L.; Stejner, M.; Weiland, M.; the ASDEX Upgrade Team

    2016-10-01

    Velocity-space tomography of the fast-ion distribution function in a fusion plasma is usually a photon-starved tomography method due to limited optical access and signal-to-noise ratio of fast-ion D α (FIDA) spectroscopy as well as the strive for high-resolution images. In high-definition tomography, prior information makes up for this lack of data. We restrict the target velocity space through the measured absence of FIDA light, impose phase-space densities to be non-negative, and encode the known geometry of neutral beam injection (NBI) sources. We further use a numerical simulation as prior information to reconstruct where in velocity space the measurements and the simulation disagree. This alternative approach is demonstrated for four-view as well as for two-view FIDA measurements. The high-definition tomography tools allow us to study fast ions in sawtoothing plasmas and the formation of NBI peaks at full, half and one-third energy by time-resolved tomographic movies.

  2. BeamDyn: a high-fidelity wind turbine blade solver in the FAST modular framework

    DOE PAGES

    Wang, Qi; Sprague, Michael A.; Jonkman, Jason; ...

    2017-03-14

    Here, this paper presents a numerical implementation of the geometrically exact beam theory based on the Legendre-spectral-finite-element (LSFE) method. The displacement-based geometrically exact beam theory is presented, and the special treatment of three-dimensional rotation parameters is reviewed. An LSFE is a high-order finite element with nodes located at the Gauss-Legendre-Lobatto points. These elements can be an order of magnitude more computationally efficient than low-order finite elements for a given accuracy level. The new module, BeamDyn, is implemented in the FAST modularization framework for dynamic simulation of highly flexible composite-material wind turbine blades within the FAST aeroelastic engineering model. The frameworkmore » allows for fully interactive simulations of turbine blades in operating conditions. Numerical examples are provided to validate BeamDyn and examine the LSFE performance as well as the coupling algorithm in the FAST modularization framework. BeamDyn can also be used as a stand-alone high-fidelity beam tool.« less

  3. Optimal Local Searching for Fast and Robust Textureless 3D Object Tracking in Highly Cluttered Backgrounds.

    PubMed

    Seo, Byung-Kuk; Park, Jong-Il; Hinterstoisser, Stefan; Ilic, Slobodan

    2013-06-13

    Edge-based tracking is a fast and plausible approach for textureless 3D object tracking, but its robustness is still very challenging in highly cluttered backgrounds due to numerous local minima. To overcome this problem, we propose a novel method for fast and robust textureless 3D object tracking in highly cluttered backgrounds. The proposed method is based on optimal local searching of 3D-2D correspondences between a known 3D object model and 2D scene edges in an image with heavy background clutter. In our searching scheme, searching regions are partitioned into three levels (interior, contour, and exterior) with respect to the previous object region, and confident searching directions are determined by evaluating candidates of correspondences on their region levels; thus, the correspondences are searched among likely candidates in only the confident directions instead of searching through all candidates. To ensure the confident searching direction, we also adopt the region appearance, which is efficiently modeled on a newly defined local space (called a searching bundle). Experimental results and performance evaluations demonstrate that our method fully supports fast and robust textureless 3D object tracking even in highly cluttered backgrounds.

  4. Optimal local searching for fast and robust textureless 3D object tracking in highly cluttered backgrounds.

    PubMed

    Seo, Byung-Kuk; Park, Hanhoon; Park, Jong-Il; Hinterstoisser, Stefan; Ilic, Slobodan

    2014-01-01

    Edge-based tracking is a fast and plausible approach for textureless 3D object tracking, but its robustness is still very challenging in highly cluttered backgrounds due to numerous local minima. To overcome this problem, we propose a novel method for fast and robust textureless 3D object tracking in highly cluttered backgrounds. The proposed method is based on optimal local searching of 3D-2D correspondences between a known 3D object model and 2D scene edges in an image with heavy background clutter. In our searching scheme, searching regions are partitioned into three levels (interior, contour, and exterior) with respect to the previous object region, and confident searching directions are determined by evaluating candidates of correspondences on their region levels; thus, the correspondences are searched among likely candidates in only the confident directions instead of searching through all candidates. To ensure the confident searching direction, we also adopt the region appearance, which is efficiently modeled on a newly defined local space (called a searching bundle). Experimental results and performance evaluations demonstrate that our method fully supports fast and robust textureless 3D object tracking even in highly cluttered backgrounds.

  5. Fast and highly specific DNA-based multiplex detection on a solid support.

    PubMed

    Barišić, Ivan; Kamleithner, Verena; Schönthaler, Silvia; Wiesinger-Mayr, Herbert

    2015-01-01

    Highly specific and fast multiplex detection methods are essential to conduct reasonable DNA-based diagnostics and are especially important to characterise infectious diseases. More than 1000 genetic targets such as antibiotic resistance genes, virulence factors and phylogenetic markers have to be identified as fast as possible to facilitate the correct treatment of a patient. In the present work, we developed a novel ligation-based DNA probe concept that was combined with the microarray technology and used it for the detection of bacterial pathogens. The novel linear chain (LNC) probes identified all tested species correctly within 1 h based on their 16S rRNA gene in a 25-multiplex reaction. Genomic DNA was used directly as template in the ligation reaction identifying as little as 10(7) cells without any pre-amplification. The high specificity was further demonstrated characterising a single nucleotide polymorphism leading to no false positive fluorescence signals of the untargeted single nucleotide polymorphism (SNP) variants. In comparison to conventional microarray probes, the sensitivity of the novel LNC3 probes was higher by a factor of 10 or more. In summary, we present a fast, simple, highly specific and sensitive multiplex detection method adaptable for a wide range of applications.

  6. Stroke education program of act FAST for junior high school students and their parents.

    PubMed

    Amano, Tatsuo; Yokota, Chiaki; Sakamoto, Yuki; Shigehatake, Yuya; Inoue, Yasuteru; Ishigami, Akiko; Hagihara, Takaaki; Tomii, Yasuhiro; Miyashita, Fumio; Toyoda, Kazunori; Minematsu, Kazuo

    2014-01-01

    We produced a stroke education program using the FAST (facial droop, arm weakness, speech disturbance, time to call an ambulance) mnemonic. The aim of this study is to examine efficacy of our education program for junior high school students and their parents. One hundred ninety students of 3 junior high schools (aged 12-13 years) and their parents were enrolled. Students received a 45-minute lesson of stroke enlightenment using the FAST mnemonic. Enlightenment items, such as a magnet poster, were distributed. Parents were educated indirectly from their child. Surveys of stroke knowledge were examined at baseline, immediately after the lesson, and at 3 months after the lesson. For the students, correct answers at 3 months were significantly higher than those at baseline in questions of facial palsy (98% versus 33%), speech disturbance (98% versus 54%), numbness on one side (64% versus 42%), weakness on one side (80% versus 51%), calling an ambulance (88% versus 60%), alcohol drinking (85% versus 65%), smoking (70% versus 43%), dyslipidemia (58% versus 46%), hyperglycemia (59% versus 48%), and obesity (47% versus 23%). At 3 months, the parents answered more correctly questions of facial palsy (93% versus 66%), calling an ambulance (95% versus 88%), and alcohol drinking (65% versus 51%) than at baseline. At 3 months, 96% of students and 78% of parents answered the FAST mnemonic correctly. Our stroke education program improved stroke knowledge, especially the FAST message, for junior high school students and their parents. Copyright © 2014 National Stroke Association. Published by Elsevier Inc. All rights reserved.

  7. Design Considerations of Fast Kicker Systems for High Intensity Proton Accelerators

    SciTech Connect

    Zhang, W; Sandberg, J; Parson, W M; Walstrom, P; Murray, M M; Cook, E; Hartouni, E

    2001-06-12

    In this paper, we discuss the specific issues related to the design of the Fast Kicker Systems for high intensity proton accelerators. To address these issues in the preliminary design stage can be critical since the fast kicker systems affect the machine lattice structure and overall design parameters. Main topics include system architecture, design strategy, beam current coupling, grounding, end user cost vs. system cost, reliability, redundancy and flexibility. Operating experience with the Alternating Gradient Synchrotron injection and extraction kicker systems at Brookhaven National Laboratory and their future upgrade is presented. Additionally, new conceptual designs of the extraction kicker for the Spallation Neutron Source at Oak Ridge and the Advanced Hydrotest Facility at Los Alamos are discussed.

  8. Modeling of high harmonic fast wave current drive on EAST tokamak

    SciTech Connect

    Li, J. C.; Gong, X. Y. Li, F. Y.; Dong, J. Q.; Gao, Q. D.; Zhang, N.

    2015-10-15

    High harmonic fast waves (HHFW) are among the candidates for non-inductive current drive (CD), which is essential for long-pulse or steady-state operation of tokamaks. Current driven with HHFW in EAST tokamak plasmas is numerically studied. The HHFW CD efficiency is found to increase non-monotonically with the wave frequency, and this phenomenon is attributed to the multi-pass absorption of HHFW. The sensitivity of CD efficiency to the value of the parallel refraction index of the launched wave is confirmed. The quasilinear effects, assessed as significant in HHFW current drive with the GENRAY/CQL3D package, cause a significant increase in CD efficiency as RF power is increased, which is very different from helicon current drive. Simulations for a range of toroidal dc electric fields, in combination with a range of fast wave powers, are also presented and indicate that the presence of the DC field can also enhance the CD efficiency.

  9. High-Resolution Fast-Neutron Spectrometry for Arms Control and Treaty Verification

    SciTech Connect

    David L. Chichester; James T. Johnson; Edward H. Seabury

    2012-07-01

    Many nondestructive nuclear analysis techniques have been developed to support the measurement needs of arms control and treaty verification, including gross photon and neutron counting, low- and high-resolution gamma spectrometry, time-correlated neutron measurements, and photon and neutron imaging. One notable measurement technique that has not been extensively studied to date for these applications is high-resolution fast-neutron spectrometry (HRFNS). Applied for arms control and treaty verification, HRFNS has the potential to serve as a complimentary measurement approach to these other techniques by providing a means to either qualitatively or quantitatively determine the composition and thickness of non-nuclear materials surrounding neutron-emitting materials. The technique uses the normally-occurring neutrons present in arms control and treaty verification objects of interest as an internal source of neutrons for performing active-interrogation transmission measurements. Most low-Z nuclei of interest for arms control and treaty verification, including 9Be, 12C, 14N, and 16O, possess fast-neutron resonance features in their absorption cross sections in the 0.5- to 5-MeV energy range. Measuring the selective removal of source neutrons over this energy range, assuming for example a fission-spectrum starting distribution, may be used to estimate the stoichiometric composition of intervening materials between the neutron source and detector. At a simpler level, determination of the emitted fast-neutron spectrum may be used for fingerprinting 'known' assemblies for later use in template-matching tests. As with photon spectrometry, automated analysis of fast-neutron spectra may be performed to support decision making and reporting systems protected behind information barriers. This paper will report recent work at Idaho National Laboratory to explore the feasibility of using HRFNS for arms control and treaty verification applications, including simulations and

  10. Advances in High-Harmonic Fast Wave Physics in the National Spherical Torus Experiment

    NASA Astrophysics Data System (ADS)

    Taylor, Gary

    2009-11-01

    Improved core high-harmonic fast wave (HHFW) heating, particularly at longer wavelengths and during low-density start-up and current ramp-up, has now been obtained by lowering the edge density with lithium conditioning, thereby moving the propagation onset away from the vessel wall. Significant core electron heating of deuterium neutral beam injection (NBI) fuelled H-modes has been observed for the first time over a range of launched wavelengths. The observed broadening of the electron heating profile in H-mode relative to L-mode plasmas is consistent with simulations obtained with ray tracing and full wave models. Newly taken camera images indicate that fast wave interactions can deposit considerable RF energy on the outboard divertor plate, especially at longer wavelengths that begin to propagate closer to the vessel walls. Edge power loss can also arise from HHFW-generated parametric decay instabilities that drive ions in the edge onto direct loss orbits that intersect the wall, and may be the cause for an observed drag on edge toroidal rotation in combined HHFW and NBI discharges. Fast-Ion D-alpha emission clearly shows fast-ion profile broadening in the plasma core that is much greater than predicted by Fokker-Planck modeling when HHFW power is applied to NBI-fuelled plasmas, pointing to the need for a full-orbit treatment in the simulation. Large ELMs have been observed immediately following the termination of RF power, whether the power turn off is programmed or due to antenna arcing. RF power has been successfully applied during large ELMs by setting the source reflection coefficient trip levels to relatively high values -- an approach potentially important for ITER ICRF heating. Plans for an HHFW ELM-resilience upgrade will be presented.

  11. Calorie Underestimation When Buying High-Calorie Beverages in Fast-Food Contexts.

    PubMed

    Franckle, Rebecca L; Block, Jason P; Roberto, Christina A

    2016-07-01

    We asked 1877 adults and 1178 adolescents visiting 89 fast-food restaurants in New England in 2010 and 2011 to estimate calories purchased. Calorie underestimation was greater among those purchasing a high-calorie beverage than among those who did not (adults: 324 ±698 vs 102 ±591 calories; adolescents: 360 ±602 vs 198 ±509 calories). This difference remained significant for adults but not adolescents after adjusting for total calories purchased. Purchasing high-calorie beverages may uniquely contribute to calorie underestimation among adults.

  12. Prompting one low-fat, high-fiber selection in a fast-food restaurant.

    PubMed Central

    Wagner, J L; Winett, R A

    1988-01-01

    Evidence increasingly links a high-fat, low-fiber diet to coronary heart disease and certain site cancers, indicating a need for large-scale dietary change. Studies showing the effectiveness of particular procedures in specific settings are important at this point. The present study, using an A-B-A-B design and sales data from computerized cash registers, replicated and extended previous work by showing that inexpensive prompts (i.e., signs and fliers) in a national fast-food restaurant could increase the sales of salads, a low-fat, high-fiber menu selection. Suggestions also are made pertinent to more widespread use of the procedures. PMID:2843493

  13. Investigation of fast nonstationary events with high-speed cinematography with a new drum camera

    NASA Astrophysics Data System (ADS)

    Eisfeld, Fritz

    1993-01-01

    For investigations of fast nonstationary events, e.g., flows, injection jets, etc., the high speed cinematography is particularly suitable, but there are difficulties with 3-dimensional motions. First the paper deals with problems and objectives which arose during the development of a new drum camera that is also suitable for high speed holography. The result is a drum camera for up to 200,000 f/s, also for use with holograms. The camera set-up and first test results are described, and possibilities of further developments are shown.

  14. Wavefront coding for fast, high-resolution light-sheet microscopy (Conference Presentation)

    NASA Astrophysics Data System (ADS)

    Olarte, Omar E.; Licea-Rodriguez, Jacob; Loza-Alvarez, Pablo

    2017-02-01

    Some biological experiments demand the observation of dynamics processes in 3D with high spatiotemporal resolution. The use of wavefront coding to extend the depth-of-field (DOF) of the collection arm of a light-sheet microscope is an interesting alternative for fast 3D imaging. Under this scheme, the 3D features of the sample are captured at high volumetric rates while the light sheet is swept rapidly within the extended DOF. The DOF is extended by coding the pupil function of the imaging lens by using a custom-designed phase mask. A posterior restoration step is required to decode the information of the captured images based on the applied phase mask [1]. This hybrid optical-digital approach is known as wavefront coding (WFC). Previously, we have demonstrated this method for performing fast 3D imaging of biological samples at medium resolution [2]. In this work, we present the extension of this approach for high-resolution microscopes. Under these conditions, the effective DOF of a standard high NA objective is of a few micrometers. Here we demonstrate that by the use of WFC, we can extend the DOF more than one order of magnitude keeping the high-resolution imaging. This is demonstrated for two designed phase masks using Zebrafish and C. elegans samples. [1] Olarte, O.E., Andilla, J., Artigas, D., and Loza-Alvarez, P., "Decoupled Illumination-Detection Microscopy. Selected Optics in Year 2105," in Optics and Photonics news 26, p. 41 (2015). [2] Olarte, O.E., Andilla, J., Artigas, D., and Loza-Alvarez, P., "Decoupled illumination detection in light sheet microscopy for fast volumetric imaging," Optica 2(8), 702 (2015).

  15. Advances in High Harmonic Fast Wave Heating of NSTX H-mode Plasmas

    SciTech Connect

    Ryan, Philip Michael; Ahn, Joonwook; Bell, R. E.; Bonoli, P.; Chen, Guangye; Green, David L; Harvey, R. W.; Hosea, J.; Jaeger, Erwin Frederick; Kaye, S.; LeBlanc, B; Maingi, Rajesh; Phillips, Cynthia; Podesta, M.; Taylor, G.; Wilgen, John B; Wilson, J. R.

    2010-01-01

    High-harmonic fast wave (HHFW) heating and current drive is being developed in NSTX to provide bulk electron heating and q(0) control during non-inductively sustained Hmode plasmas fuelled by deuterium neutral-beam injection (NBI). In addition, it is used to assist the plasma current ramp-up. A major modification to increase the RF power limit was made in 2009; the original end-grounded, single end-powered current straps of the 12- element array were replaced with center-grounded, double end-powered straps. Greater than 3 MW have been coupled into NBI-driven, ELMy H-mode plasmas with this upgraded antenna. Improved core HHFW heating, particularly at longer wavelengths and during low-density start-up and plasma current ramp-up, has been obtained by lowering the edge density with lithium wall conditioning, thereby moving the critical density for fast-wave propagation away from the vessel wall [1]. Significant core electron heating of NBI-fuelled H-modes has been observed for the first time over a range of launched wavelengths and H-modes can be accessed by HHFW alone. Visible and IR camera images of the antenna and divertor indicate that fast wave interactions can deposit considerable RF energy on the outboard divertor plate, especially at longer wavelengths that begin to propagate closer to the vessel walls. Edge power loss can also arise from HHFWgenerated parametric decay instabilities; edge ion heating is observed that is wavelength dependent. During plasmas where HHFW is combined with NBI, there is a significant enhancement in neutron rate, and fast-ion D-alpha (FIDA) emission measurements clearly show broadening of the fast-ion profile in the plasma core. Large edge localized modes (ELMs) have been observed immediately following the termination of RF power, whether the power turn off is programmed or due to antenna arcing. Causality has not been established but new experiments are planned and will be reported. Fast digitization of the reflected power signal

  16. High Voltage, Fast-Switching Module for Active Control of Magnetic Fields and Edge Plasma Currents

    NASA Astrophysics Data System (ADS)

    Ziemba, Timothy; Miller, Kenneth; Prager, James; Slobodov, Ilia

    2016-10-01

    Fast, reliable, real-time control of plasma is critical to the success of magnetic fusion science. High voltage and current supplies are needed to mitigate instabilities in all experiments as well as disruption events in large scale tokamaks for steady-state operation. Silicon carbide (SiC) MOSFETs offer many advantages over IGBTs including lower drive energy requirements, lower conduction and switching losses, and higher switching frequency capabilities; however, these devices are limited to 1.2-1.7 kV devices. As fusion enters the long-pulse and burning plasma eras, efficiency of power switching will be important. Eagle Harbor Technologies (EHT), Inc. developing a high voltage SiC MOSFET module that operates at 10 kV. This switch module utilizes EHT gate drive technology, which has demonstrated the ability to increase SiC MOSFET switching efficiency. The module will allow more rapid development of high voltage switching power supplies at lower cost necessary for the next generation of fast plasma feedback and control. EHT is partnering with the High Beta Tokamak group at Columbia to develop detailed high voltage module specifications, to ensure that the final product meets the needs of the fusion science community.

  17. High-precision and fast computation of Jacobi-Fourier moments for image description.

    PubMed

    Camacho-Bello, C; Toxqui-Quitl, C; Padilla-Vivanco, A; Báez-Rojas, J J

    2014-01-01

    A high-precision and fast algorithm for computation of Jacobi-Fourier moments (JFMs) is presented. A fast recursive method is developed for the radial polynomials that occur in the kernel function of the JFMs. The proposed method is numerically stable and very fast in comparison with the conventional direct method. Moreover, the algorithm is suitable for computation of the JFMs of the highest orders. The JFMs are generic expressions to generate orthogonal moments changing the parameters α and β of Jacobi polynomials. The quality of the description of the proposed method with α and β parameters known is studied. Also, a search is performed of the best parameters, α and β, which significantly improves the quality of the reconstructed image and recognition. Experiments are performed on standard test images with various sets of JFMs to prove the superiority of the proposed method in comparison with the direct method. Furthermore, the proposed method is compared with other existing methods in terms of speed and accuracy.

  18. Fast spectral coherent anti-Stokes Raman scattering microscopy with high-speed tunable picosecond laser.

    PubMed

    Cahyadi, Harsono; Iwatsuka, Junichi; Minamikawa, Takeo; Niioka, Hirohiko; Araki, Tsutomu; Hashimoto, Mamoru

    2013-09-01

    We develop a coherent anti-Stokes Raman scattering (CARS) microscopy system equipped with a tunable picosecond laser for high-speed wavelength scanning. An acousto-optic tunable filter (AOTF) is integrated in the laser cavity to enable wavelength scanning by varying the radio frequency waves applied to the AOTF crystal. An end mirror attached on a piezoelectric actuator and a pair of parallel plates driven by galvanometer motors are also introduced into the cavity to compensate for changes in the cavity length during wavelength scanning to allow synchronization with another picosecond laser. We demonstrate fast spectral imaging of 3T3-L1 adipocytes every 5  cm-1 in the Raman spectral region around 2850  cm-1 with an image acquisition time of 120 ms. We also demonstrate fast switching of Raman shifts between 2100 and 2850  cm-1, corresponding to CD2 symmetric stretching and CH2 symmetric stretching vibrations, respectively. The fast-switching CARS images reveal different locations of recrystallized deuterated and nondeuterated stearic acid.

  19. High-{rho}R Implosions for Fast-Ignition Fuel Assembly

    SciTech Connect

    Zhou, C. D.; Betti, R.; Meyerhofer, D. D.; Theobald, W.; Radha, P. B.; Smalyuk, V. A.; Glebov, V. Yu.; Stoeckl, C.; Anderson, K. S.; Sangster, T. C.; Shvarts, D.; Li, C. K.; Petrasso, R. D.; Frenje, J. A.; Seguin, F. H.

    2007-01-12

    Thick, 40 {mu}m plastic shells filled with 25-35 atm of D{sub 2} or D{sup 3}He were imploded on a low-adiabat ({alpha}{approx_equal}1.3) and with a low-implosion velocity ({approx}2x10{sup 7} cm/s) on the OMEGA laser to generate massive cores of compressed plasma with high areal densities optimal for fast ignition. The targets are driven by 20-kJ relaxation adiabat-shaping laser pulses to keep the inner portion of the shell nearly Fermi degenerate. The measured kinetic energy downshift of proton spectra is in good agreement with the theoretical predictions yielding burn-averaged areal densities of 0.130{+-}0.017 g/cm{sup 2} and peak {rho}R during the burn of about 0.24{+-}0.018 g/cm{sup 2}, the largest {rho}R measured on OMEGA to date. The same implosions with empty plastic shells are expected to reach 1.3 g/cm{sup 2} across the core (i.e., 2{rho}R) enough to stop fast electrons with energies up to 4.5 MeV typical of fast ignition scenarios.

  20. Compact, highly sensitive optical gyros and sensors with fast-light

    NASA Astrophysics Data System (ADS)

    Christensen, Caleb A.; Zavriyev, Anton; Cummings, Malcolm; Beal, A. C.; Lucas, Mark; Lagasse, Michael

    2015-09-01

    Fast-light phenomena can enhance the sensitivity of an optical gyroscope of a given size by several orders of magnitude, and could be applied to other optical sensors as well. MagiQ Technologies has been developing a compact fiber-based fast light Inertial Measurement Unit (IMU) using Stimulated Brillouin Scattering in optical fibers with commercially mature technologies. We will report on our findings, including repeatable fast-light effects in the lab, numerical analysis of noise and stability given realistic optical specs, and methods for optimizing efficiency, size, and reliability with current technologies. The technology could benefit inertial navigation units, gyrocompasses, and stabilization techniques, and could allow high grade IMUs in spacecraft, unmanned aerial vehicles or sensors, where the current size and weight of precision gyros are prohibitive. By using photonic integrated circuits and telecom-grade components along with specialty fibers, we also believe that our design is appropriate for development without further advances in the state of the art of components.

  1. Statin myalgia is not associated with reduced muscle strength, mass or protein turnover in older male volunteers, but is allied with a slowing of time to peak power output, insulin resistance and differential muscle mRNA expression

    PubMed Central

    Mallinson, Joanne E.; Marimuthu, Kanagaraj; Murton, Andrew; Selby, Anna; Smith, Kenneth; Constantin‐Teodosiu, Dumitru; Rennie, Michael J.

    2015-01-01

    ) and fed (≈40 mU l−1 insulin + hyperaminoacidaemia) euglyceamic clamps. Muscle biopsies were taken before and after each clamp. Lean mass, MPS, LPB and strength were not different but work output during the initial three isokinetic contractions was 19% lower (P < 0.05) in statin myalgic subjects due to a delay in time to reach peak power output. Statin myalgic subjects had reduced whole body (P = 0.05) and leg (P < 0.01) glucose disposal, greater abdominal adiposity (P < 0.05) and differential expression of 33 muscle mRNAs (5% false discovery rate (FDR)), six of which, linked to mitochondrial dysfunction and apoptosis, increased at 1% FDR. Statin myalgia was associated with impaired muscle function, increased abdominal adiposity, whole body and leg insulin resistance, and evidence of mitochondrial dysfunction and apoptosis. PMID:25620655

  2. Optimization of Cone Wall Thickness to Reduce High Energy Electron Generation for Fast-Ignition Scheme

    NASA Astrophysics Data System (ADS)

    Kojima, Sadaoki; Zhe, Zhang; Sawada, Hiroshi; Firex Team

    2015-11-01

    In Fast Ignition Inertial Confinement Fusion, optimization of relativistic electron beam (REB) accelerated by a high-intensity laser pulse is critical for the efficient core heating. The high-energy tail of the electron spectrum is generated by the laser interaction with a long-scale-length plasma and does not efficiently couple to a fuel core. In the cone-in-shell scheme, long-scale-length plasmas can be produced inside the cone by the pedestal of a high-intensity laser, radiation heating of the inner cone wall and shock wave from an implosion core. We have investigated a relation between the presence of pre-plasma inside the cone and the REB energy distribution using the Gekko XII and 2kJ-PW LFEX laser at the Institute of Laser Engineering. The condition of an inner cone wall was monitored using VISAR and SOP systems on a cone-in-shell implosion. The generation of the REB was measured with an electron energy analyzer and a hard x-ray spectrometer on a separate shot by injecting the LFEX laser in an imploded target. The result shows the strong correlation between the preheat and high-energy tail generation. Optimization of cone-wall thickness for the fast-ignition will be discussed. This work is supported by NIFS, MEXT/JSPS KAKENHI Grant and JSPS Fellows (Grant Number 14J06592).

  3. High-throughput microplate enzymatic assays for fast sugar and acid quantification in apple and tomato.

    PubMed

    Vermeir, S; Nicolaï, B M; Jans, K; Maes, G; Lammertyn, J

    2007-05-02

    In this article, we report on the use of miniaturized and automated enzymatic assays as an alternative technology for fast sugar and acid quantification in apples and tomatoes. Enzymatic assays for d-glucose, d-fructose, sucrose, D-sorbitol/xylitol, L-malic acid, citric acid, succinic acid, and L-glutamic acid were miniaturized from the standard 3 mL assays in cuvettes into assays of 200 microL or lower in 96 or 384 well microplates. The miniaturization and the automation were achieved with a four channel automatic liquid handling system in order to reduce the dispensing errors and to obtain an increased sample throughput. Performance factors (limit of detection, linearity of calibration curve, and repeatability) of the assays with standard solutions were proven to be satisfactory. The automated and miniaturized assays were validated with high-pressure liquid chromatography (HPLC) analyses for the quantification of sugars and acids in tomato and apple extracts. The high correlation between the two techniques for the different components indicates that the high-throughput microplate enzymatic assays can serve as a fast, reliable, and inexpensive alternative for HPLC as the standard analysis technique in the taste characterization of fruit and vegetables. In addition to the analysis of extracts, the high-throughput microplate enzymatic assays were used for the direct analysis of centrifuged and filtered tomato juice with an additional advantage that the sample preparation time and analysis costs are reduced significantly.

  4. Fast response temperature and humidity sensors for measurements in high Reynolds number flows

    NASA Astrophysics Data System (ADS)

    Fan, Yuyang; Arwatz, Gilad; Vallikivi, Margit; Hultmark, Marcus

    2013-11-01

    Conventional hot/cold wires have been widely used in measuring velocity and temperature in turbulent flows due to their fine resolutions and fast response. However, for very high Reynolds number flows, limitations on the resolution appear. A very high Reynolds number flow is the atmospheric boundary layer. In order to accurately predict the energy balance at the Earth's surface, one needs information about the different turbulent scalar fields, mainly temperature and humidity, which together with velocity, contribute to the turbulent fluxes away from the surface. The nano-scaled thermal anemometry probe (NSTAP) was previously developed at Princeton and has proven to have much higher spatial and temporal resolution than the regular hot wires. Here we introduce new fast-response temperature and humidity sensors that have been developed and tested. These sensors are made in-house using standard MEMS manufacturing techniques, leaving high flexibility in the process for optimization to different conditions. The small dimensions of these novel sensors enable very high spatial resolution while the small thermal mass allows significant improvements in the frequency response. These sensors have shown promising results in acquiring un-biased data of turbulent scalar and vector fields. Supported under ONR Grants N00014-12-1-0875 and N00014-12-1-0962 (program manager Ki-Han Kim).

  5. High-throughput gas chromatography for volatile compounds analysis by fast temperature programming and adsorption chromatography.

    PubMed

    Gras, Ronda; Hua, Yujuan; Luong, Jim

    2017-05-01

    The synergy of combining fast temperature programming capability and adsorption chromatography using fused silica based porous layer open tubular columns to achieve high throughput chromatography for the separation of volatile compounds is presented. A gas chromatograph with built-in fast temperature programming capability and having a fast cool down rate was used as a platform. When these performance features were combined with the high degree of selectivity and strong retention characteristic of porous layer open tubular column technology, volatile compounds such as light hydrocarbons of up to C7 , primary alcohols, and mercaptans can be well separated and analyzed in a matter of minutes. This analytical approach substantially improves sample throughput by at least a factor of ten times when compared to published methodologies. In addition, the use of porous layer open tubular columns advantageously eliminates the need for costly and time-consuming cryogenic gas chromatography required for the separation of highly volatile compounds by partition chromatography with wall coated open tubular column technology. Relative standard deviations of retention time for model compounds such as alkanes from methane to hexane were found to be less than 0.3% (n = 10) and less than 0.5% for area counts for the compounds tested at two levels of concentration by manual injection, namely, 10 and 1000 ppm v/v (n = 10). Difficult separations were accomplished in one single analysis in less than 2 min such as the characterization of 17 components in cracked gas containing alkanes, alkenes, dienes, branched hydrocarbons, and cyclic hydrocarbons. © 2017 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

  6. Interferometric adaptive optics for high-power laser beam correction in fast ignition experiments

    SciTech Connect

    Homoelle, D C; Baker, K L; Patel, P K; Utterback, E; Rushford, M C; Siders, C W; Barty, C J

    2009-10-22

    We present the design for a high-speed adaptive optics system that will be used to achieve the necessary laser pointing and beam-quality performance for initial fast-ignition coupling experiments. This design makes use of a 32 x 32 pixellated MEMS device as the adaptive optic and a two-channel interferometer as the wave-front sensor. We present results from a system testbed that demonstrates improvement of the Strehl ratio from 0.09 to 0.61 and stabilization of beam pointing from {approx}75{micro}rad to <2{micro}rad.

  7. Tests of a Fast Plastic Scintillator for High-Precision Half-Life Measurements

    NASA Astrophysics Data System (ADS)

    Laffoley, A. T.; Dunlop, R.; Finlay, P.; Leach, K. G.; Michetti-Wilson, J.; Rand, E. T.; Svensson, C. E.; Grinyer, G. F.; Thomas, J. C.; Ball, G.; Garnsworthy, A. B.; Hackman, G.; Orce, J. N.; Triambak, S.; Williams, S. J.; Andreoiu, C.; Cross, D.

    2013-03-01

    A fast plastic scintillator detector is evaluated for possible use in an ongoing program of high-precision half-life measurements of short lived β emitters. Using data taken at TRI-UMF's Isotope Separator and Accelerator Facility with a radioactive 26Na beam, a detailed investigation of potential systematic effects with this new detector setup is being performed. The technique will then be applied to other β-decay half-life measurements including the superallowed Fermi β emitters 10C, 14O, and T = 1/2 decay of 15O.

  8. High-frame-rate intensified fast optically shuttered TV cameras with selected imaging applications

    SciTech Connect

    Yates, G.J.; King, N.S.P.

    1994-08-01

    This invited paper focuses on high speed electronic/electro-optic camera development by the Applied Physics Experiments and Imaging Measurements Group (P-15) of Los Alamos National Laboratory`s Physics Division over the last two decades. The evolution of TV and image intensifier sensors and fast readout fast shuttered cameras are discussed. Their use in nuclear, military, and medical imaging applications are presented. Several salient characteristics and anomalies associated with single-pulse and high repetition rate performance of the cameras/sensors are included from earlier studies to emphasize their effects on radiometric accuracy of electronic framing cameras. The Group`s test and evaluation capabilities for characterization of imaging type electro-optic sensors and sensor components including Focal Plane Arrays, gated Image Intensifiers, microchannel plates, and phosphors are discussed. Two new unique facilities, the High Speed Solid State Imager Test Station (HSTS) and the Electron Gun Vacuum Test Chamber (EGTC) arc described. A summary of the Group`s current and developmental camera designs and R&D initiatives are included.

  9. Anomalous fast ion losses at high β on the tokamak fusion test reactor

    SciTech Connect

    Fredrickson, E. D.; Bell, M. G.; Budny, R. V.; Darrow, D. S.; White, R.

    2015-03-15

    This paper describes experiments carried out on the Tokamak Fusion Test Reactor (TFTR) [R. J. Hawryluk et al., Plasma Phys. Controlled Fusion 33, 1509 (1991)] to investigate the dependence of β-limiting disruption characteristics on toroidal field strength. The hard disruptions found at the β-limit in high field plasmas were not found at low field, even for β's 50% higher than the empirical β-limit of β{sub n} ≈ 2 at high field. Comparisons of experimentally measured β's to TRANSP simulations suggest anomalous loss of up to half of the beam fast ions in the highest β, low field shots. The anomalous transport responsible for the fast ion losses may at the same time broaden the pressure profile. Toroidal Alfvén eigenmodes, fishbone instabilities, and Geodesic Acoustic Modes are investigated as possible causes of the enhanced losses. Here, we present the first observations of high frequency fishbones [F. Zonca et al., Nucl. Fusion 49, 085009 (2009)] on TFTR. The interpretation of Axi-symmetric Beam-driven Modes as Geodesic Acoustic Modes and their possible correlation with transport barrier formation are also presented.

  10. Fast access to reduced-resolution subsamples of high-resolution images

    NASA Astrophysics Data System (ADS)

    Isaacson, Joel S.

    1991-08-01

    Frequently, displaying a digital image requires reducing the volume of data contained in a high-resolution image. This reduction can be performed by sub- sampling pixels from the high resolution image. Some examples of systems that need fast access to reduced resolution images are: modern digital prepress production; flight simulators; terrestrial planetary and astronomical imaging systems. On standard workstations, a lower resolution image cannot be read without essentially reading the whole high-resolution image. This paper demonstrates a method that allows fast access to lower scale resolution images. The method has the following characteristics. The proposed storage format greatly lessens the time needed to read a low-resolution image typically by an order of magnitude. The storage format supports efficient reading of multiple scale reduced resolutions. The image file size remains the same as in current formats. No penalty is imposed by using this new format for any operation that uses the image at full resolution. Additionally, an efficient method for rotating images in this format is demonstrated that is many times faster than methods currently employed. The last section gives benchmarks that demonstrate the utility of this format for reading an image at low resolution.

  11. Fast high-throughput screening of temoporfin-loaded liposomal formulations prepared by ethanol injection method.

    PubMed

    Yang, Kewei; Delaney, Joseph T; Schubert, Ulrich S; Fahr, Alfred

    2012-03-01

    A new strategy for fast, convenient high-throughput screening of liposomal formulations was developed, utilizing the automation of the so-called ethanol-injection method. This strategy was illustrated by the preparation and screening of the liposomal formulation library of a potent second-generation photosensitizer, temoporfin. Numerous liposomal formulations were efficiently prepared using a pipetting robot, followed by automated size characterization, using a dynamic light scattering plate reader. Incorporation efficiency of temoporfin and zeta potential were also detected in selected cases. To optimize the formulation, different parameters were investigated, including lipid types, lipid concentration in injected ethanol, ratio of ethanol to aqueous solution, ratio of drug to lipid, and the addition of functional phospholipid. Step-by-step small liposomes were prepared with high incorporation efficiency. At last, an optimized formulation was obtained for each lipid in the following condition: 36.4 mg·mL(-1) lipid, 13.1 mg·mL(-1) mPEG(2000)-DSPE, and 1:4 ethanol:buffer ratio. These liposomes were unilamellar spheres, with a diameter of approximately 50 nm, and were very stable for over 20 weeks. The results illustrate this approach to be promising for fast high-throughput screening of liposomal formulations.

  12. High-contrast and fast electrochromic switching enabled by plasmonics (Conference Presentation)

    NASA Astrophysics Data System (ADS)

    Talin, A. Alec

    2016-09-01

    With vibrant colors and simple, room-temperature processing methods, electrochromic polymers have long attracted attention as active materials for flexible, low-power consuming devices such as smart windows and displays. However, despite their many advantages, slow switching speed and complexity of combining several separate polymers to achieve full-color gamut has limited electrochromic materials to niche applications. Here we exploit the enhanced light-matter interaction associated with the deep-subwavelength mode confinement of surface plasmon polaritons propagating in metallic nanoslit arrays coated with ultra-thin electrochromic polymers to build a novel configuration for achieving high-contrast and fast electrochromic switching. The switchable configuration retains the short temporal charge-diffusion characteristics of thin electrochromic films while maintaining the high optical-contrast associated with thicker electrochromic coatings. We further demonstrate that by controlling the pitch of the nanoslit arrays, it is possible to achieve a full-color response with high-contrast and fast switching-speeds while relying on just one electrochromic polymer.

  13. Adaptive AFM scan speed control for high aspect ratio fast structure tracking.

    PubMed

    Ahmad, Ahmad; Schuh, Andreas; Rangelow, Ivo W

    2014-10-01

    Improved imaging rates in Atomic Force Microscopes (AFM) are of high interest for disciplines such as life sciences and failure analysis of semiconductor wafers, where the sample topology shows high aspect ratios. Also, fast imaging is necessary to cover a large surface under investigation in reasonable times. Since AFMs are composed of mechanical components, they are associated with comparably low resonance frequencies that undermine the effort to increase the acquisition rates. In particular, high and steep structures are difficult to follow, which causes the cantilever to temporarily loose contact to or crash into the sample. Here, we report on a novel approach that does not affect the scanner dynamics, but adapts the lateral scanning speed of the scanner. The controller monitors the control error signal and, only when necessary, decreases the scan speed to allow the z-piezo more time to react to changes in the sample's topography. In this case, the overall imaging rate can be significantly increased, because a general scan speed trade-off decision is not needed and smooth areas are scanned fast. In contrast to methods trying to increase the z-piezo bandwidth, our method is a comparably simple approach that can be easily adapted to standard systems.

  14. Anomalous fast ion losses at high β on the tokamak fusion test reactor

    NASA Astrophysics Data System (ADS)

    Fredrickson, E. D.; Bell, M. G.; Budny, R. V.; Darrow, D. S.; White, R.

    2015-03-01

    This paper describes experiments carried out on the Tokamak Fusion Test Reactor (TFTR) [R. J. Hawryluk et al., Plasma Phys. Controlled Fusion 33, 1509 (1991)] to investigate the dependence of β-limiting disruption characteristics on toroidal field strength. The hard disruptions found at the β-limit in high field plasmas were not found at low field, even for β's 50% higher than the empirical β-limit of βn ≈ 2 at high field. Comparisons of experimentally measured β's to TRANSP simulations suggest anomalous loss of up to half of the beam fast ions in the highest β, low field shots. The anomalous transport responsible for the fast ion losses may at the same time broaden the pressure profile. Toroidal Alfvén eigenmodes, fishbone instabilities, and Geodesic Acoustic Modes are investigated as possible causes of the enhanced losses. Here, we present the first observations of high frequency fishbones [F. Zonca et al., Nucl. Fusion 49, 085009 (2009)] on TFTR. The interpretation of Axi-symmetric Beam-driven Modes as Geodesic Acoustic Modes and their possible correlation with transport barrier formation are also presented.

  15. Adaptive AFM scan speed control for high aspect ratio fast structure tracking

    SciTech Connect

    Ahmad, Ahmad; Schuh, Andreas; Rangelow, Ivo W.

    2014-10-15

    Improved imaging rates in Atomic Force Microscopes (AFM) are of high interest for disciplines such as life sciences and failure analysis of semiconductor wafers, where the sample topology shows high aspect ratios. Also, fast imaging is necessary to cover a large surface under investigation in reasonable times. Since AFMs are composed of mechanical components, they are associated with comparably low resonance frequencies that undermine the effort to increase the acquisition rates. In particular, high and steep structures are difficult to follow, which causes the cantilever to temporarily loose contact to or crash into the sample. Here, we report on a novel approach that does not affect the scanner dynamics, but adapts the lateral scanning speed of the scanner. The controller monitors the control error signal and, only when necessary, decreases the scan speed to allow the z-piezo more time to react to changes in the sample's topography. In this case, the overall imaging rate can be significantly increased, because a general scan speed trade-off decision is not needed and smooth areas are scanned fast. In contrast to methods trying to increase the z-piezo bandwidth, our method is a comparably simple approach that can be easily adapted to standard systems.

  16. Using high-resolution global mantle circulation models to understand fast seismic velocity anomalies

    NASA Astrophysics Data System (ADS)

    Webb, P. J.; Davies, J.; Davies, R.

    2011-12-01

    Mantle circulation models (MCMs) incorporate plate motion history into a standard mantle convection model. They are an important tool for studying the link between plate tectonics and Earth's interior. Such models are used to predict temperature fields throughout the mantle, which can be compared to seismic tomography, a present day snapshot of Earth's mantle. Assuming a mantle primarily driven by thermal convection we relate regions of colder than average mantle to regions of faster than average seismic velocity. Traditionally, mantle circulation models have used 120 million years of plate motion history as their surface velocity boundary condition. Such models can reconcile observed large-scale fast seismic velocity anomalies in regions of major plate convergence, to depths of around 1300 km. Recent advances allow for high-resolution mantle circulation models with up to 300 million years of plate motion history. When combined with higher resolution tomographic studies we are now able to study the influence of subduction on mantle heterogeneity structure, in greater detail. In this study we present results from a suite of mantle circulation models across a wide parameter space. By comparing the predicted temperature fields to seismic tomography we gain an understanding of which parameters affect the location and magnitude of subduction related anomalies. We also quantify the effect of using mineral physics data to convert modelled temperature fields to seismic velocity. In the simplest cases, we can accurately predict the larger regional scale, mid-mantle fast seismic velocity anomalies, including remnants of the Farallon slab beneath North America and the Tethys oceans below South East Asia. However, the more realistic high-resolution studies allow us to investigate other areas of interest, including more localised aspects of Tethyan subduction associated with the closure of smaller ocean basins. We also examine the model predictions for subducted material in

  17. Metabolic compensation during high energy output in fasting, lactating grey seals (Halichoerus grypus): metabolic ceilings revisited.

    PubMed Central

    Mellish, J A; Iverson, S J; Bowen, W D

    2000-01-01

    Lactation is the most energetically expensive period for female mammals and is associated with some of the highest sustained metabolic rates (SusMR) in vertebrates (reported as total energy throughput). Females typically deal with this energy demand by increasing food intake and the structure of the alimentary tract may act as the central constraint to ceilings on SusMR at about seven times resting or standard metabolic rate (SMR). However, demands of lactation may also be met by using a form of metabolic compensation such as reducing locomotor activities or entering torpor. In some phocid seals, cetaceans and bears, females fast throughout lactation and thus cannot offset the high energetic costs of lactation through increased food intake. We demonstrate that fasting grey seal females sustain, for several weeks, one of the highest total daily energy expenditures (DEE; 7.4 x SMR) reported in mammals, while progressively reducing maintenance metabolic expenditures during lactation through means not explained by reduction in lean body mass or behavioural changes. Simultaneously, the energy-exported in milk is progressively increased, associated with increased lipoprotein lipase activity in the mammary gland, resulting in greater offspring growth. Our results suggest that females use compensatory mechanisms to help meet the extraordinary energetic costs of lactation. Additionally, although the concepts of SusMR and ceilings on total DEE may be somewhat different in fasting lactating species, our data on phocid seals demonstrate that metabolic ceilings on milk energy output, in general, are not constrained by the same kind of peripheral limitations as are other energy-consuming tissues. In phocid seals, the high ceilings on DEE during lactation, coupled with metabolic compensation, are undoubtedly important factors enabling shortened lactation. PMID:10902691

  18. Fast blood flow visualization of high-resolution laser speckle imaging data using graphics processing unit.

    PubMed

    Liu, Shusen; Li, Pengcheng; Luo, Qingming

    2008-09-15

    Laser speckle contrast analysis (LASCA) is a non-invasive, full-field optical technique that produces two-dimensional map of blood flow in biological tissue by analyzing speckle images captured by CCD camera. Due to the heavy computation required for speckle contrast analysis, video frame rate visualization of blood flow which is essentially important for medical usage is hardly achieved for the high-resolution image data by using the CPU (Central Processing Unit) of an ordinary PC (Personal Computer). In this paper, we introduced GPU (Graphics Processing Unit) into our data processing framework of laser speckle contrast imaging to achieve fast and high-resolution blood flow visualization on PCs by exploiting the high floating-point processing power of commodity graphics hardware. By using GPU, a 12-60 fold performance enhancement is obtained in comparison to the optimized CPU implementations.

  19. Application of high-precision matching about multisensor in fast stereo imaging

    NASA Astrophysics Data System (ADS)

    Zhang, Huijing; Zhou, Mei; Wu, Haohao; Zhang, Dandan

    2015-10-01

    High precision matching of linear array multi-sensor is the key to ensure fast stereo imaging. This paper has presented the general principle of active and passive imaging sensor, designed a high precision matching calibration system of linear array multi-sensor based on large-diameter collimator combined with assisted laser light source, and put forward an optical axis parallelism calibration technology suitable for linear array active and passive imaging sensor. This technology makes use of image acquisition system to obtain spot center, in order to match multi-linear array laser receive and transmit optical axes. At the same time, this paper uses linear visible light sources to extract the optical axis of the laser, then completes the parallelism calibration between lasers receive and transmit optical axes of multi-linear array sensors and active and passive optical axis. The matching relationship between the visible pixel and laser radar detecting element can be obtained when using this technique to calibrate the active and passive imaging sensor. And this relationship is applied to the fast stereo imaging experiment of active and passive imaging sensor and gained good imaging effect.

  20. A fast and high performance multiple data integration algorithm for identifying human disease genes

    PubMed Central

    2015-01-01

    Background Integrating multiple data sources is indispensable in improving disease gene identification. It is not only due to the fact that disease genes associated with similar genetic diseases tend to lie close with each other in various biological networks, but also due to the fact that gene-disease associations are complex. Although various algorithms have been proposed to identify disease genes, their prediction performances and the computational time still should be further improved. Results In this study, we propose a fast and high performance multiple data integration algorithm for identifying human disease genes. A posterior probability of each candidate gene associated with individual diseases is calculated by using a Bayesian analysis method and a binary logistic regression model. Two prior probability estimation strategies and two feature vector construction methods are developed to test the performance of the proposed algorithm. Conclusions The proposed algorithm is not only generated predictions with high AUC scores, but also runs very fast. When only a single PPI network is employed, the AUC score is 0.769 by using F2 as feature vectors. The average running time for each leave-one-out experiment is only around 1.5 seconds. When three biological networks are integrated, the AUC score using F3 as feature vectors increases to 0.830, and the average running time for each leave-one-out experiment takes only about 12.54 seconds. It is better than many existing algorithms. PMID:26399620

  1. Development of a commercial line of high-performance fast-steering mirrors

    NASA Astrophysics Data System (ADS)

    Berta, Albert; Hedding, Larry R.; Hoffman, Charlie; Messaros, Michael

    1999-07-01

    Fast-steering mirrors, called FSMs, for short, and sometimes referred to as fine-steering or tip-tilt mirrors, are primarily two-axis devices originally developed for a variety of demanding air and space applications for line-of- sight pointing and beam stabilization. Ball Aerospace has been engaged in the design and development of fast-steering mirrors since 1983. In 1994, Ball began employing lessons learned from these one-of-a-kind custom units to develop a commercial line of low cost (< $DLR50 K), high- performance mirrors to serve the general optics community. This paper first provides a brief overview of our overall FSM development history and some successful applications. Next, our commercial FSMs are described along with performance specifications and test results. Parameters of interest discussed include bandwidth, acceleration, accuracy, reliability, and types of mirror substrates. Test results on two models of commercial 3-in mirrors demonstrating accuracies of < 1 (mu) rad, life and reliability > 108 cycles, and the ability to endure high-level random vibration are presented.

  2. A fast radiative transfer model for the assimilation of water vapor radiances from the Kalpana very high resolution radiometer

    NASA Astrophysics Data System (ADS)

    Singh, Randhir; Rayer, Peter; Saunders, Roger; Migliorini, Stefano; Brugge, Roger; O'Neill, Alan

    2009-04-01

    A fast radiative transfer model (RTM) to compute emitted infrared radiances for a very high resolution radiometer (VHRR), onboard the operational Indian geostationary satellite Kalpana has been developed and verified. This work is a step towards the assimilation of Kalpana water vapor (WV) radiances into numerical weather prediction models. The fast RTM uses a regression-based approach to parameterize channel-specific convolved level to space transmittances. A comparison between the fast RTM and the line-by-line RTM demonstrated that the fast RTM can simulate line-by-line radiances for the Kalpana WV channel to an accuracy better than the instrument noise, while offering more rapid radiance calculations. A comparison of clear sky radiances of the Kalpana WV channel with the ECMWF model first guess radiances is also presented, aiming to demonstrate the fast RTM performance with the real observations. In order to assimilate the radiances from Kalpana, a simple scheme for bias correction has been suggested.

  3. Unique charge distribution in surface loops confers high velocity on the fast motor protein Chara myosin.

    PubMed

    Ito, Kohji; Yamaguchi, Yukie; Yanase, Kenji; Ichikawa, Yousuke; Yamamoto, Keiichi

    2009-12-22

    Most myosins have a positively charged loop 2 with a cluster of lysine residues that bind to the negatively charged N-terminal segment of actin. However, the net charge of loop 2 of very fast Chara myosin is zero and there is no lysine cluster in it. In contrast, Chara myosin has a highly positively charged loop 3. To elucidate the role of these unique surface loops of Chara myosin in its high velocity and high actin-activated ATPase activity, we have undertaken mutational analysis using recombinant Chara myosin motor domain. It was found that net positive charge in loop 3 affected V(max) and K(app) of actin activated ATPase activity, while it affected the velocity only slightly. The net positive charge in loop 2 affected K(app) and the velocity, although it did not affect V(max). Our results suggested that Chara myosin has evolved to have highly positively charged loop 3 for its high ATPase activity and have less positively charged loop 2 for its high velocity. Since high positive charge in loop 3 and low positive charge in loop 2 seem to be one of the reasons for Chara myosin's high velocity, we manipulated charge contents in loops 2 and 3 of Dictyostelium myosin (class II). Removing positive charge from loop 2 and adding positive charge to loop 3 of Dictyostelium myosin made its velocity higher than that of the wild type, suggesting that the charge strategy in loops 2 and 3 is widely applicable.

  4. FAST implementation in Bangladesh: high frequency of unsuspected tuberculosis justifies challenges of scale-up.

    PubMed

    Nathavitharana, R R; Daru, P; Barrera, A E; Mostofa Kamal, S M; Islam, S; Ul-Alam, M; Sultana, R; Rahman, M; Hossain, Md S; Lederer, P; Hurwitz, S; Chakraborty, K; Kak, N; Tierney, D B; Nardell, E

    2017-09-01

    National Institute of Diseases of the Chest and Hospital, Dhaka; Bangladesh Institute of Research and Rehabilitation in Diabetes, Endocrine and Metabolic Disorders, Dhaka; and Chittagong Chest Disease Hospital, Chittagong, Bangladesh. To present operational data and discuss the challenges of implementing FAST (Find cases Actively, Separate safely and Treat effectively) as a tuberculosis (TB) transmission control strategy. FAST was implemented sequentially at three hospitals. Using Xpert® MTB/RIF, 733/6028 (12.2%, 95%CI 11.4-13.0) patients were diagnosed with unsuspected TB. Patients with a history of TB who were admitted with other lung diseases had more than twice the odds of being diagnosed with unsuspected TB as those with no history of TB (OR 2.6, 95%CI 2.2-3.0, P < 0.001). Unsuspected multidrug-resistant TB (MDR-TB) was diagnosed in 89/1415 patients (6.3%, 95%CI 5.1-7.7). Patients with unsuspected TB had nearly five times the odds of being diagnosed with MDR-TB than those admitted with a known TB diagnosis (OR 4.9, 95%CI 3.1-7.6, P < 0.001). Implementation challenges include staff shortages, diagnostic failure, supply-chain issues and reliance on external funding. FAST implementation revealed a high frequency of unsuspected TB in hospitalized patients in Bangladesh. Patients with a previous history of TB have an increased risk of being diagnosed with unsuspected TB. Ensuring financial resources, stakeholder engagement and laboratory capacity are important for sustainability and scalability.

  5. A DEMO relevant fast wave current drive high harmonic antenna exploiting the high impedance technique

    NASA Astrophysics Data System (ADS)

    Milanesio, D.; Maggiora, R.

    2015-12-01

    Ion Cyclotron (IC) antennas are routinely adopted in most of the existing nuclear fusion experiments, even though their main goal, i.e. to couple high power to the plasma (MW), is often limited by rather severe drawbacks due to high fields on the antenna itself and on the unmatched part of the feeding lines. In addition to the well exploited auxiliary ion heating during the start-up phase, some non-ohmic current drive (CD) at the IC range of frequencies may be explored in view of the DEMO reactor. In this work, we suggest and describe a compact high frequency DEMO relevant antenna, based on the high impedance surfaces concept. High-impedance surfaces are periodic metallic structures (patches) usually displaced on top of a dielectric substrate and grounded by means of vertical posts embedded inside the dielectric, in a mushroom-like shape. These structures present a high impedance, within a given frequency band, such that the image currents are in-phase with the currents of the antenna itself, thus determining a significant efficiency increase. After a general introduction on the properties of high impedance surfaces, we analyze, by means of numerical codes, a dielectric based and a full metal solution optimized to be tested and benchmarked on the FTU experiment fed with generators at 433MHz.

  6. A DEMO relevant fast wave current drive high harmonic antenna exploiting the high impedance technique

    SciTech Connect

    Milanesio, D. Maggiora, R.

    2015-12-10

    Ion Cyclotron (IC) antennas are routinely adopted in most of the existing nuclear fusion experiments, even though their main goal, i.e. to couple high power to the plasma (MW), is often limited by rather severe drawbacks due to high fields on the antenna itself and on the unmatched part of the feeding lines. In addition to the well exploited auxiliary ion heating during the start-up phase, some non-ohmic current drive (CD) at the IC range of frequencies may be explored in view of the DEMO reactor. In this work, we suggest and describe a compact high frequency DEMO relevant antenna, based on the high impedance surfaces concept. High-impedance surfaces are periodic metallic structures (patches) usually displaced on top of a dielectric substrate and grounded by means of vertical posts embedded inside the dielectric, in a mushroom-like shape. These structures present a high impedance, within a given frequency band, such that the image currents are in-phase with the currents of the antenna itself, thus determining a significant efficiency increase. After a general introduction on the properties of high impedance surfaces, we analyze, by means of numerical codes, a dielectric based and a full metal solution optimized to be tested and benchmarked on the FTU experiment fed with generators at 433MHz.

  7. Thermal X-ray emission from massive, fast rotating, highly magnetized white dwarfs

    NASA Astrophysics Data System (ADS)

    Cáceres, D. L.; de Carvalho, S. M.; Coelho, J. G.; de Lima, R. C. R.; Rueda, Jorge A.

    2017-03-01

    There is solid observational evidence on the existence of massive, M ∼ 1 M⊙, highly magnetized white dwarfs (WDs) with surface magnetic fields up to B ∼ 109 G. We show that, if in addition to these features, the star is fast rotating, it can become a rotation-powered pulsar-like WD and emit detectable high-energy radiation. We infer the values of the structure parameters (mass, radius, moment of inertia), magnetic field, rotation period and spin-down rates of a WD pulsar death-line. We show that WDs above the death-line emit blackbody radiation in the soft X-ray band via the magnetic polar cap heating by back flowing pair-created particle bombardment and discuss as an example the X-ray emission of soft gamma-repeaters and anomalous X-ray pulsars within the WD model.

  8. Fast acquisition of high-resolution 2D NMR spectroscopy in inhomogeneous magnetic fields

    NASA Astrophysics Data System (ADS)

    Lin, Liangjie; Wei, Zhiliang; Zeng, Qing; Yang, Jian; Lin, Yanqin; Chen, Zhong

    2016-05-01

    High-resolution nuclear magnetic resonance (NMR) spectroscopy plays an important role in chemical and biological analyses. In this study, we combine the J-coupling coherence transfer module with the echo-train acquisition technique for fast acquisition of high-resolution 2D NMR spectra in magnetic fields with unknown spatial variations. The proposed method shows satisfactory performance on a 5 mM ethyl 3-bromopropionate sample, under a 5-kHz (10 ppm at 11.7 T) B0 inhomogeneous field, as well as under varying degrees of pulse-flip-angle deviations. Moreover, a simulative ex situ NMR measurement is also conducted to show the effectiveness of the proposed pulse sequence.

  9. Electric eels use high-voltage to track fast-moving prey

    PubMed Central

    Catania, Kenneth C.

    2015-01-01

    Electric eels (Electrophorus electricus) are legendary for their ability to incapacitate fish, humans, and horses with hundreds of volts of electricity. The function of this output as a weapon has been obvious for centuries but its potential role for electroreception has been overlooked. Here it is shown that electric eels use high-voltage simultaneously as a weapon and for precise and rapid electrolocation of fast-moving prey and conductors. Their speed, accuracy, and high-frequency pulse rate are reminiscent of bats using a ‘terminal feeding buzz' to track insects. Eel's exhibit ‘sensory conflict' when mechanosensory and electrosensory cues are separated, striking first toward mechanosensory cues and later toward conductors. Strikes initiated in the absence of conductors are aborted. In addition to providing new insights into the evolution of strongly electric fish and showing electric eels to be far more sophisticated than previously described, these findings reveal a trait with markedly dichotomous functions. PMID:26485580

  10. Electric eels use high-voltage to track fast-moving prey.

    PubMed

    Catania, Kenneth C

    2015-10-20

    Electric eels (Electrophorus electricus) are legendary for their ability to incapacitate fish, humans, and horses with hundreds of volts of electricity. The function of this output as a weapon has been obvious for centuries but its potential role for electroreception has been overlooked. Here it is shown that electric eels use high-voltage simultaneously as a weapon and for precise and rapid electrolocation of fast-moving prey and conductors. Their speed, accuracy, and high-frequency pulse rate are reminiscent of bats using a 'terminal feeding buzz' to track insects. Eel's exhibit 'sensory conflict' when mechanosensory and electrosensory cues are separated, striking first toward mechanosensory cues and later toward conductors. Strikes initiated in the absence of conductors are aborted. In addition to providing new insights into the evolution of strongly electric fish and showing electric eels to be far more sophisticated than previously described, these findings reveal a trait with markedly dichotomous functions.

  11. Direct and fast detection of Alexandrium minutum algae by using high frequency microbalance.

    PubMed

    Sousa, Célia; Compère, Chantal; Dreanno, Catherine; Crassous, Marie-Pierre; Gas, Fabienne; Baus, Beatrice; Perrot, Hubert

    2014-09-01

    In this paper, a simple detection of a toxic algae, Alexandrium minutum, was developed using highly sensitive quartz crystal microbalance. In terms of performance, compared with other conventional analytical tools, the main interest of our immunosensor is based on a fast and direct detection of these living cells. This system requires the use of one monoclonal antibody directed against the surface antigen of A. minutum. We demonstrate that the whole living and motile algae are caught and detected. The high specificity of the biosensor is also demonstrated by testing several other dinoflagellate species. The frequency shift is correlated to the A. minutum cell concentration. This simple system is potentially promising for environmental monitoring purposes.

  12. LIGHT SCATTERING: Fast path-integration technique in simulation of light propagation through highly scattering objects

    NASA Astrophysics Data System (ADS)

    Voronov, Aleksandr V.; Tret'yakov, Evgeniy V.; Shuvalov, Vladimir V.

    2004-06-01

    Based on the path-integration technique and the Metropolis method, the original calculation scheme is developed for solving the problem of light propagation through highly scattering objects. The elimination of calculations of 'unnecessary' realisations and the phenomenological description of processes of multiple small-angle scattering provided a drastic increase (by nine and more orders of magnitude) in the calculation rate, retaining the specific features of the problem (consideration of spatial inhomogeneities, boundary conditions, etc.). The scheme allows one to verify other fast calculation algorithms and to obtain information required to reconstruct the internal structure of highly scattering objects (of size ~1000 scattered lengths and more) by the method of diffusion optical tomography.

  13. Research on fast ecological restoration technology of high and steep rocky slope of highway

    NASA Astrophysics Data System (ADS)

    Qin, Xin

    2017-08-01

    Along with the development of the western region, the traffic construction in mountainous areas is booming. In the infrastructure, it produced a large number of secondary bare land. Soil erosion is serious. Based on the literature search and analysis of the domestic and international slope ecological restoration technology, this paper proposes a fast and efficient adaptive highway high steep rock slope ecological restoration technology (it has been authorized by the national patent). And it states the systemic structure, working principle and key construction technology. The ecological restoration technique combines the growth characteristics of the vegetation and the characteristics of the rock mass, which not only improves the survival rate of plants, but also stable slope. The results of this study make up for the shortcomings of the existing ecological restoration technology of slope. Compared with the prior art, which have obvious advantages and suitable for the ecological restoration of high steep rock slope.

  14. High brightness gamma-ray production at Fermilab Accelerator Science and Technology (FAST) facility

    NASA Astrophysics Data System (ADS)

    Mihalcea, D.; Jacobson, B.; Murokh, A.; Piot, P.; Ruan, J.

    2017-03-01

    Electron beams with energies of the order of a few 100's of MeV and low transverse emittance, in combination with powerful infrared lasers, allow for the production of high quality gamma rays through Inverse Compton Scattering (ICS). At Fermilab Accelerator Science and Technology (FAST) facility, a 300 MeV beam will be used to generate gamma rays with maximum photon energies of up to ˜1.5 MeV and brightness of the order of 1021 photons/[s-(mm-mrad)2- 0.1%BW]. Due to the low electron-beam transverse emittance, the relative bandwidth of the scattered radiation is expected to be ≤ 1%. A key challenge toward the production of high radiation dose and brightness is to enhance the energy of the infrared 3 ps laser pulses to the joule level. In this contribution, we present the plans for the experimental setup, along with comprehensive numerical simulations of the ICS process.

  15. A high-order fast method for computing convolution integral with smooth kernel

    NASA Astrophysics Data System (ADS)

    Qiang, Ji

    2010-02-01

    In this paper we report on a high-order fast method to numerically calculate convolution integral with smooth non-periodic kernel. This method is based on the Newton-Cotes quadrature rule for the integral approximation and an FFT method for discrete summation. The method can have an arbitrarily high-order accuracy in principle depending on the number of points used in the integral approximation and a computational cost of O(Nlog(N)), where N is the number of grid points. For a three-point Simpson rule approximation, the method has an accuracy of O(h), where h is the size of the computational grid. Applications of the Simpson rule based algorithm to the calculation of a one-dimensional continuous Gauss transform and to the calculation of a two-dimensional electric field from a charged beam are also presented.

  16. A high-order fast method for computing convolution integral with smooth kernel

    SciTech Connect

    Qiang, Ji

    2009-09-28

    In this paper we report on a high-order fast method to numerically calculate convolution integral with smooth non-periodic kernel. This method is based on the Newton-Cotes quadrature rule for the integral approximation and an FFT method for discrete summation. The method can have an arbitrarily high-order accuracy in principle depending on the number of points used in the integral approximation and a computational cost of O(Nlog(N)), where N is the number of grid points. For a three-point Simpson rule approximation, the method has an accuracy of O(h{sup 4}), where h is the size of the computational grid. Applications of the Simpson rule based algorithm to the calculation of a one-dimensional continuous Gauss transform and to the calculation of a two-dimensional electric field from a charged beam are also presented.

  17. High School Dual Enrollment Programs: Are We Fast-Tracking Students Too Fast? An NCPR Working Paper

    ERIC Educational Resources Information Center

    Speroni, Cecilia

    2011-01-01

    Dual enrollment (DE), an arrangement by which high school students take college courses, is becoming increasingly popular as a means of improving high school education. However, there is very little rigorous evidence on its impact on student outcomes. A particular concern in evaluating its effects is the selection bias that arises because more…

  18. a Highly-Accurate and Fast Ray Tracing Sysyem for HF and UHF Simulations

    NASA Astrophysics Data System (ADS)

    Jones, J. C.; Richards, G. P.

    2016-12-01

    Accurate and fast ray tracing is critical for radiowave propagation tools and applications. A ray tracer needs to be accurate to reduce accumulated errors which come from the myriad of models (ionospheric electron density, magnetic field, ion density, neutral molecule density, absorption, land surface, ocean surface, and potentially others) required for accurate simulation. A ray tracer must also be fast to make the use of applications practical. Here we introduce NINJART Is Not Just Another Ray Tracer (NINJART), a highly accurate and fast ray tracing system. NINJART consists of an embarrassingly parallel algorithm rigorously solving the 3-D Hasselgrove equations with a Runge-Kutta adaptive step quadrature rule to accurately trace high frequency to ultra-high frequency radiowaves. It is capable of a wide range of propagation modes from multi-ground hops to vertical and near vertical incidence rays, chordal modes, and other esoteric paths. It is capable of using a variety of ionospheric models to include operational data assimilative or empirical models depending on the needs of the user. It can forward and backward ray trace, calculate time of flight, find the focus factor for signals near the skip zone and calculate the angle of arrival from a known transmitter to a known receiver location. Additionally NINJART uses magnetic field data from various models including the International Geomagnetic Reference Field to reduce the inaccuracies introduced by the simple dipole model, which is commonly used by other ray tracers, in calculating the effects of magneto-ionic splitting thereby allowing accurate traces of both the ordinary and extraordinary mode rays. The NINJART algorithm is a heterogeneous system utilizing the CUDA programming language to take advantage of the computing power of graphical processing units. This allows tracing of thousands of rays concurrently. NINJART achieves additional processing savings, without sacrificing accuracy, by use of an adaptive

  19. High-density lipoprotein remains elevated despite reductions in total cholesterol in fasting adult male elephant seals (Mirounga angustirostris).

    PubMed

    Tift, Michael S; Houser, Dorian S; Crocker, Daniel E

    2011-08-01

    We examined changes in lipid profiles of 40 adult northern elephant seal bulls over the 3-month breeding fast and the 1-month molting fast to investigate impacts of fasting on serum total cholesterol (TC), triglycerides (TG) and lipoproteins. Total cholesterol and low-density lipoprotein (LDL) levels were initially high (3930 ± 190mgL(-1)and 1610 ± 170mgL(-1), respectively) and decreased significantly over the breeding season. Total cholesterol and LDL declined significantly with adipose tissue reserves (p<0.001), and LDL levels as low as 43 mgL(-1) were measured in seals late in the breeding fast. Less dramatic but similar changes in lipid metabolism were observed across the molting fast. High-density lipoproteins (HDL) remained consistently elevated (>1750 mgL(-1)) suggesting that elephant seals defend HDL concentrations, despite significant depletion of TC and LDL across the breeding fast. Triglyceride levels were significantly higher during the molt, consistent with lower rates of lipid oxidation needed to meet metabolic energy demands during this period. The maintenance of HDL during breeding is consistent with its role in delivering cholesterol from adipose tissue for steroidogenesis and spermatogenesis and potentially mitigates oxidative stress associated with fasting.

  20. Fast switching thyristor applied in nanosecond-pulse high-voltage generator with closed transformer core

    NASA Astrophysics Data System (ADS)

    Li, Lee; Bao, Chaobing; Feng, Xibo; Liu, Yunlong; Fochan, Lin

    2013-02-01

    For a compact and reliable nanosecond-pulse high-voltage generator (NPHVG), the specification parameter selection and potential usage of fast controllable state-solid switches have an important bearing on the optimal design. The NPHVG with closed transformer core and fast switching thyristor (FST) was studied in this paper. According to the analysis of T-type circuit, the expressions for the voltages and currents of the primary and secondary windings on the transformer core of NPHVG were deduced, and the theoretical maximum analysis was performed. For NPHVG, the rise-rate of turn-on current (di/dt) across a FST may exceed its transient rating. Both mean and maximum values of di/dt were determined by the leakage inductances of the transformer, and the difference is 1.57 times. The optimum winding ratio is helpful to getting higher voltage output with lower specification FST, especially when the primary and secondary capacitances have been established. The oscillation period analysis can be effectively used to estimate the equivalent leakage inductance. When the core saturation effect was considered, the maximum di/dt estimated from the oscillating period of the primary current is more accurate than one from the oscillating period of the secondary voltage. Although increasing the leakage inductance of NPHVG can decrease di/dt across FST, it may reduce the output peak voltage of the NPHVG.

  1. A fast and high accuracy numerical simulation algorithm of the polymer spherulite at the mesoscale Level

    NASA Astrophysics Data System (ADS)

    Liu, Yongzhi; Geng, Tie; (Tom Turng, Lih-Sheng; Liu, Chuntai; Cao, Wei; Shen, Changyu

    2017-09-01

    In the multiscale numerical simulation of polymer crystallization during the processing period, flow and temperature of the polymer melt are simulated on the macroscale level, while nucleation and growth of the spherulite are simulated at the mesoscale level. As a part of the multiscale simulation, the meso-simulation requires a fast solving speed because the meso-simulation software must be run several times in every macro-element at each macro-step. Meanwhile, the accuracy of the calculation results is also very important. It is known that the simulation geometry of crystallization includes planar (2D) and three-dimensional space (3D). The 3D calculations are more accurate but more expensive because of the long CPU time consumed. On the contrary, 2D calculations are always much faster but lower in accuracy. To reach the desirable speed and high accuracy at the same time, an algorithm is presented, in which the Delesse law coupled with the Monte Carlo method and pixel method are employed to simulate the nucleation, growth, and impingement of the polymer spherulite at the mesoscale level. Based on this algorithm, a software is developed with the Visual C++ language, and its numerical examples’ results prove that the solving speed of this algorithm is as fast as the 2D classical simulation and the calculation accuracy is at the same level as the 3D simulation.

  2. A display module implemented by the fast high-temperatue response of carbon nanotube thin yarns.

    PubMed

    Wei, Yang; Liu, Peng; Jiang, Kaili; Fan, Shoushan

    2012-05-09

    Suspending superaligned multiwalled carbon nanotube (MWCNT) films were processed into CNT thin yarns, about 1 μm in diameter, by laser cutting and an ethanol atomization bath treatment. The fast high-temperature response under a vacuum was revealed by monitoring the incandescent light with a photo diode. The thin yarns can be electrically heated up to 2170 K in 0.79 mS, and the succeeding cool-down time is 0.36 mS. The fast response is attributed to the ultrasmall mass of the independent single yarn, large radiation coefficient, and improved thermal conductance through the two cool ends. The millisecond response time makes it possible to use the visible hot thin yarns as light-emitting elements of an incandescent display. A fully sealed display with 16 × 16 matrix was successfully fabricated using screen-printed thick electrodes and CNT thin yarns. It can display rolling characters with a low power consumption. More applications can be further developed based on the addressable CNT thermal arrays.

  3. High yield bio-oil production from fast pyrolysis by metabolic controlling of Chlorella protothecoides.

    PubMed

    Miao, Xiaoling; Wu, Qingyu

    2004-05-13

    The use of renewable energy sources is becoming increasingly necessary to mitigate global warming. Recently much research has been focused on identifying suitable biomass species, which can provide high-energy outputs, to replace conventional fossil fuels. This paper reports an approach for increasing the yield of bio-oil production from fast pyrolysis after manipulating the metabolic pathway in microalgae through heterotrophic growth. The yield of bio-oil (57.9%) produced from heterotrophic Chlorella protothecoides cells was 3.4 times higher than from autotrophic cells by fast pyrolysis. The bio-oil was characterized by a much lower oxygen content, with a higher heating value (41 MJ kg(-1)), a lower density (0.92 kg l(-1)), and lower viscosity (0.02 Pas) compared to those of bio-oil from autotrophic cells and wood. These properties are comparable to fossil oil. The research could contribute to the creation of a system to produce energy from microalgae, and also could have great commercial potential for liquid fuel production.

  4. Characterization of a fast CMOS imaging sensor for high-speed laser detection

    NASA Astrophysics Data System (ADS)

    Casadei, Bruno; Le Normand, J. P.; Hu, Y.; Cunin, Bernard

    2003-07-01

    CMOS active pixel sensors (APS) have performances competitive with charge-coupled device (CCD) technology, and offer advantages in on-chip functionality, system power reduction, cost and miniaturization. In this paper, we present characterization of a fast CMOS APS used in an imager for high-speed laser detections, which can replace the streak cameras. It produces the intensity information in function of one spatial dimension and time [I = f(x,t)] from one frame in two spatial dimensions. The time information is obtained for the first prototype camera to delay successively the integration phase in each pixel of the same row. The different noise sources of the APS sensors such as shot noise due to the photo sensor, the thermal noise and flicker noise due to the readout transistors and the photon shot noise are presented to determine the fundamental limits on image sensor. The first prototype FAMOSI (FAst MOS Imager) is composed of 64 x 64 active pixels. The simulation and experimental results show that a conversion gain of 6.73 +/- 0.25 μV/e- has been obtained with a noise level of 87 +/- 3e- rms. The power consumption of the chip is 25 mW at 50 images/sec.

  5. Fast switching thyristor applied in nanosecond-pulse high-voltage generator with closed transformer core.

    PubMed

    Li, Lee; Bao, Chaobing; Feng, Xibo; Liu, Yunlong; Fochan, Lin

    2013-02-01

    For a compact and reliable nanosecond-pulse high-voltage generator (NPHVG), the specification parameter selection and potential usage of fast controllable state-solid switches have an important bearing on the optimal design. The NPHVG with closed transformer core and fast switching thyristor (FST) was studied in this paper. According to the analysis of T-type circuit, the expressions for the voltages and currents of the primary and secondary windings on the transformer core of NPHVG were deduced, and the theoretical maximum analysis was performed. For NPHVG, the rise-rate of turn-on current (di/dt) across a FST may exceed its transient rating. Both mean and maximum values of di/dt were determined by the leakage inductances of the transformer, and the difference is 1.57 times. The optimum winding ratio is helpful to getting higher voltage output with lower specification FST, especially when the primary and secondary capacitances have been established. The oscillation period analysis can be effectively used to estimate the equivalent leakage inductance. When the core saturation effect was considered, the maximum di/dt estimated from the oscillating period of the primary current is more accurate than one from the oscillating period of the secondary voltage. Although increasing the leakage inductance of NPHVG can decrease di/dt across FST, it may reduce the output peak voltage of the NPHVG.

  6. Ultra-Fast Timing and the Application of High Energy Physics Technologies to Biomedical Imaging

    NASA Astrophysics Data System (ADS)

    Chen, Chin-Tu; Kao, Chien-Min; Xie, Quigguo; Frisch, Henry; Heinz, Mary; Sanders, Harold; Tang, Fukung; Anderson, John; Byrum, Karen; Drake, Gary; Heartly, Camden; Le Dû, Patrick; Royon, Christophe; Genat, Jean François; Va'Vra, Jerry

    2008-06-01

    We propose to apply the ultra fast Time Of Flight technique (TOF) developed for High Energy Physics (HEP) particle detectors to biomedical imaging. The similarity of the problem in the two fields as well as the remarkable opportunities in biomedical imaging to use technologies developed in HEP have the potential to make major advances in the medical world, in particular for Positron Emission Tomography (PET). We will describe and present some preliminary results of the development of a new complete read-out chain able to manage signals from various types of modern photo detectors (MCP, APD, SiPM). This innovative architecture is made of a fast front-end electronics ASIC with novel Digital Signal Processing (DSP) concepts able to reach the Pico-second timing resolution, a time-to-digital converter, a pipelined digital readout and an integrated trigger/filter with real-time data treatment and display. In parallel with the hardware development, we have begun a systematic program to simulate system characteristics from the initial particle interaction to the final digital data, including a bit-by-bit mapping of the front end/data acquisition system. The introduction of these techniques and tools, common in HEP, has the potential to make improvement to biomedical imaging systems.

  7. High Harmonic Fast Wave Damping on an Ion Beam: NSTX and DIII-D Regimes Compared

    NASA Astrophysics Data System (ADS)

    Pinsker, R. I.; Choi, C. C.; Petty, C. C.; Porkolab, M.; Wilson, J. R.; Murakami, M.; Harvey, R. W.

    2004-11-01

    Both NSTX and DIII-D use the combination of fast Alfven waves (FW) and neutral beam injection (NBI) for central electron heating and current drive. Damping of the fast wave on the beam ions at moderate to high harmonics (4th--20th) of the beam ion cyclotron frequency represents a loss process. In DIII-D current drive experiments at low density in which 4th and 8th harmonics were compared, damping at the 8th harmonic damping was much weaker than at the 4th [1]. However, recent simulations have predicted that in higher density and higher beam power regimes (of interest to the Advanced Tokamak program) the beam ion absorption will transition to the unmagnetized ion regime, where the damping is significant and essentially independent of harmonic number. In the present work, the transition from magnetized to unmagnetized ion regimes for the NSTX and DIII-D HHFW experiments is studied theoretically, with a combination of simple semi-analytic models and numerical models. \\vspace0.25 em [1] C.C. Petty, et al., Plasma Phys. and Contr. Fusion 43, 1747 (2001).

  8. Towards the understanding of PETN initiation by a fast, high power arc source

    SciTech Connect

    Grant, C D; Tang, V; Glascoe, E A; McCarrick, J F

    2010-03-05

    We present a thorough characterization of a capacitor driven arc source that can deliver up to 200 mJ of energy to the arc and high explosive in a well-controlled, repeatable manner on the hundreds of nanoseconds time-scale. Our ultimate purpose is to create a platform to study high explosive kinetics under extreme conditions of high-temperature. In the current paper, we characterize the behavior of our arc source by electrical discharge over a thin PETN film. Temperature and density are determined by time-resolved atomic emission spectroscopy on the nano- to microsecond time scale along with fast photographic imaging to capture time-resolved images of the expanding plasma. We also discuss preliminary simulations of arc plasma using a 1-D hydrodynamic model. Comparisons of these simulations with experimental data are presented. Ultimately our goal is to create a platform that will generate conditions of high temperature in order to study high explosive kinetics. We believe that our arc source platform can be further combined with a time-resolved vibrational spectroscopy (e.g. IR or Raman) to study chemical kinetics under extreme conditions. High temperature conditions may access novel reactive pathways that are different from either shock or slower thermal processes that are substantially lower in temperature.

  9. Demonstration of high-rate laser communications from fast airborne platform: flight campaign and results

    NASA Astrophysics Data System (ADS)

    Moll, Florian; Mitzkus, Wolfgang; Horwath, Joachim; Shrestha, Amita; Brechtelsbauer, Martin; Martin, Luis; Lozano, Alberto; Diaz Gonzalez, Dionisio

    2014-10-01

    Some current and future airborne payloads like high resolution cameras and radar systems need high channel capacity to transmit their data from air to ground in near real-time. Especially in reconnaissance and surveillance missions, it is important to downlink huge amount of data in very short contact times to a ground station during a flyby. Aeronautical laser communications can supply the necessary high data-rates for this purpose. Within the project DODfast (Demonstration of Optical Data link fast) a laser link from a fast flying platform was demonstrated. The flight platform was a Panavia Tornado with the laser communication terminal installed in an attached avionic demonstrator pod. The air interface was a small glass dome protecting the beam steering assembly. All other elements were integrated in a small box inside the Pod's fuselage. The receiver station was DLR's Transportable Optical Ground Station equipped with a free-space receiver front-end. Downlink wavelength for communication and uplink wavelength for beacon laser were chosen from the optical C-band DWDM grid. The test flights were carried out at the end of November 2013 near the Airbus Defence and Space location in Manching, Germany. The campaign successfully demonstrated the maturity and readiness of laser communication with a data-rate of 1.25 Gbit/s for aircraft downlinks. Pointing, acquisition and tracking performance of the airborne terminal and the ground station could be measured at aircraft speed up to 0.7 Mach and video data from an onboard camera has been transmitted. Link distances with stable tracking were up to 79 km and distance with data transmission over 50 km. In this paper, we describe the system architecture, the flight campaign and the results.

  10. High-frame rate imaging of two-phase flow in a thin rectangular channel using fast neutrons.

    PubMed

    Zboray, R; Mor, I; Dangendorf, V; Stark, M; Tittelmeier, K; Cortesi, M; Adams, R

    2014-08-01

    We have demonstrated the feasibility of performing high-frame-rate, fast neutron radiography of air-water two-phase flows in a thin channel with rectangular cross section. The experiments have been carried out at the accelerator facility of the Physikalisch-Technische Bundesanstalt. A polychromatic, high-intensity fast neutron beam with average energy of 6 MeV was produced by 11.5 MeV deuterons hitting a thick Be target. Image sequences down to 10 ms exposure times were obtained using a fast-neutron imaging detector developed in the context of fast-neutron resonance imaging. Different two-phase flow regimes such as bubbly slug and churn flows have been examined. Two phase flow parameters like the volumetric gas fraction, bubble size and mean bubble velocities have been measured. The first results are promising, improvements for future experiments are also discussed. Copyright © 2014 Elsevier Ltd. All rights reserved.

  11. Guiding and collimating the fast electrons by using a low-density-core target with buried high density layers

    NASA Astrophysics Data System (ADS)

    Lv, Chong; Wan, Feng; Hou, Ya-Juan; Jia, Mo-Ran; Sang, Hai-Bo; Xie, Bai-Song; Liu, Shi-Bing

    2017-02-01

    A low-density-core target with buried high density layers is proposed to improve the transport of fast electrons and involved problems are investigated by using two-dimensional particle-in-cell simulations. It is demonstrated that this target can collimate the fast electrons efficiently and lead to a better beam quality. The enhancement is attributed to the weakening of the two stream instability and the better collimation by the self-generated multilayer megagauss magnetic field as well as the baroclinic magnetic field. Comparing this to that without buried high density layers, the energy flux of fast electrons is increased by a factor of about 1.8 and has a narrower transverse distribution in space. Besides, the dependence of the efficiency on the target parameters is examined, and the optimal target parameters are also obtained. Such a target can be useful to many applications, such as fast ignition in inertial fusion.

  12. The high current, fast, 100ns, Linear Transformer Driver (LTD) developmental project at Sandia National Laboratories.

    SciTech Connect

    Ward, Kevin S.; Long, Finis W.; Sinebryukhov, Vadim A. , Tomsk, Russia); Kim, Alexandre A. , Tomsk, RUSSIA); Wakeland, Peter Eric; McKee, G. Randall; Woodworth, Joseph Ray; McDaniel, Dillon Heirman; Fowler, William E.; Mazarakis, Michael Gerrassimos; Porter, John Larry, Jr.; Struve, Kenneth William; Stygar, William A.; LeChien, Keith R.; Matzen, Maurice Keith

    2010-04-01

    Sandia National Laboratories, Albuquerque, N.M., USA, in collaboration with the High Current Electronic Institute (HCEI), Tomsk, Russia, is developing a new paradigm in pulsed power technology: the Linear Transformer Driver (LTD) technology. This technological approach can provide very compact devices that can deliver very fast high current and high voltage pulses straight out of the cavity with out any complicated pulse forming and pulse compression network. Through multistage inductively insulated voltage adders, the output pulse, increased in voltage amplitude, can be applied directly to the load. The load may be a vacuum electron diode, a z-pinch wire array, a gas puff, a liner, an isentropic compression load (ICE) to study material behavior under very high magnetic fields, or a fusion energy (IFE) target. This is because the output pulse rise time and width can be easily tailored to the specific application needs. In this paper we briefly summarize the developmental work done in Sandia and HCEI during the last few years, and describe our new MYKONOS Sandia High Current LTD Laboratory.

  13. Simple Fabrication of a Highly Sensitive and Fast Glucose Biosensor using Enzyme Immobilized in Mesocellular Carbon Foam

    SciTech Connect

    Lee, Dohoon; Lee, Jinwoo; Kim, Jungbae; Kim, Jaeyun; Na, Hyon Bin; Kim, Bokie; Shin, Chae-Ho; Kwak, Ja Hun; Dohnalkova, Alice; Grate, Jay W.; Hyeon, Taeghwan; Kim, Hak Sung

    2005-12-05

    We fabricated a highly sensitive and fast glucose biosensor by simply immobilizing glucose oxidase in mesocellular carbon foam. Due to its unique structure, the MSU-F-C enabled high enzyme loading without serious mass transfer limitation, resulting in high catalytic efficiency. As a result, the glucose biosensor fabricated with MSU-F-C/GOx showed a high sensitivity and fast response. Given these results and the inherent electrical conductivity, we anticipate that MSU-F-C will make a useful matrix for enzyme immobilization in various biocatalytic and electrobiocatalytic applications.

  14. Development of fast cooling pulsed magnets at the Wuhan National High Magnetic Field Center

    NASA Astrophysics Data System (ADS)

    Peng, Tao; Sun, Quqin; Zhao, Jianlong; Jiang, Fan; Li, Liang; Xu, Qiang; Herlach, Fritz

    2013-12-01

    Pulsed magnets with fast cooling channels have been developed at the Wuhan National High Magnetic Field Center. Between the inner and outer sections of a coil wound with a continuous length of CuNb wire, G10 rods with cross section 4 mm × 5 mm were inserted as spacers around the entire circumference, parallel to the coil axis. The free space between adjacent rods is 6 mm. The liquid nitrogen flows freely in the channels between these rods, and in the direction perpendicular to the rods through grooves provided in the rods. For a typical 60 T pulsed magnetic field with pulse duration of 40 ms, the cooling time between subsequent pulses is reduced from 160 min to 35 min. Subsequently, the same technology was applied to a 50 T magnet with 300 ms pulse duration. The cooling time of this magnet was reduced from 480 min to 65 min.

  15. Modeling of low- and high-frequency noise by slow and fast fluctuators

    NASA Astrophysics Data System (ADS)

    Nesterov, Alexander I.; Berman, Gennady P.

    2012-05-01

    We study the dynamics of dephasing in a quantum two-level system by modeling both 1/f and high-frequency noise by random telegraph processes. Our approach is based on a so-called spin-fluctuator model in which a noisy environment is modeled by a large number of fluctuators. In the continuous limit we obtain an effective random process (ERP) that is described by a distribution function of the fluctuators. In a simplified model, we reduce the ERP to the two (slow and fast) ensembles of fluctuators. Using this model, we study decoherence in a superconducting flux qubit and we compare our theoretical results with the available experimental data. We demonstrate good agreement of our theoretical predictions with the experiments. Our approach can be applied to many quantum systems, such as biological complexes, semiconductors, superconducting, and spin qubits, where the effects of interaction with the environment are essential.

  16. A fast and automatic mosaic method for high-resolution satellite images

    NASA Astrophysics Data System (ADS)

    Chen, Hongshun; He, Hui; Xiao, Hongyu; Huang, Jing

    2015-12-01

    We proposed a fast and fully automatic mosaic method for high-resolution satellite images. First, the overlapped rectangle is computed according to geographical locations of the reference and mosaic images and feature points on both the reference and mosaic images are extracted by a scale-invariant feature transform (SIFT) algorithm only from the overlapped region. Then, the RANSAC method is used to match feature points of both images. Finally, the two images are fused into a seamlessly panoramic image by the simple linear weighted fusion method or other method. The proposed method is implemented in C++ language based on OpenCV and GDAL, and tested by Worldview-2 multispectral images with a spatial resolution of 2 meters. Results show that the proposed method can detect feature points efficiently and mosaic images automatically.

  17. Development of fast cooling pulsed magnets at the Wuhan National High Magnetic Field Center

    SciTech Connect

    Peng, Tao; Sun, Quqin; Zhao, Jianlong; Jiang, Fan; Li, Liang; Xu, Qiang; Herlach, Fritz

    2013-12-15

    Pulsed magnets with fast cooling channels have been developed at the Wuhan National High Magnetic Field Center. Between the inner and outer sections of a coil wound with a continuous length of CuNb wire, G10 rods with cross section 4 mm × 5 mm were inserted as spacers around the entire circumference, parallel to the coil axis. The free space between adjacent rods is 6 mm. The liquid nitrogen flows freely in the channels between these rods, and in the direction perpendicular to the rods through grooves provided in the rods. For a typical 60 T pulsed magnetic field with pulse duration of 40 ms, the cooling time between subsequent pulses is reduced from 160 min to 35 min. Subsequently, the same technology was applied to a 50 T magnet with 300 ms pulse duration. The cooling time of this magnet was reduced from 480 min to 65 min.

  18. A high-field adiabatic fast passage ultracold neutron spin flipper for the UCNA experiment.

    PubMed

    Holley, A T; Broussard, L J; Davis, J L; Hickerson, K; Ito, T M; Liu, C-Y; Lyles, J T M; Makela, M; Mammei, R R; Mendenhall, M P; Morris, C L; Mortensen, R; Pattie, R W; Rios, R; Saunders, A; Young, A R

    2012-07-01

    The UCNA collaboration is making a precision measurement of the β asymmetry (A) in free neutron decay using polarized ultracold neutrons (UCN). A critical component of this experiment is an adiabatic fast passage neutron spin flipper capable of efficient operation in ambient magnetic fields on the order of 1 T. The requirement that it operate in a high field necessitated the construction of a free neutron spin flipper based, for the first time, on a birdcage resonator. The design, construction, and initial testing of this spin flipper prior to its use in the first measurement of A with UCN during the 2007 run cycle of the Los Alamos Neutron Science Center's 800 MeV proton accelerator is detailed. These studies determined the flipping efficiency of the device, averaged over the UCN spectrum present at the location of the spin flipper, to be ̅ε=0.9985(4).

  19. A high-field adiabatic fast passage ultracold neutron spin flipper for the UCNA experiment

    NASA Astrophysics Data System (ADS)

    Holley, A. T.; Broussard, L. J.; Davis, J. L.; Hickerson, K.; Ito, T. M.; Liu, C.-Y.; Lyles, J. T. M.; Makela, M.; Mammei, R. R.; Mendenhall, M. P.; Morris, C. L.; Mortensen, R.; Pattie, R. W.; Rios, R.; Saunders, A.; Young, A. R.

    2012-07-01

    The UCNA collaboration is making a precision measurement of the β asymmetry (A) in free neutron decay using polarized ultracold neutrons (UCN). A critical component of this experiment is an adiabatic fast passage neutron spin flipper capable of efficient operation in ambient magnetic fields on the order of 1 T. The requirement that it operate in a high field necessitated the construction of a free neutron spin flipper based, for the first time, on a birdcage resonator. The design, construction, and initial testing of this spin flipper prior to its use in the first measurement of A with UCN during the 2007 run cycle of the Los Alamos Neutron Science Center's 800 MeV proton accelerator is detailed. These studies determined the flipping efficiency of the device, averaged over the UCN spectrum present at the location of the spin flipper, to be overline{ɛ }=0.9985(4).

  20. Fast cavity-enhanced atom detection with low noise and high fidelity.

    PubMed

    Goldwin, J; Trupke, M; Kenner, J; Ratnapala, A; Hinds, E A

    2011-08-09

    Cavity quantum electrodynamics describes the fundamental interactions between light and matter, and how they can be controlled by shaping the local environment. For example, optical microcavities allow high-efficiency detection and manipulation of single atoms. In this regime, fluctuations of atom number are on the order of the mean number, which can lead to signal fluctuations in excess of the noise on the incident probe field. Here we demonstrate, however, that nonlinearities and multi-atom statistics can together serve to suppress the effects of atomic fluctuations when making local density measurements on clouds of cold atoms. We measure atom densities below 1 per cavity mode volume near the photon shot-noise limit. This is in direct contrast to previous experiments where fluctuations in atom number contribute significantly to the noise. Atom detection is shown to be fast and efficient, reaching fidelities in excess of 97% after 10 μs and 99.9% after 30 μs.

  1. Fast asthenosphere motion in high-resolution global mantle flow models

    NASA Astrophysics Data System (ADS)

    Weismüller, Jens; Gmeiner, Björn; Ghelichkhan, Siavash; Huber, Markus; John, Lorenz; Wohlmuth, Barbara; Rüde, Ulrich; Bunge, Hans-Peter

    2015-09-01

    A variety of geologic observations point to fast upper mantle flow that may exceed plate tectonic velocities by an order of magnitude. At the same time there is mounting evidence from seismology for flow-like structures in the upper 100-200 km of the mantle. Here we present a set of geodynamic simulations to link these observations. In a synthetic setting, we include asthenospheric channels of varying thickness, with an extreme case of 100 km, and a significant viscosity contrast of up to 4 orders of magnitude relative to the deeper mantle. Using our new global high-resolution code TERRA-NEO, we obtain an increase in velocity by a factor of 10 between a 1000 km thick and the very thin channel, translating into velocities of ˜ 20 cm/a within the narrow asthenosphere. We further present and verify a simple Poiseuille flow model, predicting that the upper mantle velocity scales with the inverse of the asthenosphere thickness.

  2. Development of fast cooling pulsed magnets at the Wuhan National High Magnetic Field Center.

    PubMed

    Peng, Tao; Sun, Quqin; Zhao, Jianlong; Jiang, Fan; Li, Liang; Xu, Qiang; Herlach, Fritz

    2013-12-01

    Pulsed magnets with fast cooling channels have been developed at the Wuhan National High Magnetic Field Center. Between the inner and outer sections of a coil wound with a continuous length of CuNb wire, G10 rods with cross section 4 mm × 5 mm were inserted as spacers around the entire circumference, parallel to the coil axis. The free space between adjacent rods is 6 mm. The liquid nitrogen flows freely in the channels between these rods, and in the direction perpendicular to the rods through grooves provided in the rods. For a typical 60 T pulsed magnetic field with pulse duration of 40 ms, the cooling time between subsequent pulses is reduced from 160 min to 35 min. Subsequently, the same technology was applied to a 50 T magnet with 300 ms pulse duration. The cooling time of this magnet was reduced from 480 min to 65 min.

  3. Leaf hue measurements offer a fast, high-throughput initial screening of photosynthesis in leaves.

    PubMed

    Majer, Petra; Sass, László; Horváth, Gábor V; Hideg, Eva

    2010-01-01

    Experiments with tobacco and grapevine leaves having different color due to varying stages of senescence showed that leaf hue is significantly linearly correlated with chlorophyll content up to 80% loss of pigment. Samples from leaves with more pronounced loss of chlorophyll did not fit into this linear relationship, and the hue data set as a whole followed a saturating exponential dependence on chlorophyll content. In leaves with less than 80% chlorophyll loss, the hue parameter was also proportional to the photochemical yield of photosystem (PS) II measured in the light. These results suggest that leaf hue measurements offer a fast, high-throughput initial screening system to precede more specific but more time consuming photosynthesis measurements, with the possibility of applications not only for senescing plants, but also for stress conditions accompanied by chlorophyll loss.

  4. Fast 3D visualization of endogenous brain signals with high-sensitivity laser scanning photothermal microscopy

    PubMed Central

    Miyazaki, Jun; Iida, Tadatsune; Tanaka, Shinji; Hayashi-Takagi, Akiko; Kasai, Haruo; Okabe, Shigeo; Kobayashi, Takayoshi

    2016-01-01

    A fast, high-sensitivity photothermal microscope was developed by implementing a spatially segmented balanced detection scheme into a laser scanning microscope. We confirmed a 4.9 times improvement in signal-to-noise ratio in the spatially segmented balanced detection compared with that of conventional detection. The system demonstrated simultaneous bi-modal photothermal and confocal fluorescence imaging of transgenic mouse brain tissue with a pixel dwell time of 20 μs. The fluorescence image visualized neurons expressing yellow fluorescence proteins, while the photothermal signal detected endogenous chromophores in the mouse brain, allowing 3D visualization of the distribution of various features such as blood cells and fine structures probably due to lipids. This imaging modality was constructed using compact and cost-effective laser diodes, and will thus be widely useful in the life and medical sciences. PMID:27231615

  5. Simulations of a fast feedback system for the High Luminosity LHC

    NASA Astrophysics Data System (ADS)

    Daw, Aron; Mastoridis, Themistoklis; Nguyen, Philippe

    2017-01-01

    The High-Luminosity LHC upgrade, expected to be finished by 2025, will generate a tenfold increase in the number of recorded collisions. Part of this improvement will come from the implementation of crab cavities, which exert transverse momentum kicks on the bunches of particles just before they collide, in order to have head-on collisions. The crab cavity field will include amplitude and phase noise, leading to undesirable consequences, such as the increase of the particle cloud size (emittance). Simulations were performed to evaluate the performance improvement with a proposed fast feedback system acting through the crab cavities. This work is supported by the National Science Foundation under Grant No. PHY-1535536.

  6. Force Modelling of Upper Limb Biomechanics Using Ensemble Fast Orthogonal Search on High-Density Electromyography.

    PubMed

    Johns, Gregg; Morin, Evelyn; Hashtrudi-Zaad, Keyvan

    2016-10-01

    An important quality of upper limb force estimation is the repeatability and worst-case performance of the estimator. The following paper proposes a methodology using an ensemble learning technique coupled with the fast orthogonal search (FOS) algorithm to reliably predict varying isometric contractions of the right arm. This method leverages the rapid and precise modelling offered by FOS combined with a univariate outlier detection algorithm to dynamically combine the output of numerous FOS models. This is performed using high-density surface electromyography (HD-SEMG) obtained from three upper-arm muscles, the biceps brachii, triceps brachii and brachioradialis. This method offers improved performance over other HD-SEMG and SEMG based force estimators, with a substantial reduction in the number of channels required.

  7. Fast high-pressure freezing of protein crystals in their mother liquor

    PubMed Central

    Burkhardt, Anja; Warmer, Martin; Panneerselvam, Saravanan; Wagner, Armin; Zouni, Athina; Glöckner, Carina; Reimer, Rudolph; Hohenberg, Heinrich; Meents, Alke

    2012-01-01

    High-pressure freezing (HPF) is a method which allows sample vitrification without cryoprotectants. In the present work, protein crystals were cooled to cryogenic temperatures at a pressure of 210 MPa. In contrast to other HPF methods published to date in the field of cryocrystallography, this protocol involves rapid sample cooling using a standard HPF device. The fast cooling rates allow HPF of protein crystals directly in their mother liquor without the need for cryoprotectants or external reagents. HPF was first attempted with hen egg-white lysozyme and cubic insulin crystals, yielding good to excellent diffraction quality. Non-cryoprotected crystals of the membrane protein photosystem II have been successfully cryocooled for the first time. This indicates that the presented HPF method is well suited to the vitrification of challenging systems with large unit cells and weak crystal contacts. PMID:22505429

  8. Quantitative FRET Analysis by Fast Acquisition Time Domain FLIM at High Spatial Resolution in Living Cells

    PubMed Central

    Padilla-Parra, Sergi; Audugé, Nicolas; Coppey-Moisan, Maïté; Tramier, Marc

    2008-01-01

    Quantitative analysis in Förster resonance energy transfer (FRET) experiments in live cells for protein interaction studies is still a challenging issue. In a two-component system (FRET and no FRET donor species), fitting of fluorescence lifetime imaging microscopy (FLIM) data gives the fraction of donor molecules involved in FRET (fD) and the intrinsic transfer efficiency. But when fast FLIM acquisitions are used to monitor dynamic changes in protein-protein interactions at high spatial and temporal resolutions in living cells, photon statistics and time resolution are limited. In this case, fitting procedures are not reliable, even for single lifetime donors. We introduce the new concept of a minimal fraction of donor molecules involved in FRET (mfD), coming from the mathematical minimization of fD. We find particular advantage in the use of mfD because it can be obtained without fitting procedures and it is derived directly from FLIM data. mfD constitutes an interesting quantitative parameter for live cell studies because it is related to the minimal relative concentration of interacting proteins. For multi-lifetime donors, the process of fitting complex fluorescence decays to find at least four reliable lifetimes is a near impossible task. Here, mfD extension for multi-lifetime donors is the only quantitative determinant. We applied this methodology for imaging the interaction between the bromodomains of TAFII250 and acetylated histones H4 in living cells at high resolution. We show the existence of discrete acetylated chromatin domains where the minimal fraction of bromodomain interacting with acetylated H4 oscillates from 0.26 to 0.36 and whose size is smaller than half of one micron cube. We demonstrate that mfD by itself is a useful tool to investigate quantitatively protein interactions in live cells, especially when using fast FRET-FLIM acquisition times. PMID:18539634

  9. Fast computation of high energy elastic collision scattering angle for electric propulsion plume simulation

    NASA Astrophysics Data System (ADS)

    Araki, Samuel J.

    2016-11-01

    In the plumes of Hall thrusters and ion thrusters, high energy ions experience elastic collisions with slow neutral atoms. These collisions involve a process of momentum exchange, altering the initial velocity vectors of the collision pair. In addition to the momentum exchange process, ions and atoms can exchange electrons, resulting in slow charge-exchange ions and fast atoms. In these simulations, it is particularly important to accurately perform computations of ion-atom elastic collisions in determining the plume current profile and assessing the integration of spacecraft components. The existing models are currently capable of accurate calculation but are not fast enough such that the calculation can be a bottleneck of plume simulations. This study investigates methods to accelerate an ion-atom elastic collision calculation that includes both momentum- and charge-exchange processes. The scattering angles are pre-computed through a classical approach with ab initio spin-orbit free potential and are stored in a two-dimensional array as functions of impact parameter and energy. When performing a collision calculation for an ion-atom pair, the scattering angle is computed by a table lookup and multiple linear interpolations, given the relative energy and randomly determined impact parameter. In order to further accelerate the calculations, the number of collision calculations is reduced by properly defining two cut-off cross-sections for the elastic scattering. In the MCC method, the target atom needs to be sampled; however, it is confirmed that initial target atom velocity does not play a significant role in typical electric propulsion plume simulations such that the sampling process is unnecessary. With these implementations, the computational run-time to perform a collision calculation is reduced significantly compared to previous methods, while retaining the accuracy of the high fidelity models.

  10. High rate, fast timing Glass RPC for the high η CMS muon detectors

    NASA Astrophysics Data System (ADS)

    Gouzevitch, M.; Lagarde, F.; Laktineh, I.; Buridon, V.; Chen, X.; Combaret, C.; Eynard, A.; Germani, L.; Grenier, G.; Mathez, H.; Mirabito, L.; Petrukhin, A.; Steen, A.; Tromeur, W.; Wang, Y.; Gong, A.; Moreau, N.; Taille, C. de la; Dulucq, F.

    2017-02-01

    The HL-LHC phase is designed to increase by an order of magnitude the amount of data to be collected by the LHC experiments. To achieve this goal in a reasonable time scale the instantaneous luminosity would also increase by an order of magnitude up to 6 ·1034cm-2s-1 . The region of the forward muon spectrometer (| η | > 1.6) is not equipped with RPC stations. The increase of the expected particles rate up to 2 kHz/cm2 (including a safety factor 3) motivates the installation of RPC chambers to guarantee redundancy with the CSC chambers already present. The actual RPC technology of CMS cannot sustain the expected background level. A new generation Glass-RPC (GRPC) using low resistivity glass (LR) is proposed to equip at least the two most far away of the four high eta muon stations of CMS Butler et al. (2015). The design of small size prototypes and the studies of their performances under high rate particles flux is presented.

  11. Ultra-high throughput real-time instruments for capturing fast signals and rare events

    NASA Astrophysics Data System (ADS)

    Buckley, Brandon Walter

    Wide-band signals play important roles in the most exciting areas of science, engineering, and medicine. To keep up with the demands of exploding internet traffic, modern data centers and communication networks are employing increasingly faster data rates. Wide-band techniques such as pulsed radar jamming and spread spectrum frequency hopping are used on the battlefield to wrestle control of the electromagnetic spectrum. Neurons communicate with each other using transient action potentials that last for only milliseconds at a time. And in the search for rare cells, biologists flow large populations of cells single file down microfluidic channels, interrogating them one-by-one, tens of thousands of times per second. Studying and enabling such high-speed phenomena pose enormous technical challenges. For one, parasitic capacitance inherent in analog electrical components limits their response time. Additionally, converting these fast analog signals to the digital domain requires enormous sampling speeds, which can lead to significant jitter and distortion. State-of-the-art imaging technologies, essential for studying biological dynamics and cells in flow, are limited in speed and sensitivity by finite charge transfer and read rates, and by the small numbers of photo-electrons accumulated in short integration times. And finally, ultra-high throughput real-time digital processing is required at the backend to analyze the streaming data. In this thesis, I discuss my work in developing real-time instruments, employing ultrafast optical techniques, which overcome some of these obstacles. In particular, I use broadband dispersive optics to slow down fast signals to speeds accessible to high-bit depth digitizers and signal processors. I also apply telecommunication multiplexing techniques to boost the speeds of confocal fluorescence microscopy. The photonic time stretcher (TiSER) uses dispersive Fourier transformation to slow down analog signals before digitization and

  12. Fast Rise Time and High Voltage Nanosecond Pulses at High Pulse Repetition Frequency

    NASA Astrophysics Data System (ADS)

    Miller, Kenneth E.; Ziemba, Timothy; Prager, James; Picard, Julian; Hashim, Akel

    2015-09-01

    Eagle Harbor Technologies (EHT), Inc. is conducting research to decrease the rise time and increase the output voltage of the EHT Nanosecond Pulser product line, which allows for independently, user-adjustable output voltage (0 - 20 kV), pulse width (20 - 500 ns), and pulse repetition frequency (0 - 100 kHz). The goals are to develop higher voltage pulses (50 - 60 kV), decrease the rise time from 20 to below 10 ns, and maintain the high pulse repetition capabilities. These new capabilities have applications to pseudospark generation, corona production, liquid discharges, and nonlinear transmission line driving for microwave production. This work is supported in part by the US Navy SBIR program.

  13. Development and fabrication of a high current, fast recovery power diode

    NASA Technical Reports Server (NTRS)

    Berman, A. H.; Balodis, V.; Devance, D. C.; Gaugh, C. E.; Karlsson, E. A.

    1983-01-01

    A high voltage (VR = 1200 V), high current (IF = 150 A), fast recovery ( 700 ns) and low forward voltage drop ( 1.5 V) silicon rectifier was designed and the process developed for its fabrication. For maximum purity, uniformity and material characteristic stability, neutron transmutation n-type doped float zone silicon is used. The design features a hexagonal chip for maximum area utilization of space available in the DO-8 diode package, PIN diffused junction structure with deep diffused D(+) anode and a shallow high concentration n(+) cathode. With the high temperature glass passivated positive bevel mesa junction termination, the achieved blocking voltage is close to the theoretical limit of the starting material. Gold diffusion is used to control the lifetime and the resulting effect on switching speed and forward voltage tradeoff. For solder reflow assembly, trimetal (Al-Ti-Ni) contacts are used. The required major device electrical characteristics were achieved. Due to the tradeoff nature of forward voltage drop and reverse recovery time, a compromise was reached for these values.

  14. Progressive FastICA Peel-Off and Convolution Kernel Compensation Demonstrate High Agreement for High Density Surface EMG Decomposition

    PubMed Central

    Chen, Maoqi

    2016-01-01

    Decomposition of electromyograms (EMG) is a key approach to investigating motor unit plasticity. Various signal processing techniques have been developed for high density surface EMG decomposition, among which the convolution kernel compensation (CKC) has achieved high decomposition yield with extensive validation. Very recently, a progressive FastICA peel-off (PFP) framework has also been developed for high density surface EMG decomposition. In this study, the CKC and PFP methods were independently applied to decompose the same sets of high density surface EMG signals. Across 91 trials of 64-channel surface EMG signals recorded from the first dorsal interosseous (FDI) muscle of 9 neurologically intact subjects, there were a total of 1477 motor units identified from the two methods, including 969 common motor units. On average, 10.6 ± 4.3 common motor units were identified from each trial, which showed a very high matching rate of 97.85 ± 1.85% in their discharge instants. The high degree of agreement of common motor units from the CKC and the PFP processing provides supportive evidence of the decomposition accuracy for both methods. The different motor units obtained from each method also suggest that combination of the two methods may have the potential to further increase the decomposition yield. PMID:27642525

  15. Progressive FastICA Peel-Off and Convolution Kernel Compensation Demonstrate High Agreement for High Density Surface EMG Decomposition.

    PubMed

    Chen, Maoqi; Holobar, Ales; Zhang, Xu; Zhou, Ping

    2016-01-01

    Decomposition of electromyograms (EMG) is a key approach to investigating motor unit plasticity. Various signal processing techniques have been developed for high density surface EMG decomposition, among which the convolution kernel compensation (CKC) has achieved high decomposition yield with extensive validation. Very recently, a progressive FastICA peel-off (PFP) framework has also been developed for high density surface EMG decomposition. In this study, the CKC and PFP methods were independently applied to decompose the same sets of high density surface EMG signals. Across 91 trials of 64-channel surface EMG signals recorded from the first dorsal interosseous (FDI) muscle of 9 neurologically intact subjects, there were a total of 1477 motor units identified from the two methods, including 969 common motor units. On average, 10.6 ± 4.3 common motor units were identified from each trial, which showed a very high matching rate of 97.85 ± 1.85% in their discharge instants. The high degree of agreement of common motor units from the CKC and the PFP processing provides supportive evidence of the decomposition accuracy for both methods. The different motor units obtained from each method also suggest that combination of the two methods may have the potential to further increase the decomposition yield.

  16. Development of the Fast Scintillation Detector with Programmable High Voltage Adjustment Suitable for Mössbauer Spectroscopy

    NASA Astrophysics Data System (ADS)

    Prochazka, R.; Pechousek, J.; Frydrych, J.

    2010-07-01

    This work is focused on a development of a compact fast scintillation detector suitable for Mössbauer spectroscopy (low energy X-ray/γ-ray detection) where high counting rates are inevitable. Optimization of this part was necessary for a reliable function, better time resolution and to avoid a detector pulses pile-up effect. The pile-up effect decreases the measurement performance, significantly depends on the source activity and also on the pulse duration. Our new detection unit includes a fast scintillation crystal YAP:Ce, an R6095 photomultiplier tube, a high voltage power supply socket C9028-01 assembly, an AD5252 digital potentiometer with an I2C interface and an AD8000 ultra fast operation preamplifier. The main advantages of this solution lie in a short pulse duration (less than 200 ns), stable operation for high activities, programmable gain of the high voltage supply and compact design in the aluminum housing.

  17. Fast, high-sensitivity, multipesticide analysis of complex mixtures with supersonic gas chromatography-mass spectrometry.

    PubMed

    Kochman, Maya; Gordin, Alexander; Goldshlag, Paulina; Lehotay, Steven J; Amnirav, Aviv

    2002-10-18

    We developed a new instrumental approach, termed Supersonic GC-MS, which achieves fast, sensitive, confirmatory and quantitative analysis of a broad range of pesticides in complex agricultural matrices. Our Supersonic GC-MS system is a modification of a bench-top Agilent 6890 GC+5972 MSD with a supersonic molecular beam (SMB) interface and fly-through EI ion source. One of the main advantages of Supersonic GC-MS is an enhanced molecular ion (M+) in the resulting mass spectra. For example, the M+ was observed in all 88 pesticides that we studied using the Supersonic GC-MS whereas only 36 of 63 (57%) pesticides that we investigated in standard GC-MS exhibited a M+. We also found that the degree of matrix interference is exponentially reduced with the fragment mass by about 20-fold per 100 amu increasing mass. The enhancement of the M+ combined with the reduction in matrix background noise permit rapid full scan analysis of a potentially unlimited number of pesticides, unlike selected ion monitoring or MS-MS in which specific conditions are required in segments for targeted pesticides. Furthermore, unlike the case with chemical ionization, EI-SMB-MS spectra still give accurate identification of compounds using common mass spectral libraries. In practice,we found thatlibraries favor mass spectra in which the M+ appears, thus Supersonic GC-MS produced better spectra for compound identification than standard GC-MS. To achieve even lower identification limits, the M+ plus a second major ion (still using full scan data) gives higher signal-to-chemical noise ratios than the traditional 3-ion approach. The replacement of two low-mass ions with the M+ (supersonic two-ions method) results in a significant reduction of matrix interference by a factor of up to 90. Another main advantage of Supersonic GC-MS is its exceptional suitability for fast GC-MS with high carrier gas flow-rate. Fast Supersonic GC-MS was able to analyze thermally labile pesticides, such as carbamates, that

  18. Towards Fast Morphological Mosaicking of High-Resolution Multi-Spectral Products - on Improvements of Seamlines

    NASA Astrophysics Data System (ADS)

    Storch, Tobias; Fischer, Peter; Fast, Sebastian; Serr, Philipp; Krauß, Thomas; Müller, Rupert

    2016-06-01

    The complex process of fully automatically establishing seamlines for the fast production of high-quality mosaics with high-amount of high-resolution multi-spectral images is detailed and improved in this paper. The algorithm is analyzed and a quasi-linear runtime in the number of considered pixels is proven for all situations. For typical situations the storage is even essentially smaller from a complexity theoretical perspective. Improvements from algorithm practical perspective are specified, too. The influence of different methods for the determination of seamlines based on gradients is investigated in detail for three Sentinel-2 products. The studied techniques cover well-known ones normally based on a single band. But also more sophisticated techniques based on multiple bands or even taking additional external geo-information data are taken into account. Based on the results a larger area covered by Image2006 orthorectified products with data of the Resourcesat-1 mission is regarded. The feasibility of applying advanced subordinated methods for improving the mosaic such as radiometric harmonization is examined. This also illustrates the robustness of the improved seamline determination approaches.

  19. IceCube constraints on fast-spinning pulsars as high-energy neutrino sources

    SciTech Connect

    Fang, Ke; Kotera, Kumiko; Murase, Kohta; Olinto, Angela V. E-mail: kotera@iap.fr E-mail: olinto@kicp.uchicago.edu

    2016-04-01

    Relativistic winds of fast-spinning pulsars have been proposed as a potential site for cosmic-ray acceleration from very high energies (VHE) to ultrahigh energies (UHE). We re-examine conditions for high-energy neutrino production, considering the interaction of accelerated particles with baryons of the expanding supernova ejecta and the radiation fields in the wind nebula. We make use of the current IceCube sensitivity in diffusive high-energy neutrino background, in order to constrain the parameter space of the most extreme neutron stars as sources of VHE and UHE cosmic rays. We demonstrate that the current non-observation of 10{sup 18} eV neutrinos put stringent constraints on the pulsar scenario. For a given model, birthrates, ejecta mass and acceleration efficiency of the magnetar sources can be constrained. When we assume a proton cosmic ray composition and spherical supernovae ejecta, we find that the IceCube limits almost exclude their significant contribution to the observed UHE cosmic-ray flux. Furthermore, we consider scenarios where a fraction of cosmic rays can escape from jet-like structures piercing the ejecta, without significant interactions. Such scenarios would enable the production of UHE cosmic rays and help remove the tension between their EeV neutrino production and the observational data.

  20. IceCube constraints on fast-spinning pulsars as high-energy neutrino sources

    NASA Astrophysics Data System (ADS)

    Fang, Ke; Kotera, Kumiko; Murase, Kohta; Olinto, Angela V.

    2016-04-01

    Relativistic winds of fast-spinning pulsars have been proposed as a potential site for cosmic-ray acceleration from very high energies (VHE) to ultrahigh energies (UHE). We re-examine conditions for high-energy neutrino production, considering the interaction of accelerated particles with baryons of the expanding supernova ejecta and the radiation fields in the wind nebula. We make use of the current IceCube sensitivity in diffusive high-energy neutrino background, in order to constrain the parameter space of the most extreme neutron stars as sources of VHE and UHE cosmic rays. We demonstrate that the current non-observation of 1018 eV neutrinos put stringent constraints on the pulsar scenario. For a given model, birthrates, ejecta mass and acceleration efficiency of the magnetar sources can be constrained. When we assume a proton cosmic ray composition and spherical supernovae ejecta, we find that the IceCube limits almost exclude their significant contribution to the observed UHE cosmic-ray flux. Furthermore, we consider scenarios where a fraction of cosmic rays can escape from jet-like structures piercing the ejecta, without significant interactions. Such scenarios would enable the production of UHE cosmic rays and help remove the tension between their EeV neutrino production and the observational data.

  1. Highly Crystalline CVD-grown Multilayer MoSe2 Thin Film Transistor for Fast Photodetector

    PubMed Central

    Jung, Chulseung; Kim, Seung Min; Moon, Hyunseong; Han, Gyuchull; Kwon, Junyeon; Hong, Young Ki; Omkaram, Inturu; Yoon, Youngki; Kim, Sunkook; Park, Jozeph

    2015-01-01

    Hexagonal molybdenum diselenide (MoSe2) multilayers were grown by chemical vapor deposition (CVD). A relatively high pressure (>760 Torr) was used during the CVD growth to achieve multilayers by creating multiple nuclei based on the two-dimensional crystal growth model. Our CVD-grown multilayer MoSe2 thin-film transistors (TFTs) show p-type-dominant ambipolar behaviors, which are attributed to the formation of Se vacancies generated at the decomposition temperature (650 °C) after the CVD growth for 10 min. Our MoSe2 TFT with a reasonably high field-effect mobility (10 cm2/V · s) exhibits a high photoresponsivity (93.7 A/W) and a fast photoresponse time (τrise ~ 0.4 s) under the illumination of light, which demonstrates the practical feasibility of multilayer MoSe2 TFTs for photodetector applications. PMID:26477744

  2. A 3D Chemically Modified Graphene Hydrogel for Fast, Highly Sensitive, and Selective Gas Sensor

    PubMed Central

    Wu, Jin; Tao, Kai; Guo, Yuanyuan; Li, Zhong; Wang, Xiaotian; Luo, Zhongzhen; Du, Chunlei; Chen, Di; Norford, Leslie K.

    2016-01-01

    Reduced graphene oxide (RGO) has proved to be a promising candidate in high‐performance gas sensing in ambient conditions. However, trace detection of different kinds of gases with simultaneously high sensitivity and selectivity is challenging. Here, a chemiresistor‐type sensor based on 3D sulfonated RGO hydrogel (S‐RGOH) is reported, which can detect a variety of important gases with high sensitivity, boosted selectivity, fast response, and good reversibility. The NaHSO3 functionalized RGOH displays remarkable 118.6 and 58.9 times higher responses to NO2 and NH3, respectively, compared with its unmodified RGOH counterpart. In addition, the S‐RGOH sensor is highly responsive to volatile organic compounds. More importantly, the characteristic patterns on the linearly fitted response–temperature curves are employed to distinguish various gases for the first time. The temperature of the sensor is elevated rapidly by an imbedded microheater with little power consumption. The 3D S‐RGOH is characterized and the sensing mechanisms are proposed. This work gains new insights into boosting the sensitivity of detecting various gases by combining chemical modification and 3D structural engineering of RGO, and improving the selectivity of gas sensing by employing temperature dependent response characteristics of RGO for different gases. PMID:28331786

  3. Simulation of high-energy proton production by fast magnetosonic shock waves in pinched plasma discharges

    NASA Astrophysics Data System (ADS)

    Mizuguchi, Yusuke; Sakai, Jun-Ichi; Yousefi, Hamid Reza; Haruki, Takayuki; Masugata, Katsumi

    2007-03-01

    High-energy particles of a few hundred keV for electrons and up to MeV for ions were observed in a plasma focus device. Haruki et al. [Phys. Plasmas 13, 082106-1 (2006)] studied the mechanism of high-energy particle production in pinched plasma discharges by use of a 3D relativistic and fully electromagnetic particle-in-cell code. It was found that the pinched current is unstable against a sausage instability, and then becomes unstable against a kink instability. As a result high-energy electrons were observed, but protons with MeV energies were not observed. In this paper the same pinch dynamics as Haruki and co-workers is investigated, focusing on the shock formation and the shock acceleration during the pinched current. It is found that a fast magnetosonic shock wave is produced during the pinching phase which, after the maximum pinch occurs, is strongly enhanced and propagates outwards. Some protons trapped in the electrostatic potential produced near the shock front can be accelerated to a few MeV by the surfatron acceleration mechanism. It is also found that the protons accelerated along the pinched axis have a ring-shaped angular distribution that is observed from numerous experiments.

  4. Fast Food Consumption Pattern and Its Association with Overweight Among High School Boys in Mangalore City of Southern India

    PubMed Central

    Nelliyanil, Maria; Rai, Sharada; Y.P., Raghavendra Babu; Kotian, Shashidhar M.; Ghosh, Tanima; Singh, Manisha

    2015-01-01

    Context Fast foods are quite popular among children owing to taste, appearance and hype created by mass media. However, the increased incidence of lifestyle disorders seen now-a-days at an early age could be attributed to fast foods. Aim This study was done to assess the awareness of health hazards, consumption pattern of fast foods and to find out its association with overweight among high school students. Settings and Design This cross-sectional study was done among boys of 3 private schools in Mangalore city in March 2012. Materials and Methods Data was collected using a semi-structured self-administered questionnaire. Statistical Analysis Chi-square test, one-way ANOVA and binary logistic regression analysis was used for analysis. P-value ≤ 0.05 was considered as statistically significant association. Results Mean age of boys was 13.5±0.9 years. Out of 300 participants, 41(13.7%) were overweight and 8 (2.7%) were obese. 292(97.3%) were fast food users of which 42(14.4%) consumed it every day. Majority of participants were introduced to fast foods through television commercials 193(64.3%). 73(57%) developed this habit as they were bored with home food. Awareness of harmful effects of fast food consumption was known to 186(62%) students and this was found to be associated with the perceived need to control its usage (p<0.001). Parental consumption of fast foods was found to influence fast food consumption among children (p=0.024). As many as 68(22.7%) and 206(68.7%) children were not eating vegetables and fruits respectively every day. Increased frequency of fast food consumption in a week was found to be associated with overweight or obesity among children after adjusting the effects of confounders (p=0.003). Conclusion Awareness on health hazards of fast foods needs to be taught at schools so as to minimize its consumption. Parents have to set an example themselves by not eating fast foods and improving home food to support discouragement of fast foods. This

  5. Fast Food Consumption Pattern and Its Association with Overweight Among High School Boys in Mangalore City of Southern India.

    PubMed

    Joseph, Nitin; Nelliyanil, Maria; Rai, Sharada; Y P, Raghavendra Babu; Kotian, Shashidhar M; Ghosh, Tanima; Singh, Manisha

    2015-05-01

    Fast foods are quite popular among children owing to taste, appearance and hype created by mass media. However, the increased incidence of lifestyle disorders seen now-a-days at an early age could be attributed to fast foods. This study was done to assess the awareness of health hazards, consumption pattern of fast foods and to find out its association with overweight among high school students. This cross-sectional study was done among boys of 3 private schools in Mangalore city in March 2012. Data was collected using a semi-structured self-administered questionnaire. Chi-square test, one-way ANOVA and binary logistic regression analysis was used for analysis. P-value ≤ 0.05 was considered as statistically significant association. Mean age of boys was 13.5±0.9 years. Out of 300 participants, 41(13.7%) were overweight and 8 (2.7%) were obese. 292(97.3%) were fast food users of which 42(14.4%) consumed it every day. Majority of participants were introduced to fast foods through television commercials 193(64.3%). 73(57%) developed this habit as they were bored with home food. Awareness of harmful effects of fast food consumption was known to 186(62%) students and this was found to be associated with the perceived need to control its usage (p<0.001). Parental consumption of fast foods was found to influence fast food consumption among children (p=0.024). As many as 68(22.7%) and 206(68.7%) children were not eating vegetables and fruits respectively every day. Increased frequency of fast food consumption in a week was found to be associated with overweight or obesity among children after adjusting the effects of confounders (p=0.003). Awareness on health hazards of fast foods needs to be taught at schools so as to minimize its consumption. Parents have to set an example themselves by not eating fast foods and improving home food to support discouragement of fast foods. This would minimize life style disorders among children to a greater extent.

  6. [Burden of disease attributable to high fasting plasma glucose in 1990 and 2013 in China].

    PubMed

    Zhao, Y F; Wang, Z Q; Yang, J; Li, Y C; Yin, P; You, J L; Zhou, M G

    2016-09-06

    Objective: To analyze the burden of disease attributed to high fasting plasma glucose(FPG)in China in 1990 and 2013. Methods: The analysis used data obtained from the 2013 Global Burden of Diseases Study and examined deaths, death rate, disability-adjusted life years(DALY), years lived with disability(YLD)and years of life lost(YLL)attributed to high FPG in 1990 and 2013 in China(not including Taiwan, China). An average world population age-structure for the period 2000- 2025 was adopted to calculate age-standardized rates. Results: In 2013, the number of deaths attributed to high FPG in China increased to 621.9 thousand from 320.3 thousand in 1990. From 1990- 2013, the age-standardized death rate attributable to high FPG increased from 45.69/100 000 to 48.64/100 000. DALYs caused by high FPG increased to 20.389 1 million in 2013 from 10.648 3 million in 1990. In 2013, high FPG caused 8.751 5 million YLD and 11.637 6 million YLL, and the percentage of YLL in DALY decreased to 57.1% in 2013 from 68.7% in 1990. Compared with 1990, the age-standardized DALY rate attributed to high FPG increased by 10.81%. In 2013, the top three provinces with the highest burden of disease attributed to high FPG were Xinjiang, Jilin and Liaoning provinces, with standardized death rates of 83.38, 74.01 and 68.64/100 000, respectively, and the standardized DALY rate was 2 217.96, 2 001.84 and 1 837.79/100 000 in the three provinces, respectively. Conclusion: Compared with 1990, the burden of disease attributed to high FPG in 2013 increased substantially in China, in particular the burden of attributed YLD. However, the burden of YLL attributed to high FPG has decreased modestly. The burden of disease caused by high FPG shows variation among different provinces in China.

  7. Evaluation of high performance data acquisition boards for simultaneous sampling of fast signals from PET detectors

    NASA Astrophysics Data System (ADS)

    Judenhofer, Martin S.; Pichler, Bernd J.; Cherry, Simon R.

    2005-01-01

    Detectors used for positron emission tomography (PET) provide fast, randomly distributed signals that need to be digitized for further processing. One possibility is to sample the signals at the peak initiated by a trigger from a constant fraction discriminator (CFD). For PET detectors, simultaneous acquisition of many channels is often important. To develop and evaluate novel PET detectors, a flexible, relatively low cost and high performance laboratory data acquisition (DAQ) system is therefore required. The use of dedicated DAQ systems, such as a multi-channel analysers (MCAs) or continuous sampling boards at high rates, is expensive. This work evaluates the suitability of well-priced peripheral component interconnect (PCI)-based 8-channel DAQ boards (PD2-MFS-8 2M/14 and PD2-MFS-8-500k/14, United Electronic Industries Inc., Canton, MA, USA) for signal acquisition from novel PET detectors. A software package was developed to access the board, measure basic board parameters, and to acquire, visualize, and analyse energy spectra and position profiles from block detectors. The performance tests showed that the boards input linearity is >99.2% and the standard deviation is <9 mV at 10 V for constant signals. Synchronous sampling of multiple channels and external synchronization of more boards are possible at rates up to 240 kHz per channel. Signals with rise times as fast as 130 ns (<2 V amplitude) can be acquired without slew rate effects. However, for signals with amplitudes of up to 5 V, a rise time slower than 250 ns is required. The measured energy resolution of a lutetium oxyorthosilicate (LSO)-photomultiplier tube (PMT) detector with a 22Na source was 14.9% (FWHM) at 511 keV and is slightly better than the result obtained with a high-end single channel MCA (8000A, Amptek, USA) using the same detector (16.8%). The crystals (1.2 × 1.2 × 12 mm3) within a 9 × 9 LSO block detector could be clearly separated in an acquired position profile. Thus, these boards are

  8. Determinants of High Fasting Insulin and Insulin Resistance Among Overweight/Obese Adolescents

    PubMed Central

    Ling, Jerri Chiu Yun; Mohamed, Mohd Nahar Azmi; Jalaludin, Muhammad Yazid; Rampal, Sanjay; Zaharan, Nur Lisa; Mohamed, Zahurin

    2016-01-01

    Hyperinsulinaemia is the earliest subclinical metabolic abnormality, which precedes insulin resistance in obese children. An investigation was conducted on the potential predictors of fasting insulin and insulin resistance among overweight/obese adolescents in a developing Asian country. A total of 173 overweight/obese (BMI > 85th percentile) multi-ethnic Malaysian adolescents aged 13 were recruited from 23 randomly selected schools in this cross-sectional study. Waist circumference (WC), body fat percentage (BF%), physical fitness score (PFS), fasting glucose and fasting insulin were measured. Insulin resistance was calculated using homeostasis model assessment of insulin resistance (HOMA-IR). Adjusted stepwise multiple regression analysis was performed to predict fasting insulin and HOMA-IR. Covariates included pubertal stage, socioeconomic status, nutritional and physical activity scores. One-third of our adolescents were insulin resistant, with girls having significantly higher fasting insulin and HOMA-IR than boys. Gender, pubertal stage, BMI, WC and BF% had significant, positive moderate correlations with fasting insulin and HOMA-IR while PFS was inversely correlated (p < 0.05). Fasting insulin was primarily predicted by gender-girls (Beta = 0.305, p < 0.0001), higher BMI (Beta = −0.254, p = 0.02) and greater WC (Beta = 0.242, p = 0.03). This study demonstrated that gender, BMI and WC are simple predictors of fasting insulin and insulin resistance in overweight/obese adolescents. PMID:27824069

  9. High-speed optical shutter coupled to fast-readout CCD camera

    NASA Astrophysics Data System (ADS)

    Yates, George J.; Pena, Claudine R.; McDonald, Thomas E., Jr.; Gallegos, Robert A.; Numkena, Dustin M.; Turko, Bojan T.; Ziska, George; Millaud, Jacques E.; Diaz, Rick; Buckley, John; Anthony, Glen; Araki, Takae; Larson, Eric D.

    1999-04-01

    A high frame rate optically shuttered CCD camera for radiometric imaging of transient optical phenomena has been designed and several prototypes fabricated, which are now in evaluation phase. the camera design incorporates stripline geometry image intensifiers for ultra fast image shutters capable of 200ps exposures. The intensifiers are fiber optically coupled to a multiport CCD capable of 75 MHz pixel clocking to achieve 4KHz frame rate for 512 X 512 pixels from simultaneous readout of 16 individual segments of the CCD array. The intensifier, Philips XX1412MH/E03 is generically a Generation II proximity-focused micro channel plate intensifier (MCPII) redesigned for high speed gating by Los Alamos National Laboratory and manufactured by Philips Components. The CCD is a Reticon HSO512 split storage with bi-direcitonal vertical readout architecture. The camera main frame is designed utilizing a multilayer motherboard for transporting CCD video signals and clocks via imbedded stripline buses designed for 100MHz operation. The MCPII gate duration and gain variables are controlled and measured in real time and up-dated for data logging each frame, with 10-bit resolution, selectable either locally or by computer. The camera provides both analog and 10-bit digital video. The camera's architecture, salient design characteristics, and current test data depicting resolution, dynamic range, shutter sequences, and image reconstruction will be presented and discussed.

  10. Fast coding unit selection method for high efficiency video coding intra prediction

    NASA Astrophysics Data System (ADS)

    Xiong, Jian

    2013-07-01

    The high efficiency video coding (HEVC) video coding standard under development can achieve higher compression performance than previous standards, such as MPEG-4, H.263, and H.264/AVC. To improve coding performance, a quad-tree coding structure and a robust rate-distortion (RD) optimization technique is used to select an optimum coding mode. Since the RD costs of all possible coding modes are computed to decide an optimum mode, high computational complexity is induced in the encoder. A fast learning-based coding unit (CU) size selection method is presented for HEVC intra prediction. The proposed algorithm is based on theoretical analysis that shows the non-normalized histogram of oriented gradient (n-HOG) can be used to help select CU size. A codebook is constructed offline by clustering n-HOGs of training sequences for each CU size. The optimum size is determined by comparing the n-HOG of the current CU with the learned codebooks. Experimental results show that the CU size selection scheme speeds up intra coding significantly with negligible loss of peak signal-to-noise ratio.

  11. Can Nanofluidic Chemical Release Enable Fast, High Resolution Neurotransmitter-Based Neurostimulation?

    PubMed Central

    Jones, Peter D.; Stelzle, Martin

    2016-01-01

    Artificial chemical stimulation could provide improvements over electrical neurostimulation. Physiological neurotransmission between neurons relies on the nanoscale release and propagation of specific chemical signals to spatially-localized receptors. Current knowledge of nanoscale fluid dynamics and nanofluidic technology allows us to envision artificial mechanisms to achieve fast, high resolution neurotransmitter release. Substantial technological development is required to reach this goal. Nanofluidic technology—rather than microfluidic—will be necessary; this should come as no surprise given the nanofluidic nature of neurotransmission. This perspective reviews the state of the art of high resolution electrical neuroprostheses and their anticipated limitations. Chemical release rates from nanopores are compared to rates achieved at synapses and with iontophoresis. A review of microfluidic technology justifies the analysis that microfluidic control of chemical release would be insufficient. Novel nanofluidic mechanisms are discussed, and we propose that hydrophobic gating may allow control of chemical release suitable for mimicking neurotransmission. The limited understanding of hydrophobic gating in artificial nanopores and the challenges of fabrication and large-scale integration of nanofluidic components are emphasized. Development of suitable nanofluidic technology will require dedicated, long-term efforts over many years. PMID:27065794

  12. Fast Solutions of Maxwell's Equation for High Resolution Electromagnetic Imaging of Transport Pathways

    SciTech Connect

    DAY,DAVID M.; NEWMAN,GREGORY A.

    1999-10-01

    A fast precondition technique has been developed which accelerates the finite difference solutions of the 3D Maxwell's equations for geophysical modeling. The technique splits the electric field into its curl free and divergence free projections, and allows for the construction of an inverse operator. Test examples show an order of magnitude speed up compared with a simple Jacobi preconditioner. Using this preconditioner a low frequency Neumann series expansion is developed and used to compute responses at multiple frequencies very efficiently. Simulations requiring responses at multiple frequencies, show that the Neumann series is faster than the preconditioned solution, which must compute solutions at each discrete frequency. A Neumann series expansion has also been developed in the high frequency limit along with spectral Lanczos methods in both the high and low frequency cases for simulating multiple frequency responses with maximum efficiency. The research described in this report was to have been carried out over a two-year period. Because of communication difficulties, the project was funded for first year only. Thus the contents of this report are incomplete with respect to the original project objectives.

  13. Fast high resolution reconstruction in multi-slice and multi-view cMRI

    NASA Astrophysics Data System (ADS)

    Velasco Toledo, Nelson; Romero Castro, Eduardo

    2015-01-01

    Cardiac magnetic resonance imaging (cMRI) is an useful tool in diagnosis, prognosis and research since it functionally tracks the heart structure. Although useful, this imaging technique is limited in spatial resolution because heart is a constant moving organ, also there are other non controled conditions such as patient movements and volumetric changes during apnea periods when data is acquired, those conditions limit the time to capture high quality information. This paper presents a very fast and simple strategy to reconstruct high resolution 3D images from a set of low resolution series of 2D images. The strategy is based on an information reallocation algorithm which uses the DICOM header to relocate voxel intensities in a regular grid. An interpolation method is applied to fill empty places with estimated data, the interpolation resamples the low resolution information to estimate the missing information. As a final step a gaussian filter that denoises the final result. A reconstructed image evaluation is performed using as a reference a super-resolution reconstructed image. The evaluation reveals that the method maintains the general heart structure with a small loss in detailed information (edge sharpening and blurring), some artifacts related with input information quality are detected. The proposed method requires low time and computational resources.

  14. High-fidelity, broadband stimulated-Brillouin-scattering-based slow light using fast noise modulation.

    PubMed

    Zhu, Yunhui; Lee, Myungjun; Neifeld, Mark A; Gauthier, Daniel J

    2011-01-17

    We demonstrate a 5-GHz-broadband tunable slow-light device based on stimulated Brillouin scattering in a standard highly-nonlinear optical fiber pumped by a noise-current-modulated laser beam. The noisemodulation waveform uses an optimized pseudo-random distribution of the laser drive voltage to obtain an optimal flat-topped gain profile, which minimizes the pulse distortion and maximizes pulse delay for a given pump power. In comparison with a previous slow-modulation method, eye-diagram and signal-to-noise ratio (SNR) analysis show that this broadband slow-light technique significantly increases the fidelity of a delayed data sequence, while maintaining the delay performance. A fractional delay of 0.81 with a SNR of 5.2 is achieved at the pump power of 350 mW using a 2-km-long highly nonlinear fiber with the fast noise-modulation method, demonstrating a 50% increase in eye-opening and a 36% increase in SNR in the comparison.

  15. Fast critical assembly safeguards: NDA methods for highly enriched uranium. Summary report, October 1978-September 1979

    SciTech Connect

    Bellinger, F.O.; Winslow, G.H.

    1980-12-01

    Nondestructive assay (NDA) methods, principally passive gamma measurements and active neutron interrogation, have been studied for their safeguards effectiveness and programmatic impact as tools for making inventories of highly enriched uranium fast critical assembly fuel plates. It was concluded that no NDA method is the sole answer to the safeguards problem, that each of those emphasized here has its place in an integrated safeguards system, and that each has minimum facility impact. It was found that the 185-keV area, as determined with a NaI detector, was independent of highly-enriched uranium (HEU) plate irradiation history, though the random neutron driver methods used here did not permit accurate assay of irradiated plates. Containment procedures most effective for accurate assaying were considered, and a particular geometry is recommended for active interrogation by a random driver. A model, pertinent to that geometry, which relates the effects of multiplication and self-absorption, is described. Probabilities of failing to detect that plates are missing are examined.

  16. Fast neutron irradiation of high- Tc superconducting materials engineered for magnetic field and THz photon detection

    NASA Astrophysics Data System (ADS)

    Gozzelino, Laura; Gerbaldo, Roberto; Ghigo, Gianluca; Laviano, Francesco; Mezzetti, Enrica; Cherubini, Roberto; Minetti, Bruno

    2012-02-01

    Radiation-hard sensors are at present time highly requested for applications in environments with potential radiation hazard such as space, accelerators and fusion machines. We developed device prototypes for magnetic field and THz photon detection, both based on YBa 2Cu 3O 7-x (YBCO) superconducting films locally nanostructured by means of 0.25 GeV Au-ion lithography. This micro-collimated implantation of high-density columnar defects in YBCO films allows localizing external electromagnetic excitations by means of dissipative signals only induced into the nanostructured regions. The radiation hardness of detector prototypes was checked under fast neutron radiation. It turns out that, up to a neutron fluence comparable with those expected for 10 years long permanence in the space, no significant change was detected in superconductor characteristics such as zero-field resistance-temperature or magneto-resistance, whose variations could dramatically affect device figures of merit as responsivity or noise equivalent power. Fluences and energy spectrum of the neutrons impinging on the sensor prototypes were determined by a Monte-Carlo code implemented "ad hoc".

  17. Fast reconfiguration of high-frequency brain networks in response to surprising changes in auditory input.

    PubMed

    Nicol, Ruth M; Chapman, Sandra C; Vértes, Petra E; Nathan, Pradeep J; Smith, Marie L; Shtyrov, Yury; Bullmore, Edward T

    2012-03-01

    How do human brain networks react to dynamic changes in the sensory environment? We measured rapid changes in brain network organization in response to brief, discrete, salient auditory stimuli. We estimated network topology and distance parameters in the immediate central response period, <1 s following auditory presentation of standard tones interspersed with occasional deviant tones in a mismatch-negativity (MMN) paradigm, using magnetoencephalography (MEG) to measure synchronization of high-frequency (gamma band; 33-64 Hz) oscillations in healthy volunteers. We found that global small-world parameters of the networks were conserved between the standard and deviant stimuli. However, surprising or unexpected auditory changes were associated with local changes in clustering of connections between temporal and frontal cortical areas and with increased interlobar, long-distance synchronization during the 120- to 250-ms epoch (coinciding with the MMN-evoked response). Network analysis of human MEG data can resolve fast local topological reconfiguration and more long-range synchronization of high-frequency networks as a systems-level representation of the brain's immediate response to salient stimuli in the dynamically changing sensory environment.

  18. A fast high-resolution track trigger for the H1 experiment

    NASA Astrophysics Data System (ADS)

    Naumann, J.; Baird, A.; Elsen, E.; Fleming, Y. H.; Kolander, M.; Kolya, S.; Meer, D.; Mercer, D.; Newman, P. R.; Sankey, D.; Schoning, A.; Schultz-Coulon, H.-C.; Wissing, C.

    2001-08-01

    After 2001, the upgraded ep collider HERA will provide an about five times higher luminosity for the two experiments H1 and ZEUS. To cope with the expected higher event rates, the H1 collaboration is building a track-based trigger system, the Fast Track Trigger (FTT). It will be integrated in the first three levels (L1-L3) of the H1 trigger scheme to provide higher selectivity for events with charged particles. The FTT will allow reconstruction of three-dimensional tracks in the central drift chamber down to 100 MeV/c within the L2 latency of /spl sim/23 /spl mu/s. To reach the necessary momentum resolution of /spl sim/5% (at 1 GeV/c), sophisticated reconstruction algorithms have to be implemented using high-density field-programmable gate arrays and their embedded content addressable memories. The final track parameter optimization will be done using noniterative fits implemented in digital signal processors. While at the first trigger level rough track information will be provided, at L2 tracks with high resolution are available to form trigger decisions on topological and other track-based criteria like multiplicities and momenta. At the third trigger level, a farm of commercial processor boards will be used to compute physics quantities such as invariant masses.

  19. High Brightness Gamma-Ray Production at Fermilab Accelerator Science and Technology (FAST) Facility

    SciTech Connect

    Mihalcea, Daniel; Jacobson, B.; Murokh, A.; Piiot, P.; Ruan, J.

    2016-10-10

    Electron beams with energies of the order of a few 100’s of MeV and low transverse emittance, in combination with powerful infrared lasers, allow for the production of high quality gamma rays through Inverse Compton Scattering (ICS). At Fermilab Accelerator Science and Technology (FAST) facility, a 300 MeV beam will be used to generate gamma rays with maximum photon energies of up to ∼ 1.5 MeV and brightness of the order of 1021 photons/[s-(mm-mrad)2- 0.1%BW]. Due to the low electron-beam transverse emittance, the relative bandwidth of the scattered radiation is expected to be ≤ 1%. A key challenge toward the production of high radiation dose and brightness is to enhance the energy of the infrared 3 ps laser pulses to the joule level. In this contribution, we present the plans for the experimental setup, along with comprehensive numerical simulations of the ICS process.

  20. High Tg and fast curing epoxy-based anisotropic conductive paste for electronic packaging

    NASA Astrophysics Data System (ADS)

    Keeratitham, Waralee; Somwangthanaroj, Anongnat

    2016-03-01

    Herein, our main objective is to prepare the fast curing epoxy system with high glass transition temperature (Tg) by incorporating the multifunctional epoxy resin into the mixture of diglycidyl ether of bisphenol A (DGEBA) as a major epoxy component and aromatic diamine as a hardener. Furthermore, the curing behavior as well as thermal and thermomechanical properties were investigated by differential scanning calorimetry (DSC), dynamic mechanical analysis (DMA) and thermomechanical analysis (TMA). It was found that Tg obtained from tan δ of DGEBA/aromatic diamine system increased from 100 °C to 205 °C with the presence of 30 percentage by weight of multifunctional epoxy resin. Additionally, the isothermal DSC results showed that the multifunctional epoxy resin can accelerate the curing reaction of DGEBA/aromatic diamine system. Namely, a high degree of curing (˜90%) was achieved after a few minutes of curing at low temperature of 130 °C, owing to a large number of epoxy ring of multifunctional epoxy resin towards the active hydrogen atoms of aromatic diamine.

  1. Nanometal-decorated exfoliated graphite nanoplatelet based glucose biosensors with high sensitivity and fast response.

    PubMed

    Lu, Jue; Do, Inhwan; Drzal, Lawrence T; Worden, Robert M; Lee, Ilsoon

    2008-09-23

    We report the novel fabrication of a highly sensitive, selective, fast responding, and affordable amperometric glucose biosensor using exfoliated graphite nanoplatelets (xGnPs) decorated with Pt and Pd nanoparticles. Nafion was used to solubilize metal-decorated graphite nanoplatelets, and a simple cast method with high content organic solvent (85 wt %) was used to prepare the biosensors. The addition of precious metal nanoparticles such as platinum (Pt) and palladium (Pd) to xGnP increased the electroactive area of the electrode and substantially decreased the overpotential in the detection of hydrogen peroxide. The Pt-xGnP glucose biosensor had a sensitivity of 61.5+/-0.6 microA/(mM x cm(2)) and gave a linear response up to 20 mM. The response time and detection limit (S/N=3) were determined to be 2 s and 1 microM, respectively. Therefore, this novel glucose biosensor based on the Pt nanoparticle coated xGnP is among the best reported to date in both sensing performance and production cost. In addition, the effects of metal nanoparticle loading and the particle size on the biosensor performance were systematically investigated.

  2. High-resolution, high-sensitivity, ground-based solar spectropolarimetry with a new fast imaging polarimeter. I. Prototype characterization

    NASA Astrophysics Data System (ADS)

    Iglesias, F. A.; Feller, A.; Nagaraju, K.; Solanki, S. K.

    2016-05-01

    Context. Remote sensing of weak and small-scale solar magnetic fields is of utmost relevance when attempting to respond to a number of important open questions in solar physics. This requires the acquisition of spectropolarimetric data with high spatial resolution (~10-1 arcsec) and low noise (10-3 to 10-5 of the continuum intensity). The main limitations to obtain these measurements from the ground, are the degradation of the image resolution produced by atmospheric seeing and the seeing-induced crosstalk (SIC). Aims: We introduce the prototype of the Fast Solar Polarimeter (FSP), a new ground-based, high-cadence polarimeter that tackles the above-mentioned limitations by producing data that are optimally suited for the application of post-facto image restoration, and by operating at a modulation frequency of 100 Hz to reduce SIC. Methods: We describe the instrument in depth, including the fast pnCCD camera employed, the achromatic modulator package, the main calibration steps, the effects of the modulation frequency on the levels of seeing-induced spurious signals, and the effect of the camera properties on the image restoration quality. Results: The pnCCD camera reaches 400 fps while keeping a high duty cycle (98.6%) and very low noise (4.94 e- rms). The modulator is optimized to have high (>80%) total polarimetric efficiency in the visible spectral range. This allows FSP to acquire 100 photon-noise-limited, full-Stokes measurements per second. We found that the seeing induced signals that are present in narrow-band, non-modulated, quiet-sun measurements are (a) lower than the noise (7 × 10-5) after integrating 7.66 min, (b) lower than the noise (2.3 × 10-4) after integrating 1.16 min and (c) slightly above the noise (4 × 10-3) after restoring case (b) by means of a multi-object multi-frame blind deconvolution. In addition, we demonstrate that by using only narrow-band images (with low S/N of 13.9) of an active region, we can obtain one complete set of high

  3. Gluconeogenesis is associated with high rates of tricarboxylic acid and pyruvate cycling in fasting northern elephant seals.

    PubMed

    Champagne, Cory D; Houser, Dorian S; Fowler, Melinda A; Costa, Daniel P; Crocker, Daniel E

    2012-08-01

    Animals that endure prolonged periods of food deprivation preserve vital organ function by sparing protein from catabolism. Much of this protein sparing is achieved by reducing metabolic rate and suppressing gluconeogenesis while fasting. Northern elephant seals (Mirounga angustirostris) endure prolonged fasts of up to 3 mo at multiple life stages. During these fasts, elephant seals maintain high levels of activity and energy expenditure associated with breeding, reproduction, lactation, and development while maintaining rates of glucose production typical of a postabsorptive mammal. Therefore, we investigated how fasting elephant seals meet the requirements of glucose-dependent tissues while suppressing protein catabolism by measuring the contribution of glycogenolysis, glycerol, and phosphoenolpyruvate (PEP) to endogenous glucose production (EGP) during their natural 2-mo postweaning fast. Additionally, pathway flux rates associated with the tricarboxylic acid (TCA) cycle were measured specifically, flux through phosphoenolpyruvate carboxykinase (PEPCK) and pyruvate cycling. The rate of glucose production decreased during the fast (F(1,13) = 5.7, P = 0.04) but remained similar to that of postabsorptive mammals. The fractional contributions of glycogen, glycerol, and PEP did not change with fasting; PEP was the primary gluconeogenic precursor and accounted for ∼95% of EGP. This large contribution of PEP to glucose production occurred without substantial protein loss. Fluxes through the TCA cycle, PEPCK, and pyruvate cycling were higher than reported in other species and were the most energetically costly component of hepatic carbohydrate metabolism. The active pyruvate recycling fluxes detected in elephant seals may serve to rectify gluconeogeneic PEP production during restricted anaplerotic inflow in these fasting-adapted animals.

  4. High-speed, multi-channel detector readout electronics for fast radiation detectors

    SciTech Connect

    Hennig, Wolfgang

    2012-06-22

    In this project, we are developing a high speed digital spectrometer that a) captures detector waveforms at rates up to 500 MSPS b) has upgraded event data acquisition with additional data buffers for zero dead time operation c) moves energy calculations to the FPGA to increase spectrometer throughput in fast scintillator applications d) uses a streamlined architecture and high speed data interface for even faster readout to the host PC These features are in addition to the standard functions in our existing spectrometers such as digitization, programmable trigger and energy filters, pileup inspection, data acquisition with energy and time stamps, MCA histograms, and run statistics. In Phase I, we upgraded one of our existing spectrometer designs to demonstrate the key principle of fast waveform capture using a 500 MSPS, 12 bit ADC and a Xilinx Virtex-4 FPGA. This upgraded spectrometer, named P500, performed well in initial tests of energy resolution, pulse shape analysis, and timing measurements, thus achieving item (a) above. In Phase II, we are revising the P500 to build a commercial prototype with the improvements listed in items (b)-(d). As described in the previous report, two devices were built to pursue this goal, named the Pixie-500 and the Pixie-500 Express. The Pixie-500 has only minor improvements from the Phase I prototype and is intended as an early commercial product (its production and part of its development were funded outside the SBIR). It also allows testing of the ADC performance in real applications.The Pixie-500 Express (or Pixie-500e) includes all of the improvements (b)-(d). At the end of Phase II of the project, we have tested and debugged the hardware, firmware and software of the Pixie-500 Express prototype boards delivered 12/3/2010. This proved substantially more complex than anticipated. At the time of writing, all hardware bugs have been fixed, the PCI Express interface is working, the SDRAM has been successfully tested and the SHARC

  5. Fast Mean-Shift Based Classification of Very High Resolution Images: Application to Forest Cover Mapping

    NASA Astrophysics Data System (ADS)

    Boukir, S.; Jones, S.; Reinke, K.

    2012-07-01

    This paper presents a new unsupervised classification method which aims to effectively and efficiently map remote sensing data. The Mean-Shift (MS) algorithm, a non parametric density-based clustering technique, is at the core of our method. This powerful clustering algorithm has been successfully used for both the classification and the segmentation of gray scale and color images during the last decade. However, very little work has been reported regarding the performance of this technique on remotely sensed images. The main disadvantage of the MS algorithm lies on its high computational costs. Indeed, it is based on an optimization procedure to determine the modes of the pixels density. To investigate the MS algorithm in the difficult context of very high resolution remote sensing imagery, we use a fast version of this algorithm which has been recently proposed, namely the Path-Assigned Mean Shift (PAMS). This algorithm is up to 5 times faster than other fast MS algorithms while inducing a low loss in quality compared to the original MS version. To compensate for this loss, we propose to use the K modes (cluster centroids) obtained after convergence of the PAMS algorithm as an initialization of a K-means clustering algorithm. The latter converges very quickly to a refined solution to the underlying clustering problem. Furthermore, it does not suffer the main drawback of the classic K-means algorithm (the number of clusters K needs to be specified) as K is automatically determined via the MS mode-seeking procedure. We demonstrate the effectiveness of this two-stage clustering method in performing automatic classification of aerial forest images. Both individual bands and band combination trails are presented. When compared to the classical PAMS algorithm, our technique is better in terms of classification quality. The improvement in classification is significant both visually and statistically. The whole classification process is performed in a few seconds on

  6. DOSIMETRIC EVALUATION OF LASER-DRIVEN X-RAY AND NEUTRON SOURCES UTILIZING XG-III PS LASER WITH PEAK POWER OF 300 TERAWATT.

    PubMed

    Yang, Bo; Qiu, Rui; Jiao, Jinlong; Lu, Wei; Zhang, Zhimeng; Zhou, Weimin; Ma, Chi; Zhang, Hui; Li, Junli

    2017-04-13

    Current short-pulse high-intensity lasers can accelerate electrons and proton/ions to energies of giga-electron volts. For certain advanced applications, laser-accelerated electrons and protons are optimised for high-energy X-ray and neutron generation at the XG-III picosecond (ps) laser beamline. These energetic X-ray and neutron beams can significantly affect radiation safety at the facility; therefore, proper evaluation of the radiological hazards induced by laser-driven X-ray and neutron sources is required. This study presents a dosimetric evaluation of laser-driven X-ray and neutron sources at the XG-III ps laser beamline. The 'source terms' of the laser-accelerated electrons and protons are characterised utilising the particle-in-cell method and an analytical model, respectively. The Monte Carlo code FLUKA is used to calculate prompt and residual dose yields due to all radiation field components and the number of residual activated nuclei. Our results can provide a reference for radiation hazard analysis at short-pulse high-intensity laser facilities worldwide. © The Author 2017. Published by Oxford University Press. All rights reserved. For Permissions, please email: journals.permissions@oup.com.

  7. Fast nanotopography imaging using a high speed cantilever with integrated heater-thermometer.

    PubMed

    Lee, Byeonghee; Somnath, Suhas; King, William P

    2013-04-05

    This paper presents a high speed tapping cantilever with an integrated heater-thermometer for fast nanotopography imaging. The cantilever is much smaller and faster than previous heated cantilevers, with a length of 35 μm and a resonant frequency of 1.4 MHz. The mechanical response time is characterized by scanning over a backward-facing step of height 20 nm. The mechanical response time is 77 μs in air and 448 μs in water, which compares favorably to the fastest commercial cantilevers that do not have integrated heaters. The doped silicon cantilever is designed with an integrated heater that can heat and cool in about 10 μs and can operate in both air and water. We demonstrate standard laser-based topography imaging along with thermal topography imaging, when the cantilever is actuated via the piezoelectric shaker in an atomic force microscope system and when it is actuated by Lorentz forces. The cantilever can perform thermal topography imaging in tapping mode with an imaging resolution of 7 nm at a scan speed of 1.46 mm s(-1).

  8. Development of fast heating electron beam annealing setup for ultra high vacuum chamber.

    PubMed

    Das, Sadhan Chandra; Majumdar, Abhijit; Katiyal, Sumant; Shripathi, T; Hippler, R

    2014-02-01

    We report the design and development of a simple, electrically low powered and fast heating versatile electron beam annealing setup (up to 1000 °C) working with ultra high vacuum (UHV) chamber for annealing thin films and multilayer structures. The important features of the system are constant temperature control in UHV conditions for the temperature range from room temperature to 1000 ºC with sufficient power of 330 W, at constant vacuum during annealing treatment. It takes approximately 6 min to reach 1000 °C from room temperature (∼10(-6) mbar) and 45 min to cool down without any extra cooling. The annealing setup consists of a UHV chamber, sample holder, heating arrangement mounted on suitable UHV electrical feed-through and electronic control and feedback systems to control the temperature within ±1 ºC of set value. The outside of the vacuum chamber is cooled by cold air of 20 °C of air conditioning machine used for the laboratory, so that chamber temperature does not go beyond 50 °C when target temperature is maximum. The probability of surface oxidation or surface contamination during annealing is examined by means of x-ray photoelectron spectroscopy of virgin Cu sample annealed at 1000 °C.

  9. A fast atlas-guided high density diffuse optical tomography system for brain imaging

    NASA Astrophysics Data System (ADS)

    Dai, Xianjin; Zhang, Tao; Yang, Hao; Jiang, Huabei

    2017-02-01

    Near infrared spectroscopy (NIRS) is an emerging functional brain imaging tool capable of assessing cerebral concentrations of oxygenated hemoglobin (HbO) and deoxygenated hemoglobin (HbR) during brain activation noninvasively. As an extension of NIRS, diffuse optical tomography (DOT) not only shares the merits of providing continuous readings of cerebral oxygenation, but also has the ability to provide spatial resolution in the millimeter scale. Based on the scattering and absorption properties of nonionizing near-infrared light in biological tissue, DOT has been successfully applied in the imaging of breast tumors, osteoarthritis and cortex activations. Here, we present a state-of-art fast high density DOT system suitable for brain imaging. It can achieve up to a 21 Hz sampling rate for a full set of two-wavelength data for 3-D DOT brain image reconstruction. The system was validated using tissue-mimicking brain-model phantom. Then, experiments on healthy subjects were conducted to demonstrate the capability of the system.

  10. Adipose Tissue CLK2 Promotes Energy Expenditure during High-Fat Diet Intermittent Fasting.

    PubMed

    Hatting, Maximilian; Rines, Amy K; Luo, Chi; Tabata, Mitsuhisa; Sharabi, Kfir; Hall, Jessica A; Verdeguer, Francisco; Trautwein, Christian; Puigserver, Pere

    2017-02-07

    A promising approach to treating obesity is to increase diet-induced thermogenesis in brown adipose tissue (BAT), but the regulation of this process remains unclear. Here we find that CDC-like kinase 2 (CLK2) is expressed in BAT and upregulated upon refeeding. Mice lacking CLK2 in adipose tissue exhibit exacerbated obesity and decreased energy expenditure during high-fat diet intermittent fasting. Additionally, tissue oxygen consumption and protein levels of UCP1 are reduced in CLK2-deficient BAT. Phosphorylation of CREB, a transcriptional activator of UCP1, is markedly decreased in BAT cells lacking CLK2 due to enhanced CREB dephosphorylation. Mechanistically, CREB dephosphorylation is rescued by the inhibition of PP2A, a phosphatase that targets CREB. Our results suggest that CLK2 is a regulatory component of diet-induced thermogenesis in BAT through increased CREB-dependent expression of UCP1. Copyright © 2017 Elsevier Inc. All rights reserved.

  11. Fast nanotopography imaging using a high speed cantilever with integrated heater-thermometer

    NASA Astrophysics Data System (ADS)

    Lee, Byeonghee; Somnath, Suhas; King, William P.

    2013-04-01

    This paper presents a high speed tapping cantilever with an integrated heater-thermometer for fast nanotopography imaging. The cantilever is much smaller and faster than previous heated cantilevers, with a length of 35 μm and a resonant frequency of 1.4 MHz. The mechanical response time is characterized by scanning over a backward-facing step of height 20 nm. The mechanical response time is 77 μs in air and 448 μs in water, which compares favorably to the fastest commercial cantilevers that do not have integrated heaters. The doped silicon cantilever is designed with an integrated heater that can heat and cool in about 10 μs and can operate in both air and water. We demonstrate standard laser-based topography imaging along with thermal topography imaging, when the cantilever is actuated via the piezoelectric shaker in an atomic force microscope system and when it is actuated by Lorentz forces. The cantilever can perform thermal topography imaging in tapping mode with an imaging resolution of 7 nm at a scan speed of 1.46 mm s-1.

  12. Fast and simple high-capacity quantum cryptography with error detection

    PubMed Central

    Lai, Hong; Luo, Ming-Xing; Pieprzyk, Josef; Zhang, Jun; Pan, Lei; Li, Shudong; Orgun, Mehmet A.

    2017-01-01

    Quantum cryptography is commonly used to generate fresh secure keys with quantum signal transmission for instant use between two parties. However, research shows that the relatively low key generation rate hinders its practical use where a symmetric cryptography component consumes the shared key. That is, the security of the symmetric cryptography demands frequent rate of key updates, which leads to a higher consumption of the internal one-time-pad communication bandwidth, since it requires the length of the key to be as long as that of the secret. In order to alleviate these issues, we develop a matrix algorithm for fast and simple high-capacity quantum cryptography. Our scheme can achieve secure private communication with fresh keys generated from Fibonacci- and Lucas- valued orbital angular momentum (OAM) states for the seed to construct recursive Fibonacci and Lucas matrices. Moreover, the proposed matrix algorithm for quantum cryptography can ultimately be simplified to matrix multiplication, which is implemented and optimized in modern computers. Most importantly, considerably information capacity can be improved effectively and efficiently by the recursive property of Fibonacci and Lucas matrices, thereby avoiding the restriction of physical conditions, such as the communication bandwidth. PMID:28406240

  13. Fast and simple high-capacity quantum cryptography with error detection.

    PubMed

    Lai, Hong; Luo, Ming-Xing; Pieprzyk, Josef; Zhang, Jun; Pan, Lei; Li, Shudong; Orgun, Mehmet A

    2017-04-13

    Quantum cryptography is commonly used to generate fresh secure keys with quantum signal transmission for instant use between two parties. However, research shows that the relatively low key generation rate hinders its practical use where a symmetric cryptography component consumes the shared key. That is, the security of the symmetric cryptography demands frequent rate of key updates, which leads to a higher consumption of the internal one-time-pad communication bandwidth, since it requires the length of the key to be as long as that of the secret. In order to alleviate these issues, we develop a matrix algorithm for fast and simple high-capacity quantum cryptography. Our scheme can achieve secure private communication with fresh keys generated from Fibonacci- and Lucas- valued orbital angular momentum (OAM) states for the seed to construct recursive Fibonacci and Lucas matrices. Moreover, the proposed matrix algorithm for quantum cryptography can ultimately be simplified to matrix multiplication, which is implemented and optimized in modern computers. Most importantly, considerably information capacity can be improved effectively and efficiently by the recursive property of Fibonacci and Lucas matrices, thereby avoiding the restriction of physical conditions, such as the communication bandwidth.

  14. Repeating Fast Radio Bursts from Highly Magnetized Pulsars Traveling through Asteroid Belts

    NASA Astrophysics Data System (ADS)

    Dai, Z. G.; Wang, J. S.; Wu, X. F.; Huang, Y. F.

    2016-09-01

    Very recently, Spitler et al. and Scholz et al. reported their detections of 16 additional bright bursts in the direction of the fast radio burst (FRB) 121102. This repeating FRB is inconsistent with all of the catastrophic event models put forward previously for hypothetically non-repeating FRBs. Here, we propose a different model, in which highly magnetized pulsars travel through the asteroid belts of other stars. We show that a repeating FRB could originate from such a pulsar encountering a large number of asteroids in the belt. During each pulsar-asteroid impact, an electric field induced outside of the asteroid has such a large component parallel to the stellar magnetic field that electrons are torn off the asteroidal surface and accelerated to ultra-relativistic energies instantaneously. The subsequent movement of these electrons along magnetic field lines will cause coherent curvature radiation, which can account for all of the properties of an FRB. In addition, this model can self-consistently explain the typical duration, luminosity, and repetitive rate of the 17 bursts of FRB 121102. The predicted occurrence rate of repeating FRB sources may imply that our model would be testable in the next few years.

  15. High time resolution electron measurement by Fast Electron energy Spectrum Analyzer (FESA)

    SciTech Connect

    Saito, Yoshifumi; Fujimoto, Masaki; Maezawa, Kiyoshi; Shinohara, Iku; Tsuda, Yuichi; Sasaki, Shintaro; Kojima, Hirotsugu

    2009-06-16

    We have newly developed an electron energy analyzer FESA (Fast Electron energy Spectrum Analyzer) for a future magnetospheric satellite mission SCOPE. The SCOPE mission is designed in order that observational studies from the cross-scale coupling viewpoint are enabled. One of the key observations necessary for the SCOPE mission is high-time resolution electron measurement. Eight FESAs on a spinning spacecraft are capable of measuring three dimensional electron distribution function with time resolution of 8 msec. FESA consists of two electrostatic analyzers that are composed of three nested hemispherical deflectors. Single FESA functions as four top-hat type electrostatic analyzers that can measure electrons with four different energies simultaneously. By measuring the characteristics of the test model FESA, we proved the validity of the design concept of FESA. Based on the measured characteristics, we designed FESA optimized for the SCOPE mission. This optimized analyzer has good enough performance to measure three dimensional electron distribution functions around the magnetic reconnection region in the Earth's magnetotail.

  16. Use of High-Power Combiners and Fast Directional Switches in ECRH Systems

    SciTech Connect

    Bruschi, A.; Bin, W.; D'Arcangelo, O.; Muzzini, V.; Kasparek, W.; Plaum, B.; Erckmann, V.; Petelin, M.; Lubyako, L.

    2009-11-26

    The new generation of compact devices for the combination and the fast switching of high-power millimeter-wave beams [1] for Electron Cyclotron Heating (ECH) gives the possibility to switch the power (in tens of microseconds) between two lines (or two ECH launchers, even modulating it between them) and combine two gyrotron sources (or in principle even more) in one single transmission line, for doubling the transmitted power. This is useful in many respects in order to: 1){approx}double the efficiency in modulated EC for neoclassical Tearing Modes (NTM) stabilization, 2) avoid to switch-off gyrotrons in conventional (slow) switching, 3) electronically control the power sharing between different applications (heating/current-drive or NTM stabilization), 4) upgrade the existing ECH systems to twice the power without adding complete transmission lines and launchers, 5) test components at a power doubled with respect to the power capability of the available sources. This opens the way to the development of a more effective 'active' real-time control of the ECRH power routing and generally to more flexible and powerful ECH systems. The development of different devices and the advantages for (and in view of) ITER are addressed.

  17. Z a Fast Pulsed Power Generator for Ultra-High Magnetic Field Generation

    NASA Astrophysics Data System (ADS)

    Spielman, R. B.; Stygar, W. A.; Struve, K. W.; Asay, J. R.; Hall, C. A.; Bernard, M. A.; Bailey, J. E.; McDaniel, D. H.

    2004-11-01

    Advances in fast, pulsed-power technologies have resulted in the development of very high current drivers that have current rise times ~100 ns. The largest such pulsed power driver today is the new Z accelerator located at Sandia National Laboratories in Albuquerque, New Mexico. Z can deliver more than 20 MA with a time-to-peak of 105 ns to low inductance (~1 nH) loads. Such large drivers are capable of directly generating magnetic fields approaching 3 kT in small, 1 cm3 volumes. In addition to direct field generation, Z can be used to compress an applied, axial seed field with a plasma. Flux compression schemes are not new and are, in fact, the basis of all explosive flux-compression generators, but we propose the use of plasma armatures rather than solid, conducting armatures. We present experimental results from the Z accelerator in which magnetic fields of ~2 kT are generated and measured with several diagnostics. Issues such as energy loss in solid conductors and dynamic response of current-carrying conductors to very large magnetic fields are reviewed in context with Z experiments. We describe planned flux-compression experiments that are expected to create the highest-magnitude uniform-field volumes yet attained in the laboratory.

  18. High-resolution imaging without iteration: a fast and robust method for breast ultrasound tomography.

    PubMed

    Huthwaite, P; Simonetti, F

    2011-09-01

    Breast ultrasound tomography has the potential to improve the cost, safety, and reliability of breast cancer screening and diagnosis over the gold-standard of mammography. Vital to achieving this potential is the development of imaging algorithms to unravel the complex anatomy of the breast and its mechanical properties. The solution most commonly relied upon is time-of-flight tomography, but this exhibits low resolution due to the presence of diffraction effects. Iterative full-wave inversion methods present one solution to achieve higher resolution, but these are slow and are not guaranteed to converge to the correct solution. Presented here is HARBUT, the hybrid algorithm for robust breast ultrasound tomography, which utilizes the complementary strengths of time-of-flight and diffraction tomography resulting in a direct, fast, robust and accurate high resolution method of reconstructing the sound speed through the breast. The algorithm is shown to produce accurate reconstructions with realistic data from a complex three-dimensional simulation, with masses as small as 4 mm being clearly visible. © 2011 Acoustical Society of America

  19. Fast asthenosphere motion in high-resolution global mantle flow models

    NASA Astrophysics Data System (ADS)

    Weismüller, Jens; Gmeiner, Björn; Bunge, Hans-Peter

    2016-04-01

    A variety of geologic observations point to fast upper mantle flow that may exceed plate tectonic velocities by an order of magnitude. At the same time there is mounting evidence from seismology for flow like structures in the upper 100-200 km of the mantle. Here we present a set of geodynamic simulations to link these observations. We model asthenospheric channels of varying thickness, in a range from a wide 1000 km channel to an extremely thin channel of 100 km, and viscosity contrasts between one and four orders of magnitude relative to the lower mantle. Using our new global high resolution mantle convection prototype Terra-Neo, we obtain an increase in velocity by a factor of ten between the thick and the very thin channel, translating into velocities of about 20 cm/a within the narrow asthenosphere. We further present and verify a simple Poiseuille flow model, which predicts that the upper mantle velocity scales with the inverse of the asthenosphere thickness.

  20. Fast and simple high-capacity quantum cryptography with error detection

    NASA Astrophysics Data System (ADS)

    Lai, Hong; Luo, Ming-Xing; Pieprzyk, Josef; Zhang, Jun; Pan, Lei; Li, Shudong; Orgun, Mehmet A.

    2017-04-01

    Quantum cryptography is commonly used to generate fresh secure keys with quantum signal transmission for instant use between two parties. However, research shows that the relatively low key generation rate hinders its practical use where a symmetric cryptography component consumes the shared key. That is, the security of the symmetric cryptography demands frequent rate of key updates, which leads to a higher consumption of the internal one-time-pad communication bandwidth, since it requires the length of the key to be as long as that of the secret. In order to alleviate these issues, we develop a matrix algorithm for fast and simple high-capacity quantum cryptography. Our scheme can achieve secure private communication with fresh keys generated from Fibonacci- and Lucas- valued orbital angular momentum (OAM) states for the seed to construct recursive Fibonacci and Lucas matrices. Moreover, the proposed matrix algorithm for quantum cryptography can ultimately be simplified to matrix multiplication, which is implemented and optimized in modern computers. Most importantly, considerably information capacity can be improved effectively and efficiently by the recursive property of Fibonacci and Lucas matrices, thereby avoiding the restriction of physical conditions, such as the communication bandwidth.

  1. Development of fast heating electron beam annealing setup for ultra high vacuum chamber

    SciTech Connect

    Das, Sadhan Chandra; Majumdar, Abhijit E-mail: majumdar@uni-greifswald.de; Hippler, R.; Katiyal, Sumant; Shripathi, T.

    2014-02-15

    We report the design and development of a simple, electrically low powered and fast heating versatile electron beam annealing setup (up to 1000 °C) working with ultra high vacuum (UHV) chamber for annealing thin films and multilayer structures. The important features of the system are constant temperature control in UHV conditions for the temperature range from room temperature to 1000 ºC with sufficient power of 330 W, at constant vacuum during annealing treatment. It takes approximately 6 min to reach 1000 °C from room temperature (∼10{sup −6} mbar) and 45 min to cool down without any extra cooling. The annealing setup consists of a UHV chamber, sample holder, heating arrangement mounted on suitable UHV electrical feed-through and electronic control and feedback systems to control the temperature within ±1 ºC of set value. The outside of the vacuum chamber is cooled by cold air of 20 °C of air conditioning machine used for the laboratory, so that chamber temperature does not go beyond 50 °C when target temperature is maximum. The probability of surface oxidation or surface contamination during annealing is examined by means of x-ray photoelectron spectroscopy of virgin Cu sample annealed at 1000 °C.

  2. Development of fast heating electron beam annealing setup for ultra high vacuum chamber

    NASA Astrophysics Data System (ADS)

    Das, Sadhan Chandra; Majumdar, Abhijit; Katiyal, Sumant; Shripathi, T.; Hippler, R.

    2014-02-01

    We report the design and development of a simple, electrically low powered and fast heating versatile electron beam annealing setup (up to 1000 °C) working with ultra high vacuum (UHV) chamber for annealing thin films and multilayer structures. The important features of the system are constant temperature control in UHV conditions for the temperature range from room temperature to 1000 °C with sufficient power of 330 W, at constant vacuum during annealing treatment. It takes approximately 6 min to reach 1000 °C from room temperature (˜10-6 mbar) and 45 min to cool down without any extra cooling. The annealing setup consists of a UHV chamber, sample holder, heating arrangement mounted on suitable UHV electrical feed-through and electronic control and feedback systems to control the temperature within ±1 °C of set value. The outside of the vacuum chamber is cooled by cold air of 20 °C of air conditioning machine used for the laboratory, so that chamber temperature does not go beyond 50 °C when target temperature is maximum. The probability of surface oxidation or surface contamination during annealing is examined by means of x-ray photoelectron spectroscopy of virgin Cu sample annealed at 1000 °C.

  3. Highly siderophile element systematics of abyssal peridotites from intermediate and fast spreading ridges

    NASA Astrophysics Data System (ADS)

    Brown, D. B.; Day, J. M.; Waters, C. L.

    2016-12-01

    Abyssal peridotites are residues of both modern and ancient partial melt extraction at oceanic ridges and can be used to examine melting processes and mantle heterogeneity. The highly siderophile elements (HSE: Os, Ir, Ru, Pt, Pd, Re, and the 187Re-187Os system embedded within them), are useful for investigating these issues, as they are generally strongly compatible. To date, limited data on HSE and Os isotopes has been obtained on abyssal peridotites from fast spreading centers. Here, we report new HSE abundance and 187Os/188Os data for Pacific Antarctic Ridge (PAR) and East Pacific Rise (EPR) abyssal peridotites. Samples from the PAR were dredged from two separate localities along the Udintsev Fracture Zone, and EPR samples were taken from Hess Deep. The PAR full spreading rate ranges from 54-83mm/year [1,2] and is 75 mm/year [2] at the Udintsev Fracture Zone. These spreading rates characterize the PAR as an intermediate spreading ridge, whereas the fast spreading EPR has a full rate ranging from 128-157 mm/year [3]. The 187Os/188Os ratios for whole-rocks from the PAR range from 0.114 to 0.134, with Re depletion ages (TRD) varying from 1 Ga to present. Despite the large variation in 187Os/188Os, HSE patterns are primitive mantle-like [4], with Ru/Ir ratios ranging from 1.5-2.1. Depletions in Re and Pd are present, as is expected in partial melt residues, and the samples have undergone 4-15% partial melting based on the rare earth elements (REE). The EPR exhibits higher levels of melt depletion ranging from 18-24%. New results show Hess Deep samples have 187Os/188Os ratios of 0.123 and 0.125 for whole-rocks. These findings indicate that PAR and EPR Os isotopic data overlap with the global record of abyssal peridotites from slower ridges and that Os isotopic heterogeneities are preserved across a wide range of spreading rates and degrees of melt extraction. [1] Géli, L., et al. (1997), Science, 278, 1281-1284; [2] Castillo, P.R., et al. (1998) EPSL, 154

  4. RADIOLOGICAL SAFETY ASSESSMENT FOR THE EXPERIMENTAL AREA OF A HYPER-INTENSE LASER WITH PEAK-POWER OF 1PW-CETAL.

    PubMed

    Florescu, M G; Duliu, O G; Pantazi, D; Ticos, C M; Sporea, D; Vasilache, R; Ionescu, V; Oane, M

    2016-09-24

    Ultra-high intensity lasers in use are connected with ionizing radiation sources that raise a real concern in relation to installations, personnel, population and environment protection. The shielding of target areas in these facilities has to be evaluated from the conceptual stage of the building design. The sizing of the protective concrete walls was determined using computer codes such as Fluka. For the experiments to be carried out in the facility of the Center for Advanced Laser Technologies (CETAL), both proton beams with the energy of 100 MeV and electron beams with 300 MeV energy were considered to calculate the dimensions of structural shielding and to establish technical solutions fulfilling the radiation protection constraints imposed by the National Commission for Nuclear Activities Control.

  5. High-throughput chemical residue analysis by fast extraction and dilution flow injection mass spectrometry.

    PubMed

    Nanita, Sergio C

    2011-01-21

    Fast extraction and dilution flow injection mass spectrometry (FED-FI-MS) is presented as a technique to increase throughput in quantitative multiresidue screening in complex matrices, while meeting current analytical method quality requirements.

  6. High-Voltage Power Supply With Fast Rise and Fall Times

    NASA Technical Reports Server (NTRS)

    Bearden, Douglas B.; Acker, Richard M.; Kapuslka, Robert E.

    2007-01-01

    A special-purpose high-voltage power supply can be electronically switched on and off with fast rise and fall times, respectively. The output potential is programmable from 20 to 1,250 V. An output current of 50 A can be sustained at 1,250 V. The power supply was designed specifically for electronically shuttering a microchannel plate in an x-ray detector that must operate with exposure times as short as 1 ms. The basic design of the power supply is also adaptable to other applications in which there are requirements for rapid slewing of high voltages. The power-supply circuitry (see figure) includes a preregulator, which is used to program the output at 1/30 of the desired output potential. After the desired voltage has been set, the outputs of a pulse width modulator (PWM) are enabled and used to amplify the preregulator output potential by 30. The amplification is achieved by use of two voltage doublers with a transformer that has two primary and two secondary windings. A resistor is used to limit the current by controlling the drive voltage of two field-effect transistors (FETs) during turn-on of the PWM. A pulse transformer is used to turn on four FETs to short-circuit four output capacitors when the outputs of the PWM have been disabled. The most notable aspects of the performance of the power supply are a rise time of only 80 s and a fall time of only 60 s at a load current of 50 A or less. Another notable aspect is that the application of a 0-to-5-V square wave to a shutdown pin of the PWM causes the production of a 0-to-1,250-V square wave at the output terminals.

  7. Edge Ion Heating by Launched High Harmonic Fast Waves in NSTX

    SciTech Connect

    T.M. Biewer; R.E. Bell; S.J. Diem; C.K. Phillips; J.R. Wilson; P.M. Ryan

    2004-12-01

    A new spectroscopic diagnostic on the National Spherical Torus Experiment (NSTX) measures the velocity distribution of ions in the plasma edge simultaneously along both poloidal and toroidal views. An anisotropic ion temperature is measured during high-power high harmonic fast wave (HHFW) radio-frequency (rf) heating in helium plasmas, with the poloidal ion temperature roughly twice the toroidal ion temperature. Moreover, the measured spectral distribution suggests that two populations of ions are present and have temperatures of typically 500 eV and 50 eV with rotation velocities of -50 km/s and -10 km/s, respectively (predominantly perpendicular to the local magnetic field). This bi-modal distribution is observed in both the toroidal and poloidal views (for both He{sup +} and C{sup 2+} ions), and is well correlated with the period of rf power application to the plasma. The temperature of the hot component is observed to increase with the applied rf power, which was scanned between 0 and 4.3 MW . The 30 MHz HHFW launched by the NSTX antenna is expected and observed to heat core electrons, but plasma ions do not resonate with the launched wave, which is typically at >10th harmonic of the ion cyclotron frequency in the region of observation. A likely ion heating mechanism is parametric decay of the launched HHFW into an Ion Bernstein Wave (IBW). The presence of the IBW in NSTX plasmas during HHFW application has been directly confirmed with probe measurements. IBW heating occurs in the perpendicular ion distribution, consistent with the toroidal and poloidal observations. Calculations of IBW propagation indicate that multiple waves could be created in the parametric decay process, and that most of the IBW power would be absorbed in the outer 10 to 20 cm of the plasma, predominantly on fully stripped ions. These predictions are in qualitative agreement with the observations, and must be accounted for when calculating the energy budget of the plasma.

  8. Electron emission in collisions of fast highly charged bare ions with helium atoms

    NASA Astrophysics Data System (ADS)

    Mondal, Abhoy; Mandal, Chittranjan; Purkait, Malay

    2016-01-01

    We have studied the electron emission from ground state helium atom in collision with fast bare heavy ions at intermediate and high incident energies. In the present study, we have applied the present three-body formalism of the three Coulomb wave (3C-3B) model and the previously adopted four-body formalism of the three Coulomb wave (3C-4B). To represent the active electron in the helium atom in the 3C-3B model, the initial bound state wavefunction is chosen to be hydrogenic with an effective nuclear charge. The wavefunction for the ejected electron in the exit channel has been approximated to be a Coulomb continuum wavefunction with same effective nuclear charge. Effectively the continuum-continuum correlation effect has been considered in the present investigation. Here we have calculated the energy and angular distribution of double differential cross sections (DDCS) at low and high energy electron emission from helium atom. The large forward-backward asymmetry is observed in the angular distribution which is explained in terms of the two-center effect (TCE). Our theoretical results are compared with available experimental results as well as other theoretical calculations based on the plain wave Born approximation (PWBA), continuum-distorted wave (CDW) approximation, continuum-distorted wave eikonal-initial state (CDW-EIS) approximation, and the corresponding values obtained from the 3C-4B model [S. Jana, R. Samanta, M. Purkait, Phys. Scr. 88, 055301 (2013)] respectively. It is observed that the four-body version of the present investigation produces results which are in better agreement with experimental observations for all cases.

  9. H.sub.2O doped WO.sub.3, ultra-fast, high-sensitivity hydrogen sensors

    DOEpatents

    Liu, Ping [Denver, CO; Tracy, C Edwin [Golden, CO; Pitts, J Roland [Lakewood, CO; Lee, Se-Hee [Lakewood, CO

    2011-03-22

    An ultra-fast response, high sensitivity structure for optical detection of low concentrations of hydrogen gas, comprising: a substrate; a water-doped WO.sub.3 layer coated on the substrate; and a palladium layer coated on the water-doped WO.sub.3 layer.

  10. High-performance rechargeable batteries with nanoparticle active materials, photochemically regenerable active materials, and fast solid-state ion conductors

    DOEpatents

    Farmer, Joseph C.

    2017-04-04

    A high-performance rechargeable battery using ultra-fast ion conductors. In one embodiment the rechargeable battery apparatus includes an enclosure, a first electrode operatively connected to the enclosure, a second electrode operatively connected to the enclosure, a nanomaterial in the enclosure, and a heat transfer unit.

  11. Fast-ion transport in qmin>2, high- β steady-state scenarios on DIII-D

    SciTech Connect

    Holcomb, C. T.; Heidbrink, W. W.; Ferron, J. R.; Van Zeeland, M. A.; Garofalo, A. M.; Solomon, W. M.; Gong, X.; Mueller, D.; Grierson, B.; Bass, E. M.; Collins, C.; Park, J. M.; Kim, K.; Luce, T. C.; Turco, F.; Pace, D. C.; Ren, Q.; Podesta, M.

    2015-05-22

    The results from experiments on DIII-D [J. L. Luxon, Fusion Sci. Technol. 48, 828 (2005)] aimed at developing high β steady-state operating scenarios with high-qminqmin confirm that fast-ion transport is a critical issue for advanced tokamak development using neutral beam injection current drive. In DIII-D, greater than 11 MW of neutral beam heating power is applied with the intent of maximizing βN and the noninductive current drive. However, in scenarios with qmin>2 that target the typical range of q95= 5–7 used in next-step steady-state reactor models, Alfvén eigenmodes cause greater fast-ion transport than classical models predict. This enhanced transport reduces the absorbed neutral beam heating power and current drive and limits the achievable βN. Conversely similar plasmas except with qmin just above 1 have approximately classical fast-ion transport. Experiments that take qmin>3 plasmas to higher βP with q95= 11–12 for testing long pulse operation exhibit regimes of better than expected thermal confinement. Compared to the standard high-qmin scenario, the high βP cases have shorter slowing-down time and lower ∇βfast, and this reduces the drive for Alfvénic modes, yielding nearly classical fast-ion transport, high values of normalized confinement, βN, and noninductive current fraction. These results suggest DIII-D might obtain better performance in lower-q95, high-qmin plasmas using broader neutral beam heating profiles and increased direct electron heating power to lower the drive for Alfvén eigenmodes.

  12. Fast-ion transport in qmin>2, high- β steady-state scenarios on DIII-D

    DOE PAGES

    Holcomb, C. T.; Heidbrink, W. W.; Ferron, J. R.; ...

    2015-05-22

    The results from experiments on DIII-D [J. L. Luxon, Fusion Sci. Technol. 48, 828 (2005)] aimed at developing high β steady-state operating scenarios with high-qminqmin confirm that fast-ion transport is a critical issue for advanced tokamak development using neutral beam injection current drive. In DIII-D, greater than 11 MW of neutral beam heating power is applied with the intent of maximizing βN and the noninductive current drive. However, in scenarios with qmin>2 that target the typical range of q95= 5–7 used in next-step steady-state reactor models, Alfvén eigenmodes cause greater fast-ion transport than classical models predict. This enhanced transport reducesmore » the absorbed neutral beam heating power and current drive and limits the achievable βN. Conversely similar plasmas except with qmin just above 1 have approximately classical fast-ion transport. Experiments that take qmin>3 plasmas to higher βP with q95= 11–12 for testing long pulse operation exhibit regimes of better than expected thermal confinement. Compared to the standard high-qmin scenario, the high βP cases have shorter slowing-down time and lower ∇βfast, and this reduces the drive for Alfvénic modes, yielding nearly classical fast-ion transport, high values of normalized confinement, βN, and noninductive current fraction. These results suggest DIII-D might obtain better performance in lower-q95, high-qmin plasmas using broader neutral beam heating profiles and increased direct electron heating power to lower the drive for Alfvén eigenmodes.« less

  13. Fast-ion transport in qmin>2, high- β steady-state scenarios on DIII-D

    DOE PAGES

    Holcomb, C. T.; Heidbrink, W. W.; Ferron, J. R.; ...

    2015-05-22

    The results from experiments on DIII-D [J. L. Luxon, Fusion Sci. Technol. 48, 828 (2005)] aimed at developing high β steady-state operating scenarios with high-qminqmin confirm that fast-ion transport is a critical issue for advanced tokamak development using neutral beam injection current drive. In DIII-D, greater than 11 MW of neutral beam heating power is applied with the intent of maximizing βN and the noninductive current drive. However, in scenarios with qmin>2 that target the typical range of q95= 5–7 used in next-step steady-state reactor models, Alfvén eigenmodes cause greater fast-ion transport than classical models predict. This enhanced transport reducesmore » the absorbed neutral beam heating power and current drive and limits the achievable βN. Conversely similar plasmas except with qmin just above 1 have approximately classical fast-ion transport. Experiments that take qmin>3 plasmas to higher βP with q95= 11–12 for testing long pulse operation exhibit regimes of better than expected thermal confinement. Compared to the standard high-qmin scenario, the high βP cases have shorter slowing-down time and lower ∇βfast, and this reduces the drive for Alfvénic modes, yielding nearly classical fast-ion transport, high values of normalized confinement, βN, and noninductive current fraction. These results suggest DIII-D might obtain better performance in lower-q95, high-qmin plasmas using broader neutral beam heating profiles and increased direct electron heating power to lower the drive for Alfvén eigenmodes.« less

  14. Fast-ion transport in qmin>2, high- β steady-state scenarios on DIII-D

    SciTech Connect

    Holcomb, C. T.; Heidbrink, W. W.; Ferron, J. R.; Van Zeeland, M. A.; Garofalo, A. M.; Solomon, W. M.; Gong, X.; Mueller, D.; Grierson, B.; Bass, E. M.; Collins, C.; Park, J. M.; Kim, K.; Luce, T. C.; Turco, F.; Pace, D. C.; Ren, Q.; Podesta, M.

    2015-05-22

    The results from experiments on DIII-D [J. L. Luxon, Fusion Sci. Technol. 48, 828 (2005)] aimed at developing high β steady-state operating scenarios with high-qminqmin confirm that fast-ion transport is a critical issue for advanced tokamak development using neutral beam injection current drive. In DIII-D, greater than 11 MW of neutral beam heating power is applied with the intent of maximizing βN and the noninductive current drive. However, in scenarios with qmin>2 that target the typical range of q95= 5–7 used in next-step steady-state reactor models, Alfvén eigenmodes cause greater fast-ion transport than classical models predict. This enhanced transport reduces the absorbed neutral beam heating power and current drive and limits the achievable βN. Conversely similar plasmas except with qmin just above 1 have approximately classical fast-ion transport. Experiments that take qmin>3 plasmas to higher βP with q95= 11–12 for testing long pulse operation exhibit regimes of better than expected thermal confinement. Compared to the standard high-qmin scenario, the high βP cases have shorter slowing-down time and lower ∇βfast, and this reduces the drive for Alfvénic modes, yielding nearly classical fast-ion transport, high values of normalized confinement, βN, and noninductive current fraction. These results suggest DIII-D might obtain better performance in lower-q95, high-qmin plasmas using broader neutral beam heating profiles and increased direct electron heating power to lower the drive for Alfvén eigenmodes.

  15. High-harmonic fast-wave power flow along magnetic field lines in the scrape-off layer of NSTX.

    PubMed

    Perkins, R J; Hosea, J C; Kramer, G J; Ahn, J-W; Bell, R E; Diallo, A; Gerhardt, S; Gray, T K; Green, D L; Jaeger, E F; Jaworski, M A; LeBlanc, B P; McLean, A; Maingi, R; Phillips, C K; Roquemore, L; Ryan, P M; Sabbagh, S; Taylor, G; Wilson, J R

    2012-07-27

    A significant fraction of high-harmonic fast-wave (HHFW) power applied to NSTX can be lost to the scrape-off layer (SOL) and deposited in bright and hot spirals on the divertor rather than in the core plasma. We show that the HHFW power flows to these spirals along magnetic field lines passing through the SOL in front of the antenna, implying that the HHFW power couples across the entire width of the SOL rather than mostly at the antenna face. This result will help guide future efforts to understand and minimize these edge losses in order to maximize fast-wave heating and current drive.

  16. Cyclic pulse coding for hybrid fast BOTDA/Raman sensor

    NASA Astrophysics Data System (ADS)

    Muanenda, Yonas; Taki, Mohammad; Toccafondo, Iacopo; Signorini, Alessandro; Nannipieri, Tiziano; Oton, Claudio J.; Di Pasquale, Fabrizio

    2014-05-01

    We propose and experimentally demonstrate a fully hybrid distributed sensing scheme that uses a single narrow-band laser to perform fast measurement of the BFS using BOTDA and simultaneous temperature measurement based on spontaneous Raman scattering over 10 km of single mode fiber. The use of cyclic pulse coding effectively reduces the pump peak power levels required for accurate Raman-based distributed temperature measurement, enhancing at the same time the speed of the BFS measurement in the BOTDA technique.

  17. Tunable, high-power, continuous-wave dual-polarization Yb-fiber oscillator.

    PubMed

    Zeil, Peter; Pasiskevicius, Valdas; Laurell, Fredrik

    2015-06-29

    We demonstrate a high-power, dual-polarization Yb-fiber oscillator, by separately locking the two linear polarization states defined by slow and fast axis of a polarization-maintaining gain fiber with volume Bragg gratings. Dual-line lasing is achieved with a tunable wavelength separation from 0.03 to 2 THz, while exceeding output powers of 78 W over the entire tuning range, maintaining a high beam-quality with M(2)<1.2. With this laser configuration we achieve a peak-to-peak power variation of <1% for the dual-line signal and <3% for the individual signals.

  18. Fast charging technique for high power LiFePO4 batteries: A mechanistic analysis of aging

    NASA Astrophysics Data System (ADS)

    Anseán, D.; Dubarry, M.; Devie, A.; Liaw, B. Y.; García, V. M.; Viera, J. C.; González, M.

    2016-07-01

    One of the major issues hampering the acceptance of electric vehicles (EVs) is the anxiety associated with long charging time. Hence, the ability to fast charging lithium-ion battery (LIB) systems is gaining notable interest. However, fast charging is not tolerated by all LIB chemistries because it affects battery functionality and accelerates its aging processes. Here, we investigate the long-term effects of multistage fast charging on a commercial high power LiFePO4-based cell and compare it to another cell tested under standard charging. Coupling incremental capacity (IC) and IC peak area analysis together with mechanistic model simulations ('Alawa' toolbox with harvested half-cell data), we quantify the degradation modes that cause aging of the tested cells. The results show that the proposed fast charging technique caused similar aging effects as standard charging. The degradation is caused by a linear loss of lithium inventory, coupled with a less degree of linear loss of active material on the negative electrode. This study validates fast charging as a feasible mean of operation for this particular LIB chemistry and cell architecture. It also illustrates the benefits of a mechanistic approach to understand cell degradation on commercial cells.

  19. Automatic building detection based on Purposive FastICA (PFICA) algorithm using monocular high resolution Google Earth images

    NASA Astrophysics Data System (ADS)

    Ghaffarian, Saman; Ghaffarian, Salar

    2014-11-01

    This paper proposes an improved FastICA model named as Purposive FastICA (PFICA) with initializing by a simple color space transformation and a novel masking approach to automatically detect buildings from high resolution Google Earth imagery. ICA and FastICA algorithms are defined as Blind Source Separation (BSS) techniques for unmixing source signals using the reference data sets. In order to overcome the limitations of the ICA and FastICA algorithms and make them purposeful, we developed a novel method involving three main steps: 1-Improving the FastICA algorithm using Moore-Penrose pseudo inverse matrix model, 2-Automated seeding of the PFICA algorithm based on LUV color space and proposed simple rules to split image into three regions; shadow + vegetation, baresoil + roads and buildings, respectively, 3-Masking out the final building detection results from PFICA outputs utilizing the K-means clustering algorithm with two number of clusters and conducting simple morphological operations to remove noises. Evaluation of the results illustrates that buildings detected from dense and suburban districts with divers characteristics and color combinations using our proposed method have 88.6% and 85.5% overall pixel-based and object-based precision performances, respectively.

  20. Sampling frequency, response times and embedded signal filtration in fast, high efficiency liquid chromatography: A tutorial.

    PubMed

    Wahab, M Farooq; Dasgupta, Purnendu K; Kadjo, Akinde F; Armstrong, Daniel W

    2016-02-11

    With increasingly efficient columns, eluite peaks are increasingly narrower. To take full advantage of this, choice of the detector response time and the data acquisition rate a.k.a. detector sampling frequency, have become increasingly important. In this work, we revisit the concept of data sampling from the theorem variously attributed to Whittaker, Nyquist, Kotelnikov, and Shannon. Focusing on time scales relevant to the current practice of high performance liquid chromatography (HPLC) and optical absorbance detection (the most commonly used method), even for very narrow simulated peaks Fourier transformation shows that theoretical minimum sampling frequency is still relatively low (<10 Hz). However, this consideration alone may not be adequate for real chromatograms when an appreciable amount of noise is present. Further, depending on the instrument, the manufacturer's choice of a particular data bunching/integration/response time condition may be integrally coupled to the sampling frequency. In any case, the exact nature of signal filtration often occurs in a manner neither transparent to nor controllable by the user. Using fast chromatography on a state-of-the-art column (38,000 plates), we evaluate the responses produced by different present generation instruments, each with their unique black box digital filters. We show that the common wisdom of sampling 20 points per peak can be inadequate for high efficiency columns and that the sampling frequency and response choices do affect the peak shape. If the sampling frequency is too low or response time is too large, the observed peak shapes will not remain as narrow as they really are - this is especially true for high efficiency and high speed separations. It is shown that both sampling frequency and digital filtering affect the retention time, noise amplitude, peak shape and width in a complex fashion. We show how a square-wave driven light emitting diode source can reveal the nature of the embedded filter