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Sample records for acoustic output power

  1. Measurement of the total acoustic output power of HITU transducers

    NASA Astrophysics Data System (ADS)

    Jenderka, Klaus-V.; Beissner, Klaus

    2010-03-01

    The majority of High Intensity Therapeutic Ultrasound (HITU) applications use strongly focused ultrasound fields generating very high local intensities in the focal region. The metrology of these high-power ultrasound fields is a challenge for the established measurement procedures and devices. This paper describes the results of measurements by means of the radiation force for a total acoustic output power up to 400 W at 1.5 MHz and up to 200 W at 2.45 MHz. For this purpose, a radiation force balance set-up was adapted for the determination of large acoustic output powers. For two types of HITU transducers, the relationship between the total acoustic output power and the applied net electrical power was determined at close transducer-target distance. Further, dependence of the measured electro-acoustic radiation conductance on the transducer-target distance was investigated at reduced power levels, considering the appearance of focal anomalies. Concluding, a list of the main uncertainty contributions, and an estimate of the uncertainty for the used radiation force balance set-up is given for measurements at high power levels.

  2. Enhanced output power by eigenfrequency shift in acoustic energy harvester

    NASA Astrophysics Data System (ADS)

    Li, Bin; You, Jeong Ho

    2014-04-01

    In our previous studies, multiple piezoelectric cantilever plates were placed inside a quarter-wavelength straight tube resonator to harvest low frequency acoustic energy. To investigate the modification of eigenmodes in the tube resonator due to the presence of piezoelectric plates, the eigenfrequency shift properties by introducing single and multiple rectangular blockages in open-closed ducts are studied by using 1D segmented Helmholtz equations, Webster horn equation, and finite element simulations. The first-mode eigenfrequency of the duct is reduced when the blockage is placed near the open inlet. The decrease of eigenfrequency leads to the enhancement of absorbed acoustic power in the duct. Furthermore, the first half of the tube resonator possesses high pressure gradient resulting in larger driving forces for the vibration motion of piezoelectric plates. Therefore, in our harvesters, it is better to place the piezoelectric plates in the first half of the tube resonator to obtain high output voltage and power.

  3. 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.

  4. 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.

  5. 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.

  6. High Power Amplifier Harmonic Output Level Measurement

    NASA Technical Reports Server (NTRS)

    Perez, R. M.; Hoppe, D. J.; Khan, A. R.

    1995-01-01

    A method is presented for the measurement of the harmonic output power of high power klystron amplifiers, involving coherent hemispherical radiation pattern measurements of the radiated klystron output. Results are discussed for the operation in saturated and unsaturated conditions, and with a waveguide harmonic filter included.

  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. Caffeine, maximal power output and fatigue.

    PubMed Central

    Williams, J H; Signorile, J F; Barnes, W S; Henrich, T W

    1988-01-01

    The purpose of this investigation was to determine the effects of caffeine ingestion on maximal power output and fatigue during short term, high intensity exercise. Nine adult males performed 15 s maximal exercise bouts 60 min after ingestion of caffeine (7 mg.kg-1) or placebo. Exercise bouts were carried out on a modified cycle ergometer which allowed power output to be computed for each one-half pedal stroke via microcomputer. Peak power output under caffeine conditions was not significantly different from that obtained following placebo ingestion. Similarly, time to peak power, total work, power fatigue index and power fatigue rate did not differ significantly between caffeine and placebo conditions. These results suggest that caffeine ingestion does not increase one's maximal ability to generate power. Further, caffeine does not alter the rate or magnitude of fatigue during high intensity, dynamic exercise. PMID:3228680

  9. 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.

  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. Acoustic power of a moving point source in a moving medium

    NASA Technical Reports Server (NTRS)

    Cole, J. E., III; Sarris, I. I.

    1976-01-01

    The acoustic power output of a moving point-mass source in an acoustic medium which is in uniform motion and infinite in extent is examined. The acoustic medium is considered to be a homogeneous fluid having both zero viscosity and zero thermal conductivity. Two expressions for the acoustic power output are obtained based on a different definition cited in the literature for the average energy-flux vector in an acoustic medium in uniform motion. The acoustic power output of the source is found by integrating the component of acoustic intensity vector in the radial direction over the surface of an infinitely long cylinder which is within the medium and encloses the line of motion of the source. One of the power expressions is found to give unreasonable results even though the flow is uniform.

  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. 47 CFR 2.1046 - Measurements required: RF power output.

    Code of Federal Regulations, 2013 CFR

    2013-10-01

    ... 47 Telecommunication 1 2013-10-01 2013-10-01 false Measurements required: RF power output. 2.1046... Measurements required: RF power output. (a) For transmitters other than single sideband, independent sideband and controlled carrier radiotelephone, power output shall be measured at the RF output terminals...

  14. Laboratory measurement of human power output during maximum intensity exercise

    NASA Astrophysics Data System (ADS)

    Lakomy, Henryk K. A.

    1993-11-01

    The power output of an athlete decreases rapidly with time. The author describes different ways of measuring power output, including a unique method developed at Loughborough University for measuring the power developed by a sprint runner.

  15. Dual output acoustic wave sensor for molecular identification

    SciTech Connect

    Frye, G.C.; Martin, S.J.

    1990-10-03

    The invention comprises a method for the identification and quantification of sorbed chemical species onto a coating of a device capable of generating and receiving an acoustic wave, by measuring the changes in the velocity of the acoustic wave resulting from the sorption of the chemical species into the coating as the wave travels through the coating and by measuring the changes in the attenuation of an acoustic wave resulting from the sorption of the chemical species into the coating as the wave travels through the coating. The inventive method further correlates the magnitudes of the changes of velocity with respect to changes of the attenuation of the acoustic wave to identify the sorbed chemical species. The absolute magnitudes of the velocity changes or the absolute magnitude of the attenuation changes are used to determine the concentration of the identified chemical species.

  16. Acoustic thermometric data on blood flow and thermal output in forearm under physical pressure

    NASA Astrophysics Data System (ADS)

    Anosov, A. A.; Belyaev, R. V.; Vilkov, V. A.; Kazanskii, A. S.; Kuryatnikova, N. A.; Mansfel'd, A. D.

    2013-07-01

    The influence of blood flow and thermal output on temperature changes in the human forearm under physical pressure is studied by acoustic thermometry. Compression of the shoulder with a tourniquet decreases blood flow, which make it possible to evaluate the thermal output characteristics only. In calculating the depth temperature of the forearm, the thermal conductivity equation was used and blood flow and additional thermal output sources were taken into account. According to the calculations in which the experimental data were used, the peak depth temperature of the forearm at rest is 36°C. Due to thermal output alone (without blood flow), physical pressure increases this temperature to 37°C, and when both factors are considered, the temperature rises to 38°C. The experiments in question have allowed us to test acoustic thermographic method on subjects, which is an important step in adopting acoustic thermography in clinical practice.

  17. 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).

  18. 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. PMID:25680145

  19. Multiple high voltage output DC-to-DC power converter

    NASA Technical Reports Server (NTRS)

    Cronin, Donald L. (Inventor); Farber, Bertrand F. (Inventor); Gehm, Hartmut K. (Inventor); Goldin, Daniel S. (Inventor)

    1977-01-01

    Disclosed is a multiple output DC-to-DC converter. The DC input power is filtered and passed through a chopper preregulator. The chopper output is then passed through a current source inverter controlled by a squarewave generator. The resultant AC is passed through the primary winding of a transformer, with high voltages induced in a plurality of secondary windings. The high voltage secondary outputs are each solid-state rectified for passage to individual output loads. Multiple feedback loops control the operation of the chopper preregulator, one being responsive to the current through the primary winding and another responsive to the DC voltage level at a selected output.

  20. Power absorption in acoustically driven ferromagnetic resonance

    NASA Astrophysics Data System (ADS)

    Labanowski, D.; Jung, A.; Salahuddin, S.

    2016-01-01

    Surface acoustic waves (SAWs) have recently been used to drive ferromagnetic resonance by exploiting the coupling between strain and magnetization in magnetostrictive materials in a technique called acoustically driven ferromagnetic resonance (ADFMR). In this work, we quantitatively examine the power absorbed by the magnetic elements in such systems. We find that power absorption scales exponentially with the length of the magnetic element in the direction of SAW propagation, with the rate of scaling set by the thickness of magnetic material. In addition, we find that ADFMR behaves consistently across a wide range of input power values (>65 dB). Our results indicate that devices such as filters, oscillators, and sensors can be designed that operate with very low power, yet provide high tunability.

  1. A novel pyroelectric method of determining ultrasonic transducer output power: device concept, modeling, and preliminary studies.

    PubMed

    Zeqiri, Bajram; Gélat, Pierre N; Barrie, Jill; Bickley, Catherine J

    2007-11-01

    This paper describes a new thermally based method of monitoring acoustic output power generated by ultrasonic transducers. Its novelty lies in the exploitation of the pyroelectric properties of a thin membrane of polyvinylidene fluoride (PVDF). The membrane is backed by a thick layer of polyurethane rubber that is extremely attenuating to ultrasound, with the result that the majority of the applied acoustic power is absorbed within a few millimeters of the membrane-backing interface. Through the resultant rapid increase in temperature of the membrane, a voltage is generated across its electrodes whose magnitude is proportional to the rate of change of temperature with respect to time. Changes in the pyroelectric voltage generated by switching the transducer ON and OFF are related to the acoustic power delivered by the transducer. Features of the technique are explored through the development of a simple one-dimensional model. An experimental evaluation of the potential secondary measurement technique is also presented, covering the frequency range 1 to 5 MHz, for delivered powers up to a watt. Predictions of the sensor output signals, as well as the frequency dependent sensitivity, are in good agreement with observation. The potential of the new method as a simple, rapid means of providing traceable ultrasonic power measurements is outlined. PMID:18051166

  2. 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. PMID:16151832

  3. 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. PMID:24595200

  4. 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

  5. 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)

  6. 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. PMID:26701343

  7. 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. PMID:21786895

  8. Experimental and theoretical identification of a four- acoustic-inputs/two-vibration-outputs hearing system

    NASA Astrophysics Data System (ADS)

    Balaji, P. A.

    1999-07-01

    A cricket's ear is a directional acoustic sensor. It has a remarkable level of sensitivity to the direction of sound propagation in a narrow frequency bandwidth of 4-5 KHz. Because of its complexity, the directional sensitivity has long intrigued researchers. The cricket's ear is a four-acoustic-inputs/two-vibration-outputs system. In this dissertation, this system is examined in depth, both experimentally and theoretically, with a primary goal to understand the mechanics involved in directional hearing. Experimental identification of the system is done by using random signal processing techniques. Theoretical identification of the system is accomplished by analyzing sound transmission through complex trachea of the ear. Finally, a description of how the cricket achieves directional hearing sensitivity is proposed. The fundamental principle involved in directional heating of the cricket has been utilized to design a device to obtain a directional signal from non- directional inputs.

  9. Impact of voltage and capacity on the electrical and acoustic output of intracorporeal electrohydraulic lithotripsy.

    PubMed

    Vorreuther, R; Engelking, R

    1992-01-01

    The electrical and acoustic output created by the spark discharge for electrohydraulic lithotripsy at the tip of a 3.3-F probe was evaluated. Spark generation was achieved by variable combinations of voltage and capacity. The effective electrical output was determined by means of a high-voltage probe, a current coil and a digital oscilloscope. Peak pressures, rise times and pulse width of the shock waves were recorded using a polyvinylidene difluoride needle hydrophone in 0.9% NaCl solution at a distance of 10 mm. The effective electrical output is lower than the calculated output, due to inductivities, capacities and resistances of the cables and plugs. The life of the probes is markedly shorter when a combination of high voltage and low capacity is used than with low voltage and high capacity corresponding to the same energy. The peak pressure and the slope of the shock front depend solely on the voltage, while the pulse width is correlated with the capacity. The pulse intensity integral of the shock wave is likely to be the best equivalent to the applied energy. PMID:1455568

  10. 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

  11. 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.

  12. Optimizing thermoacoustic regenerators for maximum amplification of acoustic power.

    PubMed

    Holzinger, Tobias; Emmert, Thomas; Polifke, Wolfgang

    2014-11-01

    Identifying optimum design parameters and operating conditions of thermoacoustic engines or refrigerators is crucial for the further development of such devices. This publication proposes an optimization criterion for the stack of a thermoacoustic device with the objective of maximizing the amplification of acoustic energy by the stack. For this purpose, the stack is described as an acoustic multi-port, represented mathematically by its scattering matrix. It is shown how the scattering matrix may be deduced from the standard thermo-acoustic governing equations. Then an acoustic power balance is deduced from the scattering matrix. The spectral norm and the eigenvectors of the scattering matrix identify optimal acoustic states. Stack design operating parameters and frequencies with maximum amplification of acoustic power are identified for various stack configurations. The corresponding acoustic states are interpreted physically. PMID:25373945

  13. High output power electric motors with bulk HTS elements

    NASA Astrophysics Data System (ADS)

    Kovalev, L. K.; Ilushin, K. V.; Kovalev, K. L.; Penkin, V. T.; Poltavets, V. N.; Koneev, S. M.-A.; Akimov, I. I.; Gawalek, W.; Oswald, B.; Krabbes, G.

    2003-04-01

    New types of electric machines with the rotors containing bulk HTS (YBCO and Bi-Ag) elements are presented. Different schematics of hysteresis, reluctance, “trapped field” and composed synchronous HTS machines are discussed. The two-dimensional mathematical models describing the processes in such types of HTS machines were developed on the basis of the theoretical analysis of the electrodynamic and hysteresis processes in the single-domain and polycrystal YBCO ceramic samples and plate shape Bi-Ag elements. The test results of the series of hysteresis, reluctance, “trapped field” and composed with permanent magnets HTS motors with output power rating 0.1-18 kW and current frequency 50 and 400 Hz are given. These results show that in the media of liquid nitrogen the specific output power per one weight unit of HTS motors is 4-7 times better than for conventional electric machines. Comparison of the theoretical and experimental characteristics of the developed HTS motors show that they are in good agreement. The test results for liquid nitrogen cryogenic pump system with hysteresis 500 W HTS motor are discussed. The designs and first test results of HTS motor operating in the media of liquid nitrogen with output power 100 kW and power factor more than 0.8 are given. Future development and applications of new types of HTS motors for aerospace technology, on-land industry and transport systems are discussed.

  14. Halbach array generator/motor having mechanically regulated output voltage and mechanical power output

    SciTech Connect

    Post, Richard F.

    2005-06-14

    A motor/generator has its stationary portion, i.e., the stator, positioned concentrically within its rotatable element, i.e., the rotor, along the axis of rotation of the rotor. The rotor includes a Halbach array of magnets. The voltage and power outputs are regulated by varying the radial gap in between the stator windings and the rotating Halbach array. The gap is varied by extensible and retractable supports attached to the stator windings that can move the windings in a radial direction.

  15. New concept input and output systems for high power gyroklystron

    NASA Astrophysics Data System (ADS)

    Xu, Xiaoxi; Lawson, W.; Liu, C.; Cheng, J.; Anderson, J.; Hogan, B.; Granatstein, V. L.; Reiser, M.

    1999-07-01

    In order to obtain the high mode purity of a TE011 mode in an overmoded gyroklystron input cavity while maintaining high coupling efficiency, a coaxial dual-cavity input structure with an outer TE411 mode and an inner TE011 mode coaxial cavity has been designed to get a reasonable low Q and to avoid mode distortion due to a single coupling aperture between an input waveguide and input cavity. A quality factor of 73 and a resonant frequency of 8.570 GHz with high mode purity have been obtained for the inner TE011 mode coaxial cavity. Furthermore, in order to inject the output power of a second harmonic gyroklystron (17.136 GHz) into our future pulse composer and accelerator system, a coaxial TE021 output cavity with a TE02-TE01 mode converter is proposed and designed as the output structure of the gyroklystron. The output power can be extracted radially, and at the same time the TE02 mode is converted to TE01 mode into a inner coaxial waveguide.

  16. 76 FR 52734 - Underwater Locating Devices (Acoustic) (Self-Powered)

    Federal Register 2010, 2011, 2012, 2013, 2014

    2011-08-23

    ...This notice announces the planned revocation of all Technical Standard Order authorizations (TSOA) issued for the production of Underwater Locating Devices (Acoustic) (Self-Powered) manufactured to the TSO-C121 and TSO-C121a specifications. These actions are necessary because the planned issuance of TSO-C121b, Underwater Locating Devices (Acoustic) (Self-Powered), with a minimum performance......

  17. 77 FR 13174 - Underwater Locating Devices (Acoustic) (Self-Powered)

    Federal Register 2010, 2011, 2012, 2013, 2014

    2012-03-05

    ...This is a confirmation notice for the planned revocation of all Technical Standard Order authorizations issued for the production of Underwater Locating Devices (Acoustic) (Self-Powered) manufactured to the TSO-C121 and TSO-C121a specifications. These actions are necessary because the planned issuance of TSO-C121b, Underwater Locating Devices (Acoustic) (Self-Powered), minimum performance......

  18. 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

  19. 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

  20. 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.

  1. Time reversal multiple-input/multiple-output acoustic communication enhanced by parallel interference cancellation.

    PubMed

    Song, Aijun; Badiey, Mohsen

    2012-01-01

    Multiple-input/multiple-output (MIMO) techniques can lead to significant improvements of underwater acoustic communication capabilities. In this paper, receivers based on time reversal processing are developed for high frequency underwater MIMO channels. Time reversal followed by a single channel decision feedback equalizer, aided by frequent channel updates, is used to compensate for the time-varying inter-symbol interference. A parallel interference cancellation method is incorporated to suppress the co-channel interference in the MIMO system. The receiver performance is demonstrated by a 2008 shallow water experiment in Kauai, Hawaii. In the experiment, high frequency MIMO signals centered at 16 kHz were transmitted every hour during a 35 h period from an 8-element source array to a wide aperture 16-element vertical receiving array at 4 km range. The interference cancellation method is shown to generate significant performance enhancement, on average 2-4 dB in the output signal-to-noise ratio per data stream, throughout the 35 h MIMO transmissions. Further, communication performance and achieved data rates exhibit significant changes over the 35 h period as a result of stratification of the water column. PMID:22280591

  2. 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. PMID:22134883

  3. 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.

  4. Estimation of the detection range of a hydroacoustic system based on the acoustic power flux receiver

    NASA Astrophysics Data System (ADS)

    Gordienko, V. A.; Krasnopistsev, N. V.; Nasedkin, A. V.; Nekrasov, V. N.

    2007-11-01

    Approaches to estimating the detection range of systems based on vector receivers are considered. The approaches rely on a detailed analysis of the process of signal’s acoustic power flux formation in the presence of ambient sea noise and uncover the signal information parameters at the receiver output that provide the required statistically confident range of weak signal detection under these conditions. Based on the sonar equations and the known fundamental relationships between the outputs of a pressure receiver and a vector receiver for signal and noise, estimates of the maximum possible gain in the detection range of an acoustic power flux receiver are considered as a function of anisotropy of the ambient noise field in the area.

  5. 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.

  6. 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. PMID:25438839

  7. Increased photovoltaic power output via diffractive spectrum separation.

    PubMed

    Kim, Ganghun; Dominguez-Caballero, Jose A; Lee, Howard; Friedman, Daniel J; Menon, Rajesh

    2013-03-22

    In this Letter, we report the preliminary demonstration of a new paradigm for photovoltaic power generation that utilizes a broadband diffractive-optical element (BDOE) to efficiently separate sunlight into laterally spaced spectral bands. These bands are then absorbed by single-junction photovoltaic cells, whose band gaps correspond to the incident spectral bands. We designed such BDOEs by utilizing a modified version of the direct-binary-search algorithm. Gray scale lithography was used to fabricate these multilevel optics. They were experimentally characterized with an overall optical efficiency of 70% over a wavelength range of 350-1100 nm, which was in excellent agreement with simulation predictions. Finally, two prototype devices were assembled: one with a pair of copper indium gallium selenide based photovoltaic devices, and another with GaAs and c-Si photovoltaic devices. These devices demonstrated an increase in output peak electrical power of ∼ 42% and ∼ 22%, respectively, under white-light illumination. Because of the optical versatility and manufacturability of the proposed BDOEs, the reported spectrum-splitting approach provides a new approach toward low-cost solar power. PMID:25166805

  8. Research and Design Problems Introduced by Increased Power Output

    NASA Technical Reports Server (NTRS)

    Kurtz, Oskar

    1937-01-01

    In what follows the question of the number and geometrical arrangement of the cylinders so important in the design of high performance power units will be considered from various points of view. A discussion will be given of the possibilities of the various working processes and an investigation will be made of possible means for improving the continuous operation and take-off performance, particularly the methods of supercharging, increasing the r.p.m., and employing the two-stroke-cycle engine. Finally, the question of lowered fuel consumption will be gone over briefly. The subject will be treated under four headings: I) Considerations on the engine layout; II) Increase in output per given swept volume; III) Improvement in the take-off performance; IV) Lowering of the fuel consumption.

  9. 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.

  10. 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

  11. High-frequency multi-wavelength acoustic power maps

    NASA Astrophysics Data System (ADS)

    Hill, Frank; Ladenkov, Oleg; Ehgamberdiev, Shuhrat; Chou, Dean-Yi

    2001-01-01

    Acoustic power maps have been constructed using SOHO/MDI velocity and intensity data in Ni I 6768; NSO High-L Helioseismometer (HLH) Ca K intensity; and Taiwan Oscillation Network (TON) intensity in Ca K. The HLH data provides maps up to a frequency of 11.9 mHz, substantially higher than the usual 8.33 mHz. The Ca K observations show a surprising strong enhancement of power within a sunspot at all temporal frequencies, while the Ni I data show the well-known suppression of power. Tests suggest that this apparent acoustic enhancement is the result of strong intensity gradients observed through terrestrial seeing.

  12. Maximal muscle power output in cycling: a modelling approach.

    PubMed

    Yoshihuku, Y; Herzog, W

    1996-04-01

    This study sought to find the optimal design parameters for a bicycle-rider system (crank length, pelvic inclination, seat height and rate of crank rotation) that maximise the power output from muscles of the human lower limb during cycling. The human lower limb was modelled as a planar system of five rigid bodies connected by four frictionless pin joints and driven by seven functional muscle groups. The muscles were assumed to behave according to an adapted form of Hill's (1938) equation, incorporating the muscle force-length relation. The force-length relation and the values of length that served as input into the relations of the various muscles were defined in the following two ways: (1) the force-length relation was parabolic, based on the experiment of Woittiez et al. (1984), and the length was defined as the whole muscle length; and (2) the force-length relation was expressed as a combination of lines, based on the cross-bridge theory, and the length was defined as muscle fibre length. In the second definition, the joint configurations at which four of the seven muscle groups reached optimal length (i.e. the length at which the muscle can exert maximal isometric force) were further given in two ways. The first way was consistent with a previous study from this laboratory (Yoshihuku and Herzog, 1990); the second way relied on unpublished experimental data. The dependence of the average power on the design parameters and definitions of the force-length relation and muscle length was examined. Maximal average power for one full crank rotation with a crank length of 0.17 m was found to be about 1300 W for definition 1 and 1000 W for definition 2. The average power was more sensitive to changes in design parameters in definition 2 than definition 1. The optimal rate of crank rotation with a crank length of 0.17 m was 18.4 rad s-1 (176 rev min-1) for definition 1 (this value is different from the result of the previous study due to revisions in input for two

  13. 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

  14. 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.

  15. 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.

  16. 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

  17. Ultrasonic waveguide sensor for acoustic monitoring of nuclear power plants

    SciTech Connect

    Mel'nikov, V.I.; Khokhlov, V.N.; Duntsev, A.V.

    1988-02-01

    Waveguide sensors are being increasingly used for acoustic emission monitoring of equipment in nuclear power plants and in systems for acoustic diagnostics of the coolant. In this paper we examine the construction of a waveguide sensor for acoustic monitoring for the example of an impedance sensor for the steam content of water coolant, intended for use in the active emission-reception mode. The dynamic properties of the sensor are determined by the construction and the dimensions of the transducer, and are usually represented by its amplitude-frequency characteristic, which, as a rule, is of the resonance type. The longitudinal-wave waveguide, made from steel wire 0.8-1.2 mm in diameter, can transmit signals in the band 50-1000 kHz. To increase the reliability and the ease of maintenance of the monitoring system the transducer and the waveguide are connected in a detachable manner.

  18. 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.

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

    NASA Astrophysics Data System (ADS)

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

    2015-03-01

    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.

  20. 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.

  1. 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.

  2. 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.

  3. 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.

  4. 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.

  5. 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.

  6. 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.

  7. 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.

  8. Power output enhancement of a vibration-driven electret generator for wireless sensor applications

    NASA Astrophysics Data System (ADS)

    Masaki, Tatsuakira; Sakurai, Kenji; Yokoyama, Toru; Ikuta, Masayo; Sameshima, Hiroshi; Doi, Masashi; Seki, Tomonori; Oba, Masatoshi

    2011-10-01

    We developed a compact vibration-driven electret generator that excelled at a power output. It succeeded in the operation of wireless sensor modules only on electricity from electret generators. This electret generator can supply enough power to operate a wireless sensor module without an external power source. It was necessary for enabling this operation to enhance the power output of the electret generator. We enhanced the power output by decreasing the parasitic capacitance. To decrease the parasitic capacitance, we fabricated a collector substrate using concave electrodes. We decreased it from 25 to 17 pF. As a result, the power output from our generator was enhanced from 40 to 100 µW considerably at an acceleration of 0.15 g (1.47 m s-2) and a resonance frequency of 30 Hz.

  9. 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.

  10. 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.

  11. Relationship between acoustic power and acoustic radiation force on absorbing and reflecting targets for spherically focusing radiators.

    PubMed

    Gélat, Pierre; Shaw, Adam

    2015-03-01

    Total acoustic output power is an important parameter required by standards for most ultrasonic medical equipment including high-intensity focused ultrasound (HIFU) systems. Radiation force balances are routinely used; however, radiation force is not strictly dependent on the ultrasound power but, rather, on the wave momentum resolved in one direction. Consequently, measurements based on radiation force become progressively less accurate as the ultrasound wave deviates further from a true plane wave. HIFU transducers can be very strongly focused with F-numbers less than one: under these conditions, the uncertainty associated with use of the radiation force method becomes very significant. International Standards IEC 61161 and IEC 62555 suggest plane-wave correction factors for unfocused transducers radiating onto an ideal absorbing target and focusing corrections for focused transducers radiating onto ideal absorbing targets and onto conical reflecting targets (IEC 61161). Previous models have relied on calculations based on the Rayleigh integral, which is not strictly correct for curved sources. In the work described here, an approach combining finite element methods with a discretization of the Helmholtz equation was developed, making it possible to model the boundary condition at the structure/fluid interface more correctly. This has been used to calculate the relationship between radiation force and total power for both absorbing and conical reflecting targets for transducers ranging from planar to an F-number of 0.5 (hemispherical) and to compare with the recommendations of IEC 61161 and IEC 62555. PMID:25683223

  12. 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.

  13. 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.

  14. Highly efficient and high output power of erbium doped fiber laser in a linear cavity configuration

    NASA Astrophysics Data System (ADS)

    Awang, N. A.; Zulkifli, M. Z.; Norizan, S. F.; Harun, S. W.; Ghani, Z. A.; Ahmad, H.

    2010-10-01

    A simple Erbium Doped Fiber Laser (EDFL) in linear cavity configuration is reported. The cavity design is based on an FBG as a back reflector, and a loop back optical circulator with an output coupler as the front reflector. Different coupling ratios of the coupler are tested and 50: 50 provides the highest coupling output power of 22.06 dBm (160.7 mW). The pump power conversion efficiency is about 95% when pumping with two pump lasers at 1460 and 1490 nm with combined pumping power of 545 mW. The laser output has a measured linewidth of 0.0179 nm.

  15. Power scaling of bars toward 85mW per 1μm stripe width reliable output power

    NASA Astrophysics Data System (ADS)

    Krejci, Martin; Gilbert, Yvonne; Müller, Jürgen; Todt, René; Weiss, Stefan; Lichtenstein, Norbert

    2009-02-01

    The attractiveness of bars for industrial applications depends strongly on the reliable high brightness operation. For 9xx bars we report on high filling factor configurations with 200W reliable output power. Our low filling factor devices with output power between 40W and 90W have proven to operate reliably at output power densities of 85mW per 1µm stripe width, showing power wear-out degradation of less than 0.5% per 1000h operation time. For shorter wavelengths we present solutions for 808-880 nm bars. For our 808nm bars we observe power degradation of less than 4% after 8000h hard-pulse life test at 75W output power.

  16. Marginal Power Loss Extraction Method for Future High Output Power Density Converter

    NASA Astrophysics Data System (ADS)

    Takao, Kazuto; Adachi, Kazuhiro; Hayashi, Yusuke; Ohashi, Hiromichi

    Novel exact MOSFET switching loss analysis and formulation methods have been proposed for designing high output power density converters. To analyze influences of circuit stray parameters on MOSFET switching loss with experiments, a parameter adjustable circuit board has been fabricated. The circuit board has a function to vary circuit stray inductance and capacitance values like a circuit simulator. Correlations between MOSFET switching loss energies and circuit stray parameters are successfully analyzed with the circuit board. Based on the analysis results, switching loss energies are formulated with empirical equations to establish a exact power loss calculation tool for the converter design. Switching loss energies caused by semiconductor device parameters are modeled by a capacitance charge/discharge model. The procedure to formulate the switching loss energies with empirical equations is presented. Switching loss energies calculated with empirical equations are verified with measurements, and high accuracy of more than 95% has been achieved.

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

    PubMed

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

    2015-06-01

    Recent studies indicate that the utilization of the hexagonal barbell jump squat (HBJS) compared with the traditional barbell jump squat may offer a superior method of developing peak power. The notion that a single optimal load may be prescribed in training programs aiming to develop peak power is subject to debate. The purpose of this study was to identify the optimal load corresponding with peak power output during the HBJS in professional rugby union players. Seventeen professional rugby union players participated in this study. Participants performed 3 unloaded countermovement jumps on a force plate and 3 HBJS at each of the following randomized loads: 10, 20, 30, and 40% of box squat 1 repetition maximum (1RM). Peak power output was the dependent variable of interest. A one-way repeated measures analysis of variance was conducted to compare peak power output across each load. Peak power output was the dependent variable of interest. A significant main effect for load was observed (Wilk's Lambda = 0.11, F(4,13) = 18.07, p < 0.01, partial η2 = 0.88). Results of the Bonferroni-adjusted pairwise comparisons indicated that peak power output in the HBJS is optimized at a load range between 10 and 20% of box squat 1RM. The results of this study indicate that the use of the HBJS with a training load between 10 and 20% of box squat 1RM optimizes peak power output in professional rugby union players. PMID:25486301

  18. 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.

  19. 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.

  20. 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.

  1. 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.

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

    NASA Astrophysics Data System (ADS)

    Ueno, Toshiyuki

    2015-05-01

    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/cm3 under resonant vibration of 212 Hz and 1.2 G was obtained in miniature prototype using Fe-Ga rod of 2 × 0.5× 7 mm3. Furthermore, the damping effect was observed, which demonstrates high energy conversion of the generator.

  3. 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

  4. Output characteristics of high power cryogenic Yb:YAG TRAM laser oscillator.

    PubMed

    Furuse, Hiroaki; Kawanaka, Junji; Miyanaga, Noriaki; Chosrowjan, Haik; Fujita, Masayuki; Takeshita, Kenji; Izawa, Yasukazu

    2012-09-10

    We analyzed the output power characteristics of a cryogenically cooled Yb:YAG total-reflection active-mirror (TRAM) laser oscillator including the temperature dependence of the emission cross section and the reabsorption loss of the Yb:YAG TRAM. A CW multi-transverse mode oscillation of a 9.8 at.% doped 0.6 mm thick Yb:YAG ceramic TRAM was investigated for various pump spot sizes and compared with theoretical results. The Yb:YAG temperatures were inferred from the ratio between fluorescence intensities at 1022 nm and 1027 nm which varied significantly with temperature below 200 K. Output power calculations using evaluated temperatures were in good agreement with the experimental data measured between 77 and 200 K, and the output power suppression due to the temperature rise observed above ~140 K. To the best of our knowledge, this is the first evaluation of output power for a cryogenically cooled Yb:YAG TRAM laser. PMID:23037293

  5. Efficiencies of two-level weak dissipation quantum Carnot engines at the maximum power output

    NASA Astrophysics Data System (ADS)

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

    2013-04-01

    A weak-dissipation cycle model of two-level quantum Carnot engines is proposed by adopting a generic energy spectrum and the superposition effect of quantum systems. Expressions for the power output and efficiency of the cycle are derived. The optimal relation between the power output and the efficiency is obtained and the optimally operating region of the cycle is determined. Moreover, analytical expression for the efficiency of the cycle at the maximum power output is deduced and the lower and upper bounds of the efficiency at the maximum power output are given. The results obtained are general and can be directly used to discuss the optimal performance characteristics of several types of two-level quantum Carnot engines.

  6. Evaluation of human middle ear function via an acoustic power assessment.

    PubMed

    Allen, Jont B; Jeng, Patricia S; Levitt, Harry

    2005-01-01

    Measurements of middle ear (ME) acoustic power flow (power reflectance, power absorption, and transmittance) and normalized impedance (acoustic resistance, acoustic reactance, and impedance magnitude) were compared for their utility in clinical applications. Transmittance, a measure of the acoustic power absorbed by the ME, was found to have several important advantages over other measures of acoustic power flow. In addition to its simple and audiologically relevant physical interpretation (absorbed power), the normal transmittance curve has a simple shape that is visually similar to the ME transfer function. The acoustic impedance measures (resistance and reactance) provided important additional information about ME status and supplemented transmittance measurements. Together these measurements can help identify unusual conditions such as eardrum perforations. While this article is largely a review of the development of a commercial power reflectance measurement system, previously unpublished experimental results are presented. PMID:16470465

  7. Control strategies to optimise power output in heave buoy energy convertors

    NASA Astrophysics Data System (ADS)

    Abu Zarim, M. A. U. A.; Sharip, R. M.

    2013-12-01

    Wave energy converter (WEC) designs are always discussed in order to obtain an optimum design to generate the power from the wave. Output power from wave energy converter can be improved by controlling the oscillation in order to acquire the interaction between the WEC and the incident wave.The purpose of this research is to study the heave buoys in the interest to generate an optimum power output by optimising the phase control and amplitude in order to maximise the active power. In line with the real aims of this study which investigate the theory and function and hence optimise the power generation of heave buoys as renewable energy sources, the condition that influence the heave buoy must be understand in which to propose the control strategies that can be use to control parameters to obtain optimum power output. However, this research is in an early stage, and further analysis and technical development is require.

  8. 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

  9. 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.

  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. 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.

  12. Effects of loading and size on maximum power output and gait characteristics in geckos.

    PubMed

    Irschick, Duncan J; Vanhooydonck, Bieke; Herrel, Anthony; Andronescu, Anemone

    2003-11-01

    Stride length, stride frequency and power output are all factors influencing locomotor performance. Here, we first test whether mass-specific power output limits climbing performance in two species of geckos (Hemidactylus garnoti and Gekko gecko) by adding external loads to their bodies. We then test whether body size has a negative effect on mass-specific power output. Finally, we test whether loading affects kinematics in both gecko species. Lizards were induced to run vertically on a smooth wooden surface with loads of 0-200% of body mass (BM) in H. garnoti and 0-100% BM in G. gecko. For each stride, we calculated angular and linear kinematics (e.g. trunk angle, stride length), performance (maximum speed) and mean mass-specific power output per stride. The addition of increasingly large loads caused an initial increase in maximum mass-specific power output in both species, but for H. garnoti, mass-specific power output remained constant at higher loads (150% and 200% BM), even though maximum velocity declined. This result, in combination with the fact that stride frequency showed no evidence of leveling off as speed increased in either species, suggests that power limits maximum speed. In addition, the large gecko (G. gecko) produced significantly less power than the smaller H. garnoti, despite the fact that both species ran at similar speeds. This difference disappeared, however, when we recalculated power output based on higher maximum speeds for unloaded G. gecko moving vertically obtained by other researchers. Finally, the addition of external loads did not affect speed modulation in either species: both G. gecko and H. garnoti increase speed primarily by increasing stride frequency, regardless of loading condition. For a given speed, both species take shorter but more strides with heavier loads, but for a given load, G. gecko attains similar speeds to H. garnoti by taking longer but fewer strides. PMID:14555734

  13. A radioisotope-powered surface acoustic wave transponder

    NASA Astrophysics Data System (ADS)

    Tin, S.; Lal, A.

    2009-09-01

    We demonstrate a 63Ni radioisotope-powered pulse transponder that has a SAW (surface acoustic wave) device as the frequency transmission frequency selector. Because the frequency is determined by a SAW device, narrowband detection with an identical SAW device enables the possibility for a long-distance RF-link. The SAW transponders can be buried deep into structural constructs such as steel and concrete, where changing batteries or harvesting vibration or EM energy is not a reliable option. RF-released power to radioisotope- released power amplification is 108, even when regulatory safe amounts of 63Ni are used. Here we have achieved an 800 µW pulse (315 MHz, 10 µs pause) across a 50 Ω load every 3 min, using a 1.5 milli-Ci 63Ni source.

  14. 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

  15. 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.

  16. 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.

  17. A constant-load ergometer for measuring peak power output and fatigue.

    PubMed

    Williams, J H; Barnes, W S; Signorile, J F

    1988-11-01

    A constant-load cycle ergometer was constructed that allows maximal power output to be measured for each one-half pedal revolution during brief, high-intensity exercise. To determine frictional force, an electronic load cell was attached to the resistance strap and the ergometer frame. Dead weights were attached to the strap's free end. Flywheel velocity was recorded by means of a magnetic switch and two magnets placed on the pedal sprocket. Pedaling resulted in magnetically activated switch closures, which produced two electronic pulses per pedal revolution. Pulses and load cell output were recorded (512 Hz), digitized, and stored on disk via microcomputer. Power output was later computed for each pair of adjacent pulses, representing average power per one-half pedal revolution. Power curves generated for each subject were analyzed for peak power output (the highest one-half pedal revolution average), time to peak power, power fatigue rate and index, average power, and total work. Thirty-eight males performed two 15-s tests separated by 15 min (n = 16) or 48 h (n = 22). Peak power output ranged from 846.0 to 1,289.1 W. Intraclass correlation analysis revealed high test-retest reliability for all parameters recorded on the same or different days (R = 0.91-0.97). No significant differences (P greater than 0.05) were noted between parameter means of the first and second tests. These results indicate that the ergometer described provides a means for conveniently and reliably assessing short-term power output and fatigue. PMID:3209578

  18. 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

  19. Fiber laser pumped high power mid-infrared laser with picosecond pulse bunch output.

    PubMed

    Wei, Kaihua; Chen, Tao; Jiang, Peipei; Yang, Dingzhong; Wu, Bo; Shen, Yonghang

    2013-10-21

    We report a novel quasi-synchronously pumped PPMgLN-based high power mid-infrared (MIR) laser with picosecond pulse bunch output. The pump laser is a linearly polarized MOPA structured all fiberized Yb fiber laser with picosecond pulse bunch output. The output from a mode-locked seed fiber laser was directed to pass through a FBG reflector via a circulator to narrow the pulse duration from 800 ps to less than 50 ps and the spectral FWHM from 9 nm to 0.15 nm. The narrowed pulses were further directed to pass through a novel pulse multiplier through which each pulse was made to become a pulse bunch composing of 13 sub-pulses with pulse to pulse time interval of 1.26 ns. The pulses were then amplified via two stage Yb fiber amplifiers to obtain a linearly polarized high average power output up to 85 W, which were then directed to pass through an isolator and to pump a PPMgLN-based optical parametric oscillator via quasi-synchronization pump scheme for ps pulse bunch MIR output. High MIR output with average power up to 4 W was obtained at 3.45 micron showing the feasibility of such pump scheme for ps pulse bunch MIR output. PMID:24150378

  20. Stretch-induced enhancement of mechanical power output in human multijoint exercise with countermovement.

    PubMed

    Takarada, Y; Hirano, Y; Ishige, Y; Ishii, N

    1997-11-01

    The relation between the eccentric force developed during a countermovement and the mechanical power output was studied in squatting exercises under nominally isotonic load (50% of 1-repetition maximum). The subjects (n = 5) performed squatting exercises with a countermovement at varied deceleration rates before lifting the load. The ground reaction force and video images were recorded to obtain the power output of the body. Net muscle moments acting at hip, knee, and ankle joints were calculated from video recordings by using inverse dynamics. When an intense deceleration was taken at the end of downward movement, large eccentric force was developed, and the mechanical power subsequently produced during the lifting movement was consistently larger than that produced without the countermovement. Both maximal and mean power outputs during concentric actions increased initially with the eccentric force, whereas they began to decline when the eccentric force exceeded approximately 1.4 times the sum of load and body weight. Video-image analysis showed that this characteristic relation was predominantly determined by the torque around the knee joint. Electromyographic analyses showed no consistent increase in time-averaged integrated electromyograph from vastus lateralis with the power output, suggesting that the enhancement of power output is primarily caused by the prestretch-induced improvement of an intrinsic force-generating capability of the agonist muscle. PMID:9375347

  1. Estimation of Battery Capacity for Fluctuation Suppression of a PV Power Station Output

    NASA Astrophysics Data System (ADS)

    Akatsuka, Motoki; Hara, Ryoichi; Kita, Hiroyuki; Ito, Takamitsu; Ueda, Yoshinobu; Saito, Yutaka

    Some MW-class PV power stations are now under construction and more PV power stations will be introduced in future. However, the penetration of PV power station may disturb a stable operation of the power system. The largest concerns are frequency variation and voltage variation caused by fluctuation of PV power station output. When these variations can not be eliminated by the conventional system operation and control schemes, installation of energy storage system might be needed. From this background, the authors have developed control method of battery system for fluctuation suppression of PV power station output. In this paper, battery capacity needed to satisfy the required fluctuation suppression level is estimated. In the estimation, two types of suppression control schemes; one can save the required power capacity and another can save energy capacity.

  2. 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. PMID:26625058

  3. Effect of external signal on the output power of an oscillator with electron feedback

    NASA Astrophysics Data System (ADS)

    Frolov, N. S.; Koronovskii, A. A.; Hramov, A. E.

    2012-11-01

    The effect of an external single-frequency harmonic signal on the output power of an oscillator with electron feedback has been studied by analytical and numerical methods. It is established that an increase in the input signal power leads to sharp growth in the output power of the nonautonomous oscillator. Physical processes that take place in the electron beam with virtual cathode under the action of an external harmonic signal, which leads to velocity modulation in the electron beam entering the interaction space, have been analyzed. The obtained results well agree with the data of previous experimental investigations of the signal gain in a low-voltage vircator.

  4. 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.

  5. High Power Factor Control Regulating Inverter Output Power in IPM Motor Driven by Inverter System without Electrolytic Capacitor

    NASA Astrophysics Data System (ADS)

    Inazuma, Kazuya; Ohishi, Kiyoshi; Haga, Hitoshi; Sazawa, Mataki; Kondo, Seiji

    This paper presents a new high power factor control method for a single-to-three-phase power converter without an electrolytic capacitor. The circuit used in the method consists of a single-phase rectifier, a small film capacitor at DC-link, a voltage-source three-phase inverter, and an IPM motor. The inverter regulates both the velocity of the IPM motor and input current waveform. In order to obtain a power factor of unity, we propose a new control method that regulates the inverter output power. The inverter output power controller is placed between the speed controller and the q-axis current controller. The inverter power is regulated by a PI and repetitive controller. When repetitive control is applied to the inverter power controller, the phase delay of the inverter power controller is quite small. The superior performance of the proposed method is demonstrated by experimental results.

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

    PubMed

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

    2015-10-01

    We aimed to examine the reliability and validity of the peak power output test on a rowing ergometer (Concept II Model D Inc.) and to establish the "optimal resistance" at which this peak power output was observed in 87 participants with varying levels of physical activity and rowing expertise: 15 male and 12 female physically inactive students (age: 21 ± 2 years), 16 male and 20 female physically active students (age: 23 ± 2 years), and 15 male and 9 female trained rowers (age: 19 ± 2 years). The participants performed countermovement jump (CMJ) test on a force plate, followed by 3 maximal-effort rowing trials using the lowest, medium, and the highest adjustable resistance settings (i.e., "1", "5," and "10" on the resistance control dial on the ergometer) in randomized order. The test proved to be reliable (coefficients of variation: 2.6-6.5%; intraclass correlation coefficients: 0.87-0.98). The correlation coefficients between CMJ peak power and rowing peak power (both in watts per kilogram) were fairly consistent across all 3 groups of participants and resistance levels, ranging between r = 0.70 and r = 0.78. Finally, the highest power output was observed at the highest resistance setting in 2 nonathletic groups (p < 0.01), whereas rowers seem to produce the highest power output at the moderate-resistance setting. We conclude that the power output test on a Concept II rowing ergometer may serve as a reliable and valid tool for assessing whole-body peak power output in untrained individuals and rowing athletes. PMID:25785705

  7. 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.

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

    PubMed

    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. PMID:24985809

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

    SciTech Connect

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

    2014-06-15

    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.

  10. 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.

  11. Enhanced channel estimation and symbol detection for high speed multi-input multi-output underwater acoustic communications.

    PubMed

    Ling, Jun; Yardibi, Tarik; Su, Xiang; He, Hao; Li, Jian

    2009-05-01

    The need for achieving higher data rates in underwater acoustic communications leverages the use of multi-input multi-output (MIMO) schemes. In this paper two key issues regarding the design of a MIMO communications system, namely, channel estimation and symbol detection, are addressed. To enhance channel estimation performance, a cyclic approach for designing training sequences and a channel estimation algorithm called the iterative adaptive approach (IAA) are presented. Sparse channel estimates can be obtained by combining IAA with the Bayesian information criterion (BIC). Moreover, the RELAX algorithm can be used to improve the IAA with BIC estimates further. Regarding symbol detection, a 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. Both simulated and experimental results are provided to validate the proposed MIMO scheme. RACE'08 experimental results employing a 4 x 24 MIMO system show that the proposed scheme enjoys an average uncoded bit error rate of 0.38% at a payload data rate of 31.25 kbps and an average coded bit error rate of 0% at a payload data rate of 15.63 kbps. PMID:19425650

  12. Increasing output power of an 850 MHz tetrode with a floating-deck modulator

    SciTech Connect

    Rees, D.; Friedrichs, C.

    1990-01-01

    Designers of high-power amplifiers generally regard the region above 300 MHz as a domain dominated by velocity-modulated (klystron/TWT) devices. However, as the power requirements diminish, there are attractive alternatives. The high-power 850-MHz requirements of the ground test accelerator (GTA) program can be filled by 1-MW klystrons, but it would be more efficient to use a lower-power device for a 50-kW requirement. To meet the 850-MHz medium-power requirements, Los Alamos National Laboratory is developing an 850-MHz tetrode amplifier. These amplifiers will provide rf power to the momentum compactor and bunch rotator cavities of the GTA. Available tubes provide only a limited safety margin for a low-risk design at the power levels and duty factor required for GTA cavities. At 850 MHz, the output power capability of available tubes is reduced because of transit time effects and limited anode voltage holdoff. Pulsing the anode of the output tetrode amplifier will allow higher output power with minimum design risk. A floating-deck modulator acts as a high-voltage/high-current switch, so voltage is applied to the anode of the gridded tube only during the rf pulse. The anode voltage holdoff capability of the tube is substantially enhanced by operating in this mode. This paper will describe the design of the floating deck modulator and its impact on the design risk of the 850-MHz tetrode amplifier.

  13. 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

  14. 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.

  15. A dual mode charge pump with adaptive output used in a class G audio power amplifier

    NASA Astrophysics Data System (ADS)

    Yong, Feng; Zhenfei, Peng; Shanshan, Yang; Zhiliang, Hong; Yang, Liu

    2011-04-01

    A dual mode charge pump to produce an adaptive power supply for a class G audio power amplifier is presented. According to the amplitude of the input signals, the charge pump has two level output voltage rails available to save power. It operates both in current mode at high output load and in pulse frequency modulation (PFM) at light load to reduce the power dissipation. Also, dynamic adjustment of the power stage transistor size based on load current at the PFM mode is introduced to reduce the output voltage ripple and prevent the switching frequency from audio range. The prototype is implemented in 0.18 μm 3.3 V CMOS technology. Experimental results show that the maximum power efficiency of the charge pump is 79.5% @ 0.5x mode and 83.6% @ 1x mode. The output voltage ripple is less than 15 mV while providing 120 mA of the load current at PFM control and less than 18 mV while providing 300 mA of the load current at current mode control. An analytical model for ripple voltage and efficiency calculation of the proposed PFM control demonstrates reasonable agreement with measured results.

  16. 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.

  17. Output Control Technologies for a Large-scale PV System Considering Impacts on a Power Grid

    NASA Astrophysics Data System (ADS)

    Kuwayama, Akira

    The mega-solar demonstration project named “Verification of Grid Stabilization with Large-scale PV Power Generation systems” had been completed in March 2011 at Wakkanai, the northernmost city of Japan. The major objectives of this project were to evaluate adverse impacts of large-scale PV power generation systems connected to the power grid and develop output control technologies with integrated battery storage system. This paper describes the outline and results of this project. These results show the effectiveness of battery storage system and also proposed output control methods for a large-scale PV system to ensure stable operation of power grids. NEDO, New Energy and Industrial Technology Development Organization of Japan conducted this project and HEPCO, Hokkaido Electric Power Co., Inc managed the overall project.

  18. 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.}

  19. Dependence of Output Power on Slot Antenna Width in Terahertz Oscillating Resonant Tunneling Diodes

    NASA Astrophysics Data System (ADS)

    Shibayama, Hirotaka; Shiraishi, Masato; Suzuki, Safumi; Asada, Masahiro

    2012-05-01

    We report on the dependence of the output power on the slot antenna width in resonant tunneling diode (RTD) oscillators. The oscillators have different antenna widths of 4, 8, and 20 μm and the same antenna length of 130 μm. Although the experimentally observed oscillation frequencies were ~500 GHz and independent of the antenna width, maximized output powers of ~130 μW were obtained at the antenna width of 8 μm by the impedance matching between the RTD and the antenna.

  20. High-output-power deep ultraviolet light-emitting diode assembly using direct bonding

    NASA Astrophysics Data System (ADS)

    Ichikawa, Masatsugu; Fujioka, Akira; Kosugi, Takao; Endo, Shinya; Sagawa, Harunobu; Tamaki, Hiroto; Mukai, Takashi; Uomoto, Miyuki; Shimatsu, Takehito

    2016-07-01

    We fabricated high-output-power 255 and 280 nm light-emitting diodes (LEDs) using direct bonding. The LED chips were bonded to sapphire lenses at room temperature using either atomic diffusion bonding or surface-activated bonding. The LEDs with lenses had a higher light extraction efficiency than conventionally structured LEDs. As a result, at a forward current of 350 mA, the output power of the 255 nm LED increased by a factor of 2.8, reaching 73.6 mW, while that of the 280 nm LED increased by a factor of 2.3, reaching 153 mW.

  1. 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

  2. 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.

  3. 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.

  4. 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.

  5. 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

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

    PubMed

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

    2016-05-20

    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. PMID:27053597

  7. Phosphorylation-dependent power output of transgenic flies: an integrated study.

    PubMed

    Dickinson, M H; Hyatt, C J; Lehmann, F O; Moore, J R; Reedy, M C; Simcox, A; Tohtong, R; Vigoreaux, J O; Yamashita, H; Maughan, D W

    1997-12-01

    We examine how the structure and function of indirect flight muscle (IFM) and the entire flight system of Drosophila melanogaster are affected by phosphorylation of the myosin regulatory light chain (MLC2). This integrated study uses site-directed mutagenesis to examine the relationship between removal of the myosin light chain kinase (MLCK) phosphorylation site, in vivo function of the flight system (flight tests, wing kinematics, metabolism, power output), isolated IFM fiber mechanics, MLC2 isoform pattern, and sarcomeric ultrastructure. The MLC2 mutants exhibit graded impairment of flight ability that correlates with a reduction in both IFM and flight system power output and a reduction in the constitutive level of MLC2 phosphorylation. The MLC2 mutants have wild-type IFM sarcomere and cross-bridge structures, ruling out obvious changes in the ultrastructure as the cause of the reduced performance. We describe a viscoelastic model of cross-bridge dynamics based on sinusoidal length perturbation analysis (Nyquist plots) of skinned IFM fibers. The sinusoidal analysis suggests the high power output of Drosophila IFM required for flight results from a phosphorylation-dependent recruitment of power-generating cross-bridges rather than a change in kinetics of the power generating step. The reduction in cross-bridge number appears to affect the way mutant flies generate flight forces of sufficient magnitude to keep them airborne. In two MLC2 mutant strains that exhibit a reduced IFM power output, flies appear to compensate by lowering wingbeat frequency and by elevating wingstroke amplitude (and presumably muscle strain). This behavioral alteration is not seen in another mutant strain in which the power output and estimated number of recruited cross-bridges is similar to that of wild type. PMID:9414224

  8. Phosphorylation-dependent power output of transgenic flies: an integrated study.

    PubMed Central

    Dickinson, M H; Hyatt, C J; Lehmann, F O; Moore, J R; Reedy, M C; Simcox, A; Tohtong, R; Vigoreaux, J O; Yamashita, H; Maughan, D W

    1997-01-01

    We examine how the structure and function of indirect flight muscle (IFM) and the entire flight system of Drosophila melanogaster are affected by phosphorylation of the myosin regulatory light chain (MLC2). This integrated study uses site-directed mutagenesis to examine the relationship between removal of the myosin light chain kinase (MLCK) phosphorylation site, in vivo function of the flight system (flight tests, wing kinematics, metabolism, power output), isolated IFM fiber mechanics, MLC2 isoform pattern, and sarcomeric ultrastructure. The MLC2 mutants exhibit graded impairment of flight ability that correlates with a reduction in both IFM and flight system power output and a reduction in the constitutive level of MLC2 phosphorylation. The MLC2 mutants have wild-type IFM sarcomere and cross-bridge structures, ruling out obvious changes in the ultrastructure as the cause of the reduced performance. We describe a viscoelastic model of cross-bridge dynamics based on sinusoidal length perturbation analysis (Nyquist plots) of skinned IFM fibers. The sinusoidal analysis suggests the high power output of Drosophila IFM required for flight results from a phosphorylation-dependent recruitment of power-generating cross-bridges rather than a change in kinetics of the power generating step. The reduction in cross-bridge number appears to affect the way mutant flies generate flight forces of sufficient magnitude to keep them airborne. In two MLC2 mutant strains that exhibit a reduced IFM power output, flies appear to compensate by lowering wingbeat frequency and by elevating wingstroke amplitude (and presumably muscle strain). This behavioral alteration is not seen in another mutant strain in which the power output and estimated number of recruited cross-bridges is similar to that of wild type. Images FIGURE 1 FIGURE 2 PMID:9414224

  9. A modified Hill muscle model that predicts muscle power output and efficiency during sinusoidal length changes.

    PubMed

    Lichtwark, G A; Wilson, A M

    2005-08-01

    The power output of a muscle and its efficiency vary widely under different activation conditions. This is partially due to the complex interaction between the contractile component of a muscle and the serial elasticity. We investigated the relationship between power output and efficiency of muscle by developing a model to predict the power output and efficiency of muscles under varying activation conditions during cyclical length changes. A comparison to experimental data from two different muscle types suggests that the model can effectively predict the time course of force and mechanical energetic output of muscle for a wide range of contraction conditions, particularly during activation of the muscle. With fixed activation properties, discrepancies in the work output between the model and the experimental results were greatest at the faster and slower cycle frequencies than that for which the model was optimised. Further optimisation of the activation properties across each individual cycle frequency examined demonstrated that a change in the relationship between the concentration of the activator (Ca2+) and the activation level could account for these discrepancies. The variation in activation properties with speed provides evidence for the phenomenon of shortening deactivation, whereby at higher speeds of contraction the muscle deactivates at a faster rate. The results of this study demonstrate that predictions about the mechanics and energetics of muscle are possible when sufficient information is known about the specific muscle. PMID:16043588

  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. 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.

  12. 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.

  13. 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.

  14. 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.

  15. High-power output of ytterbium-doped oxyorthosilicate lasers at 1018 nm

    NASA Astrophysics Data System (ADS)

    Lin, Niannian; Li, Wenxue; Zhou, Yuan; Shi, Yi; Yan, Ming; Yang, Kangwen; Zhao, Jian; Yang, Xianghui; Zeng, Heping

    2013-01-01

    A high-power laser system at 1018 nm was realized with an ytterbium-doped oxyorthosilicate solid-state master oscillator and ytterbium-doped double-clad fiber amplifier. In the Yb:LSO (Yb:Lu2SiO5) and Yb:LYSO (Yb:LuYSiO5) master laser oscillator, we attained the broadest tunable wavelength range from 994.50 to 1094.22 nm. In the power amplifier, we achieved an output power up to 4.14 W at 1018 nm by amplifying the Yb:LSO laser under a pump power of 15.8 W.

  16. 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.

  17. 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.

  18. 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.

  19. 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

  20. 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.

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

    NASA Astrophysics Data System (ADS)

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

    2016-02-01

    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.

  2. Optimum operation of irreversible Carnot heat engines of finite size at maximum power output

    SciTech Connect

    Oezkaynak, S.

    1996-04-01

    In this article the author considers the optimum performance at the maximum power output of internally and externally irreversible heat engines of finite size in which heat transfer is proportional to the difference of temperature to an n-power. For the case n = 1, where heat transfer is Newtonian heat conduction, the hot-end/cold-end heat-exchanger size ratio is less than unity. For the case n = 4, which corresponds to radiative heat transfer, the values of design parameters are obtained from the numerical solution of two coupled nonlinear equations. For a radiative heat engine of finite size, the upper limit to the optimum efficiency at maximum power output is found to be 0.339.

  3. Synchronous power output fluctuations for an experimental open-cycle OTEC plant

    SciTech Connect

    Nihous, G.C.

    1997-12-01

    A 210 kW experimental Open-Cycle Ocean Thermal Energy Conversion plant was completed in Hawaii in 1993, and equipped with a synchronous generator to test its connection to the local power grid. During shakedown tests, large power output fluctuations were observed. Linear mathematical models of the system were developed, and numerical simulations reproduced observations well, for a given line frequency input, confirming in particular the resonant nature of a massive turbine rigidly connected to a small generator. The frequency-domain algorithm was extended to analyze the effect of inserting a fluid coupler between the turbine and the generator to eliminate large power output fluctuations. The actual installation of a fluid coupler in early 1994 allowed a validation of the model predictions.

  4. Pulse-width modulated external resistance increases the microbial fuel cell power output.

    PubMed

    Coronado, J; Perrier, M; Tartakovsky, B

    2013-11-01

    This study describes MFC operation with a pulse-width modulated connection of the external resistor (R-PWM mode) at low and high frequencies. Analysis of the output voltage profiles acquired during R-PWM tests showed the presence of slow and fast dynamic components, which can be described by a simple equivalent circuit model suitable for process control applications. At operating frequencies above 100 Hz a noticeable improvement in MFC performance was observed with the power output increase of 22-43% as compared to MFC operation with a constant external resistance. PMID:23989037

  5. 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.

  6. 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

  7. 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.

  8. 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.

  9. Efficiency at Maximum Power Output of a Quantum-Mechanical Brayton Cycle

    NASA Astrophysics Data System (ADS)

    Yuan, Yuan; He, Ji-Zhou; Gao, Yong; Wang, Jian-Hui

    2014-03-01

    The performance in finite time of a quantum-mechanical Brayton engine cycle is discussed, without introduction of temperature. The engine model consists of two quantum isoenergetic and two quantum isobaric processes, and works with a single particle in a harmonic trap. Directly employing the finite-time thermodynamics, the efficiency at maximum power output is determined. Extending the harmonic trap to a power-law trap, we find that the efficiency at maximum power is independent of any parameter involved in the model, but depends on the confinement of the trapping potential.

  10. 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

  11. 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.

  12. 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.

  13. 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.

  14. High output power reluctance electric motors with bulk high-temperature superconductor elements

    NASA Astrophysics Data System (ADS)

    Kovalev, L. K.; Ilushin, K. V.; Penkin, V. T.; Kovalev, K. L.; Larionoff, A. E.; M-A Koneev, S.; Modestov, K. A.; Larionoff, S. A.; Poltavets, V. N.; Akimov, I. I.; Alexandrov, V. V.; Gawalek, W.; Oswald, B.; Krabbes, G.

    2002-05-01

    We present new types of electric machines with the rotors containing bulk high-temperature superconductor (HTS) - YBCO and Bi-Ag - elements. We discuss different schematics of hysteresis, reluctance, 'trapped field' and composed synchronous HTS machines. The two-dimensional mathematical models describing the processes in such types of HTS machines were developed on the basis of the theoretical analysis of the electrodynamic and hysteresis processes in the single-domain and polycrystal YBCO ceramic samples and plate shape Bi-Ag elements. We give the test results of the series of hysteresis, reluctance, 'trapped field' and composed with permanent magnets HTS motors with an output power rating of 0.1-18 kW and current frequencies 50 Hz and 400 Hz. These results show that in the media of liquid nitrogen the specific output power per one unit weight of the HTS motor is four to seven times better than for conventional electric machines. A comparison of the theoretical and experimental characteristics of the developed HTS motors show that they are in good agreement. We discuss the test results for a liquid nitrogen cryogenic pump system with a hysteresis 500 W HTS motor. We describe several designs of new HTS motors operating in the media of liquid nitrogen with an output power 125 kW (and more) and a power factor of more than 0.8. We discuss future applications of new types of HTS motors for aerospace technology, on-land industry and transport systems.

  15. Ultra-low output impedance RF power amplifier for parallel excitation.

    PubMed

    Chu, Xu; Yang, Xing; Liu, Yunfeng; Sabate, Juan; Zhu, Yudong

    2009-04-01

    Inductive coupling between coil elements of a transmit array is one of the key challenges faced by parallel RF transmission. An ultra-low output impedance RF power amplifier (PA) concept was introduced to address this challenge. In an example implementation, an output-matching network was designed to transform the drain-source impedance of the metallic oxide semiconductor field effect transistor (MOSFET) into a very low value for suppressing interelement coupling effect, and meanwhile, to match the input impedance of the coil to the optimum load of the MOSFET for maximizing the available output power. Two prototype amplifiers with 500-W output rating were developed accordingly, and were further evaluated with a transmit array in phantom experiments. Compared to the conventional 50-Omega sources, the new approach exhibited considerable effectiveness suppressing the effects of interelement coupling. The experiments further indicated that the isolation performance was comparable to that achieved by optimized overlap decoupling. The new approach, benefiting from a distinctive current-source characteristic, also exhibited a superior robustness against load variation. Feasibility of the new approach in high-field MR was demonstrated on a 3T clinical scanner. PMID:19189287

  16. 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.

  17. Acoustics

    NASA Astrophysics Data System (ADS)

    The acoustics research activities of the DLR fluid-mechanics department (Forschungsbereich Stroemungsmechanik) during 1988 are surveyed and illustrated with extensive diagrams, drawings, graphs, and photographs. Particular attention is given to studies of helicopter rotor noise (high-speed impulsive noise, blade/vortex interaction noise, and main/tail-rotor interaction noise), propeller noise (temperature, angle-of-attack, and nonuniform-flow effects), noise certification, and industrial acoustics (road-vehicle flow noise and airport noise-control installations).

  18. 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.

  19. 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.

  20. Electrostatic Energy Harvester Utilizing High Density of Electrode for Higher Output Power

    NASA Astrophysics Data System (ADS)

    Minami, K.; Miwatani, N.; Kanda, K.; Fujita, T.; Maenaka, K.

    2015-12-01

    In this study, we report an improvement of output power from an electret type vibration energy harvester. Typical crossing-area change harvester has a stripe-shaped electret and counter electrode for making the capacitance change. In order to improve space efficiency, the counter electrodes are divided and arraignment with the same pitch of the electret. We investigate that adjoining the counter electrodes, the fringing effect is decreased and the capacitance change between the electrodes is larger than the conventional design from FEM analysis. The output power of 2.5 μW and 5.3 μW are obtained in each kind of counter electrode with the applied acceleration of 3 G at 350 Hz, which is about 2 or 4 times as high as our previous work.

  1. High-efficiency tunable yellow-orange VECSEL with an output power of 20 W

    NASA Astrophysics Data System (ADS)

    Kantola, Emmi; Leinonen, Tomi; Ranta, Sanna; Tavast, Miki; Guina, Mircea

    2014-03-01

    We report on the development of a high-efficiency frequency doubled vertical-external-cavity surface-emitting laser with an output power of 20 W and emission spectrum centered at 588 nm. The MBE-grown gain chip incorporated 10 GaInAs quantum wells and emitted in the 1180 nm range. The frequency conversion was achieved using a lithium triborate nonlinear crystal in an intra-cavity configuration. In addition to the nonlinear crystal, the V-shaped cavity also included a birefringent filter and an etalon for linewidth narrowing and wavelength tuning. The maximum optical-to-optical conversion efficiency obtained was ~28 % for 16 W of output power and the VECSEL had a tuning bandwidth of ~26 nm ranging from about 576 to 602 nm. We were also able to generate yellow pulses down to 570 ns duration by directly modulating the VECSEL's pump laser.

  2. Blue resonant-cavity light-emitting diode with half milliwatt output power

    NASA Astrophysics Data System (ADS)

    Yeh, Pinghui S.; Chang, Chi-Chieh; Chen, Yu-Ting; Lin, Da-Wei; Wu, Chun Chia; He, Jhao Hang; Kuo, Hao-Chung

    2016-03-01

    GaN-based resonant-cavity light-emitting diode (RCLED) has a circular output beam with superior directionality than conventional LED and has power scalability by using two-dimensional-array layout. In this work, blue RCLEDs with a top reflector of approximately 50% reflectance were fabricated and characterized. An output power of more than 0.5 mW per diode was achieved before packaging under room-temperature continuous-wave (CW) operation. The full width at half maximum (FWHM) of the emission spectrum was approximately 3.5 and 4.5 nm for 10- and 20-μm-diameter devices, respectively. And the peak wavelength as well as the FWHM remained stable at various currents and temperatures.

  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. Pre-exposure to hyperoxic air does not enhance power output during subsequent sprint cycling.

    PubMed

    Sperlich, Billy; Schiffer, Thorsten; Achtzehn, Silvia; Mester, Joachim; Holmberg, Hans-Christer

    2010-09-01

    Previous studies have indicated that aerobic pathways contribute to 13-27% of the energy consumed during short-term (10-20 s) sprinting exercise. Accordingly, the present investigation was designed to test the hypothesis that prior breathing of oxygen-enriched air (F(in)O(2) = 60%) would enhance power output and reduce fatigue during subsequent sprint cycling. Ten well-trained male cyclists (mean +/- SD age, 25 +/- 3 years; height, 186.1 +/- 6.9 cm; body mass, 79.1 +/- 8.2 kg; maximal oxygen uptake [VO(2max)]: 63.2 +/- 5.2 ml kg(-1) min(-1)) took 25 breaths of either hyperoxic (HO) or normoxic (NO) air before performing 15 s of cycling at maximal exertion. During this performance, the maximal and mean power outputs were recorded. The concentration of lactate, pH, partial pressure of and saturation by oxygen, [H(+)] and base excess in arterial blood were assessed before and after the sprint. The maximal (1,053 +/- 141 for HO vs. 1,052 +/- 165 W for NO; P = 0.77) and mean power outputs (873 +/- 123 vs. 876 +/- 147 W; P = 0.68) did not differ between the two conditions. The partial pressure of oxygen was approximately 2.3-fold higher after inhaling HO in comparison to NO, while lactate concentration, pH, [H(+)] and base excess (best P = 0.32) after sprinting were not influenced by exposure to HO. These findings demonstrate that the peak and mean power outputs of athletes performing short-term intense exercise cannot be improved by pre-exposure to oxygen-enriched air. PMID:20473681

  5. 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)). PMID:22400532

  6. Development of a multipactor discharge in the output channel of a powerful pulsed gyroklystron

    NASA Astrophysics Data System (ADS)

    Gvozdev, A. K.; Zharova, N. A.; Zaitsev, N. I.; Semenov, V. E.; Sorokin, A. A.

    2012-10-01

    Reasons for microwave discharge initiation in the vacuum section of the output waveguide of a powerful gyroklystron are discussed. It is found that the discharge is located near the range of an electron cyclotron resonance. A one-sided multipactor discharge is numerically simulated in wide ranges of tilt angles and permanent magnetic fields. It is shown that the cyclotron resonance may considerably lower the multipactor discharge threshold in contrast to earlier concepts.

  7. Buffer gas effects on output power of a copper vapor laser

    NASA Astrophysics Data System (ADS)

    Behrouzinia, S.; Khorasani, K.; Farahmandjou, M.

    2016-05-01

    A copper vapor laser with an active medium length of 60 cm and bore of 16 mm was operated and optimized using different buffer gases to investigate the effect of pressure and gas flow rates on the laser output power. It was shown that a special interval of operational pressure and an optimum gas flow rate associated with the type of buffer gas were obtained.

  8. Power Output Prediction From Jump Height and Body Mass Does Not Appropriately Categorize or Rank Athletes.

    PubMed

    Ache-Dias, Jonathan; Dal Pupo, Juliano; Gheller, Rodrigo G; Külkamp, Wladymir; Moro, Antônio R P

    2016-03-01

    The purposes of this study were (a) to verify the agreement of categorization and ranks based on the actual power output measured by a force plate (PPact) and the estimated power output (PPest) from jump height and body mass (BM), and (b) to verify whether the ratio standard is adequate to scale the PPact for BM. The countermovement jumps of 309 male athletes were analyzed. The athletes were first categorized into tertiles (superior, intermediate, and inferior) according to PPact and PPest. After that the athletes were ranked (highest to lowest power output) according to PPact and PPest. The PPest equation explained 81% of PPact variance (standard error of estimate = 277.4 W). The PPest (3,757.1 ± 579.8 W) displayed similar mean values compared with PPact (3,757.1 ± 642.3 W). However, the agreement between the categories generated by PPact and PPest was only moderate (k = 0.6; p < 0.01), and in the intermediate tertile, the categorization differs 38.8%. The agreement between the ranks analyzed from a Bland-Altman plot shows bias zero, but a wide limits of agreement (81 ranks; 26.2%). For the PPact scaling, the ratio standard may be considered as an adequate method for removing the BM effect, considering the lack of correlation between the scaled PPact (PPact/BM) and BM, and also the confirmation of Tanner's special circumstance. In conclusion, our findings indicate that the athlete's power output was not appropriately categorized or ranked when using PPest. Furthermore, the use of the scaled PPact is recommended to fairly compare athletes with different BMs. PMID:26332774

  9. Bismuth-doped germanosilicate fibre laser with 20-W output power at 1460 nm

    SciTech Connect

    Firstov, Sergei V; Shubin, Aleksei V; Khopin, V F; Mel'kumov, Mikhail A; Bufetov, Igor' A; Medvedkov, O I; Gur'yanov, Aleksei N; Dianov, Evgenii M

    2011-07-31

    We report the first cw bismuth - germanium codoped silica fibre laser with an output power above 20 W at 1460 nm and 50% optical efficiency. The laser operates on a transition between energy levels of bismuth-related active centres associated with silicon. The incorporation of a small amount ({approx}5 mol %) of germanium into the core of bismuth-doped silica fibre has little effect on its luminescence spectrum but reduces optical losses, which limit the laser efficiency. (letters)

  10. 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.

  11. 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. PMID:22154401

  12. Force, work and power output of lower limb muscles during human maximal-effort countermovement jumping.

    PubMed

    Nagano, Akinori; Komura, Taku; Fukashiro, Senshi; Himeno, Ryutaro

    2005-08-01

    The purpose of this study was to simulate human maximal-effort countermovement jumping with a three-dimensional neuromusculoskeletal model. The specific aim was to investigate muscle force, work and power output of major lower limb muscles during the motion. A neuromusculoskeletal model that has nine rigid body segments, 20 degrees of freedom, 32 Hill-type lower limb muscles was developed. The neural activation input signal was represented by a series of step functions with step duration of 0.05 s. The excitation-contraction dynamics of the contractile element, the tissues around the joints to limit the joint range of motion, as well as the foot-ground interaction were implemented. A simulation was started from a standing posture. Optimal pattern of the activation input signal was searched through numerical optimization with a goal of maximizing the height reached by the mass center of body after jumping up. As a result, feasible kinematics, ground reaction force profile and muscle excitation profile were generated. It was found that monoarticular muscles had major contributions of mechanical work and power output, whereas biarticular muscles had minor contributions. Hip adductors, abductors and external rotator muscles were vigorously activated, although their mechanical work and power output was minor because of their limited length change during the motion. Joint flexor muscles such as m. iliopsoas, m. biceps femoris short head and m. tibialis anterior were activated in the beginning of the motion with an effect of facilitating the generation of a countermovement. PMID:15811607

  13. High output power AlN vibration-driven energy harvesters

    NASA Astrophysics Data System (ADS)

    Cao, Z.; He, J.; Wang, Q.; Hara, M.; Oguchi, H.; Kuwano, H.

    2013-12-01

    This paper presents miniature AlN harvesters for harvesting low-frequency and two-dimensional vibration energy. A high fracture toughness and high yield strength stainless steel substrate was used to enhance output power and reduce resonate frequency of vibration energy harvesters. The thickness of 1.89 μm AlN films were deposited on 50 μm thick stainless steel (SUS) substrates for fabricating the harvesters. The Al/AlN/SUS multi-layer sheet was made into long and thin plate-like cantilevers with heavy proof masses attached at their free ends. The devices can collect vibration energy efficiently not only under perpendicular direction to the plate surface of cantilevers but also under the parallel direction. When vibration acceleration was 1.0 g, output power was 28.114 μW for perpendicular vibration and 51.735 μW for parallel vibration. When the acceleration of parallel vibration was 1.6 g, output power was 89.339 μW.

  14. Output microwave radiation power of low-voltage vircator with external inhomogeneous magnetic field

    NASA Astrophysics Data System (ADS)

    Kurkin, S. A.; Koronovskii, A. A.; Hramov, A. E.

    2011-04-01

    Dependence of the power of a broadband microwave radiation generated by a low-voltage oscillator with virtual cathode (vircator) on the parameters of an external inhomogeneous magnetic field has been studied by numerical simulations using a two-dimensional model. It is established that there are optimum parameters of the generator (configuration of the external magnetic field, electron beam current) for which the output radiation power is maximum. A relationship between the optimum conditions of virtual cathode formation in the electron beam and the microwave generation regime is established.

  15. The effect of an external signal on output microwave power of a low-voltage vircator

    NASA Astrophysics Data System (ADS)

    Phrolov, N. S.; Koronovskii, A. A.; Kalinin, Yu. A.; Kurkin, S. A.; Starodubov, A. V.; Hramov, A. E.

    2014-06-01

    This Letter is devoted to results of the both experimental and theoretical studies of electromagnetic radiation output power gain in the low-voltage microwave generator with a virtual cathode (vircator) under an external harmonic signal leading to the preliminary velocity modulation of the electron beam. The simple theoretical model of the electron beam with virtual cathode in a diode gap with retarding field under the external signal has been developed. The theoretical and numerical analysis have shown the possibility of power amplification in the vircator under the external influence. Obtained results of the theoretical consideration are proven by the experimental study.

  16. 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.

  17. 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

  18. Multiple solutions and corresponding power output of a nonlinear bistable piezoelectric energy harvester

    NASA Astrophysics Data System (ADS)

    Syta, Arkadiusz; Litak, Grzegorz; Friswell, Michael I.; Adhikari, Sondipon

    2016-04-01

    We examine multiple responses of a vibrational energy harvester composed of a vertical beam and a tip mass. The beam is excited horizontally by a harmonic inertial force while mechanical vibrational energy is converted to electrical power through a piezoelectric patch. The mechanical resonator can be described by single or double well potentials depending on the gravity force from the tip mass. By changing the tip mass we examine the appearance of various solutions and their basins of attraction. Identification of particular solutions of the energy harvester is important as each solution may provide a different level of power output.

  19. Increasing single mode power of 1.3-μm VCSELs by output coupling optimization.

    PubMed

    Mereuta, A; Caliman, A; Sirbu, A; Iakovlev, V; Mickovic, Z; Suruceanu, G; Kapon, E

    2015-05-01

    We report on the single mode emission power enhancement of 1.3-μm VCSELs by adjusting the reflectivity of the top GaAs-based DBR for output coupling optimization using selective removal of Bragg reflector layers. Devices with record single mode power of 6.8-mW at room temperature and 2.8-mW at 80°C, with more than 30 dB single mode suppression ratio, have been obtained. PMID:25969185

  20. Synchronously pumped optical parametric oscillation in periodically poled lithium niobate with 1-w average output power.

    PubMed

    Graf, T; McConnell, G; Ferguson, A I; Bente, E; Burns, D; Dawson, M D

    1999-05-20

    We report on a rugged all-solid-state laser source of near-IR radiation in the range of 1461-1601 nm based on a high-power Nd:YVO(4) laser that is mode locked by a semiconductor saturable Bragg reflector as the pump source of a synchronously pumped optical parametric oscillator with a periodically poled lithium niobate crystal. The system produces 34-ps pulses with a high repetition rate of 235 MHz and an average output power of 1 W. The relatively long pulses lead to wide cavity detuning tolerances. The comparatively narrow spectral bandwidth of <15 GHz is suitable for applications such as pollutant detection. PMID:18319928

  1. Transverse amplified spontaneous emission: The limiting factor for output energy of ultra-high power lasers

    NASA Astrophysics Data System (ADS)

    Chvykov, Vladimir; Nees, John; Krushelnick, Karl

    2014-02-01

    For the new generation of the ultra-high power lasers with tens of PW of output power, kJ-level energies have to be reached. Our modeling, applied to Ti:sapphire amplifiers, demonstrates for the first time, according our knowledge, that Transverse Amplified Spontaneous Emission (TASE) places an additional restriction on storing and extracting energy in larger gain apertures, even stronger than transverse parasitic generation (TPG). Nevertheless, we demonstrate that extracting during pumping (EDP) can significantly reduce parasitic losses due to both TASE and TPG.

  2. 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.

  3. Enhanced Output Power of PZT Nanogenerator by Controlling Surface Morphology of Electrode.

    PubMed

    Jung, Woo-Suk; Lee, Won-Hee; Ju, Byeong-Kwon; Yoon, Seok-Jin; Kang, Chong-Yun

    2015-11-01

    Piezoelectric power generation using Pb(Zr,Ti)O3(PZT) nanowires grown on Nb-doped SrTiO3(nb:STO) substrate has been demonstrated. The epitaxial PZT nanowires prepared by a hydrothermal method, with a diameter and length of approximately 300 nm and 7 μm, respecively, were vertically aligned on the substrate. An embossed Au top electrode was applied to maximize the effective power generation area for non-uniform PZT nanowires. The PZT nanogenerator produced output power density of 0.56 μW/cm2 with a voltage of 0.9 V and current of 75 nA. This research suggests that the morphology control of top electrode can be useful to improve the efficiency of piezoelectric power generation. PMID:26726616

  4. Picosecond fiber MOPA pumped supercontinuum source with 39 W output power.

    PubMed

    Chen, Kang Kang; Alam, Shaif-Ul; Price, Jonathan H V; Hayes, John R; Lin, Dejiao; Malinowski, Andrew; Codemard, Christophe; Ghosh, Debashri; Pal, Mrinmay; Bhadra, Shyamal K; Richardson, David J

    2010-03-15

    We report a picosecond fiber MOPA pumped supercontinuum source with 39 W output, spanning at least 0.4-2.25 microm at a repetition rate of 114.8 MHz. The 2m long PCF had a large, 4.4 microm diameter core and a high-delta design which led to an 80% coupling efficiency, high damage threshold and rapid generation of visible continuum generation from the picosecond input pulses. The high and relatively uniform power density across the visible spectral region was approximately 31.7 mW/nm corresponding to peak power density of approximately 12.5 W/nm for the 21 ps input pulses. The peak power density was increased to 26.9 W/nm by reducing the repetition rate to 28 MHz. This represents an increase in both average and peak power compared to previously reported visible supercontinuum sources from either CW pumped or pulsed-systems. PMID:20389559

  5. 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

  6. Influence of directionality and maximal power output on speech understanding with bone anchored hearing implants in single sided deafness.

    PubMed

    Krempaska, Silvia; Koval, Juraj; Schmid, Christoph; Pfiffner, Flurin; Kurz, Anja; Kompis, Martin

    2014-06-01

    Bone-anchored hearing implants (BAHI) are routinely used to alleviate the effects of the acoustic head shadow in single-sided sensorineural deafness (SSD). In this study, the influence of the directional microphone setting and the maximum power output of the BAHI sound processor on speech understanding in noise in a laboratory setting were investigated. Eight adult BAHI users with SSD participated in this pilot study. Speech understanding in noise was measured using a new Slovak speech-in-noise test in two different spatial settings, either with noise coming from the front and noise from the side of the BAHI (S90N0) or vice versa (S0N90). In both spatial settings, speech understanding was measured without a BAHI, with a Baha BP100 in omnidirectional mode, with a BP100 in directional mode, with a BP110 power in omnidirectional and with a BP110 power in directional mode. In spatial setting S90N0, speech understanding in noise with either sound processor and in either directional mode was improved by 2.2-2.8 dB (p = 0.004-0.016). In spatial setting S0N90, speech understanding in noise was reduced by either BAHI, but was significantly better by 1.0-1.8 dB, if the directional microphone system was activated (p = 0.046), when compared to the omnidirectional setting. With the limited number of subjects in this study, no statistically significant differences were found between the two sound processors. PMID:23700268

  7. 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. PMID:12930181

  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 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.

  9. 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.

  10. 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

  11. Effects of coolant temperature and pump power on the power output of solar-pumped solid state lasers

    NASA Astrophysics Data System (ADS)

    Thompson, George A.; Yogev, Amnon; Reich, A.; Oron, Moshe

    1992-11-01

    The temperature dependence of solar-pumped solid state lasers of Nd:YAG and two types of Nd:Cr:GSGG was studied over the temperature range of +30 to -60 C in a quasi-CW mode. All lasers had higher output powers at -40 C. The Nd:Cr:GSGG laser with a chromium concentration of 2.5 at. pct produced 70 W of power at -40 C, quasi-CW. If extrapolated to true CW operation this is equivalent to 350 W. The temperature dependence of the laser performance is attributed to changes in both the stimulated emission cross section and the resonator configuration.

  12. 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.

  13. Demonstration of a high output power 1533nm optical parametric oscillator pumped at 1064nm

    NASA Astrophysics Data System (ADS)

    Foltynowicz, Robert J.; Wojcik, Michael D.

    2010-10-01

    A high output power, eye-safe, LIDAR transmitter based on a KTA optical parametric oscillator (OPO) was demonstrated. The OPO was based on a two crystal, NCPM, KTA ring cavity which was doubly resonant. A 7ns, 30Hz, flashlamp-pumped, Q-switched Nd:YAG laser was injection seeded and used to pump the OPO. The OPO converted the 1064 nm pump beam into a 1533 nm signal wave and 3475 nm idler wave. In addition to demonstrating a high power OPO system, we investigated the effects of seeding the pump laser on the OPO's conversion efficiency, oscillation threshold, maximum signal power, and beam quality. The power conversion efficiency between the signal and the injection seeded pump was 22% with an oscillation threshold of 104 MW/cm2 (500 mJ) and a maximum signal power of 6.44 W (215 mJ). The power conversion efficiency between the signal and the unseeded pump was 24% with an oscillation threshold of 77 MW/cm2 (367mJ) and a maximum signal power of 7 W (233 mJ). The beam quality of the signal beam was produced an M2 =15. When the pump laser was seeded, the full angle divergence improved by nearly a factor of five.

  14. 275 W average output power from a femtosecond thin disk oscillator operated in a vacuum environment.

    PubMed

    Saraceno, Clara J; Emaury, Florian; Heckl, Oliver H; Baer, Cyrill R E; Hoffmann, Martin; Schriber, Cinia; Golling, Matthias; Südmeyer, Thomas; Keller, Ursula

    2012-10-01

    We present an ultrafast thin disk laser that generates an average output power of 275 W, which is higher than any other modelocked laser oscillator. It is based on the gain material Yb:YAG and operates at a pulse duration of 583 fs and a repetition rate of 16.3 MHz resulting in a pulse energy of 16.9 μJ and a peak power of 25.6 MW. A SESAM designed for high damage threshold initiated and stabilized soliton modelocking. We reduced the nonlinearity of the atmosphere inside the cavity by several orders of magnitude by operating the oscillator in a vacuum environment. Thus soliton modelocking was achieved at moderate amounts of self-phase modulation and negative group delay dispersion. Our approach opens a new avenue for power scaling femtosecond oscillators to the kW level. PMID:23188316

  15. 615 nm GaInNAs VECSEL with output power above 10 W.

    PubMed

    Kantola, Emmi; Leinonen, Tomi; Penttinen, Jussi-Pekka; Korpijärvi, Ville-Markus; Guina, Mircea

    2015-08-10

    A high-power optically-pumped vertical-external-cavity surface-emitting laser (VECSEL) generating 10.5 W of cw output power at 615 nm is reported. The gain mirror incorporated 10 GaInNAs quantum wells and was designed to have an emission peak in the 1230 nm range. The fundamental emission was frequency doubled to the red spectral range by using an intra-cavity nonlinear LBO crystal. The maximum optical-to-optical conversion efficiency was 17.5%. The VECSEL was also operated in pulsed mode by directly modulating the pump laser to produce light pulses with duration of ~1.5 µs. The maximum peak power for pulsed operation (pump limited) was 13.8 W. This corresponded to an optical-to-optical conversion efficiency of 20.4%. PMID:26367883

  16. Effects of superpositions of quantum states on quantum isoenergetic cycles: Efficiency and maximum power output

    NASA Astrophysics Data System (ADS)

    Niu, X. Y.; Huang, X. L.; Shang, Y. F.; Wang, X. Y.

    2015-04-01

    Superposition principle plays a crucial role in quantum mechanics, thus its effects on thermodynamics is an interesting topic. Here, the effects of superpositions of quantum states on isoenergetic cycle are studied. We find superposition can improve the heat engine efficiency and release the positive work condition in general case. In the finite time process, we find the efficiency at maximum power output in superposition case is lower than the nonsuperposition case. This efficiency depends on one index of the energy spectrum of the working substance. This result does not mean the superposition discourages the heat engine performance. For fixed efficiency or fixed power, the superposition improves the power or efficiency respectively. These results show how quantum mechanical properties affect the thermodynamical cycle.

  17. 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.

  18. 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

  19. High-power acoustic insult to living cultured cells as studied by high-frequency scanning acoustic microscopy

    NASA Astrophysics Data System (ADS)

    Miyasaka, Chiaki; Tittmann, Bernhard R.

    2002-06-01

    A plurality of articles discussing combined effects of acoustic high-pressure (mechanical factor) and heat (thermal factor) caused by acoustic vibration on biological tissues and cells has been published. Herein, we contribute the preliminary results describing the behavior of living human skin cells when separately applying shock waves and thermal insult to them. First, we gradually increased temperature of a culturing medium from 37.5 to 52 degree(s)C using the heat plate with temperature controller, and carried out in-situ observation of the cells grown on a substrate via the medium using a scanning acoustic microscope. Second, we provided the pressure using high power ultrasonic pulses generated by a laser induced ultrasonic shock wave system to the cells, wherein the pressure caused by the pulses was measured by a hydrophone, and wherein temperature was monitored by thermocouples. The cells were observed just after giving the impact. The difference between phenomena indicating cellular insult and injury (e.g., shrinkage or lift-off) were clearly visualized by the scanning acoustic microscope with frequency at 1.0 GHz.

  20. Comparison of power output during ergometer and track cycling in adolescent cyclists.

    PubMed

    Nimmerichter, Alfred; Williams, Craig A

    2015-04-01

    The aim of this study is to establish the level of agreement between test performance of young elite cyclists in a laboratory and a track field-based trial. Fourteen adolescent cyclists (age: 14.8 ± 1.1 years; (Equation is included in full-text article.): 63.5 ± 5.6 ml·min(-1)·kg(-1)) performed 3 tests of 10 seconds, 1 minute, and 3 minutes on an air-braked ergometer (Wattbike) and on a 250-m track using their own bikes mounted with mobile power meters (SRM). The agreement between the maximum and mean power output (Pmax and Pmean) measured on the Wattbike and SRM was assessed with the 95% limits of agreement (LoA). Power output was strongly correlated between Wattbike and SRM for all tests (r = 0.94-0.96; p < 0.001). However, power output was significantly higher on the Wattbike compared with track cycling during all tests. The bias and 95% LoA were 76 ± 78 W (8.8 ± 9.5%; p = 0.003, d = 0.38) for Pmax10s and 82 ± 55 W (10.9 ± 7.9%; p < 0.001, d = 0.46) for Pmean10s. During the 1- and 3-minute test, the bias and 95% LoA were 72 ± 30 W (17.9 ± 7.1%; p < 0.001, d = 0.84) and 28 ± 20 W (9.6 ± 6.1%; p < 0.001, d = 0.51), respectively. Laboratory tests, as assessed using a stationary ergometer, resulted in maximal and mean power output scores that were consistently higher than a track field-based test using a mobile ergometer. These results might be attributed to the technical ability of the riders and their experience to optimize gearing and cadence to maximize performance. Prediction of field-based testing on the track from laboratory tests should be used with caution. PMID:25353075

  1. 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.

  2. 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.

  3. 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.

  4. 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.

  5. Acoustic spectroscopy: A powerful analytical method for the pharmaceutical field?

    PubMed

    Bonacucina, Giulia; Perinelli, Diego R; Cespi, Marco; Casettari, Luca; Cossi, Riccardo; Blasi, Paolo; Palmieri, Giovanni F

    2016-04-30

    Acoustics is one of the emerging technologies developed to minimize processing, maximize quality and ensure the safety of pharmaceutical, food and chemical products. The operating principle of acoustic spectroscopy is the measurement of the ultrasound pulse intensity and phase after its propagation through a sample. The main goal of this technique is to characterise concentrated colloidal dispersions without dilution, in such a way as to be able to analyse non-transparent and even highly structured systems. This review presents the state of the art of ultrasound-based techniques in pharmaceutical pre-formulation and formulation steps, showing their potential, applicability and limits. It reports in a simplified version the theory behind acoustic spectroscopy, describes the most common equipment on the market, and finally overviews different studies performed on systems and materials used in the pharmaceutical or related fields. PMID:26976503

  6. 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, M.; 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.

  7. Wavelength dependence of maximal diffraction-limited output power of fiber lasers

    NASA Astrophysics Data System (ADS)

    Otto, Hans-Jürgen; Modsching, Norbert; Jauregui, Cesar; Limpert, Jens; Tünnermann, Andreas

    2015-03-01

    The threshold-like onset of mode instabilities is currently the main limitation for the scaling of the average output power of fiber-laser systems with diffraction limited beam quality. In this contribution wavelength shifting of the seed signal has been experimentally investigated in order to mitigate mode instabilities. Against the expectations, it is experimentally shown that the highest mode instabilities threshold is reached around 1030 nm and not for the smallest wavelength separation between pump and signal wavelength. This finding implies that the quantum defect is not the sole significant source for thermal heating in the fiber.

  8. 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.

  9. 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

  10. 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.

  11. 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.

  12. Lower limb alactic anaerobic power output assessed with different techniques in morbid obesity.

    PubMed

    Lafortuna, C L; Fumagalli, E; Vangeli, V; Sartorio, A

    2002-02-01

    Short-term alactic anaerobic performance in jumping (5 consecutive jumps with maximal effort), sprint running (8 m) and stair climbing (modified Margaria test) were measured in 75 obese subjects (BMI: 40.3+/-5.0 kg/m2) and in 36 lean control subjects (BMI: 22.4+/-3.2 kg/m2) of the same age and gender distribution. The results show that obese subjects attained a significantly lower specific (per unit body mass) power output both in jumping (W(spec,j); p<0.001) and stair climbing (W(spec,s); p<0.001) and run at a significantly lower average velocity (v; p<0.001) during sprinting. In spite of the different motor skillfulness required to accomplish the jumping and climbing tests, W(spec,s) (and hence the vertical velocity in climbing, v(v)) was closely correlated with W(spec,j) (R2=0.427, p<0.001). In jumping, although the average force during the positive work phase was significantly higher in obese subjects (p<0.001), no difference between the 2 groups was detected in absolute power. In stair climbing the absolute power output of obese resulted significantly higher (18%) than that of lean controls (p<0.001). In sprint running, the lower average horizontal velocity attained by obese subjects also entailed a different locomotion pattern with shorter step length (L(s); p<0.001), lower frequency (p<0.001) and longer foot contact time with ground (T(c,r); p<0.001). W(spec,j) seems to be a determinant of the poorer motor performance of obese, being significantly correlated with: I) the vertical displacement of the centre of gravity (R2=0.853, p<0.001) in jumping; II) with v(v) in stair climbing; and III) with T(c,r) (R2=0.492, p<0.001), L(s) (R2=0.266, p<0.001) and v (R2=0.454, p<0.001) in sprinting. The results suggest that obese individuals, although partially hampered in kinetic movements, largely rely on their effective specific power output to perform complex anaerobic tasks, and they suffer from the disproportionate excess of inert mass of fat. Furthermore, in view

  13. Suppression of Large-scaled PV Power Station Output Fluctuation using Sodium-Sulfur Battery

    NASA Astrophysics Data System (ADS)

    Akatsuka, Motoki; Hara, Ryoichi; Kita, Hiroyuki; Ito, Takamitsu; Ueda, Yoshinobu; Miwa, Shuya; Matsuno, Naoya; Takitani, Katsuyuki; Saito, Masami

    The large-scaled photovoltaic generation (PV) system that called “mega-solar” is expected to spread for penetrating PV system. But penetration of mega-solar may impact to stable operation of power system such as the load frequency control. As the one of solution for this problem, energy storage system (ESS) is tentatively installed to absorb short-term fluctuation of PV output. However, since the ESS is still expensive, it is favorable to reduce its required capacity of ESS for saving installation cost. In Wakkanai PV power station, sodium-sulfur (NAS) battery system is adopted as ESS and is operated to achieve suppression of short-term fluctuation and scheduled operation. In this paper, authors propose a control method of NAS battery system for reducing its MW capacity required for fluctuation suppressing based on characteristic of solar radiation.

  14. Compact second-harmonic generation laser module with 1 W optical output power at 490 nm.

    PubMed

    Fiebig, Christian; Sahm, Alexander; Uebernickel, Mirko; Blume, Gunnar; Eppich, Bernd; Paschke, Katrin; Erbert, Götz

    2009-12-01

    We demonstrate continues-wave 1 W at 490 nm on a 2.5 cm(3) micro-optical bench using single-path second-harmonic generation with a periodically poled MgO:LiNbO(3) bulk crystal. The pump laser is a distributed Bragg reflector tapered diode laser having a single-frequency spectrum and a pump power of 9.5 W. Based on that 1 W blue light could be achieved resulting in an optical conversion efficiency of 11%. Furthermore, the module has an output power stability of better than 2% and the blue laser beam shows an nearly diffraction limited beam quality of M(2)(sigma) = 1.2 in vertical and M(2)(sigma) = 2 in lateral direction. PMID:20052204

  15. 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. PMID:22587076

  16. 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.

  17. Decreasing effective reflectivity of the output coupler in the power scaling of fiber lasers

    NASA Astrophysics Data System (ADS)

    Hejaz, K.; Shayganmanesh, M.; Roohforouz, A.; Rezaei-Nasirabad, R.; Heidariazar, A.; Vatani, V.; Hassan Nabavi, S.

    2016-03-01

    Increasing power leads to the spectral broadening of fiber laser beams. In this effect the spectral line width of the laser beam becomes broader than that of the output coupler (OC) due to power scaling. Therefore, the effective reflectivity of the OC mirror decreases. In this paper, this phenomenon is investigated theoretically and experimentally. A Liekki Application Designer V3.3 was used for the theoretical investigation and the experiments were conducted during the fabrication of a 630W fiber laser. Given the excellent agreement between the simulation and the experimental results, a decrease in the effective reflectivity of the OC mirror was proved. The decrease in the effective reflectivity of the OC mirror changes some of the laser parameters, such as optical efficiency, longitudinal distribution of population inversion and the backward power inside the resonator. This may also lead to power instability. The effects of a decrease in the reflectivity of the OC on the mentioned parameters of the fiber laser are investigated in the present paper. Finally, recommendations for choosing appropriate OC mirror parameters in high-power (kW class) fiber lasers are suggested.

  18. 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.

  19. 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).

  20. 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.

  1. 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. PMID:25121598

  2. 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. PMID:23580727

  3. Efficiency and output power of thermoelectric module by taking into account corrected Joule and Thomson heat

    NASA Astrophysics Data System (ADS)

    Kim, Hee Seok; Liu, Weishu; Ren, Zhifeng

    2015-09-01

    The maximum conversion efficiency of a thermoelectric module composed of p- and n-type materials has been widely calculated using a constant property model since the 1950s, but this conventional model is only valid in limited conditions and no Thomson heat is accounted for. Since Thomson heat causes the efficiency under- or over-rated depending on the temperature dependence of Seebeck coefficient, it cannot be ignored especially in large temperature difference between the hot and cold sides. In addition, incorrect Joule heat is taken into consideration for heat flux evaluation of a thermoelectric module at thermal boundaries due to the assumption of constant properties in the conventional model. For this reason, more practical predictions for efficiency and output power and its corresponding optimum conditions of p- and n-type materials need to be revisited. In this study, generic formulae are derived based on a cumulative temperature dependence model including Thomson effect. The formulae reliably predict the maximum efficiency and output power of a thermoelectric module at a large temperature.

  4. Influence of cadence, power output and hypoxia on the joint moment distribution during cycling.

    PubMed

    Mornieux, Guillaume; Guenette, Jordan A; Sheel, A William; Sanderson, David J

    2007-12-01

    The purpose of this study was to use a hypoxic stress as a mean to disrupt the normal coordinative pattern during cycling. Seven male cyclists pedalled at three cadence (60, 80, 100 rpm) and three power output (150, 250, 350 W) conditions in normoxia and hypoxia (15% O2). Simultaneous measurements of pedal force, joint kinematics, % oxyhaemoglobin saturation, and minute ventilation were made for each riding condition. A conventional inverse dynamics approach was used to compute the joint moments of force at the hip, knee, and ankle. The relative contribution of the joint moments of force with respect to the total moment was computed for each subject and trial condition. Overall, the ankle contributed on average 21%, the knee 29% and the hip 50% of the total moment. This was not affected by the relative inspired oxygen concentration. Results showed that the relative ankle moment of force remained at 21% regardless of manipulation. The relative hip moment was reduced on average by 4% with increased cadence and increased on average by 4% with increased power output whereas the knee moment responded in the opposite direction. These results suggest that the coordinative pattern in cycling is a dominant characteristic of cycling biomechanics and remains robust even in the face of arterial hypoxemia. PMID:17846783

  5. 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

  6. 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.

  7. 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.

  8. Output power fluctuations due to different weights of macro particles used in particle-in-cell simulations of Cerenkov devices

    NASA Astrophysics Data System (ADS)

    Bao, Rong; Wang, Hongguang; Li, Yongdong; Liu, Chunliang

    2016-07-01

    The output power fluctuations caused by weights of macro particles used in particle-in-cell (PIC) simulations of a backward wave oscillator and a travelling wave tube are statistically analyzed. It is found that the velocities of electrons passed a specific slow-wave structure form a specific electron velocity distribution. The electron velocity distribution obtained in PIC simulation with a relative small weight of macro particles is considered as an initial distribution. By analyzing this initial distribution with a statistical method, the estimations of the output power fluctuations caused by different weights of macro particles are obtained. The statistical method is verified by comparing the estimations with the simulation results. The fluctuations become stronger with increasing weight of macro particles, which can also be determined reversely from estimations of the output power fluctuations. With the weights of macro particles optimized by the statistical method, the output power fluctuations in PIC simulations are relatively small and acceptable.

  9. 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.

  10. 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.

  11. 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.

  12. Development of a criterion method to determine peak mechanical power output in a countermovement jump.

    PubMed

    Owen, Nick J; Watkins, James; Kilduff, Liam P; Bevan, Huw R; Bennett, Mark A

    2014-06-01

    There is a general agreement that the most valid method of measuring peak lower-body mechanical power output (LBPP) in a countermovement jump (CMJ) is by analysis of the corresponding vertical component of the ground reaction force (VGRF)-time history of the jump. However, there is no published standard protocol. The purpose of this study was to establish a standard protocol. The variables necessary to define a valid and reliable CMJ method were: (a) vertical force range, (b) force sampling and integration frequency, (c) method of integration, (d) determination of body weight (BW), and (e) determination of the initiation of the CMJ. Countermovement jumps off a force platform (FP) were performed by 15 male professional rugby players. The 5 variables were then optimized to maximize the reliability and validity of the measure of LBPP. Errors of <1% (p ≤ 0.05) in the measurement of LBPP were obtained using the following specification: (a) 6 times BW (using a 16-bit analog to digital converter), (b) 1,000 Hz, (c) Simpson's rule or the trapezoidal rule, (d) mean VGRF for 1 second of quiet standing immediately before jump signal, and (e) 30 ms before the instant BW ± 5 SD is exceeded after the jump signal. Peak lower-body power output was most sensitive to variables 4 and 5. It was concluded that this study has established a standard protocol for the criterion method of measuring peak power in a CMJ using an FP. As all other estimates and less reliable methods of determining LBPP in a CMJ rely on the FP method for calibration, it is proposed that this protocol be used as the basis of future criterion measures using a FP. PMID:24276298

  13. 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

  14. 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

  15. 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. PMID:16767608

  16. Ultrasonic acoustic health monitoring of ball bearings using neural network pattern classification of power spectral density

    NASA Astrophysics Data System (ADS)

    Kirchner, William; Southward, Steve; Ahmadian, Mehdi

    2010-03-01

    This paper presents a generic passive non-contact based approach using ultrasonic acoustic emissions (UAE) to facilitate the neural network classification of bearing health, and more specifically the bearing operating condition. The acoustic emission signals used in this study are in the ultrasonic range (20-120 kHz). A direct benefit of microphones capable of measurements in this frequency range is their inherent directionality. Using selected bands from the UAE power spectrum signature, it is possible to pose the health monitoring problem as a multi-class classification problem, and make use of a single neural network to classify the ultrasonic acoustic emission signatures. Artificial training data, based on statistical properties of a significantly smaller experimental data set is used to train the neural network. This specific approach is generic enough to suggest that it is applicable to a variety of systems and components where periodic acoustic emissions exist.

  17. 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.

  18. Recovery of Power Output and Heart Rate Kinetics During Repeated Bouts of Rowing Exercise with Different Rest Intervals

    PubMed Central

    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 Points The 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

  19. 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.

  20. 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

  1. Non-linear relationship between O2 uptake and power output at high intensities of exercise in humans.

    PubMed

    Zoladz, J A; Rademaker, A C; Sargeant, A J

    1995-10-01

    1. A slow component to pulmonary oxygen uptake (VO2) is reported during prolonged high power exercise performed at constant power output at, or above, approximately 60% of the maximal oxygen uptake. The magnitude of the slow component is reported to be associated with the intensity of exercise and to be largely accounted for by an increased VO2 across the exercising legs. 2. On the assumption that the control mechanism responsible for the increased VO2 is intensity dependent we hypothesized that it should also be apparent in multi-stage incremental exercise tests with the result that the VO2-power output relationship would be curvilinear. 3. We further hypothesized that the change in the VO2-power output relationship could be related to the hierarchical recruitment of different muscle fibre types with a lower mechanical efficiency. 4. Six subjects each performed five incremental exercise tests, at pedalling rates of 40, 60, 80, 100 and 120 rev min-1, over which range we expected to vary the proportional contribution of different fibre types to the power output. Pulmonary VO2 was determined continuously and arterialized capillary blood was sampled and analysed for blood lactate concentration ([lactate]b). 5. Below the level at which a sustained increase in [lactate]b was observed pulmonary VO2 showed a linear relationship with power output; at high power outputs, however, there was an additional increase in VO2 above that expected from the extrapolation of that linear relationship, leading to a positive curvilinear VO2-power output relationship. 6. No systematic effect on the magnitude or onset of the 'extra' VO2 was found in relation to pedalling rate, which suggests that it is not related to the pattern of motor unit recruitment in any simple way. PMID:8568657

  2. 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.

  3. 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.

  4. Photonic instantaneous frequency measurement with digital output based on dispersion induced power fading functions

    NASA Astrophysics Data System (ADS)

    Chen, Ying; Yang, Bo; Chi, Hao; Jin, Xiaofeng; Zheng, Shilie; Zhang, Xianmin

    2013-04-01

    A novel photonic approach to realize the instantaneous microwave frequency measurement with digital output is proposed and demonstrated experimentally. Based on the power fading function of a double-sideband modulated microwave signal transmitting in a dispersive fiber channel, the microwave frequency to digital code mapping can be realized in a multi-channel system where each channel is configured with a predetermined amount of dispersion. The coding process involved here is similar to that of the photonic analog-to-digital conversion. The principle of the system is discussed in detail. An experiment is carried out, in which the frequency identification with 4-bit quantization levels in 17.5 GHz measurement range is demonstrated. The measurement range and the resolution are discussed theoretically and numerically.

  5. 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) (

  6. The role of sense of effort on self-selected cycling power output

    PubMed Central

    Christian, Ryan J.; Bishop, David J.; Billaut, François; Girard, Olivier

    2014-01-01

    Purpose: We explored the effects of the sense of effort and accompanying perceptions of peripheral discomfort on self-selected cycle power output under two different inspired O2 fractions. Methods: On separate days, eight trained males cycled for 5 min at a constant subjective effort (sense of effort of ‘3’ on a modified Borg CR10 scale), immediately followed by five 4-s progressive submaximal (sense of effort of “4, 5, 6, 7, and 8”; 40 s between bouts) and two 4-s maximal (sense of effort of “10”; 3 min between bouts) bouts under normoxia (NM: fraction of inspired O2 [FiO2] 0.21) and hypoxia (HY: [FiO2] 0.13). Physiological (Heart Rate, arterial oxygen saturation (SpO2) and quadriceps Root Mean Square (RMS) electromyographical activity) and perceptual responses (overall peripheral discomfort, difficulty breathing and limb discomfort) were recorded. Results: Power output and normalized quadriceps RMS activity were not different between conditions during any exercise bout (p > 0.05) and remained unchanged across time during the constant-effort cycling. SpO2 was lower, while heart rate and ratings of perceived difficulty breathing were higher under HY, compared to NM, at all time points (p < 0.05). During the constant-effort cycling, heart rate, overall perceived discomfort, difficulty breathing and limb discomfort increased with time (all p < 0.05). All variables (except SpO2) increased along with sense of effort during the brief progressive cycling bouts (all p < 0.05). During the two maximal cycling bouts, ratings of overall peripheral discomfort displayed an interaction between time and condition with ratings higher in the second bout under HY vs. NM conditions. Conclusion: During self-selected, constant-effort and brief progressive, sub-maximal, and maximal cycling bouts, mechanical work is regulated in parallel to the sense of effort, independently from peripheral sensations of discomfort. PMID:24744734

  7. Effect of inspiratory muscle training with an intermediate load on inspiratory power output in COPD.

    PubMed

    Villafranca, C; Borzone, G; Leiva, A; Lisboa, C

    1998-01-01

    There is very little information about the effect of inspiratory muscle training on inspiratory flow (V'I) and thus on power output (PO) in patients with chronic obstructive pulmonary disease (COPD). In this study we aimed to evaluate the changes induced by training on the determinants of PO. Thirty one patients with severe COPD were randomly divided into: Group 1, trained with 30% maximal inspiratory pressure (PI,max); Group 2, with 10% PI,max; and Group 3 also trained with 30% PI,max, but the breathing pattern was evaluated while performing the training manoeuvres along inspiratory muscle training (IMT). All groups used a threshold device for 10 weeks. The PO for each of the loads during an incremental threshold test was evaluated prior to and after training. Maximal PO (POmax) increased in all groups, but the increment was higher in groups trained with 30% PI,max (p<0.005), mainly due to an increase in V'I. Group 3 showed a progressive increase in V'I (p<0.001) during the training manoeuvres in spite of an increase in load along IMT. In addition, the load after IMT was overcome with a shorter inspiratory time (tI) (p<0.02), a smaller tI/total duration of the respiratory cycle (t(tot)), (p<0.001) with no change in tidal volume or t(tot). The increment in POmax in this group correlated with the V'I generated while training (r=0.85; p<0.0001). We conclude that in patients with chronic obstructive pulmonary disease, the use of an intermediate threshold load for training improves power output mainly by increasing inspiratory flow, an effect consistent with an increase in shortening velocity of inspiratory muscles. PMID:9543266

  8. 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".

  9. Agreement between the force platform method and the combined method measurements of power output during the loaded countermovement jump.

    PubMed

    Mundy, Peter D; Lake, Jason P; Carden, Patrick J C; Smith, Neal A; Lauder, Mike A

    2016-03-01

    There are two perceived criterion methods for measuring power output during the loaded countermovement jump (CMJ): the force platform method and the combined method (force platform + optoelectronic motion capture system). Therefore, the primary aim of the present study was to assess agreement between the force platform method and the combined method measurements of peak power and mean power output during the CMJ across a spectrum of loads. Forty resistance-trained team sport athletes performed maximal effort CMJ with additional loads of 0 (body mass only), 25, 50, 75 and 100% of body mass (BM). Bias was present for peak velocity, mean velocity, peak power and mean power at all loads investigated, and present for mean force up to 75% of BM. Peak velocity, mean velocity, peak power and mean power 95% ratio limits of agreement were clinically unacceptable at all loads investigated. The 95% ratio limits of agreement were widest at 0% of BM and decreased linearly as load increased. Therefore, the force platform method and the combined method cannot be used interchangeably for measuring power output during the loaded CMJ. As such, if power output is to be meaningfully investigated, a standardised method must be adopted. PMID:27075378

  10. 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

  11. 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

  12. 264 W output power at 1585 nm in Er-Yb codoped fiber laser using in-band pumping.

    PubMed

    Jebali, M A; Maran, J-N; LaRochelle, S

    2014-07-01

    We demonstrate a high-power cladding-pumped Er-Yb codoped fiber laser with 74% efficiency. A pump-limited output power of 264 W is obtained using in-band pumping at 1535 nm. We compare the efficiency of 1480 and 1535 nm pumping through numerical simulations and experimental measurements. PMID:24978785

  13. QCW diode-side-pumped Nd:YAG ceramic laser with 247 W output power at 1123 nm

    NASA Astrophysics Data System (ADS)

    Li, C. Y.; Peng, Q. J.; Wang, B. S.; Bo, Y.; Cui, D. F.; Xu, Z. Y.; Feng, X. Q.; Pan, Y. B.

    2011-05-01

    We demonstrate for the first time a diode-side-pumped quasi-continuous-wave (QCW) operation of a 1123 nm Nd:YAG ceramic laser. The single 1123 nm wavelength is acquired through precise coating. With a pump power of 1000 W, an output power of 247 W is obtained, corresponding to an optical-optical conversion efficiency of 24.7%. At the maximal output power, the pulse repetition rate and pulse width are measured to be 1.1 kHz and 180 μs, respectively. The numerical simulations for wavelength selectivity from 1112, 1116 and 1123 nm are discussed in detail.

  14. CMOS self-powered monolithic light-direction sensor with digitalized output.

    PubMed

    Wang, Hongyi; Luo, Tao; Lu, Zhijian; Song, Hongjiang; Christen, Jennifer Blain

    2014-05-01

    We present a novel self-powered chip to detect the direction of incident light. This chip directly provides digitized output without the need of any off-chip power supply or optical or mechanical components. The chip was implemented in a standard 0.5 μm CMOS process. A microscale metal baffle was created by stacking all metal layers, contacts, and vias available in the process to produce on-chip shadowing. N-well/p+ photodiode arrays are located on both sides of the baffle to sense light. The photocurrent generated by a photodiode depends on the size of the photodiode and the shadowing. The shadowed area depends on the incident angle of the light. A current mirror circuit is used to compare the currents generated by the photodiodes on the opposite sides of the baffle and, consequently, provide a digital signal to indicate the incident light angle. Compared with the ideal linear digital light-angle detector with the same resolution, the presented sensor achieved the maximum error of only 2 deg over 110 deg test range. PMID:24784060

  15. 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. PMID:25371997

  16. 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).

  17. Systematic Observation of Time-Dependent Phenomena in the RF Output Spectrum of High Power Gyrotrons

    NASA Astrophysics Data System (ADS)

    Schlaich, Andreas; Gantenbein, Gerd; Kern, Stefan; Thumm, Manfred

    2012-09-01

    At IHM/KIT, high power gyrotrons with conventional cavity (e.g. 1 MW CW at 140 GHz for the stellarator Wendelstein 7-X) and coaxial cavity (2 MW shortpulse at 170 GHz for ITER) for fusion applications are being developed and verified experimentally. Especially with respect to the problem of parasitic RF oscillations in the beam tunnel of some W7-X tubes, investigations of the gyrotron RF output spectrum have proved to be a valuable source of diagnostic information. Signs of transient effects in millisecond pulses, like frequency switching or intermittent low-frequency modulation, have indicated that truly time-dependent measurements with high frequency resolution and dynamic range could give deeper insight into these phenomena. In this paper, an improved measurement system is presented, which employs a fast oscilloscope as receiver. Shorttime Fourier transform (STFT) is applied to the time-domain signal, yielding time-variant spectra with frequency resolutions only limited by acquisition length and STFT segmentation choice. Typical reasonable resolutions are in the range of 100 kHz to 10 MHz with a currently memory-limited maximum acquisition length of 4 ms. A key feature of the system consists in the unambiguity of frequency measurement: The system receives through two parallel channels, each using a harmonic mixer (h = 9 - 12) to convert the signal from RF millimeter wave frequencies (full D-Band, 110 - 170 GHz) to IF (0 - 3 GHz). For each IF output signal of each individual mixer, injection side and receiving harmonic are initially not known. Using accordingly determined LO frequencies, this information is retrieved from the redundancy of the channels, yielding unambiguously reconstructed RF spectra with a total span of twice the usable receiver IF bandwidth, up to ≈ 6 GHz in our case. Using the system, which is still being improved continuously, various transient effects like cavity mode switching, parasitic oscillation frequency variation, and lowfrequency

  18. 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

  19. 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)

  20. Random Density Inhomogeneities and Focusability of the Output Pulses for Plasma-based Powerful Backward Raman Amplifiers

    SciTech Connect

    A.A. Solodov; V.M. Malkin; N.J. Fisch

    2003-01-21

    Random plasma density inhomogeneities may defocus the output pulses of powerful backward Raman amplifiers (BRA). Because of ultra-high intensities of even non-focused BRA outputs, such distortions, if occur, are then difficult to correct. We derive a simple expression for the largest BRA length for which the output pulse focusability is not yet spoiled. Interestingly, this limitation does not depend on the pump laser intensity. We also note a useful effect of plasma inhomogeneities that might help to suppress premature pump backscattering by thermal noise.

  1. 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.

  2. 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.

  3. 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

  4. 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. PMID:23711074

  5. Effect of cycling position on oxygen uptake and preferred cadence in trained cyclists during hill climbing at various power outputs.

    PubMed

    Harnish, Chris; King, Deborah; Swensen, Tom

    2007-03-01

    Numerous researchers have studied the physiological responses to seated and standing cycling, but actual field data are sparse. One open issue is the preferred cadence of trained cyclists while hill climbing. The purpose of this study, therefore, was to examine the affect of cycling position on economy and preferred cadence in trained cyclists while they climbed a moderate grade hill at various power outputs. Eight trained cyclists (25.8 +/- 7.2 years, [Formula: see text] 68.8 +/- 5.0 ml kg(-1) min(-1), peak power 407.6 +/- 69.0 W) completed a seated and standing hill climb at approximately 50, 65 and 75% of peak power output (PPO) in the order shown, although cycling position was randomized, i.e., half the cyclists stood or remained seat on their first trial at each power output. Cyclists also performed a maximal trial unrestricted by position. Heart rate, power output, and cadence were measured continuously with a power tap; ventilation [Formula: see text], BF and cadence were significantly higher with seated climbing at all intensities; there were no other physiological differences between the climbing positions. These data support the premise that trained cyclists are equally economical using high or low cadences, but may face a limit to benefits gained with increasing cadence. PMID:17165053

  6. High frequency formulation for the acoustic power spectrum due to cascade-turbulence interaction.

    PubMed

    Cheong, Cheolung; Joseph, Phillip; Lee, Soogab

    2006-01-01

    This paper investigates the noise radiated by a cascade of flat-plate airfoils interacting with homogeneous, isotropic turbulence. An analytic formulation for the spectrum of acoustic power of a two-dimensional flat-plate is derived. The main finding of this paper is that the acoustic power spectrum from the cascade of flat airfoils may be split into two distinct frequency regions of low frequency and high frequency, separated by a critical frequency. Below this frequency, cascade effects due to the interaction between neighboring airfoils are shown to be important. At frequencies above the critical frequency, cascade effects are shown to be relatively weak. In this frequency range, acoustic power is shown to be approximately proportional to the number of blades. Based on this finding at high frequencies, an approximate expression is derived for the power spectrum that is valid above the critical frequency and which is in excellent agreement with the exact expression for the broadband power spectrum. The formulation is used to perform a parametric study on the effects on the power spectrum of the blade number, stagger angle, gap-chord ratio, and Mach number. The theory is also shown to provide a close fit to the measured spectrum of rotor-stator interaction. PMID:16454269

  7. 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.

  8. 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.

  9. 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.

  10. Power method for calculating the far acoustic field of the helicopter lift rotor

    NASA Astrophysics Data System (ADS)

    Samokhin, V. F.

    2011-05-01

    A semiempirical method for calculating the far acoustic field of the lift rotor of a helicopter operating in the regime of oblique flow over it is described. The basic parametric relations for the acoustic radiation power of rotor noise components have been obtained on the basis of the Lamb idea that vortex-free motion arises under the action of a periodic force on an infinitely small volume of the medium. All sources of lift rotor noise are subdivided into two groups pertaining, respectively, to the inductive and profile parts of the total power supplied to the rotor. A comparison has been made between the results of calculation of the harmonic components of lift rotor noise made on the basis of the power method and the experimental data for the Mi-28 helicopter.

  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. 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.

  13. 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

  14. Fully automated 1.5 MHz FDML laser with more than 100mW output power at 1310 nm

    NASA Astrophysics Data System (ADS)

    Wieser, Wolfgang; Klein, Thomas; Draxinger, Wolfgang; Huber, Robert

    2015-07-01

    While FDML lasers with MHz sweep speeds have been presented five years ago, these devices have required manual control for startup and operation. Here, we present a fully self-starting and continuously regulated FDML laser with a sweep rate of 1.5 MHz. The laser operates over a sweep range of 115 nm centered at 1315 nm, and provides very high average output power of more than 100 mW. We characterize the laser performance, roll-off, coherence length and investigate the wavelength and phase stability of the laser output under changing environmental conditions. The high output power allows optical coherence tomography (OCT) imaging with an OCT sensitivity of 108 dB at 1.5 MHz.

  15. 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.

  16. SM green fiber laser operating in CW and QCW regimes and producing over 550W of average output power

    NASA Astrophysics Data System (ADS)

    Gapontsev, Valentin; Avdokhin, Alexey; Kadwani, Pankaj; Samartsev, Igor; Platonov, Nikolai; Yagodkin, Roman

    2014-02-01

    We report a single-mode (SM) green laser based on single-pass frequency doubling of a linearly-polarized narrowlinewidth Yb fiber laser in LBO crystal, and configured to operate in a range of regimes from continuous-wave (CW) to high-repetition-rate quasi-continuous-wave (QCW). Adjusting the duty cycle, we maintained high second harmonic generation (SHG) efficiency for various output powers. Average powers of over 550W in QCW and over 350W in CW regimes were obtained with the wall-plug efficiency up to 15%, opening the possibility to creating new class of simple, compact and efficient single-mode green lasers with output power up to 1kW and above. The same approach could also be used to create high-power lasers operating at other wavelengths in ultraviolet and visible spectral ranges.

  17. 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.

  18. Single frequency 1560nm Er:Yb fiber amplifier with 207W output power and 50.5% slope efficiency

    NASA Astrophysics Data System (ADS)

    Creeden, Daniel; Pretorius, Herman; Limongelli, Julia; Setzler, Scott D.

    2016-03-01

    High power fiber lasers/amplifiers in the 1550nm spectral region have not scaled as rapidly as Yb-, Tm-, or Ho-doped fibers. This is primarily due to the low gain of the erbium ion. To overcome the low pump absorption, Yb is typically added as a sensitizer. Although this helps the pump absorption, it also creates a problem with parasitic lasing of the Yb ions under strong pumping conditions, which generally limits output power. Other pump schemes have shown high efficiency through resonant pumping of erbium only without the need for Yb as a sensitizer [1-2]. Although this can enable higher power scaling due to a decrease in the thermal loading, resonant pumping methods require long fiber lengths due to pump bleaching, which may limit the power scaling which can be achieved for single frequency output. By using an Er:Yb fiber and pumping in the minima of the Yb pump absorption at 940nm, we have been able to simultaneously generate high power, single frequency output at 1560nm while suppressing the 1-micron ASE and enabling higher efficiency compared to pumping at the absorption peak at 976nm. We have demonstrated single frequency amplification (540Hz linewidth) to 207W average output power with 49.3% optical efficiency (50.5% slope efficiency) in an LMA Er:Yb fiber. We believe this is the highest reported efficiency from a high power 9XXnm pumped Er:Yb-doped fiber amplifier. This is significantly more efficient that the best-reported efficiency for high power Er:Yb doped fibers, which, to-date, has been limited to ~41% slope efficiency [3].

  19. Tapered lasers emitting at 650 nm with 1 W output power with nearly diffraction-limited beam quality.

    PubMed

    Adamiec, Pawel; Sumpf, Bernd; Rüdiger, Ingo; Fricke, Jörg; Hasler, Karl-Heinz; Ressel, Peter; Wenzel, Hans; Zorn, Martin; Erbert, Götz; Tränkle, Günther

    2009-08-15

    High-brightness tapered lasers emitting around 650 nm were developed. Devices 2 mm long with a200-microm-long straight section, 1800-microm-long tapered section, and 4 degrees taper angle reached 1 W output power in CW operation with a nearly diffraction-limited beam quality. PMID:19684814

  20. 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)

  1. Maximal power output and perceptual fatigue responses during a Division I female collegiate soccer season.

    PubMed

    McLean, Blake D; Petrucelli, Chris; Coyle, Edward F

    2012-12-01

    The purpose of this study was to investigate how maximal power output (PMAX), as measured via the inertial load cycling technique, changes throughout a collegiate soccer season in relation to training load completed. The current investigation took place throughout the 2010 Big XII soccer season. Nineteen Division I female collegiate soccer players (age: 19.9 ± 1.2 years, stature: 165.1 ± 6.6 cm, mass: 61.0 ± 6.8 kg) from the same team completed regular inertial load cycling tests and perceptual fatigue questionnaires throughout the season. Players were divided into STARTERS and NON-STARTERS based on percentage of matches started throughout the season. The results demonstrated that STARTERS experience much greater load throughout the season than NON-STARTERS (2247 ± 176 arbitrary units [AU] and 1585 ± 174 AU, p < 0.05), accounted for by increased load during matches. This increased load throughout the season was accompanied by decline in PMAX in STARTERS (to 92.3 ± 6.6%, p < 0.05), whereas PMAX was maintained in NON-STARTERS for the duration of the season (99.0 ± 4.9%). Furthermore, STARTERS experienced greater muscle soreness throughout the in-season period compared with NON-STARTERS. The main finding of this study is that PMAX declined throughout the middle and latter parts of the season in STARTERS, after experiencing significantly greater match loads than NON-STARTERS throughout the season. The current findings, combined with previous investigations, suggest that load needs to be carefully monitored throughout the in-season period to maintain optimal neuromuscular performance throughout a team's entire sporting season. PMID:22996020

  2. 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.

  3. 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

  4. 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., Jr.

    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.

  5. 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.

  6. Power law statistics of force and acoustic emission from a slowly penetrated granular bed

    NASA Astrophysics Data System (ADS)

    Matsuyama, K.; Katsuragi, H.

    2014-01-01

    Penetration-resistant force and acoustic emission (AE) from a plunged granular bed are experimentally investigated through their power law distribution forms. An AE sensor is buried in a glass bead bed. Then, the bed is slowly penetrated by a solid sphere. During the penetration, the resistant force exerted on the sphere and the AE signal are measured. The resistant force shows power law relation to the penetration depth. The power law exponent is independent of the penetration speed, while it seems to depend on the container's size. For the AE signal, we find that the size distribution of AE events obeys power laws. The power law exponent depends on grain size. Using the energy scaling, the experimentally observed power law exponents are discussed and compared to the Gutenberg-Richter (GR) law.

  7. Determining the nominal power transfer coefficient for passive surface acoustic wave devices

    NASA Astrophysics Data System (ADS)

    Timoshenko, A. N.; Palamarchuk, A. A.; Semenko, A. I.

    1982-05-01

    A method for calculating the nominal power transfer coefficient of passive SAW devices operating in a linear mode is described. Relations of practical importance are obtained, making it possible, on the basis of known characteristics of acousto-electric transducers and acoustic lines, to determine the losses incurred by devices when they are connected to radioelectronic equipment. The relations also permit an assessment of the uniformity of the amplitude-frequency characteristics of the devices.

  8. 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.

  9. 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.

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

    NASA Astrophysics Data System (ADS)

    Luchau, David W.; Sinkevich, Valery G.; Wernsman, Bernard; Mulder, Daniel 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).

  11. 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

  12. 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.}

  13. 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

  14. Evolutionary programming-based methodology for economical output power from PEM fuel cell for micro-grid application

    NASA Astrophysics Data System (ADS)

    El-Sharkh, M. Y.; Rahman, A.; Alam, M. S.

    This paper presents a methodology for finding the optimal output power from a PEM fuel cell power plant (FCPP). The FCPP is used to supply power to a small micro-grid community. The technique used is based on evolutionary programming (EP) to find a near-optimal solution of the problem. The method incorporates the Hill-Climbing technique (HCT) to maintain feasibility during the solution process. An economic model of the FCPP is used. The model considers the production cost of energy and the possibility of selling and buying electrical energy from the local grid. In addition, the model takes into account the thermal energy output from the FCPP and the thermal energy requirement for the micro-grid community. The results obtained are compared against a solution based on genetic algorithms. Results are encouraging and indicate viability of the proposed technique.

  15. 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

  16. 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.

  17. 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.

  18. 0.7 MW output power from a two-arm coherently combined Q-switched photonic crystal fiber laser.

    PubMed

    Rosenstein, Boris; Shirakov, Avry; Belker, Daniel; Ishaaya, Amiel A

    2014-03-24

    We demonstrate a high peak power, Q-switched pulsed, intracavity coherently combined fiber laser system. The system is based on two Yb-doped, rod-type, photonic crystal fibers which are passively phase-locked and combined into the single output beam in a power oscillator configuration. Experimental evidence indicate that this oscillator system provides record high peak power of ∼ 0.7 MW with pulse duration of ∼ 10 ns at 1 kHz repetition rate. The measured beam quality shows near-diffraction-limited operation of the coherently combined system. PMID:24663989

  19. An integrated modular power-aware microsensor architecture and application to unattended acoustic vehicle tracking

    NASA Astrophysics Data System (ADS)

    Bajura, Michael; Schott, Brian; Flidr, Jaroslav; Czarnaski, Joe; Worth, Carl; Tho, Tam; Wang, Li

    2005-05-01

    We introduce a truly modular, power-aware, distributed microsensor architecture, capable of seamlessly spanning performance metrics from point-optimized low-power to point-optimized high-power applications. This type of performance is often needed in unattended ground sensor applications such as acoustic sensing and tracking, where long periods of minimal sensing activity are intermixed with short periods of intense sensor processing. The system design and implementation of a microsensor platform based on this architecture are described with experimental results. We show that although building a modular power-aware system requires additional hardware components, it results in system capable of rapid physical hardware and software reconfiguration with module reuse for new applications, while achieving a significant decrease in overall system power.

  20. 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

  1. 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. PMID:25607308

  2. 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.

  3. 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

  4. Microtensile strength of resin cement bond to indirect composite treated by different output powers of Er:YAG laser.

    PubMed

    Garshasbzadeh, Nazanin Zeinab; Mirzaie, Mansoreh; Yassini, Esmaeil; Shahabi, Sima; Benedicenti, Stefano; Angiero, Francesca; Chiniforush, Nasim

    2016-04-01

    The study aimed to evaluate the effect of different output powers of Er:YAG laser on microtensile bonding strength of indirect composite to resin cements.36 indirect composite blocks (GC Gradia DA2, Japan) size 15 × 10 × 10 mm(3) were constructed, and divided into 12 groups, as follows:G1: control group (no treatment); Groups G2 to G6: treated with Er:YAG laser (2,940 nm) in noncontact mode, frequency 20 Hz, pulse duration 470 µs, with output power ranging from 2W to 6W; Groups G7 sandblasting, Groups 8 to G12: as Groups G2 to G 6 with preparatory sandblasting. One specimen from each group was analyzed by SEM; each specimen was fixed to a specialized metal jig using cyanoacrylate (Mitreapel, Beta Kimya San. Ve TIC, Iran) and debonded under tension with a universal testing machine (Zwick, Germany) at a crosshead speed of 0.5 mm min(-1). Sandblasting and laser can improve bond strength above an energy level of 150 mJ. SEM evaluation of laser-treated specimens showed irregularities and deep undercuts. T test analysis showed no significant difference between sandblasted and non-sandblasted group, with laser output power of 0, 100, or 150 mJ (P = 0.666, P = 0.875, and P =  .069); in the specimens irradiated with energy output of 200, 250, or 300 mJ, sandblasted specimens showed higher bond strength than non-sandblasted ones. The results demonstrate that, in composite resin irradiated with laser at energy output of 200-300 mJ, sandblasting might be a suitable procedure to enhance bond strength of resin cement. PMID:26873266

  5. 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.

  6. 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

  7. 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

  8. High-average-power, intense THz pulses from a LiNbO3 slab with silicon output coupler

    NASA Astrophysics Data System (ADS)

    Tsarev, M. V.; Ehberger, D.; Baum, P.

    2016-02-01

    Many applications of THz radiation require high fields and high repetition rates at the same time, implying substantial average power levels. Here, we report high-power Cherenkov-type THz generation in a LiNbO3 slab covered with a silicon prism outcoupler, a geometry in which the ratio between heat-removing surfaces and pump volume is naturally maximized for facilitating heat removal. At a conversion efficiency of 0.04 %, we achieve ~100 times more output power than before with such geometry. Although about 10 % of the 15 W pump power is converted to heat via multi-photon absorption effects, the peak crystal temperature increases by only 8 K. This result is due to the focus' extreme aspect ratio of ~100, indicating the scalability of the approach to even higher average power levels. A line-shaped focus should be advantageous for removing heat in other optical conversions as well.

  9. 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).

  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. Improved light output power of LEDs with embedded air voids structure and SiO2 current blocking layer

    NASA Astrophysics Data System (ADS)

    Zhou, Shengjun; Yuan, Shu; Liu, Sheng; Ding, Han

    2014-06-01

    GaN-based light-emitting diodes (LEDs) with an embedded air voids structure and a SiO2 current blocking layer (CBL) was fabricated and investigated. The air voids structure was formed between cone-shaped patterned sapphire substrate and GaN epitaxial layer by combining laser scribing with H3PO4-based hot chemical etching. The air voids embedded high power LED showed 8.9% higher light output power due to a strong light reflection and redirection at the interface between GaN and air voids, which could increase the top light extraction of the high power LED. Compared to the air voids embedded high power LED, the light output power of the high power LED by integrating air voids structure with SiO2 CBL was 9.1% higher than that of the air voids embedded LED without SiO2 CBL. It was also found that the simulation results agree well with the experimental results.

  12. 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. PMID:21934524

  13. 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.

  14. 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

  15. Output power enhancement of GaN light emitting diodes with p-type ZnO hole injection layer

    NASA Astrophysics Data System (ADS)

    Kim, B. J.; Ryu, Y. R.; Lee, T. S.; White, H. W.

    2009-03-01

    We report an enhancement of the optical output power of GaN light emitting diodes (LEDs) by addition of a p-type ZnO layer located in close proximity to the active layer (ZnO/GaN LEDs). Arsenic (As)-doped p-ZnO was used as a hole-injecting layer to overcome the drop in external quantum efficiency of GaN LEDs at high drive currents—the so-called "efficiency droop." The output power in ZnO/GaN LEDs was improved up to 40%. This result is useful for development of highly efficient GaN LEDs operating at high current densities that will play a critical role in replacement of incandescent lamps by high efficiency solid-state light bulbs.

  16. 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.

  17. 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.

  18. 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. PMID:17024643

  19. Maximizing Power Output in Homogeneous Charge Compression Ignition (HCCI) Engines and Enabling Effective Control of Combustion Timing

    NASA Astrophysics Data System (ADS)

    Saxena, Samveg

    Homogeneous Charge Compression Ignition (HCCI) engines are one of the most promising engine technologies for the future of energy conversion from clean, efficient combustion. HCCI engines allow high efficiency and lower CO2 emission through the use of high compression ratios and the removal of intake throttle valves (like Diesel), and allow very low levels of urban pollutants like nitric oxide and soot (like Otto). These engines, however, are not without their challenges, such as low power density compared with other engine technologies, and a difficulty in controlling combustion timing. This dissertation first addresses the power output limits. The particular strategies for enabling high power output investigated in this dissertation focus on avoiding five critical limits that either damage an engine, drastically reduce efficiency, or drastically increase emissions: (1) ringing limits, (2) peak in-cylinder pressure limits, (3) misfire limits, (4) low intake temperature limits, and (5) excessive emissions limits. The research shows that the key factors that enable high power output, sufficient for passenger vehicles, while simultaneously avoiding the five limits defined above are the use of: (1) high intake air pressures allowing improved power output, (2) highly delayed combustion timing to avoid ringing limits, and (3) using the highest possible equivalence ratio before encountering ringing limits. These results are revealed by conducting extensive experiments spanning a wide range of operating conditions on a multi-cylinder HCCI engine. Second, this dissertation discusses strategies for effectively sensing combustion characteristics on a HCCI engine. For effective feedback control of HCCI combustion timing, a sensor is required to quantify when combustion occurs. Many laboratory engines use in-cylinder pressure sensors but these sensors are currently prohibitively expensive for wide-scale commercialization. Instead, ion sensors made from inexpensive sparkplugs

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

    DOE PAGESBeta

    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

  1. 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.

  2. 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.

  3. 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%.

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

    PubMed Central

    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. PMID:24616703

  5. 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

  6. Short cladding-pumped Er/Yb phosphate fiber laser with 1.5 W output power

    SciTech Connect

    Li, L.; Morrell, M.; Qiu, T.; Temyanko, V.L.; Schuelzgen, A.; Mafi, A.; Kouznetsov, D.; Moloney, J.V.; Luo, T.; Jiang, S.; Peyghambarian, N.

    2004-10-04

    We report experimental results on a high-power, cladding-pumped, heavily Er/Yb co-doped phosphate fiber laser of very short length. Up to 1.5 W cw laser power was obtained from an11-cm-long multimode-core active fiber with optimized input and output couplers, when pumped by a 15 W diode laser at 975 nm. The fiber laser was demonstrated at 1535 nm with a linewidth <1.2 nm, and a good beam quality of M{sup 2}<3.

  7. 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.

  8. 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.

  9. 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

  10. Calorimetric output power measurements on a CW 20 kW 7.16 GHz microwave transmitter

    NASA Technical Reports Server (NTRS)

    Perez, Raul M.; Conroy, Bruce L.

    1991-01-01

    A calorimetric measurement technique developed for NASA's Deep Space Network (DSN) transmitters that does not require data on the coolant's thermal parameters is described. Calibration of the measurement system is achieved by measuring the DC input power to the klystron and relating coolant temperature increases to this known power dissipation. Agreement between calorimetric and electrical measurements of total system power was good, the difference being less than 2 percent. The operation of the system was not greatly affected by the composition of the coolant, which was varied from pure water to 40 percent ethylene glycol by mass. Good accuracy was also shown at output power levels, which varied over a 3.6:1 range.

  11. Thin-disk multipass amplifier for ultrashort laser pulses with kilowatt average output power and mJ pulse energies

    NASA Astrophysics Data System (ADS)

    Negel, Jan-Philipp; Voss, Andreas; Abdou Ahmed, Marwan; Bauer, Dominik; Sutter, Dirk; Killi, Alexander; Graf, Thomas

    2014-05-01

    We report on a Yb:YAG thin-disk multipass amplifier for ultrashort laser pulses delivering an average output power of 1.1 kW which to the best of our knowledge is the highest output power reported from such a system so far. A modified commercial TruMicro5050 laser delivers the seed pulses with an average power of 80 W at a wavelength of 1030 nm, a pulse duration of 6.5 ps and a repetition rate of 800 kHz. These pulses are amplified to 1.38 mJ of pulse energy with a duration of 7.3 ps. To achieve this, we developed a scheme in which an array of 40 plane mirrors is used to geometrically fold the seed beam over the pumped thin-disk crystal. Exploiting the incoming linear polarization, an overall number of 40 double-passes through the disk was realized by using the backpath through the amplifier with the orthogonal linear polarization state. Thermal issues on the disk were mitigated by zero-phonon line pumping at a wavelength of 969 nm directly into the upper laser level and by employing a retroreflective mirror pair. The amplifier exhibits an optical efficiency of 44 % and a slope efficiency of 46 %. The beam quality was measured to be better than M2=1.25 at all power levels. As this system can deliver high pulse energies and high average output powers at the same time without the need of a CPA technique, it can be very suitable for high productivity material processing with ultrashort laser pulses.

  12. Features of Propagation of the Acoustic-Gravity Waves Generated by High-Power Periodic Radiation

    NASA Astrophysics Data System (ADS)

    Chernogor, L. F.; Frolov, V. L.

    2013-09-01

    We present the results of the bandpass filtering of temporal variations of the Doppler frequency shift of radio signals from a vertical-sounding Doppler radar located near the city of Kharkov when the ionosphere was heated by high-power periodic (with 10 and 15-min periods) radiation from the Sura facility. The filtering was done in the ranges of periods that are close to the acoustic cutoff period and the Brunt—Väisälä period (4-6, 8-12, and 13-17 min). Oscillations with periods of 4-6 min and amplitudes of 50-100 mHz were not recorded in fact. Oscillations with periods of 8-12 and 13-17 min and amplitudes of 60-100 mHz were detected in almost all the sessions. In the former and the latter oscillations, the time of delay with respect to the heater switch-on was close to 100 min and about 40-50 min, respectively. These values correspond to group propagation velocities of about 160 and 320-400 m/s. The Doppler shift oscillations were caused by the acoustic-gravity waves which led to periodic variations in the electron number density with a relative amplitude of about 0.1-1.0%. It was demonstrated that the acoustic-gravity waves were not recorded when the effective power of the Sura facility was equal to 50 MW and they were confidently observed when the effective power was increased up to 130 MW. It is shown that the period of the wave processes was determined by the period of the heating-pause cycles, and the duration of the wave trains did not depend on the duration of the series of heating-pause cycles. The data suggest that the generation mechanism of recorded wave disturbances is different from the mechanism proposed in 1970-1990.

  13. Intermodulation components in the transmitter RF output due to high voltage power supply ripple

    NASA Technical Reports Server (NTRS)

    Finnegan, E. J.

    1977-01-01

    The economic feasibility of eliminating the 400-Hz motor-generator sets used to provide power to the high-voltage power supplies of the 20-kW transmitters and replace them with a 60-Hz high-voltage power supply was investigated. The efficiency of a power supply that runs from the 60-Hz line directly would pay for itself in about seven years and could be designed so that the transmitter would meet all the incidental phase and amplitude modulation specifications.

  14. Dust-acoustic waves and stability in the permeating dusty plasma. II. Power-law distributions

    SciTech Connect

    Gong Jingyu; Du Jiulin; Liu Zhipeng

    2012-08-15

    The dust-acoustic waves and the stability theory for the permeating dusty plasma with power-law distributions are studied by using nonextensive q-statistics. In two limiting physical cases, when the thermal velocity of the flowing dusty plasma is much larger than, and much smaller than the phase velocity of the waves, we derived the dust-acoustic wave frequency, the instability growth rate, and the instability critical flowing velocity. As compared with the formulae obtained in part I [Gong et al., Phys. Plasmas 19, 043704 (2012)], all formulae of the present cases and the resulting plasma characteristics are q-dependent, and the power-law distribution of each plasma component of the permeating dusty plasma has a different q-parameter and thus has a different nonextensive effect. Further, we make numerical analyses of an example that a cometary plasma tail is passing through the interplanetary space dusty plasma and we show that these power-law distributions have significant effects on the plasma characteristics of this kind of plasma environment.

  15. 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.

  16. 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.

  17. 785-nm dual wavelength DBR diode lasers and MOPA systems with output powers up to 750 mW

    NASA Astrophysics Data System (ADS)

    Sumpf, Bernd; Maiwald, Martin; Klehr, Andreas; Müller, André; Bugge, Frank; Fricke, Jörg; Ressel, Peter; Erbert, Götz; Tränkle, Günther

    2015-03-01

    Raman lines are often superimposed by daylight, artificial light sources or fluorescence signals from the samples under study. Shifted excitation Raman difference spectroscopy (SERDS), i.e. exciting the sample alternatingly with two slightly shifted wavelengths, allows to distinguish between the Raman lines and sources of interference. In this work, monolithic dual wavelength Y-branch DBR ridge waveguide diode lasers and their application in master oscillator power amplifier (MOPA) systems at 785 nm suitable for Raman spectroscopy and SERDS will be presented. The definition of the wavelengths is made by implementing deeply-etched 10th order 500 μm long surface gratings with different periods using i-line wafer stepper lithography. Y-branch DBR lasers with a total length of 3 mm and a stripe width of 2.2 μm were manufactured and characterized. The monolithic devices reach output powers up to 215 mW with emission widths of about 20 pm. At 200 mW the conversion efficiency is 20%, i.e. the electrical power consumption is only 1 W. The spectral distance between the two laser cavities is about 0.6 nm, i.e. 10 cm-1 as targeted. The side mode suppression ratio is better than 50 dB. Amplifying these devices using a ridge waveguide amplifier an output power of about 750 mW could be achieved maintaining the spectral properties of the master oscillator.

  18. 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,...

  19. 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…

  20. Diode-laser-pumped tunable 896-939.5-nm neodymium-doped fiber laser with 43-mW output power.

    PubMed

    Cook, A L; Hendricks, H D

    1998-05-20

    A diode-laser-pumped neodymium-doped fiber laser is presented. For a launched pump power of 85 mW, the fiber laser had a cw output power of 43 mW, which is approximately an order of magnitude greater output power than any previously reported diode-pumped neodymium fiber laser operating on the 4F(3/2)-4I(9/2) transition, which covers the 900-950-nm region. The fiber laser had a threshold power of 10 mW and a slope efficiency of 58% with respect to launched pump power. Tuning with a diffraction grating was obtained from 896 to 937 nm with narrow-band output powers as high as 32 mW. Emission was also obtained at 939.5 nm with use of a fiber Bragg grating as the output reflector. PMID:18273282

  1. Demonstration of a high power 1.5344 μm output Nd:YAG pumped OPO

    NASA Astrophysics Data System (ADS)

    Wojcik, Michael D.; Foltynowicz, Robert J.

    2011-03-01

    A high output power, eye-safe, lidar transmitter based on a KTA optical parametric oscillator (OPO) was demonstrated. The OPO was based on a two crystal, doubly resonant, non-critically phase-matched, KTA ring cavity. An injection seeded, 7ns, 30Hz, flashlamp-pumped, Q-switched Nd:YAG laser was used to pump the OPO. The OPO converted the 1064nm pump beam into a 1533nm signal wave and 3475nm idler wave. In addition to demonstrating a high power OPO system, we investigated the effects of seeding the pump laser on the OPO's conversion efficiency, oscillation threshold, maximum signal power, and beam quality. The power conversion efficiency between the signal and the injection seeded pump was 22% with an oscillation threshold of 104MW/cm2 (500mJ) and a maximum signal power of 6.44W (215mJ). The power conversion efficiency between the signal and the unseeded pump was 24% with an oscillation threshold of 77MW/cm2 (367mJ) and a maximum signal power of >7W (243mJ). When the pump laser was seeded, the full angle divergence improved by nearly a factor of five.

  2. 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.

  3. 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.

  4. 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

  5. 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.

  6. 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.

  7. 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.

  8. Efficacy of Er,Cr:YSGG Laser in Removing Smear Layer and Debris with Two Different Output Powers

    PubMed Central

    Bolhari, Behnam; Ehsani, Sara; Etemadi, Ardavan; Shafaq, Mohammad

    2014-01-01

    Abstract Objective: The purpose of this study was to evaluate the effectiveness of the erbium, chromium: yttrium-scandium-gallium-garnet (Er,Cr:YSGG) laser in removing debris and the smear layer using two different output powers on the apical, middle, and coronal segments of root canal walls. Background data: Previous literature has failed to evaluate the exclusive effect of Er,Cr:YSGG laser on the quality of smear layer and debris removal in all three segments of the root canal space. Methods: Sixty extracted teeth were included in the study. After instrumentation, samples were divided into three experimental groups and one positive control group with no further treatment. In group 1, a final irrigation was performed using ethylenediaminetetraacetic acid (EDTA) and sodium hypochlorite (NaOCl), sequentially. In group 2, the samples were treated with a 2.78 μm Er,Cr:YSGG laser with an output power of 1.5 W. The same laser was used in group 3, but with an output power of 2.5 W. Scanning electron microscope (SEM) images from the coronal, middle, and apical thirds of the roots were prepared and evaluated for both smear layer and debris removal by three blinded observers. Results: The results showed no differences between groups 1 and 2 regarding the quality of smear layer removal in all areas. However, the 2.5 W laser failed to remove the smear layer effectively. Regarding debris removal, the EDTA and NaOCl irrigation showed significantly better outcomes (adjusted p<0.05) in all areas. Conclusions: This study raises questions about the overall cleaning abilities of Er,Cr:YSGG lasers. PMID:25198390

  9. Single-frequency fiber oscillator with watt-level output power using photonic crystal phosphate glass fiber.

    PubMed

    Schülzgen, A; Li, L; Temyanko, V L; Suzuki, S; Moloney, J V; Peyghambarian, N

    2006-08-01

    Utilizing phosphate glass fiber with photonic crystal cladding and highly doped, large area core a cladding-pumped, single-frequency fiber oscillator is demonstrated. The fiber oscillator contains only 3.8 cm of active fiber in a linear cavity and operates in the 1.5 micron region. Spectrally broad, multimode pump light from semiconductor laser diodes is converted into a single-mode, single-frequency light beam with an efficiency of about 12% and the oscillator output power reached 2.3 W. PMID:19529079

  10. High-current pulsed electron accelerator “Gamma-1” with output power up to 1.5 TW

    NASA Astrophysics Data System (ADS)

    Zavyalov, N. V.; Gordeev, V. S.; Punin, V. T.; Grishin, A. V.; Myskov, G. A.; Nazarenko, S. T.; Mikhailov, E. S.; Kalashnikov, D. A.; Kozachek, A. V.; Pavlov, V. S.; Strabykin, K. V.; Glushkov, S. L.; Puchagin, S. Yu.; Mayornikova, V. L.; Mayorov, R. A.; Moiseevskikh, M. A.

    2014-08-01

    A multi-module multi-terawatt electrophysical facility “Gamma” is being developed at RFNCVNIIEF, Sarov, Russia. The facility will be used for conducting experiments in different fields of radiation physics. The first module of the facility - a high-current electron accelerator “Gamma-1” has been created. The output electric parameters of the module are as follows: electron energy ≤2.0 MeV, diode current 0.75 MA, maximal electric power 1.5 TW. Description of accelerator design and principles of its operation are presented. Results of experiments as well as further prospects on building a full-scale facility are given.

  11. 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.

  12. 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.

  13. 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.

  14. 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.

  15. 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.

  16. 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.

  17. 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.

  18. 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.

  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. Concentrating PV module output power using a wireless microcontroller based automatic sun tracker

    NASA Astrophysics Data System (ADS)

    Abou-Elnour, Ali; Salem, Asma M.; Ghanem, Salma M.; Ali, Iman

    2015-09-01

    In the present work, a wireless two dimensional microcontroller based sun tracker is designed and implemented. The proposed system has three main components namely the controlling unit, the wireless communication system, and the monitoring and recording unit. Controlling features are fully obtained in the present system using an efficient microcontroller based programming environment. Design equations, which are implemented, allow the usage of the system anywhere anytime without extra hardware tracking circuits. The sun tracker continuously calculates the photovoltaic module's tilt and azimuth angles by using accurate sun movement equations. The system generates the motors controlling signals to allocate the photovoltaic module to receive the maximize amount of solar energy on its surface from sunrise to sunset. For monitoring purpose the output of the movable photovoltaic module and from a south faced fixed module are wirelessly transmitted to the local monitoring system where the data are recorded, analyzed, and published. The proposed system is successfully implemented and tested for long periods under realistic operating conditions and the obtained positioning results are in excellent agreement with the theoretical ones.

  1. Analysis of Upper Bound Power Output for a Wrist-Worn Rotational Energy Harvester from Real-World Measured Inputs

    NASA Astrophysics Data System (ADS)

    Xue, T.; Ma, X.; Rahn, C.; Roundy, S.

    2014-11-01

    Energy harvesting from human motion addresses the growing need for battery-free health and wellness sensors in wearable applications. The major obstacles to harvesting energy in such applications are low and random frequencies due to the nature of human motion. This paper presents a generalized rotational harvester model in 3 dimensions to determine the upper bound of power output from real world measured data. Simulation results indicate much space for improvement on power generation comparing to existing devices. We have developed a rotational energy harvester for human motion that attempts to close the gap between theoretical possibility and demonstrated devices. Like previous work, it makes use of magnetically plucked piezoelectric beams. However, it more fully utilizes the space available and has many degrees of freedom available for optimization. Finally we present a prototype harvester based on the coupled harvester model with preliminary experimental validation.

  2. 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

  3. 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.

  4. Characteristics and reliability of high power multi-mode InGaAs strained quantum well single emitters with CW output powers of over 5W

    NASA Astrophysics Data System (ADS)

    Sin, Yongkun; Presser, Nathan; Mason, Maribeth; Moss, Steven C.

    2006-02-01

    High-power multi-mode broad area InGaAs strained quantum well (QW) single emitters (λ ~ 920-980nm) have been mainly used for industrial applications. Recently, these broad area lasers with CW output powers >5W have also found applications in communications as pump lasers for Er-Yb co-doped fiber amplifiers. This application requires very demanding characteristics including higher reliability than industrial applications. In contrast to 980nm single mode InGaAs strained QW lasers that are widely employed in both terrestrial and submarine applications, the fact that multimode lasers have never been used in optical communications necessitates careful study of these lasers. We report investigations of performance characteristics, reliability, and failure modes of high-power multi-mode single emitters. The lasers studied were broad area strained InGaAs-GaAs single QW lasers grown either by MOCVD or MBE. Typical apertures were around 100μm wide and cavity lengths were <=4.2mm. AR-HR coated laser diode chips were mounted on carriers with junction down configuration to reduce thermal impedance. Laser thresholds were <=453mA at RT. At 6A injection current typical CW output powers were over 5W at 25°C with wall-plug efficiency of ~60%. Characteristics measured included thermal impedance and optical beam profiles that are critical in understanding performance and reliability. Automatic current control burn-in tests with different stress conditions were performed and log (I)-V characteristics were measured at RT to correlate degradation in optical output power and an increase in trap density estimated from the 2κ•T term in bulk recombination current. We also report initial analysis of lifetest results and failure modes from these lasers.

  5. 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. PMID:16094361

  6. Acoustic waveguide technique for sensing incipient faults in underground power-transmission cables: including acousto-optic techniques. Final report

    SciTech Connect

    Harrold, R.T.

    1981-09-01

    The feasibility of using acoustic waveguide techniques for sensing incipient faults in underground power transmission cables was determined. Theoretical and practical studies were made of both the acoustic emission spectrum signatures associated with cable incipient faults, and the attenuation of acoustic waves in waterfilled metal tubes used as waveguides. Based on critical data, it can be estimated that in favorable circumstances, the acoustic waveguide system would only be useful for sensing incipient faults in underground cables of approx. 800 meters (approx. 0.5 miles) or less in length. As underground power transmission cables are often several kilometers in length, it was clear at this stage of the study, that simple acoustic waveguide sensing techniques would not be adequate, and some modification would be needed. With DOE approval it was decided to investigate acousto-optic sensing techniques in order to extend the detection range. In particular, a system in which acoustic emissions from cable incipient faults impinge on a fiber-optic lightguide and locally change its refractive indes, and as a consequence, modulate laser light transmitted along the light guide. Experiments based on this concept were successful, and it has been demonstrated that it is possible to sense acoustic emissions with energy levels below one micro-joule. A practical test of this system in the laboratory using a section of compressed gas-insulated cable with an internal flashover was successfully carried out. Long distance fault sensing with this technique should be feasible as laser light can be transmitted several kilometers in fiber optic lightguides. It is believed that laser-acousto-optic fault sensing is a viable technique which, with development, could be applied for fault sensing in power cables and other apparatus.

  7. 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

  8. Modeling and simulation of output power of a high-power He-SrBr2 laser by using multivariate adaptive regression splines

    NASA Astrophysics Data System (ADS)

    Iliev, I. P.; Gocheva-Ilieva, S. G.

    2013-02-01

    Due to advancement in computing technology researchers are focusing onto novel predictive models and techniques for improving the design and performance of the devices. This study examines a recently developed high-powered SrBr2 laser excited in a nanosecond pulse longitudinal He-SrBr2 discharge. Based on the accumulated experiment data, a new approach is proposed for determining the relationship between laser output power and basic laser characteristics: geometric design, supplied electric power, helium pressure, etc. Piece-wise linear and nonlinear statistical models have been built with the help of the flexible predictive MARS technique. It is shown that the best nonlinear MARS model containing second degree terms provides the best description of the examined data, demonstrating a coefficient of determination of over 99%. The resulting theoretical models are used to estimate and predict the experiment as well as to analyze the local behavior of the relationships between laser output power and input laser characteristics. The second order model is applied to the design and optimization of the laser in order to enhance laser generation.

  9. 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.

  10. 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.

  11. 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.

  12. 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

  13. 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

  14. Reproducibility of peak power output during a 10-s cycling maximal effort using different sampling rates.

    PubMed

    Duarte, J P; Coelho-E-Silva, Manuel J; Severino, V; Martinho, D; Luz, L; Pereira, J R; Baptista, R; Valente-Dos-Santos, J; Machado-Rodrigues, A M; Vaz, V; Cupido-Dos-Santos, A; Martín-Hernández, J; Cumming, S P; Malina, R M

    2014-12-01

    The study was aimed to investigate the reproducibility of performance parameters obtained from 10-s maximal cycling effort against different braking forces in young adult athletes. The sample (n = 48) included male athletes aged 18.9-29.9 years (175.5 ± 6.9 cm, 76.2 ± 10.1 kg). The exercise protocol was performed in a cycle-ergometer against a random braking force (4% to 11% of body mass). Intra-individual variation was examined from repeated tests within one week. Descriptive statistics were computed and differences between sessions were tested using paired t-test. The coefficient of correlation between repeated measures, technical error of measurement (TEM), coefficient of variation and ICC were calculated. Agreement between trials was examined using the Bland-Altman procedure. Mean values of peak power were relatively stable when obtained from sampling rates of 50 Hz and ranged between 1068 watt and 1082 watt (t(47) = 1.149, p = 0.256, ES-r = 0.165) or while corresponding to a sampling rate of 1 Hz (t(47) = 0.742, p = 0.462, ES-r = 0.107). Correlations between repeated measures were high (+0.907, 95% CI: +0.839 to +0.947) and TEM about 59.3 watt (%CV = 5.52%; ICC = 0.951, 95% CI: 0.912 to 0.972). The present study suggests that reproducibility of peak power in male adult athletes tended to be acceptable and within individual error appeared unrelated to braking force. PMID:25201712

  15. Simulation of Acoustic Noise Generated by an Airbreathing, Beam-Powered Launch Vehicle

    NASA Astrophysics Data System (ADS)

    Kennedy, W. C.; Van Laak, P.; Scarton, H. A.; Myrabo, L. N.

    2005-04-01

    A simple acoustic model is developed for predicting the noise signature vs. power level for advanced laser-propelled lightcraft — capable of single-stage flights into low Earth orbit. This model predicts the noise levels generated by a pulsed detonation engine (PDE) during the initial lift-off and acceleration phase, for two representative `tractor-beam' lightcraft designs: a 1-place `Mercury' vehicle (2.5-m diameter, 900-kg); and a larger 5-place `Apollo' vehicle (5-m diameter, 5555-kg) — both the subject of an earlier study. The use of digital techniques to simulate the expected PDE noise signature is discussed, and three examples of fly-by noise signatures are presented. The reduction, or complete elimination of perceptible noise from such engines, can be accomplished by shifting the pulse frequency into the supra-audible or sub-audible range.

  16. 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.

  17. Lithium-Ion Ultracapacitors integrated with Wind Turbines Power Conversion Systems to Extend Operating Life and Improve Output Power Quality

    SciTech Connect

    Adel Nasiri

    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.

  18. 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.

  19. 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.

  20. 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.

  1. Small scale aspects of warm dark matter: Power spectra and acoustic oscillations

    SciTech Connect

    Boyanovsky, Daniel; Wu Jun

    2011-02-15

    We provide a semianalytic derivation of approximate evolution equations for density perturbations of warm dark matter candidates that decoupled while relativistic with arbitrary distribution functions, their solutions at small scales, and a simple numerical implementation that yields their transfer functions and power spectra. Density perturbations evolve through three stages: radiation domination when the particle is relativistic and nonrelativistic and matter domination. An early integrated Sachs-Wolfe effect during the first stage leads to an enhancement of density perturbations and a plateau in the transfer function for k < or approx. k{sub fs}, the free-streaming wave vector. An effective fluid description emerges at small scales which includes the effects of free streaming in initial conditions and inhomogeneities. The transfer function features warm dark matter acoustic oscillations at scales k > or approx. 2k{sub fs}. A simple analytic interpolation of the power spectra between large and small scales and a numerical implementation valid for arbitrary distribution functions is provided. As an application we study the power spectra for two models of sterile neutrinos with m{approx}keV produced nonresonantly and compare our results to those obtained from Boltzmann codes.

  2. 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

  3. Influence of patterned sapphire substrates with different symmetry on the light output power of InGaN-based LEDs.

    PubMed

    You, Yao-Hong; Su, Vin-Cent; Ho, Ti-En; Lin, Bo-Wen; Lee, Ming-Lun; Das, Atanu; Hsu, Wen-Ching; Kuan, Chieh-Hsiung; Lin, Ray-Ming

    2014-01-01

    This paper aims to investigate the light output power (LOP) of InGaN-based light-emitting diodes (LEDs) grown on patterned sapphire substrates (PSSs) with different symmetry. The GaN epitaxial layers grown on the hexagonal lattice arrangement PSS (HLAPSS) have a lower compressive strain than the ones grown on the square lattice arrangement PSS (SLAPSS). The quantum-confined Stark effect (QCSE) is also affected by the residual compressive strain. Based on the experimentally measured data and the ray tracing simulation results, the InGaN-based LED with the HLAPSS has a higher LOP than the one with the SLAPSS due to the weaker QCSE within multiple-quantum wells (MQWs). PMID:25392706

  4. Influence of patterned sapphire substrates with different symmetry on the light output power of InGaN-based LEDs

    PubMed Central

    2014-01-01

    This paper aims to investigate the light output power (LOP) of InGaN-based light-emitting diodes (LEDs) grown on patterned sapphire substrates (PSSs) with different symmetry. The GaN epitaxial layers grown on the hexagonal lattice arrangement PSS (HLAPSS) have a lower compressive strain than the ones grown on the square lattice arrangement PSS (SLAPSS). The quantum-confined Stark effect (QCSE) is also affected by the residual compressive strain. Based on the experimentally measured data and the ray tracing simulation results, the InGaN-based LED with the HLAPSS has a higher LOP than the one with the SLAPSS due to the weaker QCSE within multiple-quantum wells (MQWs). PMID:25392706

  5. 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

  6. Air-Hybrid Distributed Bragg Reflector Structure for Improving the Light Output Power in AlGalnP-Based LEDs.

    PubMed

    Oh, Hwa Sub; Ryu, Ho-Soung; Park, Sueng Ho; Jeong, Tak; Kim, Young Jin; Lee, Hyung Joo; Cho, Young Dae; Kwak, Joon-Seop; Baek, Jong Hyeob

    2015-07-01

    We investigated air gap-induced hybrid distributed Bragg reflectors (AH-DBRs) for use in high brightness and reliable AlGalnP-based light emitting diodes (LEDs). An air gap was inserted into the side of DBRs by selectively etching the Al(x),Ga1-xAs DBR structures. With the AH-DBR structures, the optical output power of LEDs was enhanced by 15% compared to LEDs having conventional DBRs, due to the effective reflection of obliquely incident light by the air gap structures. In addition, the electrical characteristics showed that the AH-DBR LED is a desirable structure for reducing the leakage current, as it suppresses unwanted surface recombinations. PMID:26373075

  7. 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

  8. 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.

  9. A high-temperature acoustic-electric system for power delivery and data communication through thick metallic barriers

    NASA Astrophysics Data System (ADS)

    Lawry, T. J.; Wilt, K. R.; Roa-Prada, S.; Ashdown, J. D.; Saulnier, G. J.; Scarton, H. A.; Das, P. K.; Gavens, A. J.

    2011-06-01

    In many sensing applications that monitor extreme environmental conditions within sealed metallic vessels, penetrating vessel walls in order to feed through power and data cables is impractical, as this may compromise a vessels structural integrity and its environmental isolation. Frequent servicing of sensing equipment within these environments is costly, so the use of batteries is strongly undesired and power harvesting techniques are preferred. Traditional electromagnetic power delivery and communication techniques, however, are highly ineffective in these applications, due to Faraday shielding effects from the metallic vessel walls. A viable, non-destructive alternative is to use piezoelectric materials to transmit power through thick metallic barriers acoustically. We present critical elements of a high-temperature battery-less sensor system prototype, including power harvesting, voltage regulation, and data communication circuitry able to operate up to 260°C. Power transmission is achieved by coaxially aligning a pair of high-temperature piezoelectric transducers on opposite sides of a thick steel barrier. Continuous-wave excitation of the outside transducer creates an acoustic beam that is captured by the opposite transducer, forming an acoustic-electric link for power harvesting circuitry. Simultaneously, sensor data can be transmitted out of the high-temperature environment by switching the electrical impedance placed across the leads of the inside transducer, creating a reflection-based amplitude modulated signal on the outside transducer. Transducer housing, loading, and alternatives for acoustic couplants are discussed. Measurement results are presented, and it was found that the system can harvest up to 1 watt of power and communicate sensor data up to 50 kbps, while operating at 260°C.

  10. Calculating room acoustic parameters from pseudo-impulsive acoustic sources

    NASA Astrophysics Data System (ADS)

    San Martin, Maria L.; Vela, Antonio; San Martin, Ricardo; Arana, Miguel A.

    2002-11-01

    The impulse response function provides complete information to predict the acoustic response of a room to an acoustic input of arbitrary characteristics. At this job study, small explosions of firecrackers are proposed to be used as pseudo-impulsive acoustics sources to determine some acoustic parameters of a room such as reverberation time, definition, and clarity, comparing these results to those obtained with other techniques. A previous characterization of these sources allows us to state that they can be used for this purpose because they are, in practice, omnidirectional, their temporary pattern is highly repetitive and their spectral power is, as well, repetitive and with enough power in octave bands from 125 Hz to 8 kHz. If the linear time-invariant system impulse response h(t) is known, output signal s(t) regarding any arbitrary signal s(t) can be obtained. For our pseudo-impulsive sources, the output signal s(t) has been taken as impulse response h(t). Using the integrated impulse response method suggested by Schroeder, it has been stated that both the mean values and standard deviations for some parameters are practically identical to results obtained with other usual techniques. (To be presented in Spanish.)

  11. Influence of Forecast Accuracy of Photovoltaic Power Output on Facility Planning and Operation of Microgrid under 30 min Power Balancing Control

    NASA Astrophysics Data System (ADS)

    Kato, Takeyoshi; Sone, Akihito; Shimakage, Toyonari; Suzuoki, Yasuo

    A microgrid (MG) is one of the measures for enhancing the high penetration of renewable energy (RE)-based distributed generators (DGs). For constructing a MG economically, the capacity optimization of controllable DGs against RE-based DGs is essential. By using a numerical simulation model developed based on the demonstrative studies on a MG using PAFC and NaS battery as controllable DGs and photovoltaic power generation system (PVS) as a RE-based DG, this study discusses the influence of forecast accuracy of PVS output on the capacity optimization and daily operation evaluated with the cost. The main results are as follows. The required capacity of NaS battery must be increased by 10-40% against the ideal situation without the forecast error of PVS power output. The influence of forecast error on the received grid electricity would not be so significant on annual basis because the positive and negative forecast error varies with days. The annual total cost of facility and operation increases by 2-7% due to the forecast error applied in this study. The impact of forecast error on the facility optimization and operation optimization is almost the same each other at a few percentages, implying that the forecast accuracy should be improved in terms of both the number of times with large forecast error and the average error.

  12. 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

  13. 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

  14. 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

  15. 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

  16. 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

  17. Violet InGaN/GaN/AlGaN-Based Laser Diodes with an Output Power of 420 mW

    NASA Astrophysics Data System (ADS)

    Nakamura, Shuji; Senoh, Masayuki; Nagahama, Shin-ichi; Iwasa, Naruhito; Yamada, Takao; Matsushita, Toshio; Kiyoku, Hiroyuki; Sugimoto, Yasunobu; Kozaki, Tokuya; Umemoto, Hitoshi; Sano, Masahiko; Chocho, Kazuyuki

    1998-06-01

    The InGaN multiquantum-well-structure laser diode (LD) was grown on epitaxially laterally overgrown GaN on sapphire. The LDs with cleaved mirror facets showed an output power as high as 420 mW per facet under room temperature continuous-wave (CW) operation. The fundamental transverse mode was observed up to an output power of 100 mW. The lifetime of the LDs at a constant output power of 30 mW was longer than 160 h under CW operation at an ambient temperature of 50°C. The wavelength drift caused by the temperature change was estimated to be 0.06 nm/K, while that of the red AlInGaP LDs was 0.3 nm/K.

  18. 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.

  19. All-solid-state continuous-wave frequency-doubling Nd:YVO(4)/LBO laser with 2.35 W output power at 543 nm.

    PubMed

    Yao, Yi; Zheng, Quan; Qu, Dapeng; Gong, Xiangyu; Zhou, Kai; Liu, Yang; Zhao, Ling

    2009-12-01

    Efficient and compact green-yellow laser output at 543 nm is generated by intracavity frequency doubling of a cw diode-pumped Nd:YVO(4) laser at 1086 nm under the condition of suppressing the higher gain transition near 1064 nm. With 14.5 W of diode pump power and the frequency-doubling crystal LiB(3)O(5), as high as 2.35 W of cw output power at 543 nm is achieved, corresponding to an optical-to-optical conversion efficiency of 15.7%; the output power stability over 5 h is better than 2.56%. 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:YVO(4) laser at 1086 nm. PMID:19953186

  20. 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.

  1. 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.

  2. 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.

  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. Temperature Measurements on Hot Spots of Power Substations Utilizing Surface Acoustic Wave Sensors

    NASA Astrophysics Data System (ADS)

    Cavaco, M. A. M.; Benedet, M. E.; Neto, L. R.

    2011-12-01

    In several applications in the field of metrology, the direct connection of the sensor element with the respective signal-processing unit of the measurement system is not trivial. It can be mentioned, as an example, the measurement of hot points in electric power substations because of the high electrical potential. To solve that problem, two alternatives were studied, one using active surface acoustic wave (SAW) sensors and other using passive SAW tags. For the passive sensor, a SAW radio-frequency identification (RFID) temperature detector was used. That technology is widely applied for typical transport identification (grain transportation, road traffic control), but its application in the field of metrology is innovative. The variation in temperature makes an alteration in the characteristics of the piezoelectric material of the SAW matrix, changing mostly the resonance frequency. Using SAW-RFID, the problem of measuring temperature basically is directed to the identification of the frequency of resonance of the SAW. The use of active SAW sensors has been demonstrated to be much more satisfactory for the solution of such a problem because of the limitation in the range of the passive sensors.

  5. DBR tapered diode laser with 12.7 W output power and nearly diffraction-limited, narrowband emission at 1030 nm

    NASA Astrophysics Data System (ADS)

    Müller, André; Fricke, Jörg; Bugge, Frank; Brox, Olaf; Erbert, Götz; Sumpf, Bernd

    2016-04-01

    A 1030 nm distributed Bragg reflector (DBR) tapered diode laser with nearly diffraction-limited emission is presented. The laser provides an optical output power of 12.7 W with an electro-optical efficiency >40 %. At 10.5 W of optical output power, a central lobe power content of 8.1 W and a nearly diffraction-limited beam propagation ratio of M 2 = 1.1 (1/ e 2) are obtained. The corresponding brightness is 700 MW cm-2 sr-1. Compared to previous approaches, intrinsic wavelength stabilization is obtained by a third-order DBR grating manufactured using more reproducible electron-beam lithography. A narrowband emission is measured over the whole power range with a spectral bandwidth of about 17 pm at 12.5 W. Based on the measured electro-optical, spectral and spatial properties, the laser is suitable for applications requiring narrowband, high-power emission with high spatial quality.

  6. A time-saving method to assess power output at lactate threshold in well-trained and elite cyclists.

    PubMed

    Støren, Øyvind; Rønnestad, Bent R; Sunde, Arnstein; Hansen, Joar; Ellefsen, Stian; Helgerud, Jan

    2014-03-01

    The purpose of this study was to examine the relationship between lactate threshold (LT) as a percentage of maximal oxygen consumption (V[Combining Dot Above]O2max) and power output at LT (LTW) and also to investigate to what extent V[Combining Dot Above]O2max, oxygen cost of cycling (CC), and maximal aerobic power (MAP) determine LTW in cycling to develop a new time-saving model for testing LTW. To do this, 108 male competitive cyclists with an average V[Combining Dot Above]O2max of 65.2 ± 7.4 ml·kg·min and an average LTW of 274 ± 43 W were tested for V[Combining Dot Above]O2max, LT %V[Combining Dot Above]O2max, LTW, MAP, and CC on a test ergometer cycle. The product of MAP and individual LT in %V[Combining Dot Above]O2max was found to be a good determinant of LTW (R = 0.98, p < 0.0001). However, LT in %V[Combining Dot Above]O2max was found to be a poor determinant of LTW (R = 0.39, p < 0.0001). Based on these findings, we have suggested a new time-saving method for calculating LTW in well-trained cyclists. The benefits from this model come both from tracking LTW during training interventions and from regularly assessing training status in competitive cyclists. Briefly, this method is based on the present findings that LTW depends on LT in %V[Combining Dot Above]O2max, V[Combining Dot Above]O2max, and CC and may after an initial test session reduce the time for the subsequent testing of LTW by as much as 50% without the need for blood samples. PMID:23942166

  7. Hybrid Solid Oxide Fuel Cell and Thermoelectric Generator for Maximum Power Output in Micro-CHP Systems

    NASA Astrophysics Data System (ADS)

    Rosendahl, L. A.; Mortensen, Paw V.; Enkeshafi, Ali A.

    2011-05-01

    One of the most obvious early market applications for thermoelectric generators (TEG) is decentralized micro combined heat and power (CHP) installations of 0.5 kWe to 5 kWe based on fuel cell technology. Through the use of TEG technology for waste heat recovery it is possible to increase the electricity production in micro-CHP systems by more than 15%, corresponding to system electrical efficiency increases of some 4 to 5 percentage points. This will make fuel cell-based micro-CHP systems very competitive and profitable and will also open opportunities in a number of other potential business and market segments which are not yet quantified. This paper quantifies a micro-CHP system based on a solid oxide fuel cell (SOFC) and a high-performance TE generator. Based on a 3 kW fuel input, the hybrid SOFC implementation boosts electrical output from 945 W to 1085 W, with 1794 W available for heating purposes.

  8. Effects of isokinetic training of the knee extensors on isometric strength and peak power output during cycling.

    PubMed

    Mannion, A F; Jakeman, P M; Willan, P L

    1992-01-01

    Isokinetic training of right and left quadriceps femoris was undertaken three times per week for 16 weeks. One group of subjects (n = 13) trained at an angular velocity of 4.19 rad.s-1 and a second group (n = 10) at 1.05 rad.s-1. A control group (n = 10) performed no training. Maximal voluntary contraction (MVC) of the quadriceps, and peak pedal velocity nu p,peak) and peak power output (Wpeak) during all-out cycling (against loads equivalent to 9, 10, 11, 12, 13 and 14% MVC) were assessed before and after training. The two training groups did not differ significantly from each other in their training response to any of the performance variables (P > 0.05). No significant difference in MVC was observed for any group after the 16-week period (P = 0.167). The post-training increases in average Wpeak (7%) and nu p,peak (6%) during the cycle tests were each significantly different from the control group response (P = 0.018 and P = 0.008, respectively). It is concluded that 16 weeks of isokinetic strength training of the knee extensors is able to significantly improve nu p, peak and Wpeak during spring cycling, an activity which demands considerable involvement of the trained muscle group but with its own distinct pattern of coordination. PMID:1425638

  9. An"ON-OFF" switchable power output of enzymatic biofuel cell controlled by thermal-sensitive polymer.

    PubMed

    Chen, Yun; Gai, Panpan; Xue, Jingjing; Zhang, Jian-Rong; Zhu, Jun-Jie

    2015-12-15

    A novel "ON-OFF" switchable enzymatic biofuel cell (EBFC), controlled by in situ thermal-stimuli signal, has been consciously designed. Poly (N-isopropylacrylamide) (PNIPAm) chains were used to act as "ON" and "OFF" channels. Consecutively switching of temperature below and above the lower critical solution temperature (LCST), the reversible conformation changing of the PNIPAm chains between superhydrophilicity and superhydrophobicity was achieved, which constructed the "ON" and "OFF" channel for the transfer of the electrochemical probe to the underlying electrode correspondingly. Gold nanoparticles (AuNPs) protected glucose oxidase and laccase were successfully entrapped into the intelligent thermal-sensitive PNIPAm chains, and performed as the catalysts for the oxidation of glucose and the reduction of O2, respectively. Below the LCST, the fuels and the mediator could access to the catalytic centers of enzymes (set as "ON" state); while above the LCST, the reaction was impeded because the process of reactant transmission was blocked (set as "OFF" state). By switching the "valve" of mass transfer, the fabricated EBFC displayed the obvious "ON-OFF" controllable behavior. At the "ON" state, the open circuit voltage (Ecell(ocv)) and maximal power output density (Pmax) could reach to 0.70 V and 20.52 μW cm(-2), respectively; while at the "OFF" state, the Ecell(ocv) and Pmax were only 0.30 V and 3.28 μW cm(-2) correspondingly. The switchable process was repeatable, and the response time was only several minutes. PMID:26141100

  10. 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

  11. Structure- and fluid-borne acoustic power sources induced by turbulent flow in 90° piping elbows

    NASA Astrophysics Data System (ADS)

    Hambric, S. A.; Boger, D. A.; Fahnline, J. B.; Campbell, R. L.

    2010-01-01

    The structure- and fluid-borne vibro-acoustic power spectra induced by turbulent fluid flow over the walls of a continuous 90° piping elbow are computed. Although the actual power input to the piping by the wall pressure fluctuations is distributed throughout the elbow, equivalent total power inputs to various structural wavetypes (bending, torsion, axial) and fluid (plane-waves) at the inlet and discharge of the elbow are computed. The powers at the elbow “ports” are suitable inputs to wave- and statistically-based models of larger piping systems that include the elbow. Calculations for several flow and structural parameters, including pipe wall thickness, flow speed, and flow Reynolds number are shown. The power spectra are scaled on flow and structural-acoustic parameters so that levels for conditions other than those considered in the paper may be estimated, subject to geometric similarity constraints (elbow radius/pipe diameter). The approach for computing the powers (called CHAMP - combined hydroacoustic modeling programs), which links computational fluid dynamics, finite element and boundary element modeling, and efficient random analysis techniques, is general, and may be applied to other piping system components excited by turbulent fluid flow, such as U-bends and T-sections.

  12. 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.

  13. The Acute Effect of Upper-Body Complex Training on Power Output of Martial Art Athletes as Measured by the Bench Press Throw Exercise

    PubMed Central

    Liossis, Loudovikos Dimitrios; Forsyth, Jacky; Liossis, Ceorge; Tsolakis, Charilaos

    2013-01-01

    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 eta2=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. PMID:24511352

  14. 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.

  15. Nd:GdVO4 self-Raman laser using double-end polarised pumping at 880 nm for high power infrared and visible output

    NASA Astrophysics Data System (ADS)

    Lin, J.; Pask, H. M.

    2012-07-01

    We report and evaluate a novel double-end polarised 880 nm pumping scheme for a Nd:GdVO4 self-Raman laser, aimed at efficiently generating high output powers in the near-infrared and visible. Compared to conventional single-end pumping, this pump scheme has significant benefits in terms of absorption efficiency, temperature effects in the crystal, and mode-matching between the pumping beam and TEM00 resonator mode. The maximum first-Stokes output powers were 4.1 W for CW operation and 5.63 W for quasi-CW (50 % duty-cycle) operation, with the diode-Stokes conversion efficiency of 11.2 % and 10.3 %, respectively. Visible emission was also realised by intra-cavity frequency-doubling (586.5 nm) or sum-frequency-generation (559 nm) using BBO or LBO crystals. For CW operation, the maximum output power was 3.46 W at 586.5 nm and 4.05 W at 559 nm, with diode-visible conversion efficiency of 10.7 % and 12.5 %; while for quasi-CW operation (50 % duty-cycle), the maximum output peak power was 6.5 W at 586.5 nm and 9.2 W at 559 nm, corresponding to 13.1 % and 18.9 % diode-visible conversion efficiency.

  16. 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

  17. Acoustic chaos

    SciTech Connect

    Lauterborn, W.; Parlitz, U.; Holzfuss, J.; Billo, A.; Akhatov, I.

    1996-06-01

    Acoustic cavitation, a complex, spatio-temporal dynamical system, is investigated with respect to its chaotic properties. The sound output, the {open_quote}{open_quote}noise{close_quote}{close_quote}, is subjected to time series analysis. The spatial dynamics of the bubble filaments is captured by high speed holographic cinematography and subsequent digital picture processing from the holograms. Theoretical models are put forward for describing the pattern formation. {copyright} {ital 1996 American Institute of Physics.}

  18. 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

  19. 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.

  20. 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

  1. 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…

  2. Design of Injection and Extraction at an 8-GeV Booster Ring and the J-PARC Main Ring for Multi-MW Output Beam Power

    NASA Astrophysics Data System (ADS)

    Harada, Hiroyuki; Hotchi, Hideaki; Igarashi, Susumu; Sato, Yoichi; Koseki, Tadashi

    The 240-kW output beam power in the MR has been achieved for a 30-GeV user operation with the repetition cycle of 2.48 sec and injecting proton beams of 380-kW equivalent intensity from RCS. The MR aims to realize 750-kW beam operation with faster repetition cycle of ˜1 s and injecting proton beams of 600-kW equivalent intensity from RCS. The MR is developing the new type power supplies of MR main magnets and high-impedance core of MR RF cavities toward faster repetition cycle. We are now exploring the further beam power upgrade scenario of the J-PARC accelerators. As one possible scenario toward a multi-MW output beam power from MR, a new 8-GeV booster ring (BR) between RCS and MR is also designed. The injection energy of the MR increases from present 3-GeV to 8-GeV. The higher injection energy of the MR would be able to mitigate a space charge force in MR injection energy region and secure the acceptance clearance of beam from MR physical aperture. In this paper, the designed injection and extraction system of BR are described. Additionally, a new concept of BR extraction and MR injection toward multi-MW output beam power are described.

  3. 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.

  4. All-solid-state continuous-wave frequency doubling Nd:LuVO4/LBO laser with 9.6 W output power at 672 nm

    NASA Astrophysics Data System (ADS)

    Li, B.; Zhao, L.; Zhang, Y. B.; Zheng, Q.; Zhao, Y.; Yao, Y.

    2012-12-01

    An efficient and compact red laser at 672 nm is generated by intracavity frequency doubling of a continuous wave (CW) laser operation of a diode pumped Nd:LuVO4 laser at 1344 nm under the condition of suppression the higher gain transition near 1064 nm. With 38 W diode pump power and a frequency doubling crystal LBO, as high as 9.6 W of CW output power at 672 nm is achieved, corresponding to an optical-to-optical conversion efficiency of 25.3% and the output power stability in 8 h is better than 2.38%. To the best of our knowledge, this it the highest conversion efficiency of watt-level laser at 672 nm generated by intracavity frequency doubling of a diode pumped Nd:LuVO4 laser at 1344 nm.

  5. All-solid-state continuous-wave frequency doubling Nd:LuVO4/LBO laser with 9.6 W output power at 458 nm

    NASA Astrophysics Data System (ADS)

    Li, B.; Zhao, L.; Zhang, Y. B.; Zheng, Q.; Zhao, Y.; Yao, Y.

    2013-02-01

    An efficient and compact red laser at 458 nm is generated by intracavity frequency doubling of a continuous wave (CW) laser operation of a diode pumped Nd:LuVO4 laser at 916 nm under the condition of suppression the higher gain transition near 1064 nm. With 30 W diode pump power and a frequency doubling crystal LBO, as high as 9.6 W of CW output power at 458 nm is achieved, corresponding to an optical-to-optical conversion efficiency of 32.0% and the output power stability in 8 hours is better than 2.35%. To the best of our knowledge, this it the highest conversion efficiency of watt-level laser at 458 nm generated by intracavity frequency doubling of a diode pumped Nd:LuVO4 laser at 916 nm.

  6. All-solid-state continuous-wave frequency doubling Nd:YAG/LBO laser with 8.2 W output power at 660 nm

    NASA Astrophysics Data System (ADS)

    Zhu, P. F.; Li, B.; Liu, W. Q.; Liu, T. H.; Fang, C. X.; Zhao, Y.; Zheng, Q.

    2012-11-01

    An efficient and compact red laser at 660 nm is generated by intracavity frequency doubling of continuous wave (CW) laser operation of a diode pumped Nd:YAG laser at 1319 nm under the condition of suppression the higher gain transition near 1064 and 1319 nm under the condition of suppression the higher gain transition near 1064 and 1338 nm. With 40 W diode pump power and a frequency doubling crystal LBO, as high as 8.6 W of CW output power at 660 nm is achieved, corresponding to an optical-to-optical conversion efficiency of 21.5% and the output power stability in 8 h is better than 2.73%. To the best of our knowledge, this it the highest conversion efficiency of watt-level laser at 660 nm generated by intracavity frequency doubling of a diode end pumped Nd:YAG laser at 1319 nm.

  7. 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.

  8. 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.

  9. 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

  10. Analyses of power output of piezoelectric energy-harvesting devices directly connected to a load resistor using a coupled piezoelectric-circuit finite element method.

    PubMed

    Zhu, Meiling; Worthington, Emma; Njuguna, James

    2009-07-01

    This paper presents, for the first time, a coupled piezoelectric-circuit finite element model (CPC-FEM) to analyze the power output of a vibration-based piezoelectric energy-harvesting device (EHD) when it is connected to a load resistor. Special focus is given to the effect of the load resistor value on the vibrational amplitude of the piezoelectric EHD, and thus on the current, voltage, and power generated by the device, which are normally assumed to be independent of the load resistor value to reduce the complexity of modeling and simulation. The presented CPC-FEM uses a cantilever with a sandwich structure and a seismic mass attached to the tip to study the following characteristics of the EHD as a result of changing the load resistor value: 1) the electric outputs: the current through and voltage across the load resistor; 2) the power dissipated by the load resistor; 3) the displacement amplitude of the tip of the cantilever; and 4) the shift in the resonant frequency of the device. It is found that these characteristics of the EHD have a significant dependence on the load resistor value, rather than being independent of it as is assumed in most literature. The CPC-FEM is capable of predicting the generated output power of the EHD with different load resistor values while simultaneously calculating the effect of the load resistor value on the displacement amplitude of the tip of the cantilever. This makes the CPC-FEM invaluable for validating the performance of a designed EHD before it is fabricated and tested, thereby reducing the recurring costs associated with repeat fabrication and trials. In addition, the proposed CPC-FEM can also be used for producing an optimized design for maximum power output. PMID:19574142

  11. 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

  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). PMID:12659270

  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. Surface free-carrier screening effect on the output of a ZnO nanowire nanogenerator and its potential as a self-powered active gas sensor.

    PubMed

    Xue, Xinyu; Nie, Yuxin; He, Bin; Xing, Lili; Zhang, Yan; Wang, Zhong Lin

    2013-06-01

    The output of a piezoelectric nanogenerator (NG) fabricated using ZnO nanowire arrays is largely influenced by the density of the surface charge carriers at the nanowire surfaces. Adsorption of gas molecules could modify the surface carrier density through a screening effect, thus, the output of the NG is sensitive to the gas concentration. Based on such a mechanism, we first studied the responses of an unpackaged NG to oxygen, H2S and water vapor, and demonstrated its sensitivity to H2S to a level as low as 100 ppm. Therefore, the piezoelectric signal generated by a ZnO NWs NG can act not only as a power source, but also as a response signal to the gas, demonstrating a possible approach as a self-powered active gas sensor. PMID:23633477

  15. Quasi-three-level room-temperature Nd:YAG ring laser with high single-frequency output power at 946 nm

    SciTech Connect

    Freitag, I.; Henking, R.; Tuennermann, A.; Welling, H.

    1995-12-01

    Efficient room-temperature operation of a diode-pumped Nd:YAG laser is demonstrated for the quasi-three-level transition at 946 nm. Continuous-wave output powers of more than 800 mW cw in single-frequency operation are generated by application of a composite-cavity nonplanar ring laser. High amplitude and frequency stability of the emitted radiation is observed. {copyright} {ital 1995 Optical Society of America.}

  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. 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

  18. Influence of defects in the output power of c- and a-axis growth Nd:YVO4 single laser crystals

    NASA Astrophysics Data System (ADS)

    Shawley, Charles R.; Wang, Cai-Lin; Lynn, Kelvin G.

    2006-06-01

    The differences in the output powers of a- and c-axis growth neodymium-doped yttrium orthovanadate (Nd:YVO4) crystals grown by the Czochralski method were investigated. It was found that the differences in the output powers are due to crystal defects, such as veils and grain boundaries, which lead to changes in the thermal and optical properties of Nd:YVO4 and reduce the quality of the laser beam. To relieve internal stresses introduced by the crystal growth process, boules form grain boundaries and other thermodynamically favorable defects in the boule. Because c-axis grown Nd:YVO4 crystals do not contain a slip system, no grain boundaries or ghost veils can form. As a result, c-axis grown boules are highly vulnerable to thermal and stress fractures and require careful growth parameter selection to overcome these defects. However, a-axis grown crystal contain a slip system and can form thermodynamically stable defects including grain boundaries, scatter centers, and ghost veils. In this paper, data are presented showing that properly grown c-axis growth crystal, having no grain boundaries or veils, is more suited for high output power applications than a-axis grown one.

  19. Efficient light output power for InGaP/GaAs heterojunction bipolar transistors incorporated with InGaAs quantum wells

    NASA Astrophysics Data System (ADS)

    Huang, Tzu-Hsuan; Wu, Meng-Chyi

    2016-07-01

    In this work, the current gain and optical frequency response of the heterojunction bipolar transistor (HBT) and heterojunction bipolar light-emitting transistor (HBLET) are investigated. Compared to the conventional HBT, two-pair quantum wells are embedded in the base region of the HBLET. The current gain of HBLET increases with temperature, which shows dissimilar electrical properties to the HBT. Although the current gain of HBLET is much smaller than that of HBT, the decrement of current gain is converted to enhance the light output power. The light output power of HBLET can reach 0.96 mW at 90 mA. The HBLET exhibits the 3-dB bandwidths (f3dB) of 554 and 559 MHz at 30 and 50 mA, respectively. It is found that the 3-dB frequency is proportional to the square root of base current density, while the minority carrier lifetime is inversely proportional to the square root of base current density. Therefore, our results suggest that HBLET with the high light output power shows a great potential in the short range optical data communications.

  20. Linear output nitinol engine

    SciTech Connect

    Banks, R.M.

    1986-01-14

    This patent describes a linear output nitinol engine consisting of a number of integrated communicating parts. The engine has an external support framework which is described in detail. The patent further describes a wire transport mechanism, a pair of linkage levers with a loom secured to them, a number of nitinol wires strung between the looms, and a power takeoff block secured to the linkage levers. A pulley positioned in a flip-flop supporting bracket and a power takeoff modality including a tension member connected to a power output cable in order to provide linear power output transmission is described. A method for biasing the timing and the mechanism for timing the synchronization of the throw over arms and the flip-flop of the pulley are also described.

  1. 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.

  2. 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.

  3. Generation of 25 ps pulses by self induced mode locking of a single broad area diode laser with 300 mW average output power

    NASA Astrophysics Data System (ADS)

    Skoczowsky, D.; Heuer, A.; Jechow, A.; Menzel, R.

    2007-11-01

    Detailed investigations of the spatiotemporal and spectral emission properties of a high power diode laser are presented. The AR coated laser diode with design wavelength of 940 nm is driven in an external resonator. The laser generates up to 340 mW average output power in a train of picosecond pulses with durations of 25 ps and repetition rates of 2.6 GHz. The mechanism of mode locking is discussed as self pulsation because of the strong correlation between round trip time and repetition rate. The double-sided exponential pulses suggest saturable absorber action.

  4. 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. PMID:26367971

  5. Evaluation of a novel solid-state method for determining the acoustic power generated by physiotherapy ultrasound transducers.

    PubMed

    Zeqiri, Bajram; Barrie, Jill

    2008-09-01

    A new secondary method of determining ultrasound power is presented based on the pyroelectricity of a thin membrane of the piezoelectric polymer, polyvinylidene fluoride (PVDF). In operation, the membrane is backed by a polyurethane-based rubber material that is extremely attenuating to ultrasound, resulting in the majority of the acoustic power applied to the PVDF being absorbed within a short distance of the membrane-backing interface. The resulting rapid heating leads to a pyroelectric voltage being generated across the electrodes of the sensor that, under appropriate conditions, is related to the rate of change of temperature with respect to time. For times immediately after changes in transducer excitation (switching either ON or OFF), the change in the pyroelectric voltage is proportional to the delivered ultrasound power level. This paper describes a systematic evaluation of the measurement concept applied at physiotherapy frequencies and power levels, investigating key aspects such as repeatability, linearity and sensitivity. The research demonstrates the way that heating of the backing material affects the sensor performance, but outlines the potential of the method as a reproducible, rapid, solid-state method of determining power, requiring calibration using a known ultrasound power source. PMID:18440695

  6. Investigation of Laser Output Power Saturation in the He-Cu+ IR Hollow Cathode Discharge Laser by Experiments and Numerical Modeling

    NASA Astrophysics Data System (ADS)

    Bogaerts, A.; Gijbels, R.; Grozeva, M.; Sabotinov, N.

    Saturation in the laser output power at high electrical currents is experimentally observed for a He-Cu+ IR HCD laser. To investigate which mechanisms might be responsible for the laser power saturation, a modeling network is developed for a helium-argon-copper hollow cathode discharge (HCD), and is applied to the conditions for which saturation is observed. Typical calculation results, such as the potential distribution, the densities of the various plasma species, the sputtering flux and the ionization degree of copper, are presented as a function of electrical current. The calculated densities of electrons, Cu atoms and Cu+ ions, as well as the sputtering flux and the ionization degree of copper, increase with electrical current, whereas the He+ ion density is found to be constant. The laser output power itself cannot yet be predicted by the model, due to insufficient knowledge about the relevant populating and depopulating processes of the upper and lower laser levels and the corresponding cross sections. However, the model can make predictions on the production of the upper laser level (by asymmetric charge transfer between Cu atoms and He+ ions). The latter is found to increase less rapidly with current at higher values of the electrical current, which is attributed to the rise in gas temperature at higher electrical currents, and it suggests a certain degree of saturation in the laser output power. However, full saturation in the production rate of the upper laser level was not obtained with our calculations. Hence, the observed laser power saturation at high currents is probably also due to (i) either increasing depopulation of the upper laser level, or (ii) increasing population of the lower laser level, resulting in a drop in the population inversion.

  7. 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.

  8. 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

  9. 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.

  10. 200W output power at 10ps from a scalable Z-slab Nd:YAG laser

    NASA Astrophysics Data System (ADS)

    Kwon, Young Key; Chard, Simon P.; Hay, Nick; Rodin, Aleksej M.; Bass, Michael; Chen, Ying; Shu, Hong; Webster, Scott

    2014-02-01

    We demonstrate power scaling of an Nd:YAG picosecond master oscillator power amplifier system to over 200 W. The `z-slab' amplifier design is a power scalable, edge-pumped zigzag slab amplifier architecture, and it is demonstrated here in two alternative multi-stage implementations at 1064 nm using a picosecond seed laser. In a simple design, an average power of 225 W was generated with up to 450 μJ pulse energy at 11 ps pulse duration. In a compact multi-pass design, 150 W was generated with M2 < 1.75.

  11. Free electron laser with small period wiggler and sheet electron beam: A study of the feasibility of operation at 300 GHz with 1 MW CW output power

    SciTech Connect

    Booske, J.H.; Granatstein, V.L.; Antonsen, T.M. Jr.; Destler, W.W.; Finn, J.; Latham, P.E.; Levush, B.; Mayergoyz, I.D.; Radack, D.; Rodgers, J.

    1988-01-01

    The use of a small period wiggler (/ell//sub ..omega../ < 1 cm) together with a sheet electron beam has been proposed as a low cost source of power for electron cyclotron resonance heating (ECRH) in magnetic fusion plasmas. Other potential applications include space-based radar systems. We have experimentally demonstrated stable propagation of a sheet beam (18 A. 1 mm /times/ 20 mm) through a ten-period wiggler electromagnet with peak field of 1.2 kG. Calculation of microwave wall heating and pressurized water cooling have also been carried out, and indicate the feasibility of operating a near-millimeter, sheet beam FEL with an output power of 1 MW CW (corresponding to power density into the walls of 2 kW/cm/sup 2/). Based on these encouraging results, a proof-of-principle experiment is being assembled, and is aimed at demonstrating FEL operating at 120 GHz with 300 kW output power in 1 ..mu..s pulses: electron energy would be 410 keV. Preliminary design of a 300 GHz 1 MW FEL with an untapered wiggler is also presented. 10 refs., 5 figs., 3 tabs.

  12. Acoustic neuroma

    MedlinePlus

    Vestibular schwannoma; Tumor - acoustic; Cerebellopontine angle tumor; Angle tumor ... Acoustic neuromas have been linked with the genetic disorder neurofibromatosis type 2 (NF2). Acoustic neuromas are uncommon.

  13. 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.

  14. All-solid-state dual end pumped Nd:YAG/LBO yellow green laser with 10.8 W output power at 561 nm

    NASA Astrophysics Data System (ADS)

    Zhu, P. F.; Zhang, C. M.; Song, P.; Bai, L.; Yao, Y.

    2015-04-01

    It is reported that the efficient and compact yellow green laser at 561 nm generated by intracavity frequency doubling of a continuous wave (CW) laser operation of a diode pumped Nd:YAG laser on the 4 F 3/2 → 4 F 13/2 transition operated at 1123 nm. An LBO crystal, cut for critical type I phase matching at room temperature is used for second harmonic generation of the laser. With dual end pump configurations at total incident pump power of 40 W, as high as 10.8 W of CW output power at 561 nm is achieved with 20 mm long LBO. The optical-to-optical conversion efficiency is up to 27%, and the power stability in 8 h is better than 2.56%.

  15. All-solid-state dual end pumped YVO4:Nd/LBO blue laser with 21.8 W output power at 457 nm

    NASA Astrophysics Data System (ADS)

    Ling, Zhao; Yi, Yao; Yang, Zhao; Quan, Zheng

    2014-03-01

    It is reported the efficient compact deep-blue laser at 457 nm generation by intracavity frequency doubling of a continuous wave (CW) laser operation of a diode-pumped YVO4:Nd laser on the 4 F 3/2 → 4 I 9/2 transition at 914 nm. An LBO crystal, cut for critical type I phase matching at room temperature is used for second harmonic generation (SHG) of the laser. With dual end pump configurations at total incident pump power of 60 W, as high as 21.8 W of CW output power at 457 nm is achieved with 20-mm-long LBO. The optical-to-optical conversion efficiency is up to 36.3%, and the power stability in 8 h is better than 2.36%.

  16. DBR tapered diode laser at 1030 nm with nearly diffraction-limited narrowband emission and 12.7 W of optical output power

    NASA Astrophysics Data System (ADS)

    Müller, André; Fricke, Jörg; Bugge, Frank; Brox, Olaf; Erbert, Götz; Sumpf, Bernd

    2016-03-01

    Nearly diffraction-limited emission from a distributed Bragg reflector (DBR) tapered diode laser is presented. Intrinsic wavelength stabilization is achieved with a 3rd order DBR grating manufactured by electron beam lithography. At a heatsink temperature of 15°C an optical output power of 12.7 W with an electro-optical efficiency > 40% is obtained. The corresponding emission wavelength is 1030.57 nm and spectral bandwidths of 0.02 nm are measured over the whole power range. At 10.5 W of optical power 8.1 W are contained in the central lobe. The measured beam propagation ratio and brightness are 1.1 (1/e2) and 700 MWcm-2 sr-1, respectively. With these parameters, the laser is suitable for applications such as non-linear frequency conversion.

  17. 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.

  18. 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.

  19. 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.

  20. All-solid-state doubly resonant intracavity frequency sum mixing orange yellow laser with 3.2 W output power at 593.5 nm

    NASA Astrophysics Data System (ADS)

    Zhu, P. F.; Li, B.; Liu, W. Q.; Liu, T. H.; Fang, C. X.; Zhano, Y.; Yao, Y.; Zheng, Q.

    2013-01-01

    A compact and efficient 593.5 nm orange-yellow laser is realized using doubly resonant intracavity sum frequency mixing. Two Nd: YVO4 crystals are employed as the gain crystals. In two sub-cavities, 1064 nm radiation from one Nd: YVO4 and 1342 nm radiation from the other Nd: YVO4 are mixed to generate 593.5 nm orange-yellow laser. In the overlapping of the two cavities, sum frequency mixing is achieved in a type I critical phase matching (CPM) LBO crystal. An output power of 3.2 W at the wavelength of 593.5 nm is obtained with total incident pump power of 38 W. The optical to optical conversion efficiency is up to 8.4% and the stability of the output power is better than 2.48% in 8 h. To the best knowledge, this it the highest watt-level laser at 593.5 nm generated by diode end pump all-solid-state technology.

  1. Output power and intracavity intensity profiles of a quasi-continuous end-pumped Nd:YVO4 self-Raman mini laser

    NASA Astrophysics Data System (ADS)

    Kananovich, A. A.; Voitikov, S. V.; Demidovich, A. A.; Danailov, M. B.; Orlovich, V. A.

    2012-01-01

    The paper presents experimental investigation and modeling of an end-pumped quasi-continuous-wave YVO4/Nd:YVO4 mini self-Raman laser. The dependence of the Stokes output power on the pump power in the range from 3 to 17.5 W has been measured. As much as 1.76 W of an average Stokes power, corresponding to a total optical-to-optical conversion efficiency of about 10%, has been obtained. The transverse profiles of the laser (at the fundamental wavelength) and the Stokes beam intensity have been recorded at the output mirror and in the vicinity of the boundary between the pure and Nd-doped parts of the Raman crystal. These distributions have been approximated by the sum of Gaussian and super-Gaussian distributions with corresponding weights. We propose a model of such lasers that takes into account the features of intracavity self-frequency Raman conversion in lasers with highly inhomogeneous non-Gaussian spatial distributions of the pump, laser, and Stokes beam intensity in the cavity. The results of modeling are in good agreement with the experimental data.

  2. A new sensor for detection of coolant leakage in nuclear power plants using off-axis integrated cavity output spectroscopy

    NASA Astrophysics Data System (ADS)

    Lee, Lim; Park, Hyunmin; Kim, Taek-Soo; Ko, Kwang-Hoon; Jeong, Do-Young

    2012-06-01

    A new sensor based on laser absorption spectroscopy was developed for the detection of coolant leakage which may happen in pressurized heavy water reactor (PHWR). Off-axis integrated output spectroscopy (OA-ICOS) technique was adopted for developing a simple and robust sensor with sufficient sensitivity. Leak events could be monitored by detecting a small change in semi-heavy water (HDO) concentration induced by the exchange reaction of leaked heavy water (D2O) with light water (H2O). From the results of feasibility tests, we have shown that the measured area of absorption features was linearly correlated with HDO concentration, and the minimum detectable change of HDO concentration with the developed sensor was evaluated as 3.2 ppm. This new sensor is expected to be a reliable and promising device for the detection of coolant leakage since it has some advantages on real-time monitoring and early detection for nuclear safety.

  3. 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.

  4. 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.

  5. The power output of local obscured and unobscured AGN: crossing the absorption barrier with Swift/BAT and IRAS

    NASA Astrophysics Data System (ADS)

    Vasudevan, R. V.; Fabian, A. C.; Gandhi, P.; Winter, L. M.; Mushotzky, R. F.

    2010-02-01

    The Swift/Burst Alert Telescope (BAT) 9-month catalogue of active galactic nuclei (AGN) provides an unbiased census of local supermassive black hole accretion, and probes to all but the highest levels of absorption in AGN. We explore a method for characterizing the bolometric output of both obscured and unobscured AGN by combining the hard X-ray data from the Swift/BAT instrument (14-195keV) with the reprocessed infrared (IR) emission as seen with the Infrared Astronomical Satellite (IRAS) all-sky surveys. This approach bypasses the complex modifications to the spectral energy distribution introduced by absorption in the optical, UV and 0.1-10 keV regimes and provides a long-term, average picture of the bolometric output of these sources. We broadly follow the approach of Pozzi et al. for calculating the bolometric luminosities by adding nuclear IR and hard X-ray luminosities, and consider different approaches for removing non-nuclear contamination in the large-aperture IRAS fluxes. Using mass estimates from the black hole mass-host galaxy bulge luminosity relation, we present the Eddington ratios λEdd and 2-10 keV bolometric corrections for a subsample of 63 AGN (35 obscured and 28 unobscured) from the Swift/BAT catalogue, and confirm previous indications of a low Eddington ratio distribution for both samples. Importantly, we find a tendency for low bolometric corrections (typically 10-30) for the obscured AGN in the sample (with a possible rise from ~15 for λEdd < 0.03 to ~32 above this), providing a hitherto unseen window on to accretion processes in this class of AGN. This finding is of key importance in calculating the expected local black hole mass density from the X-ray background since it is composed of emission from a significant population of such obscured AGN. Analogous studies with high-resolution IR data and a range of alternative models for the torus emission will form useful future extensions to this work.

  6. 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)

  7. Acoustic emission monitoring for inspection of seam-welded hot reheat piping in fossil power plants

    NASA Astrophysics Data System (ADS)

    Rodgers, John M.; Morgan, Bryan C.; Tilley, Richard M.

    1996-11-01

    Although failure of the seam weld on reheat steam piping has been an infrequent occurrence, such failure is still a major safety concern for fossil plant operations. EPRI has provided guidelines for a piping management program base don periodic inspection. More recently, EPRI has also sponsored research to develop inspection techniques to both improve the quality and reduce the cost of piping inspections. Foremost in this research has been the use of acoustic emission (AE) techniques to detect crack damage in seam welds. AE has the substantial cost advantages of both allowing inspection without full removal of the thermal insulation on the reheat piping and making short-re- inspection intervals practical. This paper reviews the EPRI guidelines for performing an AE inspection on seam-welded hot reheat piping.

  8. 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.

  9. 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.

  10. 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

  11. 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.

  12. 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.

  13. 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.

  14. Research of narrow pulse width, high repetition rate, high output power fiber lasers for deep space exploration

    NASA Astrophysics Data System (ADS)

    Tang, Yan-feng; Li, Hong-zuo; Wang, Yan; Hao, Zi-qiang; Xiao, Dong-Ya

    2013-08-01

    As human beings expand the research in unknown areas constantly, the deep space exploration has become a hot research topic all over the world. According to the long distance and large amount of information transmission characteristics of deep space exploration, the space laser communication is the preferred mode because it has the advantages of concentrated energy, good security, and large information capacity and interference immunity. In a variety of laser source, fibre-optical pulse laser has become an important communication source in deep space laser communication system because of its small size, light weight and large power. For fiber lasers, to solve the contradiction between the high repetition rate and the peak value power is an important scientific problem. General Q technology is difficult to obtain a shorter pulse widths, This paper presents a DFB semiconductor laser integrated with Electro-absorption modulator to realize the narrow pulse width, high repetition rate of the seed source, and then using a two-cascaded high gain fiber amplifier as amplification mean, to realize the fibre-optical pulse laser with pulse width 3ns, pulse frequency 200kHz and peak power 1kW. According to the space laser atmospheric transmission window, the wavelength selects for 1.06um. It is adopted that full fibre technology to make seed source and amplification, pumping source and amplification of free-space coupled into fiber-coupled way. It can overcome that fibre lasers are vulnerable to changes in external conditions such as vibration, temperature drift and other factors affect, improving long-term stability. The fiber lasers can be modulated by PPM mode, to realize high rate modulation, because of its peak power, high transmission rate, narrow pulse width, high frequency stability, all technical indexes meet the requirements of the exploration of deep space communication technology.

  15. High-power integrated stimulator output stages with floating discharge over a wide voltage range for nerve stimulation.

    PubMed

    Langlois, P J; Demosthenous, A; Pachnis, I; Donaldson, N

    2010-02-01

    Two integrated nerve stimulator circuits are described. Both generate passively charge-balanced biphasic stimulating pulses of 1 to 16 mA with 10-¿s to 1-ms widths from 6- to 24-V supplies for implanted book electrodes. In both circuits, the electrodes are floating during the passive discharge anywhere within the range of the power rails, which may be up to 24 V. The first circuit is used for stimulation only. It uses a floating depletion transistor to enable continuous discharge of the electrodes, except when stimulating, without using power. The second circuit also allows neural signals to be recorded from the same tripole. It uses a modified floating complementary metal-oxide semiconductor (CMOS) discharge switch capable of operating over a range beyond the gate-to-source voltage limits of its transistors. It remains off for long periods using no power while recording. A 0.6-¿m silicon-on-insulator CMOS technology has been used. The measured performance of the circuits has been verified using multiple tripoles in saline. PMID:23853308

  16. 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.

  17. Enhanced light output power in InGaN/GaN light-emitting diodes with a high reflective current blocking layer

    NASA Astrophysics Data System (ADS)

    Xiaojie, Zhang; Ruixia, Yang; Jinghui, Wang

    2012-07-01

    The light output power of an InGaN/GaN light-emitting diode is improved by using a SiO2/TiO2 distributed Bragg reflector (DBR) and an Al mirror as a hybrid reflective current blocking layer (CBL). Such a hybrid reflective CBL not only plays the role of the CBL by enhancing current spreading but also plays the role of a reflector by preventing photons near the p-electrode pad from being absorbed by a metal electrode. At a wavelength of 455 nm, a 1.5-pair of SiO2/TiO2 DBR and an Al mirror (i.e. 1.5-pair DBR+Al) deposited on a p-GaN layer showed a normal-incidence reflectivity as high as 97.8%. With 20 mA current injection, it was found that the output power was 25.26, 24.45, 23.58 and 22.45 mW for the LED with a 1.5-pair DBR+Al CBL, a 3-pair DBR CBL, SiO2 CBL and without a CBL, respectively.

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

    NASA Astrophysics Data System (ADS)

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

    2015-06-01

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

  19. 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

  20. On the relationship between acoustic energy density flux near the jet and far field acoustic intensity

    NASA Technical Reports Server (NTRS)

    Maestrello, L.

    1973-01-01

    The relationship between the distribution of the outflow of acoustic energy over the jet boundary and the far-field directivity and intensity distribution is established by measurement and analysis. The numerical and experimental procedures involved have been checked out by using a known source. The results indicate that the acoustic power output per unit length of the jet, in the region from which the sound emanates, peaks at approximately 9 diameters downstream. The acoustic emission for a jet Strouhal number of about 0.3 exceeds the emission for all other Strouhal numbers nearly everywhere along the measurement plane. However, the far-field peak intensity distribution obtained from the contribution of each station was found to depend on the spatial extent of the region where sound emanates from the jet, which, in turn, depends more on the far-field angle than on the Strouhal number. The implications of these results for sound suppression techniques are discussed.

  1. 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.

  2. 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.

  3. Synchronized photonic modulators driven by surface acoustic waves.

    PubMed

    Crespo-Poveda, A; Hey, R; Biermann, K; Tahraoui, A; Santos, P V; Gargallo, B; Muñoz, P; Cantarero, A; de Lima, M M

    2013-09-01

    Photonic modulators are one of the most important elements of integrated photonics. We have designed, fabricated, and characterized a tunable photonic modulator consisting of two 180°-dephased output waveguide channels, driven by a surface acoustic wave in the GHz frequency range built on (Al,Ga)As. Odd multiples of the fundamental driven frequency are enabled by adjusting the applied acoustic power. A good agreement between theory and experimental results is achieved. The device can be used as a building block for more complex integrated functionalities and can be implemented in several material platforms. PMID:24104040

  4. 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. PMID:26159759

  5. 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

  6. Relationship between vertical jump and maximal power output of legs and arms: effects of ethnicity and sport.

    PubMed

    Rouis, M; Attiogbé, E; Vandewalle, H; Jaafar, H; Noakes, T D; Driss, T

    2015-04-01

    The hypothesis that ethnicity and sport practice influence the relationship between maximal power in cycling (P(max)) and countermovement jump (CMJ) has been studied by relating CMJ and P(max) in two groups (volleyball players, VB, and physical education students, PES) including subjects with Caucasian (67 C) or West African (39 WA) origins. Maximal power of the arms (P(max) Arms) was also measured. A two-way analysis of variance (groups × ethnicity) showed significant effects of both factors upon CMJ, which was higher in WA and VB, P = 0.002 and P < 0.001, respectively. Within WA, CMJ was significantly higher in VB (0.732 ± 0.057 m) than in PES (0.661 ± 0.082 m), although there was no difference in P(max) (14.7 ± 1.7 vs 14.7 ± 1.9 W/kg). CMJ was significantly higher in WA (0.69 ± 0.08 vs 0.65 ± 0.09 m in C, P = 0.002) without significant interethnic difference in P(max) (14.7 ± 1.8 in WA, and 14.8 ± 1.9 W/kg in C). The CMJ-P(max) relationships were different in C and WA (P = 0.003). Therefore, CMJ predicted from P(max) would be underestimated in WA. The same difference was observed for the relationship between CMJ and P(max) Arms. These results were confirmed by the comparison with previous P(max) -CMJ relationship in the literature, collected in Caucasian and African subjects with the same protocols. PMID:25048561

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

    PubMed Central

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

    2005-01-01

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

  8. Microwave Transmitter With Multimode Output Section

    NASA Technical Reports Server (NTRS)

    Hoppe, Daniel J.; Bhanji, Alaudin M.; Cormier, Reginald A.

    1988-01-01

    Output-waveguide structure transports 400 kW of continuous-wave signal power at 34.5 GHz. Transmitter generates 400 kW of continuous-wave (CW) signal power. Main feature of conceptual design of this microwave transmitter is output section. Output waveguide structure includes mode converter, directional coupler, polarization monitor, and corrugated overmoded output section. Output directional pattern suitable for antenna illumination without flared feedhorn.

  9. 600 mW optical output power at 488 nm by use of a high-power hybrid laser diode system and a periodically poled MgO:LiNbO3 bulk crystal.

    PubMed

    Maiwald, Martin; Schwertfeger, Sven; Güther, Reiner; Sumpf, Bernd; Paschke, Katrin; Dzionk, Christian; Erbert, Götz; Tränkle, Günther

    2006-03-15

    600 mW second-harmonic blue light at 488 nm has been generated by use of a master-oscillator power amplifier diode laser system as a pump source with a maximum optical output power of 4 W in continuous-wave operation. For frequency doubling, a periodically poled MgO:LiNbO3 bulk crystal was used in a single-pass configuration. A conversion efficiency of 15% and an overall wall-plug efficiency of 4% were achieved. PMID:16544629

  10. Barbell kinematics should not be used to estimate power output applied to the Barbell-and-body system center of mass during lower-body resistance exercise.

    PubMed

    Lake, Jason P; Lauder, Mike A; Smith, Neal A

    2012-05-01

    The aim of this study was to compare measures of power output applied to the center of mass of the barbell and body system (CM) obtained by multiplying ground reaction force (GRF) by (a) the velocity of the barbell; (b) the velocity of the CM derived from three-dimensional (3D) whole-body motion analysis, and (c) the velocity of the CM derived from GRF during lower-body resistance exercise. Ten resistance-trained men performed 3 maximal-effort single back squats with 60% 1 repetition maximum while GRF and whole-body motion were captured using synchronized Kistler force platforms and a Vicon Motus motion analysis system. Repeated measures analysis of variance of time-normalized kinematic and kinetic data obtained using the different methods showed that the barbell was displaced 13.4% (p < 0.05) more than the CM, the velocity of the barbell was 16.1% (p < 0.05) greater than the velocity of the CM, and power applied to the CM obtained by multiplying GRF by the velocity of the barbell was 18.7% (p < 0.05) greater than power applied to the CM obtained by multiplying the force applied to the CM by its resultant velocity. Further, the velocity of the barbell was significantly greater than the velocity of the trunk, upper leg, lower leg, and foot (p < 0.05), indicating that a failure to consider the kinematics of body segments during lower-body resistance exercise can lead to a significant overestimation of power applied to the CM. Strength and conditioning coaches and investigators are urged to obtain measures of power from the force applied to and the velocity of either the barbell (using inverse dynamics) or CM (GRF or 3D motion analysis). Failure to apply these suggestions could result in continued overestimation of CM power, compromising methodological integrity. PMID:22516904

  11. 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.

  12. Effect of formoterol, a long-acting β2-adrenergic agonist, on muscle strength and power output, metabolism, and fatigue during maximal sprinting in men.

    PubMed

    Kalsen, Anders; Hostrup, Morten; Backer, Vibeke; Bangsbo, Jens

    2016-06-01

    The aim was to investigate the effect of the long-acting β2-adrenergic agonist formoterol on muscle strength and power output, muscle metabolism, and phosphorylation of CaMKII Thr(287) and FXYD1 during maximal sprinting. In a double-blind crossover study, 13 males [V̇o2 max: 45.0 ± 0.2 (means ± SE) ml·min(-1)·kg(-1)] performed a 30-s cycle ergometer sprint after inhalation of either 54 μg of formoterol (FOR) or placebo (PLA). Before and after the sprint, muscle biopsies were collected from vastus lateralis and maximal voluntary contraction (MVC), and contractile properties of quadriceps were measured. Oxygen uptake was measured during the sprint. During the sprint, peak power, mean power, and end power were 4.6 ± 0.8, 3.9 ± 1.1, and 9.5 ± 3.2% higher (P < 0.05) in FOR than in PLA, respectively. Net rates of glycogenolysis and glycolysis were 45.7 ± 21.0 and 28.5 ± 13.4% higher (P < 0.05) in FOR than in PLA, respectively, and the decrease in ATP content was lower (P < 0.05) in FOR than in PLA (3.7 ± 1.5 vs. 8.0 ± 1.6 mmol/kg dry weight). There was no difference in breakdown of phosphocreatine and oxygen uptake between treatments. Before and after the sprint, MVC and peak twitch force were higher (P < 0.05) in FOR than in PLA. No differences were observed in phosphorylation of CaMKII Thr(287) and FXYD1 between treatments before the sprint, whereas phosphorylation of CaMKII Thr(287) and FXYD1 was greater (P < 0.05) in FOR than in PLA after the sprint. In conclusion, formoterol-induced enhancement in power output during maximal sprinting is associated with increased rates of glycogenolysis and glycolysis that may counteract development of fatigue. PMID:27147617

  13. From cycling between coupled reactions to the cross-bridge cycle: mechanical power output as an integral part of energy metabolism.

    PubMed

    Diederichs, Frank

    2012-01-01

    ATP delivery and its usage are achieved by cycling of respective intermediates through interconnected coupled reactions. At steady state, cycling between coupled reactions always occurs at zero resistance of the whole cycle without dissipation of free energy. The cross-bridge cycle can also be described by a system of coupled reactions: one energising reaction, which energises myosin heads by coupled ATP splitting, and one de-energising reaction, which transduces free energy from myosin heads to coupled actin movement. The whole cycle of myosin heads via cross-bridge formation and dissociation proceeds at zero resistance. Dissipation of free energy from coupled reactions occurs whenever the input potential overcomes the counteracting output potential. In addition, dissipation is produced by uncoupling. This is brought about by a load dependent shortening of the cross-bridge stroke to zero, which allows isometric force generation without mechanical power output. The occurrence of maximal efficiency is caused by uncoupling. Under coupled conditions, Hill's equation (velocity as a function of load) is fulfilled. In addition, force and shortening velocity both depend on [Ca2+]. Muscular fatigue is triggered when ATP consumption overcomes ATP delivery. As a result, the substrate of the cycle, [MgATP2-], is reduced. This leads to a switch off of cycling and ATP consumption, so that a recovery of [ATP] is possible. In this way a potentially harmful, persistent low energy state of the cell can be avoided. PMID:24957757

  14. Adaptations in upper-body maximal strength and power output resulting from long-term resistance training in experienced strength-power athletes.

    PubMed

    Baker, Daniel G; Newton, Robert U

    2006-08-01

    The purpose of this investigation was to observe changes in maximal upper-body strength and power and shifts in the load-power curve across a multiyear period in experienced resistance trainers. Twelve professional rugby league players who regularly performed combined maximal strength and power training were observed across a 4-year period with test data reported every 2 years (years 1998, 2000, and 2002). Upper-body strength was assessed by the 1 repetition maximum bench press and maximum power during bench press throws (BT Pmax) with various barbell resistances of 40-80 kg. During the initial testing, players also were identified as elite (n = 6) or subelite (n = 6), depending upon whether they participated in the elite first-division national league or second-division league. This subgrouping allowed for a comparison of the scope of changes dependent upon initial strength and training experience. The subelite group was significantly younger, less strong, and less powerful than the elite group, but no other difference existed in height or body mass in 1998. Across the 4-year period, significant increases in strength occurred for the group as a whole and larger increases were observed for the subelite than the elite group, verifying the limited scope that exists for strength gain in more experienced, elite resistance-trained athletes. A similar trend occurred for changes in BT Pmax. This long-term observation confirms that the rate of progress in strength and power development diminishes with increased strength levels and resistance training experience. Furthermore, it also indicates that strength and power can still be increased despite a high volume of concurrent resistance and endurance training. PMID:16937966

  15. Design Modifications for Increasing the BOM and EOM Power Output and Reducing the Size and Mass of RTG for the Pluto Mission

    SciTech Connect

    Schock, Alfred; Or, Chuen T; Kumar, Vasanth

    1994-06-01

    A companion paper analyzed the effect on source modules for three specific fuel options, and compared the predicted power output with JPL's latest goals for the Pluto Fast Flyby (PFF) mission. The results showed that a 5-module RTG cannot fully meet JPL's goals with any of the available fuels; and that a 6-module RTG more than meets those goals with Russian fuel, almost meets them with U.S. (Cassini-type) fuel, but still falls far short of meeting them with the depleted fuel from the aged (1982) Galileo spare RTG. The inadequacy of the aged fuel was disappointing,because heat source modules made from it already exist, and their use in PFF could result in substantial cost savings. The present paper describes additional analyses which showed that a six-module RTG with the aged fuel can meet JPL's stipulated power margin with a relatively simple design modification, that a second design modification makes it possible to recover all of the mass and size penalty for going from five to six heat source modules, and that a third modification could raise the EOM power margin to 16%. There are four copies in the file. Cross Reference ESD Files FSC-ESD-217-94-531 (CID #8572)

  16. Design Modifications for Increasing the BOm and EOM Power Output and Reducing the Size and Mass of RTG for the Pluto Mission

    SciTech Connect

    Schock, Alfred; Or, Chuen T; Kumar, Vasanth

    1994-08-01

    Paper presented at the 29th IECEC in Monterey, CA in August 1994. A companion paper analyzed the effect on source modules for three specific fuel options, and compared the predicted power output with JPL's latest goals for the Pluto Fast Flyby (PFF) mission. The results showed that a 5-module RTG cannot fully meet JPL's goals with any of the available fuels; and that a 6-module RTG more than meets those goals with Russian fuel, almost meets them with U.S. (Cassini-type) fuel, but still falls far short of meeting them with the depleted fuel from the aged (1982) Galileo spare RTG. The inadequacy of the aged fuel was disappointing,because heat source modules made from it already exist, and their use in PFF could result in substantial cost savings. The present paper describes additional analyses which showed that a six-module RTG with the aged fuel can meet JPL's stipulated power margin with a relatively simple design modification, that a second design modification makes it possible to recover all of the mass and size penalty for going from five to six heat source modules, and that a third modification could raise the EOM power margin to 16%.

  17. Enhanced light output power of InGaN-based amber LEDs by strain-compensating AlN/AlGaN barriers

    NASA Astrophysics Data System (ADS)

    Iida, Daisuke; Lu, Shen; Hirahara, Sota; Niwa, Kazumasa; Kamiyama, Satoshi; Ohkawa, Kazuhiro

    2016-08-01

    We investigated the effect of a combined AlN/Al0.03Ga0.97N barrier on InGaN-based amber light-emitting diodes (LEDs) grown by metalorganic vapor-phase epitaxy. InGaN-based multiple quantum wells with a combined AlN/Al0.03Ga0.97N barrier showed intense photoluminescence with a narrow full-width at half-maximum. The amber LEDs with a combined AlN/Al0.03Ga0.97N barrier achieved a light output power enhanced approximately 2.5-fold at 20 mA compared to that of the LED with a combined AlN/GaN barrier, owing to the reduction of defects in InGaN active layers. Thus, the efficiency of high-In-content InGaN-based LEDs can be improved in the spectrum range of amber.

  18. Enhancement of Light Output Power and Modification of Beam Profile in InGaN/GaN Light Emitting Diodes with Micro Polygon Column Shaped Transparent

    NASA Astrophysics Data System (ADS)

    Lee, Mi So; Kim, Hyung Gu; Hye Kang, Ji; Ryu, Jae Hyoung; Kim, Hyun Kyu; Kim, Hee Yun; Uthirakumar, Periyayya; Hong, Chang-Hee

    2010-11-01

    We report on the fabrication of GaN-based light-emitting diodes (LEDs) with micro-polygon columns (MPC) obtained by selective area growth (SAG) using the technique of metal organic chemical vapor deposition (MOCVD). The SAG makes it possible to control the density, size and position of the micro polygon columns. The facet structure consists of a polygon column covered with {1101} facets. Columns with rough occur on the (0001) surface. The light output power of the MPC-LED was 53% higher than conventional LED. In addition, the light extraction efficiency of InGaN/GaN LEDs is significantly improved owing to the photon path length is shorter. It is possible to modify the beam profile via shaped transparent layer. Thus, this structure can provide photons with multiple chances of escaping from the LEDs surfaces.

  19. GaSb-based 2.X μm quantum-well diode lasers with low beam divergence and high output power

    NASA Astrophysics Data System (ADS)

    Rattunde, M.; Schmitz, J.; Kaufel, G.; Kelemen, M.; Weber, J.; Wagner, J.

    2006-02-01

    We report on GaSb-based 2.Xμm diode lasers with an improved waveguide design, leading to a reduced beam divergence in the fast axis of 44° full width at half maximum (FWHM), compared to 67° FWHM of a conventional broadened waveguide design. 2.3μm ridge-waveguide lasers with the improved epitaxial design showed, besides the narrow beam profile in the fast axis, an excellent slow axis beam quality [M2<1.1 up to 70mW, continuous wave (cw)]. 2.0μm broad-area lasers with the improved waveguide too, exhibit a maximum cw-output power of 1.96W.

  20. Modification of nitrogen Townsend ionization coefficient in a N2 laser with a weak corona preionization and high gas pressure using laser output power measurements

    NASA Astrophysics Data System (ADS)

    Sarikhani, S.; Hariri, A.

    2013-05-01

    Based on the reported experimental measurements on the output power in a transversely excited nitrogen laser with a weak corona preionization and rate equations, a simulation study was made to describe the laser output power behavior. For the study, we first made a literature survey for the appropriate E/p functional dependences of nitrogen molecules on drift velocity vd, and the Townsend ionization coefficient α, to be applied for the laser operational characteristics of high gas pressures up to 1 atmosphere, and 20 < E/p < 1000 V cm-1 Torr-1. For the study when the corona UV preionization is applied, it was realized that it is necessary to modify the Townsend ionization coefficient to include the effect of the preionization for the laser system. This realization revealed that the Townsend coefficient upon utilizing the corona effect, (α/p)corona, can be viewed as a perturbation to be added to the (α/p)main due to the main gas discharge, where the total (α/p)t = (α/p)main + (α/p)corona was used for the calculation. We also introduced a single α/p relation with A* and B* coefficients to explain the gas discharge due to both the main and corona discharges. The results of the two approaches are introduced and have been compared with each other. The present study indicates that laser optical measurements, by themselves, constitute a reliable approach for understanding the physical quantities that are involved during plasma formation in a gas discharge. Details of the approach will be presented in this paper.