Science.gov

Sample records for acoustic output power

  1. A Novel Device for Total Acoustic Output Measurement of High Power Transducers

    NASA Astrophysics Data System (ADS)

    Howard, S.; Twomey, R.; Morris, H.; Zanelli, C. I.

    2010-03-01

    The objective of this work was to develop a device for ultrasound power measurement applicable over a broad range of medical transducer types, orientations and powers, and which supports automatic measurements to simplify use and minimize errors. Considering all the recommendations from standards such as IEC 61161, an accurate electromagnetic null-balance has been designed for ultrasound power measurements. The sensing element is placed in the water to eliminate errors due to surface tension and water evaporation, and the motion and detection of force is constrained to one axis, to increase immunity to vibration from the floor, water sloshing and water surface waves. A transparent tank was designed so it could easily be submerged in a larger tank to accommodate large transducers or side-firing geometries, and can also be turned upside-down for upward-firing transducers. A vacuum lid allows degassing the water and target in situ. An external control module was designed to operate the sensing/driving loop and to communicate to a local computer for data logging. The sensing algorithm, which incorporates temperature compensation, compares the feedback force needed to cancel the motion for sources in the "on" and "off" states. These two states can be controlled by the control unit or manually by the user, under guidance by a graphical user interface (the system presents measured power live during collection). Software allows calibration to standard weights, or to independently calibrated acoustic sources. The design accommodates a variety of targets, including cone, rubber, brush targets and an oil-filled target for power measurement via buoyancy changes. Measurement examples are presented, including HIFU sources operating at powers from 1 to 100.

  2. On the output of acoustical sources

    NASA Technical Reports Server (NTRS)

    Levine, H.

    1979-01-01

    Contents: (1) a theoretical basis for local power calculation; (2) source radiation in the presence of a half-plane; (3) radiation from a line source near an edge at which a Kutta condition holds; (4) radiation by a point source above a plane independence boundary; and (5) power output of a point source in a uniform flow.

  3. Standardized multiple output power supply

    NASA Technical Reports Server (NTRS)

    Ragusa, E. V.

    1975-01-01

    A comprehensive program to develop a prototype model of a standardized multiple output power supply for use in space flight applications is described. The prototype unit was tested and evaluated to assure that the design would provide near optimum performance for the planned application. The prototype design used a dc-to-dc converter incorporating reqenerative current feedback with a time-ratio controlled duty cycle to achieve high efficiency over a wide variation of input voltage and output loads. The packaging concept uses a mainframe capable of accommodating up to four inverter/regulator modules with one common input filter and housekeeping module. Each inverter/regulator module provides a maximum of 100 watts or 10 amperes. Each module is adaptable to operate at any voltage between 4.0 volts and 108 volts. The prototype unit contains +5, + or - 15 and +28 volt modules.

  4. Dual output acoustic wave sensor for molecular identification

    DOEpatents

    Frye, Gregory C.; Martin, Stephen J.

    1991-01-01

    A method of identification and quantification of absorbed chemical species by measuring changes in both the velocity and the attenuation of an acoustic wave traveling through a thin film into which the chemical species is sorbed. The dual output response provides two independent sensor responses from a single sensing device thereby providing twice as much information as a single output sensor. This dual output technique and analysis allows a single sensor to provide both the concentration and the identity of a chemical species or permits the number of sensors required for mixtures to be reduced by a factor of two.

  5. Exercise efficiency of low power output cycling.

    PubMed

    Reger, M; Peterman, J E; Kram, R; Byrnes, W C

    2013-12-01

    Exercise efficiency at low power outputs, energetically comparable to daily living activities, can be influenced by homeostatic perturbations (e.g., weight gain/loss). However, an appropriate efficiency calculation for low power outputs used in these studies has not been determined. Fifteen active subjects (seven females, eight males) performed 14, 5-min cycling trials: two types of seated rest (cranks vertical and horizontal), passive (motor-driven) cycling, no-chain cycling, no-load cycling, cycling at low (10, 20, 30, 40 W), and moderate (50, 60, 80, 100, 120 W) power outputs. Mean delta efficiency was 57% for low power outputs compared to 41.3% for moderate power outputs. Means for gross (3.6%) and net (5.7%) efficiencies were low at the lowest power output. At low power outputs, delta and work efficiency values exceeded theoretical values. In conclusion, at low power outputs, none of the common exercise efficiency calculations gave values comparable to theoretical muscle efficiency. However, gross efficiency and the slope and intercept of the metabolic power vs mechanical power output regression provide insights that are still valuable when studying homeostatic perturbations.

  6. Power output measurement during treadmill cycling.

    PubMed

    Coleman, D A; Wiles, J D; Davison, R C R; Smith, M F; Swaine, I L

    2007-06-01

    The study aim was to consider the use of a motorised treadmill as a cycling ergometry system by assessing predicted and recorded power output values during treadmill cycling. Fourteen male cyclists completed repeated cycling trials on a motorised treadmill whilst riding their own bicycle fitted with a mobile ergometer. The speed, gradient and loading via an external pulley system were recorded during 20-s constant speed trials and used to estimate power output with an assumption about the contribution of rolling resistance. These values were then compared with mobile ergometer measurements. To assess the reliability of measured power output values, four repeated trials were conducted on each cyclist. During level cycling, the recorded power output was 257.2 +/- 99.3 W compared to the predicted power output of 258.2 +/- 99.9 W (p > 0.05). For graded cycling, there was no significant difference between measured and predicted power output, 268.8 +/- 109.8 W vs. 270.1 +/- 111.7 W, p > 0.05, SEE 1.2 %. The coefficient of variation for mobile ergometer power output measurements during repeated trials ranged from 1.5 % (95 % CI 1.2 - 2.0 %) to 1.8 % (95 % CI 1.5 - 2.4 %). These results indicate that treadmill cycling can be used as an ergometry system to assess power output in cyclists with acceptable accuracy.

  7. Powered-Lift Aerodynamics and Acoustics. [conferences

    NASA Technical Reports Server (NTRS)

    1976-01-01

    Powered lift technology is reviewed. Topics covered include: (1) high lift aerodynamics; (2) high speed and cruise aerodynamics; (3) acoustics; (4) propulsion aerodynamics and acoustics; (5) aerodynamic and acoustic loads; and (6) full-scale and flight research.

  8. Coupling output of multichannel high power microwaves

    SciTech Connect

    Li Guolin; Shu Ting; Yuan Chengwei; Zhang Jun; Yang Jianhua; Jin Zhenxing; Yin Yi; Wu Dapeng; Zhu Jun; Ren Heming; Yang Jie

    2010-12-15

    The coupling output of multichannel high power microwaves is a promising technique for the development of high power microwave technologies, as it can enhance the output capacities of presently studied devices. According to the investigations on the spatial filtering method and waveguide filtering method, the hybrid filtering method is proposed for the coupling output of multichannel high power microwaves. As an example, a specific structure is designed for the coupling output of S/X/X band three-channel high power microwaves and investigated with the hybrid filtering method. In the experiments, a pulse of 4 GW X band beat waves and a pulse of 1.8 GW S band microwave are obtained.

  9. Coupling output of multichannel high power microwaves

    NASA Astrophysics Data System (ADS)

    Li, Guolin; Shu, Ting; Yuan, Chengwei; Zhang, Jun; Yang, Jianhua; Jin, Zhenxing; Yin, Yi; Wu, Dapeng; Zhu, Jun; Ren, Heming; Yang, Jie

    2010-12-01

    The coupling output of multichannel high power microwaves is a promising technique for the development of high power microwave technologies, as it can enhance the output capacities of presently studied devices. According to the investigations on the spatial filtering method and waveguide filtering method, the hybrid filtering method is proposed for the coupling output of multichannel high power microwaves. As an example, a specific structure is designed for the coupling output of S/X/X band three-channel high power microwaves and investigated with the hybrid filtering method. In the experiments, a pulse of 4 GW X band beat waves and a pulse of 1.8 GW S band microwave are obtained.

  10. Output beam analysis of high power COIL

    NASA Astrophysics Data System (ADS)

    Yu, Deli; Sang, Fengting; Jin, Yuqi; Sun, Yizhu

    2003-03-01

    As the output power of a chemical oxygen iodine laser (COIL) increases, the output laser beam instability appears as the far-field beam spot drift and deformation for the large Fresnel number unstable resonator. In order to interpret this phenomenon, an output beam mode simulation code was developed with the fast Fourier transform method. The calculation results show that the presence of the nonuniform gain in COIL produces a skewed output intensity distribution, which causes the mirror tilt and bulge due to the thermal expansion. With the output power of COIL increases, the mirror surfaces, especially the back surface of the scraper mirror, absorb more and more heat, which causes the drift and deformation of far field beam spot seriously. The initial misalignment direction is an important factor for the far field beam spot drifting and deformation.

  11. Realistic power output modeling of CPV modules

    NASA Astrophysics Data System (ADS)

    Steiner, Marc; Siefer, Gerald; Bösch, Armin; Hornung, Thorsten; Bett, Andreas W.

    2012-10-01

    In this work, we introduce a new model called YieldOpt, which calculates the power output of CPV modules. It uses SMARTS2 to model the spectral irradiance, a ray tracing program to model the optics and SPICE network simulation to model the electrical characteristic of triple-junction (3J) cells. The calculated power output is compared to data measured of five CPV modules operating in Freiburg, Germany during a period from October 2011 to March 2012. Four of the modules use lattice-matched 3J cells; one of these modules has also reflective secondary optics. In one of the five modules novel metamorphic 3J cells are used. The agreement of the predicted power output calculated by YieldOpt with the measured data is quantified using the normalized root mean square error. A good agreement between simulation and measurement is achieved. Moreover, the predicted energy yield derived from the new model is compared with the measured energy yield. A good agreement between the measured data and simulated data is achieved. In addition, a high accuracy in predicting the energy yield of different CPV modules is demonstrated. Finally, the new model is compared with three empirical models.

  12. Uncertainties in predicting solar panel power output

    NASA Technical Reports Server (NTRS)

    Anspaugh, B.

    1974-01-01

    The problem of calculating solar panel power output at launch and during a space mission is considered. The major sources of uncertainty and error in predicting the post launch electrical performance of the panel are considered. A general discussion of error analysis is given. Examples of uncertainty calculations are included. A general method of calculating the effect on the panel of various degrading environments is presented, with references supplied for specific methods. A technique for sizing a solar panel for a required mission power profile is developed.

  13. On source radiation. [power output computation

    NASA Technical Reports Server (NTRS)

    Levine, H.

    1980-01-01

    The power output from given sources is usually ascertained via an energy flux integral over the normal directions to a remote (farfield) surface; an alternative procedure, which utilizes an integral that specifies the direct rate of working by the source on the resultant field, is described and illustrated for both point and continuous source distributions. A comparison between the respective procedures is made in the analysis of sound radiated from a periodic dipole source whose axis rotates in a plane, on a full or partial angular range, with prescribed frequency. Thus, adopting a conventional approach, Sretenskii (1956) characterizes the rotating dipole in terms of an infinite number of stationary ones along a pair of orthogonal directions in the plane and, through the farfield representation of the latter, arrives at a series development for the instantaneous radiated power, whereas the local manner of power calculation dispenses with the equivalent infinite aggregate of sources and yields a compact analytical result.

  14. Output of acoustical sources. [effects of structural elements and background flow on immobile multipolar point radiation

    NASA Technical Reports Server (NTRS)

    Levine, H.

    1980-01-01

    Acoustic radiation from a source, here viewed as an immobile point singularity with periodic strength and a given multipolar nature, is affected by the presence of nearly structural elements (e.g., rigid or impedance surfaces) as well as that of a background flow in the medium. An alternative to the conventional manner of calculating the net source output by integrating the energy flux over a distant control surface is described; this involves a direct evaluation of the secondary wavefunction at the position of the primary source and obviates the need for a (prospectively difficult) flux integration. Various full and half-planar surface configurations with an adjacent source are analyzed in detail, and the explicit results obtained, in particular, for the power factor of a dipole brings out a substantial rise in its output as the source nears the sharp edge of a half-plane.

  15. Windmill having thermal and electric power output

    SciTech Connect

    Kenney, C.E.

    1980-11-25

    A windmill is described which has thermal and electric power output and includes windmill blades rotatably mounted and connected to a speed increaser mechanism of gears and shafts and a centrifugal compressor connected to the windmill thru the speed increaser to be driven by virtue of the wind applied to the blades of the windmill itself. A directional control is connected to the windmill head to have the windmill blades face into the wind, as desired. The compressor is connected to an insulated heat storage tank which contains storage material, such as brick, and the compressor discharge velocity and pressure difference are converted to heat, and the compressor fluid is returned to the compressor thru a screen which protects the compressor, and there is a flow control which automatically compensates for changes in density of the circulated air or compressor fluid. Also, a gas turbine generator can be connected with the compressor to be driven thereby, and electric elements could be connected with the generator for producing electricity. Two other embodiments show an impeller type of air brake and a valve and a heat-sensitive control, for generating heat or power.

  16. Caffeine supplementation and peak anaerobic power output.

    PubMed

    Glaister, Mark; Muniz-Pumares, Daniel; Patterson, Stephen D; Foley, Paul; McInnes, Gillian

    2015-01-01

    The aim of this study was to investigate the effects of caffeine supplementation on peak anaerobic power output (Wmax). Using a counterbalanced, randomised, double-blind, placebo-controlled design, 14 well-trained men completed three trials of a protocol consisting of a series of 6-s cycle ergometer sprints, separated by 5-min passive recovery periods. Sprints were performed at progressively increasing torque factors to determine the peak power/torque relationship and Wmax. Apart from Trial 1 (familiarisation), participants ingested a capsule containing 5 mg·kg(-1) of caffeine or placebo, one hour before each trial. The effects of caffeine on blood lactate were investigated using capillary samples taken after each sprint. The torque factor which produced Wmax was not significantly different (p ≥ 0.05) between the caffeine (1.15 ± 0.08 N·m·kg(-1)) and placebo (1.13 ± 0.10 N·m·kg(-1)) trials. There was, however, a significant effect (p < 0.05) of supplementation on Wmax, with caffeine producing a higher value (1885 ± 303 W) than placebo (1835 ± 290 W). Analysis of the blood lactate data revealed a significant (p < 0.05) torque factor × supplement interaction with values being significantly higher from the sixth sprint (torque factor 1.0 N·m·kg(-1)) onwards following caffeine supplementation. The results of this study confirm previous reports that caffeine supplementation significantly increases blood lactate and Wmax. These findings may explain why the majority of previous studies, which have used fixed-torque factors of around 0.75 N·m·kg(-1) and thereby failing to elicit Wmax, have failed to find an effect of caffeine on sprinting performance.

  17. Design and characterization of a high-power ultrasound driver with ultralow-output impedance.

    PubMed

    Lewis, George K; Olbricht, William L

    2009-11-01

    We describe a pocket-sized ultrasound driver with an ultralow-output impedance amplifier circuit (less than 0.05 ohms) that can transfer more than 99% of the voltage from a power supply to the ultrasound transducer with minimal reflections. The device produces high-power acoustical energy waves while operating at lower voltages than conventional ultrasound driving systems because energy losses owing to mismatched impedance are minimized. The peak performance of the driver is measured experimentally with a PZT-4, 1.54 MHz, piezoelectric ceramic, and modeled using an adjusted Mason model over a range of transducer resonant frequencies. The ultrasound driver can deliver a 100 V(pp) (peak to peak) square-wave signal across 0-8 MHz ultrasound transducers in 5 ms bursts through continuous wave operation, producing acoustic powers exceeding 130 W. Effects of frequency, output impedance of the driver, and input impedance of the transducer on the maximum acoustic output power of piezoelectric transducers are examined. The small size, high power, and efficiency of the ultrasound driver make this technology useful for research, medical, and industrial ultrasonic applications.

  18. Most efficient quantum thermoelectric at finite power output.

    PubMed

    Whitney, Robert S

    2014-04-01

    Machines are only Carnot efficient if they are reversible, but then their power output is vanishingly small. Here we ask, what is the maximum efficiency of an irreversible device with finite power output? We use a nonlinear scattering theory to answer this question for thermoelectric quantum systems, heat engines or refrigerators consisting of nanostructures or molecules that exhibit a Peltier effect. We find that quantum mechanics places an upper bound on both power output and on the efficiency at any finite power. The upper bound on efficiency equals Carnot efficiency at zero power output but decays with increasing power output. It is intrinsically quantum (wavelength dependent), unlike Carnot efficiency. This maximum efficiency occurs when the system lets through all particles in a certain energy window, but none at other energies. A physical implementation of this is discussed, as is the suppression of efficiency by a phonon heat flow.

  19. Compact waveguide power divider with multiple isolated outputs

    DOEpatents

    Moeller, Charles P.

    1987-01-01

    A waveguide power divider (10) for splitting electromagnetic microwave power and directionally coupling the divided power includes an input waveguide (21) and reduced height output waveguides (23) interconnected by axial slots (22) and matched loads (25) and (26) positioned at the unused ends of input and output guides (21) and (23) respectively. The axial slots are of a length such that the wave in the input waveguide (21) is directionally coupled to the output waveguides (23). The widths of input guide (21) and output guides (23) are equal and the width of axial slots (22) is one half of the width of the input guide (21).

  20. Measurement of ultrasonic power using an acoustically absorbing well.

    PubMed

    Sutton, Yvonne; Shaw, Adam; Zeqiri, Bajram

    2003-10-01

    This paper describes a quick and cost-effective method for constructing a radiation force balance for measuring ultrasonic output power. It utilises a target manufactured from a high-quality acoustical absorber material. The target geometry is in the form of a cup or well that is water-filled and placed directly on the pan of a top-loading chemical balance, thus overcoming the need for the traditional gantry arrangement found in the majority of commercially available balances. The face of the transducer is placed directly in the water contained within the well. This simplification reduces time spent in setting up a balance for measurement, and targets can be manufactured to any required geometry and used on any suitable top-loading balance to measure output power. Within this study, the performance of the absorbing well method was evaluated over the frequency range of 1 MHz to 5 MHz, for acoustic power levels up to 1 W. Power measurements on three transducers were compared with measurements made on the National Physical Laboratory (NPL) primary standard radiation force balance and good agreement is demonstrated between the two systems. At a power of 50 mW, using a chemical balance of resolution 0.1 mg, typical type A (random) uncertainties were +/- 2.0% when expressed at the 95% confidence level.

  1. The effect of aerodynamic parameters on power output of windmills

    NASA Technical Reports Server (NTRS)

    Wiesner, W.

    1973-01-01

    Aerodynamic results for a study on windpower generation are reported. Windmill power output is presented in terms that are commonly used in rotary wing analysis, namely, power output as a function of drag developed by the windmill. Effect of tip speed ratio, solidity, twist, wind angle, blade setting and airfoil characteristics are given.

  2. Maximizing power output from continuous-wave single-frequency fiber amplifiers.

    PubMed

    Ward, Benjamin G

    2015-02-15

    This Letter reports on a method of maximizing the power output from highly saturated cladding-pumped continuous-wave single-frequency fiber amplifiers simultaneously, taking into account the stimulated Brillouin scattering and transverse modal instability thresholds. This results in a design figure of merit depending on the fundamental mode overlap with the doping profile, the peak Brillouin gain coefficient, and the peak mode coupling gain coefficient. This figure of merit is then numerically analyzed for three candidate fiber designs including standard, segmented acoustically tailored, and micro-segmented acoustically tailored photonic-crystal fibers. It is found that each of the latter two fibers should enable a 50% higher output power than standard photonic crystal fiber.

  3. Power output during women's World Cup road cycle racing.

    PubMed

    Ebert, Tammie R; Martin, David T; McDonald, Warren; Victor, James; Plummer, John; Withers, Robert T

    2005-12-01

    Little information exists on the power output demands of competitive women's road cycle racing. The purpose of our investigation was to document the power output generated by elite female road cyclists who achieved success in FLAT and HILLY World Cup races. Power output data were collected from 27 top-20 World Cup finishes (19 FLAT and 8 HILLY) achieved by 15 nationally ranked cyclists (mean +/- SD; age: 24.1+/-4.0 years; body mass: 57.9+/-3.6 kg; height: 168.7+/-5.6 cm; VO2max 63.6+/-2.4 mL kg(-1) min(-1); peak power during graded exercise test (GXT(peak power)): 310+/-25 W). The GXT determined GXT(peak power), VO2peak lactate threshold (LT) and anaerobic threshold (AT). Bicycles were fitted with SRM powermeters, which recorded power (W), cadence (rpm), distance (km) and speed (km h(-1)). Racing data were analysed to establish time in power output and metabolic threshold bands and maximal mean power (MMP) over different durations. When compared to HILLY, FLAT were raced at a similar cadence (75+/-8 vs. 75+/-4 rpm, P=0.93) but higher speed (37.6+/-2.6 vs. 33.9+/-2.7 km h(-1), P=0.008) and power output (192+/-21 vs. 169+/-17 W, P=0.04; 3.3+/-0.3 vs. 3.0+/-0.4 W kg(-1), P=0.04). During FLAT races, riders spent significantly more time above 500 W, while greater race time was spent between 100 and 300 W (LT-AT) for HILLY races, with higher MMPs for 180-300 s. Racing terrain influenced the power output profiles of our internationally competitive female road cyclists. These data are the first to define the unique power output requirements associated with placing well in both flat and hilly women's World Cup cycling events.

  4. Complementary power output characteristics of electromagnetic generators and triboelectric generators

    NASA Astrophysics Data System (ADS)

    Fan, Feng-Ru; Tang, Wei; Yao, Yan; Luo, Jianjun; Zhang, Chi; Wang, Zhong Lin

    2014-04-01

    Recently, a triboelectric generator (TEG) has been invented to convert mechanical energy into electricity by a conjunction of triboelectrification and electrostatic induction. Compared to the traditional electromagnetic generator (EMG) that produces a high output current but low voltage, the TEG has different output characteristics of low output current but high output voltage. In this paper, we present a comparative study regarding the fundamentals of TEGs and EMGs. The power output performances of the EMG and the TEG have a special complementary relationship, with the EMG being a voltage source and the TEG a current source. Utilizing a power transformed and managed (PTM) system, the current output of a TEG can reach as high as ˜3 mA, which can be coupled with the output signal of an EMG to enhance the output power. We also demonstrate a design to integrate a TEG and an EMG into a single device for simultaneously harvesting mechanical energy. In addition, the integrated NGs can independently output a high voltage and a high current to meet special needs.

  5. Complementary power output characteristics of electromagnetic generators and triboelectric generators.

    PubMed

    Fan, Feng-Ru; Tang, Wei; Yao, Yan; Luo, Jianjun; Zhang, Chi; Wang, Zhong Lin

    2014-04-01

    Recently, a triboelectric generator (TEG) has been invented to convert mechanical energy into electricity by a conjunction of triboelectrification and electrostatic induction. Compared to the traditional electromagnetic generator (EMG) that produces a high output current but low voltage, the TEG has different output characteristics of low output current but high output voltage. In this paper, we present a comparative study regarding the fundamentals of TEGs and EMGs. The power output performances of the EMG and the TEG have a special complementary relationship, with the EMG being a voltage source and the TEG a current source. Utilizing a power transformed and managed (PTM) system, the current output of a TEG can reach as high as ∼3 mA, which can be coupled with the output signal of an EMG to enhance the output power. We also demonstrate a design to integrate a TEG and an EMG into a single device for simultaneously harvesting mechanical energy. In addition, the integrated NGs can independently output a high voltage and a high current to meet special needs.

  6. Impact of Altitude on Power Output during Cycling Stage Racing

    PubMed Central

    Garvican-Lewis, Laura A; Clark, Bradley; Martin, David T.; Schumacher, Yorck Olaf; McDonald, Warren; Stephens, Brian; Ma, Fuhai; Thompson, Kevin G.; Gore, Christopher J.; Menaspà, Paolo

    2015-01-01

    Purpose The purpose of this study was to quantify the effects of moderate-high altitude on power output, cadence, speed and heart rate during a multi-day cycling tour. Methods Power output, heart rate, speed and cadence were collected from elite male road cyclists during maximal efforts of 5, 15, 30, 60, 240 and 600 s. The efforts were completed in a laboratory power-profile assessment, and spontaneously during a cycling race simulation near sea-level and an international cycling race at moderate-high altitude. Matched data from the laboratory power-profile and the highest maximal mean power output (MMP) and corresponding speed and heart rate recorded during the cycling race simulation and cycling race at moderate-high altitude were compared using paired t-tests. Additionally, all MMP and corresponding speeds and heart rates were binned per 1000m (<1000m, 1000–2000, 2000–3000 and >3000m) according to the average altitude of each ride. Mixed linear modelling was used to compare cycling performance data from each altitude bin. Results Power output was similar between the laboratory power-profile and the race simulation, however MMPs for 5–600 s and 15, 60, 240 and 600 s were lower (p ≤ 0.005) during the race at altitude compared with the laboratory power-profile and race simulation, respectively. Furthermore, peak power output and all MMPs were lower (≥ 11.7%, p ≤ 0.001) while racing >3000 m compared with rides completed near sea-level. However, speed associated with MMP 60 and 240 s was greater (p < 0.001) during racing at moderate-high altitude compared with the race simulation near sea-level. Conclusion A reduction in oxygen availability as altitude increases leads to attenuation of cycling power output during competition. Decrement in cycling power output at altitude does not seem to affect speed which tended to be greater at higher altitudes. PMID:26629912

  7. Electrochemistry in Organisms: Electron Flow and Power Output

    ERIC Educational Resources Information Center

    Chirpich, Thomas P.

    1975-01-01

    Presents a series of calculations, appropriate for the freshman level, to determine the flow of electrons to oxygen along the electron transport chain. States that living organisms resemble fuel cells and develops calculations for determining power output. (GS)

  8. Acoustic monitoring of power-plant valves

    NASA Astrophysics Data System (ADS)

    Allen, J. W.; Hartman, W. F.; Robinson, J. C.

    1982-06-01

    Advanced surveillance diagnostics were applied to key nuclear power plant valves to improve the availability of the power plant. Two types of valves were monitored: BWR three-stage, pilot-operated safety/relief valves and PWR feedwater control valves. Excessive leakage across the pilot-disc seat in BWR safety/relief valves can cause the second-stage pressure to reach the critical value that activates the valve, even though the set pressure was not exceeded. Acoustic emissions created by the leak noise were monitored and calibrated to indicate incipient activation of the safety/relief valve. Hydrodynamic, vibration, control and process signals from PWR feedwater control valves were monitored by a mini-computer based surveillance system. On-line analysis of these signals coupled with earlier analytic modelling identified: (1) cavitation, (2) changes in steam packaging tightness, (3) valve stem torquing, (4) transducer oscillations, and (5) peak vibration levels during power transients.

  9. Hybrid Seminumerical Simulation Scheme to Predict Transducer Outputs of Acoustic Microscopes.

    PubMed

    Nierla, Michael; Rupitsch, Stefan J

    2016-02-01

    We present a seminumerical simulation method called SIRFEM, which enables the efficient prediction of high-frequency transducer outputs. In particular, this is important for acoustic microscopy where the specimen under investigation is immersed in a coupling fluid. Conventional finite-element (FE) simulations for such applications would consume too much computational power due to the required spatial and temporal discretization, especially for the coupling fluid between ultrasonic transducer and specimen. However, FE simulations are in most cases essential to consider the mode conversion at and inside the solid specimen as well as the wave propagation in its interior. SIRFEM reduces the computational effort of pure FE simulations by treating only the solid specimen and a small part of the fluid layer with FE. The propagation in the coupling fluid from transducer to specimen and back is processed by the so-called spatial impulse response (SIR). Through this hybrid approach, the number of elements as well as the number of time steps for the FE simulation can be reduced significantly, as it is presented for an axis-symmetric setup. Three B-mode images of a plane 2-D setup-computed at a transducer center frequency of 20 MHz-show that SIRFEM is, furthermore, able to predict reflections at inner structures as well as multiple reflections between those structures and the specimen's surface. For the purpose of a pure 2-D setup, the SIR of a curved-line transducer is derived and compared to the response function of a cylindrically focused aperture of negligible extend in the third spatial dimension.

  10. Maximal power output by solar cells with angular confinement.

    PubMed

    Höhn, Oliver; Kraus, Tobias; Bauhuis, Gerard; Schwarz, Ulrich T; Bläsi, Benedikt

    2014-05-01

    Angularly selective filters can increase the efficiency of radiatively limited solar cells. A restriction of the acceptance angle is linked to the kind of utilizable solar spectrum (global or direct radiation). This has to be considered when calculating the potential enhancement of both the efficiency and the power output. In this paper, different concepts to realize angularly selective filters are compared regarding their limits for efficiency and power output per unit area. First experimental results of a promising system based on a thin-film filter as the angularly selective element are given to demonstrate the practical relevance of such systems.

  11. High-output-power polarization-insensitive SOA

    NASA Astrophysics Data System (ADS)

    Morito, Ken

    2002-05-01

    An 1550 nm semiconductor optical amplifier (SOA) with a very thin tensile-strained bulk active layer and active width-tapered spot-size converters was developed. The SOA module exhibited a record high saturation output power of +17 dBm together with a low noise figure of 7 dB, large gain of 19 dB and small polarization sensitivity of 0.2 dB. A good eye pattern without waveform distortion due to the pattern effect was obtained for amplified 10 Gb/s NRZ signals up to an average output power of +12 dBm.

  12. Multi-input multi-output underwater communications over sparse and frequency modulated acoustic channels.

    PubMed

    Ling, Jun; Zhao, Kexin; Li, Jian; Nordenvaad, Magnus Lundberg

    2011-07-01

    This paper addresses multi-input multi-output (MIMO) communications over sparse acoustic channels suffering from frequency modulations. An extension of the recently introduced SLIM algorithm, which stands for sparse learning via iterative minimization, is presented to estimate the sparse and frequency modulated acoustic channels. The extended algorithm is referred to as generalization of SLIM (GoSLIM). The sparseness is exploited through a hierarchical Bayesian model, and because GoSLIM is user parameter free, it is easy to use in practical applications. Moreover this paper considers channel equalization and symbol detection for various MIMO transmission schemes, including both space-time block coding and spatial multiplexing, under the challenging channel conditions. The effectiveness of the proposed approaches is demonstrated using in-water experimental measurements recently acquired during WHOI09 and ACOMM10 experiments.

  13. Muscle power output limits fast-start performance in fish.

    PubMed

    Wakeling, J M; Johnston, I A

    1998-05-01

    Fast-starts associated with escape responses were filmed at the median habitat temperatures of six teleost fish: Notothenia coriiceps and Notothenia rossii (Antarctica), Myoxocephalus scorpius (North Sea), Scorpaena notata and Serranus cabrilla (Mediterranean) and Paracirrhites forsteri (Indo-West-Pacific Ocean). Methods are presented for estimating the spine positions for silhouettes of swimming fish. These methods were used to validate techniques for calculating kinematics and muscle dynamics during fast-starts. The starts from all species show common patterns, with waves of body curvature travelling from head to tail and increasing in amplitude. Cross-validation with sonomicrometry studies allowed gearing ratios between the red and white muscle to be calculated. Gearing ratios must decrease towards the tail with a corresponding change in muscle geometry, resulting in similar white muscle fibre strains in all the myotomes during the start. A work-loop technique was used to measure mean muscle power output at similar strain and shortening durations to those found in vivo. The fast Sc. notata myotomal fibres produced a mean muscle-mass-specific power of 142.7 W kg-1 at 20 degrees C. Velocity, acceleration and hydrodynamic power output increased both with the travelling rate of the wave of body curvature and with the habitat temperature. At all temperatures, the predicted mean muscle-mass-specific power outputs, as calculated from swimming sequences, were similar to the muscle power outputs measured from work-loop experiments.

  14. Selectively manipulable acoustic-powered microswimmers

    PubMed Central

    Ahmed, Daniel; Lu, Mengqian; Nourhani, Amir; Lammert, Paul E.; Stratton, Zak; Muddana, Hari S.; Crespi, Vincent H.; Huang, Tony Jun

    2015-01-01

    Selective actuation of a single microswimmer from within a diverse group would be a first step toward collaborative guided action by a group of swimmers. Here we describe a new class of microswimmer that accomplishes this goal. Our swimmer design overcomes the commonly-held design paradigm that microswimmers must use non-reciprocal motion to achieve propulsion; instead, the swimmer is propelled by oscillatory motion of an air bubble trapped within the swimmer's polymer body. This oscillatory motion is driven by the application of a low-power acoustic field, which is biocompatible with biological samples and with the ambient liquid. This acoustically-powered microswimmer accomplishes controllable and rapid translational and rotational motion, even in highly viscous liquids (with viscosity 6,000 times higher than that of water). And by using a group of swimmers each with a unique bubble size (and resulting unique resonance frequencies), selective actuation of a single swimmer from among the group can be readily achieved. PMID:25993314

  15. Low power acoustic harvesting of aerosols

    SciTech Connect

    Kaduchak, G.; Sinha, D. N.

    2001-01-01

    A new acoustic device for levitation and/or concentration of aerosols and sniall liquid/solid samples (up to several millimeters in diameter) in air has been developed. The device is inexpensive, low-power, and, in its simplest embodiment, does not require accurate alignmen1 of a resonant cavity. It is constructed from a cylindrical PZT tube of outside diameter D = 19.0 mm and thickness-to-radius ratio h/a - 0.03. The lowest-order breathing mode of the tube is tuned to match a resonant mode of the interior air-filled cylindrical cavity. A high Q cavity results that can be driven efficiently. An acoustic standing wave is created in the inteirior cavity of the cylindrical shell where particle concrmtration takes place at the nodal planes of the field. It is shown that drops of water in excess of 1 mm in diameter may be levitated against the force of gravity for approxirnately 100 mW of input electrical power. The main objective of the research is to implement this lowpower device to concentrate and harvest aerosols in a flowing system. Several different cavity geonietries iwe presented for efficient collection of 1 he conaartratetl aerosols. Concentraiion factors greater than 40 iue demonstrated for particles of size 0.7 1.1 in a flow volume of 50 L/minute.

  16. Acoustic monitoring of power plant valves

    NASA Astrophysics Data System (ADS)

    Allen, J. W.; Hartman, W. F.; Robinson, J. C.

    1982-06-01

    Advanced surveillance diagnostics were applied to key nuclear power plant valves to improve the availability of the power plant. Two types of valves were monitored: boiling water reactor (BWR) three-stage, pilot-operated safety/relief valves and pressurized water reactor (PWR) feedwater control valves. Excessive leakage across the pilot-disc seat in BWR safety/relief valves can cause the second-stage pressure to reach the critical value that activates the valve, even though the set pressure was not exceeded. Acoustic emission created by the leak noise were monitored and calibrated to indicate incipient activation of the safety/relief valve. Hydrodynamic, vibration, control and process signals frm PWR feedwater control valves were monitored by a mini-computer based surveillance system.

  17. Acoustic power measurement of high-intensity focused ultrasound transducer using a pressure sensor.

    PubMed

    Zhou, Yufeng

    2015-03-01

    The acoustic power of high-intensity focused ultrasound (HIFU) is an important parameter that should be measured prior to each treatment to guarantee effective and safe outcomes. A new calibration technique was developed that involves estimating the pressure distribution, calculating the acoustic power using an underwater pressure blast sensor, and compensating the contribution of harmonics to the acoustic power. The output of a clinical extracorporeal HIFU system (center frequency of ~1 MHz, p+ = 2.5-57.2 MPa, p(-) = -1.8 to -13.9 MPa, I(SPPA) = 513-22,940 W/cm(2), -6 dB size of 1.6 × 10 mm: lateral × axial) was measured using this approach and then compared with that obtained using a radiation force balance. Similarities were found between each method at acoustic power ranging from 18.2 W to 912 W with an electrical-to-acoustic conversion efficiency of ~42%. The proposed method has advantages of low weight, smaller size, high sensitivity, quick response, high signal-to-noise ratio (especially at low power output), robust performance, and easy operation of HIFU exposimetry measurement.

  18. Acoustic power measurement of high-intensity focused ultrasound transducer using a pressure sensor.

    PubMed

    Zhou, Yufeng

    2015-03-01

    The acoustic power of high-intensity focused ultrasound (HIFU) is an important parameter that should be measured prior to each treatment to guarantee effective and safe outcomes. A new calibration technique was developed that involves estimating the pressure distribution, calculating the acoustic power using an underwater pressure blast sensor, and compensating the contribution of harmonics to the acoustic power. The output of a clinical extracorporeal HIFU system (center frequency of ~1 MHz, p+ = 2.5-57.2 MPa, p(-) = -1.8 to -13.9 MPa, I(SPPA) = 513-22,940 W/cm(2), -6 dB size of 1.6 × 10 mm: lateral × axial) was measured using this approach and then compared with that obtained using a radiation force balance. Similarities were found between each method at acoustic power ranging from 18.2 W to 912 W with an electrical-to-acoustic conversion efficiency of ~42%. The proposed method has advantages of low weight, smaller size, high sensitivity, quick response, high signal-to-noise ratio (especially at low power output), robust performance, and easy operation of HIFU exposimetry measurement. PMID:25659300

  19. MOPA configuration light source with 5 W output power

    NASA Astrophysics Data System (ADS)

    Kaczmarek, Pawel; Soboń, Grzegorz; WÄ Ż, Adam; Dudzik, Grzegorz; Antończak, Arkadiusz; Abramski, Krzysztof

    2013-01-01

    In this paper we present a device - fiber based coherent light source operating at 1550 nm wavelength and 5 W of the output power. It is made completely of the fiber elements without any bulk optics therefore it is stable and resistant to the environmental conditions. The main idea was to use so called MOPA (Master Oscillator Power Amplifier) configuration to obtain universal design. Thus the device can be easily configured to work in couple different operation regimes.

  20. Voltage Control in Distribution Systems Considered Reactive Power Output Sharing

    NASA Astrophysics Data System (ADS)

    Oshiro, Masato; Senjyu, Tomonobu; Yona, Atsushi; Urasaki, Naomitsu; Funabashi, Toshihisa

    In recent years, distributed generation (DG) and renewable energy source (RES) are attracting special attention to distribution systems. Renewable energy such as photovoltaic (PV) system and wind turbine generator are used as a source of clean energy. However, the large amount of distributed generation causes voltage deviation beyond a statutory range in distribution systems. This paper proposes a methodology for voltage control by using inverters interfaced with DG and tap changing transformers. In the proposed method a one-day schedule of voltage references for the control devices are determined by an optimization technique based on predicted values of load demand and PV power generation. Furthermore, decided reactive power output according to the locally measurable voltage based on droop characteristic. Slope and base value on droop characteristic are selected by fuzzy control. The proposed method accomplishes improvement against voltage distribution considered the reactive power output sharing and reduction of distribution loss. The effectiveness of the proposed method is verified by using MATLAB®.

  1. Mechanical power output during running accelerations in wild turkeys.

    PubMed

    Roberts, Thomas J; Scales, Jeffrey A

    2002-05-01

    We tested the hypothesis that the hindlimb muscles of wild turkeys (Meleagris gallopavo) can produce maximal power during running accelerations. The mechanical power developed during single running steps was calculated from force-plate and high-speed video measurements as turkeys accelerated over a trackway. Steady-speed running steps and accelerations were compared to determine how turkeys alter their running mechanics from a low-power to a high-power gait. During maximal accelerations, turkeys eliminated two features of running mechanics that are characteristic of steady-speed running: (i) they produced purely propulsive horizontal ground reaction forces, with no braking forces, and (ii) they produced purely positive work during stance, with no decrease in the mechanical energy of the body during the step. The braking and propulsive forces ordinarily developed during steady-speed running are important for balance because they align the ground reaction force vector with the center of mass. Increases in acceleration in turkeys correlated with decreases in the angle of limb protraction at toe-down and increases in the angle of limb retraction at toe-off. These kinematic changes allow turkeys to maintain the alignment of the center of mass and ground reaction force vector during accelerations when large propulsive forces result in a forward-directed ground reaction force. During the highest accelerations, turkeys produced exclusively positive mechanical power. The measured power output during acceleration divided by the total hindlimb muscle mass yielded estimates of peak instantaneous power output in excess of 400 W kg(-1) hindlimb muscle mass. This value exceeds estimates of peak instantaneous power output of turkey muscle fibers. The mean power developed during the entire stance phase increased from approximately zero during steady-speed runs to more than 150 W kg(-1) muscle during the highest accelerations. The high power outputs observed during accelerations

  2. Femtosecond fiber CPA system emitting 830 W average output power.

    PubMed

    Eidam, Tino; Hanf, Stefan; Seise, Enrico; Andersen, Thomas V; Gabler, Thomas; Wirth, Christian; Schreiber, Thomas; Limpert, Jens; Tünnermann, Andreas

    2010-01-15

    In this Letter we report on the generation of 830 W compressed average power from a femtosecond fiber chirped pulse amplification (CPA) system. In the high-power operation we achieved a compressor throughput of about 90% by using high-efficiency dielectric gratings. The output pulse duration of 640 fs at 78 MHz repetition rate results in a peak power of 12 MW. Additionally, we discuss further a scaling potential toward and beyond the kilowatt level by overcoming the current scaling limitations imposed by the transversal spatial hole burning.

  3. Power output of field-based downhill mountain biking.

    PubMed

    Hurst, Howard Thomas; Atkins, Stephen

    2006-10-01

    The purpose of this study was to assess the power output of field-based downhill mountain biking. Seventeen trained male downhill cyclists (age 27.1 +/- 5.1 years) competing nationally performed two timed runs of a measured downhill course. An SRM powermeter was used to simultaneously record power, cadence, and speed. Values were sampled at 1-s intervals. Heart rates were recorded at 5-s intervals using a Polar S710 heart rate monitor. Peak and mean power output were 834 +/- 129 W and 75 +/- 26 W respectively. Mean power accounted for only 9% of peak values. Paradoxically, mean heart rate was 168 +/- 9 beats x min(-1) (89% of age-predicted maximum heart rate). Mean cadence (27 +/- 5 rev x min(-1)) was significantly related to speed (r = 0.51; P < 0.01). Analysis revealed an average of 38 pedal actions per run, with average pedalling periods of 5 s. Power and cadence were not significantly related to run time or any other variable. Our results support the intermittent nature of downhill mountain biking. The poor relationships between power and run time and between cadence and run time suggest they are not essential pre-requisites to downhill mountain biking performance and indicate the importance of riding dynamics to overall performance. PMID:17115519

  4. Theory and investigation of acoustic multiple-input multiple-output systems based on spherical arrays in a room.

    PubMed

    Morgenstern, Hai; Rafaely, Boaz; Zotter, Franz

    2015-11-01

    Spatial attributes of room acoustics have been widely studied using microphone and loudspeaker arrays. However, systems that combine both arrays, referred to as multiple-input multiple-output (MIMO) systems, have only been studied to a limited degree in this context. These systems can potentially provide a powerful tool for room acoustics analysis due to the ability to simultaneously control both arrays. This paper offers a theoretical framework for the spatial analysis of enclosed sound fields using a MIMO system comprising spherical loudspeaker and microphone arrays. A system transfer function is formulated in matrix form for free-field conditions, and its properties are studied using tools from linear algebra. The system is shown to have unit-rank, regardless of the array types, and its singular vectors are related to the directions of arrival and radiation at the microphone and loudspeaker arrays, respectively. The formulation is then generalized to apply to rooms, using an image source method. In this case, the rank of the system is related to the number of significant reflections. The paper ends with simulation studies, which support the developed theory, and with an extensive reflection analysis of a room impulse response, using the platform of a MIMO system.

  5. Theory and investigation of acoustic multiple-input multiple-output systems based on spherical arrays in a room.

    PubMed

    Morgenstern, Hai; Rafaely, Boaz; Zotter, Franz

    2015-11-01

    Spatial attributes of room acoustics have been widely studied using microphone and loudspeaker arrays. However, systems that combine both arrays, referred to as multiple-input multiple-output (MIMO) systems, have only been studied to a limited degree in this context. These systems can potentially provide a powerful tool for room acoustics analysis due to the ability to simultaneously control both arrays. This paper offers a theoretical framework for the spatial analysis of enclosed sound fields using a MIMO system comprising spherical loudspeaker and microphone arrays. A system transfer function is formulated in matrix form for free-field conditions, and its properties are studied using tools from linear algebra. The system is shown to have unit-rank, regardless of the array types, and its singular vectors are related to the directions of arrival and radiation at the microphone and loudspeaker arrays, respectively. The formulation is then generalized to apply to rooms, using an image source method. In this case, the rank of the system is related to the number of significant reflections. The paper ends with simulation studies, which support the developed theory, and with an extensive reflection analysis of a room impulse response, using the platform of a MIMO system. PMID:26627773

  6. Compact electret energy harvester with high power output

    NASA Astrophysics Data System (ADS)

    Pondrom, P.; Sessler, G. M.; Bös, J.; Melz, T.

    2016-08-01

    Compact electret energy harvesters, based on a design recently introduced, are presented. Using electret surface potentials in the 400 V regime and a seismic mass of 10 g, it was possible to generate output power up to 0.6 mW at 36 Hz for an input acceleration of 1 g. Following the presentation of an analytical model allowing for the calculation of the power generated in a load resistance at the resonance frequency of the harvesters, experimental results are shown and compared to theoretical predictions. Finally, the performance of the electret harvesters is assessed using a figure of merit.

  7. Multi-decadal Variability of the Wind Power Output

    NASA Astrophysics Data System (ADS)

    Kirchner Bossi, Nicolas; García-Herrera, Ricardo; Prieto, Luis; Trigo, Ricardo M.

    2014-05-01

    The knowledge of the long-term wind power variability is essential to provide a realistic outlook on the power output during the lifetime of a planned wind power project. In this work, the Power Output (Po) of a market wind turbine is simulated with a daily resolution for the period 1871-2009 at two different locations in Spain, one at the Central Iberian Plateau and another at the Gibraltar Strait Area. This is attained through a statistical downscaling of the daily wind conditions. It implements a Greedy Algorithm as classificator of a geostrophic-based wind predictor, which is derived by considering the SLP daily field from the 56 ensemble members of the longest homogeneous reanalysis available (20CR, 1871-2009). For calibration and validation purposes we use 10 years of wind observations (the predictand) at both sites. As a result, a series of 139 annual wind speed Probability Density Functions (PDF) are obtained, with a good performance in terms of wind speed uncertainty reduction (average daily wind speed MAE=1.48 m/s). The obtained centennial series allow to investigate the multi-decadal variability of wind power from different points of view. Significant periodicities around the 25-yr frequency band, as well as long-term linear trends are detected at both locations. In addition, a negative correlation is found between annual Po at both locations, evidencing the differences in the dynamical mechanisms ruling them (and possible complementary behavior). Furthermore, the impact that the three leading large-scale circulation patterns over Iberia (NAO, EA and SCAND) exert over wind power output is evaluated. Results show distinct (and non-stationary) couplings to these forcings depending on the geographical position and season or month. Moreover, significant non-stationary correlations are observed with the slow varying Atlantic Multidecadal Oscillation (AMO) index for both case studies. Finally, an empirical relationship is explored between the annual Po and the

  8. Using machine learning to predict wind turbine power output

    NASA Astrophysics Data System (ADS)

    Clifton, A.; Kilcher, L.; Lundquist, J. K.; Fleming, P.

    2013-06-01

    Wind turbine power output is known to be a strong function of wind speed, but is also affected by turbulence and shear. In this work, new aerostructural simulations of a generic 1.5 MW turbine are used to rank atmospheric influences on power output. Most significant is the hub height wind speed, followed by hub height turbulence intensity and then wind speed shear across the rotor disk. These simulation data are used to train regression trees that predict the turbine response for any combination of wind speed, turbulence intensity, and wind shear that might be expected at a turbine site. For a randomly selected atmospheric condition, the accuracy of the regression tree power predictions is three times higher than that from the traditional power curve methodology. The regression tree method can also be applied to turbine test data and used to predict turbine performance at a new site. No new data are required in comparison to the data that are usually collected for a wind resource assessment. Implementing the method requires turbine manufacturers to create a turbine regression tree model from test site data. Such an approach could significantly reduce bias in power predictions that arise because of the different turbulence and shear at the new site, compared to the test site.

  9. Listening to music affects diurnal variation in muscle power output.

    PubMed

    Chtourou, H; Chaouachi, A; Hammouda, O; Chamari, K; Souissi, N

    2012-01-01

    The purpose of this investigation was to assess the effects of listening to music while warming-up on the diurnal variations of power output during the Wingate test. 12 physical education students underwent four Wingate tests at 07:00 and 17:00 h, after 10 min of warm-up with and without listening to music. The warm-up consisted of 10 min of pedalling at a constant pace of 60 rpm against a light load of 1 kg. During the Wingate test, peak and mean power were measured. The main finding was that peak and mean power improved from morning to afternoon after no music warm-up (p<0.001 and p<0.01, respectively). These diurnal variations disappeared for mean power and persisted with an attenuated morning-evening difference (p<0.05) for peak power after music warm-up. Moreover, peak and mean power were significantly higher after music than no music warm-up during the two times of testing. Thus, as it is a legal method and an additional aid, music should be used during warm-up before performing activities requiring powerful lower limbs' muscles contractions, especially in the morning competitive events.

  10. Distribution of Acoustic Power Spectra for an Isolated Helicopter Fuselage

    NASA Astrophysics Data System (ADS)

    Kusyumov, A. N.; Mikhailov, S. A.; Garipova, L. I.; Batrakov, A. S.; Barakos, G.

    2016-03-01

    The broadband aerodynamic noise can be studied, assuming isotropic flow, turbulence and decay. Proudman's approach allows practical calculations of noise based on CFD solutions of RANS or URANS equations at the stage of post processing and analysis of the solution. Another aspect is the broadband acoustic spectrum and the distribution of acoustic power over a range of frequencies. The acoustic energy spectrum distribution in isotropic turbulence is non monotonic and has a maximum at a certain value of Strouhal number. In the present work the value of acoustic power peak frequency is determined using a prescribed form of acoustic energy spectrum distribution presented in papers by S. Sarkar and M. Y. Hussaini and by G. M. Lilley. CFD modelling of the flow around isolated helicopter fuselage model was considered using the HMB CFD code and the RANS equations.

  11. A model to predict the power output from wind farms

    SciTech Connect

    Landberg, L.

    1997-12-31

    This paper will describe a model that can predict the power output from wind farms. To give examples of input the model is applied to a wind farm in Texas. The predictions are generated from forecasts from the NGM model of NCEP. These predictions are made valid at individual sites (wind farms) by applying a matrix calculated by the sub-models of WASP (Wind Atlas Application and Analysis Program). The actual wind farm production is calculated using the Riso PARK model. Because of the preliminary nature of the results, they will not be given. However, similar results from Europe will be given.

  12. Derivation of continuous wave mode output power from burst mode measurements in high-intensity ultrasound applications.

    PubMed

    Haller, Julian; Wilkens, Volker

    2014-03-01

    Measurement of the acoustic output power of transducers in burst mode and derivation of the results to the continuous wave (CW) case reduces heating problems during power measurements with radiation force balances and absorbing targets at high power levels, but requires the knowledge of an "effective duty factor," DReff. In this work, an alternative method for determining DReff is presented that allows the determination at any input voltage amplitude as it can be calculated from the input voltage rf signal in burst mode. Thus with this method, it is not necessary to apply CW signals at all.

  13. Acoustic output measured by thermal and mechanical indices during fetal echocardiography at the time of the first trimester scan.

    PubMed

    Nemescu, Dragos; Berescu, Anca

    2015-01-01

    We measured acoustic output, expressed as the thermal index (TI) and mechanical index (MI), during fetal echocardiography at the time of the first trimester scan. TI and MI were retrieved from the saved displays during gray-mode, high-definition color flow Doppler and pulsed-wave Doppler (tricuspid flow) ultrasound examinations of the fetal heart and from the ductus venosus assessment. A total of 399 fetal cardiac examinations were evaluated. There was a significant increase in TI values from B-mode studies (0.07 ± 0.04 [mean ± SD]) to color flow mapping (0.2 ± 0.0) and pulsed-wave Doppler studies (0.36 ± 0.05). The TI from ductus venosus assessment (0.1 ± 0.01) was significantly lower than those from Doppler examinations of the heart. MI values from B-mode scans (0.65 ± 0.12) and color flow mapping (0.71 ± 0.11) were comparable, although different, and both values were higher than those from pulsed-wave Doppler tricuspid evaluation (0.39 ± 0.03). There were no differences in MI values from power Doppler assessment between the tricuspid flow and ductus venosus. Safety indices were remarkably stable and were largely constant, especially for color Doppler (TI), tricuspid flow (MI) and ductus venosus assessment (TI, MI). We acquired satisfactory Doppler images and/or signals at acoustic levels that were lower than the actual recommendations and never reached a TI of 0.5.

  14. Acoustical power amplification and damping by temperature gradients.

    PubMed

    Biwa, Tetsushi; Komatsu, Ryo; Yazaki, Taichi

    2011-01-01

    Ceperley proposed a concept of a traveling wave heat engine ["A pistonless Stirling engine-The traveling wave heat engine," J. Acoust. Soc. Am. 66, 1508-1513 (1979).] that provided a starting point of thermoacoustics today. This paper verifies experimentally his idea through observation of amplification and strong damping of a plane acoustic traveling wave as it passes through axial temperature gradients. The acoustic power gain is shown to obey a universal curve specified by a dimensionless parameter ωτα; ω is the angular frequency and τα is the relaxation time for the gas to thermally equilibrate with channel walls. As an application of his idea, a three-stage acoustic power amplifier is developed, which attains the gain up to 10 with a moderate temperature ratio of 2.3. PMID:21302995

  15. Acoustical power amplification and damping by temperature gradients.

    PubMed

    Biwa, Tetsushi; Komatsu, Ryo; Yazaki, Taichi

    2011-01-01

    Ceperley proposed a concept of a traveling wave heat engine ["A pistonless Stirling engine-The traveling wave heat engine," J. Acoust. Soc. Am. 66, 1508-1513 (1979).] that provided a starting point of thermoacoustics today. This paper verifies experimentally his idea through observation of amplification and strong damping of a plane acoustic traveling wave as it passes through axial temperature gradients. The acoustic power gain is shown to obey a universal curve specified by a dimensionless parameter ωτα; ω is the angular frequency and τα is the relaxation time for the gas to thermally equilibrate with channel walls. As an application of his idea, a three-stage acoustic power amplifier is developed, which attains the gain up to 10 with a moderate temperature ratio of 2.3.

  16. Spin-on-doping for output power improvement of silicon nanowire array based thermoelectric power generators

    SciTech Connect

    Xu, B. Fobelets, K.

    2014-06-07

    The output power of a silicon nanowire array (NWA)-bulk thermoelectric power generator (TEG) with Cu contacts is improved by spin-on-doping (SOD). The Si NWAs used in this work are fabricated via metal assisted chemical etching (MACE) of 0.01–0.02 Ω cm resistivity n- and p-type bulk, converting ~4% of the bulk thickness into NWs. The MACE process is adapted to ensure crystalline NWs. Current-voltage and Seebeck voltage-temperature measurements show that while SOD mainly influences the contact resistance in bulk, it influences both contact resistance and power factor in NWA-bulk based TEGs. According to our experiments, using Si NWAs in combination with SOD increases the output power by an order of 3 under the same heating power due to an increased power factor, decreased thermal conductivity of the NWA and reduced Si-Cu contact resistance.

  17. Progress in developing a thermal method for measuring the output power of medical ultrasound transducers that exploits the pyroelectric effect.

    PubMed

    Zeqiri, Bajram; Zauhar, Gordana; Hodnett, Mark; Barrie, Jill

    2011-05-01

    Progress in developing a new measurement method for ultrasound output power is described. It is a thermal-based technique with the acoustic power generated by a transducer being absorbed within a specially developed polyurethane rubber material, whose high absorption coefficient ensures energy deposition within a few mm of the ultrasonic wave entering the material. The rate of change of temperature at the absorber surface is monitored using the pyroelectric voltage generated from electrodes disposed either side of a 60 mm diameter, 0.061 mm thick membrane of the piezoelectric polymer polyvinylidene fluoride (pvdf) bonded to the absorber. The change in the pyroelectric output voltage generated by the sensor when the transducer is switched ON and OFF is proportional to the delivered ultrasound power. The sensitivity of the device is defined as the magnitude of these switch voltages to a unit input stimulus of power (watt). Three important aspects of the performance of the pyroelectric sensor have been studied. Firstly, measurements have revealed that the temperature dependent sensitivity increases over the range from approximately 20°C to 30°C at a rate of +1.6% °C(-1). Studies point to the key role that the properties of both the absorbing backing layer and pvdf membrane play in controlling the sensor response. Secondly, the high sensitivity of the technique has been demonstrated using an NPL Pulsed Checksource, a 3.5 MHz focused transducer delivering a nominal acoustic power level of 4 mW. Finally, proof-of-concept of a new type of acoustic sensor responding to time-averaged intensity has been demonstrated, through fabrication of an absorber-backed hydrophone of nominal active element diameter 0.4 mm. A preliminary study using such a device to resolve the spatial distribution of acoustic intensity within plane-piston and focused 3.5 MHz acoustic fields has been completed. Derived beam profiles are compared to conventional techniques that depend on deriving

  18. Submicron gate InP power MISFET's with improved output power density at 18 and 20 GHz

    NASA Technical Reports Server (NTRS)

    Biedenbender, M. D.; Kapoor, Vik J.; Shalkhauser, K. A.; Messick, L. J.; Nguyen, R.; Schmitz, D.; Juergensen, H.

    1991-01-01

    The microwave characteristics are presented at 18 and 20 GHz of submicron gate indium phosphide (InP) metal-insulator-semiconductor field-effect transistors (MISFET's) for high output power density applications. InP power MISFET's were fabricated and the output power density was investigated as a function of drain-source spacing. The best output power density and gain were obtained for drain-source spacing of 3 microns. The output power density is 2.7 times greater than was previously measured for InP MISFET's at 18 and 20 GHz, and the power-added efficiency also increased.

  19. Submicron gate InP power MISFET's with improved output power density at 18 and 20 GHz

    NASA Technical Reports Server (NTRS)

    Biedenbender, Michael D.; Kapoor, Vik J.; Shalkhauser, Kurt A.; Messick, Louis J.; Nguyen, Richard; Schmitz, Dietmar; Jurgensen, Holger

    1991-01-01

    The microwave characteristics are presented at 18 and 20 GHz of submicron gate indium phosphide (InP) metal-insulator-semiconductor field-effect transistors (MISFETs) for high output power density applications. InP power MISFET's were fabricated and the output power density was investigated as a function of drain-source spacing. The best output power density and gain were obtained for drain-source spacing of 3 micron. The output power density is 2.7 times greater than was previously measured for InP MISFET's at 18 and 20 GHz, and the power-added efficiency also increased.

  20. Muscle power output during escape responses in an Antarctic fish

    PubMed

    Franklin; Johnston

    1997-01-01

    Escape responses (C-shaped fast-starts) were filmed at 500 frames s-1 in the Antarctic rock cod (Notothenia coriiceps) at 0 °C. The activation and strain patterns of the superficial fast myotomal muscle were measured simultaneously using electromyography and sonomicrometry respectively. In order to bend the body into the initial C-shape, the muscle fibres in the rostral myotomes (at 0.35L, where L is total length) shortened by up to 13 % of their resting length at a maximum velocity of 1.68 fibre lengths s-1. During the contralateral contraction, muscle fibres were stretched (by 5 % and 7 % at 0.35L and 0.65L, respectively) and were activated prior to the end of lengthening, before shortening by up to 12 % of resting fibre length (peak-to-peak strain). Representative strain records were digitised to create cyclical events corresponding to the C-bend and contralateral contraction. Isolated fibres were subjected to the abstracted strain cycles and stimulated at the same point and for the same duration as occurs in vivo. During the early phase of shortening, muscle shortening velocity (V) increased dramatically whilst the load was relatively constant and represented a substantial fraction of the maximum isometric stress. Pre-stretch of active muscle was associated with significant force enhancement. For the contralateral contraction, V exceeded that predicted by the steady-state force­velocity relationship for considerable periods during each tailbeat, contributing to relatively high maximum instantaneous power outputs of up to 290 W kg-1 wet muscle mass. In vitro experiments, involving adjusting strain, cycle duration and stimulation parameters, indicated that in vivo muscle fibres produce close to their maximum power. During escape responses, the maximum velocity and acceleration recorded from the centre of gravity of the fish were 0.71±0.03 m s-1 and 17.1±1.4 m s-2, respectively (mean ± s.e.m., N=7 fish). Muscle performance was sufficient to produce maximum

  1. Multiple-input multiple-output (MIMO) analog-to-feature converter chipsets for sub-wavelength acoustic source localization and bearing estimation

    NASA Astrophysics Data System (ADS)

    Chakrabartty, Shantanu

    2010-04-01

    Localization of acoustic sources using miniature microphone arrays poses a significant challenge due to fundamental limitations imposed by the physics of sound propagation. With sub-wavelength distances between the microphones, resolving acute localization cues become difficult due to precision artifacts. In this work, we present the design of a miniature, microphone array sensor based on a patented Multiple-input Multiple-output (MIMO) analog-to-feature converter (AFC) chip-sets which overcomes the limitations due to precision artifacts. Measured results from fabricated prototypes demonstrate a bearing range of 0 degrees to 90 degrees with a resolution less than 2 degrees. The power dissipation of the MIMO-ADC chip-set for this task was measured to be less than 75 microwatts making it ideal for portable, battery powered sniper and gunshot detection applications.

  2. Ultrasonic power transfer from a spherical acoustic wave source to a free-free piezoelectric receiver: Modeling and experiment

    SciTech Connect

    Shahab, S.; Gray, M.; Erturk, A.

    2015-03-14

    Contactless powering of small electronic components has lately received growing attention for wireless applications in which battery replacement or tethered charging is undesired or simply impossible, and ambient energy harvesting is not a viable solution. As an alternative to well-studied methods of contactless energy transfer, such as the inductive coupling method, the use of ultrasonic waves transmitted and received by piezoelectric devices enables larger power transmission distances, which is critical especially for deep-implanted electronic devices. Moreover, energy transfer by means of acoustic waves is well suited in situations where no electromagnetic fields are allowed. The limited literature of ultrasonic acoustic energy transfer is mainly centered on proof-of-concept experiments demonstrating the feasibility of this method, lacking experimentally validated modeling efforts for the resulting multiphysics problem that couples the source and receiver dynamics with domain acoustics. In this work, we present fully coupled analytical, numerical, and experimental multiphysics investigations for ultrasonic acoustic energy transfer from a spherical wave source to a piezoelectric receiver bar that operates in the 33-mode of piezoelectricity. The fluid-loaded piezoelectric receiver under free-free mechanical boundary conditions is shunted to an electrical load for quantifying the electrical power output for a given acoustic source strength of the transmitter. The analytical acoustic-piezoelectric structure interaction modeling framework is validated experimentally, and the effects of system parameters are reported along with optimal electrical loading and frequency conditions of the receiver.

  3. An impulsive source with variable output and stable bandwidth for underwater acoustic experiments.

    PubMed

    McNeese, Andrew R; Wilson, Preston S; Sagers, Jason D; Knobles, David P

    2014-07-01

    The Combustive Sound Source (CSS) is being developed as an environmentally friendly source to be used in ocean acoustics research and surveys. It has the ability to maintain the same wide bandwidth signal over a 20 dB drop in source level. The CSS consists of a submersible combustion chamber filled with a fuel/oxidizer mixture. The mixture is ignited and the ensuing combustion and bubble activity radiates an impulsive, thus broadband, acoustic pulse. The ability to control pulse amplitude while maintaining bandwidth is demonstrated. PMID:24993239

  4. An impulsive source with variable output and stable bandwidth for underwater acoustic experiments.

    PubMed

    McNeese, Andrew R; Wilson, Preston S; Sagers, Jason D; Knobles, David P

    2014-07-01

    The Combustive Sound Source (CSS) is being developed as an environmentally friendly source to be used in ocean acoustics research and surveys. It has the ability to maintain the same wide bandwidth signal over a 20 dB drop in source level. The CSS consists of a submersible combustion chamber filled with a fuel/oxidizer mixture. The mixture is ignited and the ensuing combustion and bubble activity radiates an impulsive, thus broadband, acoustic pulse. The ability to control pulse amplitude while maintaining bandwidth is demonstrated.

  5. Steering by hearing: a bat's acoustic gaze is linked to its flight motor output by a delayed, adaptive linear law.

    PubMed

    Ghose, Kaushik; Moss, Cynthia F

    2006-02-01

    Adaptive behaviors require sensorimotor computations that convert information represented initially in sensory coordinates to commands for action in motor coordinates. Fundamental to these computations is the relationship between the region of the environment sensed by the animal (gaze) and the animal's locomotor plan. Studies of visually guided animals have revealed an anticipatory relationship between gaze direction and the locomotor plan during target-directed locomotion. Here, we study an acoustically guided animal, an echolocating bat, and relate acoustic gaze (direction of the sonar beam) to flight planning as the bat searches for and intercepts insect prey. We show differences in the relationship between gaze and locomotion as the bat progresses through different phases of insect pursuit. We define acoustic gaze angle, theta(gaze), to be the angle between the sonar beam axis and the bat's flight path. We show that there is a strong linear linkage between acoustic gaze angle at time t [theta(gaze)(t)] and flight turn rate at time t + tau into the future [theta(flight) (t + tau)], which can be expressed by the formula theta(flight) (t + tau) = ktheta(gaze)(t). The gain, k, of this linkage depends on the bat's behavioral state, which is indexed by its sonar pulse rate. For high pulse rates, associated with insect attacking behavior, k is twice as high compared with low pulse rates, associated with searching behavior. We suggest that this adjustable linkage between acoustic gaze and motor output in a flying echolocating bat simplifies the transformation of auditory information to flight motor commands.

  6. Examining the Variability of Wind Power Output in the Regulation Time Frame: Preprint

    SciTech Connect

    Hodge, B. M.; Shedd, S.; Florita, A.

    2012-08-01

    This work examines the distribution of changes in wind power for different time scales in the regulation time frame as well as the correlation of changes in power output for individual wind turbines in a wind plant.

  7. Method of measuring reactive acoustic power density in a fluid

    DOEpatents

    Wheatley, John C.; Swift, Gregory W.; Migliori, Albert

    1985-01-01

    A method for determining reactive acoustic power density level and its direction in a fluid using a single sensor is disclosed. In the preferred embodiment, an apparatus for conducting the method, which is termed a thermoacoustic couple, consists of a stack of thin, spaced apart polymeric plates, selected ones of which include multiple bimetallic thermocouple junctions positioned along opposite end edges thereof. The thermocouple junctions are connected in series in the nature of a thermopile, and are arranged so as to be responsive to small temperature differences between the opposite edges of the plates. The magnitude of the temperature difference, as represented by the magnitude of the electrical potential difference generated by the thermopile, is found to be directly related to the level of acoustic power density in the gas.

  8. Method of measuring reactive acoustic power density in a fluid

    DOEpatents

    Wheatley, J.C.; Swift, G.W.; Migliori, A.

    1985-09-03

    A method for determining reactive acoustic power density level and its direction in a fluid using a single sensor is disclosed. In the preferred embodiment, an apparatus for conducting the method, which is termed a thermoacoustic couple, consists of a stack of thin, spaced apart polymeric plates, selected ones of which include multiple bimetallic thermocouple junctions positioned along opposite end edges thereof. The thermocouple junctions are connected in series in the nature of a thermopile, and are arranged so as to be responsive to small temperature differences between the opposite edges of the plates. The magnitude of the temperature difference, as represented by the magnitude of the electrical potential difference generated by the thermopile, is found to be directly related to the level of acoustic power density in the gas. 5 figs.

  9. Method for leveling the power output of an electromechanical battery as a function of speed

    DOEpatents

    Post, Richard F.

    1999-01-01

    The invention is a method of leveling the power output of an electromechanical battery during its discharge, while at the same time maximizing its power output into a given load. The method employs the concept of series resonance, employing a capacitor the parameters of which are chosen optimally to achieve the desired near-flatness of power output over any chosen charged-discharged speed ratio. Capacitors are inserted in series with each phase of the windings to introduce capacitative reactances that act to compensate the inductive reactance of these windings. This compensating effect both increases the power that can be drawn from the generator before inductive voltage drops in the windings become dominant and acts to flatten the power output over a chosen speed range. The values of the capacitors are chosen so as to optimally flatten the output of the generator over the chosen speed range.

  10. Method for leveling the power output of an electromechanical battery as a function of speed

    DOEpatents

    Post, R.F.

    1999-03-16

    The invention is a method of leveling the power output of an electromechanical battery during its discharge, while at the same time maximizing its power output into a given load. The method employs the concept of series resonance, employing a capacitor the parameters of which are chosen optimally to achieve the desired near-flatness of power output over any chosen charged-discharged speed ratio. Capacitors are inserted in series with each phase of the windings to introduce capacitative reactances that act to compensate the inductive reactance of these windings. This compensating effect both increases the power that can be drawn from the generator before inductive voltage drops in the windings become dominant and acts to flatten the power output over a chosen speed range. The values of the capacitors are chosen so as to optimally flatten the output of the generator over the chosen speed range. 3 figs.

  11. Halbach array generator/motor having an automatically regulated output voltage and mechanical power output

    DOEpatents

    Post, Richard F.

    2005-02-22

    A motor/generator having its stationary portion, i.e., the stator, positioned concentrically within its rotatable element, i.e., the rotor, along its axis of rotation. The rotor includes a Halbach array. The stator windings are switched or commutated to provide a DC motor/generator much the same as in a conventional DC motor/generator. The voltage and power are automatically regulated by using centrifugal force to change the diameter of the rotor, and thereby vary the radial gap in between the stator and the rotating Halbach array, as a function of the angular velocity of the rotor.

  12. Magnetic Bearing Amplifier Output Power Filters for Flywheel Systems

    NASA Technical Reports Server (NTRS)

    Lebron-Velilla, Ramon C.; Jansen, Ralph H.; Palazzolo, Alan; Thomas, Erwin; Kascak, Peter E.; Birchenough, Arthur G.; Dever, Timothy P.

    2003-01-01

    Five power filters and two types of power amplifiers were tested for use with active magnetic bearings for flywheel applications. Filter topologies included low pass filters and low pass filters combined with trap filters at the PWM switching frequency. Two state and three state PWM amplifiers were compared. Each system was evaluated based on current magnitude at the switching frequency, voltage magnitude at 500 kHz, and power consumption. The base line system was a two state amplifier without a power filter. The recommended system is a three state power amplifier with a 50 kHz low pass filter and a 27 kHz trap filter. This system uses 5.57 W. It reduces the switching current by an order of magnitude and the 500 kHz voltage by two orders of magnitude. The relative power consumption varied depending on the test condition between 60 to 130 percent of the baseline.

  13. Power Converters Maximize Outputs Of Solar Cell Strings

    NASA Technical Reports Server (NTRS)

    Frederick, Martin E.; Jermakian, Joel B.

    1993-01-01

    Microprocessor-controlled dc-to-dc power converters devised to maximize power transferred from solar photovoltaic strings to storage batteries and other electrical loads. Converters help in utilizing large solar photovoltaic arrays most effectively with respect to cost, size, and weight. Main points of invention are: single controller used to control and optimize any number of "dumb" tracker units and strings independently; power maximized out of converters; and controller in system is microprocessor.

  14. Finding the quantum thermoelectric with maximal efficiency and minimal entropy production at given power output

    NASA Astrophysics Data System (ADS)

    Whitney, Robert S.

    2015-03-01

    We investigate the nonlinear scattering theory for quantum systems with strong Seebeck and Peltier effects, and consider their use as heat engines and refrigerators with finite power outputs. This paper gives detailed derivations of the results summarized in a previous paper [R. S. Whitney, Phys. Rev. Lett. 112, 130601 (2014), 10.1103/PhysRevLett.112.130601]. It shows how to use the scattering theory to find (i) the quantum thermoelectric with maximum possible power output, and (ii) the quantum thermoelectric with maximum efficiency at given power output. The latter corresponds to a minimal entropy production at that power output. These quantities are of quantum origin since they depend on system size over electronic wavelength, and so have no analog in classical thermodynamics. The maximal efficiency coincides with Carnot efficiency at zero power output, but decreases with increasing power output. This gives a fundamental lower bound on entropy production, which means that reversibility (in the thermodynamic sense) is impossible for finite power output. The suppression of efficiency by (nonlinear) phonon and photon effects is addressed in detail; when these effects are strong, maximum efficiency coincides with maximum power. Finally, we show in particular limits (typically without magnetic fields) that relaxation within the quantum system does not allow the system to exceed the bounds derived for relaxation-free systems, however, a general proof of this remains elusive.

  15. Technique for enhancing the power output of an electrostatic generator employing parametric resonance

    DOEpatents

    Post, Richard F.

    2016-02-23

    A circuit-based technique enhances the power output of electrostatic generators employing an array of axially oriented rods or tubes or azimuthal corrugated metal surfaces for their electrodes. During generator operation, the peak voltage across the electrodes occurs at an azimuthal position that is intermediate between the position of minimum gap and maximum gap. If this position is also close to the azimuthal angle where the rate of change of capacity is a maximum, then the highest rf power output possible for a given maximum allowable voltage at the minimum gap can be attained. This rf power output is then coupled to the generator load through a coupling condenser that prevents suppression of the dc charging potential by conduction through the load. Optimized circuit values produce phase shifts in the rf output voltage that allow higher power output to occur at the same voltage limit at the minimum gap position.

  16. Power cepstrum technique with application to model helicopter acoustic data

    NASA Technical Reports Server (NTRS)

    Martin, R. M.; Burley, C. L.

    1986-01-01

    The application of the power cepstrum to measured helicopter-rotor acoustic data is investigated. A previously applied correction to the reconstructed spectrum is shown to be incorrect. For an exact echoed signal, the amplitude of the cepstrum echo spike at the delay time is linearly related to the echo relative amplitude in the time domain. If the measured spectrum is not entirely from the source signal, the cepstrum will not yield the desired echo characteristics and a cepstral aliasing may occur because of the effective sample rate in the frequency domain. The spectral analysis bandwidth must be less than one-half the echo ripple frequency or cepstral aliasing can occur. The power cepstrum editing technique is a useful tool for removing some of the contamination because of acoustic reflections from measured rotor acoustic spectra. The cepstrum editing yields an improved estimate of the free field spectrum, but the correction process is limited by the lack of accurate knowledge of the echo transfer function. An alternate procedure, which does not require cepstral editing, is proposed which allows the complete correction of a contaminated spectrum through use of both the transfer function and delay time of the echo process.

  17. Flow lasers. [fluid mechanics of high power continuous output operations

    NASA Technical Reports Server (NTRS)

    Christiansen, W. H.; Russell, D. A.; Hertzberg, A.

    1975-01-01

    The present work reviews the fluid-mechanical aspects of high-power continuous-wave (CW) lasers. The flow characteristics of these devices appear as classical fluid-mechanical phenomena recast in a complicated interactive environment. The fundamentals of high-power lasers are reviewed, followed by a discussion of the N2-CO2 gas dynamic laser. Next, the HF/DF supersonic diffusion laser is described, and finally the CO electrical-discharge laser is discussed.

  18. Klamath Falls: High-Power Acoustic Well Stimulation Technology

    SciTech Connect

    Black, Brian

    2006-07-24

    Acoustic well stimulation (AWS) technology uses high-power sonic waves from specific frequency spectra in an attempt to stimulate production in a damaged or low-production wellbore. AWS technology is one of the most promising technologies in the oil and gas industry, but it has proven difficult for the industry to develop an effective downhole prototype. This collaboration between Klamath Falls Inc. and the Rocky Mountain Oilfield Testing Center (RMOTC) included a series of tests using high-power ultrasonic tools to stimulate oil and gas production. Phase I testing was designed and implemented to verify tool functionality, power requirements, and capacity of high-power AWS tools. The purpose of Phase II testing was to validate the production response of wells with marginal production rates to AWS stimulation and to capture and identify any changes in the downhole environment after tool deployment. This final report presents methodology and results.

  19. Validation of Power Output for the WIND Toolkit

    SciTech Connect

    King, J.; Clifton, A.; Hodge, B. M.

    2014-09-01

    Renewable energy integration studies require wind data sets of high quality with realistic representations of the variability, ramping characteristics, and forecast performance for current wind power plants. The Wind Integration National Data Set (WIND) Toolkit is meant to be an update for and expansion of the original data sets created for the weather years from 2004 through 2006 during the Western Wind and Solar Integration Study and the Eastern Wind Integration Study. The WIND Toolkit expands these data sets to include the entire continental United States, increasing the total number of sites represented, and it includes the weather years from 2007 through 2012. In addition, the WIND Toolkit has a finer resolution for both the temporal and geographic dimensions. Three separate data sets will be created: a meteorological data set, a wind power data set, and a forecast data set. This report describes the validation of the wind power data set.

  20. Electrical power converter method and system employing multiple output converters

    DOEpatents

    Beihoff, Bruce C.; Radosevich, Lawrence D.; Meyer, Andreas A.; Gollhardt, Neil; Kannenberg, Daniel G.

    2007-05-01

    A support may receive one or more power electronic circuits. The support may aid in removing heat from the circuits through fluid circulating through the support. The support, in conjunction with other packaging features may form a shield from both external EMI/RFI and from interference generated by operation of the power electronic circuits. Features may be provided to permit and enhance connection of the circuitry to external circuitry, such as improved terminal configurations. Modular units may be assembled that may be coupled to electronic circuitry via plug-in arrangements or through interface with a backplane or similar mounting and interconnecting structures.

  1. Computer controlled pump unit cuts power, increases output

    SciTech Connect

    Rosman, A.; Nofal, M.

    1996-11-01

    OroNegro, Inc., a small, high-tech Southern California operating company with a stated mission to find and utilize innovations that lower production costs, adopted that philosophy in applying a new sucker rod pumping system in its shallow, heavy oil fields in Newhall and Bakersfield, California. Six new hydraulic, computer-controlled pumping (CCP) units developed and supplied by DynaPump, Inc., also of Southern California, have been installed, and are producing significant operating and economic benefits. Basic CCP unit features include a very long stroke with a charged gas (nitrogen) counterbalance and automatic computer-controlled speed, to maximize flow. In one case described, an industry-standard 456 (456,000 in. lb torque), 100-hp unit was replaced by a 60-hp CCP unit, nearly doubling pump output. Field installations and pumping systems in Newhall field, and tests in Kern Front field are described, along with the operator`s views on other CCP applications, including its use in deep wells.

  2. Performance of improved magnetostrictive vibrational power generator, simple and high power output for practical applications

    SciTech Connect

    Ueno, Toshiyuki

    2015-05-07

    Vibration based power generation technology is utilized effectively in various fields. Author has invented novel vibrational power generation device using magnetostrictive material. The device is based on parallel beam structure consisting of a rod of iron-gallium alloy wound with coil and yoke accompanied with permanent magnet. When bending force is applied on the tip of the device, the magnetization inside the rod varies with induced stress due to the inverse magnetostrictive effect. In vibration, the time variation of the magnetization generates voltage on the wound coil. The magnetostrictive type is advantageous over conventional such using piezoelectric or moving magnet types in high efficiency and high robustness, and low electrical impedance. Here, author has established device configuration, simple, rigid, and high power output endurable for practical applications. In addition, the improved device is lower cost using less volume of Fe-Ga and permanent magnet compared to our conventional, and its assembly by soldering is easy and fast suitable for mass production. Average power of 3 mW/cm{sup 3} under resonant vibration of 212 Hz and 1.2 G was obtained in miniature prototype using Fe-Ga rod of 2 × 0.5× 7 mm{sup 3}. Furthermore, the damping effect was observed, which demonstrates high energy conversion of the generator.

  3. Power Amplifier Module with 734-mW Continuous Wave Output Power

    NASA Technical Reports Server (NTRS)

    Fung, King Man; Samoska, Lorene A.; Kangaslahti, Pekka P.; Lamgrigtsen, Bjorn H.; Goldsmith, Paul F.; Lin, Robert H.; Soria, Mary M.; Cooperrider, Joelle T.; Micovic, Moroslav; Kurdoghlian, Ara

    2010-01-01

    Research findings were reported from an investigation of new gallium nitride (GaN) monolithic millimeter-wave integrated circuit (MMIC) power amplifiers (PAs) targeting the highest output power and the highest efficiency for class-A operation in W-band (75-110 GHz). W-band PAs are a major component of many frequency multiplied submillimeter-wave LO signal sources. For spectrometer arrays, substantial W-band power is required due to the passive lossy frequency multipliers-to generate higher frequency signals in nonlinear Schottky diode-based LO sources. By advancing PA technology, the LO system performance can be increased with possible cost reductions compared to current GaAs PAs. High-power, high-efficiency GaN PAs are cross-cutting and can enable more efficient local oscillator distribution systems for new astrophysics and planetary receivers and heterodyne array instruments. It can also allow for a new, electronically scannable solid-state array technology for future Earth science radar instruments and communications platforms.

  4. Human muscle power output during upper- and lower-body exercises.

    PubMed

    Siegel, Judith A; Gilders, Roger M; Staron, Robert S; Hagerman, Frederick C

    2002-05-01

    The purpose of this study was to evaluate the use of traditional resistance training equipment in the measurement of muscular power. This was accomplished by measuring the velocity of movement through a measured distance during maximal effort lifts using a Smith rack. The reliability of the method was established using 10 male volunteers who performed both bench press and squat exercises in a Smith rack. Maximal power output was determined at 30, 40, 50, 60, 70, 80, and 90% of the subject's 1 repetition maximum (1RM). Test-retest power values were not statistically different. Another 15 male volunteers who had previous muscle biopsy data from the vastus lateralis muscle performed the same maximal power output evaluation. There were no significant relationships between peak power outputs and fiber-type expressions when linear regressions were performed. The power curve produced by graphing power output vs. the percentage of 1RM indicates that peak power output occurs between 50 and 70% of 1RM for the squat and between 40 and 60% of 1RM for the bench press. These data indicate that this method of evaluation of muscle power is reliable, although it is not predictive of muscle fiber-type percentages. PMID:11991767

  5. Reversing pathologically increased EEG power by acoustic coordinated reset neuromodulation

    PubMed Central

    Adamchic, Ilya; Toth, Timea; Hauptmann, Christian; Tass, Peter Alexander

    2014-01-01

    Acoustic Coordinated Reset (CR) neuromodulation is a patterned stimulation with tones adjusted to the patient's dominant tinnitus frequency, which aims at desynchronizing pathological neuronal synchronization. In a recent proof-of-concept study, CR therapy, delivered 4–6 h/day more than 12 weeks, induced a significant clinical improvement along with a significant long-lasting decrease of pathological oscillatory power in the low frequency as well as γ band and an increase of the α power in a network of tinnitus-related brain areas. As yet, it remains unclear whether CR shifts the brain activity toward physiological levels or whether it induces clinically beneficial, but nonetheless abnormal electroencephalographic (EEG) patterns, for example excessively decreased δ and/or γ. Here, we compared the patients' spontaneous EEG data at baseline as well as after 12 weeks of CR therapy with the spontaneous EEG of healthy controls by means of Brain Electrical Source Analysis source montage and standardized low-resolution brain electromagnetic tomography techniques. The relationship between changes in EEG power and clinical scores was investigated using a partial least squares approach. In this way, we show that acoustic CR neuromodulation leads to a normalization of the oscillatory power in the tinnitus-related network of brain areas, most prominently in temporal regions. A positive association was found between the changes in tinnitus severity and the normalization of δ and γ power in the temporal, parietal, and cingulate cortical regions. Our findings demonstrate a widespread CR-induced normalization of EEG power, significantly associated with a reduction of tinnitus severity. PMID:23907785

  6. Electromagnetic system for the management of the output power of the carbon dioxide laser

    NASA Astrophysics Data System (ADS)

    Martsinukov, S. A.; Kostrin, D. K.; Chernigovskiy, V. V.; Lisenkov, A. A.

    2016-07-01

    The methods to control the output power of the gas-discharge lasers are shown. An electromagnetic system for the management of the output power of the carbon dioxide laser is described. The results of calculation and modeling of the magnetic field in the working gap of the electromagnetic system are presented. Experimental studies on the distribution of magnetic induction in the electromagnetic system are carried out.

  7. Water Power Calculator Temperature and Analog Input/Output Module Ambient Temperature Testing

    SciTech Connect

    Mark D. McKay

    2011-02-01

    Water Power Calculator Temperature and Analog input/output Module Ambient Temperature Testing A series of three ambient temperature tests were conducted for the Water Power Calculator development using the INL Calibration Laboratory’s Tenney Environmental Chamber. The ambient temperature test results demonstrate that the Moore Industries Temperature Input Modules, Analog Input Module and Analog Output Module, ambient temperature response meet or exceed the manufactures specifications

  8. Effect of interrepetition rest intervals on weight training repetition power output.

    PubMed

    Lawton, Trent W; Cronin, John B; Lindsell, Rod P

    2006-02-01

    The purpose of this study was to determine the change in weight training repetition power output as a consequence of interrepetition rest intervals. Twenty-six elite junior male basketball and soccer players performed bench presses using a 6 repetition maximum (6RM) load. The power output for each repetition was recorded using a linear encoder sampling each 10 ms (100 Hz). Subjects were assigned to 1 of 3 intervention groups, differentiated by the arrangement of rest intervals within the 6 repetitions: 6 x 1 repetition with 20-second rest periods between each repetition (Singles); 3 x 2 repetitions with 50 seconds between each pair of repetitions (Doubles); or 2 x 3 repetitions with 100 seconds of rest between each 3 repetitions (Triples). A timer was used to ensure that the rest interval and duration to complete all interrepetition interventions was equated across groups (118 seconds). Significantly (p < 0.05) greater repetition power outputs (25-49%) were observed in the later repetitions (4-6) of the Singles, Doubles, and Triples loading schemes. Significantly greater total power output (21.6-25.1%) was observed for all interrepetition rest interventions when compared to traditional continuous 6RM total power output. No significant between-group differences were found (p = 0.96). We conclude that utilizing interrepetition rest intervals enables greater repetition and total power output in comparison to traditional loading parameters.

  9. Gyrotron Output Power Stabilization by PID Feedback Control of Heater Current and Anode Voltage

    NASA Astrophysics Data System (ADS)

    Khutoryan, E. M.; Idehara, T.; Kuleshov, A. N.; Ueda, K.

    2014-12-01

    To provide stable output power of a gyrotron during long operation time the power stabilization was achieved by two schemes with PID feedback control of heater current and anode voltage. It was based on the dependence of the output power on both the anode voltage and the beam current and also on the dependence of the beam current on the gun heater current. Both schemes provided decrease of the power standard deviation to 0.3-0.5%. The comparison between parameters of both schemes is discussed in the paper.

  10. Temperature dependence of optically dumped far-infrared (FIR) laser output power

    NASA Technical Reports Server (NTRS)

    Lawandy, N. M.

    1978-01-01

    The temperature dependence of the small signal gain and saturation power are derived using temperature-dependent rates in a four-level model. An expression is developed for the output power of a far-infrared oscillator as a function of temperature for both fixed pressure and fixed density. The results are valid in the regime of homogeneous broadening of the rotational transition and Doppler broadening of the pump transition. It is shown that, for most lasers, both the small signal gain and the saturation power decrease with increasing temperature. These effects have the overall result of increasing output power with decreasing temperatures.

  11. Power output of offshore wind farms in relation to atmospheric stability

    NASA Astrophysics Data System (ADS)

    Alblas, Laurens; Bierbooms, Wim; Veldkamp, Dick

    2014-12-01

    Atmospheric stability is known to influence wind farm power output, by affecting power losses due to wakes. This research tries to answer what atmospheric stability does to the power production and how conventional simulations using the Jensen wake model compare and can be improved. Data is used from two offshore wind farms, Egmond aan Zee (OWEZ) and North Hoyle. Stability distributions are determined using metmast data. By combining this data with the production data, the influence of stability on the power output is studied. It is found that very unstable conditions result in higher power output (i.e. smaller wake losses) than near-neutral conditions, and these again show higher power output than during very stable conditions. Differences in normalized power output of 10-20% exist between the very unstable and very stable conditions. Simulations can be improved by adapting the wake decay constant (WDC). Observed WDC values are k >= TI, as opposed to the conventional k ≈ 0.5TI. A hypothesis for further research is proposed regarding the influence of vertical turbulence.

  12. Influence of output power of a spin torque oscillator on phase locked loop operation

    NASA Astrophysics Data System (ADS)

    Tamaru, Shingo; Kubota, Hitoshi; Yakushiji, Kay; Fukushima, Akio; Yuasa, Shinji

    2016-09-01

    This work investigates the influence of the output power of a spin torque oscillator (STO) on the operation of a phase locked loop (PLL) circuit. Timing jitter and minimum output power for stable PLL operation determined by Johnson noise and shot noise are first theoretically calculated, and compared with experimental results. The theory and experiment show a reasonably good agreement, indicating that smaller than -50 dBm (10 nW), or -60 dBm (1 nW) when a low pass filter is used, of output power is sufficient for stable PLL operation if a large timing jitter is acceptable. However, it is also shown that a large output power is needed to suppress timing jitter down to the level comparable to state-of-the-art commercial PLL circuits. The estimate of minimum output power for stable PLL operation is verified by intentionally attenuating the STO output signal down to -55 dBm (3.2 nW) and demonstrating a stable phase locked oscillation.

  13. Influence of output power of a spin torque oscillator on phase locked loop operation

    NASA Astrophysics Data System (ADS)

    Tamaru, Shingo; Kubota, Hitoshi; Yakushiji, Kay; Fukushima, Akio; Yuasa, Shinji

    2016-09-01

    This work investigates the influence of the output power of a spin torque oscillator (STO) on the operation of a phase locked loop (PLL) circuit. Timing jitter and minimum output power for stable PLL operation determined by Johnson noise and shot noise are first theoretically calculated, and compared with experimental results. The theory and experiment show a reasonably good agreement, indicating that smaller than ‑50 dBm (10 nW), or ‑60 dBm (1 nW) when a low pass filter is used, of output power is sufficient for stable PLL operation if a large timing jitter is acceptable. However, it is also shown that a large output power is needed to suppress timing jitter down to the level comparable to state-of-the-art commercial PLL circuits. The estimate of minimum output power for stable PLL operation is verified by intentionally attenuating the STO output signal down to ‑55 dBm (3.2 nW) and demonstrating a stable phase locked oscillation.

  14. Optimal cycling time trial position models: aerodynamics versus power output and metabolic energy.

    PubMed

    Fintelman, D M; Sterling, M; Hemida, H; Li, F-X

    2014-06-01

    The aerodynamic drag of a cyclist in time trial (TT) position is strongly influenced by the torso angle. While decreasing the torso angle reduces the drag, it limits the physiological functioning of the cyclist. Therefore the aims of this study were to predict the optimal TT cycling position as function of the cycling speed and to determine at which speed the aerodynamic power losses start to dominate. Two models were developed to determine the optimal torso angle: a 'Metabolic Energy Model' and a 'Power Output Model'. The Metabolic Energy Model minimised the required cycling energy expenditure, while the Power Output Model maximised the cyclists׳ power output. The input parameters were experimentally collected from 19 TT cyclists at different torso angle positions (0-24°). The results showed that for both models, the optimal torso angle depends strongly on the cycling speed, with decreasing torso angles at increasing speeds. The aerodynamic losses outweigh the power losses at cycling speeds above 46km/h. However, a fully horizontal torso is not optimal. For speeds below 30km/h, it is beneficial to ride in a more upright TT position. The two model outputs were not completely similar, due to the different model approaches. The Metabolic Energy Model could be applied for endurance events, while the Power Output Model is more suitable in sprinting or in variable conditions (wind, undulating course, etc.). It is suggested that despite some limitations, the models give valuable information about improving the cycling performance by optimising the TT cycling position.

  15. Continuous-wave 193.4 nm laser with 120 mW output power.

    PubMed

    Sakuma, Jun; Kaneda, Yushi; Oka, Naoya; Ishida, Takayuki; Moriizumi, Koichi; Kusunose, Haruhiko; Furukawa, Yasunori

    2015-12-01

    This Letter describes an all-solid-state continuous-wave, deep-ultraviolet coherent source that generates more than 100 mW of output power at 193.4 nm. The source is based on nonlinear frequency conversion of three single-frequency infrared fiber laser master-oscillator power-amplifier (MOPA) light sources.

  16. Investigating temperature degradation in THz quantum cascade lasers by examination of temperature dependence of output power

    SciTech Connect

    Albo, Asaf Hu, Qing

    2015-03-30

    In this paper, we demonstrate a method to investigate the temperature degradation of THz quantum cascade lasers (QCLs) based on analyzing the dependence of lasing output power on temperature. The output power is suggested to decrease exponentially with some characteristic activation energy indicative of the degradation mechanism. As a proof of concept, Arrhenius plots of power versus temperature are used to extract the activation energy in vertical transition THz QCLs. The extracted energies are consistent with thermally activated longitudinal optical-phonon scattering being the dominant degradation mechanism, as is generally accepted. The extracted activation energy values are shown to be in good agreement with the values predicted from laser spectra.

  17. Effects on nonlinearity on the estimation of in situ values of acoustic output parameters.

    PubMed

    Szabo, T L; Clougherty, F; Grossman, C

    1999-01-01

    Water can generate extreme waveform distortion compared to tissue, as indicated by the Goldberg number for water, which is 20 times larger than that of tissue at typical diagnostic ultrasound levels. This result was demonstrated by using tofu as a tissue mimicking material. By adjusting transducer voltage drive levels in water to match the peak rarefactional pressures in water to those of waveforms in tofu, a close correspondence was obtained for the peak compressional pressure and time average intensity with depth. A poorer correspondence was found by comparing tofu waveforms with water waveforms that were compensated for broadband attenuation and driven at the same voltage level as tofu. A simplified broadband derating factor, allowing for band-width adjustment, was shown to be more accurate than the standard monochromatic derating. Several new indicators for quantifying the degree of observed nonlinearity are suggested: a field based nonlinearity parameter, a peak pressure ratio pc/pr, and a second harmonic to fundamental frequency spectral ratio. These indicators may have the potential for more consistent characterization of nonlinear relationships among output parameters and drive levels. PMID:9952078

  18. Effective channel estimation and efficient symbol detection for multi-input multi-output underwater acoustic communications

    NASA Astrophysics Data System (ADS)

    Ling, Jun

    Achieving reliable underwater acoustic communications (UAC) has long been recognized as a challenging problem owing to the scarce bandwidth available and the reverberant spread in both time and frequency domains. To pursue high data rates, we consider a multi-input multi-output (MIMO) UAC system, and our focus is placed on two main issues regarding a MIMO UAC system: (1) channel estimation, which involves the design of the training sequences and the development of a reliable channel estimation algorithm, and (2) symbol detection, which requires interference cancelation schemes due to simultaneous transmission from multiple transducers. To enhance channel estimation performance, we present a cyclic approach for designing training sequences with good auto- and cross-correlation properties, and a channel estimation algorithm called the iterative adaptive approach (IAA). Sparse channel estimates can be obtained by combining IAA with the Bayesian information criterion (BIC). Moreover, we present sparse learning via iterative minimization (SLIM) and demonstrate that SLIM gives similar performance to IAA but at a much lower computational cost. Furthermore, an extension of the SLIM algorithm is introduced to estimate the sparse and frequency modulated acoustic channels. The extended algorithm is referred to as generalization of SLIM (GoSLIM). Regarding symbol detection, a linear minimum mean-squared error based detection scheme, called RELAX-BLAST, which is a combination of vertical Bell Labs layered space-time (V-BLAST) algorithm and the cyclic principle of the RELAX algorithm, is presented and it is shown that RELAX-BLAST outperforms V-BLAST. We show that RELAX-BLAST can be implemented efficiently by making use of the conjugate gradient method and diagonalization properties of circulant matrices. This fast implementation approach requires only simple fast Fourier transform operations and facilitates parallel implementations. The effectiveness of the proposed MIMO schemes

  19. A combined compensation method for the output voltage of an insulated core transformer power supply

    NASA Astrophysics Data System (ADS)

    Yang, L.; Yang, J.; Liu, K. F.; Qin, B.; Chen, D. Z.

    2014-06-01

    An insulated core transformer (ICT) power supply is an ideal high-voltage generator for irradiation accelerators with energy lower than 3 MeV. However, there is a significant problem that the structure of the segmented cores leads to an increase in the leakage flux and voltage differences between rectifier disks. A high level of consistency in the output of the disks helps to achieve a compact structure by improving the utilization of both the rectifier components and the insulation distances, and consequently increase the output voltage of the power supply. The output voltages of the disks which are far away from the primary coils need to be improved to reduce their inhomogeneity. In this study, by investigating and comparing the existing compensation methods, a new combined compensation method is proposed, which increases the turns on the secondary coils and employs parallel capacitors to improve the consistency of the disks, while covering the entire operating range of the power supply. This method turns out to be both feasible and effective during the development of an ICT power supply. The non-uniformity of the output voltages of the disks is less than 3.5% from no-load to full-load, and the power supply reaches an output specification of 350 kV/60 mA.

  20. The effect of pedaling cadence and power output on mechanomyographic amplitude and mean power frequency during submaximal cycle ergometry.

    PubMed

    Hendrix, C R; Bull, A J; Housh, T J; Rana, S R; Cramer, J T; Beck, T W; Weir, J P; Malek, M H; Mielke, M

    2008-01-01

    The purpose of this study was to examine the effects of power output and pedaling cadence on the amplitude and mean power frequency (MPF) of the mechanomyographic (MMG) signal during submaximal cycle ergometry. Nine adults (mean age +/- SD = 22.7 +/- 2.1 yrs) performed an incremental (25 W increase every min) test to exhaustion on an electronically braked cycle ergometer to determine VO2Peak and Wpeak. The subjects also performed three, 8 min continuous, constant power output rides (randomly ordered) at 35%, 50%, and 65% Wpeak. The continuous 8 min workbouts were divided into 4 min epochs. The subjects pedaled at either 50 or 70 rev x min(-1) (randomized) during the first 4 min epoch, then changed to the alternate cadence during the second 4 min epoch. The MMG signal was recorded from the vastus lateralis during the final 10 s of each minute. Two separate two-way [cadence (50 and 70 rev x min(-1)) x %Wpeak (35, 50, and 65)] repeated measures ANOVAs indicated that MMG amplitude followed power output, but not pedaling cadence, whereas MMG MPF was not consistently affected by power output or pedaling cadence. Furthermore, these findings suggested that power output was modulated by motor unit recruitment and not rate coding.

  1. A new approach to controlling the ytterbium fibre laser output power

    SciTech Connect

    Voronin, V G; Nanii, Oleg E; Sus'yan, A A; Khlystov, V I

    2010-02-28

    A new approach has been proposed for controlling the linearly polarised output of an ytterbium-doped double-clad fibre laser: inverted-population modulation via loss modulation in a competing channel. The steady-state output power of the working channel has been determined as a function of loss in the competing channel. The results are qualitatively interpreted in terms of standard models of a dual-channel laser.

  2. Acoustic intensity near a high-powered military jet aircraft.

    PubMed

    Stout, Trevor A; Gee, Kent L; Neilsen, Tracianne B; Wall, Alan T; James, Michael M

    2015-07-01

    The spatial variation in vector acoustic intensity has been calculated between 100 and 3000 Hz near a high-performance military aircraft. With one engine of a tethered F-22A Raptor operating at military power, a tetrahedral intensity probe was moved to 27 locations in the geometric near and mid-fields to obtain the frequency-dependent intensity vector field. The angles of the maximum intensity region rotate from aft to sideline with increasing frequency, becoming less directional above 800 Hz. Between 100 and 400 Hz, which are principal radiation frequencies, the ray-traced dominant source region rapidly contracts and moves upstream, approaching nearly constant behavior by 1000 Hz. PMID:26233049

  3. Acoustic intensity near a high-powered military jet aircraft.

    PubMed

    Stout, Trevor A; Gee, Kent L; Neilsen, Tracianne B; Wall, Alan T; James, Michael M

    2015-07-01

    The spatial variation in vector acoustic intensity has been calculated between 100 and 3000 Hz near a high-performance military aircraft. With one engine of a tethered F-22A Raptor operating at military power, a tetrahedral intensity probe was moved to 27 locations in the geometric near and mid-fields to obtain the frequency-dependent intensity vector field. The angles of the maximum intensity region rotate from aft to sideline with increasing frequency, becoming less directional above 800 Hz. Between 100 and 400 Hz, which are principal radiation frequencies, the ray-traced dominant source region rapidly contracts and moves upstream, approaching nearly constant behavior by 1000 Hz.

  4. Determination of the acoustic source power levels of wind turbines

    NASA Astrophysics Data System (ADS)

    Debruijn, A.; Stam, W. J.; Dewolf, W. B.

    To facilitate Wind Energy Conversin System (WECS) licensing, it is recommended to obtain the immission-relevant sound power from the WECS, since this quantity fits into most recommendations for industrial installations. Measurements on small and medium-scale WECS show that rotor rotation speed is a more important parameter than the wind velocity with regard to the radiated noise. An acoustic telescope was used to identify noise sources on two medium-size wind turbines. The mechanical noise from the nacelle is mostly predominant but the trailing edge aerodynamic noise is not negligible. A prediction model for this type of noise, which leads to good agreement with experimental data was developed. A method to suppress turbulence signals around WECS is a set-up with twin microphones, using correlation techniques on both signals.

  5. Effects of heat exposure in the absence of hyperthermia on power output during repeated cycling sprints

    PubMed Central

    Arimitsu, T; Yunoki, T; Kimura, T; Yamanaka, R; Yano, T

    2014-01-01

    The aim of this study was to investigate the effects of heat exposure in the absence of hyperthermia on power output during repeated cycling sprints. Seven males performed four 10-s cycling sprints interspersed by 30 s of active recovery on a cycle ergometer in hot-dry and thermoneutral environments. Changes in rectal temperature were similar under the two ambient conditions. The mean 2-s power output over the 1st–4th sprints was significantly lower under the hot-dry condition than under the thermoneutral condition. The amplitude of the electromyogram was lower under the hot-dry condition than under the thermoneutral condition during the early phase (0–3 s) of each cycling sprint. No significant difference was observed for blood lactate concentration between the two ambient conditions. Power output at the onset of a cycling sprint during repeated cycling sprints is decreased due to heat exposure in the absence of hyperthermia. PMID:25729145

  6. High-power Er:YAG laser with quasi-top-hat output beam.

    PubMed

    Kim, J W; Mackenzie, J I; Hayes, J R; Clarkson, W A

    2012-05-01

    A simple method for simultaneously exciting the fundamental (TEM00) transverse mode and first order Laguerre-Gaussian (LG01) donut mode in an end-pumped solid-state laser to yield a quasi-top-hat output beam is reported. This approach has been applied to an Er:YAG laser, in-band pumped by an Er,Yb fiber laser, yielding 9.6 W of continuous-wave output at 1645 nm in a top-hat-like beam with beam propagation factor (M2)<2.1 for 24 W of incident pump power at 1532 nm. The corresponding slope efficiency with respect to incident pump power was 49%. The prospects of further scaling of output power and improved overall efficiency are considered.

  7. Anomalous TWTA output power spikes and their effect on a digital satellite communications system

    NASA Technical Reports Server (NTRS)

    May, Brian D.; Kerczewski, Robert J.; Svoboda, James S.

    1992-01-01

    Several 30 GHz, 60 W traveling wave tube amplifiers (TWTA) were manufactured for the NASA Lewis Research Center's High Burst Rate Link Evaluation Terminal Project. An unusual operating problem characterized by anomalous nonperiodic output power spikes, common to all of the TWTAs proved during testing to significantly affect the performance of a digitally-modulated data transmission test system. Modifications made to the TWTAs significantly curtailed the problem and allowed acceptable system performance to be obtained. This paper presents a discussion of the TWTA output power spike problem, possible causes of the problem, and the solutions implemented by the manufacturer which improved the TWTA performance to an acceptable level. The results of the testing done at NASA Lewis on the TWTAs both before and after the improvement made by Hughes are presented, and the effects of the output power spikes on the performance of the test system are discussed.

  8. Acute effect of static stretching on power output during concentric dynamic constant external resistance leg extension.

    PubMed

    Yamaguchi, Taichi; Ishii, Kojiro; Yamanaka, Masanori; Yasuda, Kazunori

    2006-11-01

    The purpose of the present study was to clarify the effect of static stretching on muscular performance during concentric isotonic (dynamic constant external resistance [DCER]) muscle actions under various loads. Concentric DCER leg extension power outputs were assessed in 12 healthy male subjects after 2 types of pretreatment. The pretreatments included (a) static stretching treatment performing 6 types of static stretching on leg extensors (4 sets of 30 seconds each with 20-second rest periods; total duration 20 minutes) and (b) nonstretching treatment by resting for 20 minutes in a sitting position. Loads during assessment of the power output were set to 5, 30, and 60% of the maximum voluntary contractile (MVC) torque with isometric leg extension in each subject. The peak power output following the static stretching treatment was significantly (p < 0.05) lower than that following the nonstretching treatment under each load (5% MVC, 418.0 +/- 82.2 W vs. 466.2 +/- 89.5 W; 30% MVC, 506.4 +/- 82.8 W vs. 536.4 +/- 97.0 W; 60% MVC, 478.6 +/- 77.5 W vs. 523.8 +/- 97.8 W). The present study demonstrated that relatively extensive static stretching significantly reduces power output with concentric DCER muscle actions under various loads. Common power activities are carried out by DCER muscle actions under various loads. Therefore, the result of the present study suggests that relatively extensive static stretching decreases power performance.

  9. High-Power Piezoelectric Acoustic-Electric Power Feedthru for Metal Walls

    NASA Technical Reports Server (NTRS)

    Bao, Xiaoqi; Biederman, Will; Sherrit, Stewart; Badescu, Mircea; Bar-Cohen, Yoseph; Jones, Christopher; Aldrich, Jack; Chang, Zensheu

    2008-01-01

    Piezoelectric acoustic-electric power feed-through devices transfer electric power wirelessly through a solid wall by using acoustic waves. This approach allows for the removal of holes through structures. The technology is applicable to power supply for electric equipment inside sealed containers, vacuum or pressure vessels, etc where the holes on the wall are prohibitive or result in significant performance degrade or complex designs. In the author's previous work, 100-W electric power was transferred through a metal wall by a small, simple-structure piezoelectric device. To meet requirements of higher power applications, the feasibility to transfer kilowatts level power was investigated. Pre-stressed longitudinal piezoelectric feedthru devices were analyzed by finite element model. An equivalent circuit model was developed to predict the power transfer characteristics to different electric loads. Based on the analysis results, a prototype device was designed, fabricated and a demonstration of the transmission of electric power up to 1-kW was successfully conducted. The methods to minimize the plate wave excitation on the wall were also analyzed. Both model analysis and experimental results are presented in detail in this presentation.

  10. Progress in Acoustic Transmission of Power through Walls

    NASA Technical Reports Server (NTRS)

    Sherrit,Stewart; Coty, Benjamin; Bao, Xiaoqi; Bar-Cohen, Yoseph; Badescu, Mircea; Chang, Zensheu

    2008-01-01

    A document presents updated information on implementation of the wireless acoustic-electric feed-through (WAEF) concept, which was reported in Using Piezoelectric Devices To Transmit Power Through Walls (NPO-41157), NASA Tech Briefs, Vol. 32, No. 6 (June 2008), page 70. To recapitulate: In a basic WAEF setup, a transmitting piezoelectric transducer on one side of a wall is driven at resonance to excite ultrasonic vibrations in the wall. A receiving piezoelectric transducer on the opposite side of the wall converts the vibrations back to an ultrasonic AC electric signal, which is then detected and otherwise processed in a manner that depends on the modulation (if any) applied to the signal and whether the signal is used to transmit power, data, or both. The present document expands upon the previous information concerning underlying physical principles, advantages, and potential applications of WAEF. It discusses the design and construction of breadboard prototype piezoelectric transducers for WAEF. It goes on to present results of computational simulations of performance and results of laboratory tests of the prototypes. In one notable test, a 100-W light bulb was lit by WAEF to demonstrate the feasibility of powering a realistic load.

  11. Optimal design parameters of the bicycle-rider system for maximal muscle power output.

    PubMed

    Yoshihuku, Y; Herzog, W

    1990-01-01

    The purpose of this study was to find the optimal values of design parameters for a bicycle-rider system (crank length, pelvic inclination, seat height, and rate of crank rotation) which maximize the power output from muscles of the human lower limb during bicycling. The human lower limb was modelled as a planar system of five rigid bodies connected by four smooth pin joints and driven by seven functional muscle groups. The muscles were assumed to behave according to an adapted form of Hill's equation. The dependence of the average power on the design parameters was examined. The instantaneous power of each muscle group was studied and simultaneous activity of two seemingly antagonistic muscle groups was analyzed. Average peak power for one full pedal revolution was found to be around 1100 W. The upper body position corresponding to this peak power output was slightly reclined, and the pedalling rate was 155 rpm for a nominal crank length of 170 mm.

  12. Output power characteristics and performance of TOPAZ II Thermionic Fuel Element No. 24

    SciTech Connect

    Luchau, D.W.; Bruns, D.R.; Izhvanov, O.; Androsov, V.

    1996-03-01

    A final report on the output power characteristics and capabilities of single cell TOPAZ II Thermionic Fuel Element (TFE) No. 24 is presented. Thermal power tests were conducted for over 3000 hours to investigate converter performance under normal and adverse operating conditions. Experiments conducted include low power testing, high power testing, air introduction to the interelectrode gap, collector temperature optimization, thermal modeling, and output power characteristic measurements. During testing, no unexpected degradation in converter performance was observed. The TFE has been removed from the test stand and returned to Scientific Industrial Association {open_quote}{open_quote}LUCH{close_quote}{close_quote} for materials analysis and report. This research was conducted at the Thermionic System Evaluation Test (TSET) Facility at the New Mexico Engineering Research Institute (NMERI) as a part of the Topaz International Program (TIP) by the Air Force Phillips Laboratory (PL). {copyright} {ital 1996 American Institute of Physics.}

  13. High-frequency resonant tunnelling diode oscillator with high-output power

    NASA Astrophysics Data System (ADS)

    Wang, Jue; Alharbi, Khalid; Ofiare, Afesomeh; Khalid, Ata; Cumming, David; Wasige, Edward

    2015-10-01

    In this paper, a prototype G-band (140 GHz-220 GHz) monolithic microwave integrated circuit (MMIC) resonant tunneling diode (RTD) oscillator is reported. The oscillator employs two In0.53Ga0.47As/AlAs RTD devices in the circuit to increase the output power. The measured output power was about 0.34 mW (-4.7 dBm) at 165.7 GHz, which is the highest power reported for RTD oscillator in G-band frequency range. This result demonstrates the validity of the high frequency/high power RTD oscillator design. It indicates that RTD devices, as one of the terahertz (THz) source candidates, have promising future for room-temperature THz applications in such as imaging, wireless communication and spectroscopy analysis, etc. By optimizing RTD oscillator design, it is expected that considerably higher power (>1 mW) at THz frequencies (>300 GHz) will be obtained.

  14. Universal efficiency bounds of weak-dissipative thermodynamic cycles at the maximum power output.

    PubMed

    Guo, Juncheng; Wang, Junyi; Wang, Yuan; Chen, Jincan

    2013-01-01

    Based on the assumption of weak dissipation introduced by Esposito et al. [Phys. Rev. Lett. 105, 150603 (2010)], analytic expressions for the efficiency bounds of several classes of typical thermodynamic cycles at the maximum power output are derived. The results obtained are of universal significance. They can be used to conveniently reveal the general characteristics of not only Carnot heat engines, but also isothermal chemical engines, non-Carnot heat engines, flux flow engines, gravitational engines, quantum Carnot heat engines, and two-level quantum Carnot engines at the maximum power output and to directly draw many important conclusions in the literature.

  15. A tunable erbium-doped fiber ring laser with power-equalized output

    NASA Astrophysics Data System (ADS)

    Yeh, Chien-Hung; Lin, Ming-Ching; Chi, Sien

    2006-12-01

    We propose and demonstrate a tunable erbium-based fiber ring laser with power-equalized output. When a mode-restricting intracavity fiber Fabry-Perot tunable filter (FFP-TF) is combined, the proposed resonator can guarantee a tunable laser oscillation. This proposed laser can obtain the flatter lasing wavelength in an effectively operating range of 1533.3 to 1574.6 nm without any other operating mechanism. Moreover, the performances of the output power, wavelength tuning range, and side-mode suppression ratio (SMSR) were studied.

  16. Smoothing Control of Wind Farm Output by Using Kinetic Energy of Variable Speed Wind Power Generators

    NASA Astrophysics Data System (ADS)

    Sato, Daiki; Saitoh, Hiroumi

    This paper proposes a new control method for reducing fluctuation of power system frequency through smoothing active power output of wind farm. The proposal is based on the modulation of rotaional kinetic energy of variable speed wind power generators through power converters between permanent magnet synchronous generators (PMSG) and transmission lines. In this paper, the proposed control is called Fluctuation Absorption by Flywheel Characteristics control (FAFC). The FAFC can be easily implemented by adding wind farm output signal to Maximum Power Point Tracking control signal through a feedback control loop. In order to verify the effectiveness of the FAFC control, a simulation study was carried out. In the study, it was assumed that the wind farm consisting of PMSG type wind power generator and induction machine type wind power generaotors is connected with a power sysem. The results of the study show that the FAFC control is a useful method for reducing the impacts of wind farm output fluctuation on system frequency without additional devices such as secondary battery.

  17. Improved thermoelectric power output from multilayered polyethylenimine doped carbon nanotube based organic composites

    SciTech Connect

    Hewitt, Corey A.; Montgomery, David S.; Barbalace, Ryan L.; Carlson, Rowland D.; Carroll, David L.

    2014-05-14

    By appropriately selecting the carbon nanotube type and n-type dopant for the conduction layers in a multilayered carbon nanotube composite, the total device thermoelectric power output can be increased significantly. The particular materials chosen in this study were raw single walled carbon nanotubes for the p-type layers and polyethylenimine doped single walled carbon nanotubes for the n-type layers. The combination of these two conduction layers leads to a single thermocouple Seebeck coefficient of 96 ± 4 μVK{sup −1}, which is 6.3 times higher than that previously reported. This improved Seebeck coefficient leads to a total power output of 14.7 nW per thermocouple at the maximum temperature difference of 50 K, which is 44 times the power output per thermocouple for the previously reported results. Ultimately, these thermoelectric power output improvements help to increase the potential use of these lightweight, flexible, and durable organic multilayered carbon nanotube based thermoelectric modules in low powered electronics applications, where waste heat is available.

  18. Improved thermoelectric power output from multilayered polyethylenimine doped carbon nanotube based organic composites

    NASA Astrophysics Data System (ADS)

    Hewitt, Corey A.; Montgomery, David S.; Barbalace, Ryan L.; Carlson, Rowland D.; Carroll, David L.

    2014-05-01

    By appropriately selecting the carbon nanotube type and n-type dopant for the conduction layers in a multilayered carbon nanotube composite, the total device thermoelectric power output can be increased significantly. The particular materials chosen in this study were raw single walled carbon nanotubes for the p-type layers and polyethylenimine doped single walled carbon nanotubes for the n-type layers. The combination of these two conduction layers leads to a single thermocouple Seebeck coefficient of 96 ± 4 μVK-1, which is 6.3 times higher than that previously reported. This improved Seebeck coefficient leads to a total power output of 14.7 nW per thermocouple at the maximum temperature difference of 50 K, which is 44 times the power output per thermocouple for the previously reported results. Ultimately, these thermoelectric power output improvements help to increase the potential use of these lightweight, flexible, and durable organic multilayered carbon nanotube based thermoelectric modules in low powered electronics applications, where waste heat is available.

  19. Somatotype-variables related to muscle torque and power output in female volleyball players.

    PubMed

    Buśko, Krzysztof; Lewandowska, Joanna; Lipińska, Monika; Michalski, Radosław; Pastuszak, Anna

    2013-01-01

    The purpose of this study was to investigate the relationship between somatotype, muscle torque, maximal power output and height of rise of the body mass centre measured in akimbo counter movement jump (ACMJ), counter movement jump (CMJ) and spike jump (SPJ), and power output measured in maximal cycle ergometer exercise bouts in female volleyball players. Fourteen players participated in the study. Somatotype was determined using the Heath-Carter method. Maximal muscle torque was measured under static conditions. Power output was measured in 5 maximal cycle ergometer exercise bouts, 10 s each, at increasing external loads equal to 2.5, 5.0, 7.5, 10.0 and 12.5% of body weight (BW). All jump trials (ACMJ, SPJ and CMJ) were performed on a force plate. The mean somatotype of volleyball players was: 4.9-3.5-2.5. The value of the sum of muscle torque of the left upper extremities was significantly correlated only with mesomorphic component. Mesomorphic and ectomorphic components correlated significantly with values of maximal power measured during ACMJ and CMJ. Power output measured in maximal cycle ergometer exercise bouts at increasing external loads equal to 2.5, 5.0 and 7.5% of BW was significantly correlated with endomorphy, mesomorphy and ectomorphy. PMID:23952250

  20. Somatotype-variables related to muscle torque and power output in female volleyball players.

    PubMed

    Buśko, Krzysztof; Lewandowska, Joanna; Lipińska, Monika; Michalski, Radosław; Pastuszak, Anna

    2013-01-01

    The purpose of this study was to investigate the relationship between somatotype, muscle torque, maximal power output and height of rise of the body mass centre measured in akimbo counter movement jump (ACMJ), counter movement jump (CMJ) and spike jump (SPJ), and power output measured in maximal cycle ergometer exercise bouts in female volleyball players. Fourteen players participated in the study. Somatotype was determined using the Heath-Carter method. Maximal muscle torque was measured under static conditions. Power output was measured in 5 maximal cycle ergometer exercise bouts, 10 s each, at increasing external loads equal to 2.5, 5.0, 7.5, 10.0 and 12.5% of body weight (BW). All jump trials (ACMJ, SPJ and CMJ) were performed on a force plate. The mean somatotype of volleyball players was: 4.9-3.5-2.5. The value of the sum of muscle torque of the left upper extremities was significantly correlated only with mesomorphic component. Mesomorphic and ectomorphic components correlated significantly with values of maximal power measured during ACMJ and CMJ. Power output measured in maximal cycle ergometer exercise bouts at increasing external loads equal to 2.5, 5.0 and 7.5% of BW was significantly correlated with endomorphy, mesomorphy and ectomorphy.

  1. Scalable and enhanced triboelectric output power generation by surface functionalized nanoimprint patterns

    NASA Astrophysics Data System (ADS)

    Hyeog Kwon, Yang; Shin, Sung-Ho; Jung, Joo-Yun; Nah, Junghyo

    2016-05-01

    We report nanoimprint lithographic submicron surface patterning for scalable output power generation and performance enhancement in triboelectric nanogenerators (TENGs). Specifically, one contact surface of a TENG is nanoimprinted with polyurethane acrylate (PUA) lines in different pitches and the counter contact surface is coated with perfluoropolyether (PFPE). The results show that a TENG with 200 nm pitch PUA lines exhibits voltage and current up to ˜430 V and ˜55 μA cm-2, generating about a sixfold higher output power than that with a flat PUA surface at an applied force of 0.3 MPa. In addition, scalable output power was obtained by adjusting line pitches. Further enhancement in output power was also demonstrated by chemically functionalizing the PUA line patterns with poly (diallyldimethylammonium chloride) (PDDA). The PDDA functionalization boosted voltage and current up to ˜500 V and ˜100 μA cm-2, respectively, which corresponds to ˜50% power density enhancement. The approach introduced here is a simple, effective, scalable and reproducible way to fabricate TENGs.

  2. Output power stability of a HCN laser using a stepping motor for the EAST interferometer system

    NASA Astrophysics Data System (ADS)

    Zhang, J. B.; Wei, X. C.; Liu, H. Q.; Shen, J. J.; Zeng, L.; Jie, Y. X.

    2015-11-01

    The HCN laser on EAST is a continuous wave glow discharge laser with 3.4 m cavity length and 120 mW power output at 337 μ m wavelength. Without a temperature-controlled system, the cavity length of the laser is very sensitive to the environmental temperature. An external power feedback control system is applied on the HCN laser to stabilize the laser output power. The feedback system is composed of a stepping motor, a PLC, a supervisory computer, and the corresponding control program. One step distance of the stepping motor is 1 μ m and the time response is 0.5 s. Based on the power feedback control system, a stable discharge for the HCN laser is obtained more than eight hours, which satisfies the EAST experiment.

  3. Output Power Control of Wind Turbine Generator by Pitch Angle Control using Minimum Variance Control

    NASA Astrophysics Data System (ADS)

    Senjyu, Tomonobu; Sakamoto, Ryosei; Urasaki, Naomitsu; Higa, Hiroki; Uezato, Katsumi; Funabashi, Toshihisa

    In recent years, there have been problems such as exhaustion of fossil fuels, e. g., coal and oil, and environmental pollution resulting from consumption. Effective utilization of renewable energies such as wind energy is expected instead of the fossil fuel. Wind energy is not constant and windmill output is proportional to the cube of wind speed, which cause the generated power of wind turbine generators (WTGs) to fluctuate. In order to reduce fluctuating components, there is a method to control pitch angle of blades of the windmill. In this paper, output power leveling of wind turbine generator by pitch angle control using an adaptive control is proposed. A self-tuning regulator is used in adaptive control. The control input is determined by the minimum variance control. It is possible to compensate control input to alleviate generating power fluctuation with using proposed controller. The simulation results with using actual detailed model for wind power system show effectiveness of the proposed controller.

  4. Variable gas spring for matching power output from FPSE to load of refrigerant compressor

    DOEpatents

    Chen, Gong; Beale, William T.

    1990-01-01

    The power output of a free piston Stirling engine is matched to a gas compressor which it drives and its stroke amplitude is made relatively constant as a function of power by connecting a gas spring to the drive linkage from the engine to the compressor. The gas spring is connected to the compressor through a passageway in which a valve is interposed. The valve is linked to the drive linkage so it is opened when the stroke amplitude exceeds a selected limit. This allows compressed gas to enter the spring, increase its spring constant, thus opposing stroke increase and reducing the phase lead of the displacer ahead of the piston to reduce power output and match it to a reduced load power demand.

  5. Variable gas spring for matching power output from FPSE to load of refrigerant compressor

    DOEpatents

    Chen, G.; Beale, W.T.

    1990-04-03

    The power output of a free piston Stirling engine is matched to a gas compressor which it drives and its stroke amplitude is made relatively constant as a function of power by connecting a gas spring to the drive linkage from the engine to the compressor. The gas spring is connected to the compressor through a passageway in which a valve is interposed. The valve is linked to the drive linkage so it is opened when the stroke amplitude exceeds a selected limit. This allows compressed gas to enter the spring, increase its spring constant, thus opposing stroke increase and reducing the phase lead of the displacer ahead of the piston to reduce power output and match it to a reduced load power demand. 6 figs.

  6. Robust cooperative output tracking of networked high-order power integrators systems

    NASA Astrophysics Data System (ADS)

    Peng, J. M.; Wang, J. N.; Shan, J. Y.

    2016-02-01

    This paper focuses on a robust cooperative output tracking problem of networked power integrator systems. The dynamics of each system is considered as a nonlinear high-order power integrator whose linearised model is uncontrollable around its origin. It is proven via Lyapunov Theory that under some mild assumptions and graph structural properties, all agents' outputs in the network can be synchronised to a desired trajectory with a bounded error in the presence of external disturbances as well as model uncertainties. Moreover, the tracking performance can be tuned by appropriately choosing parameters within the controller. The proposed controller for each agent is in the essence constructed via backstepping technique consisting of three components: the state feedback of its own, the outputs of its neighbours and the information of the desired trajectory if connected, and thus in a distributed manner.

  7. Power Output and Air Requirements of a Two-stroke Cycle Engine for Aeronautical Use

    NASA Technical Reports Server (NTRS)

    Paton, C R; Kemper, Carlton

    1927-01-01

    This investigation was undertaken to determine the pressure and amount of air necessary for satisfactory high-speed, two-stroke cycle operation and thus permit the power requirements of the air pump or blower to be determined. Based on power output and air requirement here obtained the two-stroke cycle engine would seem to be favorable for aeronautical use. No attempts were made to secure satisfactory operation at idling speeds.

  8. Power Quality Improvement in Bridgeless Ac-Dc Converter Based Multi-output Switched Mode Power Supply

    NASA Astrophysics Data System (ADS)

    Singh, Shihka; Singh, Bhim; Bhuvaneswari, G.; Bist, Vashist

    2014-12-01

    Computer power supplies are required to have multiple isolated regulated dc voltages with low ripple content and high input power factor at the utility interface. A dc-dc converter is used for obtaining these isolated multi-output dc voltages with excellent regulation. In this paper, a non-isolated ac-dc converter is proposed as the first stage converter to obtain a regulated dc output rather than using a simple uncontrolled diode bridge rectifier at the front end. A dc-dc converter is used at the second stage that has a high frequency transformer with multiple secondary windings to obtain different dc voltage levels at the output. The proposed bridgeless converter based power supply is designed using fundamental design equations, and different component values are calculated. Extensive simulations are carried out to demonstrate the improved performance of the proposed bridgeless converter based multi-output computer power supply at varying source voltages and load conditions. Experimental validation of the power supply is carried on a developed hardware prototype, and the test results are compared with the simulated performance for design verification.

  9. Maximizing Output Power in a Cantilevered Piezoelectric Vibration Energy Harvester by Electrode Design

    NASA Astrophysics Data System (ADS)

    Du, Sijun; Jia, Yu; Seshia, Ashwin

    2015-12-01

    A resonant vibration energy harvester typically comprises of a clamped anchor and a vibrating shuttle with a proof mass. Piezoelectric materials are embedded in locations of high strain in order to transduce mechanical deformation into electric charge. Conventional design for piezoelectric vibration energy harvesters (PVEH) usually utilizes piezoelectric material and metal electrode layers covering the entire surface area of the cantilever with no consideration provided to examining the trade-off involved with respect to maximizing output power. This paper reports on the theory and experimental verification underpinning optimization of the active electrode area of a cantilevered PVEH in order to maximize output power. The analytical formulation utilizes Euler-Bernoulli beam theory to model the mechanical response of the cantilever. The expression for output power is reduced to a fifth order polynomial expression as a function of the electrode area. The maximum output power corresponds to the case when 44% area of the cantilever is covered by electrode metal. Experimental results are also provided to verify the theory.

  10. Bicycle pedalling forces as a function of pedalling rate and power output.

    PubMed

    Patterson, R P; Moreno, M I

    1990-08-01

    Eleven men with recreational bicycling experience rode a bicycle ergometer with instrumented force pedals to determine the effects of pedalling rate and power output on the total resultant pedal force, Fr, and the component of the force perpendicular to the crank arm. The force patterns were obtained at power outputs of 100 W and 200 W for pedalling rates of 40-120 rpm in intervals of 10 rpm. Data were not obtained at 40 rpm at the 200 W power output. The Fr averaged over a crank cycle (Far) was lowest at 90 rpm and 100 W, a value statically different (P less than 0.05) from those at 40, 50, and 120 rpm. At 200 W, the Fr was lowest at 100 rpm, a value statistically different (P less than 0.05) from those at 50, 60, and 70 rpm. The Far varied widely (range of 30% of mean for all subjects) for individuals at a given power output. The results suggest that pedalling at 90-100 rpm may minimize peripheral forces and therefore peripheral muscle fatigue even though this rate may result in higher oxygen uptake.

  11. Acoustic agglomeration of power plant fly ash. Final report

    SciTech Connect

    Reethof, G.; McDaniel, O.H.

    1982-01-01

    The work has shown that acoustic agglomeration at practical acoustic intensities and frequencies is technically and most likely economically viable. The following studies were performed with the listed results: The physics of acoustic agglomeration is complex particularly at the needed high acoustic intensities in the range of 150 to 160 dB and frequencies in the 2500 Hz range. The analytical model which we developed, although not including nonlinear acoustic efforts, agreed with the trends observed. We concentrated our efforts on clarifying the impact of high acoustic intensities on the generation of turbulence. Results from a special set of tests show that although some acoustically generated turbulence of sorts exists in the 150 to 170 dB range with acoustic streaming present, such turbulence will not be a significant factor in acoustic agglomeration compared to the dominant effect of the acoustic velocities at the fundamental frequency and its harmonics. Studies of the robustness of the agglomerated particles using the Anderson Mark III impactor as the source of the shear stresses on the particles show that the agglomerates should be able to withstand the rigors of flow through commercial cyclones without significant break-up. We designed and developed a 700/sup 0/F tubular agglomerator of 8'' internal diameter. The electrically heated system functioned well and provided very encouraging agglomeration results at acoustic levels in the 150 to 160 dB and 2000 to 3000 Hz ranges. We confirmed earlier results that an optimum frequency exists at about 2500 Hz and that larger dust loadings will give better results. Studies of the absorption of acoustic energy by various common gases as a function of temperature and humidity showed the need to pursue such an investigation for flue gas constituents in order to provide necessary data for the design of agglomerators. 65 references, 56 figures, 4 tables.

  12. Electrospun ion gel nanofibers for flexible triboelectric nanogenerator: electrochemical effect on output power

    NASA Astrophysics Data System (ADS)

    Ye, Byeong Uk; Kim, Byoung-Joon; Ryu, Jungho; Lee, Joo Yul; Baik, Jeong Min; Hong, Kihyon

    2015-10-01

    A simple fabrication route for ion gel nanofibers in a triboelectric nanogenerator was demonstrated. Using an electrospinning technique, we could fabricate a large-area ion gel nanofiber mat. The triboelectric nanogenerator was demonstrated by employing an ion gel nanofiber and the device exhibited an output power of 0.37 mW and good stability under continuous operation.A simple fabrication route for ion gel nanofibers in a triboelectric nanogenerator was demonstrated. Using an electrospinning technique, we could fabricate a large-area ion gel nanofiber mat. The triboelectric nanogenerator was demonstrated by employing an ion gel nanofiber and the device exhibited an output power of 0.37 mW and good stability under continuous operation. Electronic supplementary information (ESI) available: I. Experimental section. II. FTIR and XRD spectra of ion gel nanofiber. III. Output voltage of TENG with various polymer nanofibers. IV. Output voltage of TENG under different connection types. V. Output voltage of TENG with 20 wt% ion gel nanofibers. See DOI: 10.1039/c5nr02602d

  13. Power-Combined GaN Amplifier with 2.28-W Output Power at 87 GHz

    NASA Technical Reports Server (NTRS)

    Fung, King Man; Ward, John; Chattopadhyay, Goutam; Lin, Robert H.; Samoska, Lorene A.; Kangaslahti, Pekka P.; Mehdi, Imran; Lambrigtsen, Bjorn H.; Goldsmith, Paul F.; Soria, Mary M.; Cooperrider, Joelle T.; Bruneau, Peter J.; Kurdoghlian, Ara; Micovic, Miroslav

    2011-01-01

    Future remote sensing instruments will require focal plane spectrometer arrays with higher resolution at high frequencies. One of the major components of spectrometers are the local oscillator (LO) signal sources that are used to drive mixers to down-convert received radio-frequency (RF) signals to intermediate frequencies (IFs) for analysis. By advancing LO technology through increasing output power and efficiency, and reducing component size, these advances will improve performance and simplify architecture of spectrometer array systems. W-band power amplifiers (PAs) are an essential element of current frequency-multiplied submillimeter-wave LO signal sources. This work utilizes GaN monolithic millimeter-wave integrated circuit (MMIC) PAs developed from a new HRL Laboratories LLC 0.15- m gate length GaN semiconductor transistor. By additionally waveguide power combining PA MMIC modules, the researchers here target the highest output power performance and efficiency in the smallest volume achievable for W-band.

  14. Human power output during repeated sprint cycle exercise: the influence of thermal stress.

    PubMed

    Ball, D; Burrows, C; Sargeant, A J

    1999-03-01

    Thermal stress is known to impair endurance capacity during moderate prolonged exercise. However, there is relatively little available information concerning the effects of thermal stress on the performance of high-intensity short-duration exercise. The present experiment examined human power output during repeated bouts of short-term maximal exercise. On two separate occasions, seven healthy males performed two 30-s bouts of sprint exercise (sprints I and II), with 4 min of passive recovery in between, on a cycle ergometer. The sprints were performed in both a normal environment [18.7 (1.5) degrees C, 40 (7)% relative humidity (RH; mean SD)] and a hot environment [30.1 (0.5) degrees C, 55 (9)% RH]. The order of exercise trials was randomised and separated by a minimum of 4 days. Mean power, peak power and decline in power output were calculated from the flywheel velocity after correction for flywheel acceleration. Peak power output was higher when exercise was performed in the heat compared to the normal environment in both sprint I [910 (172) W vs 656 (58) W; P < 0.01] and sprint II [907 (150) vs 646 (37) W; P < 0.05]. Mean power output was higher in the heat compared to the normal environment in both sprint I [634 (91) W vs 510 (59) W; P < 0.05] and sprint II [589 (70) W vs 482 (47) W; P < 0.05]. There was a faster rate of fatigue (P < 0.05) when exercise was performed in the heat compared to the normal environment. Arterialised-venous blood samples were taken for the determination of acid-base status and blood lactate and blood glucose before exercise, 2 min after sprint I, and at several time points after sprint II. Before exercise there was no difference in resting acid-base status or blood metabolites between environmental conditions. There was a decrease in blood pH, plasma bicarbonate and base excess after sprint I and after sprint II. The degree of post-exercise acidosis was similar when exercise was performed in either of the environmental conditions

  15. Quantum cascade laser master-oscillator power-amplifier with 1.5 W output power at 300 K.

    PubMed

    Menzel, Stefan; Diehl, Laurent; Pflügl, Christian; Goyal, Anish; Wang, Christine; Sanchez, Antonio; Turner, George; Capasso, Federico

    2011-08-15

    We report quantum cascade laser (QCL) master-oscillator power-amplifiers (MOPAs) at 300 K reaching output power of 1.5 W for tapered devices and 0.9 W for untapered devices. The devices display single-longitudinal-mode emission at λ = 7.26 µm and single-transverse-mode emission at TM(00). The maximum amplification factor is 12 dB for the tapered devices. PMID:21934985

  16. Target spectrum matrix definition for multiple-input- multiple-output control strategies applied on direct-field- acoustic-excitation tests

    NASA Astrophysics Data System (ADS)

    Alvarez Blanco, M.; Janssens, K.; Bianciardi, F.

    2016-09-01

    During the last two decades there have been several improvements on environmental acoustic qualification testing for launch and space vehicles. Direct field excitation (DFAX) tests using Multiple-Input-Multiple-Output (MIMO) control strategies seems to become the most cost-efficient way for component and subsystem acoustic testing. However there are still some concerns about the uniformity and diffusivity of the acoustic field produced by direct field testing. Lately, much of the documented progresses aimed to solve the non-uniformity of the field by altering the sound pressure level requirement, limiting responses and adding or modifying control microphones positions. However, the first two solutions imply modifying the qualification criteria, which could lead to under-testing, potentially risking the mission. Furthermore, adding or moving control microphones prematurely changes the system configuration, even if it is an optimal geometric layout in terms of wave interference patterns control. This research investigates the target definition as an initial condition for the acoustic MIMO control. Through experiments it is shown that for a given system configuration the performance of a DFAX test strongly depends on the target definition procedure. As output of this research a set of descriptors are presented describing a phenomenon defined as “Energy- sink”.

  17. Output power enhancement from ZnO nanorods piezoelectric nanogenerators by Si microhole arrays.

    PubMed

    Baek, Seong-Ho; Hasan, Md Roqibul; Park, Il-Kyu

    2016-02-12

    We demonstrate the enhancement of output power from a ZnO nanorod (NR)-based piezoelectric nanogenerator by using Si microhole (Si-μH) arrays. The depth-controlled Si-μH arrays were fabricated by using the deep reactive ion etching method. The ZnO NRs were grown along the Si-μH surface, in holes deeper than 20 μm. The polymer layer, polydimethylsiloxane, which acts a stress diffuser and electrical insulator, was successfully penetrated into the deep Si-μH arrays. Optical investigations show that the crystalline quality of the ZnO NRs on the Si-μH arrays was not degraded, even though they were grown on the deeper Si-μH arrays. As the depth of the Si-μH arrays increase from 0 to 20 μm, the output voltage was enhanced by around 8.1 times while the current did not increase. Finally, an output power enhancement of ten times was obtained. This enhancement of the output power was consistent with the increase in the surface area, and was mainly attributed to the accumulation of the potentials generated by the series-connected ZnO NR-based nanogenerators, whose number increases as the depth of the Si-μH increases.

  18. Validation of a six second cycle test for the determination of peak power output.

    PubMed

    Herbert, Peter; Sculthorpe, Nick; Baker, Julien S; Grace, Fergal M

    2015-01-01

    The present study examined the agreement between peak power output during a standard Wingate anaerobic test (WAnT) and a six second 'all-out' test on a Wattbike Pro. Nine males (40.7 ± 19.4 yrs, 1.76 ± 0.03 cm, 82.11 ± 8.9 kg) underwent three testing protocols on separate days. The protocols consisted 30 second WAnT (WAnT30), a modified WAnT over 6 seconds (WAnT6) and a 6 second peak power test (PPT6). PPT6 was correlated with WAnT30 (r = 0.9; p < 0.001) with a mean bias of 105 W. PPT6 correlated with WAnT6 (r = 0.95; p < 0.001) with a mean bias of 74 W. WAnT6 correlated with WAnT30 (r = 0.99; p < 0.001) with a mean bias of 31 W. There was no difference in time to peak power between any trial. PPT6 resulted in significantly greater power outputs than in WAnT30 and WAnT6 (p < 0.001). We conclude that PPT6 and WAnT6 are valid measures of peak power output compared with WAnT30. This identifies that PPT6 and WAnT6 as short duration 'all-out' tests that have practical applications for researchers and coaches who wish to assess peak power output without the fatiguing effects associated with a standard WAnT.

  19. High efficiency Tm:YAG slab laser with hundred-watts-level output power.

    PubMed

    Liu, Pian; Jin, Lin; Liu, Xuan; Huang, Haitao; Shen, Deyuan

    2016-04-01

    We report on a hundred-watts-level high power Tm:YAG slab laser system operating at room temperature. The laser has a threshold pump power of 46.7 W, benefiting from the good mode matching of an end-pumping scheme and the excellent heat-dissipation capability of our cooling system. At 350 W of incident pump power, 100 W of output power at ∼2015  nm has been generated, corresponding to a slope efficiency of 33.6% with respect to the incident pump power and an optical-to-optical conversion efficiency of 28.6%. As far as we know, this is the highest optical-to-optical conversion efficiency so far achieved in a high power Tm:YAG laser system operating at a hundred-watts level. PMID:27139649

  20. Wind tunnel study of the power output spectrum in a micro wind farm

    NASA Astrophysics Data System (ADS)

    Bossuyt, Juliaan; Howland, Michael F.; Meneveau, Charles; Meyers, Johan

    2016-09-01

    Instrumented small-scale porous disk models are used to study the spectrum of a surrogate for the power output in a micro wind farm with 100 models of wind turbines. The power spectra of individual porous disk models in the first row of the wind farm show the expected -5/3 power law at higher frequencies. Downstream models measure an increased variance due to wake effects. Conversely, the power spectrum of the sum of the power over the entire wind farm shows a peak at the turbine-to-turbine travel frequency between the model turbines, and a near -5/3 power law region at a much wider range of lower frequencies, confirming previous LES results. Comparison with the spectrum that would result when assuming that the signals are uncorrelated, highlights the strong effects of correlations and anti-correlations in the fluctuations at various frequencies.

  1. Ka-Band Waveguide Hybrid Combiner for MMIC Amplifiers With Unequal and Arbitrary Power Output Ratio

    NASA Technical Reports Server (NTRS)

    Simons, Rainee N.; Chevalier, Christine T.; Wintucky, Edwin G.; Freeman, Jon C.

    2009-01-01

    The design, simulation and characterization of a novel Ka-band (32.05 +/- 0.25 GHz) rectangular waveguide branch-line hybrid unequal power combiner is presented. The manufactured combiner was designed to combine input signals, which are in phase and with an amplitude ratio of two. The measured return loss and isolation of the branch-line hybrid are better than 22 and 27 dB, respectively. The application of the branch-line hybrid for combining two MMIC power amplifiers with output power ratio of two is demonstrated. The measured combining efficiency is approximately 93 percent over the above frequency band.

  2. Ka-Band Waveguide Hybrid Combiner for MMIC Amplifiers with Unequal and Arbitrary Power Output Ratio

    NASA Technical Reports Server (NTRS)

    Simons, Rainee N.; Chevalier, Christine T.; Wintucky, Edwin G.; Freeman, Jon C.

    2009-01-01

    The design, simulation and characterization of a novel Ka-band (32.05 +/- 0.25 GHz) rectangular waveguide branchline hybrid unequal power combiner is presented. The manufactured combiner was designed to combine input signals, which are nearly in phase and with an amplitude ratio of two. The measured return loss and isolation of the branch-line hybrid are better than 22 and 27 dB, respectively. The application of the branch-line hybrid for combining two monolithic microwave integrated circuit (MMIC) power amplifiers with output power ratio of two is demonstrated. The measured combining efficiency is 92.9% at the center frequency of 32.05 GHz.

  3. Mobility power flow analysis of coupled plate structure subjected to mechanical and acoustic excitation

    NASA Technical Reports Server (NTRS)

    Cuschieri, J. M.

    1992-01-01

    The mobility power flow approach that was previously applied in the derivation of expressions for the vibrational power flow between coupled plate substructures forming an L configuration and subjected to mechanical loading is generalized. Using the generalized expressions, both point and distributed mechanical loads on one or both of the plates can be considered. The generalized approach is extended to deal with acoustic excitation of one of the plate substructures. In this case, the forces (acoustic pressures) acting on the structure are dependent on the response of the structure because of the scattered pressure component. The interaction between the plate structure and the acoustic fluid leads to the derivation of a corrected mode shape for the plates' normal surface velocity and also for the structure mobility functions. The determination of the scattered pressure components in the expressions for the power flow represents an additional component in the power flow balance for the source plate and the receiver plate. This component represents the radiated acoustical power from the plate structure. For a number of coupled plate substrates, the acoustic pressure generated by one substructure will interact with the motion of another substructure. That is, in the case of the L-shaped plate, acoustic interaction exists between the two plate substructures due to the generation of the acoustic waves by each of the substructures. An approach to deal with this phenomena is described.

  4. Effect of oral creatine supplementation on power output and fatigue during bicycle ergometry.

    PubMed

    Cooke, W H; Grandjean, P W; Barnes, W S

    1995-02-01

    Our purpose was to determine the effect of oral creatine supplementation on exercise performance during high-intensity short-duration bicycle sprinting. Power output was recorded for 12 healthy untrained males (age 24.08 +/- 0.53 yr, weight 81.22 +/- 1.32 kg) before and after 5 days of creatine (n = 6) or placebo (n = 6) supplementation. A double-blind research design was employed. Subjects performed maximal sprints against a constant load (111.8 N) for 15 s. Each one-half pedal revolution was magnetically counted, and subsequent measurements of peak power, time to peak power, total work, and the fatigue index were digitized and stored on disk. Mean values for peak power, time to peak power, total work, and fatigue index were 958.01 +/- 40.66 W, 4.09 +/- 0.82 s, 11.28 +/- 0.46 kJ, and 32.1 +/- 1.58% decline from peak power, respectively. No significant differences were observed within or between groups before or after supplementation for any of the mechanical parameters measured (P > 0.05). These findings suggest that oral creatine supplementation does not positively affect power output or fatigue during continuous high-intensity bicycle exercise in untrained men.

  5. Incorrect calculation of power outputs masks the ergogenic capacity of creatine supplementation.

    PubMed

    Havenetidis, Konstadinos; Cooke, Carlton B; Butterly, Ron; King, Roderick F G J

    2006-10-01

    This study assessed the effect of incorrect calculation of power output measurement on the ergogenic properties of creatine. Fifteen males performed repeated Wingate anaerobic tests, under baseline, placebo, and creatine conditions. Statistics showed significant differences (p < 0.05) following creatine-supplemented conditions compared with placebo conditions, whereas no significant differences existed between the baseline and placebo conditions. However, the performance enhancement effect of creatine became significant only when the corrected (for the inertia of the flywheel) method was employed for measuring peak and minimum power. Mean (+/- SD) values across all cycle sprints for placebo versus creatine were 1033 +/- 100 W versus 1130 +/- 95 W for peak power and 385 +/- 78 W versus 427 +/- 70 W for minimum power. No significant differences were shown using the uncorrected method for peak power (756 +/- 97 W versus 786 +/- 88 W) and minimum power 440 +/- 64 W pre versus 452 +/- 65 W post). In conclusion, the present study suggests that the potentiating effect of creatine might be underestimated if the inertial effects of the flywheel are not considered in power output determination. PMID:17111019

  6. Low power, highly linear output buffer. [for infrared focal plane arrays

    NASA Technical Reports Server (NTRS)

    Foley, D.; Butler, N.; Stobie, J.

    1992-01-01

    A class AB CMOS output buffer has been designed for use on an IR focal plane array. Given the requirements for power dissipation and load capacitance a class A output, such as a source follower, would be unsuitable. The approach taken uses a class AB amplifier configured as a charge integrator. Thus it converts a charge packet in the focal plane multiplexer to a voltage which is then the output of the focal plane. With a quiescent current of 18 micro-a and a load capacitance of 100 pf, the amplifier has an open loop unity gain bandwidth of 900 khz. Integral nonlinearity is better than .03 percent over 5.5 volts when run with VDD-VSS = 6v.

  7. On the power output of some idealized source configurations with one or more characteristic dimensions

    NASA Technical Reports Server (NTRS)

    Levine, H.

    1982-01-01

    The calculation of power output from a (finite) linear array of equidistant point sources is investigated with allowance for a relative phase shift and particular focus on the circumstances of small/large individual source separation. A key role is played by the estimates found for a twin parameter definite integral that involves the Fejer kernel functions, where N denotes a (positive) integer; these results also permit a quantitative accounting of energy partition between the principal and secondary lobes of the array pattern. Continuously distributed sources along a finite line segment or an open ended circular cylindrical shell are considered, and estimates for the relatively lower output in the latter configuration are made explicit when the shell radius is small compared to the wave length. A systematic reduction of diverse integrals which characterize the energy output from specific line and strip sources is investigated.

  8. Simulation of one-minute power output from utility-scale photovoltaic generation systems.

    SciTech Connect

    Stein, Joshua S.; Ellis, Abraham; Hansen, Clifford W.

    2011-08-01

    We present an approach to simulate time-synchronized, one-minute power output from large photovoltaic (PV) generation plants in locations where only hourly irradiance estimates are available from satellite sources. The approach uses one-minute irradiance measurements from ground sensors in a climatically and geographically similar area. Irradiance is translated to power using the Sandia Array Performance Model. Power output is generated for 2007 in southern Nevada are being used for a Solar PV Grid Integration Study to estimate the integration costs associated with various utility-scale PV generation levels. Plant designs considered include both fixed-tilt thin-film, and single-axis-tracked polycrystalline Si systems ranging in size from 5 to 300 MW{sub AC}. Simulated power output profiles at one-minute intervals were generated for five scenarios defined by total PV capacity (149.5 MW, 222 WM, 292 MW, 492 MW, and 892 MW) each comprising as many as 10 geographically separated PV plants.

  9. Triple transit region photodiodes (TTR-PDs) providing high millimeter wave output power.

    PubMed

    Rymanov, Vitaly; Stöhr, Andreas; Dülme, Sebastian; Tekin, Tolga

    2014-04-01

    We report on a novel triple transit region (TTR) layer structure for 1.55 μm waveguide photodiodes (PDs) providing high output power in the millimeter wave (mmW) regime. Basically, the TTR-PD layer structure consists of three transit layers, in which electrons drift at saturation velocity or even at overshoot velocity. Sufficiently strong electric fields (>3000 V/cm) are achieved in all three transit layers even in the undepleted absorber layer and even at very high optical input power levels. This is achieved by incorporating three 10 nm thick p-doped electric field clamp layers. Numerical simulations using the drift-diffusion model (DDM) indicate that for optical intensities up to ~500 kW/cm(2), no saturation effects occur, i.e. the electric field exceeds the critical electric field in all three transit layers. This fact in conjunction with a high-frequency double-mushroom cross-section of the waveguide TTR-PD ensures high output power levels at mmW frequencies. Fabricated 1.55 µm InGaAs(P)/InP waveguide TTR-PDs exhibit output power levels exceeding 0 dBm (1 mW) and a return loss (RL) up to ~24 dB. Broadband operation with a 3 dB bandwidth beyond 110 GHz is achieved.

  10. Output power of a quantum dot laser: Effects of excited states

    SciTech Connect

    Wu, Yuchang; Jiang, Li Asryan, Levon V.

    2015-11-14

    A theory of operating characteristics of quantum dot (QD) lasers is discussed in the presence of excited states in QDs. We consider three possible situations for lasing: (i) ground-state lasing only; (ii) ground-state lasing at first and then the onset of also excited-state lasing with increasing injection current; (iii) excited-state lasing only. The following characteristics are studied: occupancies of the ground-state and excited-state in QDs, free carrier density in the optical confinement layer, threshold currents for ground- and excited-state lasing, densities of photons emitted via ground- and excited-state stimulated transitions, output power, internal and external differential quantum efficiencies. Under the conditions of ground-state lasing only, the output power saturates with injection current. Under the conditions of both ground- and excited-state lasing, the output power of ground-state lasing remains pinned above the excited-state lasing threshold while the power of excited-state lasing increases. There is a kink in the light-current curve at the excited-state lasing threshold. The case of excited-state lasing only is qualitatively similar to that for single-state QDs—the role of ground-state transitions is simply reduced to increasing the threshold current.

  11. Relationships between muscle power output using the stretch-shortening cycle and eccentric maximum strength.

    PubMed

    Miyaguchi, Kazuyoshi; Demura, Shinichi

    2008-11-01

    This study aimed to examine the relationships between muscle power output using the stretch-shortening cycle (SSC) and eccentric maximum strength under elbow flexion. Eighteen young adult males pulled up a constant light load (2 kg) by ballistic elbow flexion under the following two preliminary conditions: 1) the static relaxed muscle state (SR condition), and 2) using the SSC with countermovement (SSC condition).Muscle power was determined from the product of the pulling velocity and the load mass by a power measurement instrument that adopted the weight-loading method. We assumed the pulling velocity to be the subject's muscle power parameters as a matter of convenience, because we used a constant load. The following two parameters were selected in reference to a previous study: 1) peak velocity (m x s(-1)) (peak power) and 2) 0.1-second velocity during concentric contraction (m x s(-1)) (initial power). Eccentric maximum strength by elbow flexion was measured by a handheld dynamometer.Initial power produced in the SSC condition was significantly larger than that in the SR condition. Eccentric maximum strength showed a significant and high correlation (r = 0.70) with peak power in the SSC condition but not in the SR condition. Eccentric maximum strength showed insignificant correlations with initial power in both conditions. In conclusion, it was suggested that eccentric maximum strength is associated with peak power in the SSC condition, but the contribution of the eccentric maximum strength to the SSC potentiation (initial power) may be low.

  12. High-power piezoelectric acoustic-electric power feedthru for metal walls

    NASA Astrophysics Data System (ADS)

    Bao, Xiaoqi; Biederman, Will; Sherrit, Stewart; Badescu, Mircea; Bar-Cohen, Yoseph; Jones, Christopher; Aldrich, Jack; Chang, Zensheu

    2008-03-01

    Piezoelectric acoustic-electric power feed-through devices transfer electric power wirelessly through a solid wall using elastic waves. This approach allows for the elimination of the need for holes through structures for cabling or electrical feed-thrus . The technology supplies power to electric equipment inside sealed containers, vacuum or pressure vessels, etc where holes in the wall are prohibitive or may result in significant performance degradation or requires complex designs. In the our previous work, 100-W of electric power was transferred through a metal wall by a small, piezoelectric device with a simple-structure. To meet requirements of higher power applications, the feasibility to transfer kilowatts level power was investigated. Pre-stressed longitudinal piezoelectric feed-thru devices were analyzed by finite element modeling. An equivalent circuit model was developed to predict the characteristics of power transfer to different electric loads. Based on the analytical results, a prototype device was designed, fabricated and successfully demonstrated to transfer electric power at a level of 1-kW. Methods of minimizing plate wave excitation on the wall were also analyzed. Both model analysis and experimental results are presented in detail in this paper.

  13. Exploring the Power Output of Small Wind Turbines in Urban San Antonio, Texas

    NASA Astrophysics Data System (ADS)

    Casillas, Jose; Sperduti, Stephanie; Cardenas, Rosa

    2015-03-01

    The means of transporting power from a centralized power plant by transmission lines has several disadvantages. Electricity transmission and distribution networks are costly, require long planning processes and are unsightly to residents. These networks are also susceptible to natural disasters creating massive disruptions to consumers. For these reasons distributed power sources such as solar panels and small wind turbines are becoming a more desirable and viable means of energy production. We report on the status of a study to determine the maximum output power of small wind turbines in urban San Antonio, Texas. Wind speed data along with power measurements from small wind turbines in urban San Antonio will be reported. U.S. Department of Education Title V HSI-STEM and Articulation Award No. P031C110145.

  14. Measurement of output power density from mobile phone as a function of input sound frequency.

    PubMed

    Calabrò, Emanuele; Magazù, Salvatore

    2013-01-01

    Measurements of power density emitted by a mobile phone were carried out as a function of the sound frequency transmitted by a sound generator, ranging from 250 to 14000 Hz. Output power density was monitored by means of the selective radiation meter Narda SRM 3000 in spectrum analysis mode, and the octave frequency analysis of each tone used for the experimental design was acquired by the sound level meter Larson Davis LxT Wind. Vodafone providers were used for mobile phone calls with respect to various local base station in Southern-Italy. A relationship between the mobile phone microwaves power density and the sound frequencies transmitted by the sound generator was observed. In particular, microwaves power density level decreases significantly at sound frequency values larger than 4500 Hz. This result can be explained assuming that discontinuous transmission mode of global system for mobile communications is powered not only in silence-mode, but also at frequencies larger than 4500 Hz.

  15. Acoustic-loads research for powered-lift configurations

    NASA Technical Reports Server (NTRS)

    Schoenster, J. A.; Willis, C. M.; Schroeder, J. C.; Mixson, J. S.

    1976-01-01

    Data presented from large-scale model tests with jet engines having thrusts of 9 kN (2000 lb) and 36 kN (8000 lb) include acoustic loads for an externally blown wing and flap induced by a TF34 jet engine, an upper surface blown (USB) aircraft model in a wind tunnel, and two USB models in static tests. Comparisons of these results with results from acoustic loads studies on configurations of other sizes are made and the implications of these results on interior noise and acoustic fatigue are discussed.

  16. Power Output of Noise Sources Operating Near Elastic Scatterers of Finite Dimensions

    NASA Astrophysics Data System (ADS)

    TOMILINA, T. M.; BOBROVNITSKII, YU. I.; YASHKIN, V. B.; KOCHKIN, A. A.

    1999-09-01

    The problem of variation of the sound power output of noise sources due to reflecting boundaries and elastic scatterers is considered experimentally and numerically. In the laboratory experiment with a source of loudspeakers operating near a resonant scatterer, the increase in the radiated power obtained is about one hundred. An important role of the source near field in the power enhancement is shown. In computer simulation, a two-dimensional radiation problem for a circle vibrating near a finite elastic beam is studied. Most attention is paid to revealing physical mechanisms of the power output variations. It is shown that, for the source and elastic scatterer of finite dimensions, the radiated power can reach orders of magnitude of the free-field value. Especially, high-power amplification can be obtained at low frequencies for the sources that are poor radiators in free space, i.e., behave as multipoles of high order: presence of a scatterer or reflector makes such a source to be of monopole or dipole type. The results presented can be useful in better understanding sound generation mechanisms in complicated industrial noise sources.

  17. Simulation of the output power of copper bromide lasers by the MARS method

    SciTech Connect

    Iliev, I P; Voynikova, D S; Gocheva-Ilieva, S G

    2012-04-30

    The dependence of the output power of CuBr lasers (operating at wavelengths of 510.6 and 578.2 nm) on ten input physical parameters has been statistically analysed based on a large amount of experimental data accumulated for these lasers. Regression models have been built using the flexible nonparametric method of multivariate adaptive regression splines (MARS) to describe both linear and nonlinear local dependences. These models cover more than 97% initial data with an error comparable with the experimental error; they are applied to estimate and predict the output powers of both existing and future lasers. The advantage of the models constructed for estimating laser parameters over the standard parametric methods of multivariate factor and regression analysis is demonstrated.

  18. Suppression of beam induced pulse shortening modes in high power RF generator TW output structures

    SciTech Connect

    Haimson, J.; Mecklenburg, B.

    1992-12-31

    Several different style 11.4 GHz relativistic klystrons, operating with beam pulse widths of 50 ns and using large aperture, tapered phase-velocity TW structures,` have recently demonstrated output RF power levels in the range of 100 to 300 MW without breakdown or pulse shortening. To extend this performance into the long pulse regime (1 {mu}s) or to demonstrate a threefold increase in output power by using higher currents, the existing TW circuit designs must be modified (a) to reduce the cavity maximum surface E-fields by a factor of 2 to 3, and (b) to elevate the current threshold values of the beam induced higher order modes (HOM) to ensure avoidance of RF pulse shortening and associated instabilities. A technique for substantially elevating this threshold current is described, and microwave data and photographs are presented showing the degree of HOM damping achieved in a recently constructed 11.4 GHz TW structure.

  19. Constraints on muscular performance: trade-offs between power output and fatigue resistance.

    PubMed Central

    Wilson, Robbie S; James, Rob S

    2004-01-01

    An important functional and evolutionary constraint on the physical performance of vertebrates is believed to be the trade-off between speed and endurance capacity. However, despite the pervasiveness of physiological arguments, most studies have found no evidence of the trade-off when tested at the whole-animal level. We investigated the existence of this trade-off at the whole-muscle level, the presumed site of this physiological conflict, by examining inter-individual variation in both maximum power output and fatigue resistance for mouse extensor digitorum longus (EDL) muscle using the work-loop technique. We found negative correlations between several measures of in vitro maximum power output and force production with fatigue resistance for individual mouse EDL muscles, indicating functional trade-offs between these performance parameters. We suggest that this trade-off detected at the whole-muscle level has imposed an important constraint on the evolution of vertebrate physical performance. PMID:15252990

  20. Efficiency at maximum power output of linear irreversible Carnot-like heat engines.

    PubMed

    Wang, Yang; Tu, Z C

    2012-01-01

    The efficiency at maximum power output of linear irreversible Carnot-like heat engines is investigated based on the assumption that the rate of irreversible entropy production of the working substance in each "isothermal" process is a quadratic form of the heat exchange rate between the working substance and the reservoir. It is found that the maximum power output corresponds to minimizing the irreversible entropy production in two isothermal processes of the Carnot-like cycle, and that the efficiency at maximum power output has the form η(mP)=η(C)/(2-γη(C)), where η(C) is the Carnot efficiency, while γ depends on the heat transfer coefficients between the working substance and two reservoirs. The value of η(mP) is bounded between η(-)≡η(C)/2 and η(+)≡η(C)/(2-η(C)). These results are consistent with those obtained by Chen and Yan [J. Chem. Phys. 90, 3740 (1989)] based on the endoreversible assumption, those obtained by Esposito et al. [Phys. Rev. Lett. 105, 150603 (2010)] based on the low-dissipation assumption, and those obtained by Schmiedl and Seifert [Europhys. Lett. 81, 20003 (2008)] for stochastic heat engines which in fact also satisfy the low-dissipation assumption. Additionally, we find that the endoreversible assumption happens to hold for Carnot-like heat engines operating at the maximum power output based on our fundamental assumption, and that the Carnot-like heat engines that we focused on do not strictly satisfy the low-dissipation assumption, which implies that the low-dissipation assumption or our fundamental assumption is a sufficient but non-necessary condition for the validity of η(mP)=η(C)/(2-γη(C)) as well as the existence of two bounds, η(-)≡η(C)/2 and η(+)≡η(C)/(2-η(C)).

  1. Multifractal and local correlation of simultaneous wind speed-power output from a single wind trubine

    NASA Astrophysics Data System (ADS)

    Calif, Rudy; Schmitt, François G.; Huang, Yongxiang

    2014-05-01

    The wind energy production is a nonlinear and no stationary resource, due to the intermittent statistics of atmospheric wind speed at all spatial and temporal scales ranging from large scale variations to very short scale variations. Recently, Rudy et al.[1] observed the intermittent and multifractal properties of wind energy production. Classically, IEC standard 4100 is used by the wind energy community, for modeling the interactions of wind speed with the wind turbine. However, this model reflects gaussian statistics contrary to observed wind and energy production measurements. Modeling of power curve of a single wind turbine remains a challenge. The precise understanding of the dynamics of nonlinear power curve over very short time scales, is necessary. Hence, multifractal cross-correlation methods such as Generalized Correlations Exponents (GCE), multifractal detrended cross-correlation analysis (MFXDFA), multifractal detrending moving average cross-correlation analysis (MFXDMA) are applied to simultaneous wind speed power output from a single wind turbine to determine the nature of scaling correlation behavior. Furthermore, in order to detect eventual local correlation, an application of empirical mode decomposition based on time dependent intrinsic correlation to simultaneous measurements is performed. The simultaneous wind speed-power output measurements are recorded continuously with a sampling rate f = 1Hz, during 115 days in 2006. The wind speed measurements are obtained at 31 m above the ground, and the power output is delivered by 500 kW Nordtank wind turbine positionned at the Technical University, Risœ, Denmark. References [1] Calif, R., Schmitt, F.G., Huang, Y., Multifractal description of wind power fluctuations using arbitrary order Hilbert spectral analysis, Physica, 392, 4106-4120, 2013.

  2. Aggrandizing power output from Shewanella oneidensis MR-1 microbial fuel cells using calcium chloride.

    PubMed

    Fitzgerald, Lisa A; Petersen, Emily R; Gross, Benjamin J; Soto, Carissa M; Ringeisen, Bradley R; El-Naggar, Mohamed Y; Biffinger, Justin C

    2012-01-15

    There are several interconnected metabolic pathways in bacteria essential for the conversion of carbon electron sources directly into electrical currents using microbial fuel cells (MFCs). This study establishes a direct exogenous method to increase power output from a Shewanella oneidensis MR-1 containing MFC by adding calcium chloride to the culture medium. The current output from each CaCl(2) concentration tested revealed that the addition of CaCl(2) to 1400 μM increased the current density by >80% (0.95-1.76 μA/cm(2)) using sodium lactate as the sole carbon source. Furthermore, polarization curves showed that the maximum power output could be increased from 157 to 330 μW with the addition of 2080 μM CaCl(2). Since the conductivity of the culture medium did not change after the addition of CaCl(2) (confirmed by EIS and bulk conductivity measurements), this increase in power was primarily biological and not based on ionic effects. Thus, controlling the concentration of CaCl(2) is a pathway to increase the efficiency and performance of S. oneidensis MR-1 MFCs.

  3. Effect of parasitic plasma currents on solar-array power output

    NASA Technical Reports Server (NTRS)

    Domitz, S.; Kolecki, J. C.

    1979-01-01

    Solar-array voltage-current curves are calculated by assuming the existence of parasitic loads that consist of local currents of charged particles collected by the array. Three cases of interest are calculated to demonstrate how the distribution and magnitude of parasitic currents affect output. Solar array performance degradation became significant when the total parasitic current plus the load current exceeded the short-circuit current. Approximate graphical methods were useful for many applications. Power loss, which was calculated by summing the product of parasitic current and the local potential, underestimated the loss in maximum power.

  4. Output power characteristics of thin film-coated waveguide CO2 lasers

    NASA Astrophysics Data System (ADS)

    Miyagi, Mitsunobu; Wagatsuma, Yoshihiko; Nishida, Shigeo; Hongo, Akihito

    1987-02-01

    An output power efficiency of 9 percent is achieved in a germanium-coated brass waveguide CO2 laser at a gas pressure of 50 Torr and input RF power of 40 W. Pyrex glass is used as the insulator, and the germanium layer has a thickness of 0.5 micron. The direction of the polarization in the germanium coated brass-pyrex glass composite waveguide laser is found to be parallel to the metal plates. It is shown that the oscillating mode is the lowest-order mode, and that the profile can be approximately described by a Gaussian distribution when the noise level is properly subtracted.

  5. Integrated Tm:fiber MOPA with polarized output and narrow linewidth with 100 W average power.

    PubMed

    Shah, Lawrence; Sims, R Andrew; Kadwani, Pankaj; Willis, Christina C C; Bradford, Joshua B; Pung, Aaron; Poutous, Menelaos K; Johnson, Eric G; Richardson, Martin

    2012-08-27

    We report on a Tm:fiber master oscillator power amplifier (MOPA) system producing 109 W CW output power, with >15 dB polarization extinction ratio, sub-nm spectral linewidth, and M2 <1.25. The system consists of polarization maintaining (PM) fiber and PM-fiber components including tapered fiber bundle pump combiners, a single-mode to large mode area mode field adapter, and a fiber-coupled isolator. The laser components ultimately determine the system architecture and the limits of laser performance, particularly considering the immature and rapidly developing state of fiber components in the 2 μm wavelength regime. PMID:23037103

  6. Fiber-coupled diode laser systems up to 2-kW output power

    NASA Astrophysics Data System (ADS)

    Dorsch, Friedhelm; Bluemel, Veit; Schroeder, Matthias; Lorenzen, Dirk; Hennig, Petra; Wolff, Detlev

    2000-03-01

    High power diode laser bars and stacks are of great interest in industrial applications due to their high electro-optical efficiency, their small type of construction and maintenance free operation. With highly sophisticated beam shaping optics diode lasers can be used as pumping sources for solid state and fiber lasers and direct for material processing, e.g. welding, soldering and marking metals. We have developed different fiber coupled diode laser systems with output power up to greater than 2 kW cw into a spot 0 1.0 mm (power density greater than 250 kW/cm2) and systems with output power 170 W cw into a spot 0 0.38 mm (power density about 150 kW/cm2). The 2 kW system operates with a 0 1.5 mm fiber (N.A. 0.32) and consists of polarization and wavelength coupled stacks with an overall electro-optical efficiency of 23%. The smaller system operates either with a 0 0.6 mm (N.A. 0.22) or 0 0.4 mm (N.A. 0.33) fiber and consists of a single stack. Polarization and wavelength coupling will be realized in future. The overall electro-optical efficiency is about 27%.

  7. An Evaluation of the Additional Acoustic Power Needed to Overcome the Effects of a Test-Article's Absorption During Reverberant Chamber Acoustic Testing of Spaceflight Hardware

    NASA Technical Reports Server (NTRS)

    Hozman, Aron D.; Hughes, William O.

    2014-01-01

    The exposure of a customer's aerospace test-article to a simulated acoustic launch environment is typically performed in a reverberant acoustic test chamber. The acoustic pre-test runs that will ensure that the sound pressure levels of this environment can indeed be met by a test facility are normally performed without a test-article dynamic simulator of representative acoustic absorption and size. If an acoustic test facility's available acoustic power capability becomes maximized with the test-article installed during the actual test then the customer's environment requirement may become compromised. In order to understand the risk of not achieving the customer's in-tolerance spectrum requirement with the test-article installed, an acoustic power margin evaluation as a function of frequency may be performed by the test facility. The method for this evaluation of acoustic power will be discussed in this paper. This method was recently applied at the NASA Glenn Research Center Plum Brook Station's Reverberant Acoustic Test Facility for the SpaceX Falcon 9 Payload Fairing acoustic test program.

  8. An Evaluation of the Additional Acoustic Power Needed to Overcome the Effects of a Test-Article's Absorption during Reverberant Chamber Acoustic Testing of Spaceflight Hardware

    NASA Technical Reports Server (NTRS)

    Hozman, Aron D.; Hughes, William O.

    2014-01-01

    The exposure of a customers aerospace test-article to a simulated acoustic launch environment is typically performed in a reverberant acoustic test chamber. The acoustic pre-test runs that will ensure that the sound pressure levels of this environment can indeed be met by a test facility are normally performed without a test-article dynamic simulator of representative acoustic absorption and size. If an acoustic test facilitys available acoustic power capability becomes maximized with the test-article installed during the actual test then the customers environment requirement may become compromised. In order to understand the risk of not achieving the customers in-tolerance spectrum requirement with the test-article installed, an acoustic power margin evaluation as a function of frequency may be performed by the test facility. The method for this evaluation of acoustic power will be discussed in this paper. This method was recently applied at the NASA Glenn Research Center Plum Brook Stations Reverberant Acoustic Test Facility for the SpaceX Falcon 9 Payload Fairing acoustic test program.

  9. The Influence of Serial Carbohydrate Mouth Rinsing on Power Output during a Cycle Sprint

    PubMed Central

    Phillips, Shaun M.; Findlay, Scott; Kavaliauskas, Mykolas; Grant, Marie Clare

    2014-01-01

    The objective of the study was to investigate the influence of serial administration of a carbohydrate (CHO) mouth rinse on performance, metabolic and perceptual responses during a cycle sprint. Twelve physically active males (mean (± SD) age: 23.1 (3.0) years, height: 1.83 (0.07) m, body mass (BM): 86.3 (13.5) kg) completed the following mouth rinse trials in a randomized, counterbalanced, double-blind fashion; 1. 8 x 5 second rinses with a 25 ml CHO (6% w/v maltodextrin) solution, 2. 8 x 5 second rinses with a 25 ml placebo (PLA) solution. Following mouth rinse administration, participants completed a 30 second sprint on a cycle ergometer against a 0.075 g·kg-1 BM resistance. Eight participants achieved a greater peak power output (PPO) in the CHO trial, resulting in a significantly greater PPO compared with PLA (13.51 ± 2.19 vs. 13.20 ± 2.14 W·kg-1, p < 0.05). Magnitude inference analysis reported a likely benefit (81% likelihood) of the CHO mouth rinse on PPO. In the CHO trial, mean power output (MPO) showed a trend for being greater in the first 5 seconds of the sprint and lower for the remainder of the sprint compared with the PLA trial (p > 0.05). No significant between-trials difference was reported for fatigue index, perceived exertion, arousal and nausea levels, or blood lactate and glucose concentrations. Serial administration of a CHO mouth rinse may significantly improve PPO during a cycle sprint. This improvement appears confined to the first 5 seconds of the sprint, and may come at a greater relative cost for the remainder of the sprint. Key points The paper demonstrates that repeated administration of a carbohydrate mouth rinse can significantly improve peak power output during a single 30 second cycle sprint. The ergogenic effect of the carbohydrate mouth rinse may relate to the duration of exposure of the oral cavity to the mouth rinse, and associated greater stimulation of oral carbohydrate receptors. The significant increase in peak power

  10. The Influence of Serial Carbohydrate Mouth Rinsing on Power Output during a Cycle Sprint.

    PubMed

    Phillips, Shaun M; Findlay, Scott; Kavaliauskas, Mykolas; Grant, Marie Clare

    2014-05-01

    The objective of the study was to investigate the influence of serial administration of a carbohydrate (CHO) mouth rinse on performance, metabolic and perceptual responses during a cycle sprint. Twelve physically active males (mean (± SD) age: 23.1 (3.0) years, height: 1.83 (0.07) m, body mass (BM): 86.3 (13.5) kg) completed the following mouth rinse trials in a randomized, counterbalanced, double-blind fashion; 1. 8 x 5 second rinses with a 25 ml CHO (6% w/v maltodextrin) solution, 2. 8 x 5 second rinses with a 25 ml placebo (PLA) solution. Following mouth rinse administration, participants completed a 30 second sprint on a cycle ergometer against a 0.075 g·kg(-1) BM resistance. Eight participants achieved a greater peak power output (PPO) in the CHO trial, resulting in a significantly greater PPO compared with PLA (13.51 ± 2.19 vs. 13.20 ± 2.14 W·kg(-1), p < 0.05). Magnitude inference analysis reported a likely benefit (81% likelihood) of the CHO mouth rinse on PPO. In the CHO trial, mean power output (MPO) showed a trend for being greater in the first 5 seconds of the sprint and lower for the remainder of the sprint compared with the PLA trial (p > 0.05). No significant between-trials difference was reported for fatigue index, perceived exertion, arousal and nausea levels, or blood lactate and glucose concentrations. Serial administration of a CHO mouth rinse may significantly improve PPO during a cycle sprint. This improvement appears confined to the first 5 seconds of the sprint, and may come at a greater relative cost for the remainder of the sprint. Key pointsThe paper demonstrates that repeated administration of a carbohydrate mouth rinse can significantly improve peak power output during a single 30 second cycle sprint.The ergogenic effect of the carbohydrate mouth rinse may relate to the duration of exposure of the oral cavity to the mouth rinse, and associated greater stimulation of oral carbohydrate receptors.The significant increase in peak power

  11. Combination of spatial diversity and parallel decision feedback equalizer in a Single Input Multiple Output underwater acoustic communication system operating at very high frequencies

    NASA Astrophysics Data System (ADS)

    Skoro Kaskarovska, Violeta; Beaujean, Pierre-Philippe

    2013-05-01

    Single Input Multiple Output (SIMO) acoustic communication system using an adaptive spatial diversity combined with parallel Decision Feedback Equalizer (DFE) is presented in this document. The SIMO system operates at high frequencies with high data rate over a limited range (less than 200 m) in very shallow waters. The SIMO system consists of a single source transmitting Phase Shift Keying (PSK) messages modulated at 300 kHz and received by multiple receivers. In a first configuration, the symbols collected at each receiver are equalized using a decision feedback equalizer and combined using Maximum Ratio Combining (MRC). In a second configuration, the MRC outputs are used as decision symbols in the DFE. This second configuration is a form of turbo equalization: the process can be repeated over and over, leading to a better estimate of the received message as the number of iterations increases. The adaptive process of diversity is repeated until the best possible result is achieved or a predefined error criterion is met. Bit Error Rate (BER) and Signal-to-Noise-and-Interference Ratio (SNIR) are used as performance metrics of the acoustic channel. Experimental results using SIMO system with three, four or five receivers and pre-processed real recorded data demonstrate ability to improve the performance of the acoustic channel in challenging environments. Using received messages with non-zero BER, adaptive spatial diversity can achieve BER of 0% and increased SNIR of 3 dB with number of iterations depending on the number of receivers used.

  12. Acute negative effect of a hypertrophy-oriented training bout on subsequent upper-body power output.

    PubMed

    Baker, Daniel

    2003-08-01

    Athletes regularly combine maximal strength, power, and hypertrophy-oriented training within the same workout. Traditionally, it has been suggested that power-oriented exercises precede strength and hypertrophy-oriented training within a workout to avoid the possible negative effects that the latter types of training may have on power output. However, with regard to upper-body training, little study has been performed to verify this commonly held belief. The purpose of this study was to determine the extent, if any, of a high-repetition, short-rest-period, hypertrophy-oriented training dose on upper-body power output. Twenty-seven college-aged rugby league players were tested for average power output during bench press throws with a resistance of 40 kg (BT P40). The experimental group (Hyp, n = 15) then performed a typical hypertrophy-oriented work bout (3 x 10 at 65% 1 repetition maximum bench press, 1RM BP) before being retested for power output with the same resistance. In comparison with the control group (Con, n = 12), whose power output remained unchanged between the pre- and posttest periods, the Hyp group experienced a large, significant decrease in BT P40 power output. Even after further passive rest of 7 minutes, power output remained suppressed from the pretest values. Furthermore, the strongest 5 subjects experienced significantly larger percentage declines in power output than did the 5 less strong subjects. This study shows that a high-repetition, short-rest-period training can acutely decrease power output. Coaches should plan the order of exercises carefully when combining power and hypertrophy training.

  13. Predicting Power Output of Upper Body using the OMNI-RES Scale

    PubMed Central

    Bautista, Iker J.; Chirosa, Ignacio J.; Tamayo, Ignacio Martín; González, Andrés; Robinson, Joseph E.; Chirosa, Luis J.; Robertson, Robert J.

    2014-01-01

    The main aim of this study was to determine the optimal training zone for maximum power output. This was to be achieved through estimating mean bar velocity of the concentric phase of a bench press using a prediction equation. The values for the prediction equation would be obtained using OMNI–RES scale values of different loads of the bench press exercise. Sixty males (age 23.61 2.81 year; body height 176.29 6.73 cm; body mass 73.28 4.75 kg) voluntarily participated in the study and were tested using an incremental protocol on a Smith machine to determine one repetition maximum (1RM) in the bench press exercise. A linear regression analysis produced a strong correlation (r = −0.94) between rating of perceived exertion (RPE) and mean bar velocity (Velmean). The Pearson correlation analysis between real power output (PotReal) and estimated power (PotEst) showed a strong correlation coefficient of r = 0.77, significant at a level of p = 0.01. Therefore, the OMNI–RES scale can be used to predict Velmean in the bench press exercise to control the intensity of the exercise. The positive relationship between PotReal and PotEst allowed for the identification of a maximum power-training zone. PMID:25713677

  14. Effects of creatine monohydrate and polyethylene glycosylated creatine supplementation on muscular strength, endurance, and power output.

    PubMed

    Herda, Trent J; Beck, Travis W; Ryan, Eric D; Smith, Abbie E; Walter, Ashley A; Hartman, Michael J; Stout, Jeffrey R; Cramer, Joel T

    2009-05-01

    The purpose of this study was to examine the effects of a moderate dose of creatine monohydrate (CM) and two smaller doses of polyethylene glycosylated (PEG) creatine on muscular strength, endurance, and power output. Fifty-eight healthy men (mean +/- SD: age, 21 +/- 2 years; height, 176 +/- 6 cm; body mass [BM], 75 +/- 14 kg) volunteered and were randomly assigned to 1 of 4 groups: (a) placebo (PL; 3.6 g of microcrystalline cellulose; n = 15), (b) CM (5 g of creatine; n = 13), (c) small-dose PEG creatine (1.25 g of creatine: PEG1.25; n = 14), or (d) moderate-dose PEG creatine (2.50 g of creatine: PEG2.50; n = 16). Testing was conducted before (pre-) and after (post-) a 30-day supplementation period. Measurements included body mass, countermovement vertical jump (CVJ) height, power output during the Wingate test (peak power [PP] and mean power [MP]), 1 repetition maximum bench press (1RMBP), 1RM leg press (1RMLP) strength, and repetitions to failure at 80% of the 1RM for bench press (REPBP) and leg press (REPLP). BM and MP (W) increased (p power output, or endurance. When compared to the PL group, neither CM nor PEG creatine supplementation improved peak power output (CVJ or PP), MP, or muscle endurance (REPBP or REPLP). Thus, PEG creatine may have ergogenic effects that are comparable to those of CM, but with a smaller dose of creatine.

  15. Cardiac power output and its response to exercise in athletes and non-athletes.

    PubMed

    Klasnja, Aleksandar V; Jakovljevic, Djordje G; Barak, Otto F; Popadic Gacesa, Jelena Z; Lukac, Damir D; Grujic, Nikola G

    2013-05-01

    Cardiac power output (CPO) is an integrative measure of overall cardiac function as it accounts for both, flow- and pressure-generating capacities of the heart. The purpose of the present study was twofold: (i) to assess cardiac power output and its response to exercise in athletes and non-athletes and (ii) to determine the relationship between cardiac power output and reserve and selected measures of cardiac function and structure. Twenty male athletes and 32 age- and gender-matched healthy sedentary controls participated in this study. CPO was calculated as the product of cardiac output and mean arterial pressure, expressed in watts. Measures of hemodynamic status, cardiac structure and pumping capability were assessed by echocardiography. CPO was assessed at rest and after peak bicycle exercise. At rest, the two groups had similar values of cardiac power output (1·08 ± 0·2 W versus 1·1 ± 0·24 W, P>0·05), but the athletes demonstrated lower systolic blood pressure (109·5 ± 6·2 mmHg versus 117·2 ± 8·2 mmHg, P<0·05) and thicker posterior wall of the left ventricle (9·8 ± 1 mm versus 9 ± 1·1 mm, P<0·05). Peak CPO was higher in athletes (5·87 ± 0·75 W versus 5·4 ± 0·69 W, P<0·05) as was cardiac reserve (4·92 ± 0·66 W versus 4·26 ± 0·61 W, P<0·05), respectively. Peak exercise CPO and reserve were only moderately correlated with end-diastolic volume (r = 0·54; r = 0·46, P<0·05) and end-diastolic left ventricular internal diameter (r = 0·48; r = 0·42, P<0·05), respectively. Athletes demonstrated greater maximal cardiac pumping capability and reserve than non-athletes. The study provides new evidence that resting measures of cardiac structure and function need to be considered with caution in interpretation of maximal cardiac performance.

  16. Lack of maintenance of shortwave diathermy equipment has a negative impact on power output.

    PubMed

    Guirro, Rinaldo Roberto de Jesus; Guirro, Elaine Caldeira de Oliveira; Alves de Sousa, Natanael Teixeira

    2014-04-01

    Although shortwave diathermy has been widely used by physiotherapists, there are a few studies assessing the performance of the equipment in use. The aim of the present study was to evaluate the procedures adopted by physiotherapists as users of shortwave diathermy continuous (CSWD), as well as to measure the power output and frequency of CSWD equipment. [Subjects and Methods] Twenty-three physical therapists were interviewed and 23 CSWD equipment were evaluated. Admeasurement was carried out by using a standard phantom to simulate the electrode-skin distance, which ranged from 0.5 to 3.0 cm. Data analysis was performed by using descriptive statistics, ANOVA, and a post-hoc Tukey's test or Pearson's correlation coefficient. [Results] The questionnaires showed that 48% of the interviewees use the correct electrode-skin distance, 70% use a single electrical outlet, and 35% use a grounded electrical outlet, and that 48% of the physiotherapy tables and 61% of the plinths were made of wood. However, only 13% of the interviewees perform yearly preventive maintenance. The highest power (95.56 W) was achieved at electrode-skin distances ranging from 1.0 to 1.5 cm, with distances of 2.5 cm and 3.0 cm being null in four and eight equipment, respectively. There was a negative correlation between power output and electrode-skin distance as well as between power output and purchase date. [Conclusion] The physiotherapists involved in this study had inadequate knowledge about the correct use of CSWD equipment, which may adversely affect its performance and patient safety. PMID:24764633

  17. Lack of Maintenance of Shortwave Diathermy Equipment Has a Negative Impact on Power Output

    PubMed Central

    Guirro, Rinaldo Roberto de Jesus; Guirro, Elaine Caldeira de Oliveira; Alves de Sousa, Natanael Teixeira

    2014-01-01

    Although shortwave diathermy has been widely used by physiotherapists, there are a few studies assessing the performance of the equipment in use. The aim of the present study was to evaluate the procedures adopted by physiotherapists as users of shortwave diathermy continuous (CSWD), as well as to measure the power output and frequency of CSWD equipment. [Subjects and Methods] Twenty-three physical therapists were interviewed and 23 CSWD equipment were evaluated. Admeasurement was carried out by using a standard phantom to simulate the electrode-skin distance, which ranged from 0.5 to 3.0 cm. Data analysis was performed by using descriptive statistics, ANOVA, and a post-hoc Tukey’s test or Pearson’s correlation coefficient. [Results] The questionnaires showed that 48% of the interviewees use the correct electrode-skin distance, 70% use a single electrical outlet, and 35% use a grounded electrical outlet, and that 48% of the physiotherapy tables and 61% of the plinths were made of wood. However, only 13% of the interviewees perform yearly preventive maintenance. The highest power (95.56 W) was achieved at electrode-skin distances ranging from 1.0 to 1.5 cm, with distances of 2.5 cm and 3.0 cm being null in four and eight equipment, respectively. There was a negative correlation between power output and electrode-skin distance as well as between power output and purchase date. [Conclusion] The physiotherapists involved in this study had inadequate knowledge about the correct use of CSWD equipment, which may adversely affect its performance and patient safety. PMID:24764633

  18. Decreasing Power Output Increases Aerobic Contribution During Low-Volume Severe-Intensity Intermittent Exercise.

    PubMed

    Lisbôa, Felipe D; Salvador, Amadeo F; Raimundo, João A G; Pereira, Kayo L; de Aguiar, Rafael A; Caputo, Fabrizio

    2015-09-01

    High-intensity interval training applied at submaximal, maximal, and supramaximal intensities for exercising at V[Combining Dot Above]O2max (t95V[Combining Dot Above]O2max) has shown similar adaptation to low-volume sprint interval training among active subjects. Thus, the aim of the present study was to investigate t95V[Combining Dot Above]O2max during 2 different intermittent exercises in the severe-intensity domain (e.g., range of power outputs over which V[Combining Dot Above]O2max can be elicited during constant-load exercise) and to identify an exercise protocol that reduces the time required to promote higher aerobic demand. Eight active men (22 ± 2 years, 72 ± 5 kg, 174 ± 4 cm, 47 ± 8 ml·kg·min) completed the following protocols on a cycle ergometer: (a) incremental test, (b) determination of critical power (CP), (c) determination of the highest constant intensity (IHIGH) and the lowest exercise duration (TLOW) in which V[Combining Dot Above]O2max is attained, and (d) 2 exercise sessions in a randomized order that consisted of a constant power output (CPO) session at IHIGH and a decreasing power output (DPO) session that applied a decreasing work rate profile from IHIGH to 110% of CP. Time to exhaustion was significantly longer in DPO (371 ± 57 seconds vs. 225 ± 33 seconds). Moreover, t95V[Combining Dot Above]O2max (186 ± 72 seconds vs. 76 ± 49 seconds) and O2 consumed (29 ± 4 L vs. 17 ± 3 L) were higher in DPO when compared with the CPO protocol. In conclusion, data suggest that the application of a DPO protocol during intermittent exercise increases the time spent at high percentages of V[Combining Dot Above]O2max.

  19. Adaptive robust maximum power point tracking control for perturbed photovoltaic systems with output voltage estimation.

    PubMed

    Koofigar, Hamid Reza

    2016-01-01

    The problem of maximum power point tracking (MPPT) in photovoltaic (PV) systems, despite the model uncertainties and the variations in environmental circumstances, is addressed. Introducing a mathematical description, an adaptive sliding mode control (ASMC) algorithm is first developed. Unlike many previous investigations, the output voltage is not required to be sensed and the upper bound of system uncertainties and the variations of irradiance and temperature are not required to be known. Estimating the output voltage by an update law, an adaptive-based H∞ tracking algorithm is then developed for the case the perturbations are energy-bounded. The stability analysis is presented for the proposed tracking control schemes, based on the Lyapunov stability theorem. From a comparison viewpoint, some numerical and experimental studies are also presented and discussed. PMID:26606851

  20. Adaptive robust maximum power point tracking control for perturbed photovoltaic systems with output voltage estimation.

    PubMed

    Koofigar, Hamid Reza

    2016-01-01

    The problem of maximum power point tracking (MPPT) in photovoltaic (PV) systems, despite the model uncertainties and the variations in environmental circumstances, is addressed. Introducing a mathematical description, an adaptive sliding mode control (ASMC) algorithm is first developed. Unlike many previous investigations, the output voltage is not required to be sensed and the upper bound of system uncertainties and the variations of irradiance and temperature are not required to be known. Estimating the output voltage by an update law, an adaptive-based H∞ tracking algorithm is then developed for the case the perturbations are energy-bounded. The stability analysis is presented for the proposed tracking control schemes, based on the Lyapunov stability theorem. From a comparison viewpoint, some numerical and experimental studies are also presented and discussed.

  1. Acoustics

    NASA Technical Reports Server (NTRS)

    Goodman, Jerry R.; Grosveld, Ferdinand

    2007-01-01

    The acoustics environment in space operations is important to maintain at manageable levels so that the crewperson can remain safe, functional, effective, and reasonably comfortable. High acoustic levels can produce temporary or permanent hearing loss, or cause other physiological symptoms such as auditory pain, headaches, discomfort, strain in the vocal cords, or fatigue. Noise is defined as undesirable sound. Excessive noise may result in psychological effects such as irritability, inability to concentrate, decrease in productivity, annoyance, errors in judgment, and distraction. A noisy environment can also result in the inability to sleep, or sleep well. Elevated noise levels can affect the ability to communicate, understand what is being said, hear what is going on in the environment, degrade crew performance and operations, and create habitability concerns. Superfluous noise emissions can also create the inability to hear alarms or other important auditory cues such as an equipment malfunctioning. Recent space flight experience, evaluations of the requirements in crew habitable areas, and lessons learned (Goodman 2003; Allen and Goodman 2003; Pilkinton 2003; Grosveld et al. 2003) show the importance of maintaining an acceptable acoustics environment. This is best accomplished by having a high-quality set of limits/requirements early in the program, the "designing in" of acoustics in the development of hardware and systems, and by monitoring, testing and verifying the levels to ensure that they are acceptable.

  2. The effect of preignition on cylinder temperatures, pressures, power output, and piston failures

    NASA Technical Reports Server (NTRS)

    Corrington, Lester C; Fisher, William F

    1947-01-01

    An investigation was conducted using a cylinder of a V-type liquid-cooled engine to observe the behavior of the cylinder when operated under preignition conditions. Data were recorded that showed cylinder-head temperatures, time of ignition, engine speed, power output, and change in maximum cylinder pressure as a function of time as the engine entered preignition and was allowed to operate under preignition conditions for a short time. The effects of the following variables on the engine behavior during preignition were investigated: fuel-air ratio, power level, aromatic content of fuel, engine speed, mixture temperature, and preignition source. The power levels at which preignition would cause complete piston failure for the selected engine operating conditions and the types of failure encountered when using various values of clearance between the piston and cylinder barrel were determined. The fuels used had performance numbers high enough to preclude any possibility of knock throughout the test program.

  3. 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.

  4. In situ measurements of wind and current speed and relationship between output power and turbulence

    NASA Astrophysics Data System (ADS)

    Duran Medina, Olmo; Schmitt, François G.; Sentchev, Alexei; Calif, Rudy

    2015-04-01

    In a context of energy transition, wind and tidal energy are sources of clean energy with the potential of partially satisfying the growing demand. The main problem of this type of energy, and other types of renewable energy remains the discontinuity of the electric power produced in different scales, inducing large fluctuations also called intermittency. This intermittency of wind and tidal energy is inherent to the turbulent nature of wind and marine currents. We consider this intermittent power production in strong relation with the turbulent intermittency of the resource. The turbulence theory is multifractal energy cascades models, a classic in physics of turbulence. From earlier studies in atmospheric sciences, we learn that wind speed and the aggregate power output are intermittent and multifractal over a wide range of scales [Calif and Schmitt 2014]. We want to extend this study to a marine current turbine and compare the scaling properties for those renewable energy sources. We consider here coupling between simultaneous velocity time series and output power from a wind turbine and a marine current turbine. Wind turbine data were obtained from Denmark and marine current data from Western Scheldt, Belgium where a prototype of a vertical and horizontal marine current turbines are tested. After an estimation of their Fourier density power spectra, we study their scaling properties in Kolmogorov's theory and the framework of fully developed turbulence. Hence, we employ a Hilbert-based methodology, namely arbitrary-order Hilbert spectral analysis [Calif et al. 2013a, 2013b] to characterize the intermittent property of the wind and marine current velocity in order to characterize the intermittent nature of the fluid. This method is used in order to obtain the spectrum and the corresponding power law for non-linear and non-stationary time series. The goal is to study the non-linear transfer characteristics in a multi-scale and multi-intensity framework.

  5. Stabilized Acoustic Levitation of Dense Materials Using a High-Powered Siren

    NASA Technical Reports Server (NTRS)

    Gammell, P. M.; Croonquist, A.; Wang, T. G.

    1982-01-01

    Stabilized acoustic levitation and manipulation of dense (e.g., steel) objects of 1 cm diameter, using a high powered siren, was demonstrated in trials that investigated the harmonic content and spatial distribution of the acoustic field, as well as the effect of sample position and reflector geometries on the acoustic field. Although further optimization is possible, the most stable operation achieved is expected to be adequate for most containerless processing applications. Best stability was obtained with an open reflector system, using a flat lower reflector and a slightly concave upper one. Operation slightly below resonance enhances stability as this minimizes the second harmonic, which is suspected of being a particularly destabilizing influence.

  6. Muscle coordination limits efficiency and power output of human limb movement under a wide range of mechanical demands.

    PubMed

    Blake, Ollie M; Wakeling, James M

    2015-12-01

    This study investigated the influence of cycle frequency and workload on muscle coordination and the ensuing relationship with mechanical efficiency and power output of human limb movement. Eleven trained cyclists completed an array of cycle frequency (cadence)-power output conditions while excitation from 10 leg muscles and power output were recorded. Mechanical efficiency was maximized at increasing cadences for increasing power outputs and corresponded to muscle coordination and muscle fiber type recruitment that minimized both the total muscle excitation across all muscles and the ineffective pedal forces. Also, maximum efficiency was characterized by muscle coordination at the top and bottom of the pedal cycle and progressive excitation through the uniarticulate knee, hip, and ankle muscles. Inefficiencies were characterized by excessive excitation of biarticulate muscles and larger duty cycles. Power output and efficiency were limited by the duration of muscle excitation beyond a critical cadence (120-140 rpm), with larger duty cycles and disproportionate increases in muscle excitation suggesting deteriorating muscle coordination and limitations of the activation-deactivation capabilities. Most muscles displayed systematic phase shifts of the muscle excitation relative to the pedal cycle that were dependent on cadence and, to a lesser extent, power output. Phase shifts were different for each muscle, thereby altering their mechanical contribution to the pedaling action. This study shows that muscle coordination is a key determinant of mechanical efficiency and power output of limb movement across a wide range of mechanical demands and that the excitation and coordination of the muscles is limited at very high cycle frequencies.

  7. Control Strategies for Smoothing of Output Power of Wind Energy Conversion Systems

    NASA Astrophysics Data System (ADS)

    Pratap, Alok; Urasaki, Naomitsu; Senju, Tomonobu

    2013-10-01

    This article presents a control method for output power smoothing of a wind energy conversion system (WECS) with a permanent magnet synchronous generator (PMSG) using the inertia of wind turbine and the pitch control. The WECS used in this article adopts an AC-DC-AC converter system. The generator-side converter controls the torque of the PMSG, while the grid-side inverter controls the DC-link and grid voltages. For the generator-side converter, the torque command is determined by using the fuzzy logic. The inputs of the fuzzy logic are the operating point of the rotational speed of the PMSG and the difference between the wind turbine torque and the generator torque. By means of the proposed method, the generator torque is smoothed, and the kinetic energy stored by the inertia of the wind turbine can be utilized to smooth the output power fluctuations of the PMSG. In addition, the wind turbines shaft stress is mitigated compared to a conventional maximum power point tracking control. Effectiveness of the proposed method is verified by the numerical simulations.

  8. Techniques for increasing output power from mode-locked semiconductor lasers

    SciTech Connect

    Mar, A.; Vawter, G.A.

    1996-02-01

    Mode-locked semiconductor lasers have drawn considerable attention as compact, reliable, and relatively inexpensive sources of short optical pulses. Advances in the design of such lasers have resulted in vast improvements in pulsewidth and noise performance, at a very wide range of repetition rates. An attractive application for these lasers would be to serve as alternatives for large benchtop laser systems such as dye lasers and solid-state lasers. However, mode-locked semiconductor lasers have not yet approached the performance of such systems in terms of output power. Different techniques for overcoming the problem of low output power from mode-locked semiconductor lasers will be discussed. Flared and arrayed lasers have been used successfully to increase the pulse saturation energy limit by increasing the gain cross section. Further improvements have been achieved by use of the MOPA configuration, which utilizes a flared semiconductor amplifier s amplify pulses to energies of 120 pJ and peak powers of nearly 30W.

  9. Acoustic energy harvesting based on a planar acoustic metamaterial

    NASA Astrophysics Data System (ADS)

    Qi, Shuibao; Oudich, Mourad; Li, Yong; Assouar, Badreddine

    2016-06-01

    We theoretically report on an innovative and practical acoustic energy harvester based on a defected acoustic metamaterial (AMM) with piezoelectric material. The idea is to create suitable resonant defects in an AMM to confine the strain energy originating from an acoustic incidence. This scavenged energy is converted into electrical energy by attaching a structured piezoelectric material into the defect area of the AMM. We show an acoustic energy harvester based on a meta-structure capable of producing electrical power from an acoustic pressure. Numerical simulations are provided to analyze and elucidate the principles and the performances of the proposed system. A maximum output voltage of 1.3 V and a power density of 0.54 μW/cm3 are obtained at a frequency of 2257.5 Hz. The proposed concept should have broad applications on energy harvesting as well as on low-frequency sound isolation, since this system acts as both acoustic insulator and energy harvester.

  10. Steering by Hearing: A Bat’s Acoustic Gaze Is Linked to Its Flight Motor Output by a Delayed, Adaptive Linear Law

    PubMed Central

    Ghose, Kaushik; Moss, Cynthia F.

    2012-01-01

    Adaptive behaviors require sensorimotor computations that convert information represented initially in sensory coordinates to commands for action in motor coordinates. Fundamental to these computations is the relationship between the region of the environment sensed by the animal (gaze) and the animal’s locomotor plan. Studies of visually guided animals have revealed an anticipatory relationship between gaze direction and the locomotor plan during target-directed locomotion. Here, we study an acoustically guided animal, an echolocating bat, and relate acoustic gaze (direction of the sonar beam) to flight planning as the bat searches for and intercepts insect prey. We show differences in the relationship between gaze and locomotion as the bat progresses through different phases of insect pursuit. We define acoustic gaze angle, θgaze, to be the angle between the sonar beam axis and the bat’s flight path. We show that there is a strong linear linkage between acoustic gaze angle at time t [θgaze(t)] and flight turn rate at time t + τ into the future [θ̇flight (t + τ)], which can be expressed by the formula θ̇flight (t + τ) = kθgaze(t). The gain, k, of this linkage depends on the bat’s behavioral state, which is indexed by its sonar pulse rate. For high pulse rates, associated with insect attacking behavior, k is twice as high compared with low pulse rates, associated with searching behavior. We suggest that this adjustable linkage between acoustic gaze and motor output in a flying echolocating bat simplifies the transformation of auditory information to flight motor commands. PMID:16467518

  11. Postexercise heart rate recovery in children: relationship with power output, blood pH, and lactate.

    PubMed

    Buchheit, Martin; Duché, Pascale; Laursen, Paul B; Ratel, Sébastien

    2010-04-01

    The aim of the present study was to determine whether differences in age-related heart rate recovery (HRR) kinetics were associated with differences in power output, blood lactate concentration ([La]b), and acidosis among children, adolescents, and adults. Ten prepubertal boys (aged 9.6 +/- 0.7 years), 6 pubertal boys (aged 15.2 +/- 0.8 years), and 7 men (aged 20.4 +/- 1.0 years) performed 10 repeated 10-s all-out cycling sprints, interspersed with 5-min passive recovery intervals. Mean power output (MPO) was measured during each sprint, and HRR, [La]b, and acidosis (pHb) were determined immediately after each sprint. Children displayed a shorter time constant of the primary component of HRR than adolescents and adults (17.5 +/- 4.1 vs. 38.0 +/- 5.3 and 36.9 +/- 4.9 s, p < 0.001 for both), but no difference was observed between adolescents and adults (p = 1.00). MPO, [La]b, and pHb were also lower in children compared with the other 2 groups (p < 0.001 for both). When data were pooled, HRR was significantly correlated with MPO (r = 0.48, p < 0.001), [La]b (r = 0.58, p < 0.001), and pHb (r = -0.60, p < 0.001). Covarying for MPO, [La]b, or pHb abolished the between-group differences in HRR (p = 0.42, p = 0.19, and p = 0.16, respectively). Anaerobic glycolytic contribution and power output explained a significant portion of the HRR variance following high-intensity intermittent exercise. The faster HRR kinetic observed in children appears to be related, at least in part, to their lower work rate and inherent lack of anaerobic metabolic capacity. PMID:20383224

  12. Effects of age and mode of exercise on power output profiles during repeated sprints.

    PubMed

    Ratel, Sébastien; Williams, Craig A; Oliver, Jonathan; Armstrong, Neil

    2004-06-01

    The aim of this study was to compare power output profiles during repeated cycling and running sprints in children and adults. On two separate visits, 12 boys [11.7 (0.5) years] and 13 men [22.1 (2.9) years] performed ten consecutive 10-s sprints interspersed with 15-s recovery intervals on a non-motorised treadmill and cycle ergometer. Peak (PPO) and mean (MPO) power outputs were measured during each sprint. Capillary fingertip blood samples were drawn at rest and 3 min after the final sprint to measure lactate accumulation (Delta[La]). PPO and MPO decreased significantly more in adults compared to children over the ten sprints irrespective of the mode of exercise (P<0.001). PPO decreased by a similar amount during running and cycling in children (-17.7 versus -14.3%, P>0.05, respectively) and adults (-43.3 versus -40.0%, P>0.05, respectively). In contrast, MPO decreased significantly more during running compared to cycling both in children (-28.9 versus -18.7%, P<0.05) and adults (-47.0 versus -36.7%, P<0.05). The greater decrease in MPO during running compared to cycling was accompanied in children by significantly higher Delta[La] values (7.7 versus 4.1 mmol l(-1), P<0.001). In adults, blood lactate accumulation tended to be higher during running than cycling (12.7 versus 10.8 mmol l(-1), P=0.06). To conclude, adults displayed a greater decrement in power output compared to children over the ten repeated running and cycling sprints. Furthermore, children and adults experienced greater fatigue during running compared to cycling. This last result may be attributed to additional muscle recruitment during sprint running. PMID:15045504

  13. Effects of antenna length and material on output power and detection of miniature radio transmitters

    USGS Publications Warehouse

    Beeman, J.W.; Bower, N.; Juhnke, S.; Dingmon, L.; Van Den, Tillaart; Thomas, T.

    2007-01-01

    The optimal antenna of transmitters used in small aquatic animals is often a compromise between efficient radio wave propagation and effects on animal behavior. Radio transmission efficiency generally increases with diameter and length of the conductor, but increased antenna length or weight can adversely affect animal behavior. We evaluated the effects of changing antenna length and material on the subsequent tag output power, reception, and detection of tagged fish. In a laboratory, we compared the relative signal strengths in water of 150 MHz transmitters over a range of antenna lengths (from 6 to 30 cm) and materials (one weighing about half of the other). The peak relative signal strengths were at 20 and 22 cm, which are approximately one wavelength underwater at the test frequency. The peak relative signal strengths at these lengths were approximately 50% greater than those of 30 cm antennas, a length commonly used in fisheries research. Few significant differences were present in distances for the operator to hear or the telemetry receiver to decode transmitters from a boat-mounted receiving system based on antenna length, but the percent of tagged fish detected passing a hydroelectric dam fitted with an array of receiving systems was significantly greater at the antenna length with peak output power in laboratory tests. This study indicates careful choice of antenna length and material of small transmitters can be used to reduce weight and possible antenna effects on animal behavior, to maximize tag output power and detection, or to balance these factors based on the needs of the application. ?? 2007 Springer Science+Business Media B.V.

  14. Zinc oxide integrated area efficient high output low power wavy channel thin film transistor

    SciTech Connect

    Hanna, A. N.; Ghoneim, M. T.; Bahabry, R. R.; Hussain, A. M.; Hussain, M. M.

    2013-11-25

    We report an atomic layer deposition based zinc oxide channel material integrated thin film transistor using wavy channel architecture allowing expansion of the transistor width in the vertical direction using the fin type features. The experimental devices show area efficiency, higher normalized output current, and relatively lower power consumption compared to the planar architecture. This performance gain is attributed to the increased device width and an enhanced applied electric field due to the architecture when compared to a back gated planar device with the same process conditions.

  15. Enhanced Power Output of a Triboelectric Nanogenerator Composed of Electrospun Nanofiber Mats Doped with Graphene Oxide

    PubMed Central

    Huang, Tao; Lu, Mingxia; Yu, Hao; Zhang, Qinghong; Wang, Hongzhi; Zhu, Meifang

    2015-01-01

    We developed a book-shaped triboelectric nanogenerator (TENG) that consists of electrospun polyvinylidene fluoride (PVDF) and poly(3-hydroxybutyrate-co-3-hydroxyvalerate) (PHBV) nanofibers to effectively harvest mechanical energy. The dispersed graphene oxide in the PVDF nanofibers acts as charge trapping sites, which increased the interface for charge storage as well as the output performance of the TENG. The book-shaped TENG was used as a direct power source to drive small electronics such as LED bulbs. This study proved that it is possible to improve the performance of TENGs using composite materials. PMID:26387825

  16. Ferroelectric dipole electrets for output power enhancement in electrostatic vibration energy harvesters

    NASA Astrophysics Data System (ADS)

    Asanuma, Haruhiko; Oguchi, Hiroyuki; Hara, Motoaki; Yoshida, Ryo; Kuwano, Hiroki

    2013-10-01

    We propose a ferroelectric dipole electret composed of polarized lead zirconate titanate. Deep insight into the physics behind the parallel plate capacitor theoretically predicts that we can extract large electric field near the surface of the ferroelectric dipole electret by increasing its surface charge density and thickness. Experiment for ferroelectric dipole electret shows good agreement with the theory. The maximum output power density of electrostatic vibration energy harvesters using the ferroelectric dipole electret was 78 μW/cm3, a three-fold increase over a conventional polymer electret. Our results will pave the way for use of ferroelectrics as electrets.

  17. Elimination of output-current transients in the MFTF sustaining neutral-beam-arc power supplies

    NASA Astrophysics Data System (ADS)

    Vanness, H. W.; Mayhall, D. J.; Wilson, J. H.

    1981-10-01

    The twenty-three MFTF sustaining neutral beam arc power supplies were designed to provide 0.3 to 30 second output pulses over a range of 24 to 71 volts and 600 to 4000 amperes at 10 percent duty. For economic reasons, the circuit design consists of a 12 pulse rectifier which is synchronously switched on and off by a three phase electromechanical contactor in the primary ac input. Analysis of the problem, various possible solution considered, and the simple and inexpensive solution adopted for use are described.

  18. Enhanced Power Output of a Triboelectric Nanogenerator Composed of Electrospun Nanofiber Mats Doped with Graphene Oxide

    NASA Astrophysics Data System (ADS)

    Huang, Tao; Lu, Mingxia; Yu, Hao; Zhang, Qinghong; Wang, Hongzhi; Zhu, Meifang

    2015-09-01

    We developed a book-shaped triboelectric nanogenerator (TENG) that consists of electrospun polyvinylidene fluoride (PVDF) and poly(3-hydroxybutyrate-co-3-hydroxyvalerate) (PHBV) nanofibers to effectively harvest mechanical energy. The dispersed graphene oxide in the PVDF nanofibers acts as charge trapping sites, which increased the interface for charge storage as well as the output performance of the TENG. The book-shaped TENG was used as a direct power source to drive small electronics such as LED bulbs. This study proved that it is possible to improve the performance of TENGs using composite materials.

  19. Mobility power flow analysis of an L-shaped plate structure subjected to acoustic excitation

    NASA Technical Reports Server (NTRS)

    Cuschieri, J. M.

    1989-01-01

    An analytical investigation based on the Mobility Power Flow method is presented for the determination of the vibrational response and power flow for two coupled flat plate structures in an L-shaped configuration, subjected to acoustical excitation. The principle of the mobility power flow method consists of dividing the global structure into a series of subsystems coupled together using mobility functions. Each separate subsystem is analyzed independently to determine the structural mobility functions for the junction and excitation locations. The mobility functions, together with the characteristics of the junction between the subsystems, are then used to determine the response of the global structure and the power flow. In the coupled plate structure considered here, mobility power flow expressions are derived for excitation by an incident acoustic plane wave. In this case, the forces (acoustic pressures) acting on the structure are dependent on the response of the structure because of the scattered pressure component. The interaction between the structure and the fluid leads to the derivation of a corrected mode shape for the plates' normal surface velocity and also for the structure mobility functions. The determination of the scattered pressure components in the expressions for the power flow represents an additional component in the power flow balance for the source plate and the receiver plate. This component represents the radiated acoustical power from the plate structure.

  20. Aeroacoustics of volcanic jets: Acoustic power estimation and jet velocity dependence

    NASA Astrophysics Data System (ADS)

    Matoza, Robin S.; Fee, David; Neilsen, Tracianne B.; Gee, Kent L.; Ogden, Darcy E.

    2013-12-01

    A fundamental goal of volcano acoustics is to relate observed infrasonic signals to the eruptive processes generating them. A link between acoustic power Πacoustic analogy theory). We reexamine this approach in the context of the current understanding of jet noise, using data from a laboratory jet, a full-scale military jet aircraft, and a full-scale rocket motor. Accurate estimates of Πacoustic field experiments. Typical volcano acoustic data better represent point measurements of acoustic intensity Iacoustic intensity differ from those for acoustic power and are of the form Iacoustic data and thus requires modification. Quantitative integration of field, numerical, and laboratory studies within a modern aeroacoustics framework will lead to a more accurate relationship between volcanic infrasound and eruption parameters.

  1. The mechanical power output and hydromechanical efficiency of northern pike (Esox lucius) fast-starts

    PubMed

    Frith; Blake

    1995-01-01

    The mechanical power output and hydrodynamic efficiency of northern pike, Esox lucius, during acceleration from rest (fast-start) are calculated from hydrodynamic theory for two kinematic patterns, C-starts (used in escape) and S-starts (used in prey capture). The Weihs model is employed and modified to calculate the mechanical power produced by a fish during a fast-start. A term is included for the power required to accelerate body sections laterally. Lateral deceleration of fish body sections and their associated added mass are expressed as an active process requiring energy expenditure or as a passive process requiring no energy expenditure. In addition, two methods of calculating useful power (the power used to accelerate the virtual mass of the fish, i.e. fish body mass + longitudinal added mass, in the direction of motion), one derived from the Weihs model and the second by summing the changes in kinetic energy of the virtual mass of the fish during a fast-start, are compared and found to give similar estimates of useful power (not significantly different; differences average 22 %). Comparisons of the kinematics and performance of C- and S-starts reveal that C-starts are consistently terminated after two tail flips (stages 1 and 2) whereas S-starts continue for 3­6 tail flips (stages 3­6). In addition, acceleration during C-starts is more rapid and velocities are higher (2.3­2.8 m s-1) than during S-starts (0.8­1.8 m s-1) over the first 100 ms. However, the peak velocities achieved during S-starts and C-starts are similar over the duration of a fast-start. The superior acceleration rates achieved during the initial stages of a C-start can be explained, in part, by the use of greater maximum angles of attack, higher lateral and perpendicular velocities and larger maximum forces by the caudal fin. Hydrodynamic efficiencies for fast-starts range from 0.16 to 0.39, values that are lower than those observed during either burst-and-coast or steady swimming

  2. Stirling converters for space dynamic power concepts with 2 to 130 W{sub e} output

    SciTech Connect

    Ross, B.A.

    1995-12-31

    Three innovative Stirling converter concepts are described. Two concepts are based on Pluto Fast Flyby (PFF) mission requirements, where two General Purpose Heat Source (GPHS) modules provide the thermal input. The first concept (PFF2) considers a power system with two opposed Stirling converters; the second concept (PFF4) considers four opposed Stirling converters. For both concepts the Stirling converters are designed to vary their power production capability to compensate for the failure of one Stirling converter. While the net thermal efficiency of PFF4 is a few percentage points lower than PFF2, the total Stirling converter mass of PFF4 is half that for PFF2. The third concept (ITTI) is designed to supply 2 watts of power for weather stations on the Martian surface. The predicted thermal performance of the ITTI is low compared to PFF2 and PFF4, yet the ITTI concept offers significant advantages compared to currently available power systems at the 2-watt power level. All three concepts are based on long-life technology demonstrated by an 11-watt output Stirling generator that as of March 1995 has accumulated over 15,000 operating hours without maintenance.

  3. Efficiency at maximum power output of quantum heat engines under finite-time operation.

    PubMed

    Wang, Jianhui; He, Jizhou; Wu, Zhaoqi

    2012-03-01

    We study the efficiency at maximum power, η(m), of irreversible quantum Carnot engines (QCEs) that perform finite-time cycles between a hot and a cold reservoir at temperatures T(h) and T(c), respectively. For QCEs in the reversible limit (long cycle period, zero dissipation), η(m) becomes identical to the Carnot efficiency η(C)=1-T(c)/T(h). For QCE cycles in which nonadiabatic dissipation and the time spent on two adiabats are included, the efficiency η(m) at maximum power output is bounded from above by η(C)/(2-η(C)) and from below by η(C)/2. In the case of symmetric dissipation, the Curzon-Ahlborn efficiency η(CA)=1-√(T(c)/T(h)) is recovered under the condition that the time allocation between the adiabats and the contact time with the reservoir satisfy a certain relation.

  4. Updated Eastern Interconnect Wind Power Output and Forecasts for ERGIS: July 2012

    SciTech Connect

    Pennock, K.

    2012-10-01

    AWS Truepower, LLC (AWST) was retained by the National Renewable Energy Laboratory (NREL) to update wind resource, plant output, and wind power forecasts originally produced by the Eastern Wind Integration and Transmission Study (EWITS). The new data set was to incorporate AWST's updated 200-m wind speed map, additional tall towers that were not included in the original study, and new turbine power curves. Additionally, a primary objective of this new study was to employ new data synthesis techniques developed for the PJM Renewable Integration Study (PRIS) to eliminate diurnal discontinuities resulting from the assimilation of observations into mesoscale model runs. The updated data set covers the same geographic area, 10-minute time resolution, and 2004?2006 study period for the same onshore and offshore (Great Lakes and Atlantic coast) sites as the original EWITS data set.

  5. Power output of skinned skeletal muscle fibres from the cheetah (Acinonyx jubatus).

    PubMed

    West, Timothy G; Toepfer, Christopher N; Woledge, Roger C; Curtin, Nancy A; Rowlerson, Anthea; Kalakoutis, Michaeljohn; Hudson, Penny; Wilson, Alan M

    2013-08-01

    Muscle samples were taken from the gluteus, semitendinosus and longissimus muscles of a captive cheetah immediately after euthanasia. Fibres were 'skinned' to remove all membranes, leaving the contractile filament array intact and functional. Segments of skinned fibres from these cheetah muscles and from rabbit psoas muscle were activated at 20°C by a temperature-jump protocol. Step and ramp length changes were imposed after active stress had developed. The stiffness of the non-contractile ends of the fibres (series elastic component) was measured at two different stress values in each fibre; stiffness was strongly dependent on stress. Using these stiffness values, the speed of shortening of the contractile component was evaluated, and hence the power it was producing. Fibres were analysed for myosin heavy chain content using gel electrophoresis, and identified as either slow (type I) or fast (type II). The power output of cheetah type II fibre segments was 92.5±4.3 W kg(-1) (mean ± s.e., 14 fibres) during shortening at relative stress 0.15 (the stress during shortening/isometric stress). For rabbit psoas fibre segments (presumably type IIX) the corresponding value was significantly higher (P<0.001), 119.7±6.2 W kg(-1) (mean ± s.e., 7 fibres). These values are our best estimates of the maximum power output under the conditions used here. Thus, the contractile filament power from cheetah was less than that of rabbit when maximally activated at 20°C, and does not account for the superior locomotor performance of the cheetah.

  6. Effect of isokinetic cycling versus weight training on maximal power output and endurance performance in cycling.

    PubMed

    Koninckx, Erwin; Van Leemputte, Marc; Hespel, Peter

    2010-07-01

    The aim of this study was to compare the effects of a weight training program for the leg extensors with isokinetic cycling training (80 rpm) on maximal power output and endurance performance. Both strength training interventions were incorporated twice a week in a similar endurance training program of 12 weeks. Eighteen trained male cyclists (VO(2peak) 60 +/- 1 ml kg(-1) min(-1)) were grouped into the weight training (WT n = 9) or the isokinetic training group (IT n = 9) matched for training background and sprint power (P (max)), assessed from five maximal sprints (5 s) on an isokinetic bicycle ergometer at cadences between 40 and 120 rpm. Crank torque was measured (1 kHz) to determine the torque distribution during pedaling. Endurance performance was evaluated by measuring power, heart rate and lactate during a graded exercise test to exhaustion and a 30-min performance test. All tests were performed on subjects' individual race bicycle. Knee extension torque was evaluated isometrically at 115 degrees knee angle and dynamically at 200 degrees s(-1) using an isokinetic dynamometer. P (max) at 40 rpm increased in both the groups (~15%; P < 0.05). At 120 rpm, no improvement of P (max) was found in the IT training group, which was possibly related to an observed change in crank torque at high cadences (P < 0.05). Both groups improved their power output in the 30-min performance test (P < 0.05). Isometric knee extension torque increased only in WT (P < 0.05). In conclusion, at low cadences, P (max) improved in both training groups. However, in the IT training group, a disturbed pedaling technique compromises an improvement of P (max) at high cadences.

  7. A comparison of power output from linear and nonlinear kinetic energy harvesters using real vibration data

    NASA Astrophysics Data System (ADS)

    Beeby, Stephen P.; Wang, Leran; Zhu, Dibin; Weddell, Alex S.; Merrett, Geoff V.; Stark, Bernard; Szarka, Gyorgy; Al-Hashimi, Bashir M.

    2013-07-01

    The design of vibration energy harvesters (VEHs) is highly dependent upon the characteristics of the environmental vibrations present in the intended application. VEHs can be linear resonant systems tuned to particular frequencies or nonlinear systems with either bistable operation or a Duffing-type response. This paper provides detailed vibration data from a range of applications, which has been made freely available for download through the Energy Harvesting Network’s online data repository. In particular, this research shows that simulation is essential in designing and selecting the most suitable vibration energy harvester for particular applications. This is illustrated through C-based simulations of different types of VEHs, using real vibration data from a diesel ferry engine, a combined heat and power pump, a petrol car engine and a helicopter. The analysis shows that a bistable energy harvester only has a higher output power than a linear or Duffing-type nonlinear energy harvester with the same Q-factor when it is subjected to white noise vibration. The analysis also indicates that piezoelectric transduction mechanisms are more suitable for bistable energy harvesters than electromagnetic transduction. Furthermore, the linear energy harvester has a higher output power compared to the Duffing-type nonlinear energy harvester with the same Q factor in most cases. The Duffing-type nonlinear energy harvester can generate more power than the linear energy harvester only when it is excited at vibrations with multiple peaks and the frequencies of these peaks are within its bandwidth. Through these new observations, this paper illustrates the importance of simulation in the design of energy harvesting systems, with particular emphasis on the need to incorporate real vibration data.

  8. Logarithmic and power law input-output relations in sensory systems with fold-change detection.

    PubMed

    Adler, Miri; Mayo, Avi; Alon, Uri

    2014-08-01

    Two central biophysical laws describe sensory responses to input signals. One is a logarithmic relationship between input and output, and the other is a power law relationship. These laws are sometimes called the Weber-Fechner law and the Stevens power law, respectively. The two laws are found in a wide variety of human sensory systems including hearing, vision, taste, and weight perception; they also occur in the responses of cells to stimuli. However the mechanistic origin of these laws is not fully understood. To address this, we consider a class of biological circuits exhibiting a property called fold-change detection (FCD). In these circuits the response dynamics depend only on the relative change in input signal and not its absolute level, a property which applies to many physiological and cellular sensory systems. We show analytically that by changing a single parameter in the FCD circuits, both logarithmic and power-law relationships emerge; these laws are modified versions of the Weber-Fechner and Stevens laws. The parameter that determines which law is found is the steepness (effective Hill coefficient) of the effect of the internal variable on the output. This finding applies to major circuit architectures found in biological systems, including the incoherent feed-forward loop and nonlinear integral feedback loops. Therefore, if one measures the response to different fold changes in input signal and observes a logarithmic or power law, the present theory can be used to rule out certain FCD mechanisms, and to predict their cooperativity parameter. We demonstrate this approach using data from eukaryotic chemotaxis signaling.

  9. Enhancement of output power in spin torque nano-oscillator using heterogeneous layer

    NASA Astrophysics Data System (ADS)

    Bhoomeeswaran, H.; Sabareesan, P.

    2016-05-01

    The article mainly focuses on the enrichment of the output power obatined from Spin torque nano-oscillator by introducing the heterogeneous structure in multilayer nanopillar device. Here we devised two homogeneous and two heterogeneous devices having NiFe and Co materials. The dynamics of the devices are governed by a famous Landu- Lifshitz -Gilbert-Solencskwei (LLGS) equation which can be solved numerically usin embedded RK-4 procedure. The current density and the external magnetic field for four devices are taken as 5×l011A/m2 and 6×l0-3 A/m respectively. The applied dc current is converted into spin polarized dc current while it passes through pinned layer. The generated spin polarized dc currents produces spin transfer torque with the free layer magnetization via spacer. Thus the magnetization of the free layer gets a sustained oscillaton. The results obtained from the heterogeneous STNOs are really fascinating. The frequency of the NiFe/ Cu/NiFe and Co/Cu/NiFe devices have the same frequency but there is a tremendous change in the output power which is exactly twice that the NiFe/Cu/NiFe device. The similar behaviour is also obtained from Co/Cu/Co and NiFe/Cu/Co devices. The line width and the Q-factor of the output microwave signal are also computed. Among the four devices, the NiFe/Cu/Co heterogeneous device has low linewidth (408 MHz) and high Q-factor (4.77).

  10. Amalgam Surface Treatment by Different Output Powers of Er:YAG Laser:SEM Evaluation

    PubMed Central

    Hosseini, Mohammad Hashem; Hassanpour, Mehdi; Etemadi, Ardavan; Ranjbar Omrani, Ladan; Darvishpour, Hojat; Chiniforush, Nasim

    2015-01-01

    Introduction: The purpose of this study was to evaluate amalgam surfaces treated by different output powers of erbium-doped yttrium aluminum garnet (Er:YAG) laser by scanning electron microscope (SEM). Methods: Twenty-one amalgam blocks (8 mm × 8 mm, 3 mm thickness) were prepared by condensing silver amalgam (into putty impression material. After keeping them for 24 hours in distilled water, they were divided into 7 groups as follow: G1: Er:YAG laser (1 W, 50 mJ), G2: Er:YAG laser (2 W, 100 mJ), G3: Er:YAG laser (3 W, 150 mJ), G4: Sandblast, G5: Sandblast + Er:YAG laser (1 W, 50 mJ), G6: Sandblast +Er:YAG laser (2 W, 100 mJ) and G7: Sandblast +Er:YAG laser (3 W, 150 mJ). Then after preparation of all samples, they were examined by SEM. Results: The SEM results of amalgam surfaces treated by different output powers of Er:YAG laser showed some pitting areas with non-homogenous irregularities Conclusion: It seems that the application of sandblasting accompanied by Er:YAG laser irradiation can provide proper surface for bonding of orthodontic brackets. PMID:26705463

  11. Probabilistic Physics-Based Risk Tools Used to Analyze the International Space Station Electrical Power System Output

    NASA Technical Reports Server (NTRS)

    Patel, Bhogila M.; Hoge, Peter A.; Nagpal, Vinod K.; Hojnicki, Jeffrey S.; Rusick, Jeffrey J.

    2004-01-01

    This paper describes the methods employed to apply probabilistic modeling techniques to the International Space Station (ISS) power system. These techniques were used to quantify the probabilistic variation in the power output, also called the response variable, due to variations (uncertainties) associated with knowledge of the influencing factors called the random variables. These uncertainties can be due to unknown environmental conditions, variation in the performance of electrical power system components or sensor tolerances. Uncertainties in these variables, cause corresponding variations in the power output, but the magnitude of that effect varies with the ISS operating conditions, e.g. whether or not the solar panels are actively tracking the sun. Therefore, it is important to quantify the influence of these uncertainties on the power output for optimizing the power available for experiments.

  12. Enhancement of the output power of terahertz folded waveguide oscillator by two parallel electron beams

    SciTech Connect

    Li, Ke Cao, Miaomiao; Liu, Wenxin Wang, Yong; Liao, Suying

    2015-11-15

    A novel two-beam folded waveguide (FW) oscillator is presented for the purpose of gaining higher power with a small-size circuit compared with the normal FW oscillator. The high-frequency characteristics of the two-beam FW, including dispersion and interaction impedance, were investigated by the numerical simulation and compared with the one-beam FW. The radio-frequency loss of the two-beam FW was also analyzed. A 3-D particle-in-cell code CHIPIC was applied to analyze and optimize the performance of a G-band two-beam FW oscillator. The influences of the distance between the two beam tunnels, beam voltage, the number of periods, magnetic field, radius of beam tunnel, and the packing ratio on the circuit performance are investigated in detail. Compared with a one-beam circuit, a larger output power of the two-beam circuit with the same beam power was observed by the simulation. Moreover, the start-oscillation current of two-beam circuit is much lower than the one-beam circuit with better performance. It will favor the miniaturized design of the high-power terahertz oscillator.

  13. Optimization of the output and efficiency of a high power cascaded arc hydrogen plasma source

    SciTech Connect

    Vijvers, W. A. J.; Gils, C. A. J. van; Goedheer, W. J.; Meiden, H. J. van der; Veremiyenko, V. P.; Westerhout, J.; Lopes Cardozo, N. J.; Rooij, G. J. van; Schram, D. C.

    2008-09-15

    The operation of a cascaded arc hydrogen plasma source was experimentally investigated to provide an empirical basis for the scaling of this source to higher plasma fluxes and efficiencies. The flux and efficiency were determined as a function of the input power, discharge channel diameter, and hydrogen gas flow rate. Measurements of the pressure in the arc channel show that the flow is well described by Poiseuille flow and that the effective heavy particle temperature is approximately 0.8 eV. Interpretation of the measured I-V data in terms of a one-parameter model shows that the plasma production is proportional to the input power, to the square root of the hydrogen flow rate, and is independent of the channel diameter. The observed scaling shows that the dominant power loss mechanism inside the arc channel is one that scales with the effective volume of the plasma in the discharge channel. Measurements on the plasma output with Thomson scattering confirm the linear dependence of the plasma production on the input power. Extrapolation of these results shows that (without a magnetic field) an improvement in the plasma production by a factor of 10 over where it was in van Rooij et al. [Appl. Phys. Lett. 90, 121501 (2007)] should be possible.

  14. Quantum cascade laser in a master oscillator power amplifier configuration with Watt-level optical output power.

    PubMed

    Hinkov, Borislav; Beck, Mattias; Gini, Emilio; Faist, Jérôme

    2013-08-12

    We present the design and realization of short-wavelength (λ = 4.53 μm) and buried-heterostructure quantum cascade lasers in a master oscillator power amplifier configuration. Watt-level, singlemode peak optical output power is demonstrated for typical non-tapered 4 μm wide and 5.25 mm long devices. Farfield measurements prove a symmetric, single transverse-mode emission in TM(00)-mode with typical divergences of 25° and 27° in and perpendicular to growth direction, respectively. We demonstrate singlemode tuning over a range of 7.9 cm(-1) for temperatures between 263K and 313K and also singlemode emission for different driving currents. The side mode suppression ratio is measured to be higher than 20 dB. PMID:23938833

  15. An Evaluation of the Additional Acoustic Power Needed to Overcome the Effects of a Test-Articles Absorption During Reverberant Chamber Acoustic Testing of Spaceflight Hardware

    NASA Technical Reports Server (NTRS)

    Hozman, Aron D.; Hughes, William O.

    2014-01-01

    It is important to realize that some test-articles may have significant sound absorption that may challenge the acoustic power capabilities of a test facility. Therefore, to mitigate this risk of not being able to meet the customers target spectrum, it is prudent to demonstrate early-on an increased acoustic power capability which compensates for this test-article absorption. This paper describes a concise method to reduce this risk when testing aerospace test-articles which have significant absorption. This method was successfully applied during the SpaceX Falcon 9 Payload Fairing acoustic test program at the NASA Glenn Research Center Plum Brook Stations RATF.

  16. The effect of low-level laser irradiation on dog spermatozoa motility is dependent on laser output power.

    PubMed

    Corral-Baqués, M I; Rivera, M M; Rigau, T; Rodríguez-Gil, J E; Rigau, J

    2009-09-01

    Biological tissues respond to low-level laser irradiation and so do dog spermatozoa. Among the main parameters to be considered when a biological tissue is irradiated is the output power. We have studied the effects on sperm motility of 655 nm continuous wave diode laser irradiation at different output powers with 3.34 J (5.97 J/cm(2)). The second fraction of fresh dog sperm was divided into five groups: control, and four to be irradiated with an average output power of 6.8 mW, 15.4 mW, 33.1 mW and 49.7 mW, respectively. At 0 min and 45 min after irradiation, pictures were taken and a computer aided sperm analysis (CASA) performed to analyse different motility parameters. The results showed that different output powers affected dog semen motility parameters differently. The highest output power showed the most intense effects. Significant changes in the structure of the motile sperm subpopulation were linked to the different output powers used.

  17. Flexible, transparent and exceptionally high power output nanogenerators based on ultrathin ZnO nanoflakes

    NASA Astrophysics Data System (ADS)

    van Ngoc, Huynh; Kang, Dae Joon

    2016-02-01

    Novel nanogenerator structures composed of ZnO nanoflakes of less than 10 nm thickness were fabricated using a novel method involving a facile synthetic route and a rational design. The fabricated nanogenerators exhibited a short-circuit current density of 67 μA cm-2, a peak-to-peak open-circuit voltage of 110 V, and an overall output power density exceeding 1.2 mW cm-2, and to the best of our knowledge, these are the best values that have been reported so far in the literature on ZnO-based nanogenerators. We demonstrated that our nanogenerator design could instantaneously power 20 commercial green light-emitting diodes without any additional energy storage processes. Both the facile synthetic route for the ZnO nanoflakes and the straightforward device fabrication process present great scaling potential in order to power mobile and personal electronics that can be used in smart wearable systems, transparent and flexible devices, implantable telemetric energy receivers, electronic emergency equipment, and other self-powered nano/micro devices.Novel nanogenerator structures composed of ZnO nanoflakes of less than 10 nm thickness were fabricated using a novel method involving a facile synthetic route and a rational design. The fabricated nanogenerators exhibited a short-circuit current density of 67 μA cm-2, a peak-to-peak open-circuit voltage of 110 V, and an overall output power density exceeding 1.2 mW cm-2, and to the best of our knowledge, these are the best values that have been reported so far in the literature on ZnO-based nanogenerators. We demonstrated that our nanogenerator design could instantaneously power 20 commercial green light-emitting diodes without any additional energy storage processes. Both the facile synthetic route for the ZnO nanoflakes and the straightforward device fabrication process present great scaling potential in order to power mobile and personal electronics that can be used in smart wearable systems, transparent and flexible

  18. Ergometer error and biological variation in power output in a performance test with three cycle ergometers.

    PubMed

    Paton, C D; Hopkins, W G

    2006-06-01

    When physical performance is monitored with an ergometer, random error arising from the ergometer combines with biological variation from the subject to limit the precision of estimation of performance changes. We report here the contributions of ergometer error and biological variation to the error of measurement in a performance test with two popular cycle ergometers (air-braked Kingcycle, mobile SRM crankset) and a relatively new inexpensive mobile ergometer (PowerTap hub). Eleven well-trained male cyclists performed a familiarization trial followed by three 5-min time trials within 2 wk on a racing cycle fitted with the SRM and PowerTap and mounted on the Kingcycle. Mean power output in each trial was recorded with all ergometers simultaneously. A novel analysis using mixed modelling of log-transformed mean power provided estimates of the standard error of measurement as a coefficient of variation and its components arising from the ergometer and the cyclists. The usual errors of measurement were: Kingcycle 2.2 %, PowerTap 1.5 %, and SRM 1.6 % (90 % confidence limits +/- 1.3). The components of these errors arising purely from the ergometers and the cyclists were: Kingcycle 1.8 %, PowerTap 0.9 %, SRM 1.1 %, and cyclists 1.2 % (+/- 1.5). Thus, ergometer errors and biological variation made substantial contributions to the usual error of measurement. Use of the best ergometers and of test protocols that reduce biological variation would improve monitoring of the small changes that matter to elite athletes.

  19. Loss of power output and laser fibre degradation during 120 watt lithium-triborate HPS laser vaporisation of the prostate

    NASA Astrophysics Data System (ADS)

    Hermanns, Thomas; Sulser, Tullio; Hefermehl, Lukas J.; Strebel, Daniel; Michel, Maurice-Stephan; Müntener, Michael; Meier, Alexander H.; Seifert, Hans-Helge

    2009-02-01

    It has recently been shown that laser fibre deterioration leads to a significant decrease of power output during 80 W potassium titanyl phosphate (KTP) laser vaporisation (LV) of the prostate. This decrease results in inefficient vaporisation especially towards the end of the procedure. For the new 120 W lithium-triborate (LBO) High Performance System (HPS) laser not only higher power but also changes in beam characteristics and improved fibre quality have been advertised. However, high laser power has been identified as a risk factor for laser fibre degradation. Between July and September 2008 25 laser fibres were investigated during routine 120 W LBO-LV in 20 consecutive patients. Laser beam power was measured at baseline and after the application of every 25 kJ during the LV procedure. Postoperatively, the surgeon subjectively rated the performance of the respective fibre on a scale from 1 to 4 (1 indicating perfect and 4 insufficient performance). Additionally, microscopic examination of the fibre tip was performed. Median energy applied was 212 kJ. Changes of power output were similar for all fibres. Typically, a steep decrease of power output within the first 50 kJ was followed by a continuous mild decrease until the end of the procedure. After the application of 50 kJ the median power output was 63% (58-73% interquartile range) of the baseline value. The median power output at the end of the 275 kJ-lifespan of the fibres was 42% (40-47%). The median surgeons' rating of the overall performance of the laser fibres was 2 and the median estimated final decrease of power output 60%. Some degree of degradation at the emission window was microscopically detectable in all cases after the procedure. However, even after the application of 275 kJ, these structural changes were only moderate. Minor degradation of the laser fibre was associated with a significant decrease of power output during 120 W LBO-LV. However, following an early, steep decrease, power output

  20. Recovery of power output and heart rate kinetics during repeated bouts of rowing exercise with different rest intervals.

    PubMed

    Mavrommataki, Evangelia; Bogdanis, Gregory C; Kaloupsis, Socrates; Maridaki, Maria

    2006-01-01

    This study examined the effect of recovery time on the maintenance of power output and the heart rate response during repeated maximal rowing exercise. Nine male, junior rowers (age: 16 ± 1 years; body mass: 74.0 ± 9.1 kg; height: 1.78 ± 0.03 m) performed two consecutive all-out 1000 m bouts on a rowing ergometer on three separate occasions. The rest interval between the two bouts was 1.5 (INT1.5), 3 (INT3) and 6 min (INT6), allocated in random order. Power output was averaged for each 1000 m bout and for the first and last 500 m of each bout. Heart rate kinetics were determined using a two-component exponential model. Performance time and mean power output for the first bout was 209 ± 3 s and 313 ± 10 W respectively. Recovery of mean power output was incomplete even after 6 min (78 ± 2, 81 ± 2 and 84 ± 2 % for INT1.5, INT3 and INT6 respectively). Mean power output after INT6 was higher (p < 0.01) only compared with INT1.5. Power output during the first 500 m of bout 2 after INT6 was 10% higher compared with the second 500 m. During INT1.5 and INT3 power output during the first and the second 500 m of bout 2 was similar. Peak heart rate (~197 b·min(-1)) and the HR time constant (~13 s) were unaffected by prior exercise and recovery time. However, when the recovery was short (INT1.5), HR during the first 50 s of bout 2 was significantly higher compared with corresponding values during bout 1. The present study has shown that in order to maintain similar power outputs during repeated maximal rowing exercise, the recovery interval must be greater than 6 min. The influence of a longer recovery time (INT6) on maintenance of power output was only evident during the first half of the second 1000 m bout. Key PointsThe recovery of mean power output during two repeated maximal 1000 m bouts of rowing exercise was incomplete even after a 6 min rest interval.The benefit of the longer rest interval was apparent only during the first 500 m of bout 2.The HR time constant

  1. Possible factors determining the non-linearity in the VO2-power output relationship in humans: theoretical studies.

    PubMed

    Korzeniewski, Bernard; Zoladz, Jerzy A

    2003-08-01

    At low power output exercise (below lactate threshold), the oxygen uptake increases linearly with power output, but at high power output exercise (above lactate threshold) some additional oxygen consumption causes a non-linearity in the overall VO(2) (oxygen uptake rate)-power output relationship. The functional significance of this phenomenon for human exercise tolerance is very important, but the mechanisms underlying it remain unknown. In the present work, a computer model of oxidative phosphorylation in intact skeletal muscle developed previously is used to examine the background of this relationship in different modes of exercise. Our simulations demonstrate that the non-linearity in the VO(2)-power output relationship and the difference in the magnitude of this non-linearity between incremental exercise mode and square-wave exercise mode (constant power output exercise) can be generated by introducing into the model some hypothetical factor F (group of associated factors) that accumulate(s) in time during exercise. The performed computer simulations, based on this assumption, give proper time courses of changes in VO(2) and [PCr] after an onset of work of different intensities, including the slow component in VO(2), well matching the experimental results. Moreover, if it is assumed that the exercise terminates because of fatigue when the amount/intensity of F exceed some threshold value, the model allows the generation of a proper shape of the well-known power-duration curve. This fact suggests that the phenomenon of the non-linearity of the VO(2)-power output relationship and the magnitude of this non-linearity in different modes of exercise is determined by some factor(s) responsible for muscle fatigue.

  2. Study on electrical power output of floating photovoltaic and conventional photovoltaic

    NASA Astrophysics Data System (ADS)

    Azmi, Mohd Syahriman Mohd; Othman, Mohd Yusof Hj.; Ruslan, Mohd Hafidz Hj.; Sopian, Kamaruzzaman; Majid, Zafri Azran Abdul

    2013-11-01

    In this paper, several attempt were made to investigate the best electrical performance of a floating photovoltaic (FPV). In photovoltaic (PV) system, the electrical efficiency of the system decreases rapidly as the PV module temperature increases. Therefore, in order to achieve higher electrical efficiency, the PV module have to be cooled by removing the heat in some way. This paper presents study on a conventional photovoltaic (PV) module and floating photovoltaic (FPV) system. The objective of the study is to compare the performance of conventional PV module and FPV. At FPV, an absorber comprises of aluminum flat-box housing was attached to the back of the PV module to absorb heat. Water is used to cool the PV module by passing it under the bottom surface of the module. The system was tested under simulated solar intensity of 417 W/m2, 667 W/m2 and 834 W/m2. Current (I) - voltage (V) curves and power (P) - voltage (V) curves of the results were analyzed. The study found that the FPV has higher efficiency and total power gain than the conventional PV module. The average PV temperature in a FPV might be lower than that for a conventional PV module, thereby increasing its electrical power output. The simplicity of the system structure and aluminum as the chosen material enabled it to reduce the installation costs for a larger scale. Applicable as heat sink, this FPV system is convenient to place on lakes, ponds or rivers.

  3. The Measurement of Maximal (Anaerobic) Power Output on a Cycle Ergometer: A Critical Review

    PubMed Central

    Driss, Tarak; Vandewalle, Henry

    2013-01-01

    The interests and limits of the different methods and protocols of maximal (anaerobic) power (Pmax) assessment are reviewed: single all-out tests versus force-velocity tests, isokinetic ergometers versus friction-loaded ergometers, measure of Pmax during the acceleration phase or at peak velocity. The effects of training, athletic practice, diet and pharmacological substances upon the production of maximal mechanical power are not discussed in this review mainly focused on the technical (ergometer, crank length, toe clips), methodological (protocols) and biological factors (muscle volume, muscle fiber type, age, gender, growth, temperature, chronobiology and fatigue) limiting Pmax in cycling. Although the validity of the Wingate test is questionable, a large part of the review is dedicated to this test which is currently the all-out cycling test the most often used. The biomechanical characteristics specific of maximal and high speed cycling, the bioenergetics of the all-out cycling exercises and the influence of biochemical factors (acidosis and alkalosis, phosphate ions…) are recalled at the beginning of the paper. The basic knowledge concerning the consequences of the force-velocity relationship upon power output, the biomechanics of sub-maximal cycling exercises and the study on the force-velocity relationship in cycling by Dickinson in 1928 are presented in Appendices. PMID:24073413

  4. Functional Capacity, Muscle Fat Infiltration, Power Output, and Cognitive Impairment in Institutionalized Frail Oldest Old

    PubMed Central

    Casas-Herrero, Alvaro; Cadore, Eduardo L.; Zambom-Ferraresi, Fabricio; Idoate, Fernando; Millor, Nora; Martínez-Ramirez, Alicia; Gómez, Marisol; Rodriguez-Mañas, Leocadio; Marcellán, Teresa; de Gordoa, Ana Ruiz; Marques, Mário C.

    2013-01-01

    Abstract This study examined the neuromuscular and functional performance differences between frail oldest old with and without mild cognitive impairment (MCI). In addition, the associations between functional capacities, muscle mass, strength, and power output of the leg muscles were also examined. Forty-three elderly men and women (91.9±4.1 years) were classified into three groups—the frail group, the frail with MCI group (frail+MCI), and the non-frail group. Strength tests were performed for upper and lower limbs. Functional tests included 5-meter habitual gait, timed up-and-go (TUG), dual task performance, balance, and rise from a chair ability. Incidence of falls was assessed using questionnaires. The thigh muscle mass and attenuation were assessed using computed tomography. There were no differences between the frail and frail+MCI groups for all the functional variables analyzed, except in the cognitive score of the TUG with verbal task, which frail showed greater performance than the frail+MCI group. Significant associations were observed between the functional performance, incidence of falls, muscle mass, strength, and power in the frail and frail+MCI groups (r=−0.73 to r=0.83, p<0.01 to p<0.05). These results suggest that the frail oldest old with and without MCI have similar functional and neuromuscular outcomes. Furthermore, the functional outcomes and incidences of falls are associated with muscle mass, strength, and power in the frail elderly population. PMID:23822577

  5. The measurement of maximal (anaerobic) power output on a cycle ergometer: a critical review.

    PubMed

    Driss, Tarak; Vandewalle, Henry

    2013-01-01

    The interests and limits of the different methods and protocols of maximal (anaerobic) power (Pmax) assessment are reviewed: single all-out tests versus force-velocity tests, isokinetic ergometers versus friction-loaded ergometers, measure of Pmax during the acceleration phase or at peak velocity. The effects of training, athletic practice, diet and pharmacological substances upon the production of maximal mechanical power are not discussed in this review mainly focused on the technical (ergometer, crank length, toe clips), methodological (protocols) and biological factors (muscle volume, muscle fiber type, age, gender, growth, temperature, chronobiology and fatigue) limiting Pmax in cycling. Although the validity of the Wingate test is questionable, a large part of the review is dedicated to this test which is currently the all-out cycling test the most often used. The biomechanical characteristics specific of maximal and high speed cycling, the bioenergetics of the all-out cycling exercises and the influence of biochemical factors (acidosis and alkalosis, phosphate ions…) are recalled at the beginning of the paper. The basic knowledge concerning the consequences of the force-velocity relationship upon power output, the biomechanics of sub-maximal cycling exercises and the study on the force-velocity relationship in cycling by Dickinson in 1928 are presented in Appendices.

  6. Functional capacity, muscle fat infiltration, power output, and cognitive impairment in institutionalized frail oldest old.

    PubMed

    Casas-Herrero, Alvaro; Cadore, Eduardo L; Zambom-Ferraresi, Fabricio; Idoate, Fernando; Millor, Nora; Martínez-Ramirez, Alicia; Gómez, Marisol; Rodriguez-Mañas, Leocadio; Marcellán, Teresa; de Gordoa, Ana Ruiz; Marques, Mário C; Izquierdo, Mikel

    2013-10-01

    This study examined the neuromuscular and functional performance differences between frail oldest old with and without mild cognitive impairment (MCI). In addition, the associations between functional capacities, muscle mass, strength, and power output of the leg muscles were also examined. Forty-three elderly men and women (91.9±4.1 years) were classified into three groups--the frail group, the frail with MCI group (frail+MCI), and the non-frail group. Strength tests were performed for upper and lower limbs. Functional tests included 5-meter habitual gait, timed up-and-go (TUG), dual task performance, balance, and rise from a chair ability. Incidence of falls was assessed using questionnaires. The thigh muscle mass and attenuation were assessed using computed tomography. There were no differences between the frail and frail+MCI groups for all the functional variables analyzed, except in the cognitive score of the TUG with verbal task, which frail showed greater performance than the frail+MCI group. Significant associations were observed between the functional performance, incidence of falls, muscle mass, strength, and power in the frail and frail+MCI groups (r=-0.73 to r=0.83, p<0.01 to p<0.05). These results suggest that the frail oldest old with and without MCI have similar functional and neuromuscular outcomes. Furthermore, the functional outcomes and incidences of falls are associated with muscle mass, strength, and power in the frail elderly population.

  7. Suction power output and the inertial cost of rotating the neurocranium to generate suction in fish.

    PubMed

    Van Wassenbergh, Sam; Day, Steven W; Hernández, L Patricia; Higham, Timothy E; Skorczewski, Tyler

    2015-05-01

    To expand the buccal cavity, many suction-feeding fishes rely on a considerable contribution from dorsal rotation of the dorsal part of the head including the brains, eyes, and several bones forming the braincase and skull roof (jointly referred to as the neurocranium). As the neurocranium takes up a large part of the total mass of the head, this rotation may incur a considerable inertial cost. If so, this would suggest a significant selective pressure on the kinematics and mass distribution of the neurocranium of suction feeders. Here, an inverse dynamic model is formulated to calculate the instantaneous power required to rotate the neurocranium, approximated by a quarter ellipsoid volume of homogeneous density, as well as to calculate the instantaneous suction power based on intra-oral pressure and head volume quantifications. We applied this model to largemouth bass (Micropterus salmoides) and found that the power required to rotate the neurocranium accounts for only about 4% of the power required to suck water into the mouth. Furthermore, recovery of kinetic energy from the rotating neurocranium converted into suction work may be possible during the phase of neurocranial deceleration. Thus, we suggest that only a negligible proportion of the power output of the feeding muscles is lost as inertial costs in the largemouth bass. Consequently, the feeding performance of piscivorous suction feeders with generalised morphology, comparable to our model species, is not limited by neurocranial motion during head expansion. This suggests that it is thus not likely to be a factor of importance in the evolution of cranial shape and size. PMID:25769945

  8. Design of spherical electron gun for ultra high frequency, CW power inductive output tube

    NASA Astrophysics Data System (ADS)

    Kaushik, Meenu; Joshi, L. M.

    2016-03-01

    Inductive Output Tube (IOT) is an amplifier that usually operates in UHF range. It is an electron tube whose basic structure is similar to conventional vacuum devices. This device is widely used in broadcast applications but is now being explored for scientific applications also specifically, particle accelerators and fusion plasma heating purposes. The paper describes the design approach of a spherical gridded electron gun of a 500 MHz, 100 kW CW power IOT. The electron gun structure has been simulated and optimized for operating voltage and current of 40kV and 3.5 A respectively. The electromagnetic analysis of this spherical electron gun has been carried out in CST and TRAK codes.

  9. Efficiency at maximum power output of an irreversible Carnot-like cycle with internally dissipative friction.

    PubMed

    Wang, Jianhui; He, Jizhou

    2012-11-01

    We investigate the efficiency at the maximum power output (EMP) of an irreversible Carnot engine performing finite-time cycles between two reservoirs at constant temperatures T(h) and T(c) (

  10. A K-band GaAs FET amplifier with 8.2-W output power

    NASA Technical Reports Server (NTRS)

    Goel, J.

    1984-01-01

    An 8.2-W GaAs FET amplifier with 38.6 + or - 0.5-dB gain over a 17.7-19.1-GHz frequency band has been developed. This amplifier combines the outputs of eight multistage amplifier modules utilizing a radial combiner. This state-of-the art power level has been achieved with AM/PM of less than 2 deg/dB. The third-order intermodulation products at 1-dB gain compression were 20 dBc, and variation in group delay over the frequency band was less than + or - 0.25 ns. Tests show that the amplifier is unconditionally stable and follows the graceful-degradation principle.

  11. Synchronous Generator with HTS-2G field coils for Windmills with output power 1 MW

    NASA Astrophysics Data System (ADS)

    Kovalev, K.; Kovalev, L.; Poltavets, V.; Samsonovich, S.; Ilyasov, R.; Levin, A.; Surin, M.

    2014-05-01

    Nowadays synchronous generators for wind-mills are developed worldwide. The cost of the generator is determined by its size and weight. In this deal the implementation of HTS-2G generators is very perspective. The application of HTS 2G field coils in the rotor allows to reduce the size of the generator is 1.75 times. In this work the design 1 MW HTS-2G generator is considered. The designed 1 MW HTS-2G generator has the following parameters: rotor diameter 800 mm, active length 400 mm, phase voltage 690V, rotor speed 600 min-1 rotor field coils with HTS-2G tapes. HTS-2G field coils located in the rotating cryostat and cooled by liquid nitrogen. The simulation and optimization of HTS-2G field coils geometry allowed to increase feed DC current up to 50A. Copper stator windings are water cooled. Magnetic and electrical losses in 1 MW HTS-2G generator do not exceed 1.6% of the nominal output power. In the construction of HTS-2G generator the wave multiplier with ratio 1:40 is used. The latter allows to reduce the total mass of HTS-2G generator down to 1.5 tons. The small-scale model of HTS-2G generator with output power 50 kW was designed, manufactured and tested. The test results showed good agreement with calculation results. The manufacturing of 1 MW HTS-2G generator is planned in 2014. This work is done under support of Rosatom within the frames of Russian Project "Superconducting Industry".

  12. Bandwidth-efficient frequency-domain equalization for single carrier multiple-input multiple-output underwater acoustic communications.

    PubMed

    Zhang, Jian; Zheng, Yahong Rosa

    2010-11-01

    This paper proposes a single carrier (SC) receiver scheme with bandwidth-efficient frequency-domain equalization (FDE) for underwater acoustic (UWA) communications employing multiple transducers and multiple hydrophones. Different from the FDE methods that perform FDE on a whole data block, the proposed algorithm implements an overlapped-window FDE by partitioning a large block into small subblocks. A decision-directed channel estimation scheme is incorporated with the overlapped-window FDE to track channel variations and improve the error performance. The proposed algorithm significantly increases the length of each block and keeps the same number of training symbols per block, hence achieving better data efficiency without performance degradation. The proposed scheme is tested by the undersea data collected in the Rescheduled Acoustic Communications Experiment (RACE) in March 2008. Without coding, the 2-by-12 MIMO overlapped-window FDE reduces the average bit error rate (BER) over traditional SC-FDE schemes by 74.4% and 84.6% for the 400 m and 1000 m range systems, respectively, at the same data efficiency. If the same BER performance is required, the proposed algorithm has only 8.4% transmission overhead, comparing to over 20% overhead in other existing UWA OFDM and SC-FDE systems. The improved data efficiency and/or error performance of the proposed FDE scheme is achieved by slightly increased computational complexity over traditional SC-FDE schemes.

  13. Bifacial dye-sensitized solar cells with enhanced rear efficiency and power output

    NASA Astrophysics Data System (ADS)

    Cai, Hongyuan; Tang, Qunwei; He, Benlin; Li, Ru; Yu, Liangmin

    2014-11-01

    Pursuing a high power conversion efficiency with no sacrifice of cost-effectiveness has been a persistent objective for dye-sensitized solar cells (DSSCs). One promising solution to this impasse is increased light harvesting. Previous efforts in light harvesting have been made on setting blocking layers or reflecting layers, or adding a light harvester, resulting in tedious procedures without reducing the expenses. We present a mild solution strategy for synthesizing transparent Ru-Se alloy counter electrodes (CEs) for bifacial DSSC applications, displaying optimal front and rear efficiencies of 8.76% and 5.90%, respectively. In comparison with pristine Pt-based solar cells, the maximum power output has also been markedly enhanced. Moreover, fast start-up, high multiple start capability, and good stability are observed in the bifacial DSSCs with transparent Ru-Se binary alloy electrodes. The impressive efficiencies along with simple preparation of the cost-effective Ru-Se alloy CEs demonstrates their potential application in robust DSSCs.Pursuing a high power conversion efficiency with no sacrifice of cost-effectiveness has been a persistent objective for dye-sensitized solar cells (DSSCs). One promising solution to this impasse is increased light harvesting. Previous efforts in light harvesting have been made on setting blocking layers or reflecting layers, or adding a light harvester, resulting in tedious procedures without reducing the expenses. We present a mild solution strategy for synthesizing transparent Ru-Se alloy counter electrodes (CEs) for bifacial DSSC applications, displaying optimal front and rear efficiencies of 8.76% and 5.90%, respectively. In comparison with pristine Pt-based solar cells, the maximum power output has also been markedly enhanced. Moreover, fast start-up, high multiple start capability, and good stability are observed in the bifacial DSSCs with transparent Ru-Se binary alloy electrodes. The impressive efficiencies along with

  14. Vibration exercise as a warm-up modality for deadlift power output.

    PubMed

    Cochrane, Darryl J; Coley, Karl W; Pritchard, Hayden J; Barnes, Matthew J

    2015-04-01

    Vibration exercise (VbX) has gained popularity as a warm-up modality to enhance performance in golf, baseball, and sprint cycling, but little is known about the efficacy of using VbX as a warm-up before resistance exercise, such as deadlifting. The aim of this study was to compare the effects of a deadlift (DL)-specific warm-up, VbX warm-up, and Control on DL power output (PO). The DL warm-up (DL-WU) included 10, 8, and 5 repetitions performed at 30, 40, and 50% 1-repetition maximum (1RM), respectively, where the number of repetitions was matched by body-weight squats performed with vibration and without vibration (Control). The warm-up conditions were randomized and performed at least 2 days apart. Peak power (PP), mean power, rate of force development (RFD), and electromyography (EMG) were measured during the concentric phase of 2 consecutive DLs (75% 1RM) at 30 seconds and 2:30 minutes after the warm-up conditions. There was no significant (p > 0.05) main effect or interaction effect between the DL-WU, VbX warm-up, and Control for PP, mean power, RFD, and EMG. Vibration exercise warm-up did not exhibit an ergogenic effect to potentiate muscle activity more than the specific DL-WU and Control. Therefore, DL PO is affected to a similar extent, irrespective of the type of stimuli, when the warm-up is not focused on raising muscle temperature. PMID:25353078

  15. Vibration exercise as a warm-up modality for deadlift power output.

    PubMed

    Cochrane, Darryl J; Coley, Karl W; Pritchard, Hayden J; Barnes, Matthew J

    2015-04-01

    Vibration exercise (VbX) has gained popularity as a warm-up modality to enhance performance in golf, baseball, and sprint cycling, but little is known about the efficacy of using VbX as a warm-up before resistance exercise, such as deadlifting. The aim of this study was to compare the effects of a deadlift (DL)-specific warm-up, VbX warm-up, and Control on DL power output (PO). The DL warm-up (DL-WU) included 10, 8, and 5 repetitions performed at 30, 40, and 50% 1-repetition maximum (1RM), respectively, where the number of repetitions was matched by body-weight squats performed with vibration and without vibration (Control). The warm-up conditions were randomized and performed at least 2 days apart. Peak power (PP), mean power, rate of force development (RFD), and electromyography (EMG) were measured during the concentric phase of 2 consecutive DLs (75% 1RM) at 30 seconds and 2:30 minutes after the warm-up conditions. There was no significant (p > 0.05) main effect or interaction effect between the DL-WU, VbX warm-up, and Control for PP, mean power, RFD, and EMG. Vibration exercise warm-up did not exhibit an ergogenic effect to potentiate muscle activity more than the specific DL-WU and Control. Therefore, DL PO is affected to a similar extent, irrespective of the type of stimuli, when the warm-up is not focused on raising muscle temperature.

  16. Research on power-law acoustic transient signal detection based on wavelet transform

    NASA Astrophysics Data System (ADS)

    Han, Jian-hui; Yang, Ri-jie; Wang, Wei

    2007-11-01

    Aiming at the characteristics of acoustic transient signal emitted from antisubmarine weapon which is being dropped into water (torpedo, aerial sonobuoy and rocket assisted depth charge etc.), such as short duration, low SNR, abruptness and instability, based on traditional power-law detector, a new method to detect acoustic transient signal is proposed. Firstly wavelet transform is used to de-noise signal, removes random spectrum components and improves SNR. Then Power- Law detector is adopted to detect transient signal. The simulation results show the method can effectively extract envelop characteristic of transient signal on the condition of low SNR. The performance of WT-Power-Law markedly outgoes that of traditional Power-Law detection method.

  17. Bifacial dye-sensitized solar cells with enhanced rear efficiency and power output.

    PubMed

    Cai, Hongyuan; Tang, Qunwei; He, Benlin; Li, Ru; Yu, Liangmin

    2014-12-21

    Pursuing a high power conversion efficiency with no sacrifice of cost-effectiveness has been a persistent objective for dye-sensitized solar cells (DSSCs). One promising solution to this impasse is increased light harvesting. Previous efforts in light harvesting have been made on setting blocking layers or reflecting layers, or adding a light harvester, resulting in tedious procedures without reducing the expenses. We present a mild solution strategy for synthesizing transparent Ru-Se alloy counter electrodes (CEs) for bifacial DSSC applications, displaying optimal front and rear efficiencies of 8.76% and 5.90%, respectively. In comparison with pristine Pt-based solar cells, the maximum power output has also been markedly enhanced. Moreover, fast start-up, high multiple start capability, and good stability are observed in the bifacial DSSCs with transparent Ru-Se binary alloy electrodes. The impressive efficiencies along with simple preparation of the cost-effective Ru-Se alloy CEs demonstrates their potential application in robust DSSCs.

  18. Wind tunnel measurements of the power output variability and unsteady loading in a micro wind farm model

    NASA Astrophysics Data System (ADS)

    Bossuyt, Juliaan; Howland, Michael; Meneveau, Charles; Meyers, Johan

    2015-11-01

    To optimize wind farm layouts for a maximum power output and wind turbine lifetime, mean power output measurements in wind tunnel studies are not sufficient. Instead, detailed temporal information about the power output and unsteady loading from every single wind turbine in the wind farm is needed. A very small porous disc model with a realistic thrust coefficient of 0.75 - 0.85, was designed. The model is instrumented with a strain gage, allowing measurements of the thrust force, incoming velocity and power output with a frequency response up to the natural frequency of the model. This is shown by reproducing the -5/3 spectrum from the incoming flow. Thanks to its small size and compact instrumentation, the model allows wind tunnel studies of large wind turbine arrays with detailed temporal information from every wind turbine. Translating to field conditions with a length-scale ratio of 1:3,000 the frequencies studied from the data reach from 10-4 Hz up to about 6 .10-2 Hz. The model's capabilities are demonstrated with a large wind farm measurement consisting of close to 100 instrumented models. A high correlation is found between the power outputs of stream wise aligned wind turbines, which is in good agreement with results from prior LES simulations. Work supported by ERC (ActiveWindFarms, grant no. 306471) and by NSF (grants CBET-113380 and IIA-1243482, the WINDINSPIRE project).

  19. Towards high power output of scaled-up benthic microbial fuel cells (BMFCs) using multiple electron collectors.

    PubMed

    Liu, Bingchuan; Williams, Isaiah; Li, Yan; Wang, Lei; Bagtzoglou, Amvrossios; McCutcheon, Jeffrey; Li, Baikun

    2016-05-15

    This study aimed at achieving high power output of benthic microbial fuel cells (BMFCs) with novel geometric anode setups (inverted tube granular activated charcoal (IT-GAC) and carbon cloth roll (CCR)) and multiple anodes/electron collectors. The lab-scale tests showed the power density of IT-GAC and CCR anodes achieved at 2.92 and 2.55 W m(-2), the highest value ever reported in BMFCs. The power density of BMFCs substantially increased with electron collector number (titanium rods) in anodes. The connection of multiple electron collectors with multiple cathodes had much higher total voltage/current output than that with single cathode. The possibility of maintaining high power density at scaled-up BMFCs was explored by arranging multiple anodes in sediment. The compact configuration of multiple CCR anodes contacting each other did not deteriorate the performance of individual anodes, showing the feasibility of maximizing anode numbers per sediment footprint and achieving high power output. Multiple IT-GAC and CCR anodes with multiple collectors effectively utilized sediment at both horizontal and vertical directions and enhanced electron collection efficiency. This study demonstrated that bacterial adhesion and electron collection should be optimized on small anodes in order to maintain high power density and achieve high power output in the scaled-up BMFCs. PMID:26745789

  20. Catastrophic optical degradation of the output facet of high-power single-transverse-mode diode lasers. 1. Physical model

    SciTech Connect

    Miftakhutdinov, D R; Bogatov, Alexandr P; Drakin, A E

    2010-09-10

    The physical model of catastrophic optical degradation (COD) of the output facet of high-power single- transverse-mode diode lasers is developed. The model excels other models both in completeness of the physical analysis of the processes leading to COD and in allowance for design feature of lasers used to increase the COD threshold - protective coating of the output facet and current limitations near it. (lasers)

  1. Comparison of Comet Enflow and VA One Acoustic-to-Structure Power Flow Predictions

    NASA Technical Reports Server (NTRS)

    Grosveld, Ferdinand W.; Schiller, Noah H.; Cabell, Randolph H.

    2010-01-01

    Comet Enflow is a commercially available, high frequency vibroacoustic analysis software based on the Energy Finite Element Analysis (EFEA). In this method the same finite element mesh used for structural and acoustic analysis can be employed for the high frequency solutions. Comet Enflow is being validated for a floor-equipped composite cylinder by comparing the EFEA vibroacoustic response predictions with Statistical Energy Analysis (SEA) results from the commercial software program VA One from ESI Group. Early in this program a number of discrepancies became apparent in the Enflow predicted response for the power flow from an acoustic space to a structural subsystem. The power flow anomalies were studied for a simple cubic, a rectangular and a cylindrical structural model connected to an acoustic cavity. The current investigation focuses on three specific discrepancies between the Comet Enflow and the VA One predictions: the Enflow power transmission coefficient relative to the VA One coupling loss factor; the importance of the accuracy of the acoustic modal density formulation used within Enflow; and the recommended use of fast solvers in Comet Enflow. The frequency region of interest for this study covers the one-third octave bands with center frequencies from 16 Hz to 4000 Hz.

  2. Multicomponent exercises including muscle power training enhance muscle mass, power output, and functional outcomes in institutionalized frail nonagenarians.

    PubMed

    Cadore, Eduardo L; Casas-Herrero, Alvaro; Zambom-Ferraresi, Fabricio; Idoate, Fernando; Millor, Nora; Gómez, Marisol; Rodriguez-Mañas, Leocadio; Izquierdo, Mikel

    2014-04-01

    This randomized controlled trial examined the effects of multicomponent training on muscle power output, muscle mass, and muscle tissue attenuation; the risk of falls; and functional outcomes in frail nonagenarians. Twenty-four elderly (91.9 ± 4.1 years old) were randomized into intervention or control group. The intervention group performed a twice-weekly, 12-week multicomponent exercise program composed of muscle power training (8-10 repetitions, 40-60 % of the one-repetition maximum) combined with balance and gait retraining. Strength and power tests were performed on the upper and lower limbs. Gait velocity was assessed using the 5-m habitual gait and the time-up-and-go (TUG) tests with and without dual-task performance. Balance was assessed using the FICSIT-4 tests. The ability to rise from a chair test was assessed, and data on the incidence and risk of falls were assessed using questionnaires. Functional status was assessed before measurements with the Barthel Index. Midthigh lower extremity muscle mass and muscle fat infiltration were assessed using computed tomography. The intervention group showed significantly improved TUG with single and dual tasks, rise from a chair and balance performance (P < 0.01), and a reduced incidence of falls. In addition, the intervention group showed enhanced muscle power and strength (P < 0.01). Moreover, there were significant increases in the total and high-density muscle cross-sectional area in the intervention group. The control group significantly reduced strength and functional outcomes. Routine multicomponent exercise intervention should be prescribed to nonagenarians because overall physical outcomes are improved in this population.

  3. Lowest of AC-DC power output for electrostrictive polymers energy harvesting systems

    NASA Astrophysics Data System (ADS)

    Meddad, Mounir; Eddiai, Adil; Hajjaji, Abdelowahed; Guyomar, Daniel; Belkhiat, Saad; Boughaleb, Yahia; Chérif, Aida

    2013-11-01

    Advances in technology led to the development of electronic circuits and sensors with extremely low electricity consumption. At the same time, structural health monitoring, technology and intelligent integrated systems created a need for wireless sensors in hard to reach places in aerospace vehicles and large civil engineering structures. Powering sensors with energy harvesters eliminates the need to replace batteries on a regular basis. Scientists have been forced to search for new power source that are able to harvested energy from their surrounding environment (sunlight, temperature gradients etc.). Electrostrictive polymer belonging to the family of electro-active polymers, offer unique properties for the electromechanical transducer technology has been of particular interest over the last few years in order to replace conventional techniques such as those based on piezoelectric or electromagnetic, these materials are highly attractive for their low-density, with large strain capability that can be as high as two orders of magnitude greater than the striction-limited, rigid and fragile electroactive ceramics. Electrostrictive polymers sensors respond to vibration with an ac output signal, one of the most important objectives of the electronic interface is to realize the required AC-DC conversion. The goal of this paper is to design an active, high efficiency power doubler converter for electrostrictive polymers exclusively uses a fraction of the harvested energy to supply its active devices. The simulation results show that it is possible to obtain a maximum efficiency of the AC-DC converter equal to 80%. Premiliminary experimental measurements were performed and the results obtained are in good agreement with simulations.

  4. Frequency-Preserved Acoustic Diode Model with High Forward-Power-Transmission Rate

    NASA Astrophysics Data System (ADS)

    Liu, Chang; Du, Zongliang; Sun, Zhi; Gao, Huajian; Guo, Xu

    2015-06-01

    The acoustic diode (AD) can provide brighter and clearer ultrasound images by eliminating acoustic disturbances caused by sound waves traveling in two directions at the same time and interfering with each other. Such an AD could give designers new flexibility in making ultrasonic sources like those used in medical imaging or nondestructive testing. However, current AD designs, based on nonlinear effects, only partially fill this role by converting sound to a new frequency and blocking any backward flow of the original frequency. In this work, an AD model that preserves the frequencies of acoustic waves and has a relatively high forward-power-transmission rate is proposed. Theoretical analysis indicates that the proposed AD has forward, reverse, and breakdown characteristics very similar to electrical diodes. The significant rectifying effect of the proposed AD is verified numerically through a one-dimensional example. Possible schemes for experimental realization of this model as well as more complex and efficient AD designs are also discussed.

  5. Effect of acoustic coupling on power-law flame acceleration in spherical confinement

    NASA Astrophysics Data System (ADS)

    Akkerman, V'yacheslav; Law, Chung K.

    2013-01-01

    A model describing acoustically-generated parametric instability in a spherical chamber is developed for quasi-one-dimensional, low-Mach number flames. We demonstrate how sound waves generated by a centrally-ignited, outwardly-propagating accelerating flamefront can be incorporated into an existing theory of self-similar flame acceleration in free space [V. Akkerman, C. K. Law, and V. Bychkov, "Self-similar accelerative propagation of expanding wrinkled flames and explosion triggering," Phys. Rev. E 83, 026305 (2011)], 10.1103/PhysRevE.83.026305. Being reflected from the chamber wall, flame-generated acoustics interact with the flamefront and the attendant hydrodynamic flamefront cellular instability. This in turn affects the subsequent flame morphology and propagation speed. It is shown that the acoustics modify the power-law flame acceleration, concomitantly facilitating or inhibiting the transition to detonation in confinement, which allows reconciliation of a discrepancy in experimental measurements of different groups.

  6. High brightness direct diode laser with kW output power

    NASA Astrophysics Data System (ADS)

    Fritsche, Haro; Kruschke, Bastian; Koch, Ralf; Ferrario, Fabio; Kern, Holger; Pahl, Ulrich; Pflueger, Silke; Gries, Wolfgang

    2014-03-01

    High power, high brightness diode lasers are beginning to challenge solid state lasers, i.e. disk and fiber lasers. The core technologies for brightness scaling of diode lasers are optical stacking and dense spectral combining (DSC), as well as improvements of the diode material. Diode lasers will have the lowest cost of ownership, highest efficiency and most compact design among all lasers. In our modular product design tens of single emitters are combined in a compact package and launched into a 200 μm fiber with 0.08 NA. Dense spectral combining enables power scaling from 80 W to kilowatts. Volume Bragg Gratings and dichroic filters yield high optical efficiencies of more than 80% at low cost. Each module emits up to 500 W with a beam quality of 5.5 mm*mrad and less than 20 nm linewidth. High speed switching power supplies are integrated into the module and rise times as short as 6 μs have been demonstrated. Fast control algorithms based on FPGA and embedded microcontroller ensure high wall plug efficiency with a unique control loop time of only 30 μs. Individual modules are spectrally combined to result in direct diode laser systems with kilowatts of output power at identical beam quality. For low loss fiber coupling a 200 μm fiber is used and the NA is limited to 0.08 corresponding to a beam quality of 7.5 mm*mrad. The controller architecture is fully scalable without sacrificing loop time. We leverage automated manufacturing for cost effective, high yield production. A precision robotic system handles and aligns the individual fast axis lenses and tracks all quality relevant data. Similar technologies are also deployed for dense spectral combining aligning the VBG and dichroic filters. Operating at wavelengths between 900 nm and 1100 nm, these systems are mainly used in cutting and welding, but the technology can also be adapted to other wavelength ranges, such as 793 nm and 1530 nm. Around 1.5 μm the diodes are already successfully used for resonant

  7. Effects of magnitude and frequency of variations in external power output on simulated cycling time-trial performance.

    PubMed

    Wells, Marc; Atkinson, Greg; Marwood, Simon

    2013-01-01

    Mechanical models of cycling time-trial performance have indicated adverse effects of variations in external power output on overall performance times. Nevertheless, the precise influences of the magnitude and number of these variations over different distances of time trial are unclear. A hypothetical cyclist (body mass 70 kg, bicycle mass 10 kg) was studied using a mathematical model of cycling, which included the effects of acceleration. Performance times were modelled over distances of 4-40 km, mean power outputs of 200-600 W, power variation amplitudes of 5-15% and variation frequencies of 2-32 per time-trial. Effects of a "fast-start" strategy were compared with those of a constant-power strategy. Varying power improved 4-km performance at all power outputs, with the greatest improvement being 0.90 s for ± 15% power variation. For distances of 16.1, 20 and 40 km, varying power by ± 15% increased times by 3.29, 4.46 and 10.43 s respectively, suggesting that in long-duration cycling in constant environmental conditions, cyclists should strive to reduce power variation to maximise performance. The novel finding of the present study is that these effects are augmented with increasing event distance, amplitude and period of variation. These two latter factors reflect a poor adherence to a constant speed.

  8. The Prognostic Value of Peak Cardiac Power Output in Chinese Patients with Chronic Heart Failure

    PubMed Central

    Ma, Wenlin; Gong, Zhu; Ni, Yi; Zhang, Xiaoyu; Xu, Wenjun; Jiang, Jinfa; Che, Lin; Xu, Jiahong; Yan, Wenwen; Zhou, Lin; Li, Guanghe; Zhang, Qiping; Wang, Lemin

    2016-01-01

    Background Cardiopulmonary exercise testing has been widely used to risk stratify patients with chronic heart failure (CHF). Peak oxygen consumption (peakVO2) was regarded as a powerful predictor of survival, as it is a surrogate for peak cardiac output (CO), which by most is considered the “true” measure of heart failure. Therefore, it is reasonable to hypothesize that CO is an even stronger predictor than peak VO2. The present study is aimed to investigate the prognostic value of peak cardiac power output (peak CPO) in comparison with peakVO2 in Chinese patients with CHF. Methods Participants provided written informed consent to participate in this study. Totally 129 patients with CHF underwent symptom-limited cardiopulmonary exercise testing (CPET), with mean age 59.1±11.4 years, 87.6% male, 57.4% ischemic etiology, body mass index (BMI) 24.7±3.7 kg/m2 and LVEF 38±9%. CO was measured using an inert gas rebreathing method. The primary endpoints are cardiac deaths. Results Over median 33.7-month follow-up, 19 cardiac deaths were reported. Among peak VO2,VE/VCO2 slope and Peak CPO, their area under ROC were 0.64, 0.67, 0.68, respectively (Ρ<0.05).The optimal thresholds for predicting cardiac deaths were peak VO2≤13.4 ml.kg-1.min-1, and VE/VCO2 slope≥39.3 and peak CPO≤ 1.1 respectively by ROC analysis. Finally, in patients with a peak VO2≤13.4 ml.kg-1.min-1 those with peak CPO>1.1W had better survival than those with peak CPO ≤ 1.1W. However, by multivariate analysis adjusted for age, sex, BMI, resting heart rate, LVMI, LVEF, Peak CPO was not an independent predictor of cardiac deaths (P> 0.05). Conclusions Peak CPO was not a predictor of cardiac death in Chinese CHF patients. PMID:26808510

  9. 16 W output power by high-efficient spectral beam combining of DBR-tapered diode lasers.

    PubMed

    Müller, André; Vijayakumar, Deepak; Jensen, Ole Bjarlin; Hasler, Karl-Heinz; Sumpf, Bernd; Erbert, Götz; Andersen, Peter E; Petersen, Paul Michael

    2011-01-17

    Up to 16 W output power has been obtained using spectral beam combining of two 1063 nm DBR-tapered diode lasers. Using a reflecting volume Bragg grating, a combining efficiency as high as 93.7% is achieved, resulting in a single beam with high spatial coherence. The result represents the highest output power achieved by spectral beam combining of two single element tapered diode lasers. Since spectral beam combining does not affect beam propagation parameters, M2-values of 1.8 (fast axis) and 3.3 (slow axis) match the M2-values of the laser with lowest spatial coherence. The principle of spectral beam combining used in our experiments can be expanded to combine more than two tapered diode lasers and hence it is expected that the output power may be increased even further in the future.

  10. Increasing the output power of single 808-nm laser diodes using diamond submounts produced by microwave plasma chemical vapour deposition

    SciTech Connect

    Ashkinazi, E E; Bezotosnyi, V V; Bondarev, Vadim Yu; Kovalenko, V I; Konov, Vitalii I; Krokhin, Oleg N; Oleshchenko, V A; Pevtsov, Valerii F; Popov, Yurii M; Popovich, A F; Ral'chenko, Viktor G; Cheshev, E A

    2012-11-30

    We have designed and fabricated submounts from synthetic diamond grown by microwave plasma chemical vapour deposition and developed an economical process for metallising such submounts. Laser diode chips having an 808-nm emission wavelength, 3-mm-long cavity and 130-mm-wide stripe contact were mounted on copper heat sinks with the use of diamond submounts differing in quality. The devices were tested for more than 150 h in continuous mode at an output power of 8 W on diamond with a thermal conductivity of 700 W m{sup -1} K{sup -1}, and no changes in their output power were detected. On diamond with a thermal conductivity of 1600 W m{sup -1} K{sup -1}, stable cw operation for 24 h at an output power of 12 W was demonstrated. (letters)

  11. Self-heating study of bulk acoustic wave resonators under high RF power.

    PubMed

    Ivira, Brice; Fillit, René-Yves; Ndagijimana, Fabien; Benech, Philippe; Parat, Guy; Ancey, Pascal

    2008-01-01

    The present work first provides an experimental technique to study self-heating of bulk acoustic wave (BAW) resonators under high RF power in the gigahertz range. This study is specially focused on film bulk acoustic wave resonators and solidly mounted resonators processed onto silicon wafers and designed for wireless systems. Precisely, the reflection coefficient of a one-port device is measured while up to several watts are applied and power leads to electrical drifts of impedances. In the following, we describe how absorbed power can be determined from the incident one in real time. Therefore, an infrared camera held over the radio frequency micro electromechanical system (RF-MEMS) surface with an exceptional spatial resolution reaching up to 2 microm/pixels gives accurate temperature mapping of resonators after emissivity correction. From theoretical point of view, accurate three-dimensional (3-D) structures for finite-element modeling analyses are carried out to know the best materials and architectures to use for enhancing power handling. In both experimental and theoretical investigations, comparison is made between film bulk acoustic wave resonators and solidly mounted resonators. Thus, the trend in term of material, architecture, and size of device for power application such as in transmission path of a transceiver is clearly identified. PMID:18334320

  12. Self-heating study of bulk acoustic wave resonators under high RF power.

    PubMed

    Ivira, Brice; Fillit, René-Yves; Ndagijimana, Fabien; Benech, Philippe; Parat, Guy; Ancey, Pascal

    2008-01-01

    The present work first provides an experimental technique to study self-heating of bulk acoustic wave (BAW) resonators under high RF power in the gigahertz range. This study is specially focused on film bulk acoustic wave resonators and solidly mounted resonators processed onto silicon wafers and designed for wireless systems. Precisely, the reflection coefficient of a one-port device is measured while up to several watts are applied and power leads to electrical drifts of impedances. In the following, we describe how absorbed power can be determined from the incident one in real time. Therefore, an infrared camera held over the radio frequency micro electromechanical system (RF-MEMS) surface with an exceptional spatial resolution reaching up to 2 microm/pixels gives accurate temperature mapping of resonators after emissivity correction. From theoretical point of view, accurate three-dimensional (3-D) structures for finite-element modeling analyses are carried out to know the best materials and architectures to use for enhancing power handling. In both experimental and theoretical investigations, comparison is made between film bulk acoustic wave resonators and solidly mounted resonators. Thus, the trend in term of material, architecture, and size of device for power application such as in transmission path of a transceiver is clearly identified.

  13. Peak oxygen uptake and maximal power output of Olympic wheelchair-dependent athletes.

    PubMed

    Veeger, H E; Hadj Yahmed, M; van der Woude, L H; Charpentier, P

    1991-10-01

    To extend the existing data base on the cardiovascular capacity of wheelchair-dependent athletes, a maximum wheelchair exercise test was conducted by 48 athletes (8 females and 40 males) on a motor driven treadmill. Athletes were selected on availability from the representatives of eight different disciplines. For 36 subjects maximal external power was calculated on the basis of a separate drag test. Maximal oxygen uptake (VO2max) for the male population was 2.23 l.min-1 (32.9 ml.kg-1.min-1). Subjects were divided into functional categories according to the International Stoke Mandeville Classification, with one nonambulatory, nonparaplegic group classified as "LA." The LA group displayed the highest values while the class IC tetraplegic showed the lowest performance level. Classified over sports disciplines, male track and field representatives showed the highest VO2max (2.86 l.min-1, 44.9 ml.kg-1.min-1) and target shooting athletes the lowest (1.32 l.min-1, 16.3 ml.kg-2.min-1). Maximal power output was on average 81.1 W for the male population and varied from 65.8 W for class II athletes to 92.2 W for class LA. Between sports values ranged from 96.8 W for basketball players to 48.2 W for the archery representative. These data are useful for setting standards for maximally attainable performance levels in relation to sport, functional classification, or sex and underline the capability of the wheelchair-dependent to improve cardiovascular fitness.

  14. Impact of heavy soiling on the power output of PV modules

    NASA Astrophysics Data System (ADS)

    Schill, Christian; Brachmann, Stefan; Heck, Markus; Weiss, Karl-Anders; Koehl, Michael

    2011-09-01

    Fraunhofer ISE is running a PV-module outdoor testing set-up on the Gran Canaria island, one of the Canary Island located west of Morroco in the Atlantic Ocean. The performance of the modules is assessed by IV-curve monitoring every 10 minutes. The electronic set-up of the monitoring system - consisting of individual electronic loads for each module which go into an MPP-tracking mode between the IV-measurements - will be described in detail. Soiling of the exposed modules happened because of building constructions nearby. We decided not to clean the modules, but the radiation sensors and recorded the decrease of the power output and the efficiency over time. The efficiency dropped to 20 % within 5 months before a heavy rain and subsequently the service personnel on site cleaned the modules. A smaller rain-fall in between washed the dust partly away and accumulated it at the lower part of the module, what could be concluded from the shape of the IV-curves, which were similar to partial shading by hot-spot-tests and by partial snow cover.

  15. Efficiency at maximum power output for an engine with a passive piston

    NASA Astrophysics Data System (ADS)

    Sano, Tomohiko G.; Hayakawa, Hisao

    2016-08-01

    Efficiency at maximum power (MP) output for an engine with a passive piston without mechanical controls between two reservoirs is studied theoretically. We enclose a hard core gas partitioned by a massive piston in a temperature-controlled container and analyze the efficiency at MP under a heating and cooling protocol without controlling the pressure acting on the piston from outside. We find the following three results: (i) The efficiency at MP for a dilute gas is close to the Chambadal-Novikov-Curzon-Ahlborn (CNCA) efficiency if we can ignore the sidewall friction and the loss of energy between a gas particle and the piston, while (ii) the efficiency for a moderately dense gas becomes smaller than the CNCA efficiency even when the temperature difference of the reservoirs is small. (iii) Introducing the Onsager matrix for an engine with a passive piston, we verify that the tight coupling condition for the matrix of the dilute gas is satisfied, while that of the moderately dense gas is not satisfied because of the inevitable heat leak. We confirm the validity of these results using the molecular dynamics simulation and introducing an effective mean-field-like model which we call the stochastic mean field model.

  16. Effect of different bicycle body positions on power output in aerobically trained females.

    PubMed

    Hubenig, Lindsay R; Game, Alex B; Kennedy, Michael D

    2011-10-01

    Aerodynamic bicycle positioning reduces drag but also reduces power output (PO) in males. The effect of aerodynamic bicycle positioning in trained endurance females is unknown. Eighteen females participants (VO2max 49.7 ± 6.3 ml · kg(-1) · min(-1)) all with competitive experience performed cycling trials at ventilatory threshold 1 and 2 (VT-1, VT-2) in both an aerodynamic and an upright position. There was a significant difference in PO between the aerodynamic and upright positions at VT-1 (152.7 ± 28.0 Watts and 159.7 ± 33.1 Watts, respectively) but not at VT-2 (191.2 ± 39.1 Watts and 192.4 ± 40.0 Watts, respectively). There were no significant differences in heart rate, oxygen consumption, or cadence between positions at either intensity. At both intensities the individual response was varied and no trends due to years of experience or background (triathlete or cyclist) explained this variability. Therefore, despite the significant mean difference in PO at VT-1, these results indicate that in trained females the effect of aerodynamic positioning is individual.

  17. 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. PMID:27485020

  18. High output power of differently cut Nd:MgO:LiTaO3 CW lasers

    NASA Astrophysics Data System (ADS)

    Sun, D. H.; Liu, S. D.; Wang, D. Z.; Sang, Y. H.; Kang, X. L.; Liu, H.; Bi, Y.; Yan, B. X.; He, J. L.; Wang, J. Y.

    2013-04-01

    A high-quality Nd3+ and Mg2+ co-doped LiTaO3 (Nd:MgO:LT) crystal was grown by the Czochralski method. The polarized absorption spectra and fluorescence spectra were studied, and the absorption cross section was calculated by Judd-Ofelt (J-O) theory. The laser performance with different sample cuts of the crystal was investigated for the first time, and it was found that Nd:MgO:LT crystal with different cutting directions (a and c) exhibits different laser properties. By optimizing a partial reflectivity mirror in the laser experimental setting, a high continuous wave output power of 3.58 W was obtained at 1092 and 1076 nm with an optical-to-optical conversion efficiency of 22.78% and slope efficiency of 26.06%. The results indicate that Nd:MgO:LT crystal is a promising candidate for the manufacture of Nd3+ doped periodically poled MgO:LiTaO3 crystal (Nd:PPMgOLT), which should have considerable applications in self-frequency doubling and optical parametric oscillation laser devices.

  19. A Study on Estimation of Average Power Output Fluctuation of Clustered Photovoltaic Power Generation Systems in Urban District of a Few km2

    NASA Astrophysics Data System (ADS)

    Kato, Takeyoshi; Suzuoki, Yasuo

    The fluctuation of the total power output of clustered PV systems would be smaller than that of single PV system because of the time difference in the power output fluctuation among PV systems at different locations. This effect, so called smoothing-effect, must be taken into account properly when the impact of clustered PV systems on electric power system is assessed. If the average power output of clustered PV systems can be estimated from the power output of single PV system, it is very useful and helpful for the impact assessment. In this study, we propose a simple method to estimate the total power output fluctuation of clustered PV systems. In the proposed method, a smoothing effect is assumed to be caused as a result of two factors, i.e. time difference of overhead clouds passing among PV systems and the random change in the size and/or shape of clouds. The first one is formulated as a low-pass filter, assuming that output fluctuation is transmitted to the same direction as the wind direction at the constant speed. The second one is taken into account by using a Fourier transform surrogate data. The parameters in the proposed method were selected, so that the estimated fluctuation can be similar with that of ensemble average fluctuation of data observed at 5 points used as a training data set. Then, by using the selected parameters, the fluctuation property was estimated for other data set. The results show that the proposed method is useful for estimating the total power output fluctuation of clustered PV systems.

  20. Design of Low-power Wake-up Circuits in Underwater Acoustic Communication

    NASA Astrophysics Data System (ADS)

    Cuixia, Zhang; Jiaxin, Wu; Yuanxuan, Li

    In underwater acoustic communication, the power consumption of the underwater communication equipments at harsh conditions of marine environment is an important problem. Under that scenario, we propose a design of low-power wake-up circuits based on SCM C8051F020 system. Compare to traditional wake-up circuits which directly judge the energy of received signals, our approach can greatly reduce the misjudgment caused by the environmental disturbance, and the performance of energy conservation is effective. The low-power wake-up circuits possess a promising application prospect in the long-distance wireless underwater communication.

  1. Single-mode master-oscillator power amplifier at 647  nm with more than 500 mW output power.

    PubMed

    Blume, G; Pohl, J; Feise, D; Jendrzejewski, M; Greiner, M; Ressel, P; Paschke, K

    2015-04-15

    Using an AlGaInP-based truncated tapered power amplifier, it was possible to boost the output power of a 647-nm distributed Bragg reflector laser from 50 mW to more than 500 mW. The light source has the potential to replace bulky Kr ion lasers still in use at this wavelength. PMID:25872066

  2. Evaluation of Acoustic Doppler Current Profiler to Measure Discharge at New York Power Authority's Niagara Power Project, Niagara Falls, New York

    USGS Publications Warehouse

    Zajd, Henry J.

    2007-01-01

    The need for accurate real-time discharge in the International Niagara River hydro power system requires reliable, accurate and reproducible data. The U.S. Geological Survey has been widely using Acoustic Doppler Current Profilers (ADCP) to accurately measure discharge in riverine channels since the mid-1990s. The use of the ADCP to measure discharge has remained largely untested at hydroelectric-generation facilities such as the New York Power Authority's (NYPA) Niagara Power Project in Niagara Falls, N.Y. This facility has a large, engineered diversion channel with the capacity of high volume discharges in excess of 100,000 cubic feet per second (ft3/s). Facilities such as this could benefit from the use of an ADCP, if the ADCP discharge measurements prove to be more time effective and accurate than those obtained from the flow-calculation techniques that are currently used. Measurements of diversion flow by an ADCP in the 'Pant Leg' diversion channel at the Niagara Power Project were made on November 6, 7, and 8, 2006, and compared favorably (within 1 percent) with those obtained concurrently by a conventional Price-AA current-meter measurement during one of the ADCP measurement sessions. The mean discharge recorded during each 2-hour individual ADCP measurement session compared favorably with (3.5 to 6.8 percent greater than) the discharge values computed by the flow-calculation method presently in use by NYPA. The use of ADCP technology to measure discharge could ultimately permit increased power-generation efficiency at the NYPA Niagara Falls Power Project by providing improved predictions of the amount of water (and thus the power output) available.

  3. Acoustic tooth cleaner

    NASA Technical Reports Server (NTRS)

    Heyman, J. S. (Inventor)

    1982-01-01

    An acoustic oral hygiene unit is described that uses acoustic energy to oscillate mild abrasive particles in a water suspension which is then directed in a low pressure stream onto the teeth. The oscillating abrasives scrub the teeth clean removing food particles, plaque, calculous, and other foreign material from tooth surfaces, interproximal areas, and tooth-gingiva interface more effectively than any previous technique. The relatively low power output and the basic design makes the invention safe and convenient for everyday use in the home without special training. This invention replaces all former means of home dental prophylaxis, and requires no augmentation to fulfill all requirements for daily oral hygienic care.

  4. 2-D steering and propelling of acoustic bubble-powered microswimmers.

    PubMed

    Feng, Jian; Yuan, Junqi; Cho, Sung Kwon

    2016-06-21

    This paper describes bi-directional (linear and rotational) propelling and 2-D steering of acoustic bubble-powered microswimmers that are achieved in a centimeter-scale pool (beyond chip level scale). The core structure of a microswimmer is a microtube with one end open in which a gaseous bubble is trapped. The swimmer is propelled by microstreaming flows that are generated when the trapped bubble is oscillated by an external acoustic wave. The bubble oscillation and thus propelling force are highly dependent on the frequency of the acoustic wave and the bubble length. This dependence is experimentally studied by measuring the resonance behaviors of the testing pool and bubble using a laser Doppler vibrometer (LDV) and by evaluating the generated streaming flows. The key idea in the present 2-D steering is to utilize this dependence. Multiple bubbles with different lengths are mounted on a single microswimmer with a variety of arrangements. By controlling the frequency of the acoustic wave, only frequency-matched bubbles can strongly oscillate and generate strong propulsion. By arranging multiple bubbles of different lengths in parallel but with their openings opposite and switching the frequency of the acoustic wave, bi-directionally linear propelling motions are successfully achieved. The propelling forces are calculated by a CFD analysis using the Ansys Fluent® package. For bi-directional rotations, a similar method but with diagonal arrangement of bubbles on a rectangular swimmer is also applied. The rotation can be easily reversed when the frequency of the acoustic wave is switched. For 2-D steering, short bubbles are aligned perpendicular to long bubbles. It is successfully demonstrated that the microswimmer navigates through a T-junction channel under full control with and without carrying a payload. During the navigation, the frequency is the main control input to select and resonate targeted bubbles. All of these operations are achieved by a single

  5. 2-D steering and propelling of acoustic bubble-powered microswimmers.

    PubMed

    Feng, Jian; Yuan, Junqi; Cho, Sung Kwon

    2016-06-21

    This paper describes bi-directional (linear and rotational) propelling and 2-D steering of acoustic bubble-powered microswimmers that are achieved in a centimeter-scale pool (beyond chip level scale). The core structure of a microswimmer is a microtube with one end open in which a gaseous bubble is trapped. The swimmer is propelled by microstreaming flows that are generated when the trapped bubble is oscillated by an external acoustic wave. The bubble oscillation and thus propelling force are highly dependent on the frequency of the acoustic wave and the bubble length. This dependence is experimentally studied by measuring the resonance behaviors of the testing pool and bubble using a laser Doppler vibrometer (LDV) and by evaluating the generated streaming flows. The key idea in the present 2-D steering is to utilize this dependence. Multiple bubbles with different lengths are mounted on a single microswimmer with a variety of arrangements. By controlling the frequency of the acoustic wave, only frequency-matched bubbles can strongly oscillate and generate strong propulsion. By arranging multiple bubbles of different lengths in parallel but with their openings opposite and switching the frequency of the acoustic wave, bi-directionally linear propelling motions are successfully achieved. The propelling forces are calculated by a CFD analysis using the Ansys Fluent® package. For bi-directional rotations, a similar method but with diagonal arrangement of bubbles on a rectangular swimmer is also applied. The rotation can be easily reversed when the frequency of the acoustic wave is switched. For 2-D steering, short bubbles are aligned perpendicular to long bubbles. It is successfully demonstrated that the microswimmer navigates through a T-junction channel under full control with and without carrying a payload. During the navigation, the frequency is the main control input to select and resonate targeted bubbles. All of these operations are achieved by a single

  6. Single-frequency hybrid laser with an output power up to 3 W at a wavelength of 1064 nm

    SciTech Connect

    Trikshev, A I; Kurkov, Andrei S; Tsvetkov, V B

    2012-05-31

    A high-power single-frequency laser with an output power of 2.5 W in the cw regime at a wavelength of 1064 nm has been developed using a hybrid scheme based on a master singlefrequency semiconductor laser (wavelength 1064 nm, lasing linewidth less than 3 MHz) and a two-cascade fibre amplifier pumped by high-power laser diodes. At pump powers of 4.8 W in the first cascade and 6.8 W in the second cascade the total gain is about 100.

  7. Power Outputs and Volumetric Eruption Rates for Ionian Volcanoes from Galileo-NIMS Data

    NASA Technical Reports Server (NTRS)

    Davies, A. G.

    2001-01-01

    Volumetric eruption rates for a number of Io volcanoes are calculated as a function of volcanic thermal output. Thermal output is determined using 2-temperature fits to NIMS data. Typical eruption rates are larger than terrestrial eruptions of similar style. Additional information is contained in the original extended abstract.

  8. Predictors of maximal short-term power outputs in basketball players 14-16 years.

    PubMed

    Carvalho, Humberto M; Coelho E Silva, Manuel J; Figueiredo, António J; Gonçalves, Carlos E; Philippaerts, Renaat M; Castagna, Carlo; Malina, Robert M

    2011-05-01

    Relationships between growth, maturation and maximal short-term power outputs were investigated in 94 youth basketball players aged 14-16 years. Data included chronological age (CA), skeletal age (SA), years of training; body dimensions, estimated thigh volume, a running based short-term exercise assessed by the line drill test (LDT), the Bangsbo sprint test (BST) and short-term muscle power outputs with the Wingate anaerobic test (WAnT). Multiple linear regression analyses were used to estimate the effects of CA, skeletal maturity (SA/CA), years of training experience, body size and lower-limb volume on short-term performance in the LDT, BST and WAnT, respectively. Explained variances differed between cycle-ergometry outputs (52-54%) and running test performances (23-46%). The independent effects of predictors were small in the fatigue scores of the WAnT (4%) and the BST (11%). Skeletal maturity, body mass and leg length were primary predictors for all maximal short-term power output measures. Leg length was more relevant as a predictor than stature in the WAnT outputs, while stature and body mass appeared in the model with the running tests as dependent variable. Maximal short-term running abilities were also sensitive to years of training. In summary, skeletal maturation, body size and thigh muscle mass explained moderate to large proportions of the variance on maximal short-term performances of adolescent basketball players. The results highlight the importance of considering maturity status in evaluating the maximal short-term power outputs of adolescent athletes.

  9. Correlation of combustor acoustic power levels inferred from internal fluctuating pressure measurements

    NASA Technical Reports Server (NTRS)

    Vonglahn, U. H.

    1978-01-01

    Combustion chamber acoustic power levels inferred from internal fluctuating pressure measurements are correlated with operating conditions and chamber geometries over a wide range. The variables include considerations of chamber design (can, annular, and reverse-flow annular) and size, number of fuel nozzles, burner staging and fuel split, airflow and heat release rates, and chamber inlet pressure and temperature levels. The correlated data include those obtained with combustion component development rigs as well as engines.

  10. Thermometric- and Acoustic-Based Beam Power Monitor for Ultra-Bright X-Rays

    SciTech Connect

    Bentsen, Gregory; /Rochester U. /SLAC

    2010-08-25

    A design for an average beam power monitor for ultra-bright X-ray sources is proposed that makes simultaneous use of calorimetry and radiation acoustics. Radiation incident on a solid target will induce heating and ultrasonic vibrations, both of which may be measured to give a fairly precise value of the beam power. The monitor is intended for measuring ultra-bright Free-Electron Laser (FEL) X-ray beams, for which traditional monitoring technologies such as photo-diodes or scintillators are unsuitable. The monitor consists of a Boron Carbide (B{sub 4}C) target designed to absorb most of the incident beam's energy. Resistance temperature detectors (RTD) and piezoelectric actuators are mounted on the outward faces of the target to measure the temperature changes and ultrasonic vibrations induced by the incident beam. The design was tested using an optical pulsed beam (780 nm, 120 and 360 Hz) from a Ti:sapphire oscillator at several energies between 0.8 and 2.6 mJ. The RTDs measured an increase in temperature of about 10 K over a period of several minutes. The piezoelectric sensors recorded ringing acoustic oscillations at 580 {+-} 40 kHz. Most importantly, the amplitude of the acoustic signals was observed to scale linearly with beam power up to 2 mJ of pulse energy. Above this pulse energy, the vibrational signals became nonlinear. Several causes for this nonlinearity are discussed, including amplifier saturation and piezoelectric saturation. Despite this nonlinearity, these measurements demonstrate the feasibility of such a beam power measurement device. The advantage of two distinct measurements (acoustic and thermometric) provides a useful method of calibration that is unavailable to current LCLS diagnostics tools.

  11. Single-transverse-mode near-IR superluminescent diodes with cw output power up to 100 mW

    SciTech Connect

    Andreeva, E V; Il'chenko, S N; Kostin, Yu O; Yakubovich, S D

    2014-10-29

    A series of light-emitting modules based on single-mode quantum-well superluminescent diodes with centre emission wavelengths of about 790, 840, 960 and 1060 nm and a cw output power up to 100 mW in free space is developed. A sufficiently long service life of these devices is demonstrated. (lasers)

  12. Development and evaluation of a new bicycle instrument for measurements of pedal forces and power output in cycling.

    PubMed

    Stapelfeldt, B; Mornieux, G; Oberheim, R; Belli, A; Gollhofer, A

    2007-04-01

    Determination of pedal forces is a prerequisite to analyse cycling performance capability from a biomechanical point of view. Comparing existing pedal force measurement systems, there are methodological or practical limitations regarding the requirements of scientific sports performance research and enhancement. Therefore, the aim of this study was to develop and to validate a new bicycle instrument that enables pedal forces as well as power output measurements with a free choice of pedal system. The instrument (Powertec-System) is based on force transducer devices, using the Hall-Effect and being mounted between the crank and the pedal. Validation of the method was evaluated by determining the accuracy, the cross talk effect, the influence of lateral forces, the reproducibility and, finally, a possible drift under static conditions. Dynamic tests were conducted to validate the power output measurement in reference to the SRM-System. The mean error of the present system was -0.87 +/- 4.09 % and -1.86 +/- 6.61 % for, respectively, the tangential and radial direction. Cross talk, lateral force influence, reproducibility and drift mean values were < +/- 7 %, < or = 2.4 %, < 0.8 % and 0.02 N x min (-1), respectively. In dynamic conditions, the power output measurement error could be kept below 2.35 %. In conclusion, this method offers the possibility for both valid pedal forces and power output measurements. Moreover, the instrument allows measurements with every pedal system. This method has an interesting potential for biomechanical analyses in cycling research and performance enhancement.

  13. Diaphragm efficiency estimated as power output relative to activation in chronic obstructive pulmonary disease.

    PubMed

    Finucane, Kevin E; Singh, Bhajan

    2012-11-01

    Muscle efficiency increases with fiber length and decreases with load. Diaphragm efficiency (Eff(di)) in healthy humans, measured as power output (Wdi) relative to the root mean square of diaphragm electromyogram (RMS(di)), increases with hyperpnea due to phasic activity of abdominal muscles acting to increase diaphragm length at end expiration (L(di ee)) and decrease inspiratory load. In chronic obstructive pulmonary disease (COPD), hyperpnea may decrease Eff(di) if L(di ee) decreases and load increases due to airflow obstruction and dynamic hyperinflation. To examine this hypothesis, we measured Eff(di) in six COPD subjects (mean forced expiratory volume in 1 s: 54% predicted) when breathing air and at intervals during progressive hypercapnic hyperpnea. Wdi was measured as the product of mean inspiratory transdiaphragmatic pressure (ΔPdi(mean)), diaphragm tidal volume measured fluoroscopically, and 1/inspiratory duration. Results were compared with those of six healthy subjects reported previously. In COPD, L(di ee) was normal when breathing air. ΔPdi(mean) and Wdi increased normally, and RMS(di) increased disproportionately (P = 0.01) with hyperpnea, and, unlike health, inspiratory capacity (IC), L(di ee), and Eff(di) did not increase. IC and L(di ee) were constant with hyperpnea because mean expiratory flow increased as expiratory duration decreased (r(2) = 0.65), and because expiratory flow was terminated actively by the balance between expiratory and inspiratory muscle forces near end expiration, and these forces increased proportionately with hyperpnea (r(2) = 0.49). At maximum ventilation, diaphragm radius of curvature at end inspiration increased in COPD (P = 0.04) but not controls; diaphragm radius of curvature at end inspiration and ln(Eff(di)) were negatively correlated (P = 0.01). Thus in COPD with modest airflow obstruction, Eff(di) did not increase normally with hyperpnea due to a constant L(di ee) and inspiratory flattening of the diaphragm.

  14. Thermal Considerations of Space Solar Power Concepts with 3.5 GW RF Output

    NASA Technical Reports Server (NTRS)

    Choi, Michael K.

    2000-01-01

    This paper presents the thermal challenge of the Space Solar Power (SSP) design concepts with a 3.5 GW radio-frequency (RF) output. High efficiency klystrons are thermally more favored than solid state (butterstick) to convert direct current (DC) electricity to radio-frequency (RF) energy at the transmitters in these concepts. Using klystrons, the heat dissipation is 0.72 GW. Using solid state, the heat dissipation is 2.33 GW. The heat dissipation of the klystrons is 85% at 500C, 10% at 300C, and 5% at 125C. All the heat dissipation of the solid state is at 100C. Using klystrons, the radiator area is 74,500 square m Using solid state, the radiator area is 2,362,200 square m Space constructable heat pipe radiators are assumed in the thermal analysis. Also, to make the SSP concepts feasible, the mass of the heat transport system must be minimized. The heat transport distance from the transmitters to the radiators must be minimized. It can be accomplished by dividing the radiator into a cluster of small radiators, so that the heat transport distances between the klystrons and radiators can be minimized. The area of each small radiator is on the order of 1 square m. Two concepts for accommodating a cluster of small radiators are presented. If the distance between the transmitters and radiators is 1.5 m or less, constant conductance heat pipes (CCHPs) are acceptable for heat transport. If the distance exceeds 1.5 m, loop heat pipes (LHPs) are needed.

  15. Influence of different output powers on the efficacy of photodynamic therapy with 809-nm diode laser and indocyanine green

    NASA Astrophysics Data System (ADS)

    Topaloglu, Nermin; Yuksel, Sahru; Gulsoy, Murat

    2013-02-01

    Photodynamic therapy (PDT) is an alternative antimicrobial treatment method. Different wavelengths of light sources mostly in the visible spectrum have been investigated for antimicrobial Photodynamic Therapy. Even though the wavelengths in near infrared spectrum have the advantage of higher penetration capability in biological tissue, they have not been preferred for PDT because of their possible photothermal effect in biological tissues. In our previous studies, the desired PDT effect was achieved with 809-nm diode laser and indocyanine green (ICG) on drug resistant pathogens. In this study, it was aimed to investigate the influence of different output powers during PDT applications with 809-nm diode laser to clarify whether there is a photothermal effect to kill the pathogens or only the photochemical effect of photodynamic therapy. 4 different output powers (500 mW, 745 mW, 1000 mW, 1500 mW) were examined in Laseronly and PDT groups of P. aeruginosa ATCC 27853 in vitro. In the PDT groups, a non-phototoxic ICG concentration (50 μl/ml) has been chosen to eliminate the toxic effect of ICG and evaluate only the thermal effect of laser. Applied energy dose (252 J/cm2) was kept constant by increasing the exposure duration (300, 240, 180 and 120 seconds respectively). These output powers in Laser-only or PDT groups did not seem to cause photothermal effect. There was not any significant decrease or increase on bacterial load after the applications with different output powers. Higher output powers in PDT groups with the same ICG concentration did not cause any higher killing effect.

  16. Acoustic energy transmission in cast iron pipelines

    NASA Astrophysics Data System (ADS)

    Kiziroglou, Michail E.; Boyle, David E.; Wright, Steven W.; Yeatman, Eric M.

    2015-12-01

    In this paper we propose acoustic power transfer as a method for the remote powering of pipeline sensor nodes. A theoretical framework of acoustic power propagation in the ceramic transducers and the metal structures is drawn, based on the Mason equivalent circuit. The effect of mounting on the electrical response of piezoelectric transducers is studied experimentally. Using two identical transducer structures, power transmission of 0.33 mW through a 1 m long, 118 mm diameter cast iron pipe, with 8 mm wall thickness is demonstrated, at 1 V received voltage amplitude. A near-linear relationship between input and output voltage is observed. These results show that it is possible to deliver significant power to sensor nodes through acoustic waves in solid structures. The proposed method may enable the implementation of acoustic - powered wireless sensor nodes for structural and operation monitoring of pipeline infrastructure.

  17. Leg joint power output during progressive resistance FES-LCE cycling in SCI subjects: developing an index of fatigue

    PubMed Central

    Haapala, Stephenie A; Faghri, Pouran D; Adams, Douglas J

    2008-01-01

    Background The purpose of this study was to investigate the biomechanics of the hip, knee and ankle during a progressive resistance cycling protocol in an effort to detect and measure the presence of muscle fatigue. It was hypothesized that knee power output can be used as an indicator of fatigue in order to assess the cycling performance of SCI subjects. Methods Six spinal cord injured subjects (2 incomplete, 4 complete) between the ages of twenty and fifty years old and possessing either a complete or incomplete spinal cord injury at or below the fourth cervical vertebra participated in this study. Kinematic data and pedal forces were recorded during cycling at increasing levels of resistance. Ankle, knee and hip power outputs and resultant pedal force were calculated. Ergometer cadence and muscle stimulation intensity were also recorded. Results The main findings of this study were: (a) ankle and knee power outputs decreased, whereas hip power output increased with increasing resistance, (b) cadence, stimulation intensity and resultant pedal force in that combined order were significant predictors of knee power output and (c) knowing the value of these combined predictors at 10 rpm, an index of fatigue can be developed, quantitatively expressing the power capacity of the knee joint with respect to a baseline power level defined as fatigue. Conclusion An index of fatigue was successfully developed, proportionalizing knee power capacity during cycling to a predetermined value of fatigue. The fatigue index value at 0/8th kp, measured 90 seconds into active, unassisted pedaling was 1.6. This indicates initial power capacity at the knee to be 1.6 times greater than fatigue. The fatigue index decreased to 1.1 at 2/8th kp, representing approximately a 30% decrease in the knee's power capacity within a 4 minute timespan. These findings suggest that the present cycling protocol is not sufficient for a rider to gain the benefits of FES and thus raises speculation as to

  18. Output Power Limitations and Improvements in Passively Mode Locked GaAs/AlGaAs Quantum Well Lasers

    PubMed Central

    Tandoi, Giuseppe; Ironside, Charles N.; Marsh, John H.; Bryce, A. Catrina

    2013-01-01

    We report a novel approach for increasing the output power in passively mode locked semiconductor lasers. Our approach uses epitaxial structures with an optical trap in the bottom cladding that enlarges the vertical mode size to scale the pulse saturation energy. With this approach we demonstrate a very high peak power of 9.8 W per facet, at a repetition rate of 6.8 GHz and with pulse duration of 0.71 ps. In particular, we compare two GaAs/AlGaAs epilayer designs, a double quantum well design operating at 830 nm and a single quantum well design operating at 795 nm, with vertical mode sizes of 0.5 and 0.75 μm, respectively. We show that a larger mode size not only shifts the mode locking regime of operation towards higher powers, but also produces other improvements in respect of two main failure mechanisms that limit the output power: the catastrophic optical mirror damage and the catastrophic optical saturable absorber damage. For the 830 nm material structure, we also investigate the effect of non-absorbing mirrors on output power and mode locked operation of colliding pulse mode locked lasers. PMID:23843678

  19. A low-cost biofuel cell with pH-dependent power output based on porous carbon as matrix.

    PubMed

    Liu, Ying; Wang, Mingkui; Zhao, Feng; Liu, Baifeng; Dong, Shaojun

    2005-08-19

    A glucose/O2 biofuel cell (BFC) possessing a pH-dependent power output was fabricated by taking porous carbon (PC) as the matrix to load glucose oxidase or fungi laccase as the catalysts. The electrolytes in the anode and cathode compartments contain ferrocene monocarboxylic acid and 2,2'-azino-bis-(3-ethylbenzthiazoline-6-sulfonic acid) diammonium salt as the mediators, respectively. The power of the BFC was enhanced significantly by using PC as the matrix, rather than glassy carbon electrode. Additionally, the power output of the BFC decreases as the pH of the solution increases from 4.0 to 7.0, which provides a simple and efficient method to achieve the required power output. More importantly, the BFC can operate at pH 6.0, and even at pH 7.0, which overcomes the requirement for cathode solutions of pH<5.0 when using fungi laccase as a catalyst. Operation of the BFC at neutral pH may provide a means to power medical devices implanted in physiological systems. The facile and low-cost fabrication of this BFC may enable its development for other applications.

  20. Output Power Limitations and Improvements in Passively Mode Locked GaAs/AlGaAs Quantum Well Lasers.

    PubMed

    Tandoi, Giuseppe; Ironside, Charles N; Marsh, John H; Bryce, A Catrina

    2012-03-01

    We report a novel approach for increasing the output power in passively mode locked semiconductor lasers. Our approach uses epitaxial structures with an optical trap in the bottom cladding that enlarges the vertical mode size to scale the pulse saturation energy. With this approach we demonstrate a very high peak power of 9.8 W per facet, at a repetition rate of 6.8 GHz and with pulse duration of 0.71 ps. In particular, we compare two GaAs/AlGaAs epilayer designs, a double quantum well design operating at 830 nm and a single quantum well design operating at 795 nm, with vertical mode sizes of 0.5 and 0.75 μm, respectively. We show that a larger mode size not only shifts the mode locking regime of operation towards higher powers, but also produces other improvements in respect of two main failure mechanisms that limit the output power: the catastrophic optical mirror damage and the catastrophic optical saturable absorber damage. For the 830 nm material structure, we also investigate the effect of non-absorbing mirrors on output power and mode locked operation of colliding pulse mode locked lasers.

  1. Final report on testing of TOPAZ II unit Ya-21u: Output power characteristics and system capabilities

    SciTech Connect

    Luchau, D.W.; Sinkevich, V.G.; Wernsman, B.; Mulder, D.M.

    1996-03-01

    A final report on the output power characteristics and capabilities of the TOPAZ II Space Nuclear Power Unit Ya-21u is presented. Results showed that after a total of almost 8,000 hours of system testing in the U.S. and Russia, several emergency cooldowns, and three inadvertent air introductions to the interelectrode gap (IEG) that the TOPAZ II demonstrates the potential for providing reliable power in a space environment. Output power optimizations and system characteristics following a shock and vibration test are shown. These tests were performed using electrical heaters that simulate nuclear fuel heating. This paper will focus primarily on the changes in output power characteristics over the lifetime of Ya-21u. All U.S. testing was conducted at the Thermionic System Evaluation Test (TSET) Facility of the New Mexico Engineering Research Institute (NMERI) as a part of the TOPAZ International Program (TIP). TIP is managed by the Air Force Phillips Laboratory (PL) for the Ballistic Missile Defense Organization (BMDO). {copyright} {ital 1996 American Institute of Physics.}

  2. Holmium-doped 2.1 μm waveguide chip laser with an output power > 1 W.

    PubMed

    Lancaster, D G; Stevens, V J; Michaud-Belleau, V; Gross, S; Fuerbach, A; Monro, T M

    2015-12-14

    We demonstrate the increasing applicability of compact ultra-fast laser inscribed glass guided-wave lasers and report the highest-power glass waveguide laser with over 1.1 W of output power in monolithic operation in the short-infrared near 2070 nm achieved (51% incident slope efficiency). The holmium doped ZBLAN chip laser is in-band pumped by a 1945 nm thulium fiber laser. When operated in an extended-cavity configuration, over 1 W of output power is realized in a linearly polarized beam. Broad and continuous tunability of the extended-cavity laser is demonstrated from 2004 nm to 2099 nm. Considering its excellent beam quality of M² = 1.08, this laser shows potential as a flexible master oscillator for single frequency and mode-locking applications. PMID:26699055

  3. Work output and efficiency at maximum power of linear irreversible heat engines operating with a finite-sized heat source.

    PubMed

    Izumida, Yuki; Okuda, Koji

    2014-05-01

    We formulate the work output and efficiency for linear irreversible heat engines working between a finite-sized hot heat source and an infinite-sized cold heat reservoir until the total system reaches the final thermal equilibrium state with a uniform temperature. We prove that when the heat engines operate at the maximum power under the tight-coupling condition without heat leakage the work output is just half of the exergy, which is known as the maximum available work extracted from a heat source. As a consequence, the corresponding efficiency is also half of its quasistatic counterpart.

  4. Work output and efficiency at maximum power of linear irreversible heat engines operating with a finite-sized heat source.

    PubMed

    Izumida, Yuki; Okuda, Koji

    2014-05-01

    We formulate the work output and efficiency for linear irreversible heat engines working between a finite-sized hot heat source and an infinite-sized cold heat reservoir until the total system reaches the final thermal equilibrium state with a uniform temperature. We prove that when the heat engines operate at the maximum power under the tight-coupling condition without heat leakage the work output is just half of the exergy, which is known as the maximum available work extracted from a heat source. As a consequence, the corresponding efficiency is also half of its quasistatic counterpart. PMID:24856684

  5. Work Output and Efficiency at Maximum Power of Linear Irreversible Heat Engines Operating with a Finite-Sized Heat Source

    NASA Astrophysics Data System (ADS)

    Izumida, Yuki; Okuda, Koji

    2014-05-01

    We formulate the work output and efficiency for linear irreversible heat engines working between a finite-sized hot heat source and an infinite-sized cold heat reservoir until the total system reaches the final thermal equilibrium state with a uniform temperature. We prove that when the heat engines operate at the maximum power under the tight-coupling condition without heat leakage the work output is just half of the exergy, which is known as the maximum available work extracted from a heat source. As a consequence, the corresponding efficiency is also half of its quasistatic counterpart.

  6. W5″ Test: A simple method for measuring mean power output in the bench press exercise.

    PubMed

    Tous-Fajardo, Julio; Moras, Gerard; Rodríguez-Jiménez, Sergio; Gonzalo-Skok, Oliver; Busquets, Albert; Mujika, Iñigo

    2016-11-01

    The aims of the present study were to assess the validity and reliability of a novel simple test [Five Seconds Power Test (W5″ Test)] for estimating the mean power output during the bench press exercise at different loads, and its sensitivity to detect training-induced changes. Thirty trained young men completed as many repetitions as possible in a time of ≈5 s at 25%, 45%, 65% and 85% of one-repetition maximum (1RM) in two test sessions separated by four days. The number of repetitions, linear displacement of the bar and time needed to complete the test were recorded by two independent testers, and a linear encoder was used as the criterion measure. For each load, the mean power output was calculated in the W5″ Test as mechanical work per time unit and compared with that obtained from the linear encoder. Subsequently, 20 additional subjects (10 training group vs. 10 control group) were assessed before and after completing a seven-week training programme designed to improve maximal power. Results showed that both assessment methods correlated highly in estimating mean power output at different loads (r range: 0.86-0.94; p < .01) and detecting training-induced changes (R(2): 0.78). Good to excellent intra-tester (intraclass correlation coefficient (ICC) range: 0.81-0.97) and excellent inter-tester (ICC range: 0.96-0.99; coefficient of variation range: 2.4-4.1%) reliability was found for all loads. The W5″ Test was shown to be a valid, reliable and sensitive method for measuring mean power output during the bench press exercise in subjects who have previous resistance training experience.

  7. Moisture estimation in power transformer oil using acoustic signals and spectral kurtosis

    NASA Astrophysics Data System (ADS)

    Leite, Valéria C. M. N.; Veloso, Giscard F. C.; Borges da Silva, Luiz Eduardo; Lambert-Torres, Germano; Borges da Silva, Jonas G.; Onofre Pereira Pinto, João

    2016-03-01

    The aim of this paper is to present a new technique for estimating the contamination by moisture in power transformer insulating oil based on the spectral kurtosis analysis of the acoustic signals of partial discharges (PDs). Basically, in this approach, the spectral kurtosis of the PD acoustic signal is calculated and the correlation between its maximum value and the moisture percentage is explored to find a function that calculates the moisture percentage. The function can be easily implemented in DSP, FPGA, or any other type of embedded system for online moisture monitoring. To evaluate the proposed approach, an experiment is assembled with a piezoelectric sensor attached to a tank, which is filled with insulating oil samples contaminated by different levels of moisture. A device generating electrical discharges is submerged into the oil to simulate the occurrence of PDs. Detected acoustic signals are processed using fast kurtogram algorithm to extract spectral kurtosis values. The obtained data are used to find the fitting function that relates the water contamination to the maximum value of the spectral kurtosis. Experimental results show that the proposed method is suitable for online monitoring system of power transformers.

  8. Incident signal power comparison for localization of concurrent multiple acoustic sources.

    PubMed

    Salvati, Daniele; Canazza, Sergio

    2014-01-01

    In this paper, a method to solve the localization of concurrent multiple acoustic sources in large open spaces is presented. The problem of the multisource localization in far-field conditions is to correctly associate the direction of arrival (DOA) estimated by a network array system to the same source. The use of systems implementing a Bayesian filter is a traditional approach to address the problem of localization in multisource acoustic scenario. However, in a real noisy open space the acoustic sources are often discontinuous with numerous short-duration events and thus the filtering methods may have difficulty to track the multiple sources. Incident signal power comparison (ISPC) is proposed to compute DOAs association. ISPC is based on identifying the incident signal power (ISP) of the sources on a microphone array using beamforming methods and comparing the ISP between different arrays using spectral distance (SD) measurement techniques. This method solves the ambiguities, due to the presence of simultaneous sources, by identifying sounds through a minimization of an error criterion on SD measures of DOA combinations. The experimental results were conducted in an outdoor real noisy environment and the ISPC performance is reported using different beamforming techniques and SD functions. PMID:24701179

  9. Incident Signal Power Comparison for Localization of Concurrent Multiple Acoustic Sources

    PubMed Central

    2014-01-01

    In this paper, a method to solve the localization of concurrent multiple acoustic sources in large open spaces is presented. The problem of the multisource localization in far-field conditions is to correctly associate the direction of arrival (DOA) estimated by a network array system to the same source. The use of systems implementing a Bayesian filter is a traditional approach to address the problem of localization in multisource acoustic scenario. However, in a real noisy open space the acoustic sources are often discontinuous with numerous short-duration events and thus the filtering methods may have difficulty to track the multiple sources. Incident signal power comparison (ISPC) is proposed to compute DOAs association. ISPC is based on identifying the incident signal power (ISP) of the sources on a microphone array using beamforming methods and comparing the ISP between different arrays using spectral distance (SD) measurement techniques. This method solves the ambiguities, due to the presence of simultaneous sources, by identifying sounds through a minimization of an error criterion on SD measures of DOA combinations. The experimental results were conducted in an outdoor real noisy environment and the ISPC performance is reported using different beamforming techniques and SD functions. PMID:24701179

  10. 1KW Power Transmission Using Wireless Acoustic-Electric Feed-Through (WAEF)

    NASA Technical Reports Server (NTRS)

    Sherrit, S.; Bao, X.; Badescu, M.; Aldrich, J.; Bar-Cohen, Y.; Biederman, W.

    2008-01-01

    A variety of space applications require the delivery of power into sealed structures. Since the structural integrity can be degraded by holes for cabling we present an alternative method of delivering power and information using stress waves to the internal space of a sealed structure. One particular application of this technology is in sample return missions where it is critical to preserve the sample integrity and to prevent earth contamination. Therefore, the container has to be hermetically sealed and the integrity of the seal must be monitored in order to insure to a high degree of reliability the integrity of the sample return vessel. In this study we investigated the use of piezoelectric acoustic-electric power feed-through devices to transfer electric power wirelessly through a solid wall by using elastic or acoustic waves. The technology is applicable to a range of space and terrestrial applications where power is required by electronic equipment inside sealed containers, vacuum or pressure vessels, etc., where holes in the wall are prohibitive or may result in significant structural performance degradation or unnecessarily complex designs. To meet requirements of higher power applications, the feasibility to transfer kilowatts level power was investigated. Pre-stressed longitudinal piezoelectric feed-through devices were analyzed by finite element models and an equivalent circuit model was developed to predict the power transfer characteristics to different electric loads. Based on the results of the analysis a prototype device was designed, fabricated and a demonstration of the transmission of electric power up to 1.068-kW was successfully conducted. Efficiencies in the 80-90% range were also demonstrated and methods to increase the efficiency further are currently being considered.

  11. Genetic Variability of Flight Metabolism in DROSOPHILA MELANOGASTER . III. Effects of Gpdh Allozymes and Environmental Temperature on Power Output

    PubMed Central

    Barnes, Phillip T.; Laurie-Ahlberg, Cathy C.

    1986-01-01

    The effect of allozyme variation at the sn-glycerol-3-phosphate dehydrogenase (Gpdh) locus on variation in the mechanical power output of the flight muscles of Drosophila melanogaster was investigated. The influence of different rearing and flight temperatures and of their interactions with the Gpdh allozymic genotypes (allotypes) on flight ability also were analyzed. Populations from three continents were used, and Gpdh allotypes were generated from crosses between randomly paired isofemale lines made autozygous for each of the two alleles by inbreeding. Measurements made during tethered flight, together with wing morphology, were used to estimate power output using both Weis-Fogh's and Ellington's formulas.—Analyses of variance (ANOVA) indicated significant main effects for both environmental components (rearing and flight temperatures) but for only one of the three genetic components (genetic backgrounds within continent); Gpdh allotypes and populations (continent of origin) were not significant. The interaction between rearing and flight temperature was highly significant, indicating some physiological adaptation. The effect of Gpdh allozymes depended on both rearing and flight temperature and was either significant or marginally so, depending on which set of formulas was used. In either case, the S/S allotype showed a 2–4% greater power output than the F/F allotype at low temperature for both interactions. In addition, the S/S allotype showed significantly greater power output than the F/F allotype among flies raised at 15° and flown at 15°, whereas the reverse was true for flies raised at 30° and flown at 30°. Significant differences among the three allotypes for GPDH activity level were found in general, with S/S having the highest, F/S intermediate and F/F the lowest activity, and an inverse relationship existed between rearing temperature and activity.—The temperature effects on power output are consistent with the geographical and seasonal

  12. A Comparative in Vitro Study of Power Output Deterioration over Time Between Ho:YAG Laser Fibers from Different Manufacturers as a Function of Deflection and Power Input

    PubMed Central

    Bourdoumis, Andreas; Christopoulos, Panagiotis; Raj, Nirmal; Fedder, Artemis; Buchholz, Noor

    2016-01-01

    Objectives To investigate the performance of laser fibers from 6 major manufacturers in vitro and to identify the effect of time and angulations (180° and 0°) on fiber power output. Materials and Methods Overall, 36 single-use fibers were used. Each was tested with an energy input of 0.8, 1.4 and 2.0 Joules. A power detector measured power output after 1, 5, 10 and 15 minutes for three 15-minute cycles of continuous use. For the first 2 cycles, the fiber was bent to 180° with the use of a pre fabricated mould. Analysis of the data was performed by ANOVA and Tukey's test when the results were significant amongst groups. Statistical significance was deemed p < 0.05. Results No fiber fracture occurred. There was no significant difference in output at 15 minutes of continuous use at 0° and 180°. The reduction in energy output at the 15th minute of continuous use at 180° was not significant for any fiber type or initial input. Only output differences between the fibers proved to be significant (p = 0.001). Conclusion Fiber fracture and decline in performance is not due to deflection and continuous use. Frictional forces that occur between the fiber tip and the stone fragments may be responsible. PMID:26989365

  13. Effect of a novel pedal design on maximal power output and mechanical efficiency in well-trained cyclists.

    PubMed

    Koninckx, Erwin; van Leemputte, Marc; Hespel, Peter

    2008-08-01

    In this study, we evaluated the effects of a novel pedal design, characterized by a downward and forward shift of the cleat fixing platform relative to the pedal axle, on maximal power output and mechanical efficiency in 22 well-trained cyclists. Maximal power output was measured during a series of short (5-s) intermittent sprints on an isokinetic cycle ergometer at cadences from 40 to 120 rev min(-1). Mechanical efficiency was evaluated during a submaximal incremental exercise test on a bicycle ergometer using continuous VO(2) and VCO(2) measurement. Similar tests with conventional pedals and the novel pedals, which were mounted on the individual racing bike of the participant, were randomized. Maximal power was greater with novel pedals than with conventional pedals (between 6.0%, s(x) = 1.5 at 40 rev min(-1) and 1.8%, s(x) = 0.7 at 120 rev min(-1); P = 0.01). Torque production between crank angles of 60 degrees and 150 degrees was higher with novel pedals than with conventional pedals (P = 0.004). The novel pedal design did not affect whole-body VO(2) or VCO(2). Mechanical efficiency was greater with novel pedals than with conventional pedals (27.2%, s(x) = 0.9 and 25.1%, s(x) = 0.9% respectively; P = 0.047; effect size = 0.9). In conclusion, the novel pedals can increase maximal power output and mechanical efficiency in well-trained cyclists.

  14. Enhancing photovoltaic output power by 3-band spectrum-splitting and concentration using a diffractive micro-optic.

    PubMed

    Mohammad, Nabil; Wang, Peng; Friedman, Daniel J; Menon, Rajesh

    2014-10-20

    We report the enhancement of photovoltaic output power by separating the incident spectrum into 3 bands, and concentrating these bands onto 3 different photovoltaic cells. The spectrum-splitting and concentration is achieved via a thin, planar micro-optical element that demonstrates high optical efficiency over the entire spectrum of interest. The optic (which we call a polychromat) was designed using a modified version of the direct-binary-search algorithm. The polychromat was fabricated using grayscale lithography. Rigorous optical characterization demonstrates excellent agreement with simulation results. Electrical characterization of the solar cells made from GaInP, GaAs and Si indicate increase in the peak output power density of 43.63%, 30.84% and 30.86%, respectively when compared to normal operation without the polychromat. This represents an overall increase of 35.52% in output power density. The potential for cost-effective large-area manufacturing and for high system efficiencies makes our approach a strong candidate for low cost solar power.

  15. Enhancing photovoltaic output power by 3-band spectrum-splitting and concentration using a diffractive micro-optic

    SciTech Connect

    Mohammad, Nabil; Wang, Peng; Friedman, Daniel J.; Menon, Rajesh

    2014-09-17

    We report the enhancement of photovoltaic output power by separating the incident spectrum into 3 bands, and concentrating these bands onto 3 different photovoltaic cells. The spectrum-splitting and concentration is achieved via a thin, planar micro-optical element that demonstrates high optical efficiency over the entire spectrum of interest. The optic (which we call a polychromat) was designed using a modified version of the direct-binary-search algorithm. The polychromat was fabricated using grayscale lithography. Rigorous optical characterization demonstrates excellent agreement with simulation results. Electrical characterization of the solar cells made from GaInP, GaAs and Si indicate increase in the peak output power density of 43.63%, 30.84% and 30.86%, respectively when compared to normal operation without the polychromat. This represents an overall increase of 35.52% in output power density. As a result, the potential for cost-effective large-area manufacturing and for high system efficiencies makes our approach a strong candidate for low cost solar power.

  16. Aircraft IR/acoustic detection evaluation. Volume 2: Development of a ground-based acoustic sensor system for the detection of subsonic jet-powered aircraft

    NASA Technical Reports Server (NTRS)

    Kraft, Robert E.

    1992-01-01

    The design and performance of a ground-based acoustic sensor system for the detection of subsonic jet-powered aircraft is described and specified. The acoustic detection system performance criteria will subsequently be used to determine target detection ranges for the subject contract. Although the defined system has never been built and demonstrated in the field, the design parameters were chosen on the basis of achievable technology and overall system practicality. Areas where additional information is needed to substantiate the design are identified.

  17. Biosonar resolving power: echo-acoustic perception of surface structures in the submillimeter range.

    PubMed

    Simon, Ralph; Knörnschild, Mirjam; Tschapka, Marco; Schneider, Annkathrin; Passauer, Nadine; Kalko, Elisabeth K V; von Helversen, Otto

    2014-01-01

    The minimum distance for which two points still can be separated from each other defines the resolving power of a visual system. In an echo-acoustic context, the resolving power is usually measured as the smallest perceivable distance of two reflecting surfaces on the range axis and is found to be around half a millimeter for bats employing frequency modulated (FM) echolocation calls. Only few studies measured such thresholds with physical objects, most often bats were trained on virtual echoes i.e., echoes generated and played back by a computer; moreover, bats were sitting while they received the stimuli. In these studies differences in structure depth between 200 and 340 μm were found. However, these low thresholds were never verified for free-flying bats and real physical objects. Here, we show behavioral evidence that the echo-acoustic resolving power for surface structures in fact can be as low as measured for computer generated echoes and even lower, sometimes below 100 μm. We found this exceptional fine discrimination ability only when one of the targets showed spectral interferences in the frequency range of the bats' echolocation call while the other target did not. This result indicates that surface structure is likely to be perceived as a spectral quality rather than being perceived strictly in the time domain. Further, it points out that sonar resolving power directly depends on the highest frequency/shortest wavelength of the signal employed.

  18. Acoustic Power Absorption and its Relation to Vector Magnetic Field of a Sunspot

    NASA Astrophysics Data System (ADS)

    Gosain, S.; Mathew, S. K.; Venkatakrishnan, P.

    2011-02-01

    The distribution of acoustic power over sunspots shows an enhanced absorption near the umbra - penumbra boundary. Previous studies revealed that the region of enhanced absorption coincides with the region of strongest transverse potential field. The aim of this paper is to i) utilize the high-resolution vector magnetograms derived using Hinode SOT/SP observations and study the relationship between the vector magnetic field and power absorption and ii) study the variation of power absorption in sunspot penumbrae due to the presence of spine-like radial structures. It is found that i) both potential and observed transverse fields peak at a similar radial distance from the center of the sunspot, and ii) the magnitude of the transverse field, derived from Hinode observations, is much larger than the potential transverse field derived from SOHO/MDI longitudinal-field observations. In the penumbra, the radial structures called spines (intra-spines) have stronger (weaker) field strength and are more vertical (horizontal). The absorption of acoustic power in the spine and intra-spine shows different behavior, with the absorption being larger in the spine as compared to the intra-spine.

  19. An optimized self-powered switching circuit for non-linear energy harvesting with low voltage output

    NASA Astrophysics Data System (ADS)

    Lallart, Mickaël; Guyomar, Daniel

    2008-06-01

    Harvesting energy from environmental sources has been of particular interest these last few years. Microgenerators that can power electronic systems are a solution for the conception of autonomous, wireless devices. They allow the removal of bulky and costly wiring, as well as complex maintenance and environmental issues for battery-powered systems. In particular, using piezoelectric generators for converting vibrational energy to electrical energy is an intensively investigated field. In this domain, it has been shown that the harvested energy can be greatly improved by the use of an original non-linear treatment of the piezoelectric voltage called SSHI (Synchronized Switch Harvesting on Inductor), which consists in intermittently switching the piezoelectric element on a resonant electrical network for a very short time. However, the integration of miniaturized microgenerators with low voltage output (e.g. MEMS microgenerators) has not been widely studied. In the case of low voltage output, the losses introduced by voltage gaps of discrete components such as diodes or transistors can no longer be neglected. Therefore the purpose of this paper is to propose a model that takes into account such losses as well as a new architecture for the SSHI energy harvesting circuit that limits such losses in the harvesting process. While most of the study uses an externally powered microcontroller for the non-linear treatment, this circuit is fully self-powered, thus providing an enhanced autonomous microgenerator. In particular this circuit aims at limiting the effect of non-linear components with a voltage gap such as diodes. It is shown both theoretically and experimentally that the harvested power can be significantly increased using such a circuit. In particular, experimental measurements performed on a cantilever beam show that the circuit allows a 160% increase of the harvested power compared to a standard energy harvesting circuit, while the classical implementation of

  20. Power outputs in the concentric phase of resistance exercises performed in the interval mode on stable and unstable surfaces.

    PubMed

    Zemková, Erika; Jeleň, Michal; Kováčiková, Zuzana; Ollé, Gábor; Vilman, Tomáš; Hamar, Dušan

    2012-12-01

    The study compares power outputs in the concentric phase of chest presses and squats performed in the interval mode on stable and unstable surface, respectively. A group of 16 physical education students performed randomly on different days 6 sets of 8 repetitions of (a) chest presses on the bench and Swiss ball, respectively, and (b) squats on stable support base and Bosu ball, respectively, with 2 minutes of rest period between sets. The exercises were performed with previously established 70% of 1 repetition maximum under stable conditions. A PC-based system FiTRO Dyne Premium was used to monitor force and velocity and to calculate power. The results showed significantly lower power outputs when resistance exercises were performed on an unstable than a stable support base. In the initial set, mean power in concentric phase of lifting decreased more profoundly under unstable than under stable conditions during both chest presses (13.2 and 7.7%, respectively) and squats (10.3 and 7.2%, respectively). In the final set, the reduction rates of mean power in the concentric phase of chest presses were significantly (p < 0.05) greater on the Swiss ball than on the bench (19.9 and 11.8%, respectively). On the other hand, there were no significant differences in decline of mean power in the concentric phase of squats on the Bosu ball and on stable support base (11.4 and 9.6%, respectively). It may be concluded that power outputs during resistance exercises is more profoundly compromised under unstable than under stable conditions, and this effect is more evident for barbell chest presses on the Swiss ball than for barbell squats on the Bosu ball. These findings have to be taken into account when instability resistance exercises are implemented into the training program, namely, for sports that require production of maximal force in short time.

  1. W-band GaN MMIC PA with 257 mW output power at 86.5 GHz

    NASA Astrophysics Data System (ADS)

    Peng, Xu; Xubo, Song; Yuanjie, Lü; Yuangang, Wang; Shaobo, Dun; Jiayun, Yin; Yulong, Fang; Guodong, Gu; Zhihong, Feng; Shujun, Cai

    2015-08-01

    A three-stage W-band GaN monolithic microwave integrated circuit power amplifier (MMIC PA) is reported. In order to manage coupling effects between all the parts of the W-band MMIC, all matching and bias networks have been first optimized using circuit simulating software and then systematically simulated on 3D full-wave electromagnetic simulator. The fabricated MMIC PA achieves a 257 mW output power at 86.5 GHz in continuous-wave mode, with an associated power added efficiency of 5.4% and an associated power gain of 6.1 dB. The power density is 459 mW/mm. Moreover, the MMIC PA offers over 100 mW in the 83-90 GHz bandwidth. Those performances were measured at drain bias of 12 V. Project supported by the National Natural Science Foundation of China (No. 61306113).

  2. 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.

  3. Actively mode-locked Tm(3+)-doped silica fiber laser with wavelength-tunable, high average output power.

    PubMed

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

    2015-04-01

    A diode-pumped, actively mode-locked high-power thulium (Tm3+)-doped double-clad silica fiber laser is demonstrated, providing an average output power in mode-locked (continuous wave) operation of 53 W (72 W) with a slope efficiency of 34% (38%). Mode-locking in the 6th-harmonic order was obtained by an acousto-optic modulator driven at 66 MHz without dispersion compensation. The shortest measured output pulse width was 200 ps. Owing to a diffraction grating as cavity end mirror, the central wavelength could be tuned from 1.95 to 2.13 μm. The measured beam quality in mode-locked and continuous wave operation has been close to the diffraction limit. PMID:25831360

  4. Edge-facet pumped, multi-aperture, thin-disk laser geometry for very high average power output scaling

    DOEpatents

    Zapata, Luis E.

    2004-12-21

    The average power output of a laser is scaled, to first order, by increasing the transverse dimension of the gain medium while increasing the thickness of an index matched light guide proportionately. Strategic facets cut at the edges of the laminated gain medium provide a method by which the pump light introduced through edges of the composite structure is trapped and passes through the gain medium repeatedly. Spontaneous emission escapes the laser volume via these facets. A multi-faceted disk geometry with grooves cut into the thickness of the gain medium is optimized to passively reject spontaneous emission generated within the laser material, which would otherwise be trapped and amplified within the high index composite disk. Such geometry allows the useful size of the laser aperture to be increased, enabling the average laser output power to be scaled.

  5. Actively mode-locked Tm(3+)-doped silica fiber laser with wavelength-tunable, high average output power.

    PubMed

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

    2015-04-01

    A diode-pumped, actively mode-locked high-power thulium (Tm3+)-doped double-clad silica fiber laser is demonstrated, providing an average output power in mode-locked (continuous wave) operation of 53 W (72 W) with a slope efficiency of 34% (38%). Mode-locking in the 6th-harmonic order was obtained by an acousto-optic modulator driven at 66 MHz without dispersion compensation. The shortest measured output pulse width was 200 ps. Owing to a diffraction grating as cavity end mirror, the central wavelength could be tuned from 1.95 to 2.13 μm. The measured beam quality in mode-locked and continuous wave operation has been close to the diffraction limit.

  6. Phosphate single mode large mode area all-solid photonic crystal fiber with multi-watt output power

    SciTech Connect

    Wang, Longfei; He, Dongbing; Yu, Chunlei; Hu, Lili; Chen, Danping; Liu, Hui; Qiu, Jianrong

    2014-03-31

    An index-depressed active core, single-mode phosphate all-solid large-mode-area photonic crystal fiber (PCF) is theoretically investigated using full-vectorial finite difference approach and experimentally realized. The PCF has a maximum output power of 5.4 W and 31% slope efficiency. Single-mode operation is realized through PCFs with core diameters of 30, 35, and 40 μm, respectively. The beam quality is not degraded even at maximum output power. Our simulations and experiments reveal that the laser performance is significantly affected by the center-to-center distance between the two nearest rods Λ, the rod diameter d, and their ratio d/Λ, implying that much attention should be given in employing optimal parameters to achieve excellent laser performance.

  7. Simulation of traveling-wave output structures for high power rf tubes

    SciTech Connect

    Eppley, K.R.

    1993-04-01

    Travelling wave output structures can in principle provide higher efficiency and lower surface gradients than a single output cavity. We discuss simulations of TW structures designed for X-band klystrons to be used in the SLAC NLC. The PIC Code CONDOR calculated efficiency over 50 percent for one such circuit. When the circuit was built in the SLAC XC7 klystron, the match was so poor that it had to be modified. When tested, the tube produced less than half the efficiency calculated. We subsequently found significant differences between the field distribution calculated by CONDOR versus that from the 3-D code MAFIA. We have now developed a procedure which gives much better agreement between the 2D and 3-D models. We use a {pi}/2 disk-loaded structure, with the waveguide coupling to an output cavity through an iris, rather than directly to the drift tube as in the XC7. The disk radii are tapered to produce an approximately constant gradient. The output coupling is adjusted to match to a uniform structure replicating the cell before the waveguide. The simulations predict 75 MW, 49 percent efficiency, with peak surface fields of 73 MV/m. from a 440 kV, 350 amp beam at 11.424 GHz.

  8. Numerical predictions versus experimental findings on the power-harvesting output of a NiMnGa alloy

    NASA Astrophysics Data System (ADS)

    Nelson, Isaac; Dikes, Jason; Feigenbaum, Heidi; Ciocanel, Constantin

    2014-03-01

    Magnetic shape memory alloys (MSMAs) can display up to 10% recoverable strain in response to the application of a magnetic field or compressive mechanical stress. The amount of recoverable strain depends on the amount and direction of the applied stress and magnetic field as well as manufacturing, chemical composition, and training of the material. Due to their relatively large strains and fast response, MSMAs are suitable for a wide range of applications, including power harvesting, sensing, and actuation. The response of MSMAs is primarily driven by the reorientation of martensite variants. Power harvesting is possible due to this reorientation process and the accompanying change in material's magnetization, which can be changed into an electric potential/voltage using a pick-up coil placed around (or on the side of) the specimen. The magnitude of the output voltage depends on the number of turns of the pick-up coil, the amplitude of the reorientation strain, the magnitude and direction of the biased magnetic field, and the frequency at which the reorientation occurs. This paper focuses on the ability of a two dimensional constitutive model, developed by the group to capture the magnetomechanical response of MSMAs under general two dimensional loading conditions, to predict the power harvesting output of a Ni2MnGa specimen. Comparison between model predictions of voltage output and experimental measurements of the same indicate that, while the model is able to replicate the stress-strain response of the material during power harvesting, it is unable to accurately predict the magnitude of the experimentally measured voltage output. This indicates that additional features still need to be included in the model to better capture the change in magnetization that occurs during variant reorientation.

  9. A high-power low-temperature air plasma generator with a divergent channel of the output electrode

    NASA Astrophysics Data System (ADS)

    Gadzhiev, M. Kh.; Isakaev, E. Kh.; Tyuftyaev, A. S.; Yusupov, D. I.

    2016-01-01

    We have developed and studied a powerful high-enthalpy (H ≥ 20 kJ/g) air plasma jet generator with a divergent channel of the output electrode, which belongs to the class of dc plasmatrons with a thermionic cathode. The plasma generator possesses an efficiency of about 80% and ensures the formation of slightly divergent (2± = 12°) plasma jet with diameter D = 50 mm and a mass-average temperature of 6000-9000 K.

  10. Maximum power output and load matching of a phosphoric acid fuel cell-thermoelectric generator hybrid system

    NASA Astrophysics Data System (ADS)

    Chen, Xiaohang; Wang, Yuan; Cai, Ling; Zhou, Yinghui

    2015-10-01

    Based on the current models of phosphoric acid fuel cells (PAFCs) and thermoelectric generators (TGs), a new hybrid system is proposed, in which the effects of multi-irreversibilities resulting from the activation, concentration, and ohmic overpotentials in the PAFC, Joule heat and heat leak in the TG, finite-rate heat transfer between the TG and the heat reservoirs, and heat leak from the PAFC to the environment are taken into account. Expressions for the power output and efficiency of the PAFC, TG, and hybrid system are analytically derived and directly used to discuss the performance characteristics of the hybrid system. The optimal relationship between the electric currents in the PAFC and TG is obtained. The maximum power output is numerically calculated. It is found that the maximum power output density of the hybrid system will increase about 150 Wm-2, compared with that of a single PAFC. The problem how to optimally match the load resistances of two subsystems is discussed. Some significant results for practical hybrid systems are obtained.

  11. Enhancing photovoltaic output power by 3-band spectrum-splitting and concentration using a diffractive micro-optic

    DOE PAGES

    Mohammad, Nabil; Wang, Peng; Friedman, Daniel J.; Menon, Rajesh

    2014-09-17

    We report the enhancement of photovoltaic output power by separating the incident spectrum into 3 bands, and concentrating these bands onto 3 different photovoltaic cells. The spectrum-splitting and concentration is achieved via a thin, planar micro-optical element that demonstrates high optical efficiency over the entire spectrum of interest. The optic (which we call a polychromat) was designed using a modified version of the direct-binary-search algorithm. The polychromat was fabricated using grayscale lithography. Rigorous optical characterization demonstrates excellent agreement with simulation results. Electrical characterization of the solar cells made from GaInP, GaAs and Si indicate increase in the peak output powermore » density of 43.63%, 30.84% and 30.86%, respectively when compared to normal operation without the polychromat. This represents an overall increase of 35.52% in output power density. As a result, the potential for cost-effective large-area manufacturing and for high system efficiencies makes our approach a strong candidate for low cost solar power.« less

  12. Improved output power of GaN-based ultraviolet light-emitting diodes with sputtered AlN nucleation layer

    NASA Astrophysics Data System (ADS)

    Chiu, C. H.; Lin, Y. W.; Tsai, M. T.; Lin, B. C.; Li, Z. Y.; Tu, P. M.; Huang, S. C.; Hsu, Earl; Uen, W. Y.; Lee, W. I.; Kuo, H. C.

    2015-03-01

    In this work, the ultraviolet light-emitting diodes (UV-LEDs) at 380 nm were grown on patterned sapphire substrate (PSS) by atmospheric pressure metal organic chemical vapor deposition (AP-MOCVD). A sputtered AlN nucleation layer was utilized on the PSS to enhance the quality of the epitaxial layer. By using high-resolution X-ray diffraction, the full-width at half-maximum of the rocking curve shows that the UV-LEDs with sputtered AlN nucleation layer had better crystalline quality when compared to conventional GaN nucleation samples. From the scanning electron microscope (SEM) and transmission electron microscopy (TEM) images, it can be observed that the tip and sidewall portion of the pattern was smooth using the sputtered AlN nucleation layer. The threading dislocation densities (TDDs) are reduced from 6×107 cm-2 to 2.5×107 cm-2 at the interface between the u-GaN layers for conventional and AlN PSS devices, respectively. As a result, a much higher light output power was achieved. The light output power at an injection current of 20 mA was enhanced by 30%. Further photoluminescence (PL) measurement and numerical simulation confirm that this increase of output power can be attributed to the improvement of material quality and light extraction.

  13. Advanced Condenser Boosts Geothermal Power Plant Output (Fact Sheet), The Spectrum of Clean Energy Innovation

    SciTech Connect

    Not Available

    2010-12-01

    When power production at The Geysers geothermal power complex began to falter, the National Renewable Energy Laboratory (NREL) stepped in, developing advanced condensing technology that dramatically boosted production efficiency - and making a major contribution to the effective use of geothermal power. NREL developed advanced direct-contact condenser (ADCC) technology to condense spent steam more effectively, improving power production efficiency in Unit 11 by 5%.

  14. Evaluation of a ducted-fan power plant designed for high output and good cruise fuel economy

    NASA Technical Reports Server (NTRS)

    Behun, M; Rom, F E; Hensley, R V

    1950-01-01

    Theoretical analysis of performance of a ducted-fan power plant designed both for high-output, high-altitude operation at low supersonic Mach numbers and for good fuel economy at lower fight speeds is presented. Performance of ducted fan is compared with performance (with and without tail-pipe burner) of two hypothetical turbojet engines. At maximum power, the ducted fan has propulsive thrust per unit of frontal area between thrusts obtained by turbojet engines with and without tail-pipe burners. At cruise, the ducted fan obtains lowest thrust specific fuel consumption. For equal maximum thrusts, the ducted fan obtains cruising flight duration and range appreciably greater than turbojet engines.

  15. Monolithic thulium fiber laser with 567  W output power at 1970  nm.

    PubMed

    Walbaum, Till; Heinzig, Matthias; Schreiber, Thomas; Eberhardt, Ramona; Tünnermann, Andreas

    2016-06-01

    We report on a monolithic thulium fiber laser with 567 W output power at 1970 nm which, to the best of our knowledge, is the highest power reported so far directly from a thulium oscillator. This is achieved by optimization of the splice parameters for the active fiber (minimizing signal light in the fiber cladding) and direct water cooling. Dual transverse mode operation is visible from the optical spectrum and can be deduced from the measured beam quality of M2=2.6. PMID:27244432

  16. An upper limit to the electrodynamic power output from a thin accretion disk around a black hole

    NASA Technical Reports Server (NTRS)

    Park, Seok Jae; Vishniac, Ethan T.

    1994-01-01

    We examine the electrodynamic power output from a thin accretion disk surrounding a Kerr black hole. We derive an upper limit for the total power. We find that this limit is only moderately sensitive to most of the relativistic correction factors. In fact, this limit is less sensitive to the change in the black hole spin than one would expect from the change in the inner radius of the accretion disk. The disk around a rapidly rotating black hole will produce more nonthermal radiation than a similar disk around a slowly rotating black hole of identical mass, but the difference is only a factor of approximately 1.7.

  17. Acoustic noise from tandem wind rotors of intelligent wind power unit

    NASA Astrophysics Data System (ADS)

    Kubo, Koichi; Mihara, Nobuhiko; Enishi, Akira; Kanemoto, Toshiaki

    2010-04-01

    The authors had invented the unique wind power unit composed of the large-sized front wind rotor, the small-sized rear wind rotor and the peculiar generator with the inner and the outer rotational armatures without the conventional stator. This unit is called "Intelligent Wind Power Unit" by the authors. The front and the rear wind rotors drive the inner and the outer armatures, respectively, while the rotational torque is counter-balanced between both armatures/wind rotors. This paper discusses experimentally the acoustic noise from the front and the rear wind rotors. The acoustic noise, in the counter-rotating operation, is induced mainly from the flow interaction between both rotors, and has the dominant power spectrum density at the frequency of the blade passing interaction. The noise is caused mainly from the turbulent fluctuation due to the flow separation on the blade, when the rear wind rotor stops or rotates in the same direction as the front wind rotor.

  18. Plasma and cyclotron frequency effects on output power of the plasma wave-pumped free-electron lasers

    NASA Astrophysics Data System (ADS)

    Zolghadr, S. H.; Jafari, S.; Raghavi, A.

    2016-05-01

    Significant progress has been made employing plasmas in the free-electron lasers (FELs) interaction region. In this regard, we study the output power and saturation length of the plasma whistler wave-pumped FEL in a magnetized plasma channel. The small wavelength of the whistler wave (in sub-μm range) in plasma allows obtaining higher radiation frequency than conventional wiggler FELs. This configuration has a higher tunability by adjusting the plasma density relative to the conventional ones. A set of coupled nonlinear differential equations is employed which governs on the self-consistent evolution of an electromagnetic wave. The electron bunching process of the whistler-pumped FEL has been investigated numerically. The result reveals that for a long wiggler length, the bunching factor can appreciably change as the electron beam propagates through the wiggler. The effects of plasma frequency (or plasma density) and cyclotron frequency on the output power and saturation length have been studied. Simulation results indicate that with increasing the plasma frequency, the power increases and the saturation length decreases. In addition, when density of background plasma is higher than the electron beam density (i.e., for a dense plasma channel), the plasma effects are more pronounced and the FEL-power is significantly high. It is also found that with increasing the strength of the external magnetic field frequency, the power decreases and the saturation length increases, noticeably.

  19. Core-pumped single-frequency fiber amplifier with an output power of 158  W.

    PubMed

    Theeg, Thomas; Ottenhues, Christoph; Sayinc, Hakan; Neumann, Jörg; Kracht, Dietmar

    2016-01-01

    Single-frequency laser sources at a wavelength of 1 μm are typically scaled in power with Ytterbium-doped double-clad fiber amplifiers. The main limitations are stimulated Brillouin scattering, transversal mode instabilities and, from a technical point of view, the degree of fiber integration for a rugged setup. Addressing these limitations, we propose an alternative high-power single-frequency amplifier concept based on core pumping. A nonplanar ring oscillator with 2 W of output power at 1 kHz spectral linewidth was scaled by a fiber amplifier up to a power of 158 W without any indication of stimulated Brillouin scattering-using a standard Ytterbium-doped single-mode fiber with a mode field area of only ∼100  μm2. A short active fiber length and a strong temperature gradient along the gain fiber yield to efficient suppression of stimulated Brillouin scattering. For deeper understanding of the Brillouin scattering mitigation mechanism, we studied the Brillouin gain spectra with a Fabry-Perot interferometer at different output power levels of the fiber amplifier. PMID:26696145

  20. Power-ratio tunable dual-wavelength laser using linearly variable Fabry-Perot filter as output coupler.

    PubMed

    Wang, Xiaozhong; Wang, Zhongfa; Bu, Yikun; Chen, Lujian; Cai, Guoxiong; Huang, Wencai; Cai, Zhiping; Chen, Nan

    2016-02-01

    For a linearly variable Fabry-Perot filter, the peak transmission wavelengths change linearly with the transverse position shift of the substrate. Such a Fabry-Perot filter is designed and fabricated and used as an output coupler of a c-cut Nd:YVO4 laser experimentally in this paper to obtain a 1062 and 1083 nm dual-wavelength laser. The peak transmission wavelengths are gradually shifted from 1040.8 to 1070.8 nm. The peak transmission wavelength of the Fabry-Perot filter used as the output coupler for the dual-wavelength laser is 1068 nm and resides between 1062 and 1083 nm, which makes the transmissions of the desired dual wavelengths change in opposite slopes with the transverse shift of the filter. Consequently, powers of the two wavelengths change in opposite directions. A branch power, oppositely tunable 1062 and 1083 nm dual-wavelength laser is successfully demonstrated. Design principles of the linear variable Fabry-Perot filter used as an output coupler are discussed. Advantages of the method are summarized.

  1. Downscaling Solar Power Output to 4-Seconds for Use in Integration Studies (Presentation)

    SciTech Connect

    Hummon, M.; Weekley, A.; Searight, K.; Clark, K.

    2013-10-01

    High penetration renewable integration studies require solar power data with high spatial and temporal accuracy to quantify the impact of high frequency solar power ramps on the operation of the system. Our previous work concentrated on downscaling solar power from one hour to one minute by simulation. This method used clearness classifications to categorize temporal and spatial variability, and iterative methods to simulate intra-hour clearness variability. We determined that solar power ramp correlations between sites decrease with distance and the duration of the ramp, starting at around 0.6 for 30-minute ramps between sites that are less than 20 km apart. The sub-hour irradiance algorithm we developed has a noise floor that causes the correlations to approach ~0.005. Below one minute, the majority of the correlations of solar power ramps between sites less than 20 km apart are zero, and thus a new method to simulate intra-minute variability is needed. These intra-minute solar power ramps can be simulated using several methods, three of which we evaluate: a cubic spline fit to the one-minute solar power data; projection of the power spectral density toward the higher frequency domain; and average high frequency power spectral density from measured data. Each of these methods either under- or over-estimates the variability of intra-minute solar power ramps. We show that an optimized weighted linear sum of methods, dependent on the classification of temporal variability of the segment of one-minute solar power data, yields time series and ramp distributions similar to measured high-resolution solar irradiance data.

  2. Downscaling Solar Power Output to 4-Seconds for Use in Integration Studies: Preprint

    SciTech Connect

    Hummon, M.; Weekley, A.; Searight, K.; Clark, K.

    2013-10-01

    High penetration renewable integration studies require solar power data with high spatial and temporal accuracy to quantify the impact of high frequency solar power ramps on the operation of the system. Our previous work concentrated on downscaling solar power from one hour to one minute by simulation. This method used clearness classifications to categorize temporal and spatial variability, and iterative methods to simulate intra-hour clearness variability. We determined that solar power ramp correlations between sites decrease with distance and the duration of the ramp, starting at around 0.6 for 30-minute ramps between sites that are less than 20 km apart. The sub-hour irradiance algorithm we developed has a noise floor that causes the correlations to approach ~0.005. Below one minute, the majority of the correlations of solar power ramps between sites less than 20 km apart are zero, and thus a new method to simulate intra-minute variability is needed. These intra-minute solar power ramps can be simulated using several methods, three of which we evaluate: a cubic spline fit to the one-minute solar power data; projection of the power spectral density toward the higher frequency domain; and average high frequency power spectral density from measured data. Each of these methods either under- or over-estimates the variability of intra-minute solar power ramps. We show that an optimized weighted linear sum of methods, dependent on the classification of temporal variability of the segment of one-minute solar power data, yields time series and ramp distributions similar to measured high-resolution solar irradiance data.

  3. 75 FR 3985 - Trade Regulation Rule Relating to Power Output Claims for Amplifiers Utilized in Home...

    Federal Register 2010, 2011, 2012, 2013, 2014

    2010-01-26

    ... power ratings of multichannel home theater amplifiers. 65 FR 80798 (Dec. 22, 2000). The SNPR elicited... testing multichannel amplifiers . 67 FR 1915 (Jan. 15, 2002). Although CEA subsequently issued a standard... industry had not agreed on a power rating standard for multichannel amplifiers. 72 FR 13052 (March 20,...

  4. Human Muscle Power Output during Upper- and Lower-Body Exercises.

    ERIC Educational Resources Information Center

    Siegel, Judith A.; Gilders, Roger M.; Staron, Robert S.; Hagerman, Fredrick C.

    2002-01-01

    Evaluated the use of traditional resistance training equipment in measuring muscular power, measuring the velocity of movement through a measured distance during maximal effort lifts using a Smith rack. Data collected on male volunteers indicated that this method of evaluating muscle power was reliable, although it was not predictive of muscle…

  5. Monitoring Thermal Fatigue Damage In Nuclear Power Plant Materials Using Acoustic Emission

    SciTech Connect

    Meyer, Ryan M.; Ramuhalli, Pradeep; Watson, Bruce E.; Pitman, Stan G.; Roosendaal, Timothy J.; Bond, Leonard J.

    2012-04-26

    Proactive aging management of nuclear power plant passive components requires technologies to enable monitoring and accurate quantification of material condition at early stages of degradation (i.e., pre-macrocrack). Acoustic emission (AE) is well-suited to continuous monitoring of component degradation and is proposed as a method to monitor degradation during accelerated thermal fatigue tests. A key consideration is the ability to separate degradation responses from external sources such as water spray induced during thermal fatigue testing. Water spray provides a significant background of acoustic signals, which can overwhelm AE signals caused by degradation. Analysis of AE signal frequency and energy is proposed in this work as a means for separating degradation signals from background sources. Encouraging results were obtained by applying both frequency and energy filters to preliminary data. The analysis of signals filtered using frequency and energy provides signatures exhibiting several characteristics that are consistent with degradation accumulation in materials. Future work is planned to enable verification of the efficacy of AE for thermal fatigue crack initiation detection. While the emphasis has been placed on the use of AE for crack initiation detection during accelerated aging tests, this work also has implications with respect to the use of AE as a primary tool for early degradation monitoring in nuclear power plant materials. The development of NDE tools for characterization of aging in materials can also benefit from the use of a technology such as AE which can continuously monitor and detect crack initiation during accelerated aging tests.

  6. High efficiency, diode pumped Nd:YAG ceramics slab laser with 230 W continuous-wave output power.

    PubMed

    Lapucci, Antonio; Ciofini, Marco; Vannoni, Maurizo; Sordini, Andrea

    2012-06-20

    Diode pumped zig-zag slab lasers are widely adopted for continuous-wave high power or pulsed high energy applications. Recently [J. Eur. Opt. Soc.-Rapid 6, 11041 (2011)] we started to investigate a new thin slab format in which pumping radiation input is obtained through the thin lateral faces (edge pumping) and the beam propagation takes place bouncing on these same lateral faces ("edge zig-zag"). We report on the optimized operation of a ceramic Nd:YAG laser, based on this geometry, extracting 230 W at a 43% output power to diode power conversion efficiency. Thorough investigation of the thermal lens effect allows us to analyze the optical cavity and thus to define the main aspects limiting the present laser configuration.

  7. Low power low temperature poly-Si thin-film transistor shift register with DC-type output driver

    NASA Astrophysics Data System (ADS)

    Song, Seok-Jeong; Kim, Byung Hoon; Jang, Jin; Nam, Hyoungsik

    2015-09-01

    This paper demonstrates a low power DC-type low temperature poly-Si (LTPS) thin-film transistor (TFT) shift register that consists of nine TFTs and one bootstrapping capacitor. The proposed circuit connects large size pull-up TFTs of output drivers to positive supply instead of alternating clock signals in order to reduce substantially the power consumption of clock drivers. The SPICE simulation ensures that the variable overlap intervals can be programmed by the delay between clock signals and the overall power consumption of a DC-type circuit can be reduced to 45% of an AC-type one for a full-HD display. The operation of a proposed structure is also verified with a fabricated 16-stage gate driver.

  8. Multiple output power supply circuit for an ion engine with shared upper inverter

    NASA Technical Reports Server (NTRS)

    Cardwell, Jr., Gilbert I. (Inventor); Phelps, Thomas K. (Inventor)

    2001-01-01

    A power supply circuit for an ion engine suitable for a spacecraft is coupled to a bus having a bus input and a bus return. The power supply circuit has a first primary winding of a first transformer. An upper inverter circuit is coupled to the bus input and the first primary winding. The power supply circuit further includes a first lower inverter circuit coupled to the bus return and the first primary winding. The second primary winding of a second transformer is coupled to the upper inverter circuit. A second lower inverter circuit is coupled to the bus return and the second primary winding.

  9. Local and regional effects of large scale atmospheric circulation patterns on winter wind power output in Western Europe

    NASA Astrophysics Data System (ADS)

    Zubiate, Laura; McDermott, Frank; Sweeney, Conor; O'Malley, Mark

    2014-05-01

    Recent studies (Brayshaw, 2009, Garcia-Bustamante, 2010, Garcia-Bustamante, 2013) have drawn attention to the sensitivity of wind speed distributions and likely wind energy power output in Western Europe to changes in low-frequency, large scale atmospheric circulation patterns such as the North Atlantic Oscillation (NAO). Wind speed variations and directional shifts as a function of the NAO state can be larger or smaller depending on the North Atlantic region that is considered. Wind speeds in Ireland and the UK for example are approximately 20 % higher during NAO + phases, and up to 30 % lower during NAO - phases relative to the long-term (30 year) climatological means. By contrast, in southern Europe, wind speeds are 15 % lower than average during NAO + phases and 15 % higher than average during NAO - phases. Crucially however, some regions such as Brittany in N.W. France have been identified in which there is negligible variability in wind speeds as a function of the NAO phase, as observed in the ERA-Interim 0.5 degree gridded reanalysis database. However, the magnitude of these effects on wind conditions is temporally and spatially non-stationary. As described by Comas-Bru and McDermott (2013) for temperature and precipitation, such non-stationarity is caused by the influence of two other patterns, the East Atlantic pattern, (EA), and the Scandinavian pattern, (SCA), which modulate the position of the NAO dipole. This phenomenon has also implications for wind speeds and directions, which has been assessed using the ERA-Interim reanalysis dataset and the indices obtained from the PC analysis of sea level pressure over the Atlantic region. In order to study the implications for power production, the interaction of the NAO and the other teleconnection patterns with local topography was also analysed, as well as how these interactions ultimately translate into wind power output. The objective is to have a better defined relationship between wind speed and power

  10. Shear-horizontal surface acoustic wave phononic device with high density filling material for ultra-low power sensing applications

    SciTech Connect

    Richardson, M.; Bhethanabotla, V. R.; Sankaranarayanan, S. K. R. S.

    2014-06-23

    Finite element simulations of a phononic shear-horizontal surface acoustic wave (SAW) sensor based on ST 90°-X Quartz reveal a dramatic reduction in power consumption. The phononic sensor is realized by artificially structuring the delay path to form an acoustic meta-material comprised of a periodic microcavity array incorporating high-density materials such as tantalum or tungsten. Constructive interference of the scattered and secondary reflected waves at every microcavity interface leads to acoustic energy confinement in the high-density regions translating into reduced power loss. Tantalum filled cavities show the best performance while tungsten inclusions create a phononic bandgap. Based on our simulation results, SAW devices with tantalum filled microcavities were fabricated and shown to significantly decrease insertion loss. Our findings offer encouraging prospects for designing low power, highly sensitive portable biosensors.

  11. Effects of Active Versus Passive Recovery on Power Output During Repeated Bouts of Short Term, High Intensity Exercise

    PubMed Central

    Connolly, Declan AJ.; Brennan, Kevin M.; Lauzon, Christie D.

    2003-01-01

    ATP repletion following exhaustive exercise is approximated to be 90-95% complete in 3 minutes, and is crucial in the performance of short duration, high intensity work. Few studies appear to have used this 3-minute interval in the investigation of recovery modes, blood lactate accumulation and power output. Thus, our aim was to investigate changes in peak power (PP), average power (AP) and blood lactate during repeated bouts of high intensity, short duration cycling, comprising active and passive recovery modes lasting 3 minutes. Seven male cyclists (age 21.8±3.3 yrs, mass 73.0±3.8kgs, height 177.3±3.4cm) performed both an active (3 min at 80rpm & 1kg resistance) and a passive recovery (no work between bouts) protocol. Following a warm-up, subjects performed six 15-second maximal sprints against a fixed workload of 5.5kg. Mean PP across the six trials was 775±11.2Watts (W) and 772±33.4W for active and passive protocols respectively; whereas mean AP was 671±26.4W and 664±10.0W, respectively. Neither was significantly different. There was a significant difference within trials for both peak power and average power (p<0.05), with both values decreasing over time. However, the decrease was significantly smaller for both PP and AP values during the active recovery protocol (p<0.05). In the current study, variation in power output cannot be explained by lactate values, as values did not differ between the active and passive protocol (p=0.37). Lactate values did differ significantly between trials within protocols (p<0.05). The results of this study suggest that an active recovery of 3 minutes between high intensity, short duration exercise bouts significantly increases PP and AP compared to a passive recovery, irrespective of changes in blood lactate levels. PMID:24616610

  12. Rechargeable lithium battery for use in applications requiring a low to high power output

    DOEpatents

    Bates, John B.

    1997-01-01

    Rechargeable lithium batteries which employ characteristics of thin-film batteries can be used to satisfy power requirements within a relatively broad range. Thin-film battery cells utilizing a film of anode material, a film of cathode material and an electrolyte of an amorphous lithium phosphorus oxynitride can be connected in series or parallel relationship for the purpose of withdrawing electrical power simultaneously from the cells. In addition, such battery cells which employ a lithium intercalation compound as its cathode material can be connected in a manner suitable for supplying power for the operation of an electric vehicle. Still further, by incorporating within the battery cell a relatively thick cathode of a lithium intercalation compound, a relatively thick anode of lithium and an electrolyte film of lithium phosphorus oxynitride, the battery cell is rendered capable of supplying power for any of a number of consumer products, such as a laptop computer or a cellular telephone.

  13. Rechargeable lithium battery for use in applications requiring a low to high power output

    DOEpatents

    Bates, John B.

    1996-01-01

    Rechargeable lithium batteries which employ characteristics of thin-film batteries can be used to satisfy power requirements within a relatively broad range. Thin-film battery cells utilizing a film of anode material, a film of cathode material and an electrolyte of an amorphorus lithium phosphorus oxynitride can be connected in series or parallel relationship for the purpose of withdrawing electrical power simultaneously from the cells. In addition, such battery cells which employ a lithium intercalation compound as its cathode material can be connected in a manner suitable for supplying power for the operation of an electric vehicle. Still further, by incorporating within the battery cell a relatively thick cathode of a lithium intercalation compound, a relatively thick anode of lithium and an electrolyte film of lithium phosphorus oxynitride, the battery cell is rendered capable of supplying power for any of a number of consumer products, such as a laptop computer or a cellular telephone.

  14. Acoustical gas core reactor with MHD power generation for burst power in a bimodal system

    NASA Astrophysics Data System (ADS)

    Dugan, E. T.; Jacobs, A. M.; Oliver, C. C.; Lear, W. E., Jr.

    Research is being conducted on gas core reactors for space nuclear power to establish the scientific feasibility and engineering validation of a reactor and energy conversion system that can significantly improve specific power, dynamic performance and system efficiency. Rapid achievement of burst mode (GWe) operation at core power densities of 1 kW/mL and reactor masses of a kg/MWt are research objectives; coupled with MHD conversion, system efficiencies of 40 percent for open cycle operation and heat rejection temperatures of 1500 K or higher for closed cycle operation are anticipated. The design of the gas core reactor/MHD generator configuration to directly produce pulsed electrical power, thereby alleviating external power conditioning requirements, is also a research objective.

  15. Multi-Purpose Low Voltage Dual Output DC-DC Converter For 100V Power Bus Telecom Platform

    NASA Astrophysics Data System (ADS)

    Galiana, D.; Mollard, J. M.

    2011-10-01

    The decreasing supply voltages of digital electronic and high speed ADC (Analog to Digital Converter) and DAC (Digital to Analog Converter) require flexible and high current secondary power distribution system. In the frame of the Inmarsat I-XL program, a 12 kW geomobile SatCom satellite, with 100 V regulated power bus, a multi purpose dual output converter was developed for the payload processor as a building block. After a short introduction on the main performance requirements, the baseline architecture is presented. The main drivers of the architecture are reliability, adjustability, radiation tolerant and single event free, volume and mass. The combination of all these constraints highlights the need of significant breakthrough in various domains. Many research results related to packaging and power electronic topics are brought up. These results directly drive the adopted solution presented in the next step followed by a description of the integration of the defined building block in the Inmarsat I-XL payload IP (Integrated Processor). Finally, the main electrical performances such as output ripple and spikes, load step transient and stability are summarized.

  16. Improvement of Power Efficiency for Underwater Acoustic Communication Using Orthogonal Signal Division Multiplexing over Multiple Transducers

    NASA Astrophysics Data System (ADS)

    Ebihara, Tadashi

    2013-07-01

    In underwater acoustic (UWA) communication, power efficiency is one of the important characteristics. This paper is about multistream transmission using orthogonal signal division multiplexing (OSDM) as a technique to increase power efficiency. In this work, the performance of multistream transmission using OSDM is evaluated both experimentally in a test tank and by numerical simulation. Through this study, it is confirmed that the multistream transmission scheme is effective in enhancing the power efficiency compared with the single-stream transmission using higher order modulation. Moreover, the performance of multistream transmission using OSDM is compared with the existing scheme, multistream transmission using orthogonal frequency division multiplexing (OFDM). The obtained results suggest that multistream transmission using OSDM is attractive because it can achieve the same bit-error rate (BER) and the same data rate with less power of the signal, compared with the reference. Although the calculation cost of OSDM in the receiver remains as an issue, multistream transmission using OSDM may contribute to high-speed UWA communication because of its excellent power efficiency.

  17. Muscle contractile properties as an explanation of the higher mean power output in marmosets than humans during jumping.

    PubMed

    Plas, Rogier L C; Degens, Hans; Meijer, J Peter; de Wit, Gerard M J; Philippens, Ingrid H C H M; Bobbert, Maarten F; Jaspers, Richard T

    2015-07-01

    The muscle mass-specific mean power output (PMMS,mean) during push-off in jumping in marmosets (Callithrix jacchus) is more than twice that in humans. In the present study it was tested whether this is attributable to differences in muscle contractile properties. In biopsies of marmoset m. vastus lateralis (VL) and m. gastrocnemius medialis (GM) (N=4), fibre-type distribution was assessed using fluorescent immunohistochemistry. In single fibres from four marmoset and nine human VL biopsies, the force-velocity characteristics were determined. Marmoset VL contained almost exclusively fast muscle fibres (>99.0%), of which 63% were type IIB and 37% were hybrid fibres, fibres containing multiple myosin heavy chains. GM contained 9% type I fibres, 44% type IIB and 47% hybrid muscle fibres. The proportions of fast muscle fibres in marmoset VL and GM were substantially larger than those reported in the corresponding human muscles. The curvature of the force-velocity relationships of marmoset type IIB and hybrid fibres was substantially flatter than that of human type I, IIA, IIX and hybrid fibres, resulting in substantially higher muscle fibre mass-specific peak power (PFMS,peak). Muscle mass-specific peak power output (PMMS,peak) values of marmoset whole VL and GM, estimated from their fibre-type distributions and force-velocity characteristics, were more than twice the estimates for the corresponding human muscles. As the relative difference in estimated PMMS,peak between marmosets and humans is similar to that of PMMS,mean during push-off in jumping, it is likely that the difference in in vivo mechanical output between humans and marmosets is attributable to differences in muscle contractile properties.

  18. Less is more: standard warm-up causes fatigue and less warm-up permits greater cycling power output.

    PubMed

    Tomaras, Elias K; MacIntosh, Brian R

    2011-07-01

    The traditional warm-up (WU) used by athletes to prepare for a sprint track cycling event involves a general WU followed by a series of brief sprints lasting ≥ 50 min in total. A WU of this duration and intensity could cause significant fatigue and impair subsequent performance. The purpose of this research was to compare a traditional WU with an experimental WU and examine the consequences of traditional and experimental WU on the 30-s Wingate test and electrically elicited twitch contractions. The traditional WU began with 20 min of cycling with a gradual intensity increase from 60% to 95% of maximal heart rate; then four sprints were performed at 8-min intervals. The experimental WU was shorter with less high-intensity exercise: intensity increased from 60% to 70% of maximal heart rate over 15 min; then just one sprint was performed. The Wingate test was conducted with a 1-min lead-in at 80% of optimal cadence followed by a Wingate test at optimal cadence. Peak active twitch torque was significantly lower after the traditional than experimental WU (86.5 ± 3.3% vs. 94.6 ± 2.4%, P < 0.05) when expressed as percentage of pre-WU amplitude. Wingate test performance was significantly better (P < 0.01) after experimental WU (peak power output = 1,390 ± 80 W, work = 29.1 ± 1.2 kJ) than traditional WU (peak power output = 1,303 ± 89 W, work = 27.7 ± 1.2 kJ). The traditional track cyclist's WU results in significant fatigue, which corresponds with impaired peak power output. A shorter and lower-intensity WU permits a better performance. PMID:21551012

  19. Terrestrial applications of FEP-encapsulated solar cell modules. [systems design and power output characteristics

    NASA Technical Reports Server (NTRS)

    Forestieri, A. F.; Ratajczak, A. F.

    1974-01-01

    FEP-encapsulated solar cell modules and arrays have been designed and built expressly for terrestrial applications. System design including solar cell array mechanical design and the approach to system sizing is outlined. Such solar cell systems have been installed at six sites. Individual modules have undergone marine environment tests. Results from seven months of operation indicate that system is meeting its electrical design requirements. No mechanical degradation has been reported. The array on Mammoth Mountain, California has been damaged by rime ice but shows no loss in electrical output. Marine environment tests on single modules have shown that elements of the module must be completely sealed by the FEP. Based on the limited test data available, the FEP-encapsulated solar cell module appears well suited to terrestrial applications.

  20. Anodic microbial community diversity as a predictor of the power output of microbial fuel cells.

    PubMed

    Stratford, James P; Beecroft, Nelli J; Slade, Robert C T; Grüning, André; Avignone-Rossa, Claudio

    2014-03-01

    The relationship between the diversity of mixed-species microbial consortia and their electrogenic potential in the anodes of microbial fuel cells was examined using different diversity measures as predictors. Identical microbial fuel cells were sampled at multiple time-points. Biofilm and suspension communities were analysed by denaturing gradient gel electrophoresis to calculate the number and relative abundance of species. Shannon and Simpson indices and richness were examined for association with power using bivariate and multiple linear regression, with biofilm DNA as an additional variable. In simple bivariate regressions, the correlation of Shannon diversity of the biofilm and power is stronger (r=0.65, p=0.001) than between power and richness (r=0.39, p=0.076), or between power and the Simpson index (r=0.5, p=0.018). Using Shannon diversity and biofilm DNA as predictors of power, a regression model can be constructed (r=0.73, p<0.001). Ecological parameters such as the Shannon index are predictive of the electrogenic potential of microbial communities.

  1. Study of the dependence of the specific output power of a copper chloride laser on the radial temperature profile of a gas plasma

    SciTech Connect

    Sadighi-Bonabi, R; Mohammadpour, R; Tavakoli, M; Soltanmoradi, F; Zand, M

    2007-04-30

    The design of a copper chloride laser is described, and the laser is optimised by studying the dependence of its output power on the buffer gas type. The voltage and current of the laser discharge at the optimum buffer gas pressure are measured. The influence of the diaphragm diameter on the specific output power is studied after optimisation of switch parameters. When an diaphragm producing the optimal temperature gradient in the laser gas-discharge tube, the record specific output power of 123 W L{sup -1} is obtained without any admixtures. (lasers)

  2. Single-walled carbon nanotubes as base material for THz photoconductive switching: a theoretical study from input power to output THz emission.

    PubMed

    Heshmat, Barmak; Pahlevaninezhad, Hamid; Beard, Matthew Craig; Papadopoulos, Chris; Darcie, Thomas Edward

    2011-08-01

    This paper studies the relation between photoexcitation of a single-walled carbon nanotube (SWNT) based device, and its THz output power in the context of THz photoconductive (PC) switching and THz photomixing. A detailed approach of calculating output THz power for such a device describes the effect of each parameter on the performance of the THz PC switch and highlights the design dependent achievable limits. A numerical assessment, with typical values for each parameter, shows that-subject to thermal stability of the device-SWNT based PC switch can improve the output power by almost two orders of magnitudes compared to conventional materials such as LT-GaAs.

  3. A Ka-band radial relativistic backward wave oscillator with GW-class output power

    NASA Astrophysics Data System (ADS)

    Zhu, Jiaxin; Zhang, Xiaoping; Dang, Fangchao

    2016-07-01

    A novel radial relativistic backward wave oscillator with a reflector is proposed and designed to generate GW-level high power microwaves at Ka-band. The segmented radial slow wave structure and the reflector are matched to enhance interaction efficiency. We choose the volume wave TM01 mode as the working mode due to the volume wave characteristic. The main structural parameters of the novel device are optimized by particle-in-cell simulation. High power microwaves with power of 2 GW and a frequency of 29.4 GHz are generated with 30% efficiency when the electron beam voltage is 383 kV, the beam current is 17 kA, and the guiding magnetic field is only 0.6 T. Simultaneously, the highest electric field in the novel Ka-band device is just about 960 kV/cm in second slow wave structure.

  4. Possibilities for avoiding strong variations of the electrical output power of wind energy systems

    NASA Astrophysics Data System (ADS)

    Cramer, G.

    1981-04-01

    The conversion of the kinetic energy of wind into electric power through wind powered converters by the primary energy of atmospheric circulation speed is discussed. It is suggested that wind powered generators which work with the supply network should avoid overloading the installation from wind performance caused by a fast change of the blade pitch. There are possibilities to achieve numerical comparison of the temporary storage performance of kinetic energy by application of rotating masses with flywheels, which allow for rotation speed variations. Through the feed of direct or alternate current in the rotor cycle form asynchronic machines with slip rings or through the influence of the slip performance a speed of variable duty on the network is accomplished.

  5. Tapered large-core 976 nm Yb-doped fiber laser with 10 W output power

    NASA Astrophysics Data System (ADS)

    Leich, M.; Jäger, M.; Grimm, S.; Hoh, D.; Jetschke, S.; Becker, M.; Hartung, A.; Bartelt, H.

    2014-04-01

    We report on a tapered large-core Yb fiber laser operating at 976 nm emission wavelength. It was realized using a high-numerical aperture large-core fiber with 126 μm core diameter, which was fabricated by powder-sinter technology and shows a very homogeneous step-index profile. The end of the fiber is tapered down to match a single-mode fiber containing a fiber Bragg grating. Using the benefits of core-pumping and the feedback of the spliced fiber Bragg grating, we achieved efficient pump light absorption and wavelength stable 976 nm lasing with single-mode performance. We could demonstrate 10 W laser power out of a 10 μm fiber core with a slope efficiency of 31% with respect to the launched pump power. The presented device is well-suited for fiber-coupled pumping of amplifiers for high peak power.

  6. Electrical power converter method and system employing multiple-output converters

    DOEpatents

    Beihoff, Bruce C.; Radosevich, Lawrence D.; Meyer, Andreas A.; Gollhardt, Neil; Kannenberg, Daniel G.

    2006-03-21

    A support may receive one or more power electronic circuits. The support may aid in removing heat from the circuits through fluid circulating through the support. The support, in conjunction with other packaging features may form a shield from both external EMI/RFI and from interference generated by operation of the power electronic circuits. Features may be provided to permit and enhance connection of the circuitry to external circuitry, such as improved terminal configurations. Modular units may be assembled that may be coupled to electronic circuitry via plug-in arrangements or through interface with a backplane or similar mounting and interconnecting structures.

  7. High-efficiency, high-output-power antiguide laser diode arrays

    NASA Technical Reports Server (NTRS)

    Mehuys, D.; Major, J. S., Jr.; Welch, D.; Scifres, D. R.

    1992-01-01

    Antiguide laser arrays have been fabricated and operated up to peak pulsed powers of 7.7 W in a beam with a full-width at half-maximum in the main lobe of 0.7 deg. Up to 0.7 W of continuous wave power is emitted into a radiation pattern 2.5 times the diffraction limit. By varying the temperature of the array to vary the operating wavelength of the device, the threshold gain condition of the array modes is altered, allowing thermal tuning of the far field of the device.

  8. Composite Thin-Disk Laser Scaleable to 100 kW Average Power Output and Beyond

    SciTech Connect

    Zapata, L.; Beach, R.; Payne, S.

    2000-06-01

    By combining newly developed technologies to engineer composite laser components with state of the art diode laser pump delivery technologies, we are in a position to demonstrate high beam quality, continuous wave, laser radiation at scaleable high average powers. The crucial issues of our composite thin disk laser technology were demonstrated during a successful first light effort. The high continuous wave power levels that are now within reach make this system of high interest to future DoD initiatives in solid-state laser technology for the laser weapon arena.

  9. The validity of power output recorded during exercise performance tests using a Kingcycle air-braked cycle ergometer when compared with an SRM powermeter.

    PubMed

    Balmer, J; Davison, R C; Coleman, D A; Bird, S R

    2000-04-01

    This study assessed the validity of power output recorded using an air-braked cycle ergometer (Kingcycle) when compared with a power measuring crankset (SRM). For part one of the study thirteen physically active subjects completed a continuous incremental exercise test (OBLA), for part two of the study twelve trained cyclists completed two tests; a maximal aerobic power test (MAP) and a 16.1 km time-trial (16.1 km TT). The following were compared; the peak power output (PPO) recorded for 1 min during MAP, the average power output for the duration of the time-trial and power output recorded during each stage of OBLA. For all tests, power output recorded using Kingcycle was significantly higher than SRM (P < 0.001). Ratio limits of agreement between SRM and Kingcycle for OBLA showed a bias (P < 0.00) of 0.90 (95%CI = 0.90-0.91) with a random error of X or / 1.07, and for PPO and 16.1 km TT ratio limits of agreement were 0.90 (95%CI = 0.88-0.92) X or / 1.07 and 0.92 (95% CI = 0.90-0.94) X or / 1.07, respectively. These data revealed that the Kingcycle ergometry system did not provide a valid measure of power output when compared with SRM.

  10. ACOUSTIC SCALE FROM THE ANGULAR POWER SPECTRA OF SDSS-III DR8 PHOTOMETRIC LUMINOUS GALAXIES

    SciTech Connect

    Seo, Hee-Jong; Ho, Shirley; White, Martin; Reid, Beth; Schlegel, David J.; Cuesta, Antonio J.; Padmanabhan, Nikhil; Ross, Ashley J.; Percival, Will J.; Nichol, Robert C.; Saito, Shun; De Putter, Roland; Eisenstein, Daniel J.; Xu Xiaoying; Skibba, Ramin; Schneider, Donald P.; Verde, Licia; Bizyaev, Dmitry; Brewington, Howard; Brinkmann, J.; and others

    2012-12-10

    We measure the acoustic scale from the angular power spectra of the Sloan Digital Sky Survey III (SDSS-III) Data Release 8 imaging catalog that includes 872, 921 galaxies over {approx}10,000 deg{sup 2} between 0.45 < z < 0.65. The extensive spectroscopic training set of the Baryon Oscillation Spectroscopic Survey luminous galaxies allows precise estimates of the true redshift distributions of galaxies in our imaging catalog. Utilizing the redshift distribution information, we build templates and fit to the power spectra of the data, which are measured in our companion paper, to derive the location of Baryon acoustic oscillations (BAOs) while marginalizing over many free parameters to exclude nearly all of the non-BAO signal. We derive the ratio of the angular diameter distance to the sound horizon scale D{sub A} (z)/r{sub s} = 9.212{sup +0.416}{sub -{sub 0.404}} at z = 0.54, and therefore D{sub A} (z) = 1411 {+-} 65 Mpc at z = 0.54; the result is fairly independent of assumptions on the underlying cosmology. Our measurement of angular diameter distance D{sub A} (z) is 1.4{sigma} higher than what is expected for the concordance {Lambda}CDM, in accordance to the trend of other spectroscopic BAO measurements for z {approx}> 0.35. We report constraints on cosmological parameters from our measurement in combination with the WMAP7 data and the previous spectroscopic BAO measurements of SDSS and WiggleZ. We refer to our companion papers (Ho et al.; de Putter et al.) for investigations on information of the full power spectrum.

  11. Thermal power output determination of 2 MW heat source by using of thermocouples

    NASA Astrophysics Data System (ADS)

    Holubcik, Michal; Vician, Peter; Palacka, Matej

    2016-06-01

    Experiment is an operation or procedure carried out under controlled conditions in order to discover an unknown effect or law, to test or establish a hypothesis, or to illustrate a known law. The most important part of the experiment is to evaluate the measured values. Measurement accuracy depends on a number of factors. Deviations of instruments cannot eliminate or influence if it is neglect the possibility of using more precise measuring equipment. Another way for the most accurate results can be calibration. Calibration allows achieve measurement values with relatively high accuracy using less precision instruments. The paper deals about the problematic of thermal power measurement accuracy. Thermal power was measured on heat source with nominal thermal power 2 MW by using direct calorimetric method. There were used ultrasonic flow meter and type K thermocouples. Type K thermocouples are not very suitable for these applications because of their low precision. The paper presents the possibility of using calibrated thermocouples for the thermal power measurement with acceptable accuracy.

  12. Method for reducing fuel cell output voltage to permit low power operation

    DOEpatents

    Reiser, Carl A.; Landau, Michael B.

    1980-01-01

    Fuel cell performance is degraded by recycling a portion of the cathode exhaust through the cells and, if necessary, also reducing the total air flow to the cells for the purpose of permitting operation below a power level which would otherwise result in excessive voltage.

  13. Comparison of treadmill and cycle ergometer measurements of force-velocity relationships and power output.

    PubMed

    Jaskólska, A; Goossens, P; Veenstra, B; Jaskólski, A; Skinner, J S

    1999-04-01

    Since body balance and weight-bearing factors present while running on the treadmill might cause additional muscle recruitment and thus could influence the force-velocity relationship and power, the present study was undertaken to find out whether the F-V and F-P relationships measured while running on the treadmill are different from the respective indices measured during cycling. On two separate occasions, 32 male subjects were tested using a series of 5 sec, all-out sprints against different braking forces on the Gymrol Sprint treadmill and on the Monark ergometer. The maximal peak power (PPmax) and maximal mean power (MPmax) were measured. The equation: EP = 0.5 maximal force (Fo) x0.5 maximal velocity (Vo) was used to calculate the estimated values of peak power (EPP) and mean power (EMP). The F-V relationship was linear in both cycle ergometer and treadmill measurements. PPmax, MPmax, EPP, and EMP values on the treadmill were lower than the respective values on the ergometer. EPP on the ergometer and on the treadmill, as well as EMP values on the ergometer, were slightly higher than the corresponding measured values of PPmax and MPmax. The levels of braking force at which PP, MP, PPmax, and MPmax were obtained were lower on the ergometer than on the treadmill. High correlation coefficients were found between PPmax, MPmax, EPP, and EMP measured on the ergometer and on the treadmill (r = 0.86, r = 0.84, r = 0.71, r = 0.78, respectively, P<0.01). In both tests, significant relationships between PPmax, MPmax, EPP, and EMP were observed. It is concluded that independent of the type of ergometry the force-velocity relationship is similar in the measured range of velocities which suggests that the number of muscle groups and joints engaged in movement are more important than body balance and weight-bearing factors present while running on a treadmill.

  14. Baryon acoustic oscillations in 2D: Modeling redshift-space power spectrum from perturbation theory

    NASA Astrophysics Data System (ADS)

    Taruya, Atsushi; Nishimichi, Takahiro; Saito, Shun

    2010-09-01

    We present an improved prescription for the matter power spectrum in redshift space taking proper account of both nonlinear gravitational clustering and redshift distortion, which are of particular importance for accurately modeling baryon acoustic oscillations (BAOs). Contrary to the models of redshift distortion phenomenologically introduced but frequently used in the literature, the new model includes the corrections arising from the nonlinear coupling between the density and velocity fields associated with two competitive effects of redshift distortion, i.e., Kaiser and Finger-of-God effects. Based on the improved treatment of perturbation theory for gravitational clustering, we compare our model predictions with the monopole and quadrupole power spectra of N-body simulations, and an excellent agreement is achieved over the scales of BAOs. Potential impacts on constraining dark energy and modified gravity from the redshift-space power spectrum are also investigated based on the Fisher-matrix formalism, particularly focusing on the measurements of the Hubble parameter, angular diameter distance, and growth rate for structure formation. We find that the existing phenomenological models of redshift distortion produce a systematic error on measurements of the angular diameter distance and Hubble parameter by 1%-2% , and the growth-rate parameter by ˜5%, which would become non-negligible for future galaxy surveys. Correctly modeling redshift distortion is thus essential, and the new prescription for the redshift-space power spectrum including the nonlinear corrections can be used as an accurate theoretical template for anisotropic BAOs.

  15. Baryon acoustic oscillations in 2D: Modeling redshift-space power spectrum from perturbation theory

    SciTech Connect

    Taruya, Atsushi; Nishimichi, Takahiro; Saito, Shun

    2010-09-15

    We present an improved prescription for the matter power spectrum in redshift space taking proper account of both nonlinear gravitational clustering and redshift distortion, which are of particular importance for accurately modeling baryon acoustic oscillations (BAOs). Contrary to the models of redshift distortion phenomenologically introduced but frequently used in the literature, the new model includes the corrections arising from the nonlinear coupling between the density and velocity fields associated with two competitive effects of redshift distortion, i.e., Kaiser and Finger-of-God effects. Based on the improved treatment of perturbation theory for gravitational clustering, we compare our model predictions with the monopole and quadrupole power spectra of N-body simulations, and an excellent agreement is achieved over the scales of BAOs. Potential impacts on constraining dark energy and modified gravity from the redshift-space power spectrum are also investigated based on the Fisher-matrix formalism, particularly focusing on the measurements of the Hubble parameter, angular diameter distance, and growth rate for structure formation. We find that the existing phenomenological models of redshift distortion produce a systematic error on measurements of the angular diameter distance and Hubble parameter by 1%-2%, and the growth-rate parameter by {approx}5%, which would become non-negligible for future galaxy surveys. Correctly modeling redshift distortion is thus essential, and the new prescription for the redshift-space power spectrum including the nonlinear corrections can be used as an accurate theoretical template for anisotropic BAOs.

  16. Cascaded gain fibers for increasing output power and the stimulated Brillouin scattering threshold of narrow linewidth fiber Raman amplifiers.

    PubMed

    Nagel, J A; Temyanko, V; Dobler, J T; Likhachev, M E; Bubnov, M M; Dianov, E M; Peyghambarian, N

    2016-05-20

    We show both experimentally and theoretically a method to increase the stimulated Brillouin scattering (SBS) threshold and output power of narrow linewidth fiber Raman amplifiers. This method employs two or more fibers with varying concentrations of the Raman gain material dopant such as GeO2 or P2O5 in silicate-based glasses. These fibers are then cascaded to form an amplifier gain stage, disrupting the buildup of SBS that normally occurs in single continuous fibers. The numerical model shown is applicable to arbitrary amplifier systems for gain stage optimization and increased power scaling. We give experimental results for phosphosilicate fibers that agree well with simulation predictions that support the numerical model used. PMID:27411133

  17. Numerical simulations of output pulse extraction from a high-power microwave compressor with a plasma switch

    SciTech Connect

    Shlapakovski, Anatoli; Beilin, Leonid; Bliokh, Yuri; Donskoy, Moshe; Krasik, Yakov E.; Hadas, Yoav; Schamiloglu, Edl

    2014-05-07

    Numerical simulations of the process of electromagnetic energy release from a high-power microwave pulse compressor comprising a gas-filled cavity and interference switch were carried out. A microwave plasma discharge in a rectangular waveguide H-plane tee was modeled with the use of the fully electromagnetic particle-in-cell code MAGIC. The gas ionization, plasma evolution, and interaction with RF fields accumulated within the compressor were simulated using different approaches provided by the MAGIC code: particle-in-cell approach accounting for electron-neutral collisions, gas conductivity model based on the concept of mobility, and hybrid modeling. The dependences of the microwave output pulse peak power and waveform on parameters that can be controlled in experiments, such as an external ionization rate, RF field amplitude, and background gas pressure, were investigated.

  18. The influence of non-logarithmic wind speed profiles on potential power output at Danish offshore sites

    NASA Astrophysics Data System (ADS)

    Motta, M.; Barthelmie, R. J.; Vølund, P.

    2005-04-01

    Detailed knowledge of mean wind speed profiles is essential for properly assessing the power output of a potential wind farm. Since atmospheric stratification plays a crucial role in affecting wind speed profiles, obtaining a detailed picture of the climatology of stability conditions at a given site is very important. In the present study, long time series from offshore measurement sites around Denmark are analysed, with the aim of quantifying the role of atmospheric stability in wind speed profiles and in our ability to model them. A simple method for evaluating stability is applied, and the resulting statistics of the atmospheric stratification is thoroughly studied. A significant improvement in the mean wind speed profile prediction is obtained by applying a stability correction to the logarithmic profiles suitable for neutral conditions. These results are finally used to estimate power densities at different heights. Copyright

  19. Measurement of Trailing Edge Noise Using Directional Array and Coherent Output Power Methods

    NASA Technical Reports Server (NTRS)

    Hutcheson, Florence V.; Brooks, Thomas F.

    2002-01-01

    The use of a directional (or phased) array of microphones for the measurement of trailing edge (TE) noise is described and tested. The capabilities of this method arc evaluated via measurements of TE noise from a NACA 63-215 airfoil model and from a cylindrical rod. This TE noise measurement approach is compared to one that is based on thc cross spectral analysis of output signals from a pair of microphones placed on opposite sides of an airframe model (COP method). Advantages and limitations of both methods arc examined. It is shown that the microphone array can accurately measures TE noise and captures its two-dimensional characteristic over a large frequency range for any TE configuration as long as noise contamination from extraneous sources is within bounds. The COP method is shown to also accurately measure TE noise but over a more limited frequency range that narrows for increased TE thickness. Finally, the applicability and generality of an airfoil self-noise prediction method was evaluated via comparison to the experimental data obtained using the COP and array measurement methods. The predicted and experimental results are shown to agree over large frequency ranges.

  20. Measurement Of Trailing Edge Noise using Directional Array and Coherent Output Power Methods

    NASA Technical Reports Server (NTRS)

    Hutcheson, Florence V.; Brooks, Thomas F.

    2002-01-01

    The use of a directional array of microphones for the measurement of trailing edge (TE) noise is described. The capabilities of this method are evaluated via measurements of TE noise from a NACA 63-215 airfoil model and from a cylindrical rod. This TE noise measurement approach is compared to one that is based on the cross spectral analysis of output signals from a pair of microphones (COP method). Advantages and limitations of both methods are examined. It is shown that the microphone array can accurately measures TE noise and captures its two-dimensional characteristic over a large frequency range for any TE configuration as long as noise contamination from extraneous sources is within bounds. The COP method is shown to also accurately measure TE noise but over a more limited frequency range that narrows for increased TE thickness. Finally, the applicability and generality of an airfoil self-noise prediction method was evaluated via comparison to the experimental data obtained using the COP and array measurement methods. The predicted and experimental results are shown to agree over large frequency ranges.

  1. Benthic microbial fuel cell as direct power source for an acoustic modem and seawater oxygen/temperature sensor system.

    PubMed

    Gong, Yanming; Radachowsky, Sage E; Wolf, Michael; Nielsen, Mark E; Girguis, Peter R; Reimers, Clare E

    2011-06-01

    Supported by the natural potential difference between anoxic sediment and oxic seawater, benthic microbial fuel cells (BMFCs) promise to be ideal power sources for certain low-power marine sensors and communication devices. In this study a chambered BMFC with a 0.25 m(2) footprint was used to power an acoustic modem interfaced with an oceanographic sensor that measures dissolved oxygen and temperature. The experiment was conducted in Yaquina Bay, Oregon over 50 days. Several improvements were made in the BMFC design and power management system based on lessons learned from earlier prototypes. The energy was harvested by a dynamic gain charge pump circuit that maintains a desired point on the BMFC's power curve and stores the energy in a 200 F supercapacitor. The system also used an ultralow power microcontroller and quartz clock to read the oxygen/temperature sensor hourly, store data with a time stamp, and perform daily polarizations. Data records were transmitted to the surface by the acoustic modem every 1-5 days after receiving an acoustic prompt from a surface hydrophone. After jump-starting energy production with supplemental macroalgae placed in the BMFC's anode chamber, the average power density of the BMFC adjusted to 44 mW/m(2) of seafloor area which is better than past demonstrations at this site. The highest power density was 158 mW/m(2), and the useful energy produced and stored was ≥ 1.7 times the energy required to operate the system. PMID:21545151

  2. Torque and power outputs on different subjects during manual wheelchair propulsion under different conditions

    NASA Astrophysics Data System (ADS)

    Hwang, Seonhong; Kim, Seunghyeon; Son, Jongsang; Kim, Youngho

    2012-02-01

    Manual wheelchair users are at a high risk of pain and injuries to the upper extremities due to mechanical inefficiency of wheelchair propulsion motion. The kinetic analysis of the upper extremities during manual wheelchair propulsion in various conditions needed to be investigated. We developed and calibrated a wheelchair dynamometer for measuring kinetic parameters during propulsion. We utilized the dynamometer to investigate and compare the propulsion torque and power values of experienced and novice users under four different conditions. Experienced wheelchair users generated lower torques with more power than novice users and reacted alertly and sensitively to changing conditions. We expect that these basic methods and results may help to quantitatively evaluate the mechanical efficiency of manual wheelchair propulsion.

  3. Yaw-Misalignment and its Impact on Wind Turbine Loads and Wind Farm Power Output

    NASA Astrophysics Data System (ADS)

    van Dijk, Mike T.; van Wingerden, Jan-Willem; Ashuri, Turaj; Li, Yaoyu; Rotea, Mario A.

    2016-09-01

    To make wind energy cost competitive with traditional resources, wind turbines are commonly placed in groups. Aerodynamic interaction between the turbines causes sub-optimal energy production. A control strategy to mitigate these losses is by redirecting the wake by yaw misalignment. This paper aims to assess the influence of load variations of the rotor due to partial wake overlap and presents a combined optimization of the power and loads using wake redirection. For this purpose, we design a computational framework which computes the wind farm power production and the wind turbine rotor loads based on the yaw settings. The simulation results show that partial wake overlap can significantly increase asymmetric loading of the rotor disk and that yaw misalignment is beneficial in situations where the wake can be sufficiently directed away from the downstream turbine.

  4. Inverted tetrahedron-pyramidal micropatterned polymer films for boosting light output power in flip-chip light-emitting diodes.

    PubMed

    Leem, Jung Woo; Lee, Soo Hyun; Guan, Xiang-Yu; Yu, Jae Su

    2015-04-20

    We report the improved light output power in gallium nitride-based green flip-chip light-emitting diodes (FCLEDs) employed with inverted tetrahedron-pyramidal micropatterned polydimethylsiloxane (ITPM PDMS) films as an encapsulation and protection layer. The micropatterns are transferred into the surface of PDMS films from the sapphire substrate master molds with two-dimensional periodic hexagonal TPM arrays by a soft imprint lithography method. The ITPM PDMS film laminated on the sapphire dramatically enhances the diffuse transmittance (T(D)) in a wavelength (λ) range of 400-650 nm, exhibiting the larger T(D) value of ~53% at λ = 525 nm, (cf., T(D) ~1% for planar sapphire). By introducing the ITPM PDMS film on the outer surface of sapphire in FCLEDs, the light output power is enhanced, indicating the increment percentage of ~11.1% at 500 mA of injection current compared to the reference FCLED without the ITPM PDMS film, together with better electroluminescence intensity and far-field radiation pattern. PMID:25968997

  5. Inverted tetrahedron-pyramidal micropatterned polymer films for boosting light output power in flip-chip light-emitting diodes.

    PubMed

    Leem, Jung Woo; Lee, Soo Hyun; Guan, Xiang-Yu; Yu, Jae Su

    2015-04-20

    We report the improved light output power in gallium nitride-based green flip-chip light-emitting diodes (FCLEDs) employed with inverted tetrahedron-pyramidal micropatterned polydimethylsiloxane (ITPM PDMS) films as an encapsulation and protection layer. The micropatterns are transferred into the surface of PDMS films from the sapphire substrate master molds with two-dimensional periodic hexagonal TPM arrays by a soft imprint lithography method. The ITPM PDMS film laminated on the sapphire dramatically enhances the diffuse transmittance (T(D)) in a wavelength (λ) range of 400-650 nm, exhibiting the larger T(D) value of ~53% at λ = 525 nm, (cf., T(D) ~1% for planar sapphire). By introducing the ITPM PDMS film on the outer surface of sapphire in FCLEDs, the light output power is enhanced, indicating the increment percentage of ~11.1% at 500 mA of injection current compared to the reference FCLED without the ITPM PDMS film, together with better electroluminescence intensity and far-field radiation pattern.

  6. Influence of different stimulation frequencies on power output and fatigue during FES-cycling in recently injured SCI people.

    PubMed

    Eser, Prisca C; Donaldson, Nick de N; Knecht, Hans; Stüssi, Edgar

    2003-09-01

    This study investigated whether power output during 30 min sessions of functional electrical stimulation (FES)-cycling can be increased by using stimulation frequencies higher than 30 Hz. The stimulation frequencies of FES-cycling training sessions of 19 recently injured para- and tetraplegics were randomly set at 30, 50, or 60 Hz and power output (PO) was measured continually. The mean PO of the 30 min, the PO of the last minute of each session, and the minimum PO were significantly greater at 60 and 50 Hz than at 30 Hz (ANOVA without cross-product). A 19% and 25% higher mean PO was reached at 50 and 60 Hz, respectively, compared to 30 Hz. The PO of the last minute of each session was almost always higher than the mean PO of the whole session and also higher at higher frequencies, which indicates that no muscle fatigue could be detected in 30 min FES-cycling at any of the tested frequencies.

  7. High-output-power, single-wavelength silicon hybrid laser using precise flip-chip bonding technology.

    PubMed

    Tanaka, Shinsuke; Jeong, Seok-Hwan; Sekiguchi, Shigeaki; Kurahashi, Teruo; Tanaka, Yu; Morito, Ken

    2012-12-17

    An Si/III-V hybrid laser oscillating at a single wavelength was developed for use in a large-scale Si optical I/O chip. The laser had an InP-based reflective semiconductor optical amplifier (SOA) chip integrated with an Si wavelength-selection-mirror chip in a flip-chip configuration. A low coupling loss of 1.55 dB at the Si-SOA interface was accomplished by both mode-field-matching between Si-SOA waveguides and accurately controlling the bonding position. The fabricated Si hybrid laser exhibited a very low threshold current of 9.4 mA, a high output power of 15.0 mW, and a high wall-plug efficiency of 7.6% at 20 °C. Moreover, the device maintained a high output power of >10 mW up to 60°C due to the high thermal conductance between the SOA chip and Si substrate. The short cavity length of the flip-chip bonded laser expanded the longitudinal mode spacing. This resulted in temperature-stable single longitudinal mode lasing and a low RIN level of <-130 dB/Hz.

  8. A dark jet dominates the power output of the stellar black hole Cygnus X-1.

    PubMed

    Gallo, Elena; Fender, Rob; Kaiser, Christian; Russell, David; Morganti, Raffaella; Oosterloo, Tom; Heinz, Sebastian

    2005-08-11

    Black holes undergoing accretion are thought to emit the bulk of their power in the X-ray band by releasing the gravitational potential energy of the infalling matter. At the same time, they are capable of producing highly collimated jets of energy and particles flowing out of the system with relativistic velocities. Here we show that the 10-solar-mass (10M(o)) black hole in the X-ray binary Cygnus X-1 (refs 3-5) is surrounded by a large-scale (approximately 5 pc in diameter) ring-like structure that appears to be inflated by the inner radio jet. We estimate that in order to sustain the observed emission of the ring, the jet of Cygnus X-1 has to carry a kinetic power that can be as high as the bolometric X-ray luminosity of the binary system. This result may imply that low-luminosity stellar-mass black holes as a whole dissipate the bulk of the liberated accretion power in the form of 'dark', radiatively inefficient relativistic outflows, rather than locally in the X-ray-emitting inflow.

  9. Muscle power output properties using the stretch-shortening cycle of the upper limb and their relationships with a one-repetition maximum bench press.

    PubMed

    Miyaguchi, Kazuyoshi; Demura, Shinichi

    2006-05-01

    The purpose of this study was to examine the output properties of muscle power by the dominant upper limb using SSC, and the relationships between the power output by SSC and a one-repetition maximum bench press (1 RM BP) used as a strength indicator of the upper body. Sixteen male athletes (21.4+/-0.9 yr) participated in this study. They pulled a load of 40% of maximum voluntary contraction (MVC) at a stretch by elbow flexion of the dominant upper limb in the following three preliminary conditions: static relaxed muscle state (SR condition), isometric muscle contraction state (ISO condition), and using SSC (SSC condition). The velocity with a wire load via a pulley during elbow flexion was measured accurately using a power instrument with a rotary encoder, and the muscle power curve was drawn from the product of the velocity and load. Significant differences were found among all evaluation parameters of muscle power exerted from the above three conditions and the parameters regarding early power output during concentric contraction were larger in the SSC condition than the SR and ISO conditions. The parameters on initial muscle contraction velocity when only using SSC significantly correlated with 1 RM BP (r=0.60-0.62). The use of SSC before powerful elbow flexion may contribute largely to early explosive power output during concentric contraction. Bench press capacity relates to a development of the above early power output when using SSC. PMID:16763366

  10. Low power underwater acoustic DPSK detection: Theoretical prediction and experimental results

    NASA Astrophysics Data System (ADS)

    Dunne, Andrew

    This thesis presents two methods of analyzing the effectiveness of a prototype differential phase-shift keying (DPSK) detection circuit. The first method is to make modifications to the existing hardware to reliably output and record the cross-correlation values of the DPSK detection process. The second method is to write a MATLAB detection algorithm which accurately simulates the detection results of the hardware system without the need of any electronics. These two systems were tested and verified with a bench test using computer generated DPSK signals. The hardware system was tested using real acoustic data from shallow and deep water at-sea tests to determine the effectiveness of the DPSK detection circuit in different ocean environments. The hydrophone signals from the tests were recorded so that the cross-correlation values could be verified using the MATLAB detector. As a result of this study, these two systems provided more insight into how well the DPSK detection prototype works and helped to identify ways of improving the detection reliability and overall performance of the prototype DPSK detection circuit.

  11. Structural Dynamic Assessment of the GN2 Piping System for NASA's New and Powerful Reverberant Acoustic Test Facility

    NASA Technical Reports Server (NTRS)

    McNelis, Mark E.; Staab, Lucas D.; Akers, James C.; Hughes, William O.; Chang, Li C.; Hozman, Aron D.; Henry, Michael W.

    2012-01-01

    The National Aeronautics and Space Administration (NASA) Glenn Research Center (GRC) has led the design and build of the new world-class vibroacoustic test capabilities at the NASA GRC's Plum Brook Station in Sandusky, Ohio, USA from 2007 to 2011. SAIC-Benham has completed construction of a new reverberant acoustic test facility to support the future testing needs of NASA's space exploration program and commercial customers. The large Reverberant Acoustic Test Facility (RATF) is approximately 101,000 cubic feet in volume and was designed to operate at a maximum empty chamber acoustic overall sound pressure level (OASPL) of 163 dB. This combination of size and acoustic power is unprecedented amongst the world s known active reverberant acoustic test facilities. Initial checkout acoustic testing was performed on March 2011 by SAIC-Benham at test levels up to 161 dB OASPL. During testing, several branches of the gaseous nitrogen (GN2) piping system, which supply the fluid to the noise generating acoustic modulators, failed at their T-junctions connecting the 12 in. supply line to their respective 4 in. branch lines. The problem was initially detected when the oxygen sensors in the horn room indicated a lower than expected oxygen level from which was inferred GN2 leaks in the piping system. In subsequent follow up inspections, cracks were identified in the failed T-junction connections through non-destructive evaluation testing. Through structural dynamic modeling of the piping system, the root cause of the T-junction connection failures was determined. The structural dynamic assessment identified several possible corrective design improvements to the horn room piping system. The effectiveness of the chosen design repairs were subsequently evaluated in September 2011 during acoustic verification testing to 161 dB OASPL.

  12. Structural Dynamic Assessment of the GN2 Piping System for NASA's New and Powerful Reverberant Acoustic Test Facility

    NASA Technical Reports Server (NTRS)

    McNelis, Mark E.; Staab, Lucas D.; Akers, James C.; Hughes, WIlliam O.; Chang, Li, C.; Hozman, Aron D.; Henry, Michael W.

    2012-01-01

    The National Aeronautics and Space Administration (NASA) Glenn Research Center (GRC) has led the design and build of the new world-class vibroacoustic test capabilities at the NASA GRC's Plum Brook Station in Sandusky, Ohio, USA from 2007-2011. SAIC-Benham has completed construction of a new reverberant acoustic test facility to support the future testing needs of NASA's space exploration program and commercial customers. The large Reverberant Acoustic Test Facility (RATF) is approximately 101,000 cu ft in volume and was designed to operate at a maximum empty chamber acoustic overall sound pressure level (OASPL) of 163 dB. This combination of size and acoustic power is unprecedented amongst the world's known active reverberant acoustic test facilities. Initial checkout acoustic testing was performed on March 2011 by SAIC-Benham at test levels up to 161 dB OASPL. During testing, several branches of the gaseous nitrogen (GN2) piping system, which supply the fluid to the noise generating acoustic modulators, failed at their "t-junctions" connecting the 12 inch supply line to their respective 4 inch branch lines. The problem was initially detected when the oxygen sensors in the horn room indicated a lower than expected oxygen level from which was inferred GN2 leaks in the piping system. In subsequent follow up inspections, cracks were identified in the failed "t-junction" connections through non-destructive evaluation testing . Through structural dynamic modeling of the piping system, the root cause of the "t-junction" connection failures was determined. The structural dynamic assessment identified several possible corrective design improvements to the horn room piping system. The effectiveness of the chosen design repairs were subsequently evaluated in September 2011 during acoustic verification testing to 161 dB OASPL.

  13. Evaluation of piezoelectric material properties for a higher power output from energy harvesters with insight into material selection using a coupled piezoelectric-circuit-finite element method.

    PubMed

    Daniels, Alice; Zhu, Meiling; Tiwari, Ashutosh

    2013-12-01

    Piezoelectric material properties have substantial influence on electrical power output from piezoelectric energy harvesters (PEHs). Understanding their influences is the first step in designing effective PEHs to generate higher power outputs. This paper uses a coupled piezoelectric-circuit-finite element method to study the power outputs of different types of piezoelectric materials, including single crystal, polyvinylidene fluoride (PVDF), and soft and hard lead zirconate titanate (PZT) materials. The purpose of this study is to try to gain an understanding of which piezoelectric material property--the elastic compliance s11, the piezoelectric strain constant d31, the piezoelectric stress constant g31, and the relative dielectric constant ϵ(T)r33, and the associated material properties of the d31 × g31, called the figure of merit (FOM), and the coupling coefficient k31--dominates the power output. A rectangular piezoelectric plate under a low-frequency excitation is used to evaluate piezoelectric material properties for a higher power output. It was found that 1) d31 is a more dominant material property over other material properties for higher power output; 2) FOM was more linearly related to the power output than either the k31 or the d31; and 3) ϵ(T)r33 had some role; when the materials have an identical d31; a lower ϵ(T)r33 was preferred. Because of unexplained outliers, no single material parameter was able to be recommended as selection criteria, but combined FOM with d31 parameters is recommended for selection of piezoelectric material for a higher power output from PEHs.

  14. Can we estimate the cellular phone RF peak output power with a simple experiment?

    NASA Astrophysics Data System (ADS)

    Fioreze, Maycon; dos Santos Junior, Sauli; Goncalves Hönnicke, Marcelo

    2016-07-01

    Cellular phones are becoming increasingly useful tools for students. Since cell phones operate in the microwave bandwidth, they can be used to motivate students to demonstrate and better understand the properties of electromagnetic waves. However, since these waves operate at higher frequencies (L-band, from 800 MHz to 2 GHz) it is not simple to detect them. Usually, expensive real-time high frequency oscilloscopes are required. Indirect measurements are also possible through heat-based and diode-detector-based radio-frequency (RF) power sensors. Another didactic and intuitive way is to explore a simple and inexpensive detection system, based on the interference effect caused in the electronic circuit of TV and PC soundspeakers, and to try to investigate different properties of the cell phones’ RF electromagnetic waves, such as its power and modulated frequency. This manuscript proposes a trial to quantify these measurements, based on a simple Friis equation model and the time constant of the circuit used in the detection system, in order to show it didactically to the students and even allow them also to explore such a simple detection system at home.

  15. Integrating engineering design improvements with exoelectrogen enrichmentprocess to increase power output from microbial fuel cells

    SciTech Connect

    Borole, Abhijeet P; Hamilton, Choo Yieng; Vishnivetskaya, Tatiana A; Leak, David; Andras, Calin; Morrell-Falvey, Jennifer L; Keller, Martin; Davison, Brian H

    2009-01-01

    Microbial fuel cells (MFC) hold promise as a green technology for bioenergy production. The challenge is to improve the engineering design while exploiting the ability of microbes to generate and transfer electrons directly to electrodes. A strategy using a combination of improved anode design and an enrichment processwas formulated to improve power densities. The designwas based on a flow-through anode with minimal dead volume and a high electrode surface area per unit volume. The strategy focused on promoting biofilm formation via a combination of forced flow through the anode, carbon limitation, and step-wise reduction of external resistance. The enrichment process resulted in development of exoelectrogenic biofilm communities dominated by Anaeromusa spp. This is the first report identifying organisms fromthe Veillonellaceae family in MFCs. The power density of the resulting MFC using a ferricyanide cathode reached 300Wm−3 net anode volume (3220mWm−2), which is about a third of what is estimated to be necessary for commercial consideration. The operational stability of the MFC using high specific surface area electrodes was demonstrated by operating the MFC for a period of over four months.

  16. Doubling Power Output of Starch Biobattery Treated by the Most Thermostable Isoamylase from an Archaeon Sulfolobus tokodaii

    PubMed Central

    Cheng, Kun; Zhang, Fei; Sun, Fangfang; Chen, Hongge; Percival Zhang, Y-H

    2015-01-01

    Biobattery, a kind of enzymatic fuel cells, can convert organic compounds (e.g., glucose, starch) to electricity in a closed system without moving parts. Inspired by natural starch metabolism catalyzed by starch phosphorylase, isoamylase is essential to debranch alpha-1,6-glycosidic bonds of starch, yielding linear amylodextrin – the best fuel for sugar-powered biobattery. However, there is no thermostable isoamylase stable enough for simultaneous starch gelatinization and enzymatic hydrolysis, different from the case of thermostable alpha-amylase. A putative isoamylase gene was mined from megagenomic database. The open reading frame ST0928 from a hyperthermophilic archaeron Sulfolobus tokodaii was cloned and expressed in E. coli. The recombinant protein was easily purified by heat precipitation at 80 oC for 30 min. This enzyme was characterized and required Mg2+ as an activator. This enzyme was the most stable isoamylase reported with a half lifetime of 200 min at 90 oC in the presence of 0.5 mM MgCl2, suitable for simultaneous starch gelatinization and isoamylase hydrolysis. The cuvett-based air-breathing biobattery powered by isoamylase-treated starch exhibited nearly doubled power outputs than that powered by the same concentration starch solution, suggesting more glucose 1-phosphate generated. PMID:26289411

  17. Doubling Power Output of Starch Biobattery Treated by the Most Thermostable Isoamylase from an Archaeon Sulfolobus tokodaii.

    PubMed

    Cheng, Kun; Zhang, Fei; Sun, Fangfang; Chen, Hongge; Percival Zhang, Y-H

    2015-08-20

    Biobattery, a kind of enzymatic fuel cells, can convert organic compounds (e.g., glucose, starch) to electricity in a closed system without moving parts. Inspired by natural starch metabolism catalyzed by starch phosphorylase, isoamylase is essential to debranch alpha-1,6-glycosidic bonds of starch, yielding linear amylodextrin - the best fuel for sugar-powered biobattery. However, there is no thermostable isoamylase stable enough for simultaneous starch gelatinization and enzymatic hydrolysis, different from the case of thermostable alpha-amylase. A putative isoamylase gene was mined from megagenomic database. The open reading frame ST0928 from a hyperthermophilic archaeron Sulfolobus tokodaii was cloned and expressed in E. coli. The recombinant protein was easily purified by heat precipitation at 80 (o)C for 30 min. This enzyme was characterized and required Mg(2+) as an activator. This enzyme was the most stable isoamylase reported with a half lifetime of 200 min at 90 (o)C in the presence of 0.5 mM MgCl2, suitable for simultaneous starch gelatinization and isoamylase hydrolysis. The cuvett-based air-breathing biobattery powered by isoamylase-treated starch exhibited nearly doubled power outputs than that powered by the same concentration starch solution, suggesting more glucose 1-phosphate generated.

  18. Graphite anode surface modification with controlled reduction of specific aryl diazonium salts for improved microbial fuel cells power output.

    PubMed

    Picot, Matthieu; Lapinsonnière, Laure; Rothballer, Michael; Barrière, Frédéric

    2011-10-15

    Graphite electrodes were modified with reduction of aryl diazonium salts and implemented as anodes in microbial fuel cells. First, reduction of 4-aminophenyl diazonium is considered using increased coulombic charge density from 16.5 to 200 mC/cm(2). This procedure introduced aryl amine functionalities at the surface which are neutral at neutral pH. These electrodes were implemented as anodes in "H" type microbial fuel cells inoculated with waste water, acetate as the substrate and using ferricyanide reduction at the cathode and a 1000 Ω external resistance. When the microbial anode had developed, the performances of the microbial fuel cells were measured under acetate saturation conditions and compared with those of control microbial fuel cells having an unmodified graphite anode. We found that the maximum power density of microbial fuel cell first increased as a function of the extent of modification, reaching an optimum after which it decreased for higher degree of surface modification, becoming even less performing than the control microbial fuel cell. Then, the effect of the introduction of charged groups at the surface was investigated at a low degree of surface modification. It was found that negatively charged groups at the surface (carboxylate) decreased microbial fuel cell power output while the introduction of positively charged groups doubled the power output. Scanning electron microscopy revealed that the microbial anode modified with positively charged groups was covered by a dense and homogeneous biofilm. Fluorescence in situ hybridization analyses showed that this biofilm consisted to a large extent of bacteria from the known electroactive Geobacter genus. In summary, the extent of modification of the anode was found to be critical for the microbial fuel cell performance. The nature of the chemical group introduced at the electrode surface was also found to significantly affect the performance of the microbial fuel cells. The method used for

  19. Lithium-Ion Ultracapacitors integrated with Wind Turbines Power Conversion Systems to Extend Operating Life and Improve Output Power Quality

    SciTech Connect

    Nasiri, Adel

    2012-05-23

    In this project we designed and modeled a system for a full conversion wind turbine and built a scaled down model which utilizes Lithium-Ion Capacitors on the DC bus. One of the objectives is to reduce the mechanical stress on the gearbox and drivetrain of the wind turbine by adjusting the torque on generator side according to incoming wind power. Another objective is to provide short-term support for wind energy to be more grid friendly in order to ultimately increase wind energy penetration. These supports include power smoothing, power ramp rate limitation, low voltage ride through, and frequency (inertia) support. This research shows how energy storage in small scale and in an economical fashion can make a significant impact on performance of wind turbines. Gearbox and drivetrain premature failures are among high cost maintenance items for wind turbines. Since the capacitors are directly applied on the turbine DC bus and their integration does not require addition hardware, the cost of the additional system can be reasonable for the wind turbine manufacturers and utility companies.

  20. Continuous wave diode pumped intracavity doubled Nd:GdVO 4 laser with 840 mW output power at 456 nm

    NASA Astrophysics Data System (ADS)

    Czeranowsky, C.; Schmidt, M.; Heumann, E.; Huber, G.; Kutovoi, S.; Zavartsev, Y.

    2002-05-01

    We present a diode pumped Nd:GdVO 4 ground-state laser at 912 nm with a maximum cw output power of nearly 2.1 W at 16.7 W pump power. The slope efficiency was 16% with respect to the incident power. Also intracavity second harmonic generation (SHG) with an LBO crystal into the blue spectral range at 456 nm was achieved with a maximum output power of 840 mW. In addition the spectral data of Nd:GdVO 4 are presented and compared with those of Nd:YVO 4 and Nd:YAG.

  1. Physics of Output Power Limitations in Long-Wavelength Laser Diodes

    NASA Astrophysics Data System (ADS)

    Piprek, Joachim; White, J. Kenton; SpringThorpe, Anthony J.

    2002-12-01

    We analyze the high-temperature continuous-wave performance of 1.3 micron AlGaInAs/InP laser diodes grown by digital alloy molecular beam epitaxy. Commercial laser software is utilized that self-consistently combines quantum well bandstructure and gain calculations with two-dimensional simulations of carrier transport, wave guiding, and heat flow. Excellent agreement between simulation and measurements is obtained by careful adjustment of material parameters in the model. Joule heating is shown to be the main heat source; quantum well recombination heat is almost compensated for by Thomson cooling. Auger recombination is the main carrier loss mechanism at lower injection current. Vertical electron escape into the p-doped InP cladding dominates at higher current and it causes the thermal power roll-off. Self-heating and optical gain reduction are the triggering mechanisms behind the leakage escalation.

  2. Uncalibrated pulse power analysis fails to reliably measure cardiac output in patients undergoing coronary artery bypass surgery

    PubMed Central

    2011-01-01

    Introduction Uncalibrated arterial pulse power analysis has been recently introduced for continuous monitoring of cardiac index (CI). The aim of the present study was to compare the accuracy of arterial pulse power analysis with intermittent transpulmonary thermodilution (TPTD) before and after cardiopulmonary bypass (CPB). Methods Forty-two patients scheduled for elective coronary surgery were studied after induction of anaesthesia, before and after CPB respectively. Each patient was monitored with the pulse contour cardiac output (PiCCO) system, a central venous line and the recently introduced LiDCO monitoring system. Haemodynamic variables included measurement of CI derived by transpulmonary thermodilution (CITPTD) or CI derived by pulse power analysis (CIPP), before and after calibration (CIPPnon-cal., CIPPcal.). Percentage changes of CI (ΔCITPTD, ΔCIPPnon-cal./PPcal.) were calculated to analyse directional changes. Results Before CPB there was no significant correlation between CIPPnon-cal. and CITPTD (r2 = 0.04, P = 0.08) with a percentage error (PE) of 86%. Higher mean arterial pressure (MAP) values were significantly correlated with higher CIPPnon-cal. (r2 = 0.26, P < 0.0001). After CPB, CIPPcal. revealed a significant correlation compared with CITPTD (r2 = 0.77, P < 0.0001) with PE of 28%. Changes in CIPPcal. (ΔCIPPcal.) showed a correlation with changes in CITPTD (ΔCITPTD) only after CPB (r2 = 0.52, P = 0.005). Conclusions Uncalibrated pulse power analysis was significantly influenced by MAP and was not able to reliably measure CI compared with TPTD. Calibration improved accuracy, but pulse power analysis was still not consistently interchangeable with TPTD. Only calibrated pulse power analysis was able to reliably track haemodynamic changes and trends. PMID:21356060

  3. Solar cycle variations in the powers and damping rates of low-degree solar acoustic oscillations

    NASA Astrophysics Data System (ADS)

    Broomhall, A.-M.; Pugh, C. E.; Nakariakov, V. M.

    2015-12-01

    Helioseismology uses the Sun's natural resonant oscillations to study the solar interior. The properties of the solar oscillations are sensitive to the Sun'2019;s magnetic activity cycle. Here we examine variations in the powers, damping rates, and energy supply rates of the most prominent acoustic oscillations in unresolved, Sun-as-a-star data, obtained by the Birmingham Solar Oscillations Network (BiSON) during solar cycles 22, 23, and the first half of 24. The variations in the helioseismic parameters are compared to the 10.7 cm flux, a well-known global proxy of solar activity. As expected the oscillations are most heavily damped and the mode powers are at a minimum at solar activity maximum. The 10.7 cm flux was linearly regressed using the fractional variations of damping rates and powers observed during cycle 23. In general, good agreement is found between the damping rates and the 10.7 cm flux. However, the linearly regressed 10.7 cm flux and fractional variation in powers diverge in cycles 22 and 24, indicating that the relationship between the mode powers and the 10.7 cm flux is not consistent from one cycle to the next. The energy supply rate of the oscillations, which is usually approximately constant, also decreases at this time. We have determined that this discrepancy is not because of the first-order bias introduced by an increase in the level of background noise or gaps in the data. Although we cannot categorically rule out an instrumental origin, the divergence observed in cycle 24, when the data were of high quality and the data coverage was over 80%, raises the possibility that the effect may be solar in origin.

  4. Effects of age and recovery duration on peak power output during repeated cycling sprints.

    PubMed

    Ratel, S; Bedu, M; Hennegrave, A; Doré, E; Duché, P

    2002-08-01

    The aim of the present study was to investigate the effects of age and recovery duration on the time course of cycling peak power and blood lactate concentration ([La]) during repeated bouts of short-term high-intensity exercise. Eleven prepubescent boys (9.6 +/- 0.7 yr), nine pubescent boys (15.0 +/- 0.7 yr) and ten men (20.4 +/- 0.8 yr) performed ten consecutive 10 s cycling sprints separated by either 30 s (R30), 1 min (R1), or 5 min (R5) passive recovery intervals against a friction load corresponding to 50 % of their optimal force (50 % Ffopt). Peak power produced at 50 % Ffopt (PP50) was calculated at each sprint including the flywheel inertia of the bicycle. Arterialized capillary blood samples were collected at rest and during the sprint exercises to measure the time course of [La]. In the prepubescent boys, whatever recovery intervals, PP50 remained unchanged during the ten 10 s sprint exercises. In the pubescent boys, PP50 decreased significantly by 18.5 % (p < 0.001) with R30 and by 15.3 % (p < 0.01) with R1 from the first to the tenth sprint but remained unchanged with R5. In the men, PP50 decreased respectively by 28.5 % (p < 0.001) and 11.3 % (p < 0.01) with R30 and R1 and slightly diminished with R5. For each recovery interval, the increase in blood [La] over the ten sprints was significantly lower in the prepubescent boys compared with the pubescent boys and the men. To conclude, the prepubescent boys sustained their PP50 during the ten 10 s sprint exercises with only 30 s recovery intervals. In contrast, the pubescent boys and the men needed 5 min recovery intervals. It was suggested that the faster recovery of PP50 in the prepubescent boys was due to their lower muscle glycolytic activity and their higher muscle oxidative capacity allowing a faster resynthesis in phosphocreatine. PMID:12215957

  5. Effects of age and recovery duration on peak power output during repeated cycling sprints.

    PubMed

    Ratel, S; Bedu, M; Hennegrave, A; Doré, E; Duché, P

    2002-08-01

    The aim of the present study was to investigate the effects of age and recovery duration on the time course of cycling peak power and blood lactate concentration ([La]) during repeated bouts of short-term high-intensity exercise. Eleven prepubescent boys (9.6 +/- 0.7 yr), nine pubescent boys (15.0 +/- 0.7 yr) and ten men (20.4 +/- 0.8 yr) performed ten consecutive 10 s cycling sprints separated by either 30 s (R30), 1 min (R1), or 5 min (R5) passive recovery intervals against a friction load corresponding to 50 % of their optimal force (50 % Ffopt). Peak power produced at 50 % Ffopt (PP50) was calculated at each sprint including the flywheel inertia of the bicycle. Arterialized capillary blood samples were collected at rest and during the sprint exercises to measure the time course of [La]. In the prepubescent boys, whatever recovery intervals, PP50 remained unchanged during the ten 10 s sprint exercises. In the pubescent boys, PP50 decreased significantly by 18.5 % (p < 0.001) with R30 and by 15.3 % (p < 0.01) with R1 from the first to the tenth sprint but remained unchanged with R5. In the men, PP50 decreased respectively by 28.5 % (p < 0.001) and 11.3 % (p < 0.01) with R30 and R1 and slightly diminished with R5. For each recovery interval, the increase in blood [La] over the ten sprints was significantly lower in the prepubescent boys compared with the pubescent boys and the men. To conclude, the prepubescent boys sustained their PP50 during the ten 10 s sprint exercises with only 30 s recovery intervals. In contrast, the pubescent boys and the men needed 5 min recovery intervals. It was suggested that the faster recovery of PP50 in the prepubescent boys was due to their lower muscle glycolytic activity and their higher muscle oxidative capacity allowing a faster resynthesis in phosphocreatine.

  6. Double-pass tapered amplifier diode laser with an output power of 1 W for an injection power of only 200 μW.

    PubMed

    Bolpasi, V; von Klitzing, W

    2010-11-01

    A 1 W tapered amplifier requiring only 200 μW of injection power at 780 nm is presented in this paper. This is achieved by injecting the seeding light into the amplifier from its tapered side and feeding the amplified light back into the small side. The amplified spontaneous emission of the tapered amplifier is suppressed by 75 dB. The double-passed tapered laser, presented here, is extremely stable and reliable. The output beam remains well coupled to the optical fiber for a timescale of months, whereas the injection of the seed light did not require realignment for over a year of daily operation. PMID:21133462

  7. Vibration shape effects on the power output in piezoelectric vibro-impact energy harvesters

    NASA Astrophysics Data System (ADS)

    Twiefel, Jens

    2013-04-01

    strain distribution as well as the generated electrical power is analyzed with respect to the proper operation range.

  8. Validity and reliability of an alternative method for measuring power output during six-second all-out cycling.

    PubMed

    Watson, Martin; Bibbo, Daniele; Duffy, Charles R; Riches, Philip E; Conforto, Silvia; Macaluso, Andrea

    2014-08-01

    In a laboratory setting where both a mechanically-braked cycling ergometer and a motion analysis (MA) system are available, flywheel angular displacement can be estimated by using MA. The purpose of this investigation was to assess the validity and reliability of a MA method for measuring maximal power output (Pmax) in comparison with a force transducer (FT) method. Eight males and eight females undertook three identical sessions, separated by 4 to 6 days; the first being a familiarization session. Individuals performed three 6-second sprints against 50% of the maximal resistance to complete two pedal revolutions with a 3-minute rest between trials. Power was determined independently using both MA and FT analyses. Validity: MA recorded significantly higher Pmax than FT (P < .05). Bland-Altman plots showed that there was a systematic bias in the difference between the measures of the two systems. This difference increased as power increased. Repeatability: Intraclass correlation coefficients were on average 0.90 ± 0.05 in males and 0.85 ± 0.08 in females. Measuring Pmax by MA, therefore, is as appropriate for use in exercise physiology research as Pmax measured by FT, provided that a bias between these measurements methods is allowed for. PMID:24977624

  9. High output power and high temperature operation of 1. 5 /mu/m DFB-PPIBH laser diodes

    SciTech Connect

    Kakimoto, S.; Nakajima, Y.; Takemoto, A.; Yoshida, N.; Namizaki, H.; Susaki, W.

    1989-06-01

    Highly efficient 1.5 /mu/m distributed feedback p-substrate partially-inverted buried heterostructure laser diodes with a thin active layer have been developed using a metal-organic chemical vapor deposition technique. An average slope efficiency of 0.26 mW/mA (quantum efficiency 33 percent) and the maximum slope efficiency of 0.39 mW/mA (49 percent) were achieved. The full width at half maximum in the direction perpendicular to the junction plane of 25/sup 0/ was obtained. A high output power of 77 mW was obtained under a CW condition at room temperature. This laser diode laser up to 120/sup 0/C, and more than 10 mW was obtained, even at 90/sup 0/C.

  10. High power multi-color OPCPA source with simultaneous femtosecond deep-UV to mid-IR outputs.

    PubMed

    Baudisch, M; Wolter, B; Pullen, M; Hemmer, M; Biegert, J

    2016-08-01

    Many experimental investigations demand synchronized pulses at various wavelengths, ideally with very short pulse duration and high repetition rate. Here we describe a femtosecond multi-color optical parametric chirped pulse amplifier (OPCPA) with simultaneous outputs from the deep-UV to the mid-IR with optical synchronization. The high repetition rate of 160 kHz is well suited to compensate for low interaction probability or low cross section in strong-field interactions. Our source features high peak powers in the tens to hundreds of MW regime with pulse durations below 110 fs, which is ideal for pump-probe experiments of nonlinear and strong-field physics. We demonstrate its utility by strong-field ionization experiments of xenon in the near- to mid-IR. PMID:27472624

  11. Studies of acoustic-electric feed-throughs for power transmission through structures

    NASA Technical Reports Server (NTRS)

    Sherrit, Stewart; Doty, Benjamin; Badescu, Mircea; Bao, Xiaoqi; Bar-Cohen, Yoseph; Aldrich, Jack; Chang, Zensheu

    2006-01-01

    There are numerous engineering design problems where the use of wires to transfer power and communicate data thru the walls of a structure is prohibitive or significantly difficult that it may require a complex design. Using physical feedthroughs in such systems may make them susceptible to leakage of chemicals or gasses, loss of pressure or vacuum, as well as difficulties in providing adequate thermal or electrical insulation. Moreover, feeding wires thru a wall of a structure reduces the strength of the structure and makes the structure prone to cracking due to fatigue that can result from cyclic loading and stress concentrations. One area that has already been identified to require a wireless alternative to electrical feedthroughs is the container of the Mars Sample Return Mission, which will need wireless sensors to sense a pressure leak and to avoid potential contamination. The idea of using elastic or acoustic waves to transfer power was suggested recently by [Y. Hu, et al., July 2003]. This system allows for the avoidance of cabling or wiring. The technology is applicable to the transfer of power for actuation, sensing and other tasks inside any sealed container or vacuum/pressure vessel. An alternative approach to the modeling presented previously [Sherrit et a., 2005] used network analysis to solve the same problem in a clear and expandable manner. Experimental tests on three different designs of these devices were performed. The three designs used different methods of coupling the piezoelectric element to the wall. In the first test the piezoelectric material was bolted using a backing structure. In the second test the piezoelectric was clamped after the application of grease and finally the piezoelectric element was attached using a conductive epoxy. The mechanical clamp with grease produced the highest measured efficiency of 53% however this design was the least practical from a fabrication viewpoint. The power transfer efficiency of conductive epoxy

  12. The effects of time following acute growth hormone administration on metabolic and power output measures during acute exercise.

    PubMed

    Irving, Brian A; Patrie, James T; Anderson, Stacey M; Watson-Winfield, Deidre D; Frick, Kirsten I; Evans, William S; Veldhuis, Johannes D; Weltman, Arthur

    2004-09-01

    We examined the effects of GH infusion on metabolism and performance measures during acute exercise. Nine males [(X+/-SEM): age 23.7+/-1.9 yr, height 182.6+/-1.6 cm, weight 77.3+/- 2.6 kg, percent fat 17.7+/-1.9%, peak oxygen consumption 37.9 +/- 2.9 ml/kg.min] completed six 30-min randomly assigned bicycle ergometer exercise trials at a power output midway between the lactate threshold and peak oxygen consumption. In five of the six trials, the subjects received a recombinant humanGHinfusion (10 microg/kg, 6-min square wave pulse) at 0800 h, followed by a 30-min exercise trial initiated at one of the following times: 0845, 0930, 1015, 1100, or 1145 h. During one of the six trials, the subject received a saline infusion followed by a 30-min exercise trial initiated at 0845 h. Mixed-effect, repeated-measures ANOVA analyses corrected for multiple comparisons revealed that there were no significant condition effects for total work, caloric expenditure, heart rate response, the blood lactate response, or ratings of perceived exertion response. However, acute GH administration resulted in a lower exercise oxygen consumption without a drop-off in power output. We conclude that the time of exercise initiation after GH infusion does not affect total work, caloric expenditure, heart rate response, blood lactate response, or ratings of perceived exertion but reduces oxygen consumption in response to 30 min of constant load exercise at an intensity above the lactate threshold. The last outcome may suggest that GH administration can improve exercise economy.

  13. Human diaphragm efficiency estimated as power output relative to activation increases with hypercapnic hyperpnea.

    PubMed

    Finucane, Kevin E; Singh, Bhajan

    2009-11-01

    Hyperpnea with exercise or hypercapnia causes phasic contraction of abdominal muscles, potentially lengthening the diaphragm at end expiration and unloading it during inspiration. Muscle efficiency in vitro varies with load, fiber length, and precontraction stretch. To examine whether these properties of muscle contractility determine diaphragm efficiency (Eff(di)) in vivo, we measured Eff(di) in six healthy adults breathing air and during progressive hypercapnia at three levels of end-tidal Pco(2) with mean values of 48 (SD 2), 55 (SD 2), and 61 (SD 1) Torr. Eff(di) was estimated as the ratio of diaphragm power (Wdi) [the product of mean inspiratory transdiaphragmatic pressure, diaphragm volume change (DeltaVdi) measured fluoroscopically, and 1/inspiratory duration (Ti(-1))] to activation [root mean square values of inspiratory diaphragm electromyogram (RMS(di)) measured from esophageal electrodes]. At maximum hypercapnea relative to breathing air, 1) gastric pressure and diaphragm length at end expiration (Pg(ee) and Ldi(ee), respectively) increased 1.4 (SD 0.2) and 1.13 (SD 0.08) times, (P < 0.01 for both); 2) inspiratory change (Delta) in Pg decreased from 4.5 (SD 2.2) to -7.7 (SD 3.8) cmH(2)O (P < 0.001); 3) DeltaVdi.Ti(-1), Wdi, RMS(di), and Eff(di) increased 2.7 (SD 0.6), 4.9 (SD 1.8), 2.6 (SD 0.9), and 1.8 (SD 0.3) times, respectively (P < 0.01 for all); and 4) net and inspiratory Wdi were not different (P = 0.4). Eff(di) was predicted from Ldi(ee) (P < 0.001), Pg(ee) (P < 0.001), DeltaPg.Ti(-1) (P = 0.03), and DeltaPg (P = 0.04) (r(2) = 0.52) (multivariate regression analysis). We conclude that, with hypercapnic hyperpnea, 1) approximately 47% of the maximum increase of Wdi was attributable to increased Eff(di); 2) Eff(di) increased due to preinspiratory lengthening and inspiratory unloading of the diaphragm, consistent with muscle behavior in vitro; 3) passive recoil of the diaphragm did not contribute to inspiratory Wdi or Eff(di); and 4) phasic

  14. Digital stroboscopic holographic interferometry for power flow measurements in acoustically driven membranes

    NASA Astrophysics Data System (ADS)

    Keustermans, William; Pires, Felipe; De Greef, Daniël; Vanlanduit, Steve J. A.; Dirckx, Joris J. J.

    2016-06-01

    Despite the importance of the eardrum and the ossicles in the hearing chain, it remains an open question how acoustical energy is transmitted between them. Identifying the transmission path at different frequencies could lead to valuable information for the domain of middle ear surgery. In this work a setup for stroboscopic holography is combined with an algorithm for power flow calculations. With our method we were able to accurately locate the power sources and sinks in a membrane. The setup enabled us to make amplitude maps of the out-of-plane displacement of a vibrating rubber membrane at subsequent instances of time within the vibration period. From these, the amplitude maps of the moments of force and velocities are calculated. The magnitude and phase maps are extracted from this amplitude data, and form the input for the power flow calculations. We present the algorithm used for the measurements and for the power flow calculations. Finite element models of a circular plate with a local energy source and sink allowed us to test and optimize this algorithm in a controlled way and without the present of noise, but will not be discussed below. At the setup an earphone was connected with a thin tube which was placed very close to the membrane so that sound impinges locally on the membrane, hereby acting as a local energy source. The energy sink was a little piece of foam carefully placed against the membrane. The laser pulses are fired at selected instants within the vibration period using a 30 mW HeNe continuous wave laser (red light, 632.8 nm) in combination with an acousto-optic modulator. A function generator controls the phase of these illumination pulses and the holograms are recorded using a CCD camera. We present the magnitude and phase maps as well as the power flow measurements on the rubber membrane. Calculation of the divergence of this power flow map provides a simple and fast way of identifying and locating an energy source or sink. In conclusion

  15. An ultra-low power and flexible acoustic modem design to develop energy-efficient underwater sensor networks.

    PubMed

    Sánchez, Antonio; Blanc, Sara; Yuste, Pedro; Perles, Angel; Serrano, Juan José

    2012-01-01

    This paper is focused on the description of the physical layer of a new acoustic modem called ITACA. The modem architecture includes as a major novelty an ultra-low power asynchronous wake-up system implementation for underwater acoustic transmission that is based on a low-cost off-the-shelf RFID peripheral integrated circuit. This feature enables a reduced power dissipation of 10 μW in stand-by mode and registers very low power values during reception and transmission. The modem also incorporates clear channel assessment (CCA) to support CSMA-based medium access control (MAC) layer protocols. The design is part of a compact platform for a long-life short/medium range underwater wireless sensor network.

  16. An Ultra-Low Power and Flexible Acoustic Modem Design to Develop Energy-Efficient Underwater Sensor Networks

    PubMed Central

    Sánchez, Antonio; Blanc, Sara; Yuste, Pedro; Perles, Angel; Serrano, Juan José

    2012-01-01

    This paper is focused on the description of the physical layer of a new acoustic modem called ITACA. The modem architecture includes as a major novelty an ultra-low power asynchronous wake-up system implementation for underwater acoustic transmission that is based on a low-cost off-the-shelf RFID peripheral integrated circuit. This feature enables a reduced power dissipation of 10 μW in stand-by mode and registers very low power values during reception and transmission. The modem also incorporates clear channel assessment (CCA) to support CSMA-based medium access control (MAC) layer protocols. The design is part of a compact platform for a long-life short/medium range underwater wireless sensor network. PMID:22969324

  17. Resonantly pumped monolithic nonplanar Ho:YAG ring laser with high-power single-frequency laser output at 2122 nm.

    PubMed

    Wang, Lei; Gao, Chunqing; Gao, Mingwei; Li, Yan

    2013-04-22

    We demonstrated a stable single-frequency laser operating at 2122 nm from a monolithic nonplanar Ho:YAG ring oscillator (NPRO). The Ho:YAG NPRO was resonantly pumped by a 1907 nm Tm:YLF laser built up by ourselves. The maximum multimode output power from the Ho:YAG NPRO was 9.66 W and the slope efficiency was 71.7%. With accurate adjustment of the pump position to make the laser oscillate in single frequency condition, an output power of 8.0 W was obtained with a slope efficiency of 61.4% and an optical-optical efficiency of 50.0%. The power stability of the Ho:YAG NPRO laser was 0.29% at maximum single frequency output power. The beam quality M(2) factors were measured to be less than 1.1 in x- and y- directions.

  18. Influence of Affective Stimuli on Leg Power Output and Associated Neuromuscular Parameters during Repeated High Intensity Cycling Exercises

    PubMed Central

    Jaafar, Hamdi; Rouis, Majdi; Coudrat, Laure; Gélat, Thierry; Noakes, Timothy David; Driss, Tarak

    2015-01-01

    The aim of this study was to examine the impact of emotional eliciting pictures on neuromuscular performance during repetitive supramaximal cycling exercises (RSE). In a randomized order, twelve male participants were asked to perform five 6-s cycle sprints (interspaced by 24 s of recovery) on a cycle ergometer in front of neutral, pleasant or unpleasant pictures. During each RSE, mean power output (MPO) and electromyographic activity [root mean square (RMS) and median frequency (MF)] of the vastus lateralis and vastus medialis muscles were analyzed. Neuromuscular efficiency (NME) was calculated as the ratio of MPO to RMS. Higher RMS (232.17 ± 1.17 vs. 201.90 ± 0.47 μV) and MF (68.56 ± 1.78 vs. 64.18 ± 2.17 Hz) were obtained in pleasant compared to unpleasant conditions (p < 0.05). This emotional effect persisted from the first to the last sprint. Higher MPO was obtained in pleasant than in unpleasant conditions (690.65 ± 38.23 vs. 656.73 ± 35.95 W, p < 0.05). However, this emotional effect on MPO was observed only for the two first sprints. NME decreased from the third sprint (p < 0.05), which indicated the occurrence of peripheral fatigue after the two first sprints. These results suggested that, compared with unpleasant pictures, pleasant ones increased the neuromuscular performance during RSE. Moreover, the disappearance of the beneficial effect of pleasant emotion on mechanical output from the third sprint appears to be due to peripheral fatigue. PMID:26305334

  19. An 8 channel, 20 V output CMOS switching driver with 3.3 V power supply using triple-well biasing techniques for integrated MEMS device control

    NASA Astrophysics Data System (ADS)

    Takayasu, Motohiro; Shirane, Atsushi; Lee, Sangyeop; Yamane, Daisuke; Ito, Hiroyuki; Mi, Xiaoyu; Inoue, Hiroaki; Nakazawa, Fumihiko; Ueda, Satoshi; Ishihara, Noboru; Masu, Kazuya

    2014-01-01

    An 8 channel output switching driver has been implemented for integrated micro-electro-mechanical systems (MEMS) device control using the 0.18 µm CMOS process technology. The driver can output 20 V switching signals for 1 nF capacitive loads with a 3.3 V power supply. The switching time is less than 100 µs. To obtain a high output voltage that exceeds the transistors’ and capacitors’ breakdown voltages, a new charge pump and a discharge circuit, using optimal transistor-well-biasing techniques for triple-well-structured n-MOS transistors, were investigated, and the circuit parameters were also optimized to obtain high-speed switching.

  20. Anaerobic and aerobic peak power output and the force-velocity relationship in endurance-trained athletes: effects of aging.

    PubMed

    Chamari, K; Ahmaidi, S; Fabre, C; Massé-Biron, J; Préfaut, C

    1995-01-01

    The aim of this investigation was to test the hypothesis that the anaerobic peak power output (Pan, peak) declines more than the peak aerobic power (Paer, peak) with increasing age. In addition, the force-velocity (F-v) relationship was studied to determine which of these two factors is primarily responsible for the expected alterations in anaerobic power. The Pan, peak, the maximal F when v is equal to zero (F0) and the maximal v when F is equal to zero (v0) were assessed by F-v test i.e. a brief intense intermittent exercise test using incremental braking forces. The Paer, peak was measured by a maximal increment exercise test. A group of 12 young athletes (YA) and 12 master athletes (MA) mean age 24.8 (SEM 1.3) and 65.1 (SEM 1.2) years, respectively, participated in this study. The YA and MA had similar body masses, heights and endurance training schedules. The results showed that Pan, peak was 42.7% lower in the older subjects, corresponding to mean values of 1089 (SEM 40) compared to 624 (SEM 33) W (t = 8.9, P < 0.001) for YA compared to MA, respectively. The F0 and V0 indices showed values that were lower by 30.3% and 15.2%, respectively. The Paer, peak was 35% lower with mean values of 323 (SEM 12) W for YA compared to 210 (SEM 6) W for MA (t = 8.3, P < 0.001). The mean maximal oxygen uptake was 34.7% lower with 4240 (SEM 160) ml.min-1 for YA compared to 2770 (SEM 120) ml.min-1 for MA (t = 7.2, P < 0.001).(ABSTRACT TRUNCATED AT 250 WORDS)

  1. Effects of short-term training using SmartCranks on cycle work distribution and power output during cycling.

    PubMed

    Böhm, Harald; Siebert, Stefan; Walsh, Mark

    2008-05-01

    SmartCranks use a free running bearing to promote independent pedal work by each leg during cycling. This system is designed for training the upstroke phase during cycling. The effects of training with SmartCranks on the power output (PO) and on cycle work distribution at the anaerobic threshold and the maximum power level were examined. Twenty male, non-professional cyclists were randomly assigned into intervention and control group, training 5 weeks with SmartCranks and conventional cranks, respectively. Before and after the training period the subjects performed an incremental test to exhaustion. Lactate was measured to determine the individual anaerobic threshold (IAT) and forces at the pedal were recorded to quantify changes in the work distribution over the full revolution. We observed no significant statistical difference for peak power (PO; 333.3+/-32.8 W vs. 323.3+/-21.8 W) and PO at IAT (229.6+/-30.1 W vs. 222.7+/-25.2 W) for SmartCrank and control conditions, respectively (P>0.05). However, we did observe that work distribution in the downward phase was significantly reduced in the SmartCranks training group at peak PO (from 70.0+/-4.9% to 64.3+/-5.8%; P<0.05). Although the possible implications of the change in the work distribution of sectors are not known, for the success in cycling performance-indicated by the PO-training with the SmartCranks was not more advantageous than training with conventional bicycle cranks.

  2. Acoustic emission descriptors

    NASA Astrophysics Data System (ADS)

    Witos, Franciszek; Malecki, Ignacy

    The authors present selected problems associated with acoustic emission interpreted as a physical phenomenon and as a measurement technique. The authors examine point sources of acoustic emission in isotropic, homogeneous linearly elastic media of different shapes. In the case of an unbounded medium the authors give the analytical form of the stress field and the wave shift field of the acoustic emission. In the case of a medium which is unbounded plate the authors give a form for the equations which is suitable for numerical calculation of the changes over time of selected acoustic emission values. For acoustic emission as a measurement technique, the authors represent the output signal as the resultant of a mechanical input value which describes the source, the transient function of the medium, and the transient function of specific components of the measurement loop. As an effect of this notation, the authors introduce the distinction between an acoustic measurement signal and an acoustic measurement impulse. The authors define the basic parameters of an arbitrary impulse. The authors extensively discuss the signal functions of acoustic emission impulses and acoustic emission signals defined in this article as acoustic emission descriptors (or signal functions of acoustic emission impulses) and advanced acoustic emission descriptors (which are either descriptors associated with acoustic emission applications or the signal functions of acoustic emission signals). The article also contains the results of experimental research on three different problems in which acoustic emission descriptors associated with acoustic emission pulses, acoustic emission applications, and acoustic emission signals are used. These problems are respectively: a problem of the amplitude-load characteristics of acoustic emission pulses in carbon samples subjected to compound uniaxial compression, the use of acoustic emission to predict the durability characteristics of conveyor belts, and

  3. Problems in Assessment of Wind Energy Potential and Acoustic Noise Distribution when Designing Wind Power Plants

    NASA Astrophysics Data System (ADS)

    Bezrukovs, Valerijs; Bezrukovs, Vladislavs; Levins, Nikolajs

    2011-01-01

    Interest in the use of renewable energy in Latvia is increasing every year. Government support and availability of large unpopulated areas on the coast makes the use of these lands for the placement of large wind power plants (WPP) attractive. The key factors that determine the choice of the location of WPP are reliable information about distribution of the resource of wind energy in this area and the influence of wind turbines on the environment. The paper presents the results of years-long observations on the density fluctuations of wind energy at heights of 10 to 60 m in the area in the Baltic Sea coast in Ventspils and Ainaži. The velocity observations since 2007 have been gathered by measurements complex of the LOGGER 9200 Symphonie type. The results are presented in the form of tables, bar charts and graphs. Extrapolation results of wind velocity and density mean values on heights up to 150 m for the two areas with different terrain types were shown. The distribution of acoustic noise in the vicinity of the WPP was studied and an assessment of its impact on the environment in accordance with the Latvian government requirements was conducted.

  4. MONITORING POWER PLANT EFFICIENCY USING THE MICROWAVE-EXCITED THERMAL-ACOUSTIC EFFECT TO MEASURE UNBURNED CARBON

    SciTech Connect

    Robert C. Brown; Robert J. Weber; Jeffrey J. Swetelitsch

    2005-01-01

    The objective of this project is to explore microwave-excited thermal-acoustic (META) phenomena for quantitative analysis of granular and powdered materials, with the culmination of the research to be an on-line carbon-in-ash monitor for coal-fired power plants. This technique of analyzing unburned carbon in fly ash could be a less tedious and time consuming method as compared to the traditional LOI manual procedure. Phase 1 of the research focused on off-line single-frequency thermal-acoustic measurements where an off-line fly ash monitor was constructed that could operate as analytical tool to explore instrument and methodology parameters for quantifying the microwave-excited thermal-acoustic effect of carbon in fly ash, and it was determined that the off-line thermal-acoustic technique could predict the carbon content of a random collection of fly ashes with a linear correlation constant of R{sup 2} = 0.778. Much higher correlations are expected for fly ashes generated from a single boiler. Phase 2 of the research developing a methodology to generate microwave spectra of various powders, including fly ash, coal, and inorganic minerals, and to determine if these microwave spectra could be used for chemical analyses. Although different minerals produced different responses, higher resolution microwave spectra would be required to be able to distinguish among minerals. Phase 3 of the research focused on the development of an on-line fly ash monitor that could be adapted to measure either a thermal-acoustic or thermal-elastic response to due microwave excitation of fly ash. The thermal-acoustic response was successfully employed for this purpose but the thermal-elastic response was too weak to yield a useful on-line device.

  5. Design of a high voltage input - output ratio dc-dc converter dedicated to small power fuel cell systems

    NASA Astrophysics Data System (ADS)

    Béthoux, O.; Cathelin, J.

    2010-12-01

    Consuming chemical energy, fuel cells produce simultaneously heat, water and useful electrical power [J.M. Andújar, F. Segura, Renew. Sust. Energy Rev. 13, 2309 (2009)], [J. Larminie, A. Dicks, Fuel Cell Systems Explained, 2nd edn. (John Wiley & Sons, 2003)]. As a matter of fact, the voltage generated by a fuel cell strongly depends on both the load power demand and the operating conditions. Besides, as a result of many design aspects, fuel cells are low voltage and high current electric generators. On the contrary, electric loads are commonly designed for small voltage swing and a high V/I ratio in order to minimize Joule losses. Therefore, electric loads supplied by fuel cells are typically fed by means of an intermediate power voltage regulator. The specifications of such a power converter are to be able to step up the input voltage with a high ratio (a ratio of 10 is a classic situation) and also to work with an excellent efficiency (in order to minimize its size, its weight and its losses) [A. Shahin, B. Huang, J.P. Martin, S. Pierfederici, B. Davat, Energy Conv. Manag. 51, 56 (2010)]. This paper deals with the design of this essential ancillary device. It intends to bring out the best structure for fulfilling this function. Several dc-dc converters with large voltage step-up ratios are introduced. A topology based on a coupled inductor or tapped inductor is closely studied. A detailed modelling is performed with the purpose of providing designing rules. This model is validated with both simulation and implementation. The experimental prototype is based on the following specifications: the fuel cell output voltage ranges from a 50 V open-voltage to a 25 V rated voltage while the load requires a constant 250 V voltage. The studied coupled inductor converter is compared with a classic boost converter commonly used in this voltage elevating application. Even though the voltage regulator faces severe FC specifications, the measured efficiency reaches 96% at the

  6. Short-term power output and local muscular endurance of young male soccer players according to playing position.

    PubMed

    Nikolaïdis, Pantelis Theodoros

    2014-06-01

    Although the contribution of anaerobic power in soccer performance is recognized and there is evidence that many anthropometric and physiological characteristics vary according to playing position, the association between playing position and short-term power output, and local muscular endurance is not well studied, especially in young players. Therefore, the aim of the present study is to examine whether this component of sport-related physical fitness of young soccer players varies according to playing position. Young male (N = 296; aged 10.94-21.00 y), classified in five two-year age-groups, and adults (N = 30; aged 21.12-31.59 y), all members of competitive soccer clubs, performed the 30-s Wingate anaerobic test against braking force 0.075 kg x kg(-1) of body mass. One-way analysis of variance (ANOVA) revealed significant differences between age groups with regard to peak power in absolute, P(peak) (F5,320 = 86.7, p < 0.001), and in relative to body mass values, rP(peak) (F5,320 = 43.27, p < 0.001), mean power in absolute, P(mean) (F5,313 = 108.97, p < 0.001), and in relative values, rP(mean) (F5,313 = 41.64, p < 0.001), while there was no difference with respect to fatigue index, FI (F5,312 = 1.09, p = 0.370). One-way analysis of covariance, considering age as covariate, did not reveal any significant differences among playing position groups with regard to P(peak) (F3,289 = 1.46, p = 0.226), rP(peak) (F3,289 = 0.87, p = 0.457) and P(mean) (F3,283 = 0.31, p = 0.817), while goalkeepers had lower rP(mean) than defenders, midfielders and forwards (F3,283 = 6.32, p < 0.001). One-way ANOVA revealed differences with regard to FI (F3,283 = 5.97, p < 0.001), according to which goalkeepers had higher values than defenders and midfielders. Compared with data from previous studies in general population, participants had superior short-term power output and local muscular endurance. Both these anaerobic parameters were in direct relationship with age (r = 0.64, p < 0

  7. All-solid-state continuous-wave frequency doubling Nd:LuVO4/LBO laser with 2.17 W output power at 543 nm

    NASA Astrophysics Data System (ADS)

    Li, B.; Zhao, L.; Zhang, Y. B.; Zheng, Q.; Zhao, Y.; Yao, Y.

    2013-03-01

    Efficient and compact green-yellow laser output at 543 nm is generated by intracavity frequency doubling of a CW diode-pumped Nd:LuVO4 laser at 1086 nm under the condition of suppressing the higher gain transition near 1064 nm. With 16 W of diode pump power and the frequency-doubling crystal LBO, as high as 2.17 W of CW output power at 543 nm is achieved, corresponding to an optical-to-optical conversion efficiency of 13.6% and the output power stability over 8 hours is better than 2.86%. To the best of our knowledge, this is the highest watt-level laser at 543 nm generated by intracavity frequency doubling of a diode pumped Nd:LuVO4 laser at 1086 nm.

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

    PubMed

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

    2016-03-20

    In this paper we discuss how different feedback gratings affect the tuning range and the output power of external feedback diode laser systems. A tunable high-power narrow-spectrum external-cavity diode laser system around 455 nm is investigated. The laser system is based on a high-power GaN diode laser in a Littrow external-cavity. Both a holographic diffraction grating and a ruled diffraction grating are used as feedback elements in the external cavity. The output power, spectral bandwidth, and tunable range of the external cavity diode laser system are measured and compared with the two gratings at different injected currents. When the holographic grating is used, the laser system can be tuned over a range of 1.4 nm with an output power around 530 mW. When the ruled grating is used, the laser system can be tuned over a range of 6.0 nm with an output power around 80 mW. The results can be used as a guide for selecting gratings for external-cavity diode lasers for different requirements. PMID:27140561

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

    PubMed

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

    2016-03-20

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

  10. A dual-mode operation overmoded coaxial millimeter-wave generator with high power capacity and pure transverse electric and magnetic mode output

    NASA Astrophysics Data System (ADS)

    Bai, Zhen; Zhang, Jun; Zhong, Huihuang

    2016-04-01

    An overmoded coaxial millimeter-wave generator with high power capacity and pure transverse electric and magnetic (TEM) mode output is designed and presented, by using a kind of coaxial slow wave structure (SWS) with large transversal dimension and small distance between inner and outer conductors. The generator works in dual-mode operation mechanism. The electron beam synchronously interacts with 7π/8 mode of quasi-TEM, at the meanwhile exchanges energy with 3π/8 mode of TM01. The existence of TM01 mode, which is traveling wave, not only increases the beam-wave interaction efficiency but also improves the extraction efficiency. The large transversal dimension of coaxial SWS makes its power capacity higher than that of other reported millimeter-wave devices and the small distance between inner and outer conductors allows only two azimuthally symmetric modes to coexist. The converter after the SWS guarantees the mode purity of output power. Particle-in-cell simulation shows that when the diode voltage is 400 kV and beam current is 3.8 kA, the generation of microwave at 32.26 GHz with an output power of 611 MW and a conversion efficiency of 40% is obtained. The power percentage carried by TEM mode reaches 99.7% in the output power.

  11. The effects of liquid height/volume, initial concentration of reactant and acoustic power on sonochemical oxidation.

    PubMed

    Lim, Myunghee; Ashokkumar, Muthupandian; Son, Younggyu

    2014-11-01

    Even though much knowledge on acoustic cavitation and its application has been accumulated over the past decades, further research is still required to develop industrial uses of acoustic cavitation. It is because the available information is mainly based on small-scale sonoreactors and the design and optimization of sonoreactors for large-scale applications have not been widely studied. In this study, the effects of liquid height/volume, initial concentration of the reactant and input acoustic power on sonochemical oxidation reactions including iodide ion oxidation, As(III) oxidation, and hydrogen peroxide generation were investigated using a 291kHz sonoreactor with various liquid height/volumes (50, 100, 200, 300, 500, and 1000mL) and input powers (23, 40, and 82W). As the liquid height/volume and the input power changed, the power density varied from 23 to 1640W/L and the maximum cavitation yields of triiodide ion for 23, 40, and 82W were observed at 0.05, 0.1, and 0.2/0.3L, respectively. It was found that low power was more effective for the small volume and the large volume required high power level and the moderate power density, approximately 400W/L, was suggested for the sonochemical oxidation of iodide ion in the 291kHz sonoreactor in this study. Similar results were observed in the generation of hydrogen peroxide and the sonochemical oxidation of As(III) to As(V). It was also revealed that KI dosimetry could be applicable for the estimation of the sonochemical reactions of non-volatile compounds such as As(III).

  12. Picosecond laser with 11 W output power at 1342 nm based on composite multiple doping level Nd:YVO4 crystal

    NASA Astrophysics Data System (ADS)

    Rodin, Aleksej M.; Grishin, Mikhail; Michailovas, Andrejus

    2016-01-01

    We report results of design and optimization of high average output power picosecond and nanosecond laser operating at 1342 nm wavelength. Developed for selective micromachining, this DPSS laser is comprised of master oscillator, regenerative amplifier and output pulse control module. Passively mode-locked by means of semiconductor saturable absorber mirror and pumped with 808 nm wavelength Nd:YVO4 master oscillator emits 12.5 ps pulses at repetition rate of 55 MHz with average output power of ∼100 mW. The four-pass confocal delay line forms a longest part of the oscillator cavity in order to suppress thermo-mechanical misalignment. Picked from the train seed pulses were injected to the cavity of regenerative amplifier based on composite Nd:YVO4 crystal with diffusion-bonded segments of multiple Nd doping concentration end-pumped at 880 nm wavelength. Laser produces pulses of ∼13 ps duration at 300 kHz repetition rate with average output power of 11 W and nearly diffraction limited beam quality of M2∼1.03. Attained high peak power ∼2.8 MW facilitates conversion to the 2nd, 3rd and 6th harmonics at 671 nm, 447 nm and 224 nm wavelengths with 80%, 50% and 15% efficiency respectively. Without seeding the regenerative amplifier transforms to electro-optically cavity-dumped Q-switched laser providing 10 ns output pulses at high repetition rates with beam propagation factor of M2∼1.06.

  13. Simultaneous backward data transmission and power harvesting in an ultrasonic transcutaneous energy transfer link employing acoustically dependent electric impedance modulation.

    PubMed

    Ozeri, Shaul; Shmilovitz, Doron

    2014-09-01

    The advancement and miniaturization of body implanted medical devices pose several challenges to Ultrasonic Transcutaneous Energy Transfer (UTET), such as the need to reduce the size of the piezoelectric resonator, and the need to maximize the UTET link power-transfer efficiency. Accordingly, the same piezoelectric resonator that is used for energy harvesting at the body implant, may also be used for ultrasonic backward data transfer, for instance, through impedance modulation. This paper presents physical considerations and design guidelines of the body implanted transducer of a UTET link with impedance modulation for a backward data transfer. The acoustic matching design procedure was based on the 2×2 transfer matrix chain analysis, in addition to the Krimholtz Leedom and Matthaei KLM transmission line model. The UTET power transfer was carried out at a frequency of 765 kHz, continuous wave (CW) mode. The backward data transfer was attained by inserting a 9% load resistance variation around its matched value (550 Ohm), resulting in a 12% increase in the acoustic reflection coefficient. A backward data transmission rate of 1200 bits/s was experimentally demonstrated using amplitude shift keying, simultaneously with an acoustic power transfer of 20 mW to the implant. PMID:24861424

  14. Simultaneous backward data transmission and power harvesting in an ultrasonic transcutaneous energy transfer link employing acoustically dependent electric impedance modulation.

    PubMed

    Ozeri, Shaul; Shmilovitz, Doron

    2014-09-01

    The advancement and miniaturization of body implanted medical devices pose several challenges to Ultrasonic Transcutaneous Energy Transfer (UTET), such as the need to reduce the size of the piezoelectric resonator, and the need to maximize the UTET link power-transfer efficiency. Accordingly, the same piezoelectric resonator that is used for energy harvesting at the body implant, may also be used for ultrasonic backward data transfer, for instance, through impedance modulation. This paper presents physical considerations and design guidelines of the body implanted transducer of a UTET link with impedance modulation for a backward data transfer. The acoustic matching design procedure was based on the 2×2 transfer matrix chain analysis, in addition to the Krimholtz Leedom and Matthaei KLM transmission line model. The UTET power transfer was carried out at a frequency of 765 kHz, continuous wave (CW) mode. The backward data transfer was attained by inserting a 9% load resistance variation around its matched value (550 Ohm), resulting in a 12% increase in the acoustic reflection coefficient. A backward data transmission rate of 1200 bits/s was experimentally demonstrated using amplitude shift keying, simultaneously with an acoustic power transfer of 20 mW to the implant.

  15. Fourfold output power enhancement and threshold reduction through thermal effects in an Er(3+)/Yb(3+)-codoped optical fiber laser excited at 1.064 mum.

    PubMed

    da Silva, C J; de Araujo, M T; Gouveia, E A; Gouveia-Neto, A S

    1999-09-15

    Thermally induced output power enhancement and threshold reduction in an Er(3+)/Yb(3+) -codoped optical fiber laser at 1.54mum pumped by 1.064-mu;m cw radiation is demonstrated. Steady fourfold output power increase and threshold decrease were achieved by heating of the Yb(3+) -sensitized Er(3+) -doped fiber laser medium in the temperature range 23-150 degrees C degrees . The laser efficiency thermal behavior is assigned to the temperature-dependent effective absorption cross section of the ytterbium sensitizer through the so-called multiphonon-assisted anti-Stokes excitation process. PMID:18079782

  16. The effects of circadian rhythmicity of salivary cortisol and testosterone on maximal isometric force, maximal dynamic force, and power output.

    PubMed

    Teo, Weipeng; McGuigan, Michael R; Newton, Michael J

    2011-06-01

    The study investigated the effects of circadian rhythm of cortisol (C) and testosterone (T) on maximal force production (Fpeak) and power output (Ppeak). Twenty male university students (mean age = 23.8 ± 3.6 years, height = 177.5 ± 6.4 cm, weight = 78.9 ± 11.2 kg) performed 4 time-of-day testing sessions consisting of countermovement jumps (CMJs), squat jumps (SJ), isometric midthigh pulls (IMTPs), and a 1-repetition maximum (1RM) squat. Saliva samples were collected at 0800, 1200, 1600, and 2000 hours to assess T and C levels on each testing day. Session rate-of-perceived exertion (RPE) scores were collected after each session. The results showed that Fpeak and Ppeak presented a clear circadian rhythm in CMJ and IMTP but not in SJ. One repetition maximum squat did not display a clear circadian rhythm. Session RPE scores collected at 0800 and 2000 hours were significantly (p ≤ 0.05) higher than those obtained at 1200 and 1600 hours. Salivary T and C displayed a clear circadian rhythm with highest values at 0800 hours and lowest at 2000 hours; however, no significant correlation was found between T and C with Fpeak and Ppeak. A very strong correlation was found between Taural with Fpeak of CMJ and IMTP and Ppeak of CMJ (r = 0.86, r = 0.84 and r = 0.8, p ≤ 0.001). The study showed the existence of a circadian rhythm in Fpeak and Ppeak in CMJ and IMTP. The evidence suggests that strength and power training or testing should be scheduled later during the day. The use of Taural seemed to be a more effective indicator of physical performance than hormonal measures, and the use of session RPE should also be closely monitored because it may present a circadian rhythm.

  17. Reversible swarming and separation of self-propelled chemically powered nanomotors under acoustic fields.

    PubMed

    Xu, Tailin; Soto, Fernando; Gao, Wei; Dong, Renfeng; Garcia-Gradilla, Victor; Magaña, Ernesto; Zhang, Xueji; Wang, Joseph

    2015-02-18

    The collective behavior of biological systems has inspired efforts toward the controlled assembly of synthetic nanomotors. Here we demonstrate the use of acoustic fields to induce reversible assembly of catalytic nanomotors, controlled swarm movement, and separation of different nanomotors. The swarming mechanism relies on the interaction between individual nanomotors and the acoustic field, which triggers rapid migration and assembly around the nearest pressure node. Such on-demand assembly of catalytic nanomotors is extremely fast and reversible. Controlled movement of the resulting swarm is illustrated by changing the frequency of the acoustic field. Efficient separation of different types of nanomotors, which assemble in distinct swarming regions, is illustrated. The ability of acoustic fields to regulate the collective behavior of catalytic nanomotors holds considerable promise for a wide range of practical applications. PMID:25634724

  18. Wireless acoustic-electric feed-through for power and signal transmission

    NASA Technical Reports Server (NTRS)

    Sherrit, Stewart (Inventor); Bar-Cohen, Yoseph (Inventor); Bao, Xiaoqi (Inventor); Doty, Benjamin (Inventor); Badescu, Mircea (Inventor); Chang, Zensheu (Inventor)

    2011-01-01

    An embodiment provides electrical energy from a source on one side of a medium to a load on the other side of the medium, the embodiment including a first piezoelectric to generate acoustic energy in response to electrical energy from the source, and a second piezoelectric to convert the received acoustic energy to electrical energy used by the load. Other embodiments are described and claimed.

  19. Mid-infrared, external cavity BaWO4 Raman laser at 2602 nm with 1.25-W output power

    NASA Astrophysics Data System (ADS)

    Kuzucu, Onur

    2016-03-01

    An external cavity BaWO4 Raman source pumped by a Q-switched Ho:YAG laser is demonstrated. Watt-level average output power is generated at the first Stokes wavelength of 2602 nm. Output pulse width as short as 8.5 ns was measured at a repetition rate of 5 kHz. Near-diffraction limited beam quality is observed (M2≈1.2). This simplified Raman laser configuration can harness the high average power levels offered by Thulium- and Holmium-doped solid-state and fiber lasers to generate fixed-wavelength and tunable output at 2.3-2.8 μm interval.

  20. Study on a Simple Method for Controlling the Engine Output Power of Hybrid Powered Railway Vehicles with Electric Double Layer Capacitors

    NASA Astrophysics Data System (ADS)

    Okano, Shota; Shibuya, Hiroyuki; Kondo, Keiichiro

    This paper presents a simple and energy-saving method for controlling hybrid powered railway vehicles that run on rural non-electrified railway lines and have diesel engine and electrical double layer capacitors (EDLCs). The aim this study is to reduce both the fuel consumption and the capacitance of EDLCs. A basic idea proposed in this paper is that EDLCs supply and absorb the kinetic energy of the vehicle and the engine output compensates supply the energy loss with the vehicle running. Thus, the energy loss is not taken into consideration while expressing the EDLC voltage reference (equation 1); energy loss is considered when the engine is in operating mode. The proposed method is examined by performing numerical simulations for various values of engine operation time, load, and grade section. The results of this study reveal the relationship between the capacitance of the EDLCs and the fuel consumption. Using this proposed control methods, excessive charging of EDLCs can be avoided. The results of this study are expected to expedite the development of energy-saving railway vehicles for the non-electrified lines. Finally, the results of this study increase the possibility of developing hybrid powered railway vehicles.

  1. The acute effect of upper-body complex training on power output of martial art athletes as measured by the bench press throw exercise.

    PubMed

    Liossis, Loudovikos Dimitrios; Forsyth, Jacky; Liossis, Ceorge; Tsolakis, Charilaos

    2013-12-18

    The purpose of this study was to examine the acute effect of upper body complex training on power output, as well as to determine the requisite preload intensity and intra-complex recovery interval needed to induce power output increases. Nine amateur-level combat/martial art athletes completed four distinct experimental protocols, which consisted of 5 bench press repetitions at either: 65% of one-repetition maximum (1RM) with a 4 min rest interval; 65% of 1RM with an 8 min rest; 85% of 1RM with a 4 min rest; or 85% of 1RM with an 8 min rest interval, performed on different days. Before (pre-conditioning) and after (post-conditioning) each experimental protocol, three bench press throws at 30% of 1RM were performed. Significant differences in power output pre-post conditioning were observed across all experimental protocols (F=26.489, partial eta2=0.768, p=0.001). Mean power output significantly increased when the preload stimulus of 65% 1RM was matched with 4 min of rest (p=0.001), and when the 85% 1RM preload stimulus was matched with 8 min of rest (p=0.001). Moreover, a statistically significant difference in power output was observed between the four conditioning protocols (F= 21.101, partial eta(2)=0.913, p=0.001). It was concluded that, in complex training, matching a heavy preload stimulus with a longer rest interval, and a lighter preload stimulus with a shorter rest interval is important for athletes wishing to increase their power production before training or competition.

  2. Surface morphology and surface energy of anode materials influence power outputs in a multi-channel mediatorless bio-photovoltaic (BPV) system.

    PubMed

    Bombelli, Paolo; Zarrouati, Marie; Thorne, Rebecca J; Schneider, Kenneth; Rowden, Stephen J L; Ali, Akin; Yunus, Kamran; Cameron, Petra J; Fisher, Adrian C; Ian Wilson, D; Howe, Christopher J; McCormick, Alistair J

    2012-09-21

    Bio-photovoltaic cells (BPVs) are a new photo-bio-electrochemical technology for harnessing solar energy using the photosynthetic activity of autotrophic organisms. Currently power outputs from BPVs are generally low and suffer from low efficiencies. However, a better understanding of the electrochemical interactions between the microbes and conductive materials will be likely to lead to increased power yields. In the current study, the fresh-water, filamentous cyanobacterium Pseudanabaena limnetica (also known as Oscillatoria limnetica) was investigated for exoelectrogenic activity. Biofilms of P. limnetica showed a significant photo response during light-dark cycling in BPVs under mediatorless conditions. A multi-channel BPV device was developed to compare quantitatively the performance of photosynthetic biofilms of this species using a variety of different anodic conductive materials: indium tin oxide-coated polyethylene terephthalate (ITO), stainless steel (SS), glass coated with a conductive polymer (PANI), and carbon paper (CP). Although biofilm growth rates were generally comparable on all materials tested, the amplitude of the photo response and achievable maximum power outputs were significantly different. ITO and SS demonstrated the largest photo responses, whereas CP showed the lowest power outputs under both light and dark conditions. Furthermore, differences in the ratios of light : dark power outputs indicated that the electrochemical interactions between photosynthetic microbes and the anode may differ under light and dark conditions depending on the anodic material used. Comparisons between BPV performances and material characteristics revealed that surface roughness and surface energy, particularly the ratio of non-polar to polar interactions (the CQ ratio), may be more important than available surface area in determining biocompatibility and maximum power outputs in microbial electrochemical systems. Notably, CP was readily outperformed by all

  3. [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.

  4. Beta-range cortical motor spectral power and corticomuscular coherence as a mechanism for effective corticospinal interaction during steady-state motor output.

    PubMed

    Kristeva, Rumyana; Patino, Luis; Omlor, Wolfgang

    2007-07-01

    The steady-state motor output, occurring during static force, is characterized by synchronization between oscillatory cortical motor and muscle activity confined to the beta frequency range (15-30 Hz). The functional significance of this beta-range coherence remains unclear. We hypothesized that if the beta-range coherence had a functional role, it would have a behavioral correlate; specifically, it would be related to the precision of the steady-state motor output. To test this hypothesis, we investigated the corticomuscular (EEG-EMG) coherence in eight healthy subjects during steady-state motor output in a visuomotor task, in which the subjects exerted a static force with their right index finger to keep a visual cursor within a target zone. We show that the beta-range EEG-EMG coherence is related to the behavioral performance, i.e. the error signal between target and exerted force. Furthermore, we show that the amplitude of the cortical spectral power is also related to the performance. Moreover, we provide evidence that the EEG-EMG coherence and the cortical spectral power are not completely independent phenomena. Together, our findings indicate that higher beta-range cortical spectral power and increased corticospinal coherence in the beta-range improve motor performance during steady-state motor output. This suggests that the beta-range cortical motor spectral power and corticomuscular coherence may promote effective corticospinal interaction.

  5. Bipartite output consensus in networked multi-agent systems of high-order power integrators with signed digraph and input noises

    NASA Astrophysics Data System (ADS)

    Ma, Hongwen; Liu, Derong; Wang, Ding; Luo, Biao

    2016-10-01

    In this paper, we concentrate on investigating bipartite output consensus in networked multi-agent systems of high-order power integrators. Systems with power integrator are ubiquitous among weakly coupled, unstable and underactuated mechanical systems. In the presence of input noises, an adaptive disturbance compensator and a technique of adding power integrator are introduced to the complex nonlinear multi-agent systems to reduce the deterioration of system performance. Additionally, due to the existence of negative communication weights among agents, whether bipartite output consensus of high-order power integrators can be achieved remains unknown. Therefore, it is of great importance to study this issue. The underlying idea of designing the distributed controller is to combine the output information of each agent itself and its neighbours, the state feedback within its internal system and input adaptive noise compensator all together. When the signed digraph is structurally balanced, bipartite output consensus can be reached. Finally, numerical simulations are provided to verify the validity of the developed criteria.

  6. Between-Match Variability of Peak Power Output and Creatine Kinase Responses to Soccer Match-Play.

    PubMed

    Russell, Mark; Northeast, Jonny; Atkinson, Greg; Shearer, David A; Sparkes, William; Cook, Christian J; Kilduff, Liam P

    2015-08-01

    Post-match assessments of peak power output (PPO) during countermovement jumps and creatine kinase (CK) concentrations are common markers of recovery status in soccer players. Yet, the impact of soccer match-play on recovery in the 48 hours after competition is unclear, and the between-match variability of these responses has not been examined. Fourteen reserve team players from an English Premier League club were examined over 1-4 matches per player. Creatine kinase and PPO were measured before, 24, and 48 hours after each match. Data were analyzed with within-subjects linear mixed models. Compared with the prematch baseline, PPO was 237 ± 170 W and 98 ± 168 W lower at 24 and 48 hours, respectively (p ≤ 0.005) and CK was elevated (24 hours: 334.8 ± 107.2 μ·L(-1), 48 hours: 156.9 ± 121.0 μ·L(-1); both p ≤ 0.001) after match-play. These responses were consistent across the different matches and playing positions (p > 0.05). Within-subject correlations between PPO and CK were significant (r = -0.558; p ≤ 0.005). The between-match variability of PPO was 10.9, 11.0, and 9.9%, respectively at baseline, 24 and 48 hours, whereas for CK, the variability was 41.7, 30.0, and 34.3%, respectively. These findings highlight that more than 48 hours are needed to restore metabolic and performance perturbations after soccer match-play, and that CK demonstrates greater between-match variability than PPO. Such information is likely to be of interest to those responsible for the design of training schedules in the days after a match and sports scientists whose responsibilities include the monitoring of recovery status in soccer players.

  7. Relationships between match activities and peak power output and Creatine Kinase responses to professional reserve team soccer match-play.

    PubMed

    Russell, M; Sparkes, W; Northeast, J; Cook, C J; Bracken, R M; Kilduff, L P

    2016-02-01

    The specific movement demands of soccer that are linked to post-match recovery and readiness to train are unclear. Therefore, we examined the relationship between Global Positioning System (GPS) variables and the change (Δ; from baseline) in Creatine Kinase (CK) concentrations and peak power output (PPO; during the countermovement jump) at 24h and 48h post-match. Fifteen English Premier League reserve team players were examined over 1-4 matches. Measurements of CK and PPO were taken before (24h prior to match-play) and after (+24h and +48h) each game during which movement demands were quantified using 10Hz GPS data. High intensity distance covered (r=0.386, p=0.029; r=-0.349; p=0.050), high intensity distance covered⋅min(-1) (r=0.365, p=0.040; r=-0.364, p=0.040), high speed running distance (r=0.363, p=0.041; r=-0.360, p=0.043) and the number of sprints⋅min(-1) (r=0.410, p=0.020; r=-0.368, p=0.038) were significantly related to ΔCK and ΔPPO at +24h post-match, respectively. No relationships were observed between any match variables and ΔCK and ΔPPO after +48h of recovery. These findings highlight that high intensity match activities are related to ΔCK and ΔPPO in the 24h, but not 48h, following soccer match-play. Such information is likely of interest to those responsible for the design of soccer player's training schedules in the days following a match. PMID:26615476

  8. Generation of more than 40  W of average output power from a passively Q-switched Yb-doped fiber laser.

    PubMed

    Chakravarty, Usha; Kuruvilla, Antony; Singh, Ravindra; Upadhyaya, B N; Bindra, K S; Oak, S M

    2016-01-10

    We report on the generation of 41.6 W of average output power from a passively Q-switched ytterbium-doped fiber laser using Cr4+:YAG crystal as a saturable absorber (SA). This is the highest average power from passively Q-switched fiber lasers reported so far in the literature, to our knowledge, and it has been achieved by using a specially designed T-type double-end pumping configuration. Variation in average output power, pulse energy, pulse duration, pulse frequency, and pulse-to-pulse stability has also been studied using SAs of different linear transmissions. The effect of an intracavity SA on self-pulsing dynamics was also investigated and it was observed that, at lower input pump power near threshold, the presence of an SA enhances the peak power of relaxation oscillations to trigger the generation of stimulated Raman scattering in the gain fiber. With an increase in pump power, when the passive Q-switching threshold is reached, high peak power random self-pulses regenerate into low amplitude regular Q-switched pulses. The effect of the length of the gain medium on dual-wavelength generation at very low input pump power and broadband generation at sufficiently higher pump power has also been explored. PMID:26835764

  9. Comparison of power output by rice (Oryza sativa) and an associated weed (Echinochloa glabrescens) in vascular plant bio-photovoltaic (VP-BPV) systems.

    PubMed

    Bombelli, Paolo; Iyer, Durgaprasad Madras Rajaraman; Covshoff, Sarah; McCormick, Alistair J; Yunus, Kamran; Hibberd, Julian M; Fisher, Adrian C; Howe, Christopher J

    2013-01-01

    Vascular plant bio-photovoltaics (VP-BPV) is a recently developed technology that uses higher plants to harvest solar energy and the metabolic activity of heterotrophic microorganisms in the plant rhizosphere to generate electrical power. In the present study, electrical output and maximum power output variations were investigated in a novel VP-BPV configuration using the crop plant rice (Oryza sativa L.) or an associated weed, Echinochloa glabrescens (Munro ex Hook. f.). In order to compare directly the physiological performances of these two species in VP-BPV systems, plants were grown in the same soil and glasshouse conditions, while the bio-electrochemical systems were operated in the absence of additional energy inputs (e.g. bias potential, injection of organic substrate and/or bacterial pre-inoculum). Diurnal oscillations were clearly observed in the electrical outputs of VP-BPV systems containing the two species over an 8-day growth period. During this 8-day period, O. sativa generated charge ∼6 times faster than E. glabrescens. This greater electrogenic activity generated a total charge accumulation of 6.75 ± 0.87 Coulombs for O. sativa compared to 1.12 ± 0.16 for E. glabrescens. The average power output observed over a period of about 30 days for O. sativa was significantly higher (0.980 ± 0.059 GJ ha(-1) year(-1)) than for E. glabrescens (0.088 ± 0.008 GJ ha(-1) year(-1)). This work indicates that electrical power can be generated in both VP-BPV systems (O. sativa and E. glabrescens) when bacterial populations are self-forming. Possible reasons for the differences in power outputs between the two plant species are discussed.

  10. Temporal Aspects of the V[o.sub.2] Response at the Power Output Associated with V[o.sub.2]peak in Well Trained Cyclists-Implications for Interval Training Prescription

    ERIC Educational Resources Information Center

    Laursen, Paul B.; Shing, Cecilia M.; Jenkins, David G.

    2004-01-01

    The power output achieved at peak oxygen consumption (V[O.sub.2]peak) and the time this power can be maintained (i.e., Tmax) have been used in prescribing high-intensity interval training. In this context, the present study examined temporal aspects of the V[O.sub.2] response to exercise at the cycling power that output well trained cyclists…

  11. Experimental demonstration of acoustic wave induced magnetization switching in dipole coupled magnetostrictive nanomagnets for ultralow power computing

    NASA Astrophysics Data System (ADS)

    Sampath, Vimal; D'Souza, Noel; Atkinson, Gary M.; Bandyopadhyay, Supriyo; Atulasimha, Jayasimha

    2016-09-01

    Dipole-coupled cobalt nanomagnet pairs of elliptical shape (with their major axes parallel) are delineated on 128° Y-cut lithium niobate. Each pair is initially magnetized along the major axis with a magnetic field forming the (↑↑) state. When an acoustic wave (AW) is launched in the substrate from interdigitated electrodes, the softer nanomagnet in the pair flips to produce the (↑↓) state since the AW modulates the stress anisotropy. This executes the logical NOT operation because the output bit encoded in the magnetization state of the softer nanomagnet becomes the logic complement of the input bit encoded in the magnetization of the harder one. The AW acts as a clock to trigger the NOT operation and the energy dissipated is a few tens of aJ. Such AW clocking can be utilized to flip nanomagnets in a chain sequentially to steer logic bits unidirectionally along a nanomagnetic logic wire with miniscule energy dissipation.

  12. COOH-terminal truncation of flightin decreases myofilament lattice organization, cross-bridge binding, and power output in Drosophila indirect flight muscle.

    PubMed

    Tanner, Bertrand C W; Miller, Mark S; Miller, Becky M; Lekkas, Panagiotis; Irving, Thomas C; Maughan, David W; Vigoreaux, Jim O

    2011-08-01

    The indirect flight muscle (IFM) of insects is characterized by a near crystalline myofilament lattice structure that likely evolved to achieve high power output. In Drosophila IFM, the myosin rod binding protein flightin plays a crucial role in thick filament organization and sarcomere integrity. Here we investigate the extent to which the COOH terminus of flightin contributes to IFM structure and mechanical performance using transgenic Drosophila expressing a truncated flightin lacking the 44 COOH-terminal amino acids (fln(ΔC44)). Electron microscopy and X-ray diffraction measurements show decreased myofilament lattice order in the fln(ΔC44) line compared with control, a transgenic flightin-null rescued line (fln(+)). fln(ΔC44) fibers produced roughly 1/3 the oscillatory work and power of fln(+), with reduced frequencies of maximum work (123 Hz vs. 154 Hz) and power (139 Hz vs. 187 Hz) output, indicating slower myosin cycling kinetics. These reductions in work and power stem from a slower rate of cross-bridge recruitment and decreased cross-bridge binding in fln(ΔC44) fibers, although the mean duration of cross-bridge attachment was not different between both lines. The decreases in lattice order and myosin kinetics resulted in fln(ΔC44) flies being unable to beat their wings. These results indicate that the COOH terminus of flightin is necessary for normal myofilament lattice organization, thereby facilitating the cross-bridge binding required to achieve high power output for flight.

  13. Type-II vertical-external-cavity surface-emitting laser with Watt level output powers at 1.2 μm

    NASA Astrophysics Data System (ADS)

    Möller, C.; Fuchs, C.; Berger, C.; Ruiz Perez, A.; Koch, M.; Hader, J.; Moloney, J. V.; Koch, S. W.; Stolz, W.

    2016-02-01

    Semiconductor laser characteristics based on type-II band-aligned quantum well heterostructures for the emission at 1.2 μm are presented. Ten "W"-quantum wells consisting of GaAs/(GaIn)As/Ga(AsSb)/(GaIn)As/GaAs are arranged as resonant periodic gain in a vertical-external-cavity surface-emitting laser. Its structure is analyzed by X-ray diffraction, photoluminescence, and reflectance measurements. The laser's power curves and spectra are investigated. Output powers at Watt level are achieved, with a maximum output power of 4 W. It is confirmed that laser operation only involves the type-II transition. A blue shift of the material gain is observed while the modal gain exhibits a red shift.

  14. Introduction to acoustic emission

    NASA Technical Reports Server (NTRS)

    Possa, G.

    1983-01-01

    Typical acoustic emission signal characteristics are described and techniques which localize the signal source by processing the acoustic delay data from multiple sensors are discussed. The instrumentation, which includes sensors, amplifiers, pulse counters, a minicomputer and output devices is examined. Applications are reviewed.

  15. Perception of power modulation of light in conjunction with acoustic stimulation

    NASA Astrophysics Data System (ADS)

    Hahlweg, Cornelius F.; Weyer, Cornelia; Gercke-Hahn, Harald; Gutzmann, Holger L.; Brahmann, Andre; Rothe, Hendrik

    2013-09-01

    The present paper is derived from an ongoing study on the human perception of combined optical and acoustical periodical stimuli. Originating from problems of occupational medicine concerning artificial illumination and certain machinery with coherent optical and acoustical emissions there are effects which are interesting in the context of Optics and Music. Because of the difficulties in evaluation of physical and psychological effects of such coherent stimuli in a first step we questioned if such coherence is perceivable at all. Concept, experimental set-up and first results are discussed in short.

  16. A high-powered siren for stable acoustic levitation of dense materials in the earth's gravity

    NASA Technical Reports Server (NTRS)

    Gammel, Paul M.; Croonquist, Arvid P.; Wang, Taylor G.

    1988-01-01

    Levitation of large dense samples (e.g., 1-cm diameter steel balls) has been performed in a 1-g environment. A siren was used to study the effects of reflector geometry and variable-frequency operation in order to attain stable acoustic positioning. The harmonic content and spatial distribution of the acoustic field have been investigated. The best stability was obtained with an open reflector system, using a flat lower reflector and a slightly concave upper reflector while operating at a frequency slightly below resonance.

  17. Design and Modeling of High Power Density Acoustic Transducer Materials for Autonomous Undersea Vehicles

    NASA Astrophysics Data System (ADS)

    Heitmann, Adam Arthur

    Advances in piezocrystal transducer materials technology has opened new avenues to impact the size, weight, and power consumption of sonar systems for deployment in autonomous undersea vehicles (AUVs). Although piezocrystals exhibit exceptional electromechanical properties, they have low ferroelectric Curie temperatures, small electrical coercivities, and exhibit temperature, electrical field, and/or stress induced phase transitions between ferroelectric phases with differing electromechanical properties. New piezocrystal materials are required that can provide the compositional tailoring capability needed to increase the Curie temperature and coercive field, ameliorate the deleterious effects of ferroelectric-ferroelectric phase transitions, and enable property optimization for specific transducer applications. Currently, new piezocrystal systems and compositions are selected almost exclusively by empirical 'make and measure' approaches guided by past experiences. These empirical processes can be time and labor intensive and as a result there exists only limited predictive capability for finding new piezocrystal compositions even in known piezocrystal systems. In this study we seek to develop a comprehensive phenomenological theory and a unified parameterization scheme applicable to binary and ternary ferroelectric solid solution systems in order to enable the accelerated development and characterization of new piezocrystal systems for optimized transducer performance. A modified form of the classical Ginzburg-Landau-Devonshire theory of weak first-order transitions is applied to perovskite-structured ferroelectric systems based on the ternary oxide compounds, barium titanate and lead titanate, which places special emphasis on the role played by the crystallographic anisotropy of polarization. It is shown that the theory produces excellent qualitative agreement with the experimentally measured phase diagram topologies, crystal lattice parameters, and

  18. Single-mode monolithic fiber laser with 200  W output power at a wavelength of 1018  nm.

    PubMed

    Ottenhues, Christoph; Theeg, Thomas; Hausmann, Katharina; Wysmolek, Mateusz; Sayinc, Hakan; Neumann, Jörg; Kracht, Dietmar

    2015-11-01

    We report on an ytterbium-doped monolithic fiber laser at a wavelength of 1018 nm with an output power of 200 W in continuous wave operation. The optimal parameters for setting up such a high-power fiber laser with an ytterbium-doped fiber are investigated and discussed in detail. An in-house-developed pump light stripper and a single-mode fused fiber coupler were applied to use the fiber laser for core-pumping of ytterbium-doped high-power fiber amplifiers in a monolithic setup. PMID:26512466

  19. Estimation of broadband acoustic power due to rib forces on a reinforced panel under turbulent boundary layer-like pressure excitation. II. Applicability and validation.

    PubMed

    Rumerman, M L

    2001-02-01

    The previous paper showed that, when the attachment forces on a rib-reinforced panel subjected to turbulent boundary layer excitation can be considered to radiate independently, the rib-related acoustic power in a broad (e.g., one-third octave) frequency band can be estimated as the product of the average mean squared force, the real part of the radiation admittance of an attachment force, and the number of ribs. This paper shows that the radiation condition is always approximated when the acoustic wavelength is less than twice the rib spacing of a periodically reinforced panel, and generally applies at lower frequencies where the acoustic wavelength is less than four times the rib spacing. The procedure is used to estimate the broadband acoustic power radiated per rib of an infinite periodically reinforced membrane and plate in water, and the results are shown to agree with those of "exact" calculations.

  20. Active drag, useful mechanical power output and hydrodynamic force coefficient in different swimming strokes at maximal velocity.

    PubMed

    Kolmogorov, S V; Duplishcheva, O A

    1992-03-01

    By comparing the time of the same distance swum with and without an added resistance, under the assumption of an equal power output in both cases, the drag of 73 top swimmers was estimated. The active drag Fr(a.d.) at maximal swimming velocities varied considerably across strokes and individuals. In the females Fr(a.d.) ranged from 69.78 to 31.16 N in the front-crawl, from 83.04 to 37.78 N in dolphin, from 93.56 to 45.19 N in breaststroke, and from 65.51 to 37.79 N in back-stroke. In the males Fr(a.d.) ranged from 167.11 to 42.23 N in front-crawl, from 156.09 to 46.95 N in dolphin, from 176.87 to 55.61 N in breaststroke, and from 146.28 to 46.36 N in back-stroke. Also, the ratio of Fr(a.d.) to the passive drag Fr(a.d.) as determined for the analogical velocity in a tugging condition (in standard body position-front gliding) shows considerable individual variations. In the female swimmers variations in Fr(a.d.)/Fr(p.d.) ranged from 145.17 to 59.94% in front-crawl, from 192.39 to 85.57% in dolphin, from 298.03 to 124.50% in breaststroke, and from 162.87 to 85.61% in back-stroke. In the male swimmers variations in Fr(a.d.)/Fr(p.d.) ranged from 162.24 to 62.39% in front-crawl, from 191.70 to 70.38% in dolphin, from 295.57 to 102.83% in breaststroke, and from 198.82 to 74.48% in back-stroke. The main reason for such variations is found in the individual features of swimming technique and can be quantitatively estimated with the hydrodynamic force coefficient, which thus provides an adequate index of technique. PMID:1564064

  1. Effects of low and high cadence interval training on power output in flat and uphill cycling time-trials.

    PubMed

    Nimmerichter, Alfred; Eston, Roger; Bachl, Norbert; Williams, Craig

    2012-01-01

    This study tested the effects of low-cadence (60 rev min(-1)) uphill (Int(60)) or high-cadence (100 rev min(-1)) level-ground (Int(100)) interval training on power output (PO) during 20-min uphill (TT(up)) and flat (TT(flat)) time-trials. Eighteen male cyclists ([Formula: see text]: 58.6 ± 5.4 mL min(-1) kg(-1)) were randomly assigned to Int(60), Int(100) or a control group (Con). The interval training comprised two training sessions per week over 4 weeks, which consisted of six bouts of 5 min at the PO corresponding to the respiratory compensation point (RCP). For the control group, no interval training was conducted. A two-factor ANOVA revealed significant increases on performance measures obtained from a laboratory-graded exercise test (GXT) (P (max): 2.8 ± 3.0%; p < 0.01; PO and [Formula: see text] at RCP: 3.6 ± 6.3% and 4.7 ± 8.2%, respectively; p < 0.05; and [Formula: see text] at ventilatory threshold: 4.9 ± 5.6%; p < 0.01), with no significant group effects. Significant interactions between group and uphill and flat time-trial, pre- versus post-training on PO were observed (p < 0.05). Int(60) increased PO during both TT(up) (4.4 ± 5.3%) and TT(flat) (1.5 ± 4.5%). The changes were -1.3 ± 3.6, 2.6 ± 6.0% for Int(100) and 4.0 ± 4.6%, -3.5 ± 5.4% for Con during TT(up) and TT(flat), respectively. PO was significantly higher during TT(up) than TT(flat) (4.4 ± 6.0; 6.3 ± 5.6%; pre and post-training, respectively; p < 0.001). These findings suggest that higher forces during the low-cadence intervals are potentially beneficial to improve performance. In contrast to the GXT, the time-trials are ecologically valid to detect specific performance adaptations.

  2. A supervisor for the successive 3D computations of magnetic, mechanical and acoustic quantities in power oil inductors and transformers

    SciTech Connect

    Reyne, G.; Magnin, H.; Berliat, G.; Clerc, C.

    1994-09-01

    A supervisor has been developed so as to allow successive 3D computations of different quantities by different softwares on the same physical problem. Noise of a given power oil transformer can be deduced from the surface vibrations of the tank. These vibrations are obtained through a mechanic computation whose Inputs are the electromagnetic forces provided . by an electromagnetic computation. Magnetic, mechanic and acoustic experimental data are compared with the results of the 3D computations. Stress Is put on the main characteristics of the supervisor such as the transfer of a given quantity from one mesh to the other.

  3. Investigation of a stall deterrent system utilizing an acoustic stall sensor

    NASA Technical Reports Server (NTRS)

    Bennett, A. G.; Owens, J. K.; Harris, R. L.

    1977-01-01

    A simple rugged acoustic stall sensor which has an output proportional to angle of attack near wing stall has been evaluated on a Cessna 319 aircraft. A sensor position has been found on the wing where the sensor output is only slightly affected by engine power level, yaw angle, flap position and wing roughness. The NASA LRC General Aviation Simulator has been used to evaluate the acoustic sensor output as a control signal for active stall deterrent systems. It has been found that a simple control algorithm is sufficient for stall deterrence.

  4. Biomolecule-adsorption-dependent piezoelectric output of ZnO nanowire nanogenerator and its application as self-powered active biosensor.

    PubMed

    Zhao, Yayu; Deng, Ping; Nie, Yuxin; Wang, Penglei; Zhang, Yan; Xing, Lili; Xue, Xinyu

    2014-07-15

    Self-powered active biosensor has been realized from ZnO nanowire (NW) nanogenerator (NG). The piezoelectric output generated by ZnO NW NG can act not only as a power source for driving the device, but also as a biosensing signal. After immersing in 10(-3) g ml(-1) human immunoglobulin G (IgG), the piezoelectric output voltage of the device under compressive deformation decreases from 0.203±0.0176 V (without IgG) to 0.038±0.0035 V. Such a self-powered biosensor has higher response than transistor-type biosensor (I-V behavior). The response of self-powered biosensor is in a linear relationship with IgG concentration (logarithm, 10(-7)-10(-3) g ml(-1)) and the limit of detection (LOD) on IgG of the device is about 6.9 ng ml(-1). The adsorption of biomolecules on the surface of ZnO NWs can modify the free-carrier density, which vary the screening effect of free-carriers on the piezoelectric output. The present results demonstrate a feasible approach for actively detecting biomolecules by coupling the piezotronic and biosensing characteristics of ZnO NWs.

  5. Design and implementation of an omni-directional underwater acoustic micro-modem based on a low-power micro-controller unit.

    PubMed

    Won, Tae-Hee; Park, Sung-Joon

    2012-01-01

    For decades, underwater acoustic communication has been restricted to the point-to-point long distance applications such as deep sea probes and offshore oil fields. For this reason, previous acoustic modems were typically characterized by high data rates and long working ranges at the expense of large size and high power consumption. Recently, as the need for underwater wireless sensor networks (UWSNs) has increased, the research and development of compact and low-power consuming communication devices has become the focus. From the consideration that the requisites of acoustic modems for UWSNs are low power consumption, omni-directional beam pattern, low cost and so on, in this paper, we design and implement an omni-directional underwater acoustic micro-modem satisfying these requirements. In order to execute fast digital domain signal processing and support flexible interfaces with other peripherals, an ARM Cortex-M3 is embedded in the micro-modem. Also, for the realization of small and omni-directional properties, a spherical transducer having a resonant frequency of 70 kHz and a diameter of 34 mm is utilized for the implementation. Physical layer frame format and symbol structure for efficient packet-based underwater communication systems are also investigated. The developed acoustic micro-modem is verified analytically and experimentally in indoor and outdoor environments in terms of functionality and performance. Since the modem satisfies the requirements for use in UWSNs, it could be deployed in a wide range of applications requiring underwater acoustic communication. PMID:22438765

  6. Design and implementation of an omni-directional underwater acoustic micro-modem based on a low-power micro-controller unit.

    PubMed

    Won, Tae-Hee; Park, Sung-Joon

    2012-01-01

    For decades, underwater acoustic communication has been restricted to the point-to-point long distance applications such as deep sea probes and offshore oil fields. For this reason, previous acoustic modems were typically characterized by high data rates and long working ranges at the expense of large size and high power consumption. Recently, as the need for underwater wireless sensor networks (UWSNs) has increased, the research and development of compact and low-power consuming communication devices has become the focus. From the consideration that the requisites of acoustic modems for UWSNs are low power consumption, omni-directional beam pattern, low cost and so on, in this paper, we design and implement an omni-directional underwater acoustic micro-modem satisfying these requirements. In order to execute fast digital domain signal processing and support flexible interfaces with other peripherals, an ARM Cortex-M3 is embedded in the micro-modem. Also, for the realization of small and omni-directional properties, a spherical transducer having a resonant frequency of 70 kHz and a diameter of 34 mm is utilized for the implementation. Physical layer frame format and symbol structure for efficient packet-based underwater communication systems are also investigated. The developed acoustic micro-modem is verified analytically and experimentally in indoor and outdoor environments in terms of functionality and performance. Since the modem satisfies the requirements for use in UWSNs, it could be deployed in a wide range of applications requiring underwater acoustic communication.

  7. Input and output budgets of radiocesium concerning the forest floor in the mountain forest of Fukushima released from the TEPCO's Fukushima Dai-ichi nuclear power plant accident.

    PubMed

    Niizato, Tadafumi; Abe, Hironobu; Mitachi, Katsuaki; Sasaki, Yoshito; Ishii, Yasuo; Watanabe, Takayoshi

    2016-09-01

    Estimations of radiocesium input and output concerning the forest floor within a mountain forest region have been conducted in the north and central part of the Abukuma Mountains of Fukushima, northeast Japan, after a 2-3 year period following the TEPCO Fukushima Dai-ichi nuclear power plant accident. The radiocesium input and output associated with surface washoff, throughfall, stemflow, and litterfall processes at experimental plots installed on the forest floor of evergreen Japanese cedars and deciduous Konara oaks have been monitored. Despite the high output potential in the mountainous forest of Fukushima, the results at both monitoring locations show the radiocesium input to be 4-50 times higher than the output during the summer monsoon in Fukushima. These results indicate that the radiocesium tends to be preserved in the forest ecosystem due to extremely low output ratios (0.05%-0.19%). Thus, the associated fluxes throughout the circulation process are key issues for the projecting the environmental fate of the radiocesium levels, along with the subsequent reconstruction of life emphasized within the setting.

  8. Input and output budgets of radiocesium concerning the forest floor in the mountain forest of Fukushima released from the TEPCO's Fukushima Dai-ichi nuclear power plant accident.

    PubMed

    Niizato, Tadafumi; Abe, Hironobu; Mitachi, Katsuaki; Sasaki, Yoshito; Ishii, Yasuo; Watanabe, Takayoshi

    2016-09-01

    Estimations of radiocesium input and output concerning the forest floor within a mountain forest region have been conducted in the north and central part of the Abukuma Mountains of Fukushima, northeast Japan, after a 2-3 year period following the TEPCO Fukushima Dai-ichi nuclear power plant accident. The radiocesium input and output associated with surface washoff, throughfall, stemflow, and litterfall processes at experimental plots installed on the forest floor of evergreen Japanese cedars and deciduous Konara oaks have been monitored. Despite the high output potential in the mountainous forest of Fukushima, the results at both monitoring locations show the radiocesium input to be 4-50 times higher than the output during the summer monsoon in Fukushima. These results indicate that the radiocesium tends to be preserved in the forest ecosystem due to extremely low output ratios (0.05%-0.19%). Thus, the associated fluxes throughout the circulation process are key issues for the projecting the environmental fate of the radiocesium levels, along with the subsequent reconstruction of life emphasized within the setting. PMID:27131868

  9. Input and Output Compensation for the Cochlear Traveling Wave Delay in Wide-Band ABR Recordings: Implications for Small Acoustic Tumor Detection

    PubMed Central

    Don, Manuel; Elberling, Claus; Malof, Erin

    2011-01-01

    Background The Stacked ABR (auditory brainstem response) attempts at the output of the auditory periphery to compensate for the temporal dispersion of neural activation caused by the cochlear traveling wave in response to click stimulation. Compensation can also be made at the input by using a chirp stimulus. It has been demonstrated that the Stacked ABR is sensitive to small tumors that are often missed by standard ABR latency measures. Purpose Because a chirp stimulus requires only a single data acquisition run whereas the Stacked ABR requires six, we try to evaluate some indirect evidence justifying the use of a chirp for small tumor detection. Research Design We compared the sensitivity and specificity of different Stacked ABRs formed by aligning the derived-band ABRs according to (1) the individual’s peak latencies, (2) the group mean latencies, and (3) the modeled latencies used to develop a chirp. Results For tumor detection with a chosen sensitivity of 95%, a relatively high specificity of 85% may be achieved with a chirp. Conclusion It appears worthwhile to explore the actual use of a chirp because significantly shorter test and analysis times might be possible. PMID:19927673

  10. Unveiling acoustic physics of the CMB using nonparametric estimation of the temperature angular power spectrum for Planck

    SciTech Connect

    Aghamousa, Amir; Shafieloo, Arman; Arjunwadkar, Mihir; Souradeep, Tarun E-mail: shafieloo@kasi.re.kr E-mail: tarun@iucaa.ernet.in

    2015-02-01

    Estimation of the angular power spectrum is one of the important steps in Cosmic Microwave Background (CMB) data analysis. Here, we present a nonparametric estimate of the temperature angular power spectrum for the Planck 2013 CMB data. The method implemented in this work is model-independent, and allows the data, rather than the model, to dictate the fit. Since one of the main targets of our analysis is to test the consistency of the ΛCDM model with Planck 2013 data, we use the nuisance parameters associated with the best-fit ΛCDM angular power spectrum to remove foreground contributions from the data at multipoles ℓ ≥50. We thus obtain a combined angular power spectrum data set together with the full covariance matrix, appropriately weighted over frequency channels. Our subsequent nonparametric analysis resolves six peaks (and five dips) up to ℓ ∼1850 in the temperature angular power spectrum. We present uncertainties in the peak/dip locations and heights at the 95% confidence level. We further show how these reflect the harmonicity of acoustic peaks, and can be used for acoustic scale estimation. Based on this nonparametric formalism, we found the best-fit ΛCDM model to be at 36% confidence distance from the center of the nonparametric confidence set—this is considerably larger than the confidence distance (9%) derived earlier from a similar analysis of the WMAP 7-year data. Another interesting result of our analysis is that at low multipoles, the Planck data do not suggest any upturn, contrary to the expectation based on the integrated Sachs-Wolfe contribution in the best-fit ΛCDM cosmology.

  11. The effect of the size of the opening on the acoustic power radiated by a reed woodwind instrument

    NASA Astrophysics Data System (ADS)

    Guilloteau, Alexis; Guillemain, Philippe; Kergomard, Jean; Jousserand, Michael

    2015-05-01

    For a given note, the maker of woodwind instruments can choose between different sizes for the toneholes under the condition that the location is appropriate. The present paper aims at analyzing the consequences of this choice on the power radiated by a hole, which depends on the coupling between the acoustic resonator and the excitation mechanism of the self-sustained oscillation, thus on the blowing pressure. For that purpose a simplified reed instrument is investigated, with a cylindrical pipe and a unique orifice at the pipe termination. The orifice diameter was varied between the pipe diameter and a size such that the instrument did not play. The pipe length was in each case adjusted to keep the resonance frequency constant. A simple analytical model predicts that, for a given mouth pressure of the instrumentalist, the radiated power does not depend on the size of the hole if it is wide enough and if resonator losses are ignored. Numerical solution of a model including losses confirms this result: the difference in radiated power between two diaphragm sizes remains smaller than the difference obtained if the radiated power would be proportional to the orifice cross section area. This is confirmed by experiments using an artificial mouth, but the results show that the linear losses are underestimated, and that significant nonlinear losses occur. The measurements are limited to the acoustic pressure at a given distance of the orifice. Experiments also show that rounding edges of the orifice reduces nonlinear losses resulting in an increase of the power radiated and of the extinction threshold, and resulting in a larger dynamical range.

  12. All-solid-state continuous-wave frequency-doubled Nd:YAG-BiBO laser with 2.8-W output power at 473 nm.

    PubMed

    Czeranowsky, C; Heumann, E; Huber, G

    2003-03-15

    We report on a diode-pumped Nd:YAG laser with 4.6 W of linear polarized continuous-wave (cw) output power on the 4F3/2 --> 4I9/2 transitions at 946 nm. Three different crystals, cut for critical type I phase matching at room temperature, are used for the intracavity frequency doubling of the laser: 10-mm-long LiBaO5 (LBO), an 8-mm-long beta-BaB2O4 (BBO), and a 10.4-mm-long BiB3O6 (BiBO) grown by FEE GmbH. Up to 2.8 W of cw output power in the blue spectral range at 473 nm has been achieved with the BiBO crystal (2.1 W with BBO and 1.5 W with LBO).

  13. Generalized formula for continuous-wave end-pumped Yb-doped material amplifier gain and laser output power in various pumping configurations.

    PubMed

    Bourdet, Gilbert L; Bartnicki, Eric

    2006-12-20

    We present a general formula fitted for computing the amplification and laser output power in a Yb-doped material under various quasi-end-pumping configurations. These configurations include single pass pumping, backreflection pumping in which the pump is reflected by a mirror set on the rear face of the amplifier medium, contrapropagation pumping where two pump beams are launched on both sides of the amplifier and, for every configuration, regenerative pumping in which the transmitted or reflected pump beam is recycled using the proper apparatus. We show that, with regenerative pumping, the efficiency is drastically improved and the optimum amplifier length leading to the maximum laser output power is shorter compared with the one obtained with conventional pumping. In this model, we do not take temperature effect into account. PMID:17151761

  14. Intrinsic spontaneous emission-induced fluctuations of the output optical beam power and phase in a diode amplifier

    NASA Astrophysics Data System (ADS)

    Bogatov, A. P.; Drakin, A. E.; D'yachkov, N. V.; Gushchik, T. I.

    2016-08-01

    Output optical beam intensity and phase fluctuations are analysed in a classical approach to describing the propagation and amplification of spontaneous emission in the active region of a laser diode with a gain saturated by input monochromatic light. We find their spectral densities and dispersion and the correlation coefficient of the two-dimensional probability distribution function of the fluctuations.

  15. Phosphate ytterbium-doped single-mode all-solid photonic crystal fiber with output power of 13.8 W.

    PubMed

    Wang, Longfei; He, Dongbing; Feng, Suya; Yu, Chunlei; Hu, Lili; Qiu, Jianrong; Chen, Danping

    2015-01-01

    Single-mode ytterbium-doped phosphate all-solid photonic crystal fiber (AS-PCF) with 13.8 W output power and 32% slope efficiency was reported. By altering the diameter of the rods around the doped core and thus breaking the symmetry of the fiber, a polarization-maintaining AS-PCF with degree of polarization of >85% was also achieved, for the first time to knowledge, in a phosphate PCF.

  16. Phosphate ytterbium-doped single-mode all-solid photonic crystal fiber with output power of 13.8 W

    PubMed Central

    Wang, Longfei; He, Dongbing; Feng, Suya; Yu, Chunlei; Hu, Lili; Qiu, Jianrong; Chen, Danping

    2015-01-01

    Single-mode ytterbium-doped phosphate all-solid photonic crystal fiber (AS-PCF) with 13.8 W output power and 32% slope efficiency was reported. By altering the diameter of the rods around the doped core and thus breaking the symmetry of the fiber, a polarization-maintaining AS-PCF with degree of polarization of >85% was also achieved, for the first time to knowledge, in a phosphate PCF. PMID:25684731

  17. Splitting a droplet with oil encapsulation using surface acoustic wave excited by electric signal with low power

    NASA Astrophysics Data System (ADS)

    Zhang, Anliang; Zha, Yan; Fu, Xingting

    2013-07-01

    A new method for splitting a droplet with oil encapsulation is presented. An interdigital transducer and a reflector are fabricated on a 128° yx-LiNbO3 piezoelectric substrate using microelectric technology. An electric signal with the power of 12.3 dBm is applied to the interdigital transducer to generate surface acoustic wave, which is radiated into a droplet with oil encapsulation, leading to surface acoustic wave streaming force. When the electric signal is suddenly moved off, the breakup of the droplet occurs due to inertial force. Color dye solution droplets encapsulated by oil droplets are demonstrated. The effects of electric power, the volume ratio of color dye solution to oil, and the volume of mother droplet on the breakup of droplets are studied. As applications, the presented method is successfully applied to mixture operation and color development reaction of two droplets. The method provides a new sample preparation technique, which is helpful for microfluidic biochemical analysis in a piezoelectric microfluidic system.

  18. Effects of creatine supplementation and three days of resistance training on muscle strength, power output, and neuromuscular function.

    PubMed

    Cramer, Joel T; Stout, Jeffrey R; Culbertson, Julie Y; Egan, Alison D

    2007-08-01

    Previous studies have demonstrated increases in peak torque (PT) and decreases in acceleration time (ACC) after only 2 days of resistance training, and other studies have reported improvements in isokinetic performance after 5 days of creatine supplementation. Consequently, there may be a combined benefit of creatine supplementation and short-term resistance training for eliciting rapid increases in muscle strength, which may be important for short-term rehabilitation and return-to-play for previously injured athletes. The purpose of this study, therefore, was to examine the effects of 3 days of isokinetic resistance training combined with 8 days of creatine monohydrate supplementation on PT, mean power output (MP), ACC, surface electromyography (EMG), and mechanomyography (MMG) of the vastus lateralis muscle during maximal concentric isokinetic leg extension muscle actions. Twenty-five men (mean age +/- SD = 21 +/- 3 years, stature = 177 +/- 6 cm, and body mass = 80 +/- 12 kg) volunteered to participate in this 9-day, double-blind, placebo-controlled study and were randomly assigned to either the creatine (CRE; n = 13) or placebo (PLA; n = 12) group. The CRE group ingested the treatment drink (280 kcal; 68 g carbohydrate; 10.5 g creatine), whereas the PLA group received an isocaloric placebo (70 g carbohydrate). Two servings per day (morning and afternoon) were administered in the laboratory on days 1-6, with only 1 serving on days 7-8. Before (pre; day 1) and after (post; day 9) the resistance training, maximal voluntary concentric isokinetic leg extensions at 30, 150, and 270 degrees x s(-1) were performed on a calibrated Biodex System 3 dynamometer. Three sets of 10 repetitions at 150 degrees x s(-1) were performed on days 3, 5, and 7. Peak torque increased (p = 0.005; eta(2) = 0.296), whereas ACC decreased (p < 0.001; eta(2) = 0.620), from pretraining to posttraining for both the CRE and PLA groups at each velocity (30, 150, and 270 degrees x s(-1)). Peak

  19. Acoustically driven arrayed waveguide grating.

    PubMed

    Crespo-Poveda, A; Hernández-Mínguez, A; Gargallo, B; Biermann, K; Tahraoui, A; Santos, P V; Muñoz, P; Cantarero, A; de Lima, M M

    2015-08-10

    We demonstrate compact tunable phased-array wavelength-division multiplexers driven by surface acoustic waves (SAWs) in the low GHz range. The devices comprise two couplers, which respectively split and combine the optical signal, linked by an array of single-mode waveguides (WGs). Two different layouts are presented, in which multi-mode interference couplers or free propagating regions were separately employed as couplers. The multiplexers operate on five equally distributed wavelength channels, with a spectral separation of 2 nm. A standing SAW modulates the refractive index of the arrayed WGs. Each wavelength component periodically switches paths between the output channel previously asigned by the design and the adjacent channels, at a fixed applied acoustic power. The devices were monolithically fabricated on (Al,Ga)As. A good agreement between theory and experiment is achieved.

  20. Generation of Acoustic Gravity Waves by Periodic Radio Transmissions from a High-Power Ionospheric Heater

    NASA Astrophysics Data System (ADS)

    Frolov, Vladimir; Chernogor, Leonid; Rozumenko, Victor

    The Radiophysical Research Institute (Nizhny Novgorod, Russia) and Kharkiv V. N. Karazin National University (Kharkiv, Ukraine) have studied opportunities for the effective generation of acoustic gravity waves (AGWs) in 3 - 180-min period range. The excitation of such waves was conducted for the last several years using the SURA heating facility (Nizhny Novgorod). The detection of the HF-induced AGWs was carried out in the Radiophysical Observatory located near Kharkiv City at a distance of about 960 km from the SURA. A coherent radar for vertical sounding, an ionosonde, and magnetometer chains were used in our measurements. The main results are the following (see [1-5]): 1. Infrasound oscillation trains with a period of 6 min are detected during periodic SURA heater turn-on and -off. Similar oscillation trains are detected after long time pumping, during periodic transmissions with a period of 20 s, as well as after pumping turn-off. The train recordings begin 28 - 54 min after the heater turn-on or -off, and the train propagation speeds are about 300 - 570 m/s, the value of which is close to the sound speed at upper atmospheric altitudes. The amplitude of the Doppler shift frequency is of 10 - 40 mHz, which fits to the 0.1 - 0.3% electron density disturbances at ionospheric altitudes. The amplitude of the infrasound oscillations depends on the SURA mode of operation and the state of the upper atmosphere and ionosphere. 2. High-power radio transmissions stimulate the generation (or enhancement) of waves at ionospheric altitudes in the range of internal gravity wave periods. The HF-induced waves propagate with speeds of 360 - 460 m/s and produce changes in electron density with amplitudes of 2 - 3%. The generation of such periodic perturbations is more preferable with periods of 10 - 60 minutes. Their features depend significantly on the heater mode of operation. It should be stressed that perturbation intensity increases when a pumping wave frequency approaches

  1. COOH-terminal truncation of flightin decreases myofilament lattice organization, cross-bridge binding, and power output in Drosophila indirect flight muscle

    SciTech Connect

    Tanner, Bertrand C.W.; Miller, Mark S.; Miller, Becky M.; Lekkas, Panagiotis; Irving, Thomas C.; Maughan, David W.; Vigoreaux, Jim O.

    2011-08-26

    The indirect flight muscle (IFM) of insects is characterized by a near crystalline myofilament lattice structure that likely evolved to achieve high power output. In Drosophila IFM, the myosin rod binding protein flightin plays a crucial role in thick filament organization and sarcomere integrity. Here we investigate the extent to which the COOH terminus of flightin contributes to IFM structure and mechanical performance using transgenic Drosophila expressing a truncated flightin lacking the 44 COOH-terminal amino acids (fln{sup {Delta}C44}). Electron microscopy and X-ray diffraction measurements show decreased myofilament lattice order in the fln{sup {Delta}C44} line compared with control, a transgenic flightin-null rescued line (fln{sup +}). fln{sup {Delta}C44} fibers produced roughly 1/3 the oscillatory work and power of fln{sup +}, with reduced frequencies of maximum work (123 Hz vs. 154 Hz) and power (139 Hz vs. 187 Hz) output, indicating slower myosin cycling kinetics. These reductions in work and power stem from a slower rate of cross-bridge recruitment and decreased cross-bridge binding in fln{sup {Delta}C44} fibers, although the mean duration of cross-bridge attachment was not different between both lines. The decreases in lattice order and myosin kinetics resulted in fln{sup {Delta}C44} flies being unable to beat their wings. These results indicate that the COOH terminus of flightin is necessary for normal myofilament lattice organization, thereby facilitating the cross-bridge binding required to achieve high power output for flight.

  2. Effects of Creatine and Sodium Bicarbonate Coingestion on Multiple Indices of Mechanical Power Output During Repeated Wingate Tests in Trained Men.

    PubMed

    Griffen, Corbin; Rogerson, David; Ranchordas, Mayur; Ruddock, Alan

    2015-06-01

    This study investigated the effects of creatine and sodium bicarbonate coingestion on mechanical power during repeated sprints. Nine well-trained men (age = 21.6 ± 0.9 yr, stature = 1.82 ± 0.05 m, body mass = 80.1 ±12.8 kg) participated in a double-blind, placebo-controlled, counterbalanced, crossover study using six 10-s repeated Wingate tests. Participants ingested either a placebo (0.5 g·kg(-1) of maltodextrin), 20 g·d(-1) of creatine monohydrate + placebo, 0.3 g·kg(-1) of sodium bicarbonate + placebo, or coingestion + placebo for 7 days, with a 7-day washout between conditions. Participants were randomized into two groups with a differential counterbalanced order. Creatine conditions were ordered first and last. Indices of mechanical power output (W), total work (J) and fatigue index (W·s(-1)) were measured during each test and analyzed using the magnitude of differences between groups in relation to the smallest worthwhile change in performance. Compared with placebo, both creatine (effect size (ES) = 0.37-0.83) and sodium bicarbonate (ES = 0.22-0.46) reported meaningful improvements on indices of mechanical power output. Coingestion provided small meaningful improvements on indices of mechanical power output (W) compared with sodium bicarbonate (ES = 0.28-0.41), but not when compared with creatine (ES = -0.21-0.14). Coingestion provided a small meaningful improvement in total work (J; ES = 0.24) compared with creatine. Fatigue index (W·s(-1)) was impaired in all conditions compared with placebo. In conclusion, there was no meaningful additive effect of creatine and sodium bicarbonate coingestion on mechanical power during repeated sprints.

  3. Long-term microwave power drift of a cesium frequency standard and its effect on output frequency

    NASA Technical Reports Server (NTRS)

    Johnson, W. A.; Karuza, Sarunas K.; Voit, Frank J.

    1990-01-01

    It has been shown that the long-term frequency stability of a cesium (Cs) frequency standard is affected by variations in the standard's internal microwave power source. Studies were performed on a commercial Cs frequency standard for a period of 20 days, to determine the stability of its microwave power source. The results were then analyzed statistically, and the effects of microwave power drift on the standard's frequency stability were calculated.

  4. Electromagnetic Launch Vehicle Fairing and Acoustic Blanket Model of Received Power Using FEKO

    NASA Technical Reports Server (NTRS)

    Trout, Dawn H.; Stanley, James E.; Wahid, Parveen F.

    2011-01-01

    Evaluating the impact of radio frequency transmission in vehicle fairings is important to sensitive spacecraft. This paper employees the Multilevel Fast Multipole Method (MLFMM) feature of a commercial electromagnetic tool to model the fairing electromagnetic environment in the presence of an internal transmitter. This work is an extension of the perfect electric conductor model that was used to represent the bare aluminum internal fairing cavity. This fairing model includes typical acoustic blanketing commonly used in vehicle fairings. Representative material models within FEKO were successfully used to simulate the test case.

  5. Near-Field Acoustic Power Level Analysis of F31/A31 Open Rotor Model at Simulated Cruise Conditions, Technical Report II

    NASA Technical Reports Server (NTRS)

    Sree, Dave

    2015-01-01

    Near-field acoustic power level analysis of F31A31 open rotor model has been performed to determine its noise characteristics at simulated cruise flight conditions. The non-proprietary parts of the test data obtained from experiments in the 8x6 supersonic wind tunnel were provided by NASA-Glenn Research Center. The tone and broadband components of total noise have been separated from raw test data by using a new data analysis tool. Results in terms of sound pressure levels, acoustic power levels, and their variations with rotor speed, freestream Mach number, and input shaft power, with different blade-pitch setting angles at simulated cruise flight conditions, are presented and discussed. Empirical equations relating models acoustic power level and input shaft power have been developed. The near-field acoustic efficiency of the model at simulated cruise conditions is also determined. It is hoped that the results presented in this work will serve as a database for comparison and improvement of other open rotor blade designs and also for validating open rotor noise prediction codes.

  6. Two and three dimensional simulation of disk-loaded travelling-wave output structures for high-power klystrons

    SciTech Connect

    Eppley, K.R.

    1994-12-31

    The authors have developed algorithms for designing disk-loaded travelling-wave output structures for X-band klystrons to be used in the SLAC NLC. They use either a four or five cell structure in a {pi}/2 mode. The disk radii are tapered to produce an approximately constant gradient. The matching calculation is not performed on the tapered structure, but rather on a coupler whose input and output cells are the same as the final cell of the tapered structure, and whose interior cells are the same as the penultimate cell in the tapered structure. 2-D calculations using CONDOR model the waveguide as a radial transmission line of adjustable impedance. 3-D calculations with MAFIA model the actual rectangular waveguide and coupling slot. A good match is obtained by adjusting the impedance of the final cell. In 3-D, this requires varying both the radius of the cell and the width of the aperture. When the output cell with the best match is inserted in the tapered structure, they obtain excellent cold-test agreement between the 2-D and 3-D models. They use hot-test simulations with CONDOR to design the structure with maximum efficiency and minimum surface fields. The azimuthal asymmetry due to the coupling iris can increase the peak fields by 20 to 30 percent. They can reduce this problem by making the final cavity with a non-circular cross section. With proper dimensions, they can keep a good match while reducing the azimuthal asymmetry to 6 percent. They have designed circuits at 11.424 Ghz for several different perveances. At 440 kV, microperveance 1.2, they calculate 83 MW, 54 percent efficiency, peak surface field 76 MV/m. At microperveance 0.8, they calculate 60 MW, 58 percent efficiency, peak field 67 MV/m. At 465 kV, microperveance 0.6, they calculate 55 MW, 62 percent efficiency, peak field 63 MV/m.

  7. The Acoustic Analogy: A Powerful Tool in Aeroacoustics with Emphasis on Jet Noise Prediction

    NASA Technical Reports Server (NTRS)

    Farassat, F.; Doty, Michael J.; Hunter, Craig A.

    2004-01-01

    The acoustic analogy introduced by Lighthill to study jet noise is now over 50 years old. In the present paper, Lighthill s Acoustic Analogy is revisited together with a brief evaluation of the state-of-the-art of the subject and an exploration of the possibility of further improvements in jet noise prediction from analytical methods, computational fluid dynamics (CFD) predictions, and measurement techniques. Experimental Particle Image Velocimetry (PIV) data is used both to evaluate turbulent statistics from Reynolds-averaged Navier-Stokes (RANS) CFD and to propose correlation models for the Lighthill stress tensor. The NASA Langley Jet3D code is used to study the effect of these models on jet noise prediction. From the analytical investigation, a retarded time correction is shown that improves, by approximately 8 dB, the over-prediction of aft-arc jet noise by Jet3D. In experimental investigation, the PIV data agree well with the CFD mean flow predictions, with room for improvement in Reynolds stress predictions. Initial modifications, suggested by the PIV data, to the form of the Jet3D correlation model showed no noticeable improvements in jet noise prediction.

  8. Automated Microwave Complex on the Basis of a Continuous-Wave Gyrotron with an Operating Frequency of 263 GHz and an Output Power of 1 kW

    NASA Astrophysics Data System (ADS)

    Glyavin, M. Yu.; Morozkin, M. V.; Tsvetkov, A. I.; Lubyako, L. V.; Golubiatnikov, G. Yu.; Kuftin, A. N.; Zapevalov, V. E.; V. Kholoptsev, V.; Eremeev, A. G.; Sedov, A. S.; Malygin, V. I.; Chirkov, A. V.; Fokin, A. P.; Sokolov, E. V.; Denisov, G. G.

    2016-02-01

    We study experimentally the automated microwave complex for microwave spectroscopy and diagnostics of various media, which was developed at the Institute of Applied Physics of the Russian Academy of Sciences in cooperation with GYCOM Ltd. on the basis of a gyrotron with a frequency of 263 GHz and operated at the first gyrofrequency harmonic. In the process of the experiments, a controllable output power of 0 .1 -1 kW was achieved with an efficiency of up to 17 % in the continuous-wave generation regime. The measured radiation spectrum with a relative width of about 10 -6 and the frequency values measured at various parameters of the device are presented. The results of measuring the parameters of the wave beam, which was formed by a built-in quasioptical converter, as well as the data obtained by measuring the heat loss in the cavity and the vacuum output window are analyzed.

  9. Low-power output-capacitorless low-dropout regulator with adjustable charge injection technique for on-off-keying transmitters

    NASA Astrophysics Data System (ADS)

    Akita, Ippei; Asai, Shochi; Ishida, Makoto

    2014-01-01

    In this paper a low-power low-dropout (LDO) regulator for p power amplifier (PA) in on-off-keying (OOK) transmitters is proposed. The proposed technique needs no external output capacitors, enabling small-area and low-cost implementation. The response of a rapid load change in an OOK transmitter is improved by the proposed adjustable charge injection (ACI) technique that uses timing information of a transmitted data signal. The designed regulator with the ACI technique has been fabricated in a standard 180 nm CMOS process and achieves 100 mVpp dropout voltage ripple. The measured current dissipation is 65 µA at a power supply of 1.8 V.

  10. Two-wavelength quadrature multipoint detection of partial discharge in power transformers using fiber Fabry-Perot acoustic sensors

    NASA Astrophysics Data System (ADS)

    Dong, Bo; Han, Ming; Wang, Anbo

    2012-06-01

    A reliable and low-cost two-wavelength quadrature interrogating method has been developed to demodulate optical signals from diaphragm-based Fabry-Perot interferometric fiber optic sensors for multipoint partial discharge detection in power transformers. Commercial available fused-silica parts (a wafer, a fiber ferrule, and a mating sleeve) and a cleaved optical single mode fiber were bonded together to form an extrinsic Fabry-Perot acoustic sensor. Two lasers with center wavelengths separated by a quarter of the period of sensor interference fringes were used to probe acousticwave- induced diaphragm vibration. A coarse wavelength-division multiplexing (CWDM) add/drop multiplexer was used to separate the reflected two wavelengths before two photo detectors. Optical couplers were used to distribute mixed laser light to each sensor-detector module for multiplexing purpose. Sensor structure, detection system design and experiment results are presented.

  11. High-repetition rate industrial TEA CO2 laser with average output power of 1.5 kW

    NASA Astrophysics Data System (ADS)

    Wan, Chongyi; Liu, Shiming; Zhou, Jinwen; Qi, Jilan; Yang, Xiaola; Wu, Jin; Tan, Rongqing; Wang, Lichun; Mei, Qichu

    1995-03-01

    High power high repetition rate TEA CO2 laser has potential importance in material processing such as shock hardening, glazing, drilling, welding, and cutting for high damage threshold materials, as well as in chemical reaction and isotope separation. This paper describes a transverse-flow closed-cycle UV-preionized TEA CO2 laser with peak pulse power of 20 MW, maximum average power of 1.5 KW at repetition rate of 300 HZ. The laser has compact constructure of gas flow circulation system using tangential fans. With addition of small amounts of H2 and CO to the normal CO2-N2-He gas mixture, one filling sealed operating lifetime is up to millions of pulses. A novel spark gap switch has been developed for very high repetition rate laser discharge in the condition of high pulse power.

  12. Electromagnetic Launch Vehicle Fairing and Acoustic Blanket Model of Received Power Using FEKO

    NASA Technical Reports Server (NTRS)

    Trout, Dawn H.; Stanley, James E.; Wahid, Parveen F.

    2011-01-01

    Evaluating the impact of radio frequency transmission in vehicle fairings is important to electromagnetically sensitive spacecraft. This study employs the multilevel fast multipole method (MLFMM) from a commercial electromagnetic tool, FEKO, to model the fairing electromagnetic environment in the presence of an internal transmitter with improved accuracy over industry applied techniques. This fairing model includes material properties representative of acoustic blanketing commonly used in vehicles. Equivalent surface material models within FEKO were successfully applied to simulate the test case. Finally, a simplified model is presented using Nicholson Ross Weir derived blanket material properties. These properties are implemented with the coated metal option to reduce the model to one layer within the accuracy of the original three layer simulation.

  13. Acoustic agglomeration of power-plant fly ash. A comprehensive semi-annual progress report

    SciTech Connect

    Reethof, G.

    1980-02-01

    Results obtained during the reporting period are presented. The agglomeration of submicron fly ash particles has been studied as a function of sound pressure level, sound frequency, loading, and exposure time. A second generation model of the agglomeration process is being developed. A high-frequency, high-intensity variable speed siren delivering at least 600 W at frequencies up to 4000 Hz has been developed and tested. Details on the design and operation are presented. The agglomeration chamber has been completely cleaned and the aerosol generating system has been rebuilt. A mathematical model of the acoustics of agglomeration is being developed. Preliminary results of computerized electron microscopic scanning of fly ash particles during agglomeration are presented. (DMC)

  14. Influence of thermal deformations of the output windows of high-power laser systems on beam characteristics.

    PubMed

    Peng, Yufeng; Sheng, Zhaoxia; Zhang, Hu; Fan, Xiaowei

    2004-12-10

    By using the well-known Green's function methods, we study the three-dimensional temperature distributions and thermal deformations of the output windows of unstable optical resonators induced by an incident annular laser beam. Some expressions and theoretical profiles of the temperature distributions and thermal deformations as functions of the radius and of the thickness of optical windows are obtained. Moreover, the influence of the thermal deformations of sapphire, silica, and silicon windows within unstable optical resonators on the Strehl ratio and on the far-field laser intensity distribution is also discussed. Under conditions of 50-kW intense laser irradiation during 5 s, the maximum thermal deformation in sapphire, silica, and silicon substrates is 1.993, 0.393, and 6.251 microm, respectively. Under the same conditions the Strehl ratio of sapphire is higher than that of silica. PMID:15617283

  15. Time-domain simulation of constitutive relations for nonlinear acoustics including relaxation for frequency power law attenuation media modeling

    NASA Astrophysics Data System (ADS)

    Jiménez, Noé; Camarena, Francisco; Redondo, Javier; Sánchez-Morcillo, Víctor; Konofagou, Elisa E.

    2015-10-01

    We report a numerical method for solving the constitutive relations of nonlinear acoustics, where multiple relaxation processes are included in a generalized formulation that allows the time-domain numerical solution by an explicit finite differences scheme. Thus, the proposed physical model overcomes the limitations of the one-way Khokhlov-Zabolotskaya-Kuznetsov (KZK) type models and, due to the Lagrangian density is implicitly included in the calculation, the proposed method also overcomes the limitations of Westervelt equation in complex configurations for medical ultrasound. In order to model frequency power law attenuation and dispersion, such as observed in biological media, the relaxation parameters are fitted to both exact frequency power law attenuation/dispersion media and also empirically measured attenuation of a variety of tissues that does not fit an exact power law. Finally, a computational technique based on artificial relaxation is included to correct the non-negligible numerical dispersion of the finite difference scheme, and, on the other hand, improve stability trough artificial attenuation when shock waves are present. This technique avoids the use of high-order finite-differences schemes leading to fast calculations. The present algorithm is especially suited for practical configuration where spatial discontinuities are present in the domain (e.g. axisymmetric domains or zero normal velocity boundary conditions in general). The accuracy of the method is discussed by comparing the proposed simulation solutions to one dimensional analytical and k-space numerical solutions.

  16. Yellow laser light generation by frequency doubling of the output from a master oscillator fiber power amplifier system

    NASA Astrophysics Data System (ADS)

    Ryser, Manuel; Marques, Carlos; Nogueira, Rogério; Romano, Valerio

    2015-03-01

    We present a power-scalable approach for yellow laser-light generation based on standard Ytterbium (Yb) doped fibers. To force the cavity to lase at 1154 nm, far above the gain-maximum, measures must be taken to fulfill lasing condition and to suppress competing amplified spontaneous emission (ASE) in the high-gain region. To prove the principle we built a fiber-laser cavity and a fiber-amplifier both at 1154 nm. In between cavity and amplifier we suppressed the ASE by 70 dB using a fiber Bragg grating (FBG) based filter. Finally we demonstrated efficient single pass frequency doubling to 577 nm with a periodically poled lithium niobate crystal (PPLN). With our linearly polarized 1154 nm master oscillator power fiber amplifier (MOFA) system we achieved slope efficiencies of more than 15 % inside the cavity and 24 % with the fiber-amplifier. The frequency doubling followed the predicted optimal efficiency achievable with a PPLN crystal. So far we generated 1.5 W at 1154nm and 90 mW at 577 nm. Our MOFA approach for generation of 1154 nm laser radiation is power-scalable by using multi-stage amplifiers and large mode-area fibers and is therefore very promising for building a high power yellow laser-light source of several tens of Watt.

  17. Ratings of Perceived Exertion, Heart Rate, and Power Output in Predicting Maximal Oxygen Uptake During Submaximal Cycle Ergometry.

    ERIC Educational Resources Information Center

    Wilmore, Jack H.; And Others

    1986-01-01

    Sixty-two subjects completed a four-stage submaximal cycle ergometer test to determine if estimates of maximal oxygen uptake could be improved by using ratings of perceived exertion singly or in combination with easily obtainable physiological measures. These procedures could be used to estimate the aerobic power of patients and athletes. (MT)

  18. 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.

  19. Pseudopotential approach for dust acoustic solitary waves in dusty plasmas with kappa-distributed ions and electrons and dust grains having power law size distribution

    SciTech Connect

    Banerjee, Gadadhar; Maitra, Sarit

    2015-04-15

    Sagdeev's pseudopotential method is used to study small as well as arbitrary amplitude dust acoustic solitons in a dusty plasma with kappa distributed electrons and ions with dust grains having power law size distribution. The existence of potential well solitons has been shown for suitable parametric region. The criterion for existence of soliton is derived in terms of upper and lower limit for Mach numbers. The numerical results show that the size distribution can affect the existence as well as the propagation characteristics of the dust acoustic solitons. The effect of kappa distribution is also highlighted.

  20. A 4.69-W/mm output power density InAlN/GaN HEMT grown on sapphire substrate

    NASA Astrophysics Data System (ADS)

    Bo, Liu; Zhihong, Feng; Sen, Zhang; Shaobo, Dun; Jiayun, Yin; Jia, Li; Jingjing, Wang; Xiaowei, Zhang; Yulong, Fang; Shujun, Cai

    2011-12-01

    We report high performance InAlN/GaN HEMTs grown on sapphire substrates. The lattice-matched InAlN/GaN HEMT sample showed a high 2DEG mobility of 1210 cm2/(V·s) under a sheet density of 2.6 × 1013 cm-2. Large signal load-pull measurements for a (2 × 100 μm) × 0.25 μm device have been conducted with a drain voltage of 24 V at 10 GHz. The presented results confirm the high performances reachable by InAlN-based technology with an output power density of 4.69 W/mm, a linear gain of 11.8 dB and a peak power-added efficiency of 48%. This is the first report of high performance InAlN/GaN HEMTs in mainland China.

  1. Effects of 4-Week Training Intervention with Unknown Loads on Power Output Performance and Throwing Velocity in Junior Team Handball Players

    PubMed Central

    Sabido, Rafael; Hernández-Davó, Jose Luis; Botella, Javier; Moya, Manuel

    2016-01-01

    Purpose To compare the effect of 4-week unknown vs known loads strength training intervention on power output performance and throwing velocity in junior team handball players. Methods Twenty-eight junior team-handball players (17.2 ± 0.6 years, 1.79 ± 0.07 m, 75.6 ± 9.4 kg)were divided into two groups (unknown loads: UL; known loads: KL). Both groups performed two sessions weekly consisting of four sets of six repetitions of the bench press throw exercise, using the 30%, 50% and 70% of subjects’ individual 1 repetition maximum (1RM). In each set, two repetitions with each load were performed, but the order of the loads was randomised. In the KL group, researchers told the subjects the load to mobilise prior each repetition, while in the UL group, researchers did not provide any information. Maximal dynamic strength (1RM bench press), power output (with 30, 50 and 70% of 1RM) and throwing velocity (7 m standing throw and 9 m jumping throw) were assessed pre- and post-training intervention. Results Both UL and KL group improved similarly their 1RM bench press as well as mean and peak power with all loads. There were significant improvements in power developed in all the early time intervals measured (150 ms) with the three loads (30, 50, 70% 1RM) in the UL group, while KL only improved with 30% 1RM (all the time intervals) and with 70% 1RM (at certain time intervals). Only the UL group improved throwing velocity in both standing (4.7%) and jumping (5.3%) throw (p > 0.05). Conclusions The use of unknown loads has led to greater gains in power output in the early time intervals as well as to increases in throwing velocity compared with known loads. Therefore unknown loads are of significant practical use to increase both strength and in-field performance in a short period of training. PMID:27310598

  2. A low power and low distortion rail-to-rail input/output amplifier using constant current technique

    NASA Astrophysics Data System (ADS)

    Yan, Liu; Yiqiang, Zhao; Shilin, Zhang; Hongliang, Zhao

    2011-04-01

    A rail-to-rail amplifier with constant transconductance, intended for audio processing, is presented. The constant transconductance is obtained by a constant current technique based on the input differential pairs operating in the weak inversion region. MOSFETs working in the weak inversion region have the advantages of low power and low distortion. The proposed rail-to-rail amplifier, fabricated in a standard 0.35 μm CMOS process, occupies a core die area of 75 × 183 μm2. Measured results show that the maximum power consumption is 85.37 μW with a supply voltage of 3.3 V and the total harmonic distortion level is 1.2% at 2 kHz.

  3. Regional thermal specialisation in a mammal: temperature affects power output of core muscle more than that of peripheral muscle in adult mice (Mus musculus).

    PubMed

    James, Rob S; Tallis, Jason; Angilletta, Michael J

    2015-01-01

    In endotherms, such as mammals and birds, internal organs can specialise to function within a narrow thermal range. Consequently, these organs should become more sensitive to changes in body temperature. Yet, organs at the periphery of the body still experience considerable fluctuations in temperature, which could select for lower thermal sensitivity. We hypothesised that the performance of soleus muscle taken from the leg would depend less on temperature than would the performance of diaphragm muscle taken from the body core. Soleus and diaphragm muscles were isolated from mice and subjected to isometric and work-loop studies to analyse mechanical performance at temperatures between 15 and 40 °C. Across this thermal range, soleus muscle took longer to generate isometric force and longer to relax, and tended to produce greater normalised maximal force (stress) than did diaphragm muscle. The time required to produce half of maximal force during isometric tetanus and the time required to relax half of maximal force were both more sensitive to temperature in soleus than they were in diaphragm. However, thermal sensitivities of maximal force during isometric tetani were similar for both muscles. Consistent with our hypothesis, power output (the product of speed and force) was greater in magnitude and more thermally sensitive in diaphragm than it was in soleus. Our findings, when combined with previous observations of muscles from regionally endothermic fish, suggest that endothermy influences the thermal sensitivities of power output in core and peripheral muscles.

  4. Femtosecond laser direct writing of microholes on roughened ZnO for output power enhancement of InGaN light-emitting diodes.

    PubMed

    Zang, Zhigang; Zeng, Xiaofeng; Du, Jihe; Wang, Ming; Tang, Xiaosheng

    2016-08-01

    A significant enhancement of light extraction efficiency from InGaN light-emitting diodes (LEDs) with microhole arrays and roughened ZnO was experimentally demonstrated. The roughened ZnO was fabricated using an Ar and H2 plasma treatment of ZnO films pre-coated on a p-GaN layer. When followed by a femtosecond laser direct writing technique, a periodic array of microholes could be added to the surface. The diameter of the microhole was varied by changing the output power of the femtosecond laser. Compared to conventional LEDs on the same wafer, the output power of LEDs with roughened ZnOs and a microhole (diameter of 2 μm) array was increased by 58.4% when operated with an injection current of 220 mA. Moreover, it was found that LEDs fabricated with roughened ZnO and the microhole array had similar current-voltage (I-V) characteristics to those of conventional LEDs and no degrading effect was observed.

  5. Femtosecond laser direct writing of microholes on roughened ZnO for output power enhancement of InGaN light-emitting diodes.

    PubMed

    Zang, Zhigang; Zeng, Xiaofeng; Du, Jihe; Wang, Ming; Tang, Xiaosheng

    2016-08-01

    A significant enhancement of light extraction efficiency from InGaN light-emitting diodes (LEDs) with microhole arrays and roughened ZnO was experimentally demonstrated. The roughened ZnO was fabricated using an Ar and H2 plasma treatment of ZnO films pre-coated on a p-GaN layer. When followed by a femtosecond laser direct writing technique, a periodic array of microholes could be added to the surface. The diameter of the microhole was varied by changing the output power of the femtosecond laser. Compared to conventional LEDs on the same wafer, the output power of LEDs with roughened ZnOs and a microhole (diameter of 2 μm) array was increased by 58.4% when operated with an injection current of 220 mA. Moreover, it was found that LEDs fabricated with roughened ZnO and the microhole array had similar current-voltage (I-V) characteristics to those of conventional LEDs and no degrading effect was observed. PMID:27472594

  6. Improving the output power of GaN-based light-emitting diode using Ag particles embedded within a SiO2 current blocking layer

    NASA Astrophysics Data System (ADS)

    Park, Jae-Seong; Han, Jaecheon; Seong, Tae-Yeon

    2015-07-01

    GaN-based light-emitting diodes (LEDs) fabricated with Ag particles embedded within a SiO2 current blocking layer (CBL) are demonstrated. The Ag particles varied from 100 to 250 nm in size, and had a density of ∼3.8 × 108 cm-2. The transmittances obtained from GaN/sapphire and Ag particles/GaN/sapphire were 75 and 66% at 450 nm, respectively. The LEDs (chip size: 1000 × 1000 μm2) fabricated with ITO-only, ITO/SiO2 CBL, and ITO/Ag particles/SiO2 CBL showed forward-bias voltages of 3.05, 3.25 and 3.1 V at 20 mA, respectively. The LEDs with the ITO/Ag particles/SiO2 CBL yielded 11.9 and 7.0% higher light output powers (at 20 mA) than the LEDs with the ITO-only and ITO/SiO2 CBL, respectively. The improved output power is explained by the combined effects of the improved extraction and current spreading.

  7. Effect of an increase in gravity on the power output and the rebound of the body in human running.

    PubMed

    Cavagna, G A; Heglund, N C; Willems, P A

    2005-06-01

    The effect of an increase in gravity on the mechanics of running has been studied by using a force platform fixed to the floor of an aircraft undergoing flight profiles, resulting in a simulated gravity of 1.3 g. The power spent to maintain the motion of the centre of mass of the body is approximately 1.3 times greater than on Earth, due to a similar increase of both the power spent against gravity and to sustain the forward speed changes. This indicates that the average vertical displacement per unit distance and the average direction of the push are unchanged. The increase in power is mainly due to an increase in step frequency rather than to an increase in the work done at each step. The increase in step frequency in turn is mainly due to a decreased duration of the effective aerial phase (when the vertical force is less than body weight), rather than an increase in the stiffness of the bouncing system. The maximal speed where step frequency can match the resonant frequency of the bouncing system is increased by approximately 5 km h(-1) at 1.3 g. These results suggest a similar running mechanics at higher gravity, maintained at the expense of greater energy expenditure.

  8. Low-power, cylindrical, air-coupled acoustic levitation/concentration devices: Symmetry breaking of the levitation volume

    NASA Astrophysics Data System (ADS)

    Kaduchak, Gregory; Kogan, Aleksandr S.; Kwiatkowski, Christopher S.; Sinha, Dipen N.

    2002-11-01

    A cylindrical acoustic device for levitation and/or concentration of aerosols and small liquid/solid samples (up to several millimeters in diameter) in air has been developed [Kaduchak et al., Rev. Sci. Instrum. 73, 1332-1336]. It is inexpensive, low-power, and, in its simplest embodiment, does not require accurate alignment of a resonant cavity. It is constructed from a cylindrical PZT tube with thickness-to-radius ratio h/aapprox0.03. The novelty of the device is that the lowest-order breathing mode of the tube is tuned to match a resonant mode of the interior air-filled cylindrical cavity. A high-Q cavity results that is driven very efficiently; drops of water in excess of 1-mm diameter are levitated for approximately 100 mW of input electrical power. The present research addresses modifying the different spatial configurations of the standing wave field within the cavity. By breaking the cylindrical symmetry, it is shown that pressure nodes can be localized for collection or separation of aerosolds or other particulate matter. Several different symmetry-breaking configurations are demonstrated. It is shown that experimental observations of the nodal arrangements agree with theoretical predictions.

  9. Ultrathin, rollable, paper-based triboelectric nanogenerator for acoustic energy harvesting and self-powered sound recording.

    PubMed

    Fan, Xing; Chen, Jun; Yang, Jin; Bai, Peng; Li, Zhaoling; Wang, Zhong Lin

    2015-04-28

    A 125 μm thickness, rollable, paper-based triboelectric nanogenerator (TENG) has been developed for harvesting sound wave energy, which is capable of delivering a maximum power density of 121 mW/m(2) and 968 W/m(3) under a sound pressure of 117 dBSPL. The TENG is designed in the contact-separation mode using membranes that have rationally designed holes at one side. The TENG can be implemented onto a commercial cell phone for acoustic energy harvesting from human talking; the electricity generated can be used to charge a capacitor at a rate of 0.144 V/s. Additionally, owing to the superior advantages of a broad working bandwidth, thin structure, and flexibility, a self-powered microphone for sound recording with rolled structure is demonstrated for all-sound recording without an angular dependence. The concept and design presented in this work can be extensively applied to a variety of other circumstances for either energy-harvesting or sensing purposes, for example, wearable and flexible electronics, military surveillance, jet engine noise reduction, low-cost implantable human ear, and wireless technology applications. PMID:25790372

  10. Ultrathin, rollable, paper-based triboelectric nanogenerator for acoustic energy harvesting and self-powered sound recording.

    PubMed

    Fan, Xing; Chen, Jun; Yang, Jin; Bai, Peng; Li, Zhaoling; Wang, Zhong Lin

    2015-04-28

    A 125 μm thickness, rollable, paper-based triboelectric nanogenerator (TENG) has been developed for harvesting sound wave energy, which is capable of delivering a maximum power density of 121 mW/m(2) and 968 W/m(3) under a sound pressure of 117 dBSPL. The TENG is designed in the contact-separation mode using membranes that have rationally designed holes at one side. The TENG can be implemented onto a commercial cell phone for acoustic energy harvesting from human talking; the electricity generated can be used to charge a capacitor at a rate of 0.144 V/s. Additionally, owing to the superior advantages of a broad working bandwidth, thin structure, and flexibility, a self-powered microphone for sound recording with rolled structure is demonstrated for all-sound recording without an angular dependence. The concept and design presented in this work can be extensively applied to a variety of other circumstances for either energy-harvesting or sensing purposes, for example, wearable and flexible electronics, military surveillance, jet engine noise reduction, low-cost implantable human ear, and wireless technology applications.

  11. Lightweight multiple output converter development

    NASA Technical Reports Server (NTRS)

    Kisch, J. J.; Martinelli, R. M.

    1978-01-01

    A high frequency, multiple output power conditioner was developed and breadboarded using an eight-stage capacitor diode voltage multiplier to provide +1200 Vdc, and a three-stage for -350 Vdc. In addition, two rectifier bridges were capacitively coupled to the eight-stage multiplier to obtain 0.5 and 0.65 a dc constant current outputs referenced to +1200 Vdc. Total power was 120 watts, with an overall efficiency of 85 percent at the 80 kHz operating frequency. All outputs were regulated to three percent or better, with complete short circuit protection. The power conditioner component weight and efficiency were compared to the equivalent four outputs of the 10 kHz conditioner for the 8 cm ion engine. Weight reduction for the four outputs was 557 grams; extrapolated in the same ratio to all nine outputs, it would be 1100 to 1400 grams.

  12. Method for reducing the amount of nox and for raising the output of a gas turbine power station of the type utilizing an air reservoir, and a gas turbine power station, of this type, operating in accordance with this method

    SciTech Connect

    Zaugg, P.

    1985-06-11

    The gas turbine power station, which is of the type utilizing an air reservoir, and is operated in accordance with the method for reducing the amount of NO /SUB x/ and for raising output, possesses an intermediate condensate-vessel and a main condensate-vessel for receiving the condensate which is produced in the compressor-air coolers. From the main condensate vessel, the condensate is introduced into the combustion chambers of the gas turbine, optionally after passing through a recuperator.

  13. Acoustic emission intrusion detector

    DOEpatents

    Carver, Donald W.; Whittaker, Jerry W.

    1980-01-01

    An intrusion detector is provided for detecting a forcible entry into a secured structure while minimizing false alarms. The detector uses a piezoelectric crystal transducer to sense acoustic emissions. The transducer output is amplified by a selectable gain amplifier to control the sensitivity. The rectified output of the amplifier is applied to a Schmitt trigger circuit having a preselected threshold level to provide amplitude discrimination. Timing circuitry is provided which is activated by successive pulses from the Schmitt trigger which lie within a selected time frame for frequency discrimination. Detected signals having proper amplitude and frequency trigger an alarm within the first complete cycle time of a detected acoustical disturbance signal.

  14. Influence of ultrasound power on acoustic streaming and micro-bubbles formations in a low frequency sono-reactor: mathematical and 3D computational simulation.

    PubMed

    Sajjadi, Baharak; Raman, Abdul Aziz Abdul; Ibrahim, Shaliza

    2015-05-01

    This paper aims at investigating the influence of ultrasound power amplitude on liquid behaviour in a low-frequency (24 kHz) sono-reactor. Three types of analysis were employed: (i) mechanical analysis of micro-bubbles formation and their activities/characteristics using mathematical modelling. (ii) Numerical analysis of acoustic streaming, fluid flow pattern, volume fraction of micro-bubbles and turbulence using 3D CFD simulation. (iii) Practical analysis of fluid flow pattern and acoustic streaming under ultrasound irradiation using Particle Image Velocimetry (PIV). In mathematical modelling, a lone micro bubble generated under power ultrasound irradiation was mechanistically analysed. Its characteristics were illustrated as a function of bubble radius, internal temperature and pressure (hot spot conditions) and oscillation (pulsation) velocity. The results showed that ultrasound power significantly affected the conditions of hotspots and bubbles oscillation velocity. From the CFD results, it was observed that the total volume of the micro-bubbles increased by about 4.95% with each 100 W-increase in power amplitude. Furthermore, velocity of acoustic streaming increased from 29 to 119 cm/s as power increased, which was in good agreement with the PIV analysis.

  15. Investigation of temperature influence on output performances of high-power cladding-pumped Er,Yb co-doped fiber laser

    NASA Astrophysics Data System (ADS)

    Chen, Wenting; Sha, Jianjian; Wang, Yong; Shen, Deyuan

    2013-03-01

    Effect of the fiber's temperature on lasing performance is investigated in high-power, cladding-pumped Er, Yb co-doped fiber laser system. A three-layer symmetric cylindrical model is applied to describe the temperature distribution of the fiber under natural air convection. Radial temperature distribution of the fiber is calculated with consideration of the quantum defect heat, the heat from the absorption of spontaneous emission, and the convection and radiation at the heat transfer boundaries. The steady-state theoretical model based on rate equations takes into account of the energy transfers between Er3+-ions and Yb3+-ions and a fraction of nonparticipatory Yb3+-ions. Shooting method and Newton iteration method are used to solve the boundary-value problems under different environmental temperatures, pump powers and reflectivities at the fiber ends. Numerical simulations are consistent with experimental results and show that increasing the fiber's temperature is an effective strategy to suppress the 1 μm parasitic lasing and improve the lasing performance at 1.5 μm, a similar phenomenon is found with enhancing doping concentrations of the two ions and decreasing the reflectivities at the fiber ends. Our numerical results present a theoretical guideline for further improving the laser performance in terms of output power of ~1.5 μm in high-power Er,Yb-doped fiber laser systems.

  16. The Sagnac-configured fiber optic calorimeter: An investigation of an improved non-destructive methodology for determining the thermal power output of heat-producing nuclear materials

    NASA Astrophysics Data System (ADS)

    Bayliss, Stephen Carlton

    An essential component in an ever-expanding global nuclear economy is the nondestructive assay (NDA) of nuclear materials. Accurate accounting of these materials helps to insure the safe handling and disposal of them and the accurate monitoring of these materials can help prevent their diversion. A particularly useful and important NDA technique has proven to be isothermal calorimetry. With state-of-the-art calorimeters, heat rates as low as a few milliwatts can be measured, which correspond to approximately one gram of plutonium or one milligram of tritium; two materials of particular interest. In addition, calorimetry is relatively insensitive to the matrix of the sample. This work reports on the development of a calorimeter technique based on fiber optics, which can greatly increase the sensitivity of the calorimeter compared with present day devices. Specifically, this device uses an optical fiber configuration based on the Sagnac interferometer. Fundamentally, the optical fiber is replacing the resistive wire used in conventional calorimeters. The optical fiber is wrapped around two "thermels;" a reference and a sample thermel; the thermal sample to be measured is placed in the sample thermel. The light within the optical fiber of the sample arm experiences a change in phase due to the change in the index of refraction caused by the thermal load. When this light mixes with the light from the reference arm, a change in the light intensity results. An electro-optic receiver converts the time-varying light intensity to a time-varying voltage output. It is this voltage output that is stored and analyzed. A prototype fiber calorimeter has been built and proved capable of measuring heat loads in the microwatt regime. This sensitivity represents a factor of a one thousand-fold improvement over conventional calorimeters. This would allow plutonium samples as small as one milligram to be measured and microgram quantities of tritium. In addition, gram quantities of 93

  17. Increasing reducing power output (NADH) of glucose catabolism for reduction of xylose to xylitol by genetically engineered Escherichia coli AI05.

    PubMed

    Iverson, Andrew; Garza, Erin; Zhao, Jinfang; Wang, Yongze; Zhao, Xiao; Wang, Jinhua; Manow, Ryan; Zhou, Shengde

    2013-07-01

    Anaerobic homofermentative production of reduced products requires additional reducing power (NADH and/or NADPH) output from glucose catabolism. Previously, with an anaerobically expressed pyruvate dehydrogenase operon (aceEF-lpd), we doubled the reducing power output to four NADH per glucose (or 1.2 xylose) catabolized anaerobically, which satisfied the NADH requirement to establish a non-transgenic homoethanol pathway (1 glucose or 1.2 xylose --> 2 acetyl-CoA + 4 NADH --> 2 ethanol) in the engineered strain, Escherichia coli SZ420 (∆frdBC ∆ldhA ∆ackA ∆focA-pflB ∆pdhR::pflBp6-pflBrbs-aceEF-lpd). In this study, E. coli SZ420 was further engineered for reduction of xylose to xylitol by (1) deleting the alcohol dehydrogenase gene (adhE) to divert NADH from the ethanol pathway; (2) deleting the glucose-specific PTS permease gene (ptsG) to eliminate catabolite repression and allow simultaneous uptake of glucose and xylose; (3) cloning the aldose reductase gene (xylI) of Candida boidinii to reduce xylose to xylitol. The resulting strain, E. coli AI05 (pAGI02), could in theory simultaneously uptake glucose and xylose, and utilize glucose as a source of reducing power for the reduction of xylose to xylitol, with an expected yield of four xylitol for each glucose consumed (YRPG = 4) under anaerobic conditions. In resting cell fermentation tests using glucose and xylose mixtures, E. coli AI05 (pAGI02) achieved an actual YRPG value of ~3.6, with xylitol as the major fermentation product and acetate as the by-product.

  18. Estimated times to exhaustion and power outputs at the gas exchange threshold, physical working capacity at the rating of perceived exertion threshold, and respiratory compensation point.

    PubMed

    Bergstrom, Haley C; Housh, Terry J; Zuniga, Jorge M; Camic, Clayton L; Traylor, Daniel A; Schmidt, Richard J; Johnson, Glen O

    2012-10-01

    The purposes of this study were to compare the power outputs and estimated times to exhaustion (T(lim)) at the gas exchange threshold (GET), physical working capacity at the rating of perceived exertion threshold (PWC(RPE)), and respiratory compensation point (RCP). Three male and 5 female subjects (mean ± SD: age, 22.4 ± 2.8 years) performed an incremental test to exhaustion on an electronically braked cycle ergometer to determine peak oxygen consumption rate, GET, and RCP. The PWC(RPE) was determined from ratings of perceived exertion data recorded during 3 continuous workbouts to exhaustion. The estimated T(lim) values for each subject at GET, PWC(RPE), and RCP were determined from power curve analyses (T(lim) = ax(b)). The results indicated that the PWC(RPE) (176 ± 55 W) was not significantly different from RCP (181 ± 54 W); however, GET (155 ± 42 W) was significantly less than PWC(RPE) and RCP. The estimated T(lim) for the GET (26.1 ± 9.8 min) was significantly greater than PWC(RPE) (14.6 ± 5.6 min) and RCP (11.2 ± 3.1 min). The PWC(RPE) occurred at a mean power output that was 13.5% greater than the GET and, therefore, it is likely that the perception of effort is not driven by the same mechanism that underlies the GET (i.e., lactate buffering). Furthermore, the PWC(RPE) and RCP were not significantly different and, therefore, these thresholds may be associated with the same mechanisms of fatigue, such as increased levels of interstitial and (or) arterial [K⁺]. PMID:22716291

  19. Mechanisms underlying enhancements in muscle force and power output during maximal cycle ergometer exercise induced by chronic β2-adrenergic stimulation in men.

    PubMed

    Hostrup, Morten; Kalsen, Anders; Onslev, Johan; Jessen, Søren; Haase, Christoffer; Habib, Sajad; Ørtenblad, Niels; Backer, Vibeke; Bangsbo, Jens

    2015-09-01

    The study was a randomized placebo-controlled trial investigating mechanisms by which chronic β2-adrenergic stimulation enhances muscle force and power output during maximal cycle ergometer exercise in young men. Eighteen trained men were assigned to an experimental group [oral terbutaline 5 mg/30 kg body weight (bw) twice daily (TER); n = 9] or a control group [placebo (PLA); n = 9] for a 4-wk intervention. No changes were observed with the intervention in PLA. Isometric muscle force of the quadriceps increased (P ≤ 0.01) by 97 ± 29 N (means ± SE) with the intervention in TER compared with PLA. Peak and mean power output during 30 s of maximal cycling increased (P ≤ 0.01) by 32 ± 8 and 25 ± 9 W, respectively, with the intervention in TER compared with PLA. Maximal oxygen consumption (V̇o2max) and time to fatigue during incremental cycling did not change with the intervention. Lean body mass increased by 1.95 ± 0.8 kg (P ≤ 0.05) with the intervention in TER compared with PLA. Change in single fiber cross-sectional area of myosin heavy chain (MHC) I (1,205 ± 558 μm(2); P ≤ 0.01) and MHC II fibers (1,277 ± 595 μm(2); P ≤ 0.05) of the vastus lateralis muscle was higher for TER than PLA with the intervention, whereas no changes were observed in MHC isoform distribution. Expression of muscle proteins involved in growth, ion handling, lactate production, and clearance increased (P ≤ 0.05) with the intervention in TER compared with PLA, with no change in oxidative enzymes. Our observations suggest that muscle hypertrophy is the primary mechanism underlying enhancements in muscle force and peak power during maximal cycling induced by chronic β2-adrenergic stimulation in humans.

  20. MEMS Based Acoustic Array

    NASA Technical Reports Server (NTRS)

    Sheplak, Mark (Inventor); Nishida, Toshikaza (Inventor); Humphreys, William M. (Inventor); Arnold, David P. (Inventor)

    2006-01-01

    Embodiments of the present invention described and shown in the specification aid drawings include a combination responsive to an acoustic wave that can be utilized as a dynamic pressure sensor. In one embodiment of the present invention, the combination has a substrate having a first surface and an opposite second surface, a microphone positioned on the first surface of the substrate and having an input and a first output and a second output, wherein the input receives a biased voltage, and the microphone generates an output signal responsive to the acoustic wave between the first output and the second output. The combination further has an amplifier positioned on the first surface of the substrate and having a first input and a second input and an output, wherein the first input of the amplifier is electrically coupled to the first output of the microphone and the second input of the amplifier is electrically coupled to the second output of the microphone for receiving the output sinual from the microphone. The amplifier is spaced from the microphone with a separation smaller than 0.5 mm.