Phase coded, micro-power impulse radar motion sensor

DOEpatents

McEwan, Thomas E.

1996-01-01

A motion sensing, micro-power impulse radar MIR impresses on the transmitted signal, or the received pulse timing signal, one or more frequencies lower than the pulse repetition frequency, that become intermediate frequencies in a "IF homodyne" receiver. Thus, many advantages of classical RF receivers can be thereby be realized with ultra-wide band radar. The sensor includes a transmitter which transmits a sequence of electromagnetic pulses in response to a transmit timing signal at a nominal pulse repetition frequency. A receiver samples echoes of the sequence of electromagnetic pulses from objects within the field with controlled timing, in response to a receive timing signal, and generates a sample signal in response to the samples. A timing circuit supplies the transmit timing signal to the transmitter and supplies the receive timing signal to the receiver. The relative timing of the transmit timing signal and the receive timing signal is modulated between a first relative delay and a second relative delay at an intermediate frequency, causing the receiver to sample the echoes such that the time between transmissions of pulses in the sequence and samples by the receiver is modulated at the intermediate frequency. Modulation may be executed by modulating the pulse repetition frequency which drives the transmitter, by modulating the delay circuitry which controls the relative timing of the sample strobe, or by modulating amplitude of the transmitted pulses. The electromagnetic pulses will have a nominal center frequency related to pulse width, and the first relative delay and the second relative delay between which the timing signals are modulated, differ by less than the nominal pulse width, and preferably by about one-quarter wavelength at the nominal center frequency of the transmitted pulses.

Phase coded, micro-power impulse radar motion sensor

DOEpatents

McEwan, T.E.

1996-05-21

A motion sensing, micro-power impulse radar MIR impresses on the transmitted signal, or the received pulse timing signal, one or more frequencies lower than the pulse repetition frequency, that become intermediate frequencies in a ``IF homodyne`` receiver. Thus, many advantages of classical RF receivers can be thereby be realized with ultra-wide band radar. The sensor includes a transmitter which transmits a sequence of electromagnetic pulses in response to a transmit timing signal at a nominal pulse repetition frequency. A receiver samples echoes of the sequence of electromagnetic pulses from objects within the field with controlled timing, in response to a receive timing signal, and generates a sample signal in response to the samples. A timing circuit supplies the transmit timing signal to the transmitter and supplies the receive timing signal to the receiver. The relative timing of the transmit timing signal and the receive timing signal is modulated between a first relative delay and a second relative delay at an intermediate frequency, causing the receiver to sample the echoes such that the time between transmissions of pulses in the sequence and samples by the receiver is modulated at the intermediate frequency. Modulation may be executed by modulating the pulse repetition frequency which drives the transmitter, by modulating the delay circuitry which controls the relative timing of the sample strobe, or by modulating amplitude of the transmitted pulses. The electromagnetic pulses will have a nominal center frequency related to pulse width, and the first relative delay and the second relative delay between which the timing signals are modulated, differ by less than the nominal pulse width, and preferably by about one-quarter wavelength at the nominal center frequency of the transmitted pulses. 5 figs.

Phonation threshold pressure predictions using viscoelastic properties up to 1,400 Hz of injectables intended for Reinke's space.

PubMed

Klemuk, Sarah A; Lu, Xiaoying; Hoffman, Henry T; Titze, Ingo R

2010-05-01

Viscoelastic properties of numerous vocal fold injectables have been reported but not at speaking frequencies. For materials intended for Reinke's space, ramifications of property values are of great concern because of their impact on ease of voice onset. Our objectives were: 1) to measure viscoelastic properties of a new nonresorbing carbomer and well-known vocal fold injectables at vocalization frequencies using established and new instrumentation, and 2) to predict phonation threshold pressures using a computer model with intended placement in Reinke's space. Rheology and phonation threshold pressure calculations. Injectables were evaluated with a traditional rotational rheometer and a new piezo-rotary vibrator. Using these data at vocalization frequencies, phonation threshold pressures (PTP) were calculated for each biomaterial, assuming a low dimensional model with supraglottic coupling and adjusted vocal fold length and thickness at each frequency. Results were normalized to a nominal PTP value. Viscoelastic data were acquired at vocalization frequencies as high as 363 to 1,400 Hz for six new carbomer hydrogels, Hylan B, and Extracel intended for vocal fold Reinke's space injection and for Cymetra (lateral injection). Reliability was confirmed with good data overlap when measuring with either rheometer. PTP predictions ranged from 0.001 to 16 times the nominal PTP value of 0.283 kPa. Accurate viscoelastic measurements of vocal fold injectables are now possible at physiologic frequencies. Hylan B, Extracel, and the new carbomer hydrogels should generate easy vocal onset and sustainable vocalization based on their rheologic properties if injected into Reinke's space. Applications may vary depending on desired longevity of implant. Laryngoscope, 2010.

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

NASA Technical Reports Server (NTRS)

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

2005-01-01

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

An Analysis of the High Frequency Vibrations in Early Thematic Mapper Scenes

NASA Technical Reports Server (NTRS)

Kogut, J.; Larduinat, E.

1984-01-01

The potential effects of high frequency vibrations on the final Thematic Mapper (TM) image are evaluated for 26 scenes. The angular displacements of the TM detectors from their nominal pointing directions as measured by the TM Angular Displacement Sensor (ADS) and the spacecraft Dry Rotor Inertial Reference Unit (DRIRU) give data on the along scan and cross scan high frequency vibrations present in each scan of a scene. These measurements are to find the maximum overlap and underlap between successive scans, and to analyze the spectrum of the high frequency vibrations acting on the detectors. The Fourier spectrum of the along scan and cross scan vibrations for each scene also evaluated. The spectra of the scenes examined indicate that the high frequency vibrations arise primarily from the motion of the TM and MSS mirrors, and that their amplitudes are well within expected ranges.

A MEMS Interface IC With Low-Power and Wide-Range Frequency-to-Voltage Converter for Biomedical Applications.

PubMed

Arefin, Md Shamsul; Redouté, Jean-Michel; Yuce, Mehmet Rasit

2016-04-01

This paper presents an interface circuit for capacitive and inductive MEMS biosensors using an oscillator and a charge pump based frequency-to-voltage converter. Frequency modulation using a differential crossed coupled oscillator is adopted to sense capacitive and inductive changes. The frequency-to-voltage converter is designed with a negative feedback system and external controlling parameters to adjust the sensitivity, dynamic range, and nominal point for the measurement. The sensitivity of the frequency-to-voltage converter is from 13.28 to 35.96 mV/MHz depending on external voltage and charging current. The sensitivity ranges of the capacitive and inductive interface circuit are 17.08 to 54.4 mV/pF and 32.11 to 82.88 mV/mH, respectively. A capacitive MEMS based pH sensor is also connected with the interface circuit to measure the high acidic gastric acid throughout the digestive tract. The sensitivity for pH from 1 to 3 is 191.4 mV/pH with 550 μV(pp) noise. The readout circuit is designed and fabricated using the UMC 0.18 μm CMOS technology. It occupies an area of 0.18 mm (2) and consumes 11.8 mW.

Evaluation of a scale-model experiment to investigate long-range acoustic propagation

NASA Technical Reports Server (NTRS)

Parrott, Tony L.; Mcaninch, Gerry L.; Carlberg, Ingrid A.

1987-01-01

Tests were conducted to evaluate the feasibility of using a scale-model experiment situated in an anechoic facility to investigate long-range sound propagation over ground terrain. For a nominal scale factor of 100:1, attenuations along a linear array of six microphones colinear with a continuous-wave type of sound source were measured over a wavelength range from 10 to 160 for a nominal test frequency of 10 kHz. Most tests were made for a hard model surface (plywood), but limited tests were also made for a soft model surface (plywood with felt). For grazing-incidence propagation over the hard surface, measured and predicted attenuation trends were consistent for microphone locations out to between 40 and 80 wavelengths. Beyond 80 wavelengths, significant variability was observed that was caused by disturbances in the propagation medium. Also, there was evidence of extraneous propagation-path contributions to data irregularities at more remote microphones. Sensitivity studies for the hard-surface and microphone indicated a 2.5 dB change in the relative excess attenuation for a systematic error in source and microphone elevations on the order of 1 mm. For the soft-surface model, no comparable sensitivity was found.

Implications of Systematic Nominator Missingness for Peer Nomination Data

ERIC Educational Resources Information Center

Babcock, Ben; Marks, Peter E. L.; van den Berg, Yvonne H. M.; Cillessen, Antonius H. N.

2018-01-01

Missing data are a persistent problem in psychological research. Peer nomination data present a unique missing data problem, because a nominator's nonparticipation results in missing data for other individuals in the study. This study examined the range of effects of systematic nonparticipation on the correlations between peer nomination data when…

Calibration of a proton beam energy monitor.

PubMed

Moyers, M F; Coutrakon, G B; Ghebremedhin, A; Shahnazi, K; Koss, P; Sanders, E

2007-06-01

Delivery of therapeutic proton beams requires an absolute energy accuracy of +/-0.64 to 0.27 MeV for patch fields and a relative energy accuracy of +/-0.10 to 0.25 MeV for tailoring the depth dose distribution using the energy stacking technique. Achromatic switchyard tunes, which lead to better stability of the beam incident onto the patient, unfortunately limit the ability of switchyard magnet tesla meters to verify the correct beam energy within the tolerances listed above. A new monitor to measure the proton energy before each pulse is transported through the switchyard has been installed into a proton synchrotron. The purpose of this monitor is to correct and/or inhibit beam delivery when the measured beam energy is outside of the tolerances for treatment. The monitor calculates the beam energy using data from two frequency and eight beam position monitors that measure the revolution frequency of the proton bunches and the effective offset of the orbit from the nominal radius of the synchrotron. The new energy monitor has been calibrated by measuring the range of the beam through water and comparing with published range-energy tables for various energies. A relationship between depth dose curves and range-energy tables was first determined using Monte Carlo simulations of particle transport and energy deposition. To reduce the uncertainties associated with typical scanning water phantoms, a new technique was devised in which the beam energy was scanned while fixed thickness water tanks were sandwiched between two fixed parallel plate ionization chambers. Using a multitude of tank sizes, several energies were tested to determine the nominal accelerator orbit radius. After calibration, the energy reported by the control system matched the energy derived by range measurements to better than 0.72 MeV for all nine energies tested between 40 and 255 MeV with an average difference of -0.33 MeV. A study of different combinations of revolution frequency and radial offsets to test the envelope of algorithm accuracy demonstrated a relative accuracy of +/-0.11 MeV for small energy changes between 126 and 250 MeV. These new measurements may serve as a data set for benchmarking range-energy relationships.

Magnetosheath electrostatic turbulence

NASA Technical Reports Server (NTRS)

Rodriquez, P.

1977-01-01

The spectrum of electrostatic plasma waves in the terrestrial magnetosheath was studied using the plasma wave experiment on the IMP-6 satellite. Electrostatic plasma wave turbulence is almost continuously present throughout the magnetosheath with broadband (20 Hz- 70 kHz) r.m.s. field intensities typically 0.01 - 1.0 millivolts/m. Peak intensities of about 1.0 millivolts/m near the electron plasma frequency (30 - 60 kHz) were detected occasionally. The components usually identified in the spectrum of magnetosheath electrostatic turbulence include a high frequency ( or = 30 kHz) component peaking at the electron plasma frequency f sub pe, a low frequency component with a broad intensity maximum below the nominal ion plasma frequency f sub pi (approximately f sub pe/43), and a less well defined intermediate component in the range f sub pi f f sub pe. The intensity distribution of magnetosheath electrostatic turbulence clearly shows that the low frequency component is associated with the bow shock, suggesting that the ion heating begun at the shock continues into the downstream magnetosheath.

Large-angle slewing maneuvers for flexible spacecraft

NASA Technical Reports Server (NTRS)

Chun, Hon M.; Turner, James D.

1988-01-01

A new class of closed-form solutions for finite-time linear-quadratic optimal control problems is presented. The solutions involve Potter's solution for the differential matrix Riccati equation, which assumes the form of a steady-state plus transient term. Illustrative examples are presented which show that the new solutions are more computationally efficient than alternative solutions based on the state transition matrix. As an application of the closed-form solutions, the neighboring extremal path problem is presented for a spacecraft retargeting maneuver where a perturbed plant with off-nominal boundary conditions now follows a neighboring optimal trajectory. The perturbation feedback approach is further applied to three-dimensional slewing maneuvers of large flexible spacecraft. For this problem, the nominal solution is the optimal three-dimensional rigid body slew. The perturbation feedback then limits the deviations from this nominal solution due to the flexible body effects. The use of frequency shaping in both the nominal and perturbation feedback formulations reduces the excitation of high-frequency unmodeled modes. A modified Kalman filter is presented for estimating the plant states.

Fabrication of Nd3+ and Mn2+ ions Co-doped Spinal Strontium Nanoferrites for High Frequency Device Applications

NASA Astrophysics Data System (ADS)

Ahmad, Iqbal; Shah, Syed Mujtaba; Ashiq, Muhammad Naeem; Nawaz, Faisal; Shah, Afzal; Siddiq, Muhammad; Fahim, Iqra; Khan, Samiullah

2016-10-01

Microemulsion method has been used for the synthesis of high resistive spinal nanoferrites with nominal composition Sr1- x Nd x Fe2- y Mn y O4 (0.0 ≤ x ≤ 0.1, 0.0 ≤ y ≤ 1.0) for high frequency device applications. It has been confirmed by x-ray diffraction (XRD) results that these ferrites have a cubic spinal structure with a mean crystallite size ranging from 34 mm to 47 nm. The co-substitution of Nd3+ and Mn2+ ions was performed, and its effect on electrical, dielectric and impedance properties was analyzed employing direct current (DC) resistivity measurements, dielectric measurements and electrochemical impedance spectroscopy (EIS). The DC resistivity ( ρ) value was the highest for the composition Sr0.90Nd0.1FeMnO4, but for the same composition, dielectric parameters and alternating current (AC) conductivity showed their minimum values. In the lower frequency range, the magnitudes of dielectric parameters decrease with increasing frequency and show an almost independent frequency response at higher frequencies. Dielectric polarization has been employed to explain these results. It was inferred from the results of EIS that the conduction process in the studied ferrite materials is predominantly governed by grain boundary volume.

The Worldwide Interplanetary Scintillation (IPS) Stations (WIPSS) Network October 2016 Observing Campaign: Initial WIPSS Data Analyses

NASA Astrophysics Data System (ADS)

Bisi, M. M.; Fallows, R. A.; Jackson, B. V.; Tokumaru, M.; Gonzalez-Esparza, A.; Morgan, J.; Chashei, I. V.; Mejia-Ambriz, J.; Tyul'bashev, S. A.; Manoharan, P. K.; De la Luz, V.; Aguilar-Rodriguez, E.; Yu, H. S.; Barnes, D.; Chang, O.; Odstrcil, D.; Fujiki, K.; Shishov, V.

2017-12-01

Interplanetary Scintillation (IPS) allows for the determination of velocity and a proxy for plasma density to be made throughout the corona and inner heliosphere. Where sufficient observations are undertaken, the results can be used as input to the University of California, San Diego (UCSD) three-dimensional (3-D) time-dependent tomography suite to allow for the full 3-D reconstruction of both velocity and density throughout the inner heliosphere. By combining IPS results from multiple observing locations around the planet, we can increase both the temporal and spatial coverage across the whole of the inner heliosphere and hence improve forecast capability. During October 2016, a unique opportunity arose whereby the European-based LOw Frequency ARray (LOFAR) radio telescope was used to make nearly four weeks of continuous observations of IPS as a heliospheric space-weather trial campaign. This was expanded into a global effort to include observations of IPS from the Murchison Widefield Array (MWA) in Western Australia and many more observations from various IPS-dedicated WIPSS Network systems. LOFAR is a next-generation low-frequency radio interferometer capable of observing in the radio frequency range 10-250 MHz, nominally with up to 80 MHz bandwidth at a time. MWA in Western Australia is capable of observing in the 80-300 MHz frequency range nominally using up to 32 MHz of bandwidth. IPS data from LOFAR, ISEE, the MEXican Array Radio Telescope (MEXART), and, where possible, other WIPSS Network systems (such as LPI-BSA and Ooty), will be used in this study and we will present some initial findings for these data sets. We also make a first attempt at the 3-D reconstruction of multiple pertinent WIPSS results in the UCSD tomography. We will also try to highlight some of the potential future tools that make LOFAR a very unique system to be able to test and validate a whole plethora of IPS analysis methods with the same set of IPS data.

Concept for a lunar array for very low frequency radio astronomy

NASA Technical Reports Server (NTRS)

Marsh, Kenneth A.; Mahoney, Michael J.; Kuiper, Thomas B. H.; Jones, Dayton L.

1992-01-01

We discuss the design considerations relevant to a very low frequency array, to be deployed on the lunar near side during an early expedition. Such an array would operate in the frequency range 1-10 MHz, and would consist nominally of 20 antennas distributed over a region approximately 40 km in extent. Each antenna station would consist of a crossed-dipole antenna, together with a receiver, digitizer, solar cells, and batteries. In addition, the station will contain a UHF transmitter for relaying the digitized signal to a central station where it will be transmitted to Earth for subsequent processing, including cross-correlation with signals from other antennas. Each antenna station (including the central station) would be deployed as a self-contained unit, mounted on a miniature robotic vehicle. No fixed structures are required for the array.

Optical frequency comb Fourier transform spectroscopy with sub-nominal resolution and precision beyond the Voigt profile

NASA Astrophysics Data System (ADS)

Rutkowski, Lucile; Masłowski, Piotr; Johansson, Alexandra C.; Khodabakhsh, Amir; Foltynowicz, Aleksandra

2018-01-01

Broadband precision spectroscopy is indispensable for providing high fidelity molecular parameters for spectroscopic databases. We have recently shown that mechanical Fourier transform spectrometers based on optical frequency combs can measure broadband high-resolution molecular spectra undistorted by the instrumental line shape (ILS) and with a highly precise frequency scale provided by the comb. The accurate measurement of the power of the comb modes interacting with the molecular sample was achieved by acquiring single-burst interferograms with nominal resolution matched to the comb mode spacing. Here we describe in detail the experimental and numerical steps needed to achieve sub-nominal resolution and retrieve ILS-free molecular spectra, i.e. with ILS-induced distortion below the noise level. We investigate the accuracy of the transition line centers retrieved by fitting to the absorption lines measured using this method. We verify the performance by measuring an ILS-free cavity-enhanced low-pressure spectrum of the 3ν1 + ν3 band of CO2 around 1575 nm with line widths narrower than the nominal resolution. We observe and quantify collisional narrowing of absorption line shape, for the first time with a comb-based spectroscopic technique. Thus retrieval of line shape parameters with accuracy not limited by the Voigt profile is now possible for entire absorption bands acquired simultaneously.

Design and Study of a LOX/GH2 Throttleable Swirl Injector for Rocket Applications

NASA Technical Reports Server (NTRS)

Greene, Christopher; Woodward, Roger; Pal, Sibtosh; Santoro, Robert; Garcia, Roberto (Technical Monitor)

2002-01-01

A LOX/GH2 swirl injector was designed for a 10:1 propellant throttling range. To accomplish this, a dual LOX (liquid oxygen) manifold was used feeding a single common vortex chamber of the swirl element. Hot-fire experiments were conducting for rocket chamber pressures from 80 to 800 psia at a mixture ratio of nominally 6.0 using steady flow, single-point-per-firing cases as well as dynamic throttling conditions. Low frequency (mean) and high frequency (fluctuating) pressure transducer data, flow meter measurements, and Raman spectroscopy images for mixing information were obtained. The injector design, experimental setup, low frequency pressure data, and injector performance analysis will be presented. C efficiency was very high (approximately 100%) at the middle of the throttle-able range with somewhat lower performance at the high and low ends. From the analysis of discreet steady state operating conditions, injector pressure drop was slightly higher than predicted with an inviscid analysis, but otherwise agreed well across the design throttling range. Analysis of the dynamic throttling data indicates that the injector may experience transient conditions that effect pressure drop and performance when compared to steady state results.

Design and Study of a LOX/GH2 Throttleable Swirl Injector for Rocket Applications

NASA Technical Reports Server (NTRS)

Greene, Christopher; Woodward, Roger; Pal, Sibtosh; Santoro, Robert

2002-01-01

A LOX/GH2 swirl injector was designed for a 10:1 propellant throttling range. To accomplish this, a dual LOX manifold was used feeding a single common vortex chamber of the swirl element. Hot-fire experiments were conducted for rocket chamber pressures from 80 to 800 psia at a mixture ratio of nominally 6.0 using steady flow, single-point-per-firing cases as well as dynamic throttling conditions. Low frequency (mean) and high frequency (fluctuating) pressure transducer data, flow meter measurements, and Raman spectroscopy images for mixing information were obtained. The injector design, experimental setup, low frequency pressure data, and injector performance analysis are presented. C* efficiency was very high (approx. 100%) at the middle of the throttleable range with somewhat lower performance at the high and low ends. From the analysis of discreet steady state operating conditions, injector pressure drop was slightly higher than predicted with an inviscid analysis, but otherwise agreed well across the design throttling range. Dynamic throttling of this injector was attempted with marginal success due to the immaturity of the throttling control system. Although the targeted mixture ratio of 6.0 was not maintained throughout the dynamic throttling profile, the injector behaved well over the wide range of conditions.

Robust time and frequency domain estimation methods in adaptive control

NASA Technical Reports Server (NTRS)

Lamaire, Richard Orville

1987-01-01

A robust identification method was developed for use in an adaptive control system. The type of estimator is called the robust estimator, since it is robust to the effects of both unmodeled dynamics and an unmeasurable disturbance. The development of the robust estimator was motivated by a need to provide guarantees in the identification part of an adaptive controller. To enable the design of a robust control system, a nominal model as well as a frequency-domain bounding function on the modeling uncertainty associated with this nominal model must be provided. Two estimation methods are presented for finding parameter estimates, and, hence, a nominal model. One of these methods is based on the well developed field of time-domain parameter estimation. In a second method of finding parameter estimates, a type of weighted least-squares fitting to a frequency-domain estimated model is used. The frequency-domain estimator is shown to perform better, in general, than the time-domain parameter estimator. In addition, a methodology for finding a frequency-domain bounding function on the disturbance is used to compute a frequency-domain bounding function on the additive modeling error due to the effects of the disturbance and the use of finite-length data. The performance of the robust estimator in both open-loop and closed-loop situations is examined through the use of simulations.

Noise frame duration, masking potency and whiteness of temporal noise.

PubMed

Kukkonen, Heljä; Rovamo, Jyrki; Donner, Kristian; Tammikallio, Marja; Raninen, Antti

2002-09-01

Because of the limited contrast range, increasing the duration of the noise frame is often the only option for increasing the masking potency of external, white temporal noise. This, however, reduces the high-frequency cutoff beyond which noise is no longer white. This study was conducted to determine the longest noise frame duration that produces the strongest masking effect and still mimics white noise on the detection of sinusoidal flicker. Contrast energy thresholds (E(th)) were measured for flicker at 1.25 to 20 Hz in strong, purely temporal (spatially uniform), additive, external noise. The masking power of white external noise, characterized by its spectral density at zero frequency N0, increases with the duration of the noise frame. For short noise frame durations, E(th) increased in direct proportion to N0, keeping the nominal signal-to-noise ratio [SNR = (E(th)/N0)(0.5)] constant at threshold. The masking effect thus increased with the duration of the noise frame and the noise mimicked white noise. When noise frame duration and N0 increased further, the nominal SNR at threshold started to decrease, indicating that noise no longer mimicked white noise. The minimum number of noise frames per flicker cycle needed to mimic white noise decreased with increasing flicker frequency from 8.3 at 1.25 Hz to 1.6 at 20 Hz. The critical high-frequency cutoff of detection-limiting temporal noise in terms of noise frames per signal cycle depends on the temporal frequency of the signal. This is opposite to the situation in the spatial domain and must be taken into consideration when temporal signals are masked with temporal noise.

Preflight SL-1/SL-3 Skylab VHF ranging coverage (nominal TPI). Antenna and propagation studies for spacecraft systems, task E-531

NASA Technical Reports Server (NTRS)

Eisenhauer, D. R.; James, D. A.

1973-01-01

A preflight assessment of the Skylab VHF ranging coverage for the rendezvous portion of the nominal SL-1/SL-3 mission is reported, assuming a 27 July 1973 SL-3 launch. Data are based on a nominal attitude trajectory, which has the Saturn workshop in a solar inertial attitude throughout the rendezvous; the CSM terminal phase initiation maneuver is nominal. An addendum to this report is being prepared, which considers the effects of early and late TPI maneuvers. Curves are presented which show the variation in received power levels on both spacecraft-to-spacecraft links from about 600 n.mi. range to CSM and SWS station keeping. Appropriate threshold levels are shown on these received power curves to indicate zero circuit margins for the ranging function.

James Webb Space Telescope - L2 Communications for Science Data Processing

NASA Technical Reports Server (NTRS)

Johns, Alan; Seaton, Bonita; Gal-Edd, Jonathan; Jones, Ronald; Fatig, Curtis; Wasiak, Francis

2008-01-01

JWST is the first NASA mission at the second Lagrange point (L2) to identify the need for data rates higher than 10 megabits per second (Mbps). JWST will produce approximately 235 Gigabits of science data every day that will be downlinked to the Deep Space Network (DSN). To get the data rates desired required moving away from X-band frequencies to Ka-band frequencies. To accomplish this transition, the DSN is upgrading its infrastructure. This new range of frequencies are becoming the new standard for high data rate science missions at L2. With the new frequency range, the issues of alternatives antenna deployment, off nominal scenarios, NASA implementation of the Ka-band 26 GHz, and navigation requirements will be discussed in this paper. JWST is also using Consultative Committee for Space Data Systems (CCSDS) standard process for reliable file transfer using CCSDS File Delivery Protocol (CFDP). For JWST the use of the CFDP protocol provides level zero processing at the DSN site. This paper will address NASA implementations of Ground Stations in support of Ka-band 26 GHz and lesson learned from implementing a file base (CFDP) protocol operational system.

Solution-Based Electro-Orientation Spectroscopy (EOS) for Contactless Measurement of Semiconductor Nanowires

NASA Astrophysics Data System (ADS)

Yuan, Wuhan; Mohabir, Amar; Tutuncuoglu, Gozde; Filler, Michael; Feldman, Leonard; Shan, Jerry

2017-11-01

Solution-based, contactless methods for determining the electrical conductivity of nanowires and nanotubes have unique advantages over conventional techniques in terms of high throughput and compatibility with further solution-based processing and assembly methods. Here, we describe the solution-based electro-orientation spectroscopy (EOS) method, in which nanowire conductivity is measured from the AC-electric-field-induced alignment rate of the nanowire in a suspending fluid. The particle conductivity is determined from the measured crossover frequency between conductivity-dominated, low-frequency alignment to the permittivity-dominated, high-frequency regime. We discuss the extension of the EOS measurement range by an order-of-magnitude, taking advantage of the high dielectric constant of deionized water. With water and other fluids, we demonstrate that EOS can quantitatively characterize the electrical conductivities of nanowires over a 7-order-of-magnitude range, 10-5 to 102 S/m. We highlight the efficiency and utility of EOS for nanomaterial characterization by statistically characterizing the variability of semiconductor nanowires of the same nominal composition, and studying the connection between synthesis parameters and properties. NSF CBET-1604931.

A fiber-optic interferometer with subpicometer resolution for dc and low-frequency displacement measurement.

PubMed

Smith, D T; Pratt, J R; Howard, L P

2009-03-01

We have developed a fiber-optic interferometer optimized for best performance in the frequency range from dc to 1 kHz, with displacement linearity of 1% over a range of +/- 25 nm, and noise-limited resolution of 2 pm. The interferometer uses a tunable infrared laser source (nominal 1550 nm wavelength) with high amplitude and wavelength stability, low spontaneous self-emission noise, high sideband suppression, and a coherence control feature that broadens the laser linewidth and dramatically lowers the low-frequency noise in the system. The amplitude stability of the source, combined with the use of specially manufactured "bend-insensitive" fiber and all-spliced fiber construction, results in a robust homodyne interferometer system, which achieves resolution of 40 fm Hz(-1/2) above 20 Hz and approaches the shot-noise-limit of 20 fm Hz(-1/2) at 1 kHz for an optical power of 10 microW, without the need for differential detection. Here we describe the design and construction of the interferometer, as well as modes of operation, and demonstrate its performance.

Electron traps in Gd3Ga3Al2O12:Ce garnets doped with rare-earth ions

NASA Astrophysics Data System (ADS)

Khanin, V. M.; Rodnyi, P. A.; Wieczorek, H.; Ronda, C. R.

2017-05-01

The curves of thermally stimulated luminescence of Gd3Ga3Al2O12:Ce3+ ceramics (a nominally pure sample and samples doped with rare-earth ions) are measured in the temperature range of 80-550 K. The depth and the frequency factor of electron traps established by Eu and Yb impurities are determined. An energy-level diagram of rare-earth ions in the bandgap of Gd3Ga3Al2O12 is presented.

80-GHz MMIC HEMT Voltage-Controlled Oscillator

NASA Technical Reports Server (NTRS)

Samoska, Lorene; Radisic, Vesna; Micovic, Miro; Hu, Ming; Janke, Paul; Ngo, Catherine; Nguyen, Loi

2003-01-01

A voltage-controlled oscillator (VCO) that operates in the frequency range from 77.5 to 83.5 GHz has been constructed in the form of a monolithic microwave integrated circuit (MMIC) that includes high-electron-mobility transistors (HEMTs). This circuit is a prototype of electronically tunable signal sources in the 75-to-110-GHz range, needed for communication, imaging, and automotive radar applications, among others. This oscillator (see Figure 1) includes two AlInAs/GaInAs/InP HEMTs. One HEMT serves mainly as an oscillator gain element. The other HEMT serves mainly as a varactor for controlling the frequency: the frequency-control element is its gate-to-source capacitance, which is varied by changing its gate supply voltage. The gain HEMT is biased for class-A operation (meaning that current is conducted throughout the oscillation cycle). Grounded coplanar waveguides are used as impedance-matching transmission lines, the input and output matching being chosen to sustain oscillation and maximize output power. Air bridges are placed at discontinuities to suppress undesired slot electromagnetic modes. A high density of vias is necessary for suppressing a parallel-plate electromagnetic mode that is undesired because it can propagate energy into the MMIC substrate. Previous attempts at constructing HEMT-based oscillators yielded circuits with relatively low levels of output power and narrow tuning ranges. For example, one HEMT VCO reported in the literature had an output power of 7 dBm (.5 mW) and a tuning range 2-GHz wide centered approximately at a nominal frequency of 77 GHz. In contrast, as shown in Figure 2, the present MMIC HEMT VCO puts out a power of 12.5 dBm (.18 mW) or more over the 6-GHz-wide frequency range from 77.5 to 83.5 GHz

Transverse acoustic forcing of a round hydrodynamically self-excited jet

NASA Astrophysics Data System (ADS)

Kushwaha, Abhijit Kumar; Mazur, Marek; Worth, Nicholas; Dawson, James; Li, Larry K. B.

2017-11-01

Hydrodynamically self-excited jets can readily synchronize with longitudinal acoustic forcing, but their response to transverse acoustic forcing is less clear. In this experimental study, we apply transverse acoustic forcing to an axisymmetric low-density jet at frequencies around its natural global frequency. We place the jet in a rectangular box containing two loudspeakers, one at each end, producing nominally one-dimensional standing pressure waves. By traversing the jet across this box, we subject it to a range of acoustic modes, from purely longitudinal (streamwise) modes at the pressure anti-node to purely transverse (cross-stream) modes at the pressure node. Using time-resolved Background-Oriented Schlieren (BOS) imaging and hot-wire anemometry, we characterize the jet response for different forcing frequencies, amplitudes and mode shapes, providing new insight into the way transverse acoustic oscillations interact with axisymmetric hydrodynamic oscillations. This work was supported by the Research Grants Council of Hong Kong (Project No. 16235716 and 26202815).

Artificial ionospheric layers during pump frequency stepping near the 4th gyroharmonic at HAARP.

PubMed

Sergeev, E; Grach, S; Shindin, A; Mishin, E; Bernhardt, P; Briczinski, S; Isham, B; Broughton, M; LaBelle, J; Watkins, B

2013-02-08

We report on artificial descending plasma layers created in the ionosphere F region by high-power high-frequency (HF) radio waves from High-frequency Active Auroral Research Program at frequencies f(0) near the fourth electron gyroharmonic 4f(ce). The data come from concurrent measurements of the secondary escaping radiation from the HF-pumped ionosphere, also known as stimulated electromagnetic emission, reflected probing signals at f(0), and plasma line radar echoes. The artificial layers appeared only for injections along the magnetic field and f(0)>4f(ce) at the nominal HF interaction altitude in the background ionosphere. Their average downward speed ~0.5 km/s holds until the terminal altitude where the local fourth gyroharmonic matches f(0). The total descent increases with the nominal offset f(0)-4f(ce).

47 CFR 73.682 - TV transmission standards.

Code of Federal Regulations, 2012 CFR

2012-10-01

....682 Telecommunication FEDERAL COMMUNICATIONS COMMISSION (CONTINUED) BROADCAST RADIO SERVICES RADIO... frequency shall be nominally 1.25 MHz above the lower boundary of the channel. (3) The aural center frequency shall be 4.5 MHz higher than the visual carrier frequency. (4) The visual transmission amplitude...

47 CFR 73.682 - TV transmission standards.

Code of Federal Regulations, 2011 CFR

2011-10-01

....682 Telecommunication FEDERAL COMMUNICATIONS COMMISSION (CONTINUED) BROADCAST RADIO SERVICES RADIO... frequency shall be nominally 1.25 MHz above the lower boundary of the channel. (3) The aural center frequency shall be 4.5 MHz higher than the visual carrier frequency. (4) The visual transmission amplitude...

47 CFR 73.682 - TV transmission standards.

Code of Federal Regulations, 2013 CFR

2013-10-01

....682 Telecommunication FEDERAL COMMUNICATIONS COMMISSION (CONTINUED) BROADCAST RADIO SERVICES RADIO... frequency shall be nominally 1.25 MHz above the lower boundary of the channel. (3) The aural center frequency shall be 4.5 MHz higher than the visual carrier frequency. (4) The visual transmission amplitude...

47 CFR 73.682 - TV transmission standards.

Code of Federal Regulations, 2014 CFR

2014-10-01

....682 Telecommunication FEDERAL COMMUNICATIONS COMMISSION (CONTINUED) BROADCAST RADIO SERVICES RADIO... frequency shall be nominally 1.25 MHz above the lower boundary of the channel. (3) The aural center frequency shall be 4.5 MHz higher than the visual carrier frequency. (4) The visual transmission amplitude...

47 CFR 73.682 - TV transmission standards.

Code of Federal Regulations, 2010 CFR

2010-10-01

....682 Telecommunication FEDERAL COMMUNICATIONS COMMISSION (CONTINUED) BROADCAST RADIO SERVICES RADIO... frequency shall be nominally 1.25 MHz above the lower boundary of the channel. (3) The aural center frequency shall be 4.5 MHz higher than the visual carrier frequency. (4) The visual transmission amplitude...

Mechanical Energy Propagation and Backscattering in Nominally Dry Soil: Imaging Buried Land Mines

NASA Astrophysics Data System (ADS)

Sen, Surajit

2003-04-01

The imaging of shallow buried objects in a complex medium, e.g., nominally dry sand, is an outstanding challenge. Such imaging is of relevance in connection with the detection and subsequent imaging of buried non-metallic anti-personnel land mines and in other applications. It has been shown that gentle mechanical impulses and low frequency sound waves with frequencies roughly between 150-350 Hz or so can penetrate distances of up to a foot in sand. Hence, such signals can potentially be useful in the detection and perhaps in the imaging of shallow buried objects. It is presently unclear whether high frequency signals can be effectively used to image shallow buried objects. Impulses can typically penetrate larger distances into sand and soil. Both impulses and continuous sound waves can be used for imaging shallow buried objects. The talk shall briefly review the state-of-the-art in low frequency sound propagation in soil and shall discuss the current understanding of impulse propagation and backscattering in nominally dry sand beds. It will be argued that impulse based imaging may have the potential to be a simple and fast way to detect and image small non-metallic mines. Research supported by the National Science Foundation Grant No. NSF-CMS 0070055.

Ionospheric signatures of cusp latitude Pc 3 pulsations

NASA Technical Reports Server (NTRS)

Engebretson, M. J.; Anderson, B. J.; Cahill, L. J., Jr.; Arnoldy, R. L.; Rosenberg, T. J.

1990-01-01

Search coil magnetometer, riometer, photometer, and ELF-VLF receiver data obtained at South Pole Station and McMurdo, Antarctica during selected days in March and April 1986 are compared. Narrow-band magnetic pulsations in the Pc 3 period range are observed simultaneously at both stations in the dayside sector during times of low IMF cone angle, but are considerably stronger at South Pole, which is located at a latitude near the nominal foot point of the dayside cusp/cleft region. Pulsations in auroral light at 427.8 nm wavelength are often observed with magnetic pulsations at South Pole, but such optical pulsations are not observed at McMurdo. The observations suggest that precipitating magnetosheathlike electrons at nominal dayside cleft latitudes are at times modulated with frequencies similar to those of upstream waves. These particles may play an important role, via modification of ionospheric currents and conductivities, in the transmission of upstream wave signals into the magnetosphere and in the generation of dayside high-latitude Pc 3 pulsations.

Terahertz dielectric response of ferroelectric Ba(x)Sr(1-x)TiO3 thin films.

PubMed

Kang, Seung Beom; Kwak, Min Hwan; Choi, Muhan; Kim, Sungil; Kim, Taeyong; Cha, Eun Jong; Kang, Kwang Yong

2011-11-01

Terahertz time-domain spectroscopy has been used to investigate the dielectric and optical properties of ferroelectric Ba(x)Sr(1-x)TiO(3) thin films for nominal x-values of 0.4, 0.6, and 0.8 in the frequency range of 0.3 to 2.5 THz. The ferroelectric thin films were deposited at approximately 700 nm thickness on [001] MgO substrate by pulsed laser deposition. The measured complex dielectric and optical constants were compared with the Cole-Cole relaxation model. The results show that the Cole-Cole relaxation model fits well with the data throughout the frequency range and the dielectric relaxation behavior of ferroelectric Ba(x)Sr(1-x)TiO(3) thin films varies with the films compositions. Among the compositions of Ba(x)Sr(1-x)TiO(3) films with different Ba/Sr ratios, Ba(0.6)Sr(0.4)TiO(3) has the highest dielectric constants and the shortest dielectric relaxation time.

DOE Office of Scientific and Technical Information (OSTI.GOV)

Freemire, Ben; Bowring, Daniel; Kochemirovskiy, Alexey

Bright muon sources require six dimensional cooling to achieve acceptable luminosities. Ionization cooling is the only known method able to do so within the muon lifetime. One proposed cooling channel, the Helical Cooling Channel, utilizes gas filled radio frequency cavities to both mitigate RF breakdown in the presence of strong, external magnetic fields, and provide the cooling medium. Engineering constraints on the diameter of the magnets within which these cavities operate dictate the radius of the cavities be decreased at their nominal operating frequency. To accomplish this, one may load the cavities with a larger dielectric material. Alumina of puritiesmore » ranging from 96 to 99.8% was tested in a high pressure RF test cell at the MuCool Test Area at Fermilab. The results of breakdown studies with pure nitrogen gas, and oxygen-doped nitrogen gas indicate the peak surface electric field on the alumina ranges between 10 and 15 MV/m. How these results affect the design of a prototype cooling channel cavity will be discussed.« less

Turbulent Boundary Layers in Oscillating Flows. Part 1: an Experimental and Computational Study

NASA Technical Reports Server (NTRS)

Cook, W. J.

1986-01-01

An experimental-computational study of the behavior of turbulent boundary layers for oscillating air flows over a plane surface with a small favorable mean pressure gradient is described. Experimental studies were conducted for boundary layers generated on the test section wall of a facility that produces a flow with a mean free stream velocity and a superposed nearly-pure sinusoidal component over a wide range of frequency. Flow at a nominal mean free stream velocity of 50 m/s were studied at atmospheric pressure and temperature at selected axial positions over a 2 m test length for frequencies ranging from 4 to 29 Hz. Quantitative experimental results are presented for unsteady velocity profiles and longitudinal turbulence levels obtained from hot wire anemometer measurements at three axial positions. Mean velocity profiles for oscillating flows were found to exhibit only small deviations from corresponding steady flow profiles, while amplitudes and phase relationships exhibited a strong dependence on axial position and frequency. Since sinusoidal flows could be generated over a wide range of frequency, studies at fixed values of reduced frequency at different axial positions were studied. Results show that there is some utility in the use of reduced frequency to correlate unsteady velocity results. The turbulence level u' sub rms was observed to vary essentially sinusoidally around values close to those measured in steady flow. However, the amplitude of oscillation and phase relations for turbulence level were found to be strongly frequency dependent. Numerical predictions were obtained using an unsteady boundary layer computational code and the Cebeci-Smith and Glushko turbulence models. Predicted quantities related to unsteady velocity profiles exhibit fair agreement with experiment when the Cebeci-Smith turbulence model is used.

Beam dynamics and electromagnetic studies of a 3 MeV, 325 MHz radio frequency quadrupole accelerator

NASA Astrophysics Data System (ADS)

Gaur, Rahul; Kumar, Vinit

2018-05-01

We present the beam dynamics and electromagnetic studies of a 3 MeV, 325 MHz H- radio frequency quadrupole (RFQ) accelerator for the proposed Indian Spallation Neutron Source project. We have followed a design approach, where the emittance growth and the losses are minimized by keeping the tune depression ratio larger than 0.5. The transverse cross-section of RFQ is designed at a frequency lower than the operating frequency, so that the tuners have their nominal position inside the RFQ cavity. This has resulted in an improvement of the tuning range, and the efficiency of tuners to correct the field errors in the RFQ. The vane-tip modulations have been modelled in CST-MWS code, and its effect on the field flatness and the resonant frequency has been studied. The deterioration in the field flatness due to vane-tip modulations is reduced to an acceptable level with the help of tuners. Details of the error study and the higher order mode study along with mode stabilization technique are also described in the paper.

76 FR 25342 - Children's Health Protection Advisory Committee; Request for Nominations to the Children's Health...

Federal Register 2010, 2011, 2012, 2013, 2014

2011-05-04

... ENVIRONMENTAL PROTECTION AGENCY [FRL-9302-1] Children's Health Protection Advisory Committee; Request for Nominations to the Children's Health Protection Advisory Committee AGENCY: Environmental... nominations from a range of qualified candidates to be considered for appointment to its Children's Health...

A generalized Lyapunov theory for robust root clustering of linear state space models with real parameter uncertainty

NASA Technical Reports Server (NTRS)

Yedavalli, R. K.

1992-01-01

The problem of analyzing and designing controllers for linear systems subject to real parameter uncertainty is considered. An elegant, unified theory for robust eigenvalue placement is presented for a class of D-regions defined by algebraic inequalities by extending the nominal matrix root clustering theory of Gutman and Jury (1981) to linear uncertain time systems. The author presents explicit conditions for matrix root clustering for different D-regions and establishes the relationship between the eigenvalue migration range and the parameter range. The bounds are all obtained by one-shot computation in the matrix domain and do not need any frequency sweeping or parameter gridding. The method uses the generalized Lyapunov theory for getting the bounds.

Trampoline metamaterial: Local resonance enhancement by springboards

NASA Astrophysics Data System (ADS)

Bilal, Osama R.; Hussein, Mahmoud I.

2013-09-01

We investigate the dispersion characteristics of locally resonant elastic metamaterials formed by the erection of pillars on the solid regions in a plate patterned by a periodic array of holes. We show that these solid regions effectively act as springboards leading to an enhanced resonance behavior by the pillars when compared to the nominal case of pillars with no holes. This local resonance amplification phenomenon, which we define as the trampoline effect, is shown to cause subwavelength bandgaps to increase in size by up to a factor of 4. This outcome facilitates the utilization of subwavelength metamaterial properties over exceedingly broad frequency ranges.

The Role of Friendship Reciprocity in University Freshmen's Alcohol Consumption.

PubMed

Giese, Helge; Stok, F Marijn; Renner, Britta

2017-07-01

The similarity of friends in the frequency and quantity of alcohol consumption is explored. During their first semester, 57 psychology freshmen indicated weekly drinking frequency and quantity and nominated the three peers of this group they liked most. These nominations were then used to derive the weekly alcohol consumption of friends that either did or did not reciprocate a nomination. Multilevel modeling of weekly variations showed that individuals' drinking frequency was similar to peers who reciprocated a friendship (b = 0.15, p = .001), but not to non-reciprocating peers (b = -0.01, p = .720). In contrast, weekly variation in quantity of individual students' drinking was similar to both reciprocating (b = 0.11, p = .018) and non-reciprocating peers' drinking (b = 0.10, p = .014). Yet across all weeks, quantity tended only to be similar to non-reciprocating peers (b = 0.49, p = .020). Freshmen might spend drinking time with peers who reciprocate a friendship, but are similar regarding the quantity of drinks consumed to all people they find interesting. Thus, alcohol consumption is used strategically for social purposes. This social purpose should also be acknowledged in alcohol-reduction interventions. © 2017 The International Association of Applied Psychology.

Generating an AC amplitude magnetic flux density value up to 150 μT at a frequency up to 100 kHz

NASA Astrophysics Data System (ADS)

Ulvr, Michal; Polonský, Jakub

2017-05-01

AC magnetic field analyzers with a triaxial coil probe are widely used by health and safety professionals, in manufacturing, and in service industries. For traceable calibration of these analyzers, it is important to be able to generate a stable, homogeneous reference AC magnetic flux density (MFD). In this paper, the generating of AC amplitude MFD value of 150 μT by single-layer Helmholtz type solenoid, described in previous work, was expanded up to a frequency of 100 kHz using the effect of serial resonance. A programmable capacitor array has been developed with a range of adjustable values from 50 pF to 51225 pF. In addition, the multi-layer search coil with a nominal area turns value of 1.3m2, used for adjusting AC MFD in the solenoid, has been modified by a transimpedance amplifier for use in a wider frequency range than up to 3 kHz. The possibility of using the programmable capacitor array up to 150 kHz has also been tested. An AC amplitude MFD value of 150 μT can be generated with expanded uncertainty better than 0.6% up to 100 kHz.

Drifting oscillations in axion monodromy

DOE PAGES

Flauger, Raphael; McAllister, Liam; Silverstein, Eva; ...

2017-10-31

In this paper, we study the pattern of oscillations in the primordial power spectrum in axion monodromy inflation, accounting for drifts in the oscillation period that can be important for comparing to cosmological data. In these models the potential energy has a monomial form over a super-Planckian field range, with superimposed modulations whose size is model-dependent. The amplitude and frequency of the modulations are set by the expectation values of moduli fields. We show that during the course of inflation, the diminishing energy density can induce slow adjustments of the moduli, changing the modulations. We provide templates capturing the effectsmore » of drifting moduli, as well as drifts arising in effective field theory models based on softly broken discrete shift symmetries, and we estimate the precision required to detect a drifting period. A non-drifting template suffices over a wide range of parameters, but for the highest frequencies of interest, or for sufficiently strong drift, it is necessary to include parameters characterizing the change in frequency over the e-folds visible in the CMB. Finally, we use these templates to perform a preliminary search for drifting oscillations in a part of the parameter space in the Planck nominal mission data.« less

IMPACTS OF IMAGERY TEMPORAL FREQUENCES ON LAND-COVER CHANGE DETECTION MONITORING

EPA Science Inventory

An important consideration for monitoring land~cover (LC) change is the nominal temporal frequency of remote sensor data acquisitions required to adequately characterize change events, Ecosystem specific regeneration rates are an important consideration for determining the requir...

Frequency Splitting Analysis and Compensation Method for Inductive Wireless Powering of Implantable Biosensors.

PubMed

Schormans, Matthew; Valente, Virgilio; Demosthenous, Andreas

2016-08-04

Inductive powering for implanted medical devices, such as implantable biosensors, is a safe and effective technique that allows power to be delivered to implants wirelessly, avoiding the use of transcutaneous wires or implanted batteries. Wireless powering is very sensitive to a number of link parameters, including coil distance, alignment, shape, and load conditions. The optimum drive frequency of an inductive link varies depending on the coil spacing and load. This paper presents an optimum frequency tracking (OFT) method, in which an inductive power link is driven at a frequency that is maintained at an optimum value to ensure that the link is working at resonance, and the output voltage is maximised. The method is shown to provide significant improvements in maintained secondary voltage and system efficiency for a range of loads when the link is overcoupled. The OFT method does not require the use of variable capacitors or inductors. When tested at frequencies around a nominal frequency of 5 MHz, the OFT method provides up to a twofold efficiency improvement compared to a fixed frequency drive. The system can be readily interfaced with passive implants or implantable biosensors, and lends itself to interfacing with designs such as distributed implanted sensor networks, where each implant is operating at a different frequency.

Ambiguities in spaceborne synthetic aperture radar systems

NASA Technical Reports Server (NTRS)

Li, F. K.; Johnson, W. T. K.

1983-01-01

An examination of aspects of spaceborne SAR time delay and Doppler ambiguities has led to the formulation of an accurate method for the evaluation of the ratio of ambiguity intensities to that of the signal, which has been applied to the nominal SAR system on Seasat. After discussing the variation of this ratio as a function of orbital latitude and attitude control error, it is shown that the detailed range migration-azimuth phase history of an ambiguity is different from that of a signal, so that the images of ambiguities are dispersed. Seasat SAR dispersed images are presented, and their dispersions are eliminated through an adjustment of the processing parameters. A method is also presented which uses a set of multiple pulse repetition sequences to determine the Doppler centroid frequency absolute values for SARs with high carrier frequencies and poor attitude measurements.

Kalman Filter Input Processor for Boresight Calibration

NASA Technical Reports Server (NTRS)

Strekalov, Dmitry; Kruizinga, Gerhard; Paik, Meegyeong; Yuan, Dah-Ning; Asmar, Sami W.

2014-01-01

Ka-band ranging provides the phase center (PC) to phase center range, which needs to be converted to the center of mass (CM) to center of mass range. Nominally, both PC and CM lie on the line connecting the spacecraft GRAIL A and GRAIL B. In this case, the conversion should be done simply by adding the CM-to-PC distance L to the measured range for both spacecraft. However, due to various technical reasons, such as displacement of the true CM from its nominal position in the SRF, or spacecraft attitude fluctuations, the PC and CM define a unit vector that may be different from the nominal line of sight. The objectives of the software are to determine the actual line of sight direction for each spacecraft and correct the previously recorded range data, and to provide instructions for how to maneuver each spacecraft to make necessary attitude corrections.

Reconfigurable Array Antenna Using Microelectromechanical Systems (MEMS) Actuators

NASA Technical Reports Server (NTRS)

Simons, Rainee N.; Chun, Donghoon; Katehi, Linda P. B.

2001-01-01

The paper demonstrates a patch antenna integrated with a novel microelectromechanical systems (MEMS) actuator for reconfiguring the operating frequency. Experimental results demonstrate that the center frequency can be reconfigured by as much as 1.6 percent of the nominal operating frequency at K-Band In addition, a novel on-wafer antenna pattern measurement technique is demonstrated.

76 FR 17992 - Information Reporting Program Advisory Committee (IRPAC); Nominations

Federal Register 2010, 2011, 2012, 2013, 2014

2011-03-31

... and other IRS leadership to provide recommendations on a wide range of information reporting... universities, securities, payroll, financial institutions and other industries. DATES: Written nominations must...

Reliability testing of ultra-low noise InGaAs quad photoreceivers

NASA Astrophysics Data System (ADS)

Joshi, Abhay M.; Datta, Shubhashish; Prasad, Narasimha; Sivertz, Michael

2018-02-01

We have developed ultra-low noise quadrant InGaAs photoreceivers for multiple applications ranging from Laser Interferometric Gravitional Wave Detection, to 3D Wind Profiling. Devices with diameters of 0.5 mm, 1mm, and 2 mm were processed, with the nominal capacitance of a single quadrant of a 1 mm quad photodiode being 2.5 pF. The 1 mm diameter InGaAs quad photoreceivers, using a low-noise, bipolar-input OpAmp circuitry exhibit an equivalent input noise per quadrant of <1.7 pA/√Hz in 2 to 20 MHz frequency range. The InGaAs Quad Photoreceivers have undergone the following reliability tests: 30 MeV Proton Radiation up to a Total Ionizing Dose (TID) of 50 krad, Mechanical Shock, and Sinusoidal Vibration.

ACOSS Eight (Active Control of Space Structures), Phase 2

DTIC Science & Technology

1981-09-01

A-2 A-2 Nominal Model - Equipment Section and Solar Panels ....... A-3 A-3 Nominal Model - Upper Support .-uss ...... ............ A-4 A...sensitivity analysis technique ef selecting critical system parameters is applied tc the Diaper tetrahedral truss structure (See Section 4-2...and solar panels are omitted. The precision section is mounted on isolators to inertially r•" I fixed rigid support. The mode frequencies of this

Low-frequency noise from large wind turbines.

PubMed

Møller, Henrik; Pedersen, Christian Sejer

2011-06-01

As wind turbines get larger, worries have emerged that the turbine noise would move down in frequency and that the low-frequency noise would cause annoyance for the neighbors. The noise emission from 48 wind turbines with nominal electric power up to 3.6 MW is analyzed and discussed. The relative amount of low-frequency noise is higher for large turbines (2.3-3.6 MW) than for small turbines (≤ 2 MW), and the difference is statistically significant. The difference can also be expressed as a downward shift of the spectrum of approximately one-third of an octave. A further shift of similar size is suggested for future turbines in the 10-MW range. Due to the air absorption, the higher low-frequency content becomes even more pronounced, when sound pressure levels in relevant neighbor distances are considered. Even when A-weighted levels are considered, a substantial part of the noise is at low frequencies, and for several of the investigated large turbines, the one-third-octave band with the highest level is at or below 250 Hz. It is thus beyond any doubt that the low-frequency part of the spectrum plays an important role in the noise at the neighbors. © 2011 Acoustical Society of America

Telemetry Standards, RCC Standard 106-17. Chapter 3. Frequency Division Multiplexing Telemetry Standards

DTIC Science & Technology

2017-07-01

any of the listed reference frequencies may be used provided the requirements for compensation rate of change are satisfied. If the reference...for in present discriminator systems when the nominal response rating of the channels is employed and a reference frequency is recorded with the...Telemetry Standards, RCC Standard 106-17 Chapter 3, July 2017 3-i CHAPTER 3 Frequency Division Multiplexing Telemetry Standards Acronyms

Space Shuttle Main Engine Off-Nominal Low Power Level Operation

NASA Technical Reports Server (NTRS)

Bradley, Michael

1997-01-01

This paper describes Rocketdyne's successful analysis and demonstration of the Space Shuttle Main Engine (SSME) operation at off-nominal power levels during Reusable Launch Vehicle (RLV) evaluation tests. The nominal power level range for the SSME is from 65% rated power level (RPL) to 109% RPL. Off-nominal power levels incrementally demonstrated were: 17% RPL, 22% RPL, 27% RPL, 40% RPL, 45% RPL, and 50% RPL. Additional achievements during low power operation included: use of a hydrostatic bearing High Pressure Oxidizer Turbopump (HPOTP), nominal High Pressure Fuel Turbopump (HPFTP) first rotor critical speed operation, combustion stability at low power levels, and refined definition of nozzle flow separation heat loads.

Imposex and novel mechanisms of reproductive failure induced by tributyltin (TBT) in the freshwater snail Pomacea canaliculata.

PubMed

Giraud-Billoud, Maximiliano; Vega, Israel A; Wuilloud, Rodolfo G; Clément, María E; Castro-Vazquez, Alfredo

2013-10-01

The effects of tributyltin (TBT) on mortality and reproduction were studied in the invasive snail Pomacea canaliculata. The nominal median lethal concentration (LC50) was 9 µg TBT/L, after 28 d. The nominal no-observed effect on lethality concentration (NOECL) was 6 µg TBT/L after the same period. Male-female couples and females that had been group-mated but were isolated from males during the experiment (isolated females) were exposed (for 28 d) to either 0 µg/L or 6 µg/L of TBT (nominal NOECL-exposed). Copulation and oviposition frequencies, egg clutch mass, and percentage of egg fertility were recorded. Gonads (both sexes) and the seminal receptacle (females) were studied histologically at the end of the experiment. A significant decrease in copulation frequency was observed in mated-exposed females. Exposure also decreased oviposition frequency of mated-exposed and isolated-exposed females, but only the latter reached significance. No differences in either egg clutch mass or percentage of fertility were observed at first oviposition, but both parameters were drastically reduced in subsequent egg clutches of exposed females. No histological alterations were observed in gonads of TBT-exposed animals; however, sperm storage in the seminal receptacle was drastically decreased in exposed females. Imposex but no oviductal obstruction was observed in all exposed females. It is concluded that TBT induces reproductive failure in P. canaliculata by decreasing copulation frequency and by severely affecting sperm storage by the female. © 2013 SETAC.

Coaxial Cables for Martian Extreme Temperature Environments

NASA Technical Reports Server (NTRS)

Ramesham, Rajeshuni; Harvey, Wayne L.; Valas, Sam; Tsai, Michael C.

2011-01-01

Work was conducted to validate the use of the rover external flexible coaxial cabling for space under the extreme environments to be encountered during the Mars Science Laboratory (MSL) mission. The antennas must survive all ground operations plus the nominal 670-Martian-day mission that includes summer and winter seasons of the Mars environment. Successful development of processes established coaxial cable hardware fatigue limits, which were well beyond the expected in-flight exposures. In keeping with traditional qualification philosophy, this was accomplished by subjecting flight-representative coaxial cables to temperature cycling of the same depth as expected in-flight, but for three times the expected number of in-flight thermal cycles. Insertion loss and return loss tests were performed on the coaxial cables during the thermal chamber breaks. A vector network analyzer was calibrated and operated over the operational frequency range 7.145 to 8.450 GHz. Even though some of the exposed cables function only at UHF frequencies (approximately 400 MHz), the testing was more sensitive, and extending the test range down to 400 MHz would have cost frequency resolution. The Gore flexible coaxial cables, which were the subject of these tests, proved to be robust and displayed no sign of degradation due to the 3X exposure to the punishing Mars surface operations cycles.

Admittance–voltage profiling of Al{sub x}Ga{sub 1−x}N/GaN heterostructures: Frequency dependence of capacitance and conductance

DOE Office of Scientific and Technical Information (OSTI.GOV)

Köhler, K.; Pletschen, W.; Godejohann, B.

2015-11-28

Admittance–voltage profiling of Al{sub x}Ga{sub 1−x}N/GaN heterostructures was used to determine the frequency dependent capacitance and conductance of FET devices in the frequency range from 50 Hz to 1 MHz. The nominally undoped low pressure metal-organic vapor-phase epitaxy structures were grown with an Al-content of 30%. An additional 1 nm thick AlN interlayer was placed in one structure before the Al{sub 0.3}Ga{sub 0.7}N layer growth. For frequencies below 10{sup 8} Hz it is convenient to use equivalent circuits to represent electric or dielectric properties of a material, a method widely used, for example, in impedance spectroscopy. We want to emphasize the relation betweenmore » frequency dependent admittance–voltage profiling and the corresponding equivalent circuits to the complex dielectric function. Debye and Drude models are used for the description of the frequency dependent admittance profiles in a range of depletion onset of the two-dimensional electron gas. Capacitance- and conductance-frequency profiles are fitted in the entire measured range by combining both models. Based on our results, we see contributions to the two-dimensional electron gas for our samples from surface states (80%) as well as from background doping in the Al{sub 0.3}Ga{sub 0.7}N barriers (20%). The specific resistance of the layers below the gate is above 10{sup 5} Ω cm for both samples and increases with increasing negative bias, i.e., the layers below the gate are essentially depleted. We propose that the resistance due to free charge carriers, determined by the Drude model, is located between gate and drain and, because of the AlN interlayer, the resistance is lowered by a factor of about 30 if compared to the sample without an AlN layer.« less

78 FR 42543 - Call for Nominations for the Rio Grande Natural Area Commission, Colorado

Federal Register 2010, 2011, 2012, 2013, 2014

2013-07-16

...: Send completed Council nominations to Tom Heinlein, District Manager, BLM Front Range District Office, 3028 East Main St., Ca[ntilde]on City, CO 81212. FOR FURTHER INFORMATION CONTACT: Tom Heinlein...

Process Options for Nominal 2-K Helium Refrigeration System Designs

DOE Office of Scientific and Technical Information (OSTI.GOV)

Peter Knudsen, Venkatarao Ganni

Nominal 2-K helium refrigeration systems are frequently used for superconducting radio frequency and magnet string technologies used in accelerators. This paper examines the trade-offs and approximate performance of four basic types of processes used for the refrigeration of these technologies; direct vacuum pumping on a helium bath, direct vacuum pumping using full or partial refrigeration recovery, cold compression, and hybrid compression (i.e., a blend of cold and warm sub-atmospheric compression).

Robust Crossfeed Design for Hovering Rotorcraft

NASA Technical Reports Server (NTRS)

Catapang, David R.

1993-01-01

Control law design for rotorcraft fly-by-wire systems normally attempts to decouple angular responses using fixed-gain crossfeeds. This approach can lead to poor decoupling over the frequency range of pilot inputs and increase the load on the feedback loops. In order to improve the decoupling performance, dynamic crossfeeds may be adopted. Moreover, because of the large changes that occur in rotorcraft dynamics due to small changes about the nominal design condition, especially for near-hovering flight, the crossfeed design must be 'robust'. A new low-order matching method is presented here to design robust crossfeed compensators for multi-input, multi-output (MIMO) systems. The technique identifies degrees-of-freedom that can be decoupled using crossfeeds, given an anticipated set of parameter variations for the range of flight conditions of concern. Cross-coupling is then reduced for degrees-of-freedom that can use crossfeed compensation by minimizing off-axis response magnitude average and variance. Results are presented for the analysis of pitch, roll, yaw and heave coupling of the UH-60 Black Hawk helicopter in near-hovering flight. Robust crossfeeds are designed that show significant improvement in decoupling performance and robustness over nominal, single design point, compensators. The design method and results are presented in an easily used graphical format that lends significant physical insight to the design procedure. This plant pre-compensation technique is an appropriate preliminary step to the design of robust feedback control laws for rotorcraft.

Observations of frequency shift associated with schooling fish

NASA Astrophysics Data System (ADS)

Diachok, Orest

2003-04-01

The number of sardines per school, N, is nominally 10000 and the separation between sardines in school, s, is nominally 1 fish length, L.s is much smaller than the wavelength at f (the resonance frequency of individuals), which suggests that schools may exhibit acoustic properties of bubble clouds. Long-term, broadband transmission loss measurements at a shallow-water site in the Gulf of Lion revealed absorption lines due to dispersed sardines at 1.3 kHz at 20 m at night and 2.7 kHz at 65 m at dawn. Temporal changes in observed values of f were consistent with concurrent echo sounder observations of the vertical migration of sardines, and theoretical computations based on laboratory measurements of swim bladder dimensions. The measured resonance frequency of sardines in schools during daytime, 1.7 kHz at 65 m, was 0.6f at the same depth at dawn. The observed frequency shift is consistent with a hybrid model of the fundamental resonance frequency of a bubble cloud, which is based on theories developed by Feuillade, Nero, and Love (1996) and dAgostino and Brennan (1988), and s=0.8 L and N=5000 fish per school. [Work supported by ONR.

Microelectromechanical Systems (MEMS) Actuators for Antenna Reconfigurability

NASA Technical Reports Server (NTRS)

Simons, Rainee N.; Chun, Donghoon; Katehi, Linda P. B.

2001-01-01

A novel microelectromechanical systems (MEMS) actuator for patch antenna reconfiguration, is presented for the first time. A key feature is the capability of multi-band operation without greatly increasing the antenna element dimensions. Experimental results demonstrate that the center frequency can be reconfigured from few hundred MHz to few GHz away from the nominal operating frequency.

Plural Acquisition in Children with Specific Language Impairment.

ERIC Educational Resources Information Center

Oetting, Janna B.; Rice, Mabel L.

1993-01-01

A plural elicitation task and a nominal compounding task were administered to 18 children (age 5-6 years) with specific language impairment (SLI) and 2 control groups. SLI children's performance was affected by input frequency; three explanations within a model of linguistic normalcy are proposed to account for this frequency effect. (Author/DB)

Underwater sound radiation patterns of contemporary merchant ships

NASA Astrophysics Data System (ADS)

Gassmann, M.; Wiggins, S. M.; Hildebrand, J. A.

2016-12-01

Merchant ships radiate underwater sound as an unintended by-product of their operation and as consequence contribute significantly to low-frequency, man-made noise in the ocean. Current measurement standards for the description of underwater sound from ships (ISO 17208-1:2016 and ANSI S12.64-2009) require nominal hydrophone depths of 15°, 30° and 45° at the starboard and portside of the test vessel.To opportunistically study the underwater sound of contemporary merchant ships that were tracked by the Automatic Identification System (AIS), an array of seven high-frequency acoustic recording packages (HARPs) with a sampling frequency of 200 kHz was deployed in the Santa Barbara Channel in the primary outgoing shipping lane for the port of Los Angeles and Long Beach. The vertical and horizontal aperture of the array allowed for starboard and portside measurements at all standard-required nominal hydrophone depths in addition to measurements taken at the keel aspect. Based on these measurements, frequency-dependent radiation patterns of contemporary merchant ships were estimated and used to evaluate current standards for computing ship source levels.

High frequency pacing of edge localized modes by injection of lithium granules in DIII-D H-mode discharges

DOE Office of Scientific and Technical Information (OSTI.GOV)

Bortolon, A.; Maingi, R.; Mansfield, D. K.

A newly installed Lithium Granule Injector (LGI) was used to pace edge localized modes (ELM) in DIII-D. ELM pacing efficiency was studied injecting lithium granules of nominal diameter 0.3–0.9mm, speed of 50–120 m s -1 and average injection rates up to 100 Hz for 0.9mm granules and up to 700 Hz for 0.3mm granules. The efficiency of ELM triggering was found to depend strongly on size of the injected granules, with triggering efficiency close to 100% obtained with 0.9mm diameter granules, lower with smaller sizes, and weakly depending on granule velocity. Robust ELM pacing was demonstrated in ITER-like plasmas formore » the entire shot length, at ELM frequencies 3–5 times larger than the ‘natural’ ELM frequency observed in reference discharges. Within the range of ELM frequencies obtained, the peak ELM heat flux at the outer strike point was reduced with increasing pacing frequency. The peak heat flux reduction at the inner strike point appears to saturate at high pacing frequency. Lithium was found in the plasma core, with a concurrent reduction of metallic impurities and carbon. Altogether, high frequency ELM pacing using the lithium granule injection appears to be compatible with both H-mode energy confinement and attractive H-mode pedestal characteristics, but further assessment is need« less

High frequency pacing of edge localized modes by injection of lithium granules in DIII-D H-mode discharges

DOE PAGES

Bortolon, A.; Maingi, R.; Mansfield, D. K.; ...

2016-04-08

A newly installed Lithium Granule Injector (LGI) was used to pace edge localized modes (ELM) in DIII-D. ELM pacing efficiency was studied injecting lithium granules of nominal diameter 0.3–0.9mm, speed of 50–120 m s -1 and average injection rates up to 100 Hz for 0.9mm granules and up to 700 Hz for 0.3mm granules. The efficiency of ELM triggering was found to depend strongly on size of the injected granules, with triggering efficiency close to 100% obtained with 0.9mm diameter granules, lower with smaller sizes, and weakly depending on granule velocity. Robust ELM pacing was demonstrated in ITER-like plasmas formore » the entire shot length, at ELM frequencies 3–5 times larger than the ‘natural’ ELM frequency observed in reference discharges. Within the range of ELM frequencies obtained, the peak ELM heat flux at the outer strike point was reduced with increasing pacing frequency. The peak heat flux reduction at the inner strike point appears to saturate at high pacing frequency. Lithium was found in the plasma core, with a concurrent reduction of metallic impurities and carbon. Altogether, high frequency ELM pacing using the lithium granule injection appears to be compatible with both H-mode energy confinement and attractive H-mode pedestal characteristics, but further assessment is need« less

Comparison of Ordinal and Nominal Classification Trees to Predict Ordinal Expert-Based Occupational Exposure Estimates in a Case–Control Study

PubMed Central

Wheeler, David C.; Archer, Kellie J.; Burstyn, Igor; Yu, Kai; Stewart, Patricia A.; Colt, Joanne S.; Baris, Dalsu; Karagas, Margaret R.; Schwenn, Molly; Johnson, Alison; Armenti, Karla; Silverman, Debra T.; Friesen, Melissa C.

2015-01-01

Objectives: To evaluate occupational exposures in case–control studies, exposure assessors typically review each job individually to assign exposure estimates. This process lacks transparency and does not provide a mechanism for recreating the decision rules in other studies. In our previous work, nominal (unordered categorical) classification trees (CTs) generally successfully predicted expert-assessed ordinal exposure estimates (i.e. none, low, medium, high) derived from occupational questionnaire responses, but room for improvement remained. Our objective was to determine if using recently developed ordinal CTs would improve the performance of nominal trees in predicting ordinal occupational diesel exhaust exposure estimates in a case–control study. Methods: We used one nominal and four ordinal CT methods to predict expert-assessed probability, intensity, and frequency estimates of occupational diesel exhaust exposure (each categorized as none, low, medium, or high) derived from questionnaire responses for the 14983 jobs in the New England Bladder Cancer Study. To replicate the common use of a single tree, we applied each method to a single sample of 70% of the jobs, using 15% to test and 15% to validate each method. To characterize variability in performance, we conducted a resampling analysis that repeated the sample draws 100 times. We evaluated agreement between the tree predictions and expert estimates using Somers’ d, which measures differences in terms of ordinal association between predicted and observed scores and can be interpreted similarly to a correlation coefficient. Results: From the resampling analysis, compared with the nominal tree, an ordinal CT method that used a quadratic misclassification function and controlled tree size based on total misclassification cost had a slightly better predictive performance that was statistically significant for the frequency metric (Somers’ d: nominal tree = 0.61; ordinal tree = 0.63) and similar performance for the probability (nominal = 0.65; ordinal = 0.66) and intensity (nominal = 0.65; ordinal = 0.65) metrics. The best ordinal CT predicted fewer cases of large disagreement with the expert assessments (i.e. no exposure predicted for a job with high exposure and vice versa) compared with the nominal tree across all of the exposure metrics. For example, the percent of jobs with expert-assigned high intensity of exposure that the model predicted as no exposure was 29% for the nominal tree and 22% for the best ordinal tree. Conclusions: The overall agreements were similar across CT models; however, the use of ordinal models reduced the magnitude of the discrepancy when disagreements occurred. As the best performing model can vary by situation, researchers should consider evaluating multiple CT methods to maximize the predictive performance within their data. PMID:25433003

Friction Stir Process Mapping Methodology

NASA Technical Reports Server (NTRS)

Bjorkman, Gerry; Kooney, Alex; Russell, Carolyn

2003-01-01

The weld process performance for a given weld joint configuration and tool setup is summarized on a 2-D plot of RPM vs. IPM. A process envelope is drawn within the map to identify the range of acceptable welds. The sweet spot is selected as the nominal weld schedule The nominal weld schedule is characterized in the expected manufacturing environment. The nominal weld schedule in conjunction with process control ensures a consistent and predictable weld performance.

On the long range propagation of sound over irregular terrain

NASA Technical Reports Server (NTRS)

Howe, M. S.

1984-01-01

The theory of sound propagation over randomly irregular, nominally plane terrain of finite impedance is discussed. The analysis is an extension of the theory of coherent scatter originally proposed by Biot for an irregular rigid surface. It combines Biot's approach, wherein the surface irregularities are modeled by a homogeneous distribution of hemispherical bosses, with more conventional analyses in which the ground is modeled as a smooth plane of finite impedance. At sufficiently low frequencies the interaction of the surface irregularities with the nearfield of a ground-based source leads to the production of surface waves, which are effective in penetrating the ground shadow zone predicted for a smooth surface of the same impedance.

Analysis of the Emitted Wavelet of High-Resolution Bowtie GPR Antennas

PubMed Central

Rial, Fernando I.; Lorenzo, Henrique; Pereira, Manuel; Armesto, Julia

2009-01-01

Most Ground Penetrating Radars (GPR) cover a wide frequency range by emitting very short time wavelets. In this work, we study in detail the wavelet emitted by two bowtie GPR antennas with nominal frequencies of 800 MHz and 1 GHz. Knowledge of this emitted wavelet allows us to extract as much information as possible from recorded signals, using advanced processing techniques and computer simulations. Following previously published methodology used by Rial et al. [1], which ensures system stability and reliability in data acquisition, a thorough analysis of the wavelet in both time and frequency domain is performed. Most of tests were carried out with air as propagation medium, allowing a proper analysis of the geometrical attenuation factor. Furthermore, we attempt to determine, for each antenna, a time zero in the records to allow us to correctly assign a position to the reflectors detected by the radar. Obtained results indicate that the time zero is not a constant value for the evaluated antennas, but instead depends on the characteristics of the material in contact with the antenna. PMID:22408523

Friction Stir Process Mapping Methodology

NASA Technical Reports Server (NTRS)

Kooney, Alex; Bjorkman, Gerry; Russell, Carolyn; Smelser, Jerry (Technical Monitor)

2002-01-01

In FSW (friction stir welding), the weld process performance for a given weld joint configuration and tool setup is summarized on a 2-D plot of RPM vs. IPM. A process envelope is drawn within the map to identify the range of acceptable welds. The sweet spot is selected as the nominal weld schedule. The nominal weld schedule is characterized in the expected manufacturing environment. The nominal weld schedule in conjunction with process control ensures a consistent and predictable weld performance.

High-Temperature Dielectric Properties of Aluminum Nitride Ceramic for Wireless Passive Sensing Applications

PubMed Central

Liu, Jun; Yuan, Yukun; Ren, Zhong; Tan, Qiulin; Xiong, Jijun

2015-01-01

The accurate characterization of the temperature-dependent permittivity of aluminum nitride (AlN) ceramic is quite critical to the application of wireless passive sensors for harsh environments. Since the change of the temperature-dependent permittivity will vary the ceramic-based capacitance, which can be converted into the change of the resonant frequency, an LC resonator, based on AlN ceramic, is prepared by the thick film technology. The dielectric properties of AlN ceramic are measured by the wireless coupling method, and discussed within the temperature range of 12 °C (room temperature) to 600 °C. The results show that the extracted relative permittivity of ceramic at room temperature is 2.3% higher than the nominal value of 9, and increases from 9.21 to 10.79, and the quality factor Q is decreased from 29.77 at room temperature to 3.61 at 600 °C within the temperature range. PMID:26370999

Low loss factor Co{sub 2}Z ferrite composites with equivalent permittivity and permeability for ultra-high frequency applications

DOE Office of Scientific and Technical Information (OSTI.GOV)

Su, Zhijuan; Chang, Hong; Sokolov, Alexander S.

2014-08-11

Ferrite composites of nominal composition Ba{sub 3}Co{sub 2+x}Ir{sub x}Fe{sub 24−2x}O{sub 41} were studied in order to achieve low magnetic and dielectric losses and equivalent permittivity and permeability over a frequency range of 0.3–1 GHz. Crystallographic structure was characterized by X-ray diffraction, which revealed a Z-type phase accompanied by increasing amounts of Y-type phase as the iridium amount was increased. The measured microwave dielectric and magnetic properties showed that the loss tan δ{sub ε} and loss tan δ{sub μ} decreased by 80% and 90% at 0.8 GHz with the addition of iridium of x = 0.12 and 0.15, respectively. An effective medium approximation was adopted to analyzemore » the composite ferrites having mixed phase structures. Moreover, adding Bi{sub 2}O{sub 3} enabled equivalent values of real permittivity and real permeability over the studied frequency range. The resultant data give rise to low loss factors, i.e., tan δ{sub ε}/ε′ = 0.008 and tan δ{sub μ}/μ′ = 0.037 at 0.8 GHz, while characteristic impedance was the same as that of free space.« less

Characterizing Extreme Environments for Army Testing

DTIC Science & Technology

2004-12-01

necessary to evaluate the plain, upland), well-developed and variable soil capability to conduct a specific test at a given location. profiles ( oxisols ...m) to medium (up to 20m) width streams, with nominal nominal velocities (ងm/s). Soils: Oxisols , ultisols, inceptisols, minimum depth in the range

Public Risk Assessment of Off-Nominal Genesis Entries

NASA Technical Reports Server (NTRS)

Mendeck, Gavin F.; Kadwa, Binaifer

2006-01-01

Public risk estimations were among the preparations for the entry of the Genesis sample return capsule. Personnel at the Johnson Space Center were requested to provide estimates of the public risk of off-nominal entries. These scenarios dealt with an incomplete trajectory maneuver that would result in the capsule landing outside of the controlled Utah Test and Training Range. Using a conservative approach to the inputs and assumptions, such off-nominal entries were demonstrated to fall within the project risk limits.

Increased Jet Noise Due to a "Nominally Laminar" State of Nozzle Exit Boundary Layer

NASA Technical Reports Server (NTRS)

Zaman, K. B. M. Q.

2017-01-01

A set of 2-in. diameter nozzles is used to investigate the effect of varying exit boundary layer state on the radiated noise from high-subsonic jets. It is confirmed that nozzles involving turbulent boundary layers are the quietest while nozzles involving a "nominally laminar" boundary layer are loud especially on the high-frequency side of the sound pressure level spectrum. The latter boundary layer state involves a "Blasius-like" mean velocity profile but higher turbulence intensities compared to those in the turbulent state. The higher turbulence in the initial region of the jet shear layer leads to increased high-frequency noise. The results strongly suggest that an anomaly noted with subsonic jet noise databases in the literature is due to a similar effect of differences in the initial boundary layer state.

Increased Jet Noise Due to a "Nominally Laminar" State of Nozzle Exit Boundary Layer

NASA Technical Reports Server (NTRS)

Zaman, K. B. M. Q.

2017-01-01

A set of 2-inch diameter nozzles is used to investigate the effect of varying exit boundary layer state on the radiated noise from high-subsonic jets. It is confirmed that nozzles involving turbulent boundary layers are the quietest while nozzles involving a nominally-laminar boundary layer are loud especially on the high-frequency side of the sound pressure level spectrum. The latter boundary layer state involves a Blasius-like mean velocity profile but higher turbulence intensities compared to those in the turbulent state. The higher turbulence in the initial region of the jet shear layer leads to increased high-frequency noise. The results strongly suggest that an anomaly noted with subsonic jet noise databases in the literature is due to a similar effect of differences in the initial boundary layer state.

Rover Low Gain Antenna Qualification for Deep Space Thermal Environments

NASA Technical Reports Server (NTRS)

Ramesham, Rajeshuni; Amaro, Luis R.; Brown, Paula R.; Usiskin, Robert; Prater, Jack L.

2013-01-01

A method to qualify the Rover Low Gain Antenna (RLGA) for use during the Mars Science Laboratory (MSL) mission has been devised. The RLGA antenna must survive all ground operations, plus the nominal 670 Martian sol mission that includes the summer and winter seasons of the Mars thermal environment. This qualification effort was performed to verify that the RLGA design, its bonding, and packaging processes are adequate. The qualification test was designed to demonstrate a survival life of three times more than all expected ground testing, plus a nominal 670 Martian sol missions. Baseline RF tests and a visual inspection were performed on the RLGA hardware before the start of the qualification test. Functional intermittent RF tests were performed during thermal chamber breaks over the course of the complete qualification test. For the return loss measurements, the RLGA antenna was moved to a test area. A vector network analyzer was calibrated over the operational frequency range of the antenna. For the RLGA, a simple return loss measurement was performed. A total of 2,010 (3 670 or 3 times mission thermal cycles) thermal cycles was performed. Visual inspection of the RLGA hardware did not show any anomalies due to the thermal cycling. The return loss measurement results of the RLGA antenna after the PQV (Package Qualification and Verification) test did not show any anomalies. The antenna pattern data taken before and after the PQV test at the uplink and downlink frequencies were unchanged. Therefore, the developed design of RLGA is qualified for a long-duration MSL mission.

Robust crossfeed design for hovering rotorcraft. M.S. Thesis

NASA Technical Reports Server (NTRS)

Catapang, David R.

1993-01-01

Control law design for rotorcraft fly-by-wire systems normally attempts to decouple angular responses using fixed-gain crossfeeds. This approach can lead to poor decoupling over the frequency range of pilot inputs and increase the load on the feedback loops. In order to improve the decoupling performance, dynamic crossfeeds may be adopted. Moreover, because of the large changes that occur in rotorcraft dynamics due to small changes about the nominal design condition, especially for near-hovering flight, the crossfeed design must be 'robust.' A new low-order matching method is presented here to design robost crossfeed compensators for multi-input, multi-output (MIMO) systems. The technique identifies degrees-of-freedom that can be decoupled using crossfeeds, given an anticipated set of parameter variations for the range of flight conditions of concern. Cross-coupling is then reduced for degrees-of-freedom that can use crossfeed compensation by minimizing off-axis response magnitude average and variance. Results are presented for the analysis of pitch, roll, yaw, and heave coupling of the UH-60 Black Hawk helicopter in near-hovering flight. Robust crossfeeds are designed that show significant improvement in decoupling performance and robustness over nominal, single design point, compensators. The design method and results are presented in an easily-used graphical format that lends significant physical insight to the design procedure. This plant pre-compensation technique is an appropriate preliminary step to the design of robust feedback control laws for rotorcraft.

78 FR 9891 - Extension of Nominations for Membership on the Ocean Research Advisory Panel

Federal Register 2010, 2011, 2012, 2013, 2014

2013-02-12

... Leadership Council (NORLC), the governing body of the National Oceanographic Partnership Program (NOPP... experience in the field of ocean science and/or ocean resource management. Nominations should be identified... set of nominees will seek to balance a range of geographic and sector representation and experience...

Indoor Airborne Ultrasonic Wireless Communication Using OFDM Methods.

PubMed

Jiang, Wentao; Wright, William M D

2017-09-01

Concerns still exist over the safety of prolonged exposure to radio frequency (RF) wireless transmissions and there are also potential data security issues due to remote signal interception techniques such as Bluesniping. Airborne ultrasound may be used as an alternative to RF for indoor wireless communication systems for securely transmitting data over short ranges, as signals are difficult to intercept from outside the room. Two types of air-coupled capacitive ultrasonic transducer were used in the implementation of an indoor airborne wireless communication system. One was a commercially available SensComp series 600 ultrasonic transducer with a nominal frequency of 50 kHz, and the other was a prototype transducer with a high- k dielectric layer operating at higher frequencies from 200 to 400 kHz. Binary phase-shift keying (BPSK), quadrature phase-shift keying (QPSK), and quadrature amplitude modulation (QAM)-based orthogonal frequency division multiplexing modulation methods were successfully implemented using multiple orthogonal subchannels. The modulated ultrasonic signal packets were synchronized using a wireless link, and a least-squares channel estimation algorithm was used to compensate the phase and amplitude distortion introduced by the air channel. By sending and receiving the ultrasonic signals using the SensComp transducers, the achieved maximum system data rate was up to 180 kb/s using 16-QAM with ultrasonic channels from 55 to 99 kHz, over a line-of-sight transmission distance of 6 m with no detectable errors. The transmission range could be extended to 9 and 11 m using QPSK and BPSK modulation schemes, respectively. The achieved data rates for the QPSK and BPSK schemes were 90 and 45 kb/s using the same bandwidth. For the high- k ultrasonic transducers, a maximum data rate up to 800 kb/s with no measurable errors was achieved up to a range of 0.7 m. The attainable transmission ranges were increased to 1.1 and 1.2 m with data rates of 400 and 200 kb/s using QPSK and BPSK, respectively.

Rise time and response measurements on a LiSOCl2 cell

NASA Technical Reports Server (NTRS)

Bastien, Caroline; Lecomte, Eric J.

1992-01-01

Dynamic impedance tests were performed on a 180 Ah LiSOCl2 cell in the frame of a short term work contract awarded by Aerospatiale as part of the Hermes Space Plane development work. These tests consisted of rise time and response measurements. The rise time test was performed to show the ability to deliver 4 KW, in the nominal voltage range (75-115 V), within less than 100 microseconds, and after a period at rest of 13 days. The response measurements test consisted of step response and frequency response tests. The frequency response test was performed to characterize the response of the LiSOCl2 cell to a positive or negative load step of 10 A starting from various currents. The test was performed for various depths of discharge and various temperatures. The test results were used to build a mathematical, electrical model of the LiSOCl2 cell which are also presented. The test description, test results, electrical modelization description, and conclusions are presented.

A lightweight vibro-acoustic metamaterial demonstrator: Numerical and experimental investigation

NASA Astrophysics Data System (ADS)

Claeys, C.; Deckers, E.; Pluymers, B.; Desmet, W.

2016-03-01

In recent years metamaterials gained a lot of attention due to their superior noise and vibration insulation properties, be it at least in some targeted and tuneable frequency ranges, referred to as stopbands. These are frequency zones for which free wave propagation is prevented throughout the metamaterial, resulting in frequency zones of pronounced wave attenuation. Metamaterials are achieved due to addition of an, often periodic, grid of resonant structures to a host material or structure. The interaction between resonant inclusions and host structure can lead to a performance which is superior to the ones of any of the constituent materials. A key element in this concept is that waves can be affected by incorporating structural resonant elements of sub-wavelength sizes, i.e. features that are actually smaller than the wavelength of the waves to be affected. This paves the way towards compact and light vibro-acoustic solutions in the lower frequency ranges. This paper discusses the numerical design and experimental validation of acoustic insulation based on the concept of metamaterials: a hollow core periodic sandwich structure with added local resonant structures. In order to investigate the sensitivity to specific parameters in the metamaterial design and the robustness of the design, a set of variations on the nominal design are investigated. The stop bands are numerically predicted through unit cell modelling after which a full vibro-acoustic finite element model is applied to predict the insertion loss of the demonstrator. The results of these analyses are compared with measurements; both indicate that this metamaterials concept can be applied to combine light weight, compact volume and good acoustic behaviour.

Acoustic Radiation From a Mach 14 Turbulent Boundary Layer

NASA Technical Reports Server (NTRS)

Zhang, Chao; Duan, Lian; Choudhari, Meelan M.

2016-01-01

Direct numerical simulations (DNS) are used to examine the turbulence statistics and the radiation field generated by a high-speed turbulent boundary layer with a nominal freestream Mach number of 14 and wall temperature of 0:18 times the recovery temperature. The flow conditions fall within the range of nozzle exit conditions of the Arnold Engineering Development Center (AEDC) Hypervelocity Tunnel No. 9 facility. The streamwise domain size is approximately 200 times the boundary-layer thickness at the inlet, with a useful range of Reynolds number corresponding to Re 450 ?? 650. Consistent with previous studies of turbulent boundary layer at high Mach numbers, the weak compressibility hypothesis for turbulent boundary layers remains applicable under this flow condition and the computational results confirm the validity of both the van Driest transformation and Morkovin's scaling. The Reynolds analogy is valid at the surface; the RMS of fluctuations in the surface pressure, wall shear stress, and heat flux is 24%, 53%, and 67% of the surface mean, respectively. The magnitude and dominant frequency of pressure fluctuations are found to vary dramatically within the inner layer (z/delta 0.< or approx. 0.08 or z+ < or approx. 50). The peak of the pre-multiplied frequency spectrum of the pressure fluctuation is f(delta)/U(sub infinity) approx. 2.1 at the surface and shifts to a lower frequency of f(delta)/U(sub infinity) approx. 0.7 in the free stream where the pressure signal is predominantly acoustic. The dominant frequency of the pressure spectrum shows a significant dependence on the freestream Mach number both at the wall and in the free stream.

78 FR 60892 - Outer Continental Shelf (OCS), Alaska OCS Region, Chukchi Sea Planning Area, Proposed Oil and Gas...

Federal Register 2010, 2011, 2012, 2013, 2014

2013-10-02

..., concerning the importance of these areas or associated activities. 6. Submissions of Nominations, Requests... range of interest classifications and anticipated activity regarding the nominated area(s). Interested... on the importance of Hanna Shoal and Herald Shoal. While already excluded from the Program Area...

Artifacts Of Spectral Analysis Of Instrument Readings

NASA Technical Reports Server (NTRS)

Wise, James H.

1995-01-01

Report presents experimental and theoretical study of some of artifacts introduced by processing outputs of two nominally identical low-frequency-reading instruments; high-sensitivity servo-accelerometers mounted together and operating, in conjunction with signal-conditioning circuits, as seismometers. Processing involved analog-to-digital conversion with anti-aliasing filtering, followed by digital processing including frequency weighting and computation of different measures of power spectral density (PSD).

76 FR 37813 - Agency Information Collection Activities: Submission for OMB Review; Comment Request

Federal Register 2010, 2011, 2012, 2013, 2014

2011-06-28

... compared with the burden estimates OMB approved on December 22, 2010, for OMB 0938-1087. There is a nominal...: 0938- 1087); Frequency: Occasionally; Affected Public: Private Sector: Business or other for-profits...

High-frequency viscoelastic shear properties of vocal fold tissues: implications for vocal fold tissue engineering.

PubMed

Teller, Sean S; Farran, Alexandra J E; Xiao, Longxi; Jiao, Tong; Duncan, Randall L; Clifton, Rodney J; Jia, Xinqiao

2012-10-01

The biomechanical function of the vocal folds (VFs) depends on their viscoelastic properties. Many conditions can lead to VF scarring that compromises voice function and quality. To identify candidate replacement materials, the structure, composition, and mechanical properties of native tissues need to be understood at phonation frequencies. Previously, the authors developed the torsional wave experiment (TWE), a stress-wave-based experiment to determine the linear viscoelastic shear properties of small, soft samples. Here, the viscoelastic properties of porcine and human VFs were measured over a frequency range of 10-200 Hz. The TWE utilizes resonance phenomena to determine viscoelastic properties; therefore, the specimen test frequency is determined by the sample size and material properties. Viscoelastic moduli are reported at resonance frequencies. Structure and composition of the tissues were determined by histology and immunochemistry. Porcine data from the TWE are separated into two groups: a young group, consisting of fetal and newborn pigs, and an adult group, consisting of 6-9-month olds and 2+-year olds. Adult tissues had an average storage modulus of 2309±1394 Pa and a loss tangent of 0.38±0.10 at frequencies of 36-200 Hz. The VFs of young pigs were significantly more compliant, with a storage modulus of 394±142 Pa and a loss tangent of 0.40±0.14 between 14 and 30 Hz. No gender dependence was observed. Histological staining showed that adult porcine tissues had a more organized, layered structure than the fetal tissues, with a thicker epithelium and a more structured lamina propria. Elastin fibers in fetal VF tissues were immature compared to those in adult tissues. Together, these structural changes in the tissues most likely contributed to the change in viscoelastic properties. Adult human VF tissues, recovered postmortem from adult patients with a history of smoking or disease, had an average storage modulus of 756±439 Pa and a loss tangent of 0.42±0.10. Contrary to the results of some other investigators, no significant frequency dependence was observed. This lack of observable frequency dependence may be due to the modest frequency range of the experiments and the wide range of stiffnesses observed within nominally similar sample types.

High-Frequency Viscoelastic Shear Properties of Vocal Fold Tissues: Implications for Vocal Fold Tissue Engineering

PubMed Central

Teller, Sean S.; Farran, Alexandra J.E.; Xiao, Longxi; Jiao, Tong; Duncan, Randall L.

2012-01-01

The biomechanical function of the vocal folds (VFs) depends on their viscoelastic properties. Many conditions can lead to VF scarring that compromises voice function and quality. To identify candidate replacement materials, the structure, composition, and mechanical properties of native tissues need to be understood at phonation frequencies. Previously, the authors developed the torsional wave experiment (TWE), a stress-wave-based experiment to determine the linear viscoelastic shear properties of small, soft samples. Here, the viscoelastic properties of porcine and human VFs were measured over a frequency range of 10–200 Hz. The TWE utilizes resonance phenomena to determine viscoelastic properties; therefore, the specimen test frequency is determined by the sample size and material properties. Viscoelastic moduli are reported at resonance frequencies. Structure and composition of the tissues were determined by histology and immunochemistry. Porcine data from the TWE are separated into two groups: a young group, consisting of fetal and newborn pigs, and an adult group, consisting of 6–9-month olds and 2+-year olds. Adult tissues had an average storage modulus of 2309±1394 Pa and a loss tangent of 0.38±0.10 at frequencies of 36–200 Hz. The VFs of young pigs were significantly more compliant, with a storage modulus of 394±142 Pa and a loss tangent of 0.40±0.14 between 14 and 30 Hz. No gender dependence was observed. Histological staining showed that adult porcine tissues had a more organized, layered structure than the fetal tissues, with a thicker epithelium and a more structured lamina propria. Elastin fibers in fetal VF tissues were immature compared to those in adult tissues. Together, these structural changes in the tissues most likely contributed to the change in viscoelastic properties. Adult human VF tissues, recovered postmortem from adult patients with a history of smoking or disease, had an average storage modulus of 756±439 Pa and a loss tangent of 0.42±0.10. Contrary to the results of some other investigators, no significant frequency dependence was observed. This lack of observable frequency dependence may be due to the modest frequency range of the experiments and the wide range of stiffnesses observed within nominally similar sample types. PMID:22741523

Measurement of Turbulent Pressure and Temperature Fluctuations in a Gas Turbine Combustor

NASA Technical Reports Server (NTRS)

Passaro, Andrea; LaGraff, John E.; Oldfield, Martin L. G.; Biagioni, Leonardo; Moss, Roger W.; Battelle, Ryan T.; Povinelli, Louis A. (Technical Monitor)

2003-01-01

The present research concerns the development of high-frequency pressure and temperature probes and related instrumentation capable of performing spectral characterization of unsteady pressure and temperature fluctuations over the 0.05 20 kHz range, at the exit of a gas turbine combustor operating at conditions close to nominal ones for large power generation turbomachinery. The probes used a transient technique pioneered at Oxford University; in order to withstand exposure to the harsh environment the probes were fitted on a rapid injection and cooling system jointly developed by Centrospazio CPR and Syracuse University. The experimental runs were performed on a large industrial test rig being operated by ENEL Produzione. The achieved results clearly show the satisfactory performance provided by this diagnostic tool, even though the poor location of the injection port prevented the tests from yielding more insight of the core flow turbulence characteristics. The pressure and temperature probes survived several dozen injections in the combustor hot jet, while consistently providing the intended high frequency performance. The apparatus was kept connected to the combustor during long duration firings, operating as an unobtrusive, self contained, piggy-back experiment: high frequency flow samplings were remotely recorded at selected moments corresponding to different combustor operating conditions.

Performance characteristics of three-phase induction motors

NASA Technical Reports Server (NTRS)

Wood, M. E.

1977-01-01

An investigation into the characteristics of three phase, 400 Hz, induction motors of the general type used on aircraft and spacecraft is summarized. Results of laboratory tests are presented and compared with results from a computer program. Representative motors were both tested and simulated under nominal conditions as well as off nominal conditions of temperature, frequency, voltage magnitude, and voltage balance. Good correlation was achieved between simulated and laboratory results. The primary purpose of the program was to verify the simulation accuracy of the computer program, which in turn will be used as an analytical tool to support the shuttle orbiter.

78 FR 57411 - Second Call for Nominations for the Rio Grande Natural Area Commission, CO

Federal Register 2010, 2011, 2012, 2013, 2014

2013-09-18

... Nominations for the Rio Grande Natural Area Commission, CO AGENCY: Bureau of Land Management, Interior. ACTION... Specialist, BLM Front Range District Office, 3028 East Main St., Ca[ntilde]on City, CO 81212. FOR FURTHER... themselves or others. The BLM will evaluate nominees based on their education, training, experience and...

ELECTRIC AND MAGNETIC FIELDS <100 KHZ IN ELECTRIC AND GASOLINE-POWERED VEHICLES.

PubMed

Tell, Richard A; Kavet, Robert

2016-12-01

Measurements were conducted to investigate electric and magnetic fields (EMFs) from 120 Hz to 10 kHz and 1.2 to 100 kHz in 9 electric or hybrid vehicles and 4 gasoline vehicles, all while being driven. The range of fields in the electric vehicles enclosed the range observed in the gasoline vehicles. Mean magnetic fields ranged from nominally 0.6 to 3.5 µT for electric/hybrids depending on the measurement band compared with nominally 0.4 to 0.6 µT for gasoline vehicles. Mean values of electric fields ranged from nominally 2 to 3 V m -1 for electric/hybrid vehicles depending on the band, compared with 0.9 to 3 V m -1 for gasoline vehicles. In all cases, the fields were well within published exposure limits for the general population. The measurements were performed with Narda model EHP-50C/EHP-50D EMF analysers that revealed the presence of spurious signals in the EHP-50C unit, which were resolved with the EHP-50D model. © The Author 2016. Published by Oxford University Press. All rights reserved. For Permissions, please email: journals.permissions@oup.com.

Fatigue life prediction in bending from axial fatigue information

NASA Technical Reports Server (NTRS)

Manson, S. S.; Muralidharan, U.

1982-01-01

Bending fatigue in the low cyclic life range differs from axial fatigue due to the plastic flow which alters the linear stress-strain relation normally used to determine the nominal stresses. An approach is presented to take into account the plastic flow in calculating nominal bending stress (S sub bending) based on true surface stress. These functions are derived in closed form for rectangular and circular cross sections. The nominal bending stress and the axial fatigue stress are plotted as a function of life (N sub S) and these curves are shown for several materials of engineering interest.

VizieR Online Data Catalog: Planck Catalog of Compact Sources Release 1 (Planck, 2013)

NASA Astrophysics Data System (ADS)

Planck Collaboration

2013-03-01

Planck is a European Space Agency (ESA) mission, with significant contributions from the U.S. National Aeronautics and Space Agency (NASA). It is the third generation of space-based cosmic microwave background experiments, after the Cosmic Background Explorer (COBE) and the Wilkinson Microwave Anisotropy Probe (WMAP). Planck was launched on 14 May 2009 on an Ariane 5 rocket from Kourou, French Guiana. Following a cruise to the Earth-Sun L2 Lagrange point, cooling and in orbit checkout, Planck initiated the First Light Survey on 13 August 2009. Since then, Planck has been continuously measuring the intensity of the sky over a range of frequencies from 30 to 857GHz (wavelengths of 1cm to 350μm) with spatial resolutions ranging from about 33' to 5' respectively. The Low Frequency Instrument (LFI) on Planck provides temperature and polarization information using radiometers which operate between 30 and 70GHz. The High Frequency Instrument (HFI) uses pairs of polarization-sensitive bolometers at each of four frequencies between 100 and 353GHz but does not measure polarization information in the two upper HFI bands at 545 and 857GHz. The lowest frequencies overlap with WMAP, and the highest frequencies extend far into the submillimeter in order to improve separation between Galactic foregrounds and the cosmic microwave background (CMB). By extending to wavelengths longer than those at which the Infrared Astronomical Satellite (IRAS) operated, Planck is providing an unprecedented window into dust emission at far-infrared and submillimeter wavelengths. The PCCS (Planck Catalog of Compact Sources) is the list of sources detected in the first 15 months of Planck "nominal" mission. It consists of nine single-frequency catalogues of compact sources, both Galactic and extragalactic, detected over the entire sky. The PCCS covers the frequency range 30-857 GHz with higher sensitivity (it is 90% complete at 180mJy in the best channel) and better angular resolution than previous all-sky surveys in the microwave band. By construction its reliability is >80% and more than 65% of the sources have been detected at least in two contiguous Planck channels. Many of the Planck PCCS sources can be associated with stars with dust shells, stellar cores, radio galaxies, blazars, infrared luminous galaxies and Galactic interstellar medium features. (12 data files).

SOI MESFETs on high-resistivity, trap-rich substrates

NASA Astrophysics Data System (ADS)

Mehr, Payam; Zhang, Xiong; Lepkowski, William; Li, Chaojiang; Thornton, Trevor J.

2018-04-01

The DC and RF characteristics of metal-semiconductor field-effect-transistors (MESFETs) on conventional CMOS silicon-on-insulator (SOI) substrates are compared to nominally identical devices on high-resistivity, trap-rich SOI substrates. While the DC transfer characteristics are statistically identical on either substrate, the maximum available gain at GHz frequencies is enhanced by ∼2 dB when using the trap-rich substrates, with maximum operating frequencies, fmax, that are approximately 5-10% higher. The increased fmax is explained by the reduced substrate conduction at GHz frequencies using a lumped-element, small-signal model.

Design of an Autonomous Underwater Vehicle (AUV) Charging System for Underway, Underwater Recharging

DTIC Science & Technology

2014-05-09

again increase the size of the system. A comparison between switching frequency and efficiency for a nominal DC/DC converter was done in an EE ...Choosing the Optimum Switching Frequency of your DC / DC Converter,” EE Times, pp. 1–7, 2006. [19] ON Semiconductors, “Effects of High Switching Frequency...3.1W OUTPUT FILTER CAPACITOR EEE -FC1H101P 100uF ELECTROLYTIC 50V OUTPUT FILTER CAPACITOR C5750X7S2A106M230KB 10uF CERAMIC 100V

47 CFR 15.31 - Measurement standards.

Code of Federal Regulations, 2010 CFR

2010-10-01

... the installation site, such as perimeter protection systems, carrier current systems, and systems... variation of the input power or the radiated signal level of the fundamental frequency component of the... nominal rated supply voltage. For battery operated equipment, the equipment tests shall be performed using...

Active Control of High-Speed Free Jets Using High-Frequency Excitation

NASA Astrophysics Data System (ADS)

Upadhyay, Puja

Control of aerodynamic noise generated by high-performance jet engines continues to remain a serious problem for the aviation community. Intense low frequency noise produced by large-scale coherent structures is known to dominate acoustic radiation in the aft angles. A tremendous amount of research effort has been dedicated towards the investigation of many passive and active flow control strategies to attenuate jet noise, while keeping performance penalties to a minimum. Unsteady excitation, an active control technique, seeks to modify acoustic sources in the jet by leveraging the naturally-occurring flow instabilities in the shear layer. While excitation at a lower range of frequencies that scale with the dynamics of large-scale structures, has been attempted by a number of studies, effects at higher excitation frequencies remain severely unexplored. One of the major limitations stems from the lack of appropriate flow control devices that have sufficient dynamic response and/or control authority to be useful in turbulent flows, especially at higher speeds. To this end, the current study seeks to fulfill two main objectives. First, the design and characterization of two high-frequency fluidic actuators (25 and 60 kHz) are undertaken, where the target frequencies are guided by the dynamics of high-speed free jets. Second, the influence of high-frequency forcing on the aeroacoustics of high-speed jets is explored in some detail by implementing the nominally 25 kHz actuator on a Mach 0.9 (Re D = 5 x 105) free jet flow field. Subsequently, these findings are directly compared to the results of steady microjet injection experiments performed in the same rig and to prior jet noise control studies, where available. Finally, limited acoustic measurements were also performed by implementing the nominally 25 kHz actuators on jets at higher Mach numbers, including shock containing jets, and elevated temperatures. Using lumped element modeling as an initial guide, the current work expands on the previous development of low-frequency (2-8 kHz) Resonance Enhanced Micro-actuators (REM) to design actuators that are capable of producing high amplitude pulses at much higher frequencies. Extensive benchtop characterization, using acoustic measurements as well as optical diagnostics using a high resolution micro-schlieren setup, is employed to characterize the flow properties and dynamic response of these actuators. The actuators produced high-amplitude output a range of frequencies, 20.3-27.8 kHz and 54.8-78.2 kHz, respectively. In addition to providing information on the actuator flow physics and performances at various operating conditions, the benchtop study serves to develop relatively easy-to-integrate, high-frequency actuators for active control of high-speed jets for noise reduction. Following actuator characterization studies, the nominally 25 kHz ( StDF ≈ 2.2) actuators are implemented on a Mach 0.9 free jet flow field. Eight actuators are azimuthally distributed at the nozzle exit to excite the initial shear layer at frequencies that are approximately an order of magnitude higher compared to the jet preferred frequency, StP ≈ 0.2-0.3. The influence of control on the mean and turbulent characteristics of the jet, especially the developing shear layer, is examined in great detail using planar and stereoscopic Particle Image Velocimetry (PIV). Examination of cross-stream velocity profiles revealed that actuation leads to strong, spatially coherent streamwise vortex pairs which in turn significantly modify the mean flow field, resulting in a prominently undulated shear layer. These vortices grow as they convect downstream, enhancing local entrainment and significantly thickening the initial shear layer. Azimuthal inhomogeneity introduced in the jet shear layer is also evident in the simultaneous redistribution and reduction of peak turbulent fluctuations in the cross-plane near the nozzle exit. Further downstream, control results in a global suppression of turbulence intensities for all axial locations, also evidenced by a longer potential core and overall reduced jet spreading. The resulting impact on the noise signature is estimated via far-field acoustic measurements. Noise reduction was observed at low to moderate frequencies for all observation angles. Direct comparison of these results with that of steady microjet injection revealed some notable differences in the initial development of streamwise vorticity and the redistribution of peak turbulence in the azimuthal direction. However, despite significant differences in the near nozzle aerodynamics, the downstream evolution of the jet appeared to approach near similar conditions with both high-frequency and steady microjet injection. Moreover, the impact on far-field noise was also comparable between the two injection methods as well as with others reported in the literature. Finally, for jets at higher Mach numbers and elevated temperatures, the effect of control was observed to vary with jet conditions. While the impact of the two control mechanisms were fairly comparable on non-shock containing jets, high-frequency forcing was observed to produce significantly larger reductions in screech and broadband shock-associated noise (BBSN) at select under-expanded jet conditions. The observed variations in control effects at different jet conditions call for further investigation.

Enhanced ID Pit Sizing Using Multivariate Regression Algorithm

NASA Astrophysics Data System (ADS)

Krzywosz, Kenji

2007-03-01

EPRI is funding a program to enhance and improve the reliability of inside diameter (ID) pit sizing for balance-of plant heat exchangers, such as condensers and component cooling water heat exchangers. More traditional approaches to ID pit sizing involve the use of frequency-specific amplitude or phase angles. The enhanced multivariate regression algorithm for ID pit depth sizing incorporates three simultaneous input parameters of frequency, amplitude, and phase angle. A set of calibration data sets consisting of machined pits of various rounded and elongated shapes and depths was acquired in the frequency range of 100 kHz to 1 MHz for stainless steel tubing having nominal wall thickness of 0.028 inch. To add noise to the acquired data set, each test sample was rotated and test data acquired at 3, 6, 9, and 12 o'clock positions. The ID pit depths were estimated using a second order and fourth order regression functions by relying on normalized amplitude and phase angle information from multiple frequencies. Due to unique damage morphology associated with the microbiologically-influenced ID pits, it was necessary to modify the elongated calibration standard-based algorithms by relying on the algorithm developed solely from the destructive sectioning results. This paper presents the use of transformed multivariate regression algorithm to estimate ID pit depths and compare the results with the traditional univariate phase angle analysis. Both estimates were then compared with the destructive sectioning results.

Passive control of discrete-frequency tones generated by coupled detuned cascades

NASA Astrophysics Data System (ADS)

Sawyer, S.; Fleeter, S.

2003-07-01

Discrete-frequency tones generated by rotor-stator interactions are of particular concern in the design of fans and compressors. Classical theory considers an isolated flat-plate cascade of identical uniformly spaced airfoils. The current analysis extends this tuned isolated cascade theory to consider coupled aerodynamically detuned cascades where aerodynamic detuning is accomplished by changing the chord of alternate rotor blades and stator vanes. In a coupled cascade analysis, the configuration of the rotor influences the downstream acoustic response of the stator, and the stator configuration influences the upstream acoustic response of the rotor. This coupled detuned cascade unsteady aerodynamic model is first applied to a baseline tuned stage. This baseline stage is then aerodynamically detuned by replacing alternate rotor blades and stator vanes with decreased chord airfoils. The nominal aerodynamically detuned stage configuration is then optimized, with the stage acoustic response decreased 13 dB upstream and 1 dB downstream at the design operating condition. A reduction in the acoustic response of the optimized aerodynamically detuned stage is then demonstrated over a range of operating conditions.

Experimental shear strength of unchecked solid-sawn Douglas-fir

Treesearch

D. R. Rammer; L. A. Soltis; P. K. Lebow

This report presents experimental results of modulus of rupture and shear strength tests on unsplit, green, sawn Douglas-fir lumber. Five different size-matched specimens, ranging from nominal 2-by 4-in (standard 38- by 89-mm) to nominal 4- by 14-in (standard 95-by 343-mm), were tested in third-point bending and five-point beam shear. A total of 120 bending and 160...

Millimeter-Wave Gyroklystron Amplifier Experiment Using a Relativistic Electron Beam

DTIC Science & Technology

1990-03-08

Qint to 400 for the TE1 l1 mode, while assisting in suppressing other competing modes [7]. The length of these slots is three times the nominal cavity...frequency by tranverse compression by means of separate clamps. However, cavity deformation affects both the center frequency and the value 5 of Q...amplifier operation was limited by the excitation of parasitic oscillation of the competing TE1 12 mode, as predicted by theory [7]. Despite this

Systems Modeling for Crew Core Body Temperature Prediction Postlanding

NASA Technical Reports Server (NTRS)

Cross, Cynthia; Ochoa, Dustin

2010-01-01

The Orion Crew Exploration Vehicle, NASA s latest crewed spacecraft project, presents many challenges to its designers including ensuring crew survivability during nominal and off nominal landing conditions. With a nominal water landing planned off the coast of San Clemente, California, off nominal water landings could range from the far North Atlantic Ocean to the middle of the equatorial Pacific Ocean. For all of these conditions, the vehicle must provide sufficient life support resources to ensure that the crew member s core body temperatures are maintained at a safe level prior to crew rescue. This paper will examine the natural environments, environments created inside the cabin and constraints associated with post landing operations that affect the temperature of the crew member. Models of the capsule and the crew members are examined and analysis results are compared to the requirement for safe human exposure. Further, recommendations for updated modeling techniques and operational limits are included.

Plug cluster module demonstration

NASA Technical Reports Server (NTRS)

Rousar, D. C.

1978-01-01

The low pressure, film cooled rocket engine design concept developed during two previous ALRC programs was re-evaluated for application as a module for a plug cluster engine capable of performing space shuttle OTV missions. The nominal engine mixture ratio was 5.5 and the engine life requirements were 1200 thermal cycles and 10 hours total operating life. The program consisted of pretest analysis; engine tests, performed using residual components; and posttest analysis. The pretest analysis indicated that operation of the operation of the film cooled engine at O/F = 5.5 was feasible. During the engine tests, steady state wall temperature and performance measurement were obtained over a range of film cooling flow rates, and the durability of the engine was demonstrated by firing the test engine 1220 times at a nominal performance ranging from 430 - 432 seconds. The performance of the test engine was limited by film coolant sleeve damage which had occurred during previous testing. The post-test analyses indicated that the nominal performance level can be increased to 436 seconds.

Air Traffic Controllers' Control Strategies in the Terminal Area Under Off-Nominal Conditions

NASA Technical Reports Server (NTRS)

Martin, Lynne; Mercer, Joey; Callantine, Todd; Kupfer, Michael; Cabrall, Christopher

2012-01-01

A human-in-the-loop simulation investigated the robustness of a schedule-based terminal-area air traffic management concept, and its supporting controller tools, to off-nominal events - events that led to situations in which runway arrival schedules required adjustments and controllers could no longer use speed control alone to impose the necessary delays. The main research question was exploratory: to assess whether controllers could safely resolve and control the traffic during off-nominal events. A focus was the role of the supervisor - how he managed the schedules, how he assisted the controllers, what strategies he used, and which combinations of tools he used. Observations and questionnaire responses revealed supervisor strategies for resolving events followed a similar pattern: a standard approach specific to each type of event often resolved to a smooth conclusion. However, due to the range of factors influencing the event (e.g., environmental conditions, aircraft density on the schedule, etc.), sometimes the plan required revision and actions had a wide-ranging effect.

DOE Office of Scientific and Technical Information (OSTI.GOV)

Tan, Jin; Zhang, Yingchen; Krad, Ibrahim

Power system frequency needs to be maintained close to its nominal value at all times to avoid machine damage, under-frequency load-shedding and even blackouts. Adequate primary frequency response and secondary frequency response are the primary forces to correct an energy imbalance at the second to minute level. As wind energy becomes a larger portion of the world's energy portfolio, there are greater oppotunities for wind to provide frequency response services. This paper addresses one area of frequency control that has been missing in previous work - the reliabilty impacts and interactions between primary and secondary frequency control. The lack ofmore » a commercially available tools to simulate the interaction of these two responses has limited the energy industry's understanding of when the depletion of primary control reserve will impact the performance of secondary conrol response or vice versa. To investigate this issue, in this paper we develop a multi-area frequency response integration model with combined primary and secondary frequency control capabilities.« less

ExoMars Entry Demonstrator Module Dynamic Stability

NASA Astrophysics Data System (ADS)

Dormieux, Marc; Gulhan, Ali; Berner, Claude

2011-05-01

In the frame of ExoMars DM aerodynamics characterization, pitch damping derivatives determination is required as it drives the parachute deployment conditions. Series of free-flight and free- oscillation tests (captive model) have been conducted with particular attention for data reduction. 6 Degrees- of-Freedom (DoF) analysis tools require the knowledge of local damping derivatives. In general ground tests do not provide them directly but only effective damping derivatives. Free-flight (ballistic range) tests with full oscillations around trim angle have been performed at ISL for 0.5

Detection of the large meteoroid/NEO flux using infrasound: recent detection of the November 21, 1995, Colorado fireball

NASA Astrophysics Data System (ADS)

Revelle, Douglas O.; Whitaker, Rodney W.

1996-10-01

During the early morning of November 21, 1995, a fireball as bright as the full moon entered the atmosphere over southeastern Colorado and initially produced audible sonic boom reports from Texas to Wyoming. The event was detected locally by a security video camera which showed the reflection of the fireball event on the hood of a truck. The camera also recorded tree shadows cast by the light of the fireball. This recording includes the audio signal of a strong double boom as well. Subsequent investigation of the array near Los Alamos, New Mexico operated by the Los Alamos National Laboratory as part of its commitment to the Comprehensive Test Ban Treaty negotiations, showed the presence of an infrasonic signal from the proper direction at about the correct time for this fireball. The Los Alamos array is a four-element infrasonic system in near-continuous operation on the laboratory property. The nominal spacing between the array elements is 212 m. The basic sensor is a Globe Universal Sciences Model 100C microphone whose response is flat from about 0.1 to 300 Hz (which we filter at the high frequency end to be limited to 20 Hz). Each low frequency microphone is connected to a set of twelve porous hoses to reduce wind noise. The characteristics of the observed signal include the onset arrival time of 0939:20 UT (0239:20 MST), with a maximum timing uncertainty of plus or minus 2 minutes, the signal onset time delay from the appearance of the fireball of 21 minutes, 20 seconds, total signal duration of 2 minutes 10 seconds, the source location determined to be toward 31 degrees from true north, the horizontal trace velocity of 429 m/sec, the signal velocity of 0.29 plus or minus 0.03 km/sec, assuming a 375 km horizontal range to the fireball, the dominant signal frequency content of 0.25 to 0.84 Hz (analyzed in the frequency interval from 0.2 to 2.0 Hz), the maximum signal cross-correlation of 0.97 and the maximum signal amplitude of 2.0 plus or minus 0.1 microbars. Also, on the basis of the signal period at maximum amplitude, we estimate a probable source energy for this event of between 10 to 100 tons of TNT (53.0 tons nominal).

The role of the deep space network's frequency and timing system in the detection of gravitational waves

NASA Technical Reports Server (NTRS)

Mankins, J. C.

1982-01-01

A review of the Deep Space Network's (DSN) use of precision Doppler-tracking of deep space vehicles is presented. The review emphasizes operational and configurational aspects and considers: the projected configuration of the DSN's frequency and timing system; the environment within the DSN provided by the precision atomic standards within the frequency and timing system--both current and projected; and the general requirements placed on the DSN and the frequency and timing system for both the baseline and the nominal gravitational wave experiments. A comment is made concerning the current probability that such an experiment will be carried out in the foreseeable future.

75 FR 30841 - Advisory Commission on Childhood Vaccines; Request for Nominations for Voting Members

Federal Register 2010, 2011, 2012, 2013, 2014

2010-06-02

... that result in fewer or no significant adverse reactions; surveying Federal, State, and local programs... childhood vaccines, including the adverse reaction reporting requirements of section 2125(b); advising the... frequency and severity of adverse reactions associated with childhood vaccines; consulting on the...

78 FR 61372 - Advisory Commission of Childhood Vaccines; Request for Nominations for Voting Members

Federal Register 2010, 2011, 2012, 2013, 2014

2013-10-03

... reactions; surveying federal, state, and local programs and activities related to gathering information on injuries associated with the administration of childhood vaccines, including the adverse reaction reporting... using credible data related to the frequency and severity of adverse reactions associated with childhood...

High precision moving magnet chopper for variable operation conditions

NASA Technical Reports Server (NTRS)

Aicher, Winfried; Schmid, Manfred

1994-01-01

In the context of an ESTEC technology contract, a Chopping Mechanism was developed and built with the Far Infrared and Submillimeter Telescope (FIRST) astronomy mission as a reference. The task of the mechanism is to tilt the subreflector of the telescope with an assumed mass of 2.5 kg about one chopping axis at nominal frequencies of up to 5 Hz and chopping angles of up to +/- 11.25 mrad with high efficiency (minimum time for position change). The chopping axis is required to run through the subreflector vertex. After performing a concept trade-off also considering the low operational temperatures in the 130 K range, a design using moving magnet actuators was found to be the favorite one. In addition, a bearing concept using flexible pivots was chosen to meet the high chopping accuracy required. With this approach, a very reliable design could be realized, since the actuators work without any mechanical contact between its moving and fixed parts, and the only bearings used are two flexible pivots supporting the subreflector mounting interface. The mechanism was completely built in titanium in a lightweight and stiff design. The moving magnet actuators were designed to meet the stringent requirements for minimum risetime (time necessary to move from one angular position to a new one) in the 20 msec range. The angular position and the corresponding chopping frequency as well can be arbitrarily selected by the user.

Association study of GABA system genes polymorphisms with amphetamine-induced psychotic disorder in a Han Chinese population.

PubMed

Zhang, Kai; Zhao, Yan; Wang, Qingzhong; Jiang, Haifeng; Du, Jiang; Yu, Shunying; Zhao, Min

2016-05-27

GABA system genes have been implicated in neurotrophy and neurogenesis, which play pivotal roles in an individual's variation in vulnerability to amphetamine addiction or amphetamine-induced psychosis (AIP). We hypothesized that common genetic variants in the GABA system genes may be associated with amphetamine-induced psychotic disorder. In our study, thirty-six single nucleotide polymorphisms (SNPs) within the GABA system genes were genotyped in 400 amphetamine-induced psychotic disorder patients and 400 amphetamine use disorders patients (AUP) (not including those categorized as psychosis) in the Han Chinese population. In this study, 51.88% of the Han Chinese amphetamine-type substance use disorder patients met the criteria of amphetamine-induced psychotic disorder, and 79.5% amphetamine-induced psychotic disorder patients had auditory hallucinations, while 46.5% had delusions of reference. The allele frequency of rs1129647 showed nominal association with AIP in the Han Chinese population (P=0.03). Compared with AUP group patients, T allele frequency of AIP group patients was significantly increased. The adjustment for age and gender factors in the AIP and AUP patients was executed using unconditional logistic regression under five inheritance models. The genotype frequency of rs1129647 showed nominal association with AIP in the log-additive model (P=0.04). The genotype frequency of rs2290733 showed nominal association with AIP in the recessive model (P=0.04). Compared with female AIP patients, male patients were more likely to have the CC genotype of rs17545383 (P=0.04). Moreover, we determined that more male patients carried the T allele of rs2290733 in the AIP group (P=0.004). Unfortunately, the significant differences did not survive Benjamini-Hochberg false discovery rate correction (adjusted P>0.05). No association between the SNPs of the GABA system genes and amphetamine-induced psychotic disorder risk was identified. No haplotype of the GABA system genes affected amphetamine-induced psychotic disorder risk. This report describes the first association study between the GABA system genes and amphetamine-induced psychotic disorder in the Han Chinese population. Our data may provide a reference for future research. Copyright © 2016. Published by Elsevier Ireland Ltd.

Design of a Wideband 900 GHz Balanced Frequency Tripler for Radioastronomy

NASA Technical Reports Server (NTRS)

Tripon-Canseliet, Charlotte; Maestrini, Alain; Mehdi, Imran

2004-01-01

We report on the design of a fix-tuned split-block waveguide balanced frequency tripler working nominally at 900GHz. It uses a GaAs Schottky planar diode pair in a balanced configuration. The circuit will be fabricated with JPL membrane technology in order to minimize dielectric loading. The multiplier is bias-less to dramatically ease the mounting and the operating procedure. At room temperature, the expected output power is 50- 130 (micro)W in the band 800-970 GHz when the tripler is pumped with 4mW. By modifying the waveguide input and output matching circuit, the multiplier can be tuned to operate at lower frequencies.

Effects of eddy currents on selective spectral editing experiments at 3T.

PubMed

Oeltzschner, Georg; Snoussi, Karim; Puts, Nicolaas A; Mikkelsen, Mark; Harris, Ashley D; Pradhan, Subechhya; Tsapkini, Kyrana; Schär, Michael; Barker, Peter B; Edden, Richard A E

2018-03-01

To investigate frequency-offset effects in edited magnetic resonance spectroscopy (MRS) experiments arising from B 0 eddy currents. Macromolecule-suppressed (MM-suppressed) γ-aminobutyric acid (GABA)-edited experiments were performed at 3T. Saturation-offset series of MEGA-PRESS experiments were performed in phantoms, in order to investigate different aspects of the relationship between the effective editing frequencies and eddy currents associated with gradient pulses in the sequence. Difference integrals were quantified for each series, and the offset dependence of the integrals was analyzed to quantify the difference in frequency (Δf) between the actual vs. nominal expected saturation frequency. Saturation-offset N-acetyl-aspartate-phantom experiments show that Δf varied with voxel orientation, ranging from 10.4 Hz (unrotated) to 6.4 Hz (45° rotation about the caudal-cranial axis) and 0.4 Hz (45° rotation about left-right axis), indicating that gradient-related B 0 eddy currents vary with crusher-gradient orientation. Fixing the crusher-gradient coordinate-frame substantially reduced the orientation dependence of Δf (to ∼2 Hz). Water-suppression crusher gradients also introduced a frequency offset, with Δf = 0.6 Hz ("excitation" water suppression), compared to 10.2 Hz (no water suppression). In vivo spectra showed a negative edited "GABA" signal, suggesting Δf on the order of 10 Hz; with fixed crusher-gradient coordinate-frame, the expected positive edited "GABA" signal was observed. Eddy currents associated with pulsed field gradients may have a considerable impact on highly frequency-selective spectral-editing experiments, such as MM-suppressed GABA editing at 3T. Careful selection of crusher gradient orientation may ameliorate these effects. 2 Technical Efficacy: Stage 1 J. Magn. Reson. Imaging 2018;47:673-681. © 2017 International Society for Magnetic Resonance in Medicine.

Redescription of the Indo-Pacific scorpionfish Scorpaenodes guamensis (Quoy & Gaimard 1824) (Scorpaenidae), a senior synonym of seven nominal species.

PubMed

Motomura, Hiroyuki; Causse, Romain; Struthers, Carl D

2016-01-21

The Indo-Pacific scorpionfish, Scorpaenodes guamensis (Quoy & Gaimard 1824), is redescribed on the basis of 137 specimens, including types, from a wide geographic range in the Indo-Pacific. Seven nominal species, Scorpaena rubropunctata Cuvier in Cuvier & Valenciennes 1829, Sebastes minutus Cuvier in Cuvier & Valenciennes 1829, Scorpaena chilioprista Rüppell 1838, Scorpaena polylepis Bleeker 1851, Centropogon echinatus Macleay 1881, Scorpaena erinacea Garman 1903, and Scorpaenopsis quiescens Seale 1906, are regarded here as junior synonyms of S. guamensis. The type status of these nominal species is discussed, and lectotypes of Scorpaena guamensis, Scorpaena rubropunctata, Sebastes minutus, and Scorpaena polylepis are herein designated. Validity of Scorpaenopsis scaber (Ramsay & Ogilby 1886) is also discussed.

Frequency Weighted H2 Control Design for the Glovebox Integrated Microgravity Isolation Technology (g-LIMIT)

NASA Technical Reports Server (NTRS)

Calhoun, Philip C.; Hampton, R. David

2004-01-01

The acceleration environment on the International Space Station (ISS) exceeds the requirements of many microgravity experiments. The Glovebox Integrated Microgravity Isolation Technology (g-LIMIT) has been built by the NASA Marshall Space Flight Center to attenuate the nominal acceleration environment and provide some isolation for microgravity science experiments. The g-LIMIT uses Lorentz (voice-coil) magnetic actuators to isolate a platform, for mounting science payloads, from the nominal acceleration environment. The system utilizes payload-acceleration, relative-position, and relative-orientation measurements in a feedback controller to accomplish the vibration isolation task. The controller provides current commands to six magnetic actuators, producing the required experiment isolation from the ISS acceleration environment. The present work documents the development of a candidate control law to meet the acceleration attenuation requirements for the g-LIMIT experiment platform. The controller design is developed using linear optimal control techniques for frequency-weighted H2 norms. Comparison of performance and robustness to plant uncertainty for this control design approach is included in the discussion. System performance is demonstrated in the presence of plant modeling error.

Evolution of Space Shuttle Range Safety (RS) Ascent Flight Envelope Design

NASA Technical Reports Server (NTRS)

Brewer, Joan D.

2011-01-01

Ascent flight envelopes are trajectories that define the normal operating region of a space vehicle s position from liftoff until the end of powered flight. They fulfill part of the RS data requirements imposed by the Air Force s 45th Space Wing (45SW) on space vehicles launching from the Eastern Range (ER) in Florida. The 45SW is chartered to protect the public by minimizing risks associated with the inherent hazards of launching a vehicle into space. NASA s Space Shuttle program has launched 130+ manned missions over a 30 year period from the ER. Ascent envelopes were delivered for each of those missions. The 45SW envelope requirements have remained largely unchanged during this time. However, the methodology and design processes used to generate the envelopes have evolved over the years to support mission changes, maintain high data quality, and reduce costs. The evolution of the Shuttle envelope design has yielded lessons learned that can be applied to future endevours. There have been numerous Shuttle ascent design enhancements over the years that have caused the envelope methodology to evolve. One of these Shuttle improvements was the introduction of onboard flight software changes implemented to improve launch probability. This change impacted the preflight nominal ascent trajectory, which is a key element in the RS envelope design. While the early Shuttle nominal trajectories were designed preflight using a representative monthly mean wind, the new software changes involved designing a nominal ascent trajectory on launch day using real-time winds. Because the actual nominal trajectory position was not known until launch day, the envelope analysis had to be customized to account for this nominal trajectory variation in addition to the other envelope components.

Aqueous infrared carboxylate absorbances: Aliphatic di-acids

USGS Publications Warehouse

Cabaniss, S.E.; Leenheer, J.A.; McVey, I.F.

1998-01-01

Aqueous attenuated total reflectance Fourier transform infrared (ATR-FTIR) spectra of 18 aliphatic di-carboxylic acids are reported as a function of pH. The spectra show isosbestic points and intensity changes which indicate that Beer's law is obeyed, and peak frequencies lie within previously reported ranges for aqueous carboxylates and pure carboxylic acids. Intensity sharing from the symmetric carboxylate stretch is evident in many cases, so that bands which are nominally due to alkyl groups show increased intensity at higher pH. The asymmetric stretch of the HA- species is linearly related to the microscopic acidity constant of the H2A species, with ??pK 2 intervening atoms). The results suggest that aqueous ATR-FTIR may be able to estimate 'intrinsic' pKa values of carboxylic acids, in addition to providing quantitative estimates of ionization. ?? 1998 Elsevier Science B.V. All rights reserved.

A Comparative Study of Power Supply Architectures In Wireless Electric Vehicle Charging Systems

NASA Astrophysics Data System (ADS)

Esteban, Bryan

Wireless inductive power transfer is a transformational and disruptive technology that enables the reliable and efficient transfer of electrical power over large air gaps for a host of unique applications. One such application that is now gaining much momentum worldwide is the wireless charging of electric vehicles (EVs). This thesis examines two of the primary power supply topologies being predominantly used for EV charging, namely the SLC and the LCL resonant full bridge inverter topologies. The study of both of these topologies is presented in the context of designing a 3 kW, primary side controlled, wireless EV charger with nominal operating parameters of 30 kHz centre frequency and range of coupling in the neighborhood of .18-.26. A comparison of both topologies is made in terms of their complexity, cost, efficiency, and power quality. The aim of the study is to determine which topology is better for wireless EV charging.

Real-time economic nonlinear model predictive control for wind turbine control

NASA Astrophysics Data System (ADS)

Gros, Sebastien; Schild, Axel

2017-12-01

Nonlinear model predictive control (NMPC) is a strong candidate to handle the control challenges emerging in the modern wind energy industry. Recent research suggested that wind turbine (WT) control based on economic NMPC (ENMPC) can improve the closed-loop performance and simplify the task of controller design when compared to a classical NMPC approach. This paper establishes a formal relationship between the ENMPC controller and the classic NMPC approach, and compares empirically their closed-loop nominal behaviour and performance. The robustness of the performance is assessed for an inaccurate modelling of the tower fore-aft main frequency. Additionally, though a perfect wind preview is assumed here, the effect of having a limited horizon of preview of the wind speed via the LIght Detection And Ranging (LIDAR) sensor is investigated. Finally, this paper provides new algorithmic solutions for deploying ENMPC for WT control, and report improved computational times.

Final NASA Panel Recommendations for Definition of Acceptable Risk of Injury Due to Spaceflight Dynamic Events

NASA Technical Reports Server (NTRS)

Somers, Jeffrey T.; Newby, Nate; Wells, Jessica

2015-01-01

A panel of experts was convened in 2010 to help define acceptable injury risk levels for space vehicle launches, landings, and abort scenarios. Classifications of spaceflight-relevant injuries were defined using four categories ranging from minor to severe injury. Limits for each injury category were agreed to, dependent on the expected number of crew exposures in a given vehicle and on whether the flight was considered nominal or off-nominal. Somers et al. captured the findings of this summit in a NASA technical memorandum. This panel was recently re-convened (December 1, 2014) to determine whether the previous recommended injury limits were applicable to newly-designed commercial space flight vehicles. In particular, previous limits were based in part on the number of crew exposures per vehicle and also were sensitive to a definition of nominal and off-nominal vehicle performance. Reconsideration of these aspects led to a new consensus on a definition of injury risk.

Simulations of the failure scenarios of the crab cavities for the nominal scheme of the LHC

NASA Astrophysics Data System (ADS)

Yee, B.; Calaga, R.; Zimmermann, F.; Lopez, R.

2012-02-01

The Crab Cavity (CC) represents a possible solution to the problem of the reduction in luminosity due to the impact angle of two colliding beams. The CC is a Radio Frequency (RF) superconducting cavity which applies a transversal kick into a bunch of particles producing a rotation in order to have a head-on collision to improve the luminosity. For this reason people at the Beams Department-Accelerators & Beams Physics of CERN (BE-ABP) have studied the implementation of the CC scheme at the LHC. It is essential to study the failure scenarios and the damage that can be produced to the lattice devices. We have performed simulations of these failures for the nominal scheme.

Optimal strategy for polarization modulation in the LSPE-SWIPE experiment

NASA Astrophysics Data System (ADS)

Buzzelli, A.; de Bernardis, P.; Masi, S.; Vittorio, N.; de Gasperis, G.

2018-01-01

Context. Cosmic microwave background (CMB) B-mode experiments are required to control systematic effects with an unprecedented level of accuracy. Polarization modulation by a half wave plate (HWP) is a powerful technique able to mitigate a large number of the instrumental systematics. Aims: Our goal is to optimize the polarization modulation strategy of the upcoming LSPE-SWIPE balloon-borne experiment, devoted to the accurate measurement of CMB polarization at large angular scales. Methods: We departed from the nominal LSPE-SWIPE modulation strategy (HWP stepped every 60 s with a telescope scanning at around 12 deg/s) and performed a thorough investigation of a wide range of possible HWP schemes (either in stepped or continuously spinning mode and at different azimuth telescope scan-speeds) in the frequency, map and angular power spectrum domain. In addition, we probed the effect of high-pass and band-pass filters of the data stream and explored the HWP response in the minimal case of one detector for one operation day (critical for the single-detector calibration process). We finally tested the modulation performance against typical HWP-induced systematics. Results: Our analysis shows that some stepped HWP schemes, either slowly rotating or combined with slow telescope modulations, represent poor choices. Moreover, our results point out that the nominal configuration may not be the most convenient choice. While a large class of spinning designs provides comparable results in terms of pixel angle coverage, map-making residuals and BB power spectrum standard deviations with respect to the nominal strategy, we find that some specific configurations (e.g., a rapidly spinning HWP with a slow gondola modulation) allow a more efficient polarization recovery in more general real-case situations. Conclusions: Although our simulations are specific to the LSPE-SWIPE mission, the general outcomes of our analysis can be easily generalized to other CMB polarization experiments.

Time-accurate unsteady flow simulations supporting the SRM T+68-second pressure spike anomaly investigation (STS-54B)

NASA Astrophysics Data System (ADS)

Dougherty, N. S.; Burnette, D. W.; Holt, J. B.; Matienzo, Jose

1993-07-01

Time-accurate unsteady flow simulations are being performed supporting the SRM T+68sec pressure 'spike' anomaly investigation. The anomaly occurred in the RH SRM during the STS-54 flight (STS-54B) but not in the LH SRM (STS-54A) causing a momentary thrust mismatch approaching the allowable limit at that time into the flight. Full-motor internal flow simulations using the USA-2D axisymmetric code are in progress for the nominal propellant burn-back geometry and flow conditions at T+68-sec--Pc = 630 psi, gamma = 1.1381, T(sub c) = 6200 R, perfect gas without aluminum particulate. In a cooperative effort with other investigation team members, CFD-derived pressure loading on the NBR and castable inhibitors was used iteratively to obtain nominal deformed geometry of each inhibitor, and the deformed (bent back) inhibitor geometry was entered into this model. Deformed geometry was computed using structural finite-element models. A solution for the unsteady flow has been obtained for the nominal flow conditions (existing prior to the occurrence of the anomaly) showing sustained standing pressure oscillations at nominally 14.5 Hz in the motor IL acoustic mode that flight and static test data confirm to be normally present at this time. Average mass flow discharged from the nozzle was confirmed to be the nominal expected (9550 lbm/sec). The local inlet boundary condition is being perturbed at the location of the presumed reconstructed anomaly as identified by interior ballistics performance specialist team members. A time variation in local mass flow is used to simulate sudden increase in burning area due to localized propellant grain cracks. The solution will proceed to develop a pressure rise (proportional to total mass flow rate change squared). The volume-filling time constant (equivalent to 0.5 Hz) comes into play in shaping the rise rate of the developing pressure 'spike' as it propagates at the speed of sound in both directions to the motor head end and nozzle. The objectives of the present analysis are to: (1) capture the dynamic responses of the motor combustion gas flow to correlate with available low-frequency (less than 12.5 sample/sec) data and (2) observe the high-frequency (up to 50 Hz) characteristics of the response to determine any potentials for dynamic coupling.

Smart CMOS sensor for wideband laser threat detection

NASA Astrophysics Data System (ADS)

Schwarze, Craig R.; Sonkusale, Sameer

2015-09-01

The proliferation of lasers has led to their widespread use in applications ranging from short range standoff chemical detection to long range Lidar sensing and target designation operating across the UV to LWIR spectrum. Recent advances in high energy lasers have renewed the development of laser weapons systems. The ability to measure and assess laser source information is important to both identify a potential threat as well as determine safety and nominal hazard zone (NHZ). Laser detection sensors are required that provide high dynamic range, wide spectral coverage, pulsed and continuous wave detection, and large field of view. OPTRA, Inc. and Tufts have developed a custom ROIC smart pixel imaging sensor architecture and wavelength encoding optics for measurement of source wavelength, pulse length, pulse repetition frequency (PRF), irradiance, and angle of arrival. The smart architecture provides dual linear and logarithmic operating modes to provide 8+ orders of signal dynamic range and nanosecond pulse measurement capability that can be hybridized with the appropriate detector array to provide UV through LWIR laser sensing. Recent advances in sputtering techniques provide the capability for post-processing CMOS dies from the foundry and patterning PbS and PbSe photoconductors directly on the chip to create a single monolithic sensor array architecture for measuring sources operating from 0.26 - 5.0 microns, 1 mW/cm2 - 2 kW/cm2.

Visualization of a variety of possible dosimetric outcomes in radiation therapy using dose-volume histogram bands.

PubMed

Trofimov, Alexei; Unkelbach, Jan; DeLaney, Thomas F; Bortfeld, Thomas

2012-01-01

Dose-volume histograms (DVH) are the most common tool used in the appraisal of the quality of a clinical treatment plan. However, when delivery uncertainties are present, the DVH may not always accurately describe the dose distribution actually delivered to the patient. We present a method, based on DVH formalism, to visualize the variability in the expected dosimetric outcome of a treatment plan. For a case of chordoma of the cervical spine, we compared 2 intensity modulated proton therapy plans. Treatment plan A was optimized based on dosimetric objectives alone (ie, desired target coverage, normal tissue tolerance). Plan B was created employing a published probabilistic optimization method that considered the uncertainties in patient setup and proton range in tissue. Dose distributions and DVH for both plans were calculated for the nominal delivery scenario, as well as for scenarios representing deviations from the nominal setup, and a systematic error in the estimate of range in tissue. The histograms from various scenarios were combined to create DVH bands to illustrate possible deviations from the nominal plan for the expected magnitude of setup and range errors. In the nominal scenario, the DVH from plan A showed superior dose coverage, higher dose homogeneity within the target, and improved sparing of the adjacent critical structure. However, when the dose distributions and DVH from plans A and B were recalculated for different error scenarios (eg, proton range underestimation by 3 mm), the plan quality, reflected by DVH, deteriorated significantly for plan A, while plan B was only minimally affected. In the DVH-band representation, plan A produced wider bands, reflecting its higher vulnerability to delivery errors, and uncertainty in the dosimetric outcome. The results illustrate that comparison of DVH for the nominal scenario alone does not provide any information about the relative sensitivity of dosimetric outcome to delivery uncertainties. Thus, such comparison may be misleading and may result in the selection of an inferior plan for delivery to a patient. A better-informed decision can be made if additional information about possible dosimetric variability is presented; for example, in the form of DVH bands. Copyright © 2012 American Society for Radiation Oncology. Published by Elsevier Inc. All rights reserved.

Analyzing Radio-Frequency Coverage for the ISS

NASA Technical Reports Server (NTRS)

Bolen, Steven M.; Sham, Catherine C.

2007-01-01

The Interactive Coverage Analysis Tool (iCAT) is an interactive desktop computer program serving to (1) support planning of coverage, and management of usage of frequencies, of current and proposed radio communication systems on and near the International Space Station (ISS) and (2) enable definition of requirements for development of future such systems. The iCAT can also be used in design trade studies for other (both outer-space and terrestrial) communication systems. A user can enter the parameters of a communication-system link budget in a table in a worksheet. The nominal (onaxis) link values for the bit-to-noise-energy ratio, received isotropic power (RIP), carrier-to-noise ratio (C/N), power flux density (PFD), and link margin of the system are calculated and displayed in the table. Plots of field gradients for the RIP, C/N, PFD, and link margin are constructed in an ISS coordinate system, at a specified link range, for both the forward and return link parameters, and are displayed in worksheets. The forward and reverse link antenna gain patterns are also constructed and displayed. Line-of-sight (LOS) obstructions can be both incorporated into the gradient plots and displayed on separate plots.

The GalileoJupiter Probe Doppler Wind Experiment

NASA Astrophysics Data System (ADS)

Atkinson, D. H.

2001-09-01

The GalileoJupiter atmospheric entry probe was launched along with the Galileoorbiter spacecraft from Cape Canaveral in Florida, USA, on October 18, 1989. Following a cruise of greater than six years, the probe arrived at Jupiter on December 7, 1995. During its 57-minute descent, instruments on the probe studied the atmospheric composition and structure, the clouds, lightning, and energy structure of the upper Jovian atmosphere. One of the two radio channels over which the experiment data was transmitted to the orbiter was driven by an ultrastable oscillator. All motions of the probe and orbiter, including the speed of probe descent, Jupiter's rotation, and the atmospheric winds, contributed to a Doppler shift of the probe radio frequency. By accurately measuring the frequency of the probe radio signal, an accurate time history of the probe-orbiter relative motions could be reconstructed. Knowledge of the nominal probe and orbiter trajectories allowed the nominal Doppler shift to be removed from the probe radio frequency leaving a measurable frequency residual arising primarily from the zonal winds in Jupiter's atmosphere, and micromotions of the probe arising from probe spin, swing under the parachute, atmospheric turbulence, and aerodynamic effects. Assuming that the zonal horizontal winds dominate the residual probe motion, a profile of frequency residuals was generated. Inversion of the frequency residuals resulted in the first in situ measurements of the vertical profile of Jupiter's deep zonal winds. It is found that beneath 700 mb, the winds are strong and prograde, rising rapidly to 170 m/s between 1 and 4 bars. Beneath 4 bars to 21 bars, the depth at which the link with the probe was lost, the winds remain constant and strong. When corrections for the high temperatures encountered by the probe are considered, there is no evidence of diminishing or strengthening of the zonal winds in the deepest regions explored by the Galileoprobe. Following the wind recovery, the frequency residuals offer tantalizing clues to microstructure in the atmospheric dynamics, including turbulence and wave motion.

Recoil-free Fraction in Amorphous and Nanocrystalline Aluminium Based Alloys

NASA Astrophysics Data System (ADS)

Sitek, Jozef

2008-10-01

Aluminium based rapidly quenched alloys of nominal composition Al90Fe7Nb3 and Al94Fe2V4 were studied by Mössbauer spectroscopy. We have measured the recoil-free fraction and thermal shift at room and liquid nitrogen temperature. The frequency modes of atomic vibrations were determined and consequently the characteristic Debye temperature was derived. Characteristic temperature calculated from f-factor was lower than those fitted from second order Doppler shift. This indicates the presence of different frequency modes for amorphous and nanocrystalline states.

Generation of 369.4 nm Radiation by Efficient Doubling of a Diode Laser

NASA Technical Reports Server (NTRS)

Williams, A.; Seidel, D. J.; Maleki, J.

1993-01-01

A resonant cavity second harmonic generation system has been developed to produce 369.4 nm radiation from a 738.8 nm diode laser with 10 mW nominal output power. This system utilizes a polarization technique to lock the cavity to the laser frequency. In this paper we report on an evaluation of the system using a Titanium:Sapphire laser as the input source, and preliminary results with a diode laser source. To our knowledge, this is the deepest uv light ever produced by frequency-doubling a diode laser.

The Response of a Mechanical Oscillator Due to Swept and Dithered Excitation

NASA Technical Reports Server (NTRS)

Davis, R. Benjamin; Durham, R. Caitlyn; Brown, Andrew M.

2010-01-01

A single degree-of-freedom oscillator subject to linearly swept and/or dithered excitation is considered. Dither refers to the variation of an excitation frequency about a given nominal, or primary, frequency. Dither in rocket engine turbopump shaft speeds can be an important consideration when analyzing the dynamic response of turbomachinery components such as turbine blades. Results indicate that the incorporation of dithered excitation into a fatigue analysis may extend the predicted fatigue life of the structure by a factor of two or more.

Some space shuttle tile/strain-isolator-pad sinusoidal vibration tests

NASA Technical Reports Server (NTRS)

Miserentino, R.; Pinson, L. D.; Leadbetter, S. A.

1980-01-01

Vibration tests were performed on the tile/strain-isolator-pad system used as thermal protection for the space shuttle orbiter. Experimental data on normal and in-plane vibration response and damping properties are presented. Three test specimens exhibited shear type motion during failures that occurred in the tile near the tile/strain-isolator-pad bond-line. A dynamic instability is described which has large in-plane motion at a frequency one-half that of the nominal driving frequency. Analysis shows that this phenomenon is a parametric response.

Earth Observing-1 Advanced Land Imager: Dark Current and Noise Characterization and Anomalous Detectors

NASA Technical Reports Server (NTRS)

Mendenhall, J. A.

2001-01-01

The dark current and noise characteristics of the Earth Observing-1 Advanced Land Imager measured during ground calibration at MIT Lincoln Laboratory are presented. Data were collected for the nominal focal plane operating temperature of 220 K as well as supplemental operating temperatures (215 and 225 K). Dark current baseline values are provided, and noise characterization includes the evaluation of white, coherent, low frequency, and high frequency components. Finally, anomalous detectors, characterized by unusual dark current, noise, gain, or cross-talk properties are investigated.

Cruise Report: Long-Range Ocean Acoustic Propagation EXperiment (LOAPEX)

DTIC Science & Technology

2005-04-01

starboard side was used. Both ends of the slip line shown ran through the crane hook to keep them vertical; a strip of masking tape was put around the...2150-3550 m nominal) with a 20-element, 700-in long array (3570- 4270 m nominal) to span the lower caustics in the acoustic arrival pattern with a...during the cruise. The critical equipment belonging to the ship included the stem A-frame, starboard A-frame, both of the ship’s cranes , CTD/rosette

Enhanced Master Controller Unit Tester

NASA Technical Reports Server (NTRS)

Benson, Patricia; Johnson, Yvette; Johnson, Brian; Williams, Philip; Burton, Geoffrey; McCoy, Anthony

2007-01-01

The Enhanced Master Controller Unit Tester (EMUT) software is a tool for development and testing of software for a master controller (MC) flight computer. The primary function of the EMUT software is to simulate interfaces between the MC computer and external analog and digital circuitry (including other computers) in a rack of equipment to be used in scientific experiments. The simulations span the range of nominal, off-nominal, and erroneous operational conditions, enabling the testing of MC software before all the equipment becomes available.

Using Dispersed Modes During Model Correlation

NASA Technical Reports Server (NTRS)

Stewart, Eric C.; Hathcock, Megan L.

2017-01-01

The model correlation process for the modal characteristics of a launch vehicle is well established. After a test, parameters within the nominal model are adjusted to reflect structural dynamics revealed during testing. However, a full model correlation process for a complex structure can take months of man-hours and many computational resources. If the analyst only has weeks, or even days, of time in which to correlate the nominal model to the experimental results, then the traditional correlation process is not suitable. This paper describes using model dispersions to assist the model correlation process and decrease the overall cost of the process. The process creates thousands of model dispersions from the nominal model prior to the test and then compares each of them to the test data. Using mode shape and frequency error metrics, one dispersion is selected as the best match to the test data. This dispersion is further improved by using a commercial model correlation software. In the three examples shown in this paper, this dispersion based model correlation process performs well when compared to models correlated using traditional techniques and saves time in the post-test analysis.

Review of probabilistic analysis of dynamic response of systems with random parameters

NASA Technical Reports Server (NTRS)

Kozin, F.; Klosner, J. M.

1989-01-01

The various methods that have been studied in the past to allow probabilistic analysis of dynamic response for systems with random parameters are reviewed. Dynamic response may have been obtained deterministically if the variations about the nominal values were small; however, for space structures which require precise pointing, the variations about the nominal values of the structural details and of the environmental conditions are too large to be considered as negligible. These uncertainties are accounted for in terms of probability distributions about their nominal values. The quantities of concern for describing the response of the structure includes displacements, velocities, and the distributions of natural frequencies. The exact statistical characterization of the response would yield joint probability distributions for the response variables. Since the random quantities will appear as coefficients, determining the exact distributions will be difficult at best. Thus, certain approximations will have to be made. A number of techniques that are available are discussed, even in the nonlinear case. The methods that are described were: (1) Liouville's equation; (2) perturbation methods; (3) mean square approximate systems; and (4) nonlinear systems with approximation by linear systems.

Polarized Power Spectra from HERA-19 Commissioning Data: Instrument Stability

NASA Astrophysics Data System (ADS)

Fox Fortino, Austin; Chichura, Paul; Igarashi, Amy; Kohn, Saul; Aguirre, James; HERA Collaboration

2018-01-01

The Epoch of Reionization (EoR) is a key period in the universe’s history, containing the formation of the first galaxies and large scale structures. Foreground emission is the limiting factor in detecting the 21 cm emission from the Epoch of Reionization (EoR). The HERA-19 low frequency radio interferometer aims to reduce the obfuscation from the foreground emission with its dish shaped antennae. We generate polarized 2D (cylindrically averaged) power spectra from seven days of observation from the HERA-19 2016 observation season in each of the four Stokes parameters I, Q, U, and V. These power spectra serve as a potent diagnostic tool that allow us to understand the instrument stability by comparison between nominally redundant baselines, and between observations of nominally the same astrophysical sky on successive days. The power spectra are expected to vary among nominally redundant measurements due to ionosphere fluctuations and thermal changes in the electronics and instrument beam patterns, as well as other factors. In this work we investigate the stability over time of these polarized power spectra, and use them to quantify the variation due to these effects.

Neuro-Fuzzy Computational Technique to Control Load Frequency in Hydro-Thermal Interconnected Power System

NASA Astrophysics Data System (ADS)

Prakash, S.; Sinha, S. K.

2015-09-01

In this research work, two areas hydro-thermal power system connected through tie-lines is considered. The perturbation of frequencies at the areas and resulting tie line power flows arise due to unpredictable load variations that cause mismatch between the generated and demanded powers. Due to rising and falling power demand, the real and reactive power balance is harmed; hence frequency and voltage get deviated from nominal value. This necessitates designing of an accurate and fast controller to maintain the system parameters at nominal value. The main purpose of system generation control is to balance the system generation against the load and losses so that the desired frequency and power interchange between neighboring systems are maintained. The intelligent controllers like fuzzy logic, artificial neural network (ANN) and hybrid fuzzy neural network approaches are used for automatic generation control for the two area interconnected power systems. Area 1 consists of thermal reheat power plant whereas area 2 consists of hydro power plant with electric governor. Performance evaluation is carried out by using intelligent (ANFIS, ANN and fuzzy) control and conventional PI and PID control approaches. To enhance the performance of controller sliding surface i.e. variable structure control is included. The model of interconnected power system has been developed with all five types of said controllers and simulated using MATLAB/SIMULINK package. The performance of the intelligent controllers has been compared with the conventional PI and PID controllers for the interconnected power system. A comparison of ANFIS, ANN, Fuzzy and PI, PID based approaches shows the superiority of proposed ANFIS over ANN, fuzzy and PI, PID. Thus the hybrid fuzzy neural network controller has better dynamic response i.e., quick in operation, reduced error magnitude and minimized frequency transients.

Investigation and Characterization of Acoustic Emissions of Tornadoes Using Arrays of Infrasound Sensors

NASA Astrophysics Data System (ADS)

Frazier, W. G.; Talmadge, C. L.; Waxler, R.; Knupp, K. R.; Goudeau, B.; Hetzer, C. H.

2017-12-01

Working in co-ordination with the NOAA Vortex Southeast (Vortex SE) research program, 9 infrasound sensor arrays were deployed at fixed sites across North Alabama, South-central Tennessee, and Northwest Georgia during March and April of 2017, to investigate the emission and characterization of infrasonic acoustic energy from tornadoes and related phenomena. Each array consisted of seven broadband acoustic sensors with calibrated frequency response from 0.02 Hz to 200 Hz. The arrays were configured in a pattern such that accurate bearings to acoustic sources could be obtained over a broad range of frequencies (nominally from 1 Hz to 100 Hz). Data were collected synchronously at a rate of 1000 samples per second. On 22 April 2017 a line of strong storms passed directly through the area being monitored producing at least three verified tornadoes. Two of these were rated at EF0 and the other an EF1. Subsequent processing of the data from several of the arrays revealed acoustic emissions from the tornadic storms ranging in frequencies below 1 Hz to frequencies greater than 10 Hz. Accurate bearings to the storms have been calculated from distances greater than 60 km. Preliminary analysis has revealed that continuous emissions occurred prior to the estimated touchdown times, while the storms were on the ground, and for short periods after the tornadoes lifted; however, the strongest emissions appeared to occur while the storms were on the ground. One of the storms passed near two arrays simultaneously, and therefore accurate an accurate track of the storm as it moved has been obtained only using the infrasound measurements. Initial results from the analysis of the infrasound data will be presented. Under Vortex SE meteorological data was collected on a large suite of sensors. Correlations between the infrasound data and the meteorological data will be investigated and discussed.

Physical Design and Dynamical Analysis of Resonant-Antiresonant Ag/MgO/GaSe/Al Optoelectronic Microwave Devices

NASA Astrophysics Data System (ADS)

Kmail, Renal R. N.; Qasrawi, A. F.

2015-11-01

In this work, the design and optical and electrical properties of MgO/GaSe heterojunction devices are reported and discussed. The device was designed using 0.4- μm-thick n-type GaSe as substrate for a 1.6- μm-thick p-type MgO optoelectronic window. The device was characterized by means of ultraviolet-visible optical spectrophotometry in the wavelength region from 200 nm to 1100 nm, current-voltage ( I- V) characteristics, impedance spectroscopy in the range from 1.0 MHz to 1.8 GHz, and microwave amplitude spectroscopy in the frequency range from 1.0 MHz to 3.0 GHz. Optical analysis of the MgO/GaSe heterojunction revealed enhanced absorbing ability of the GaSe below 2.90 eV with an energy bandgap shift from 2.10 eV for the GaSe substrate to 1.90 eV for the heterojunction design. On the other hand, analysis of I- V characteristics revealed a tunneling-type device conducting current by electric field-assisted tunneling of charged particles through a barrier with height of 0.81 eV and depletion region width of 670 nm and 116 nm when forward and reverse biased, respectively. Very interesting features of the device are observed when subjected to alternating current (ac) signal analysis. In particular, the device exhibited resonance-antiresonance behavior and negative capacitance characteristics near 1.0 GHz. The device quality factor was ˜102. In addition, when a small ac signal of Bluetooth amplitude (0.0 dBm) was imposed between the device terminals, the power spectra of the device displayed tunable band-stop filter characteristics with maximum notch frequency of 1.6 GHz. The energy bandgap discontinuity, the resonance-antiresonance behavior, the negative capacitance features, and the tunability of the electromagnetic power spectra at microwave frequencies nominate the Ag/MgO/GaSe/Al device as a promising optoelectronic device for use in multipurpose operations at microwave frequencies.

System and method for tuning adjusting the central frequency of a laser while maintaining frequency stabilization to an external reference

NASA Technical Reports Server (NTRS)

Livas, Jeffrey (Inventor); Thorpe, James I. (Inventor); Numata, Kenji (Inventor)

2011-01-01

A method and system for stabilizing a laser to a frequency reference with an adjustable offset. The method locks a sideband signal generated by passing an incoming laser beam through the phase modulator to a frequency reference, and adjusts a carrier frequency relative to the locked sideband signal by changing a phase modulation frequency input to the phase modulator. The sideband signal can be a single sideband (SSB), dual sideband (DSB), or an electronic sideband (ESB) signal. Two separate electro-optic modulators can produce the DSB signal. The two electro-optic modulators can be a broadband modulator and a resonant modulator. With a DSB signal, the method can introduce two sinusoidal phase modulations at the phase modulator. With ESB signals, the method can further drive the optical phase modulator with an electrical signal with nominal frequency OMEGA(sub 1) that is phase modulated at a frequency OMEGA(sub 2)

Flow-induced vibration testing of replacement thermowell designs

NASA Astrophysics Data System (ADS)

Haslinger, K. H.

2003-09-01

Inconel 600 Primary Water Stress Corrosion Cracking (PWSCC) in Nuclear Pressurized Water Reactors (PWRs) has necessitated the repair/replacement of various small bore nozzles. These repairs/replacements must be designed to avoid unwanted vibrations. So, to this end, new RTD-Thermowell-Nozzle replacement designs were developed and subjected to flow testing over a velocity range from 9.14 to 33.53m/s (30-110ft/s), and temperatures ranging from 121°C to 316°C (250-600°F). The replacement nozzles are welded on the pipe OD, rather than on the pipe ID. A split, tapered ferrule is used to support the nozzle tip inside the pipe bore. This maintains high thermowell tip-resonance frequencies with the objective of avoiding self-excitation from vortex shedding that is believed to have caused failures in an earlier design during initial, precritical plant startup testing. The flow testing was complicated by the small size of the thermowell tips (5.08mm or 0.2in ID), which necessitated use of a complement of low temperature and high temperature instrumentation. Since the high temperature device had an internal resonance (750Hz) within the frequency range of interest (0-2500Hz), adequate sensor correlations had to be derived from low temperature tests. The current nozzle/thermowell design was tested concurrently with two slight variations of the replacement design. The acceleration signals were acquired during incremental and continuous flow sweeps, nominally at 5kHz sampling rates and for time domain processing as high as 25kHz. Whereas vortex-shedding frequencies were predicted to prevail between 400 and 1500Hz, no such response was observed at these frequencies. Rather, the thermowell tips responded due to turbulent buffeting with a peak response that was related directly to flow velocity. Lift direction response was always larger than drag direction response. The thermowell tips also responded at their natural tip frequencies in a narrow band random fashion. At the higher flow rates, one replacement design experienced an instability mode leading to high tip stresses. Although this instability did not repeat, this particular design was eliminated from consideration. The second replacement design performed almost identically to the current in-plant design. The experimental data were used to extract forcing functions and thermowell responses that were used as input into the design calculations.

Induction motor control

NASA Technical Reports Server (NTRS)

Hansen, Irving G.

1990-01-01

Electromechanical actuators developed to date have commonly utilized permanent magnet (PM) synchronous motors. More recently switched reluctance (SR) motors have been advocated due to their robust characteristics. Implications of work which utilizes induction motors and advanced control techniques are discussed. When induction motors are operated from an energy source capable of controlling voltages and frequencies independently, drive characteristics are obtained which are superior to either PM or SR motors. By synthesizing the machine frequency from a high frequency carrier (nominally 20 kHz), high efficiencies, low distortion, and rapid torque response are available. At this time multiple horsepower machine drives were demonstrated, and work is on-going to develop a 20 hp average, 40 hp peak class of aerospace actuators. This effort is based upon high frequency power distribution and management techniques developed by NASA for Space Station Freedom.

Induction motor control

NASA Technical Reports Server (NTRS)

Hansen, Irving G.

1990-01-01

Electromechanical actuators developed to date have commonly ultilized permanent magnet (PM) synchronous motors. More recently switched reluctance (SR) motors have been advocated due to their robust characteristics. Implications of work which utilized induction motors and advanced control techniques are discussed. When induction motors are operated from an energy source capable of controlling voltages and frequencies independently, drive characteristics are obtained which are superior to either PM or SR motors. By synthesizing the machine frequency from a high-frequency carrier (nominally 20 kHz), high efficiencies, low distortion, and rapid torque response are available. At this time multiple horsepower machine drives were demonstrated, and work is on-going to develop a 20 hp average, 40 hp peak class of aerospace actuators. This effort is based upon high-frequency power distribution and management techniques developed by NASA for Space Station Freedom.

The experimental results of a self tuning adaptive controller using online frequency identification. [for Galileo spacecraft

NASA Technical Reports Server (NTRS)

Chiang, W.-W.; Cannon, R. H., Jr.

1985-01-01

A fourth-order laboratory dynamic system featuring very low structural damping and a noncolocated actuator-sensor pair has been used to test a novel real-time adaptive controller, implemented in a minicomputer, which consists of a state estimator, a set of state feedback gains, and a frequency-locked loop for real-time parameter identification. The adaptation algorithm employed can correct controller error and stabilize the system for more than 50 percent variation in the plant's natural frequency, compared with a 10 percent stability margin in frequency variation for a fixed gain controller having the same performance as the nominal plant condition. The very rapid convergence achievable by this adaptive system is demonstrated experimentally, and proven with simple, root-locus methods.

Antenna and propagation studies for spacecraft systems: Addendum to preflight SL-1/SL-3 Skylab VHF ranging coverage (early and late TPI)

NASA Technical Reports Server (NTRS)

Eisenhauer, D. R.; James, D. A.

1973-01-01

A preflight assessment is presented of the expected Skylab VHF ranging coverage for the rendezvous portion of the SL-1/SL-3 mission, assuming a 28 July 1973 launch date, for the alternative trajectory cases characterized by either an early TPI or a late TPI. In this assessment early TPI and late TPI are used to indicate a TPI maneuver occurring 10 minutes prior to or after the nominally scheduled TPI maneuver, respectively. The Saturn workshop (SWS) maintains a solar inertial (SI) attitude throughout rendezvous for both trajectory cases. The results summarized concern VHF ranging function performance during that period most likely to be affected by off-nominal TPI conditions, i.e., NSR (5:56 g.e.t.) to station keeping. Curves are presented which show the variation in received power levels on both spacecraft-to-spacecraft links from about 100 n.mi. range to CSM and SWS station keeping. Appropriate threshold levels are shown on these received power curves to indicate zero circuit margins for the ranging function.

SU-E-T-641: Proton Range Measurements Using a Geometrically Calibrated Liquid Scintillator Detector

DOE Office of Scientific and Technical Information (OSTI.GOV)

Hui, C; Robertson, D; Alsanea, F

2015-06-15

Purpose: The purpose of this work is to develop a geometric calibration method to accurately calculate physical distances within a liquid scintillator detector and to assess the accuracy, consistency, and robustness of proton beam range measurements when using a liquid scintillator detector system with the proposed geometric calibration process. Methods: We developed a geometric calibration procedure to accurately convert pixel locations in the camera frame into physical locations in the scintillator frame. To ensure accuracy, the geometric calibration was performed before each experiment. The liquid scintillator was irradiated with spot scanning proton beams of 94 energies in two deliveries. Amore » CCD camera was used to capture the two-dimensional scintillation light profile of each of the proton energies. An algorithm was developed to automatically calculate the proton range from the acquired images. The measured range was compared to the nominal range to assess the accuracy of the detector. To evaluate the robustness of the detector between each setup, the experiments were repeated on three different days. To evaluate the consistency of the measurements between deliveries, three sets of measurements were acquired for each experiment. Results: Using this geometric calibration procedure, the proton beam ranges measured using the liquid scintillator system were all within 0.3mm of the nominal range. The average difference between the measured and nominal ranges was −0.20mm. The delivery-to-delivery standard deviation of the proton range measurement was 0.04mm, and the setup-to-setup standard deviation of the measurement was 0.10mm. Conclusion: The liquid scintillator system can measure the range of all 94 beams in just two deliveries. With the proposed geometric calibration, it can measure proton range with sub-millimeter accuracy, and the measurements were shown to be consistent between deliveries and setups. Therefore, we conclude that the liquid scintillator system provides a reliable and convenient tool for proton range measurement. This project was supported in part by award number CA182450 from the National Cancer Institute.« less

75 FR 16910 - Information Reporting Program Advisory Committee (IRPAC); Nominations

Federal Register 2010, 2011, 2012, 2013, 2014

2010-04-02

... leadership to provide recommendations on a wide range of information reporting administration issues..., insurance companies, state tax administration, colleges and universities, securities, payroll, foreign...

SU-D-201-04: Evaluation of Elekta Agility MLC Performance Using Statistical Process Control

DOE Office of Scientific and Technical Information (OSTI.GOV)

Meyers, SM; Balderson, MJ; Letourneau, D

2016-06-15

Purpose: to evaluate the performance and stability of the Elekta Agility MLC model using an automated quality control (QC) test in combination with statistical process control tools. Methods: Leaf positions were collected daily for 11 Elekta units over 5–19 months using the automated QC test, which analyzes 23 MV images to determine the location of MLC leaves relative to the radiation isocenter. The leaf positions are measured at 5 nominal positions, and images are acquired at collimator 0° and 180° to capture all MLC leaves in the field-of-view. Leaf positioning accuracy was assessed using individual and moving range control charts.more » Control limits were recomputed following MLC recalibration (occurred 1–2 times for 4 units). Specification levels of ±0.5, ±1 and ±1.5mm were tested. The mean and range of duration between out-of-control and out-of-specification events were determined. Results: Leaf position varied little over time, as confirmed by very tight individual control limits (mean ±0.19mm, range 0.09–0.44). Mean leaf position error was −0.03mm (range −0.89–0.83). Due to sporadic out-of-control events, the mean in-control duration was 3.3 days (range 1–23). Data stayed within ±1mm specification for 205 days on average (range 3–372) and within ±1.5mm for the entire date range. Measurements stayed within ±0.5mm for 1 day on average (range 0–17); however, our MLC leaves were not calibrated to this level of accuracy. Conclusion: The Elekta Agility MLC model was found to perform with high stability, as evidenced by the tight control limits. The in-specification durations support the current recommendation of monthly MLC QC tests with a ±1mm tolerance. Future work is on-going to determine if Agility performance can be optimized further using high-frequency QC test results to drive recalibration frequency. Factors that can affect leaf positioning accuracy, including beam spot motion, leaf gain calibration, drifting leaves, and image artifacts, are under investigation.« less

High speed propeller performance and noise predictions at takeoff/landing conditions

NASA Technical Reports Server (NTRS)

Nallasamy, M.; Woodward, R. P.; Groeneweg, J. F.

1988-01-01

The performance and noise of a high speed SR-7A model propeller under takeoff/landing conditions are considered. The blade loading distributions are obtained by solving the three-dimensional Euler equations and the sound pressure levels are computed using a time domain approach. At the nominal takeoff operating point, the blade sections near the hub are lightly or negatively loaded. The chordwise loading distributions are distinctly different from those of cruise conditions. The noise of the SR-7A model propeller at takeoff is dominated by the loading noise, similar to that at cruise conditions. The waveforms of the acoustic pressure signature are nearly sinusoidal in the plane of the propeller. The computed directivity of the blade passing frequency tone agrees fairly well with the data at nominal takeoff blade angle.

High speed propeller performance and noise predictions at takeoff/landing conditions

NASA Technical Reports Server (NTRS)

Nallasamy, M.; Woodward, R. P.; Groeneweg, J. F.

1987-01-01

The performance and noise of a high speed SR-7A model propeller under takeoff/landing conditions are considered. The blade loading distributions are obtained by solving the three-dimensional Euler equations and the sound pressure levels are computed using a time domain approach. At the nominal takeoff operating point, the blade sections near the hub are lightly or negatively loaded. The chordwise loading distributions are distinctly different from those of cruise conditions. The noise of the SR-7A model propeller at takeoff is dominated by the loading noise, similar to that at cruise conditions. The waveforms of the acoustic pressure signature are nearly sinusoidal in the plane of the propeller. The computed directivity of the blade passing frequency tone agrees fairly well with the data at nominal takeoff blade angle.

Superparamagnetic and ferrimagnetic behavior of nanocrystalline ZnO(MnO)

NASA Astrophysics Data System (ADS)

Kuryliszyn-Kudelska, I.; Dobrowolski, W.; Arciszewska, M.; Romčević, N.; Romčević, M.; Hadžić, B.; Sibera, D.; Narkiewicz, U.

2018-04-01

We have studied the magnetic properties of nanocrystals of ZnO:MnO prepared by traditional wet chemistry method. The detailed structural and morphological characterization was performed. The results of systematic measurements of AC magnetic susceptibility as a function of temperature and frequency as well as DC magnetization are reported. We observed two different types of magnetic behavior depending on the concentration doping. For samples with low nominal content (up to 30 wt% of MnO), superparamagnetic behavior was observed. We attribute the observed superparamagnetism to the presence of nanosized ZnMnO3 phase. For nanocrystals doped above nominal 60 wt% of MnO ferrimagnetism was detected with TC at around 42 K. This magnetic behavior we assign to the presence of nanosized Mn3O4 phase.

Hysteresis, phase transitions, and dangerous transients in electrical power distribution systems

NASA Astrophysics Data System (ADS)

Duclut, Charlie; Backhaus, Scott; Chertkov, Michael

2013-06-01

The majority of dynamical studies in power systems focus on the high-voltage transmission grids where models consider large generators interacting with crude aggregations of individual small loads. However, new phenomena have been observed indicating that the spatial distribution of collective, nonlinear contribution of these small loads in the low-voltage distribution grid is crucial to the outcome of these dynamical transients. To elucidate the phenomenon, we study the dynamics of voltage and power flows in a spatially extended distribution feeder (circuit) connecting many asynchronous induction motors and discover that this relatively simple 1+1 (space+time) dimensional system exhibits a plethora of nontrivial spatiotemporal effects, some of which may be dangerous for power system stability. Long-range motor-motor interactions mediated by circuit voltage and electrical power flows result in coexistence and segregation of spatially extended phases defined by individual motor states, a “normal” state where the motors’ mechanical (rotation) frequency is slightly smaller than the nominal frequency of the basic ac flows and a “stalled” state where the mechanical frequency is small. Transitions between the two states can be initiated by a perturbation of the voltage or base frequency at the head of the distribution feeder. Such behavior is typical of first-order phase transitions in physics, and this 1+1 dimensional model shows many other properties of a first-order phase transition with the spatial distribution of the motors’ mechanical frequency playing the role of the order parameter. In particular, we observe (a) propagation of the phase-transition front with the constant speed (in very long feeders) and (b) hysteresis in transitions between the normal and stalled (or partially stalled) phases.

Hysteresis, phase transitions, and dangerous transients in electrical power distribution systems.

PubMed

Duclut, Charlie; Backhaus, Scott; Chertkov, Michael

2013-06-01

The majority of dynamical studies in power systems focus on the high-voltage transmission grids where models consider large generators interacting with crude aggregations of individual small loads. However, new phenomena have been observed indicating that the spatial distribution of collective, nonlinear contribution of these small loads in the low-voltage distribution grid is crucial to the outcome of these dynamical transients. To elucidate the phenomenon, we study the dynamics of voltage and power flows in a spatially extended distribution feeder (circuit) connecting many asynchronous induction motors and discover that this relatively simple 1+1 (space+time) dimensional system exhibits a plethora of nontrivial spatiotemporal effects, some of which may be dangerous for power system stability. Long-range motor-motor interactions mediated by circuit voltage and electrical power flows result in coexistence and segregation of spatially extended phases defined by individual motor states, a "normal" state where the motors' mechanical (rotation) frequency is slightly smaller than the nominal frequency of the basic ac flows and a "stalled" state where the mechanical frequency is small. Transitions between the two states can be initiated by a perturbation of the voltage or base frequency at the head of the distribution feeder. Such behavior is typical of first-order phase transitions in physics, and this 1+1 dimensional model shows many other properties of a first-order phase transition with the spatial distribution of the motors' mechanical frequency playing the role of the order parameter. In particular, we observe (a) propagation of the phase-transition front with the constant speed (in very long feeders) and (b) hysteresis in transitions between the normal and stalled (or partially stalled) phases.

Electron cyclotron heating can drastically alter reversed shear Alfvén eigenmode activity in DIII-D through finite pressure effects

NASA Astrophysics Data System (ADS)

Van Zeeland, M. A.; Heidbrink, W. W.; Sharapov, S. E.; Spong, D.; Cappa, A.; Chen, Xi; Collins, C.; García-Muñoz, M.; Gorelenkov, N. N.; Kramer, G. J.; Lauber, P.; Lin, Z.; Petty, C.

2016-11-01

A recent DIII-D experiment investigating the impact of electron cyclotron heating (ECH) on neutral beam driven reversed shear Alfvén eigenmode (RSAE) activity is presented. The experiment includes variations of ECH injection location and timing, current ramp rate, beam injection geometry (on/off-axis), and neutral beam power. Essentially all variations carried out in this experiment were observed to change the impact of ECH on AE activity significantly. In some cases, RSAEs were observed to be enhanced with ECH near the off-axis minimum in magnetic safety factor ({{q}\\min} ), in contrast to the original DIII-D experiments where the modes were absent when ECH was deposited near {{q}\\min} . It is found that during intervals when the geodesic acoustic mode (GAM) frequency at {{q}\\min} is elevated and the calculated RSAE minimum frequency, including contributions from thermal plasma gradients, is very near or above the nominal TAE frequency (f TAE), RSAE activity is not observed or RSAEs with a much reduced frequency sweep range are found. This condition is primarily brought about by ECH modification of the local electron temperature (T e) which can raise both the local T e at {{q}\\min} as well as its gradient. A q-evolution model that incorporates this reduction in RSAE frequency sweep range is in agreement with the observed spectra and appears to capture the relative balance of TAE or RSAE-like modes throughout the current ramp phase of over 38 DIII-D discharges. Detailed ideal MHD calculations using the NOVA code show both modification of plasma pressure and pressure gradient at {{q}\\min} play an important role in modifying the RSAE activity. Analysis of the ECH injection near the {{q}\\min} case where no frequency sweeping RSAEs are observed shows the typical RSAE is no longer an eigenmode of the system. What remains is an eigenmode with poloidal harmonic content reminiscent of the standard RSAE, but absent of the typical frequency sweeping behavior. The remaining eigenmode is also often strongly coupled to gap TAEs. Analysis with the non-perturbative gyro fluid code TAEFL confirms this change in RSAE activity and also shows a large drop in the resultant mode growth rates.

Electron cyclotron heating can drastically alter reversed shear Alfvén eigenmode activity in DIII-D through finite pressure effects

DOE PAGES

Van Zeeland, M. A.; Heidbrink, W. W.; Sharapov, S. E.; ...

2016-07-22

Here, a recent DIII-D experiment investigating the impact of electron cyclotron heating (ECH) on neutral beam driven reversed shear Alfvén eigenmode (RSAE) activity is presented. The experiment includes variations of ECH injection location and timing, current ramp rate, beam injection geometry (on/off-axis), and neutral beam power. Essentially all variations carried out in this experiment were observed to change the impact of ECH on AE activity significantly. In some cases, RSAEs were observed to be enhanced with ECH near the off-axis minimum in magnetic safety factor (more » $${{q}_{\\min}}$$ ), in contrast to the original DIII-D experiments where the modes were absent when ECH was deposited near $${{q}_{\\min}}$$ . It is found that during intervals when the geodesic acoustic mode (GAM) frequency at $${{q}_{\\min}}$$ is elevated and the calculated RSAE minimum frequency, including contributions from thermal plasma gradients, is very near or above the nominal TAE frequency (f TAE), RSAE activity is not observed or RSAEs with a much reduced frequency sweep range are found. This condition is primarily brought about by ECH modification of the local electron temperature (T e) which can raise both the local T e at $${{q}_{\\min}}$$ as well as its gradient. A q-evolution model that incorporates this reduction in RSAE frequency sweep range is in agreement with the observed spectra and appears to capture the relative balance of TAE or RSAE-like modes throughout the current ramp phase of over 38 DIII-D discharges. Detailed ideal MHD calculations using the NOVA code show both modification of plasma pressure and pressure gradient at $${{q}_{\\min}}$$ play an important role in modifying the RSAE activity. Analysis of the ECH injection near the $${{q}_{\\min}}$$ case where no frequency sweeping RSAEs are observed shows the typical RSAE is no longer an eigenmode of the system. What remains is an eigenmode with poloidal harmonic content reminiscent of the standard RSAE, but absent of the typical frequency sweeping behavior. The remaining eigenmode is also often strongly coupled to gap TAEs. Analysis with the non-perturbative gyro fluid code TAEFL confirms this change in RSAE activity and also shows a large drop in the resultant mode growth rates.« less

The magnetic field investigation on the ARASE (ERG) mission: Data characteristics and initial scientific results

NASA Astrophysics Data System (ADS)

Matsuoka, A.; Teramoto, M.; Nomura, R.; Nose, M.; Fujimoto, A.; Tanaka, Y.; Shinohara, M.; Nagatsuma, T.; Shiokawa, K.; Obana, Y.; Miyoshi, Y.; Takashima, T.; Shinohara, I.

2017-12-01

The ARASE (ERG) satellite was successfully launched on December 20 2016. A fluxgate magnetometer (MGF) was built for the ARASE satellite to measure DC and low-frequency magnetic field. The requirements to the magnetic field measurements by ARASE was defined as (1) accuracy of the absolute field intensity is within 5 nT (2) angular accuracy of the field direction is within 1 degree (3) measurement frequency range is from DC to 60Hz or wider. MGF measures the vector magnetic field with the original sampling frequency of 256 Hz. The dynamic range is switched between +/-8000nT and +/- 60000nT according to the background field intensity. The MGF initial checkout was carried on January 10th 2017, when the MGF normal performance and downlinked data were confirmed. The 5-m length MAST for the sensor was deployed on 17th January. The nominal operation of MGF started in March 2017. The MGF data are calibrated based on the results from the ground experiments and in-orbit data analysis. The MGF CDF files are distributed by the ARASE Science Center and available by Space Physics Environment Data Analysis Software (SPEDAS). The acceleration process of the charged particles in the inner magnetosphere is considered to be closely related to the deformation and perturbation of the magnetic field. Accurate measurement of the magnetic field is required to understand the acceleration mechanism of the charged particles, which is one of the major scientific objectives of the ARASE mission. We designed a fluxgate magnetometer which is optimized to investigate following topics; (1) accurate measurement of the background magnetic field - the deformation of the magnetic field and its relationship with the particle acceleration. (2) MHD waves - measurement of the ULF electromagnetic waves of frequencies about 1mHz (Pc4-5), and investigation of the radiation-belt electrons radially diffused by the resonance with the ULF waves. (3) EMIC waves - measurement of the electromagnetic ion-cyclotron waves of frequencies about 1Hz, and investigation of the ring-current ions and radiation-belt electrons dissipated by the interaction with the EMIC waves.These scientific subjects are now investigated by the ARASE working team colleagues.

Emergency nurses' decisions regarding frequency and nature of vital sign assessment.

PubMed

Lambe, Katherine; Currey, Judy; Considine, Julie

2017-07-01

To explore the factors emergency nurses use to inform their decisions regarding frequency and nature of vital sign assessment. Research related to clinical deterioration and vital sign assessment in the emergency department is in its infancy. Studies to date have explored the frequency of vital sign assessment in the emergency department; however, there are no published studies that have examined factors that emergency nurses use to inform their decisions regarding frequency and nature of ongoing vital sign assessment. A prospective exploratory design was used. Data were collected using a survey consisting of eight patient vignettes. The study was conducted in one emergency department in metropolitan Melbourne. Participants were emergency nurses permanently employed at the study site. A 96% response rate was achieved (n = 47/49). The most common frequency of patient reassessment nominated by participants was 15 or 30 minutely, with an equal number of participants choosing these frequency intervals. Abnormality in initial vital sign parameters was the most common factor identified for choosing either a 15- or 30-minute assessment interval. Frequency of assessment decisions was influenced by years of emergency nursing experience in one vignette and level of postgraduate qualification in three vignettes. Heart rate, respiratory rate and blood pressure were all nominated by over 80% of participants as vital signs that participants considered important for reassessment. The frequency and nature of vital signs selected varied according to vignette content. There were significant negative correlations between assessment of conscious state and years of nursing experience and assessment of respiratory rate and years of emergency nursing experience. Level of postgraduate qualification did not influence selection of parameters for reassessment. Emergency nurses are tailoring vital sign assessment to patients' clinical status, and nurses are integrating known vital sign data into vital sign decision-making. Accurate assessment and interpretation of vital sign data is fundamental to patient safety. Emergency nurses are responsible for the initial and ongoing assessment of undiagnosed or undifferentiated patients. Prior to medical assessment, emergency nurses are solely responsible for patient assessment, escalation of care and implementation of interventions within nursing scope of practice. © 2016 John Wiley & Sons Ltd.

Regulation control and energy management scheme for wireless power transfer

DOEpatents

Miller, John M.

2015-12-29

Power transfer rate at a charging facility can be maximized by employing a feedback scheme. The state of charge (SOC) and temperature of the regenerative energy storage system (RESS) pack of a vehicle is monitored to determine the load due to the RESS pack. An optimal frequency that cancels the imaginary component of the input impedance for the output signal from a grid converter is calculated from the load of the RESS pack, and a frequency offset f* is made to the nominal frequency f.sub.0 of the grid converter output based on the resonance frequency of a magnetically coupled circuit. The optimal frequency can maximize the efficiency of the power transfer. Further, an optimal grid converter duty ratio d* can be derived from the charge rate of the RESS pack. The grid converter duty ratio d* regulates wireless power transfer (WPT) power level.

Zirconium nitride precipitation in nominally pure yttria-stabilized zirconia

DOE Office of Scientific and Technical Information (OSTI.GOV)

Gomez-Garcia, D.; Martinez-Fernandez, J.; Dominguez-Rodriguez, A.

Nominally pure yttria-stabilized zirconia alloys are shown to contain unexpectedly large amounts of dissolved nitrogen. Its presence in the lattice was detected through the observation of large precipitates in alloys with three different concentrations of yttria deformed in compression in argon in the temperature range 1,600--1,800 C. Electron diffraction, EDS and PEELS analyses, and Moire imaging were used to identify the precipitates as ZrN. The possible origin of the nitrogen, its likely effects on properties, and the role of annealing atmosphere are briefly discussed.

Space shuttle: Heat transfer rate measurements of North American Rockwell orbiter (161B) at nominal Mach number of 8

NASA Technical Reports Server (NTRS)

Warmbrod, J. D.; Martindale, W. R.; Matthews, R. K.

1971-01-01

Plots and tables which determine detailed heat transfer distributions on phase B space shuttle configurations are presented. A thin-skinned thermocouple was used to measure the reentry events of the delta wing orbiter. Data was obtained at a nominal Mach number of 8 and free stream Reynolds numbers ranging from 0.83 x 10 to the 6th power to 3.76 x 10 to the 6th power per foot. Angle of attack was varied from -5 to 50 degrees.

Fatigue Crack Topography.

DTIC Science & Technology

1984-01-01

nominal cycle frequency of 15 Hz. Buckling of the specimens during compression loading was prevented by felt-lined aluminium alloy antibuckling guides...evaluating ciack initiation time and crack propagation, prgram I was used for performing the major fatigue test with the aircraft structure. In...direction of the notch to prevent scratches in the through-the-thickness direction. Prior to testing, the notch surfaces were lightly etched to reveal

The Stability of GPS Carrier-Phase Receivers

DTIC Science & Technology

2010-11-01

Frequency Transfer ( TWSTFT ) method [2]. For both CP and TWSTFT , accuracy in time transfer is achieved through special calibration efforts that retain...View (CV) receivers and TWSTFT equipment. Many of these geodetic receivers operate continuously within the International GNSS Service (IGS), and...with TWSTFT , GPS CV, and GPS P3. If ionosphere-free measurements are used in combination with nominally compensated tropospheric corrections, a

Multiplexing Transducers Based on Tunnel-Diode Oscillators

NASA Technical Reports Server (NTRS)

Chui, Talso; Penanen, Konstantin; Young, Joseph

2006-01-01

Multiplexing and differential transducers based on tunnel-diode oscillators (TDOs) would be developed, according to a proposal, for operation at very low and/or widely varying temperatures in applications that involve requirements to minimize the power and mass of transducer electronic circuitry. It has been known since 1975 that TDOs are useful for making high-resolution (of the order of 10(exp -9)) measurements at low temperatures. Since that time, TDO transducers have been found to offer the following additional advantages, which the present proposal is intended to exploit: TDO transducers can operate at temperatures ranging from 1 K to about 400 K. Most electronic components other than tunnel diodes do not operate over such a wide temperature range. TDO transducers can be made to operate at very low power - typically, <1 mW. Inasmuch as the response of a TDO transducer is a small change in an arbitrarily set oscillation frequency, the outputs of many TDOs operating at sufficiently different set frequencies can be multiplexed through a single wire. Inasmuch as frequencies can be easily subtracted by means of mixing circuitry, one can easily use two TDOs to make differential measurements. Differential measurements are generally more precise and less susceptible to environmental variations than are absolute measurements. TDO transducers are tolerant to ionizing radiation. Ultimately, the response of a TDO transducer is measured by use of a frequency counter. Because frequency counting can be easily implemented by use of clock signals available from most microprocessors, it is not necessary to incorporate additional readout circuitry that would, if included, add to the mass and power consumption of the transducer circuitry. In one example of many potential variations on the basic theme of the proposal, the figure schematically depicts a conceptual differential-pressure transducer containing a symmetrical pair of TDOs. The differential pressure would be exerted on an electrically conductive and grounded diaphragm, which, at zero differential pressure, would nominally be sprung to a middle position between two capacitor plates that would be parts of the two TDOs. The frequencies of the two TDOs would vary in opposite directions as variations in differential pressure bent the diaphragm away from one capacitor plate and toward the other. The outputs of the TDOs would be mixed and lowpass filtered to obtain a signal at the difference between the frequencies of the two TDOs. The difference frequency would be measured by a frequency counter and converted to differential pressure by a computer.

43 CFR 3922.10 - Application processing fee.

Code of Federal Regulations, 2011 CFR

2011-10-01

... MANAGEMENT, DEPARTMENT OF THE INTERIOR RANGE MANAGEMENT (4000) OIL SHALE LEASING Application Processing... process for a competitive oil shale lease is as follows: (1) The applicant nominating the tract for...

A New Global Group Velocity Dataset for Constraining Crust and Upper Mantle Properties

NASA Astrophysics Data System (ADS)

Ma, Z.; Masters, G.; Laske, G.; Pasyanos, M. E.

2010-12-01

We are improving our CRUST2.0 to a new LITHO1.0 model, refining the nominal resolution to 1 degree and including lithospheric structure. The new model is constrained by many datasets, including very large datasets of surface wave group velocity built using a new, efficient measurement technique. This technique starts in a similar fashion to the traditional frequency-time analysis, but instead of making measurements for all frequencies for a single source-station pair, we apply cluster analysis to make measurements for all recordings for a single event at a single target frequency. By changing the nominal frequencies of the bandpass filter, we filter each trace until the centroid frequency of the band-passed spectrum matches the target frequency. We have processed all the LH data from IRIS (and some of the BH data from PASSCAL experiments and the POLARIS network) from 1976 to 2007. The Rayleigh wave group velocity data set is complete from 10mHz to 40mHz at increments of 2.5mHz. The data set has about 330000 measurements for 10 and 20mHz, 200000 for 30mHz and 110000 for 40mHz. We are also building a similar dataset for Love waves, though its size will be about half that of the Rayleigh wave dataset. The SMAD of the group arrival time difference between our global dataset and other more regional datasets is about 12 seconds for 20mHz, 9 seconds for 30mHz, and 7 seconds for 40mHz. Though the discrepancies are about twice as big as our measurement precision (estimated by looking at group arrival time differences between closely-spaced stations), it is still much smaller than the signal in the data (e.g., the group arrival time for 20mHz can differ from the prediction of a 1D Earth by over 250 seconds). The fact that there is no systematic bias between the datasets encourages us to combine them to improve coverage of some key areas. Group velocity maps inverted from the combined datasets show many interesting signals though the dominant signal is related to variations in crustal thickness. For 20mHz, group velocity perturbations from the global mean range from -25% to 11%, with a standard deviation of 4%. We adjust the smoothing of lateral structure in the inversion so that the error of the inferred group velocity is nearly uniform globally. For 20mHz, a 0.1% error in group velocity leads to resolution of features of dimension 9 degrees or less everywhere. The resolution in Eurasia is 5.5 degrees and in N. America is 4.5-5 degrees. For 30mHz, for the same 0.1% error, we can resolve structure of 10 degrees globally, 6.5 degrees for Eurasia and 5.5 degree for N. America.

A Beat Frequency RF Modulator for Generation of Low Repetition Rate Electron Microbunches for the CEBAF Polarized Source

DOE Office of Scientific and Technical Information (OSTI.GOV)

John Musson; Reza Kazimi; Benard Poelker

2007-06-25

Fiber-based drive lasers now produce all of the spin-polarized electron beams at CEBAF/Jefferson Lab. The flexibility of these drive lasers, combined with the existing three-beam CEBAF photoinjector Chopper, provides a means to implement a beat frequency technique to produce long time intervals between individual electron microbunches (tens of nanoseconds) by merely varying the nominal 499 MHz drive laser frequency by < 20%. This submission describes the RF Laser modulator that uses a divider and heterodyne scheme to maintain coherence with the accelerator Master Oscillator (MO), while providing delay resolution in increments of 2ns. Some possible uses for such a beammore » are discussed as well as intended future development.« less

MSL-2 accelerometer data results

NASA Technical Reports Server (NTRS)

Henderson, Fred

1990-01-01

The Materials Science Laboratory-2 (MSL-2) mission flew the Marshall Space Flight Center-developed Linear Triaxial Accelerometer (LTA) on the Space Transportation System (STS) 61-C Shuttle mission launched January 21, 1986. Flight data were analyzed to verify the quietness of the MSL carrier and to characterize the acceleration environment for future MSL users. The MSL was found to introduce no significant experiment acceleration; and the effects of crew treadmill exercise, Orbiter vernier engine firings, and other routine flight occurrences were established. The LTA was found to be well suited for measuring nominal to very quiet STS acceleration levels at frequencies below 50 Hz. Special processing was used to examine the low-frequency spectrum and to establish the effective rms amplitude associated with dominant frequencies.

Research of microwave scattering properties of snow fields

NASA Technical Reports Server (NTRS)

Angelakos, D. J.

1978-01-01

The results obtained in the research program of microwave scattering properties of snow fields are presented. Experimental results are presented showing backscatter dependence on frequency (5.8-8.0 GHz), angle of incidence (0-60 degrees), snow wetness (time of day), and frequency modulation (0-500 MHz). Theoretical studies are being made of the inverse scattering problem yielding some preliminary results concerning the determination of the dielectric constant of the snow layer. The experimental results lead to the following conclusions: snow layering affects backscatter, layer response is significant up to 45 degrees of incidence, wetness modifies snow layer effects, frequency modulation masks the layer response, and for the proper choice of probing frequency and for nominal snow depths, it appears to be possible to measure the effective dielectric constant and the corresponding water content of a snow pack.

Combined feedforward and model-assisted active disturbance rejection control for non-minimum phase system.

PubMed

Sun, Li; Li, Donghai; Gao, Zhiqiang; Yang, Zhao; Zhao, Shen

2016-09-01

Control of the non-minimum phase (NMP) system is challenging, especially in the presence of modelling uncertainties and external disturbances. To this end, this paper presents a combined feedforward and model-assisted Active Disturbance Rejection Control (MADRC) strategy. Based on the nominal model, the feedforward controller is used to produce a tracking performance that has minimum settling time subject to a prescribed undershoot constraint. On the other hand, the unknown disturbances and uncertain dynamics beyond the nominal model are compensated by MADRC. Since the conventional Extended State Observer (ESO) is not suitable for the NMP system, a model-assisted ESO (MESO) is proposed based on the nominal observable canonical form. The convergence of MESO is proved in time domain. The stability, steady-state characteristics and robustness of the closed-loop system are analyzed in frequency domain. The proposed strategy has only one tuning parameter, i.e., the bandwidth of MESO, which can be readily determined with a prescribed robustness level. Some comparative examples are given to show the efficacy of the proposed method. This paper depicts a promising prospect of the model-assisted ADRC in dealing with complex systems. Copyright © 2016 ISA. Published by Elsevier Ltd. All rights reserved.

Life Cycle Testing of Viscoelastic Material for Hubble Space Telescope Solar Array 3 Damper

NASA Technical Reports Server (NTRS)

Maly, Joseph R.; Reed, Benjamin B.; Viens, Michael J.; Parker, Bradford H.; Pendleton, Scott C.

2003-01-01

During the March 2002 Servicing Mission by Space Shuttle (STS 109), the Hubble Space Telescope (HST) was refurbished with two new solar arrays that now provide all of its power. These arrays were built with viscoelastic/titanium dampers, integral to the supporting masts, which reduce the interaction of the wing bending modes with the Telescope. Damping of over 3% of critical was achieved. To assess the damper s ability to maintain nominal performance over the 10-year on-orbit design goal, material specimens were subjected to an accelerated life test. The test matrix consisted of scheduled events to expose the specimens to pre-determined combinations of temperatures, frequencies, displacement levels, and numbers of cycles. These exposure events were designed to replicate the life environment of the damper from fabrication through testing to launch and life on-orbit. To determine whether material degradation occurred during the exposure sequence, material performance was evaluated before and after the accelerated aging with complex stiffness measurements. Based on comparison of pre- and post-life-cycle measurements, the material is expected to maintain nominal performance through end of life on-orbit. Recent telemetry from the Telescope indicates that the dampers are performing nominally.

The radial transmission line as a broad-band shielded exposure system for microwave irradiation of large numbers of culture flasks.

PubMed

Moros, E G; Straube, W L; Pickard, W F

1999-01-01

The problem of simultaneously exposing large numbers of culture flasks at nominally equivalent incident power densities and with good thermal control is considered, and the radial transmission line (RTL) is proposed as a solution. The electromagnetic design of this structure is discussed, and an extensively bench-tested realization is described. Referred to 1 W of net forward power, the following specific absorption rate (SAR) data were obtained: at 835.62 MHz, 16.0+/-2.5 mW/kg (mean+/-SD) with range (11-22); at 2450 MHz, 245+/-50 mW/kg with range (130-323). Radio-frequency interference from an RTL driven at roughly 100 W is so low as to be compatible with a cellular base station only 500 m distant. To avoid potential confounding by temperature differences among as many as 144 T-75 flasks distributed over 9 RTLs (six irradiates and three shams), temperature within all flasks was controlled to 37.0+/-0.3 degrees C. Experience with over two years of trouble-free operation suggests that the RTL offers a robust, logistically friendly, and environmentally satisfactory solution to the problem of large-scale in vitro experiments in bioelectromagnetics.

Validity of a measure to assess healthy eating and physical activity policies and practices in Australian childcare services.

PubMed

Dodds, Pennie; Wyse, Rebecca; Jones, Jannah; Wolfenden, Luke; Lecathelinais, Christophe; Williams, Amanda; Yoong, Sze Lin; Finch, Meghan; Nathan, Nicole; Gillham, Karen; Wiggers, John

2014-06-09

Childcare services represent a valuable obesity prevention opportunity, providing access to a large portion of children at a vital point in their development. Few rigorously validated measures exist to measure healthy eating and physical activity policies and practices in this setting, and no such measures exist that are specific to the childcare setting in Australia. This was a cross sectional study, comparing two measures (pen and paper survey and observation) of healthy eating and physical activity policies and practices in childcare services. Research assistants attended consenting childcare services (n = 42) across the Hunter region of New South Wales, Australia and observed practices for one day. Nominated Supervisors and Room Leaders of the service also completed a pen and paper survey during the day of observation. Kappa statistics and proportion agreement were calculated for a total of 43 items relating to healthy eating and physical activity policies and practices. Agreement ranged from 38%-100%. Fifty one percent of items showed agreement of greater than or equal to 80%. Items assessing the frequency with which staff joined in active play with children reported the lowest percent agreement, while items assessing availability of beverages such as juice, milk and cordial, as well as the provision of foods such as popcorn, pretzels and sweet biscuits, reported the highest percent agreement. Kappa scores ranged from -0.06 (poor agreement) to 1 (perfect agreement). Of the 43 items assessed, 27 were found to have moderate or greater agreement. The study found that Nominated Supervisors and Room Leaders were able to accurately report on a number of healthy eating and physical activity policies and practices. Items assessing healthy eating practices tended to have higher kappa scores than those assessing physical activity related policies or practices. The tool represents a useful instrument for public health researchers and policy makers working in this setting.

DOE Office of Scientific and Technical Information (OSTI.GOV)

Langner, U; Langen, K

Purpose: To investigate the effect of spot size variation as function of gantry angle on the quality of treatment plans for pencil beam scanning proton plans. Method: Three homogeneous 26×26×7cm dose volumes with different ranges and SOBPs were delivered on the matrixxPT 2D array at gantry angles of 0 and 270 degrees. The spot size sigma varies by 1.8, 7.8, and 1.4%, for nominal energies of 215, 183, and 103 MeV (Range 29, 22, and 8cm, respectively). The resulting dose planes are compared and evaluated with the gamma index for 2%/2mm and 1%/1mm criteria. Results: Patient specific QA is performedmore » at a gantry angle of 0 degrees. However, beam sigmas vary as function of gantry angle because of the beam optics for each gantry. This will cause differences between the delivered and planned treatment plans. Delivered plans were compared and a gamma pass rate of 96.5% for criteria of 2%/2mm and 91.4% for 1%/1mm were seen for plans with a nominal energy of 183 MeV. For plans with a nominal energy of 103 MeV, gamma pass rates of 97.3% for 2%/2mm and 91.5% for 1%/1mm were seen. For plans with a nominal energy of 215 MeV the pass rate was 99.8% for 1%/1mm between the two gantry angles. Conclusion: Differences in beam sigma of up to 7.8% do not cause significant differences in the dose distribution of different spot size gammas.« less

Long range ordered alloys modified by addition of niobium and cerium

DOEpatents

Liu, C.T.

1984-08-22

Long range ordered alloys are described having the nominal composition (Fe,Ni,Co)/sub 3/ (V,M) where M is a ductility enhancing metal selected from the group Ti, Zr, Hf with additions of small amounts of cerium and niobium to dramatically enhance the creep properties of the resulting alloys.

Long range ordered alloys modified by addition of niobium and cerium

DOEpatents

Liu, Chain T.

1987-01-01

Long range ordered alloys are described having the nominal composition (Fe,Ni,Co).sub.3 (V,M) where M is a ductility enhancing metal selected from the group Ti, Zr, Hf with additions of small amounts of cerium and niobium to drammatically enhance the creep properties of the resulting alloys.

DOE Office of Scientific and Technical Information (OSTI.GOV)

Zhang, Yingchen; Tan, Jin; Krad, Ibrahim

Power system frequency needs to be maintained close to its nominal value at all times to successfully balance load and generation and maintain system reliability. Adequate primary frequency response and secondary frequency response are the primary forces to correct an energy imbalance at the second-to-minute level. As wind energy becomes a larger portion of the world's energy portfolio, there is an increased need for wind to provide frequency response. This paper addresses one of the major concerns about using wind for frequency regulation: the unknown factor of the interaction between primary and secondary reserves. The lack of a commercially availablemore » tool to model this has limited the energy industry's understanding of when the depletion of primary reserves will impact the performance of secondary response or vice versa. This paper investigates the issue by developing a multi-area frequency response integration tool with combined primary and secondary capabilities. The simulation is conducted in close coordination with economical energy scheduling scenarios to ensure credible simulation results.« less

Orbital Signature Analyzer (OSA): A spacecraft health/safety monitoring and analysis tool

NASA Technical Reports Server (NTRS)

Weaver, Steven; Degeorges, Charles; Bush, Joy; Shendock, Robert; Mandl, Daniel

1993-01-01

Fixed or static limit sensing is employed in control centers to ensure that spacecraft parameters remain within a nominal range. However, many critical parameters, such as power system telemetry, are time-varying and, as such, their 'nominal' range is necessarily time-varying as well. Predicted data, manual limits checking, and widened limit-checking ranges are often employed in an attempt to monitor these parameters without generating excessive limits violations. Generating predicted data and manual limits checking are both resource intensive, while broadening limit ranges for time-varying parameters is clearly inadequate to detect all but catastrophic problems. OSA provides a low-cost solution by using analytically selected data as a reference upon which to base its limits. These limits are always defined relative to the time-varying reference data, rather than as fixed upper and lower limits. In effect, OSA provides individual limits tailored to each value throughout all the data. A side benefit of using relative limits is that they automatically adjust to new reference data. In addition, OSA provides a wealth of analytical by-products in its execution.

Experimental characterization of the perceptron laser rangefinder

NASA Technical Reports Server (NTRS)

Kweon, I. S.; Hoffman, Regis; Krotkov, Eric

1991-01-01

In this report, we characterize experimentally a scanning laser rangefinder that employs active sensing to acquire three-dimensional images. We present experimental techniques applicable to a wide variety of laser scanners, and document the results of applying them to a device manufactured by Perceptron. Nominally, the sensor acquires data over a 60 deg x 60 deg field of view in 256 x 256 pixel images at 2 Hz. It digitizes both range and reflectance pixels to 12 bits, providing a maximum range of 40 m and a depth resolution of 1 cm. We present methods and results from experiments to measure geometric parameters including the field of view, angular scanning increments, and minimum sensing distance. We characterize qualitatively problems caused by implementation flaws, including internal reflections and range drift over time, and problems caused by inherent limitations of the rangefinding technology, including sensitivity to ambient light and surface material. We characterize statistically the precision and accuracy of the range measurements. We conclude that the performance of the Perceptron scanner does not compare favorably with the nominal performance, that scanner modifications are required, and that further experimentation must be conducted.

Development of rotating magnetic field coil system in the HIST spherical torus device

NASA Astrophysics Data System (ADS)

Yoshikawa, T.; Kikuchi, Y.; Yamada, S.; Hashimoto, S.; Nishioka, T.; Fukumoto, N.; Nagata, M.

2007-11-01

Coaxial Helicity Injection (CHI) is one of most attractive methods to achieve non-inductive current drive in spherical torus devices. The current drive mechanism of CHI relies on MHD relaxation process of rotating kink behavior [1], so that there is a possibility to control the CHI by using an externally applied rotating magnetic field (RMF). We have recently started to develop a RMF coil system in the HIST spherical torus device. Eight coils are located above and below the midplane at four toroidal locations so that the RMF is resonant with n = 1 rotating kink mode driven by the CHI. In addition, the RMF coil set is installed inside a flux conserver of 5 mm thickness (cut-off frequency ˜ 170 Hz) so that the RMF penetrates into the plasma. The coil winding is made of 20 turns of enameled copper circular wires (1.5 mm^2 conductor cross section), covered with a thin stainless steal case of 0.5 mm thickness (cut-off frequency ˜ 710 kHz). The RMF system is driven by an IGBT inverter power supply (nominal current: 1 kA, nominal voltage: 1 kV) with an operating frequency band from 10 kHz to 30 kHz. The estimated amplitude of RMF neglecting effects of image current at the flux conserver is a few tens Gauss at around the magnetic axis. A preliminary experimental result will be shown in the conference. [1] M. Nagata, et al., Physics of Plasmas 10, 2932 (2003).

Venus radar mapper attitude reference quaternion

NASA Technical Reports Server (NTRS)

Lyons, D. T.

1986-01-01

Polynomial functions of time are used to specify the components of the quaternion which represents the nominal attitude of the Venus Radar mapper spacecraft during mapping. The following constraints must be satisfied in order to obtain acceptable synthetic array radar data: the nominal attitude function must have a large dynamic range, the sensor orientation must be known very accurately, the attitude reference function must use as little memory as possible, and the spacecraft must operate autonomously. Fitting polynomials to the components of the desired quaternion function is a straightforward method for providing a very dynamic nominal attitude using a minimum amount of on-board computer resources. Although the attitude from the polynomials may not be exactly the one requested by the radar designers, the polynomial coefficients are known, so they do not contribute to the attitude uncertainty. Frequent coefficient updates are not required, so the spacecraft can operate autonomously.

Membership nominations in international scientific assessments

NASA Astrophysics Data System (ADS)

Leifeld, Philip; Fisher, Dana R.

2017-10-01

International scientific assessments are transnational knowledge-based expert networks with a mandate to advise policymakers. A well-known example is the Millennium Ecosystem Assessment (MA), which synthesized research on ecosystem services between 2001 and 2005, utilizing the knowledge of 1,360 expert members. Little, however, is known about the membership composition and the driving forces behind membership nominations in the MA and similar organizations. Here we introduce a survey data set on recruitment in the MA and analyse nomination patterns among experts as a complex network. The results indicate that membership recruitment was governed by prior contacts in other transnational elite organizations and a range of other factors related to personal affinity. Network analysis demonstrates how some core individuals were particularly influential in shaping the overall membership composition of the group. These findings add to recently noted concerns about the lack of diversity of views represented in international scientific assessments.

Orbit Determination Error Analysis Results for the Triana Sun-Earth L2 Libration Point Mission

NASA Technical Reports Server (NTRS)

Marr, G.

2003-01-01

Using the NASA Goddard Space Flight Center's Orbit Determination Error Analysis System (ODEAS), orbit determination error analysis results are presented for all phases of the Triana Sun-Earth L1 libration point mission and for the science data collection phase of a future Sun-Earth L2 libration point mission. The Triana spacecraft was nominally to be released by the Space Shuttle in a low Earth orbit, and this analysis focuses on that scenario. From the release orbit a transfer trajectory insertion (TTI) maneuver performed using a solid stage would increase the velocity be approximately 3.1 km/sec sending Triana on a direct trajectory to its mission orbit. The Triana mission orbit is a Sun-Earth L1 Lissajous orbit with a Sun-Earth-vehicle (SEV) angle between 4.0 and 15.0 degrees, which would be achieved after a Lissajous orbit insertion (LOI) maneuver at approximately launch plus 6 months. Because Triana was to be launched by the Space Shuttle, TTI could potentially occur over a 16 orbit range from low Earth orbit. This analysis was performed assuming TTI was performed from a low Earth orbit with an inclination of 28.5 degrees and assuming support from a combination of three Deep Space Network (DSN) stations, Goldstone, Canberra, and Madrid and four commercial Universal Space Network (USN) stations, Alaska, Hawaii, Perth, and Santiago. These ground stations would provide coherent two-way range and range rate tracking data usable for orbit determination. Larger range and range rate errors were assumed for the USN stations. Nominally, DSN support would end at TTI+144 hours assuming there were no USN problems. Post-TTI coverage for a range of TTI longitudes for a given nominal trajectory case were analyzed. The orbit determination error analysis after the first correction maneuver would be generally applicable to any libration point mission utilizing a direct trajectory.

Modeling and evaluation of a high-resolution CMOS detector for cone-beam CT of the extremities.

PubMed

Cao, Qian; Sisniega, Alejandro; Brehler, Michael; Stayman, J Webster; Yorkston, John; Siewerdsen, Jeffrey H; Zbijewski, Wojciech

2018-01-01

Quantitative assessment of trabecular bone microarchitecture in extremity cone-beam CT (CBCT) would benefit from the high spatial resolution, low electronic noise, and fast scan time provided by complementary metal-oxide semiconductor (CMOS) x-ray detectors. We investigate the performance of CMOS sensors in extremity CBCT, in particular with respect to potential advantages of thin (<0.7 mm) scintillators offering higher spatial resolution. A cascaded systems model of a CMOS x-ray detector incorporating the effects of CsI:Tl scintillator thickness was developed. Simulation studies were performed using nominal extremity CBCT acquisition protocols (90 kVp, 0.126 mAs/projection). A range of scintillator thickness (0.35-0.75 mm), pixel size (0.05-0.4 mm), focal spot size (0.05-0.7 mm), magnification (1.1-2.1), and dose (15-40 mGy) was considered. The detectability index was evaluated for both CMOS and a-Si:H flat-panel detector (FPD) configurations for a range of imaging tasks emphasizing spatial frequencies associated with feature size aobj. Experimental validation was performed on a CBCT test bench in the geometry of a compact orthopedic CBCT system (SAD = 43.1 cm, SDD = 56.0 cm, matching that of the Carestream OnSight 3D system). The test-bench studies involved a 0.3 mm focal spot x-ray source and two CMOS detectors (Dalsa Xineos-3030HR, 0.099 mm pixel pitch) - one with the standard CsI:Tl thickness of 0.7 mm (C700) and one with a custom 0.4 mm thick scintillator (C400). Measurements of modulation transfer function (MTF), detective quantum efficiency (DQE), and CBCT scans of a cadaveric knee (15 mGy) were obtained for each detector. Optimal detectability for high-frequency tasks (feature size of ~0.06 mm, consistent with the size of trabeculae) was ~4× for the C700 CMOS detector compared to the a-Si:H FPD at nominal system geometry of extremity CBCT. This is due to ~5× lower electronic noise of a CMOS sensor, which enables input quantum-limited imaging at smaller pixel size. Optimal pixel size for high-frequency tasks was <0.1 mm for a CMOS, compared to ~0.14 mm for an a-Si:H FPD. For this fine pixel pitch, detectability of fine features could be improved by using a thinner scintillator to reduce light spread blur. A 22% increase in detectability of 0.06 mm features was found for the C400 configuration compared to C700. An improvement in the frequency at 50% modulation (f 50 ) of MTF was measured, increasing from 1.8 lp/mm for C700 to 2.5 lp/mm for C400. The C400 configuration also achieved equivalent or better DQE as C700 for frequencies above ~2 mm -1 . Images of cadaver specimens confirmed improved visualization of trabeculae with the C400 sensor. The small pixel size of CMOS detectors yields improved performance in high-resolution extremity CBCT compared to a-Si:H FPDs, particularly when coupled with a custom 0.4 mm thick scintillator. The results indicate that adoption of a CMOS detector in extremity CBCT can benefit applications in quantitative imaging of trabecular microstructure in humans. © 2017 American Association of Physicists in Medicine.

Identification of cascade water tanks using a PWARX model

NASA Astrophysics Data System (ADS)

Mattsson, Per; Zachariah, Dave; Stoica, Petre

2018-06-01

In this paper we consider the identification of a discrete-time nonlinear dynamical model for a cascade water tank process. The proposed method starts with a nominal linear dynamical model of the system, and proceeds to model its prediction errors using a model that is piecewise affine in the data. As data is observed, the nominal model is refined into a piecewise ARX model which can capture a wide range of nonlinearities, such as the saturation in the cascade tanks. The proposed method uses a likelihood-based methodology which adaptively penalizes model complexity and directly leads to a computationally efficient implementation.

Polyurethane Foam Impact Experiments and Simulations

NASA Astrophysics Data System (ADS)

Kipp, M. E.; Chhabildas, L. C.; Reinhart, W. D.; Wong, M. K.

1999-06-01

Uniaxial strain impact experiments with a rigid polyurethane foam of nominal density 0.22g/cc are reported. A 6 mm thick foam impactor is mounted on the face of a projectile and impacts a thin (1 mm) target plate of aluminum or copper, on which the rear free surface velocity history is acquired with a VISAR. Impact velocities ranged from 300 to 1500 m/s. The velocity record monitors the initial shock from the foam transmitted through the target, followed by a reverberation within the target plate as the wave interacts with the compressed foam at the impact interface and the free recording surface. These one-dimensional uniaxial strain impact experiments were modeled using a traditional p-alpha porous material model for the distended polyurethane, which generally captured the motion imparted to the target by the foam. Some of the high frequency aspects of the data, reflecting the heterogeneous nature of the foam, can be recovered with computations of fully 3-dimensional explicit representations of this porous material.

Multiferroics BiMn1-xAlxO3 nanoparticles: Synthesis, characterization and evaluation of various structural, physical, electrical and dielectric parameters

NASA Astrophysics Data System (ADS)

Ahmad, Bashir; Raissat, Rabia; Mumtaz, Saleem; Ahmad, Zahoor; Sadiq, Imran; Ashiq, Muhammad Naeem; Najam-ul-Haq, Muhammad

2017-07-01

The aluminium substituted bismuth based manganates with nominal composition BiMn1-xAlxO3 (x = 0.0, 0.2, 0.4, 0.6 and 0.8) were prepared by the simple microemulsion method. The alteration in their structural, electrical and dielectric parameters due to Al substitution has been investigated. The X-ray diffraction analysis (XRD) confirms the formation of single phase orthorhombic with crystallite size ranges from 32 to 52 nm. The morphological features and particle size were determined by using scanning electron microscopy (SEM). The dc electrical resistivity increased from 6 × 108 to 8 × 109 Ω cm with the increase in substituent concentration. The dielectric constant, dielectric loss tangent and dielectric loss factor decreased with the increase in frequency. The increase in electrical resistivity makes the synthesized materials paramount over other materials and can be useful for technological applications in microwave devices.

ELF-VLF communications through the Earth Project report for calendar year 1984, revision 1

NASA Astrophysics Data System (ADS)

Buettner, H. M.; Burker, G. J.; Didwall, E. M.; Holladay, G.; Lytle, R. J.

1985-08-01

We use computer models and experiments to explore the feasibility of communication between points underground and on the Earth's surface. Emphasis is placed on ELF-VLF electromagnetic propagation through the Earth; nominally, we investigated propagation in the 200 Hz-30 kHz frequency range. The computer modeling included calculations of the fields of a point electric or magnetic source in a homogeneous half space or a stratified earth. Initial results for an insulated antenna of finite length are also considered. The experiments involved through-the-Earth transmissions at two locations in Pennsylvania, both of which had large formations of limestone. Initial results indicate that information rates as high as kbits/s may be possible for subsurface depths of 300 m or less. Accuracy of these estimates depends on the electromagnetic propagation constant of the rock, the noise characteristics, and the modulation scheme. Although a nuisance for evaluating through-the-Earth propagation, the existence of subsurface metal conductors can improve the transmission character of the site.

ELF-VLF communications through-the-Earth

NASA Astrophysics Data System (ADS)

Buettner, H. M.; Burke, G. J.; Didwall, E. M.; Holladay, G.; Lytle, R. J.

1985-06-01

We use computer models and experiments to explore the feasibility of communication between points underground and on the Earth's surface. Emphasis is placed on ELF-VLF electromagnetic propagation through the Earth; nominally, we investigated propagation in the 200 Hz-30 kHz frequency range. The computer modeling included calculations of the fields of a point electric or magnetic source in a homogeneous half space or a stratified Earth. Initial results for an insulated antenna of finite length are also considered. The experiments involved through-the-Earth transmissions at two locations in Pennsylvania, both of which had large formations of limestone. Initial results indicate that information rates as high as kbits/s may be possible for subsurface depths of 300 m or less. Accuracy of these estimates depends on the electromagnetic propagation constants of the rock, the noise characteristics, and modulation scheme. Although a nuisance for evaluating through-the-Earth propagation, the existence of subsurface metal conductors can improve the transmission character of the site.

High-Fidelity Multi-Rotor Unmanned Aircraft System Simulation Development for Trajectory Prediction Under Off-Nominal Flight Dynamics

NASA Technical Reports Server (NTRS)

Foster, John V.; Hartman, David C.

2017-01-01

The NASA Unmanned Aircraft System (UAS) Traffic Management (UTM) project is conducting research to enable civilian low-altitude airspace and UAS operations. A goal of this project is to develop probabilistic methods to quantify risk during failures and off nominal flight conditions. An important part of this effort is the reliable prediction of feasible trajectories during off-nominal events such as control failure, atmospheric upsets, or navigation anomalies that can cause large deviations from the intended flight path or extreme vehicle upsets beyond the normal flight envelope. Few examples of high-fidelity modeling and prediction of off-nominal behavior for small UAS (sUAS) vehicles exist, and modeling requirements for accurately predicting flight dynamics for out-of-envelope or failure conditions are essentially undefined. In addition, the broad range of sUAS aircraft configurations already being fielded presents a significant modeling challenge, as these vehicles are often very different from one another and are likely to possess dramatically different flight dynamics and resultant trajectories and may require different modeling approaches to capture off-nominal behavior. NASA has undertaken an extensive research effort to define sUAS flight dynamics modeling requirements and develop preliminary high fidelity six degree-of-freedom (6-DOF) simulations capable of more closely predicting off-nominal flight dynamics and trajectories. This research has included a literature review of existing sUAS modeling and simulation work as well as development of experimental testing methods to measure and model key components of propulsion, airframe and control characteristics. The ultimate objective of these efforts is to develop tools to support UTM risk analyses and for the real-time prediction of off-nominal trajectories for use in the UTM Risk Assessment Framework (URAF). This paper focuses on modeling and simulation efforts for a generic quad-rotor configuration typical of many commercial vehicles in use today. An overview of relevant off-nominal multi-rotor behaviors will be presented to define modeling goals and to identify the prediction capability lacking in simplified models of multi-rotor performance. A description of recent NASA wind tunnel testing of multi-rotor propulsion and airframe components will be presented illustrating important experimental and data acquisition methods, and a description of preliminary propulsion and airframe models will be presented. Lastly, examples of predicted off-nominal flight dynamics and trajectories from the simulation will be presented.

MO-F-CAMPUS-T-03: Verification of Range, SOBP Width, and Output for Passive-Scattering Proton Beams Using a Liquid Scintillator Detector

DOE Office of Scientific and Technical Information (OSTI.GOV)

Henry, T; Robertson, D; Therriault-Proulx, F

2015-06-15

Purpose: Liquid scintillators have been shown to provide fast and high-resolution measurements of radiation beams. However, their linear energy transfer-dependent response (quenching) limits their use in proton beams. The purpose of this study was to develop a simple and fast method to verify the range, spread-out Bragg peak (SOBP) width, and output of a passive-scattering proton beam with a liquid scintillator detector, without the need for quenching correction. Methods: The light signal from a 20×20×20 cm3 liquid scintillator tank was collected with a CCD camera. Reproducible landmarks on the SOBP depth-light curve were identified which possessed a linear relationship withmore » the beam range and SOBP width. The depth-light profiles for three beam energies (140, 160 and 180 MeV) with six SOBP widths at each energy were measured with the detector. Beam range and SOBP width calibration factors were obtained by comparing the depth-light curve landmarks with the nominal range and SOBP width for each beam setting. The daily output stability of the liquid scintillator detector was also studied by making eight repeated output measurements in a cobalt-60 beam over the course of two weeks. Results: The mean difference between the measured and nominal beam ranges was 0.6 mm (σ=0.2 mm), with a maximum difference of 0.9 mm. The mean difference between the measured and nominal SOBP widths was 0.1 mm (σ=1.8 mm), with a maximum difference of 4.0 mm. Finally an output variation of 0.14% was observed for 8 measurements performed over 2 weeks. Conclusion: A method has been developed to determine the range and SOBP width of a passive-scattering proton beam in a liquid scintillator without the need for quenching correction. In addition to providing rapid and accurate beam range and SOBP measurements, the detector is capable of measuring the output consistency with a high degree of precision. This project was supported in part by award number CA182450 from the National Cancer Institute.« less

Identifying future models for delivering genetic services: a nominal group study in primary care

PubMed Central

Elwyn, Glyn; Edwards, Adrian; Iredale, Rachel; Davies, Peter; Gray, Jonathon

2005-01-01

Background To enable primary care medical practitioners to generate a range of possible service delivery models for genetic counselling services and critically assess their suitability. Methods Modified nominal group technique using in primary care professional development workshops. Results 37 general practitioners in Wales, United Kingdom too part in the nominal group process. The practitioners who attended did not believe current systems were sufficient to meet anticipated demand for genetic services. A wide range of different service models was proposed, although no single option emerged as a clear preference. No argument was put forward for genetic assessment and counselling being central to family practice, neither was there a voice for the view that the family doctor should become skilled at advising patients about predictive genetic testing and be able to counsel patients about the wider implications of genetic testing for patients and their family members, even for areas such as common cancers. Nevertheless, all the preferred models put a high priority on providing the service in the community, and often co-located in primary care, by clinicians who had developed expertise. Conclusion There is a need for a wider debate about how healthcare systems address individual concerns about genetic concerns and risk, especially given the increasing commercial marketing of genetic tests. PMID:15831099

Harmonic mode-locking using the double interval technique in quantum dot lasers.

PubMed

Li, Yan; Chiragh, Furqan L; Xin, Yong-Chun; Lin, Chang-Yi; Kim, Junghoon; Christodoulou, Christos G; Lester, Luke F

2010-07-05

Passive harmonic mode-locking in a quantum dot laser is realized using the double interval technique, which uses two separate absorbers to stimulate a specific higher-order repetition rate compared to the fundamental. Operating alone these absorbers would otherwise reinforce lower harmonic frequencies, but by operating together they produce the harmonic corresponding to their least common multiple. Mode-locking at a nominal 60 GHz repetition rate, which is the 10(th) harmonic of the fundamental frequency of the device, is achieved unambiguously despite the constraint of a uniformly-segmented, multi-section device layout. The diversity of repetition rates available with this method is also discussed.

Observation of superradiant synchrotron radiation in the terahertz region

NASA Astrophysics Data System (ADS)

Billinghurst, B. E.; Bergstrom, J. C.; Dallin, L.; de Jong, M.; May, T. E.; Vogt, J. M.; Wurtz, W. A.

2013-06-01

We report the first high-resolution measurement of superradiance, using coherent synchrotron radiation in the terahertz region from the Canadian Light Source synchrotron and a Michelson interferometer with a nominal frequency resolution of 0.00096cm-1. Superradiance arises when a high degree of phase coherence exists between the radiation fields of the individual electron bunches, and manifests itself as a series of narrow spectral peaks at harmonics of the bunch frequency. We observe an enhancement factor of 16 at the spectral peaks, limited by the interferometer resolution. The spectral distribution and relative amplitudes of the superradiant peaks are modified by altering the pattern of bunches along the bunch train.

A Statistical Analysis of Langmuir Wave-Electron Correlations Observed by the CHARM II Auroral Sounding Rocket

NASA Astrophysics Data System (ADS)

Dombrowski, M. P.; Labelle, J. W.; Kletzing, C.; Bounds, S. R.; Kaeppler, S. R.

2014-12-01

Langmuir-mode electron plasma waves are frequently observed by spacecraft in active plasma environments such as the ionosphere. Ionospheric Langmuir waves may be excited by the bump-on-tail instability generated by impinging beams of electrons traveling parallel to the background magnetic field (B). The Correlation of High-frequencies and Auroral Roar Measurement (CHARM II) sounding rocket was launched into a substorm at 9:49 UT on 17 February 2010, from the Poker Flat Research Range in Alaska. The primary instruments included the University of Iowa Wave-Particle Correlator (WPC), the Dartmouth High-Frequency Experiment (HFE), several charged particle detectors, low-frequency wave instruments, and a magnetometer. The HFE is a receiver system which effectively yields continuous (100% duty cycle) electric-field waveform measurements from 100 kHz to 5 MHz, and which had its detection axis aligned nominally parallel to B. The HFE output was fed on-payload to the WPC, which uses a phase-locked loop to track the incoming wave frequency with the most power, then sorting incoming electrons at eight energy levels into sixteen wave-phase bins. CHARM II encountered several regions of strong Langmuir wave activity throughout its 15-minute flight, and the WPC showed wave-lock and statistically significant particle correlation distributions during several time periods. We show results of an in-depth analysis of the CHARM II WPC data for the entire flight, including statistical analysis of correlations which show evidence of direct interaction with the Langmuir waves, indicating (at various times) trapping of particles and both driving and damping of Langmuir waves by particles. In particular, the sign of the gradient in particle flux appears to correlate with the phase relation between the electrons and the wave field, with possible implications for the wave physics.

Underexpanded Screeching Jets From Circular, Rectangular, and Elliptic Nozzles

NASA Technical Reports Server (NTRS)

Panda, J.; Raman, G.; Zaman, K. B. M. Q.

2004-01-01

The screech frequency and amplitude, the shock spacing, the hydrodynamic-acoustic standing wave spacing, and the convective velocity of large organized structures are measured in the nominal Mach number range of 1.1 less than or = Mj less that or = l0.9 for supersonic, underexpanded jets exhausting from a circular, a rectangular and an elliptic nozzle. This provides a carefully measured data set useful in comparing the importance of various physical parameters in the screech generation process. The hydrodynamic-acoustic standing wave is formed between the potential pressure field of large turbulent structures and the acoustic pressure field of the screech sound. It has been demonstrated earlier that in the currently available screech frequency prediction models replacement of the shock spacing by the standing wave spacing provides an exact expression. In view of this newly found evidence, a comparison is made between the average standing wavelength and the average shock spacing. It is found that there exists a small, yet important, difference, which is dependent on the azimuthal screech mode. For example, in the flapping modes of circular, rectangular, and elliptic jets, the standing wavelength is slightly longer than the shock spacing, while for the helical screech mode in a circular jet the opposite is true. This difference accounts for the departure of the existing models from predicting the exact screech frequency. Another important parameter, necessary in screech prediction, is the convective velocity of the large organized structures. It is demonstrated that the presence of the hydrodynamic-acoustic standing wave, even inside the jet shear layer, becomes a significant source of error in the convective velocity data obtained using the conventional methods. However, a new relationship, using the standing wavelength and screech frequency is shown to provide more accurate results.

Effect of proof testing on the flaw growth characteristics of 304 stainless steel. [crack propagation in welded joints

NASA Technical Reports Server (NTRS)

Finger, R. W.

1974-01-01

The effects of proof overload frequency and magnitude on the cyclic crack growth rates of 304 stainless steel weldments were investigated. The welding procedure employed was typical of those used on over-the-road cryogenic vessels. Tests were conducted at room temperature with an overload ratio of 1.50 to determine the effect of overload frequency. Effect of overload magnitude was determined from tests where a room temperature overload was applied between blocks of 1000 cycles applied at 78 K (-320 F). The cyclic stress level used in all tests was typical of the nominal membrane stress generally encountered in full scale vessels. Test results indicate that judicious selection of proof overload frequency and magnitude can reduce crack growth rates for cyclic stress levels.

Enhanced ferromagnetic resonance linewidth of the free layer in perpendicular magnetic tunnel junctions

NASA Astrophysics Data System (ADS)

Gopman, D. B.; Dennis, C. L.; McMichael, R. D.; Hao, X.; Wang, Z.; Wang, X.; Gan, H.; Zhou, Y.; Zhang, J.; Huai, Y.

2017-05-01

We report the frequency dependence of the ferromagnetic resonance linewidth of the free layer in magnetic tunnel junctions with all perpendicular-to-the-plane magnetized layers. While the magnetic-field-swept linewidth nominally shows a linear growth with frequency in agreement with Gilbert damping, an additional frequency-dependent linewidth broadening occurs that shows a strong asymmetry between the absorption spectra for increasing and decreasing external magnetic field. Inhomogeneous magnetic fields produced during reversal of the reference and pinned layer complex is demonstrated to be at the origin of the symmetry breaking and the linewidth enhancement. Consequentially, this linewidth enhancement provides indirect information on the magnetic coercivity of the reference and pinned layers. These results have important implications for the characterization of perpendicular magnetized magnetic random access memory bit cells.

NGS Nominated CELA1, HSPG2, and KCNK5 as Candidate Genes for Predisposition to Balkan Endemic Nephropathy

PubMed Central

Toncheva, D.; Mihailova-Hristova, M.; Vazharova, R.; Staneva, R.; Karachanak, S.; Dimitrov, P.; Simeonov, V.; Ivanov, S.; Balabanski, L.; Serbezov, D.; Malinov, M.; Stefanovic, V.; Čukuranović, R.; Polenakovic, M.; Jankovic-Velickovic, L.; Djordjevic, V.; Jevtovic-Stoimenov, T.; Plaseska-Karanfilska, D.; Galabov, A.; Djonov, V.; Dimova, I.

2014-01-01

Balkan endemic nephropathy (BEN) is a familial chronic tubulointerstitial disease with insidious onset and slow progression leading to terminal renal failure. The results of molecular biological investigations propose that BEN is a multifactorial disease with genetic predisposition to environmental risk agents. Exome sequencing of 22 000 genes with Illumina Nextera Exome Enrichment Kit was performed on 22 DNA samples (11 Bulgarian patients and 11 Serbian patients). Software analysis was performed via NextGene, Provean, and PolyPhen. The frequency of all annotated genetic variants with deleterious/damaging effect was compared with those of European populations. Then we focused on nonannotated variants (with no data available about them and not found in healthy Bulgarian controls). There is no statistically significant difference between annotated variants in BEN patients and European populations. From nonannotated variants with more than 40% frequency in both patients' groups, we nominated 3 genes with possible deleterious/damaging variants—CELA1, HSPG2, and KCNK5. Mutant genes (CELA1, HSPG2, and KCNK5) in BEN patients encode proteins involved in basement membrane/extracellular matrix and vascular tone, tightly connected to process of angiogenesis. We suggest that an abnormal process of angiogenesis plays a key role in the molecular pathogenesis of BEN. PMID:24949484

[Phenotypic variability of the shell in Neritinidae (Gastropoda: Neritimorpha) in Puerto Rican rivers].

PubMed

Blanco, Juan Felipe; Tamayo, Silvana; Scatena, Frederick N

2014-04-01

Gastropods of the Neritinidae family exhibit an amphidromous life cycle and an impressive variability in shell coloration in Puerto Rican streams and rivers. Various nominal species have been described, but Neritina virginea [Linne 1758], N. punctulata [Lamarck 1816] and N. reclivata [Say 1822] are the only broadly reported. However, recent studies have shown that these three species are sympatric at the river scale and that species determination might be difficult due to the presence of intermediate color morphs. Individuals (8 751) were collected from ten rivers across Puerto Rico, and from various segments and habitats in Mameyes River (the most pristine island-wide) during three years (2000-2003), and they were assigned to one of seven phenotypes corresponding to nominal species and morphs (non-nominal species). The "axial lines and dots" morph corresponding to N. reclivata was the most frequent island-wide, while the patelliform N. punctulata was scant, but the only found in headwater reaches. The "yellowish large tongues" phenotype, typical of N. virginea s.s. was the most frequent in the river mouth. The frequency of secondary phenotypes varied broadly among rivers, along the rivers, and among habitats, seemly influenced by salinity and predation gradients. The occurrence of individuals with coloration shifts after predation injuries, suggests phenotypic plasticity in the three nominal species, and urges for the use of molecular markers to unravel the possible occurrence of a species complex, and to understand the genetic basis of polymorphism. The longitudinal distribution of individual sizes, population density and egg capsules suggested the adaptive value of upstream migration, possibly to avoid marine predators.

The Production of Nominal and Verbal Inflection in an Agglutinative Language: Evidence from Hungarian

PubMed Central

Peckham, Don; Szanka, Szilvia; Gazso, Dorottya; Lovassy, Noemi; Ullman, Michael T.

2015-01-01

The contrast between regular and irregular inflectional morphology has been useful in investigating the functional and neural architecture of language. However, most studies have examined the regular/irregular distinction in non-agglutinative Indo-European languages (primarily English) with relatively simple morphology. Additionally, the majority of research has focused on verbal rather than nominal inflectional morphology. The present study attempts to address these gaps by introducing both plural and past tense production tasks in Hungarian, an agglutinative non-Indo-European language with complex morphology. Here we report results on these tasks from healthy Hungarian native-speaking adults, in whom we examine regular and irregular nominal and verbal inflection in a within-subjects design. Regular and irregular nouns and verbs were stem on frequency, word length, and phonological structure, and both accuracy and response times were acquired. The results revealed that the regular/irregular contrast yields similar patterns in Hungarian, for both nominal and verbal inflection, as in previous studies of non-agglutinative Indo-European languages: the production of irregular inflected forms was both less accurate and slower than of regular forms, both for plural and past-tense inflection. The results replicate and extend previous findings to an agglutinative language with complex morphology. Together with previous studies, the evidence suggests that the regular/irregular distinction yields a basic behavioral pattern that holds across language families and linguistic typologies. Finally, the study sets the stage for further research examining the neurocognitive substrates of regular and irregular morphology in an agglutinative non-Indo-European language. PMID:25769039

The Absolute Vector Magnetometers on Board Swarm, Lessons Learned From Two Years in Space.

NASA Astrophysics Data System (ADS)

Hulot, G.; Leger, J. M.; Vigneron, P.; Brocco, L.; Olsen, N.; Jager, T.; Bertrand, F.; Fratter, I.; Sirol, O.; Lalanne, X.

2015-12-01

ESA's Swarm satellites carry 4He absolute magnetometers (ASM), designed by CEA-Léti and developed in partnership with CNES. These instruments are the first-ever space-born magnetometers to use a common sensor to simultaneously deliver 1Hz independent absolute scalar and vector readings of the magnetic field. They have provided the very high accuracy scalar field data nominally required by the mission (for both science and calibration purposes, since each satellite also carries a low noise high frequency fluxgate magnetometer designed by DTU), but also very useful experimental absolute vector data. In this presentation, we will report on the status of the instruments, as well as on the various tests and investigations carried out using these experimental data since launch in November 2013. In particular, we will illustrate the advantages of flying ASM instruments on space-born magnetic missions for nominal data quality checks, geomagnetic field modeling and science objectives.

Motor torque compensation of an induction electric motor by adjusting a slip command during periods of supposed change in motor temperature

DOEpatents

Kelledes, William L.; St. John, Don K.

1992-01-01

The present invention maintains constant torque in an inverter driven AC induction motor during variations in rotor temperature. It is known that the torque output of a given AC induction motor is dependent upon rotor temperature. At rotor temperatures higher than the nominal operating condition the rotor impedance increases, reducing the rotor current and motor torque. In a similar fashion, the rotor impedance is reduced resulting in increased rotor current and motor torque when the rotor temperature is lower than the nominal operating condition. The present invention monitors the bus current from the DC supply to the inverter and adjusts the slip frequency of the inverter drive to maintain a constant motor torque. This adjustment is based upon whether predetermined conditions implying increased rotor temperature or decreased rotor temperature exist for longer that a predetermined interval of time.

Determining Exercise Strength Requirements for Astronaut Critical Mission Tasks: Reaching Under G-Load

NASA Technical Reports Server (NTRS)

Schaffner, Grant; Bentley, Jason

2008-01-01

The critical mission tasks assessments effort seeks to determine the physical performance requirements that astronauts must meet in order to safely and successfully accomplish lunar exploration missions. These assessments will determine astronaut preflight strength, fitness, and flexibility requirements, and the extent to which exercise and other countermeasures must prevent the physical deconditioning associated with prolonged weightlessness. The purpose is to determine the flexibility and strength that crewmembers must possess in order to reach Crew Exploration Vehicle controls during maneuvers that result in sustained acceleration levels ranging from 3.7G to 7.8G. An industry standard multibody dynamics application was used to create human models representing a 5th percentile female, a 50th percentile male, and a 95th percentile male. The additional mass of a space suit sleeve was added to the reaching arm to account for the influence of the suit mass on the reaching effort. The human model was merged with computer models of a pilot seat and control panel for the Crew Exploration Vehicle. Three dimensional paths were created that guided the human models hand from a starting position alongside its thigh to three control targets: a joystick, a keyboard, and an overhead switch panel. The reaching motion to each target was repeated under four vehicle acceleration conditions: nominal ascent (3.7G), two ascent aborts (5.5G and 7.8G) and lunar reentry (4.6G). Elbow and shoulder joint angular excursions were analyzed to assess range of motion requirements. Mean and peak elbow and shoulder joint torques were determined and converted to equivalent resistive exercise loads to assess strength requirements. Angular excursions for the 50th and 95th percentile male models remained within joint range of motion limits. For the 5th percentile female, both the elbow and the shoulder exceeded range of motion limits during the overhead reach. Elbow joint torques ranged from 10 N-m (nominal ascent) to 60 N-m (ascent abort). Shoulder joint torques ranged from 65 N-m (nominal ascent) to 280 N-m (ascent abort). Maximal equivalent exercise loads reached 30 lb in tricep extension, 9 lb in bicep curl, 110 lb in unilateral pullover and unilateral bench press for nominal conditions (lunar reentry), and 188 lb in unilateral pullover and unilateral bench press. The location of the pilot seat was found to be inadequately located to allow a 5th percentile female to reach the switches on the overhead panel. Elbow strength requirements were found to be well within population norms. Shoulder strength was found to be a limiting factor. Reaching under nominal ascent and lunar reentry conditions was found to require near maximal shoulder strength. Reaching under ascent abort conditions requires shoulder strength well beyond population norms. Pilot seats must adjust to accomodate a 5th percentile female. Exercise countermeasures must maintain maximal pullover and bench press strength to allow pilots to reach and operate controls during lunar reentry. Reaching will not be possible during ascent abort conditions. Flight controls should be built into armrests or flight control must be accomplished by autonomous systems during acceleration exceeding 4.6G.

Skin Friction at Very High Reynolds Numbers in the National Transonic Facility

NASA Technical Reports Server (NTRS)

Watson, Ralph D.; Anders, John B.; Hall, Robert M.

2006-01-01

Skin friction coefficients were derived from measurements using standard measurement technologies on an axisymmetric cylinder in the NASA Langley National Transonic Facility (NTF) at Mach numbers from 0.2 to 0.85. The pressure gradient was nominally zero, the wall temperature was nominally adiabatic, and the ratio of boundary layer thickness to model diameter within the measurement region was 0.10 to 0.14, varying with distance along the model. Reynolds numbers based on momentum thicknesses ranged from 37,000 to 605,000. The measurements approximately doubled the range of available data for flat plate skin friction coefficients. Three different techniques were used to measure surface shear. The maximum error of Preston tube measurements was estimated to be 2.5 percent, while that of Clauser derived measurements was estimated to be approximately 5 percent. Direct measurements by skin friction balance proved to be subject to large errors and were not considered reliable.

Magnetization measurements on multifilamentary No/sub 3/Sn and NbTi conductors

DOE Office of Scientific and Technical Information (OSTI.GOV)

Ghosh, A.K.; Robins, K.E.; Sampson, W.B.

1985-03-01

The effective filament size has been determined for a number of high current Nb/sub 3/Sn multifilamentary composites. In most cases it is much larger than the nominal filament size. For the smallest filaments (..integral.. 1 micron) the effective size can be as much as a factor of forty times the nominal size. Samples made by the ''internal tin'', ''bronze route'', and ''jelly roll'' methods have been examined with filaments in the range one to ten microns. Rate dependent magnetization and ''flux'' jumping'' have been observed in some cases. NbTi composites ranging in filament size from nine to two hundred micronsmore » and with copper to super-conductor ratios between 1.6:1 and 7:1 have been examined in the same apparatus. Low field ''flux jumping'' was only observed in conductors with very large filaments and relatively little stabilizing copper.« less

High-Efficiency Microwave Power Amplifier

NASA Technical Reports Server (NTRS)

Sims, Williams H.

2005-01-01

A high-efficiency power amplifier that operates in the S band (frequencies of the order of a few gigahertz) utilizes transistors operating under class-D bias and excitation conditions. Class-D operation has been utilized at lower frequencies, but, until now, has not been exploited in the S band. Nominally, in class D operation, a transistor is switched rapidly between "on" and "off" states so that at any given instant, it sustains either high current or high voltage, but not both at the same time. In the ideal case of zero "on" resistance, infinite "off" resistance, zero inductance and capacitance, and perfect switching, the output signal would be a perfect square wave. Relative to the traditional classes A, B, and C of amplifier operation, class D offers the potential to achieve greater power efficiency. In addition, relative to class-A amplifiers, class-D amplifiers are less likely to go into oscillation. In order to design this amplifier, it was necessary to derive mathematical models of microwave power transistors for incorporation into a larger mathematical model for computational simulation of the operation of a class-D microwave amplifier. The design incorporates state-of-the-art switching techniques applicable only in the microwave frequency range. Another major novel feature is a transmission-line power splitter/combiner designed with the help of phasing techniques to enable an approximation of a square-wave signal (which is inherently a wideband signal) to propagate through what would, if designed in a more traditional manner, behave as a more severely band-limited device (see figure). The amplifier includes an input, a driver, and a final stage. Each stage contains a pair of GaAs-based field-effect transistors biased in class D. The input signal can range from -10 to +10 dBm into a 50-ohm load. The table summarizes the performances of the three stages

Baseline Receiver Concept for a Next Generation Very Large Array

NASA Astrophysics Data System (ADS)

Srikanth, Sivasankaran; Wes Grammer, Silver Sturgis, Rob Selina

2018-01-01

The Next Generation Very Large Array (ngVLA) is envisioned to be an interferometric array with 10 times the effective collecting area and spatial resolution as the current VLA, operating over a frequency range of 1.2-116 GHz. Achieving these goals will require 214 antennas of nominal 18m diameter, on baselines of 300km. Maximizing sensitivity for each receiver band, while also minimizing the overall operating cost are the primary design goals. Therefore, receivers and feeds will be cryogenically cooled, with multiple bands integrated into a common cryostat to the greatest extent possible. Using feed designs that yield broad bandwidths and high aperture efficiencies are key to meeting these goals.The proposed receiver configuration will be implemented as six independent bands, each with its own feed. The upper five bands will be integrated into a single compact cryostat, while the lowest-frequency band occupies a second cryostat of similar volume and mass. The lowest-band feed is cooled to 80K, while all other feeds are cooled to 20K.For optimum performance at the higher frequencies, waveguide-bandwidth (~1.66:1) receivers are proposed to cover 12.6 – 50.5 GHz and 70 – 116 GHz in four separate bands, integrated into a single cryostat. Excellent LNA noise performance is readily achievable, and using waveguide throughout the signal chain reduces losses and their associated noise contributions, without adding undue size or weight. An axially-corrugated conical feed horn with wide flare angle (~50degree half-angle), based on a design by G. Cortes and L. Baker, is being considered for these receivers.For continuous coverage between 1.2 – 12.6 GHz, waveguide or even octave-bandwidth receivers are not cost-effective, given the > 10:1 frequency range. For these bands, wideband (3.25:1) receivers mated to a Caltech-designed quad-ridge feed horn (QRFH) are proposed. These feeds are highly compact, and cryogenically cooled to reduce losses ahead of the LNAs. Aperture efficiency and LNA noise temperature may be somewhat less than optimum: however, there would be significant cost savings by effectively halving the number of receivers and cryostats required per antenna.

FRB121102: First detection across 5 - 8 GHz and spectral properties from the Breakthrough Listen instrument

NASA Astrophysics Data System (ADS)

Gajjar, Vishal; Siemion, Andrew; MacMohan, David; Croft, Steve; Hellbourg, Greg; Isaacson, Howard; Enriquez, J. Emilio; Price, Daniel; Lebofsky, Matt; De Boer, David; Werthimer, Dan; Hickish, Jack; Brinkman, Casey; Chatterjee, Shami; Ransom, Scott M.; Law, Casey; Hessels, Jason W. T.; Cordes, Jim; Spitler, Laura; Lynch, Ryan; McLaughlin, Maura; Scholz, Paul; Marcote, Benito; Bower, Geoffrey C.; Tendulkar, Shriharsh

2018-01-01

Fast Radio Bursts (FRBs) are some of the most energetic and enigmatic events in the Universe. The origin of these sources is among the most challenging questions of modern-day astrophysics. Thus, it is imperative to understand the properties of these bursts across a range of radio frequencies. Among the known FRBs, FRB121102 is the only source known to show repeated bursts [Spitler et al., Nature, 531, 7593 202-205, 2016], which can allow a detailed investigation of various origin models. In August 2017, we initiated a campaign observing FRB 121102 using the Breakthrough Listen Digital Backend with the C-band receiver at the Robert C. Byrd Green Bank Telescope (GBT). We recorded baseband voltage data across 5.4 GHz of bandwidth, completely covering the C-band receiver's nominal 4-8 GHz band [MacMahon et al. arXiv:1707.06024v2]. The recorded data were searched for dispersed pulses consistent with the known dispersion measure of FRB 121102 (557 pc cm-3) using high-speed GPU software tools. We detected 21 bursts above our detection threshold of 6 sigmas in the first 60-minutes, out of which 18 occurred in the first 30-minutes only. To our knowledge, this is the highest event rate seen for FRB121102 at any observing frequency. These observations are the highest frequency and widest bandwidth detection of bursts from FRB 121102 (or any other FRB) obtained to-date. We note that individual bursts show marked changes in spectral extent ranging from hundreds of MHz to several GHz. We have used high frequency dynamic spectra of these bursts to estimate the characteristic scintillation bandwidth and correlation time-scale. We also found distinctive temporal structures, separated by a few milliseconds, in three of the strongest bursts, with each sub-structure exhibiting varied spectral features. We will discuss our findings and how these detections of FRB 121102 around 8 GHz opens up a new regime in scrutinizing various origin models. We will also highlight the unique capabilities of the Breakthrough Listen instrument at the GBT which allowed such sensitive and detailed observations.

Real-Time Load-Side Control of Electric Power Systems

NASA Astrophysics Data System (ADS)

Zhao, Changhong

Two trends are emerging from modern electric power systems: the growth of renewable (e.g., solar and wind) generation, and the integration of information technologies and advanced power electronics. The former introduces large, rapid, and random fluctuations in power supply, demand, frequency, and voltage, which become a major challenge for real-time operation of power systems. The latter creates a tremendous number of controllable intelligent endpoints such as smart buildings and appliances, electric vehicles, energy storage devices, and power electronic devices that can sense, compute, communicate, and actuate. Most of these endpoints are distributed on the load side of power systems, in contrast to traditional control resources such as centralized bulk generators. This thesis focuses on controlling power systems in real time, using these load side resources. Specifically, it studies two problems. (1) Distributed load-side frequency control: We establish a mathematical framework to design distributed frequency control algorithms for flexible electric loads. In this framework, we formulate a category of optimization problems, called optimal load control (OLC), to incorporate the goals of frequency control, such as balancing power supply and demand, restoring frequency to its nominal value, restoring inter-area power flows, etc., in a way that minimizes total disutility for the loads to participate in frequency control by deviating from their nominal power usage. By exploiting distributed algorithms to solve OLC and analyzing convergence of these algorithms, we design distributed load-side controllers and prove stability of closed-loop power systems governed by these controllers. This general framework is adapted and applied to different types of power systems described by different models, or to achieve different levels of control goals under different operation scenarios. We first consider a dynamically coherent power system which can be equivalently modeled with a single synchronous machine. We then extend our framework to a multi-machine power network, where we consider primary and secondary frequency controls, linear and nonlinear power flow models, and the interactions between generator dynamics and load control. (2) Two-timescale voltage control: The voltage of a power distribution system must be maintained closely around its nominal value in real time, even in the presence of highly volatile power supply or demand. For this purpose, we jointly control two types of reactive power sources: a capacitor operating at a slow timescale, and a power electronic device, such as a smart inverter or a D-STATCOM, operating at a fast timescale. Their control actions are solved from optimal power flow problems at two timescales. Specifically, the slow-timescale problem is a chance-constrained optimization, which minimizes power loss and regulates the voltage at the current time instant while limiting the probability of future voltage violations due to stochastic changes in power supply or demand. This control framework forms the basis of an optimal sizing problem, which determines the installation capacities of the control devices by minimizing the sum of power loss and capital cost. We develop computationally efficient heuristics to solve the optimal sizing problem and implement real-time control. Numerical experiments show that the proposed sizing and control schemes significantly improve the reliability of voltage control with a moderate increase in cost.

Validation of a particle tracking analysis method for the size determination of nano- and microparticles

NASA Astrophysics Data System (ADS)

Kestens, Vikram; Bozatzidis, Vassili; De Temmerman, Pieter-Jan; Ramaye, Yannic; Roebben, Gert

2017-08-01

Particle tracking analysis (PTA) is an emerging technique suitable for size analysis of particles with external dimensions in the nano- and sub-micrometre scale range. Only limited attempts have so far been made to investigate and quantify the performance of the PTA method for particle size analysis. This article presents the results of a validation study during which selected colloidal silica and polystyrene latex reference materials with particle sizes in the range of 20 nm to 200 nm were analysed with NS500 and LM10-HSBF NanoSight instruments and video analysis software NTA 2.3 and NTA 3.0. Key performance characteristics such as working range, linearity, limit of detection, limit of quantification, sensitivity, robustness, precision and trueness were examined according to recommendations proposed by EURACHEM. A model for measurement uncertainty estimation following the principles described in ISO/IEC Guide 98-3 was used for quantifying random and systematic variations. For nominal 50 nm and 100 nm polystyrene and a nominal 80 nm silica reference materials, the relative expanded measurement uncertainties for the three measurands of interest, being the mode, median and arithmetic mean of the number-weighted particle size distribution, varied from about 10% to 12%. For the nominal 50 nm polystyrene material, the relative expanded uncertainty of the arithmetic mean of the particle size distributions increased up to 18% which was due to the presence of agglomerates. Data analysis was performed with software NTA 2.3 and NTA 3.0. The latter showed to be superior in terms of sensitivity and resolution.

78 FR 44947 - Children's Health Protection Advisory Committee

Federal Register 2010, 2011, 2012, 2013, 2014

2013-07-25

... ENVIRONMENTAL PROTECTION AGENCY [FRL-9838-5] Children's Health Protection Advisory Committee AGENCY: Environmental Protection Agency (EPA). ACTION: Request for Nominations to the Children's Health... from a range of qualified candidates to be considered for appointment to its Children's Health...

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Federal Register 2010, 2011, 2012, 2013, 2014

2011-07-22

... Historic District, Buildings fronting Rodney Sq. at 10th, 11th, Market and King Sts., Wilmington IDAHO... MONTANA Missoula County Target Range Elementary School, 4095 South Ave., W., Missoula NEBRASKA Custer...

Final report on APMP.M.P-S3: Results of the supplementary comparison in gas media in the range 1.77 MPa to 6.8 MPa

NASA Astrophysics Data System (ADS)

Owen, N.; Bergoglio, M.

2013-01-01

This report provides the results of the supplementary bilateral comparison APMP.M.P-S3 between NMI Australia (NMIA) and INRIM, Italy executed from November 2010 to November 2011. NMIA acted as the pilot laboratory and provided a Ruska G series piston gauge as the transfer standard, with a nominal area 16.8 mm2 requiring a nominal load of 12 kg to balance a pressure of 7.0 MPa. The purpose of this supplementary bilateral comparison was to provide data for linking NMIA to CCM.P-K1.c in the pressure range greater than 4 MPa to extend the range covered by key comparison APMP.M.P-K1c. The original protocol called for the pressure range from 80 kPa to 6.80 MPa. Both participants agreed to limit this comparison range to 1.77 MPa to 6.50 MPa. Main text. To reach the main text of this paper, click on Final Report. Note that this text is that which appears in Appendix B of the BIPM key comparison database kcdb.bipm.org/. The final report has been peer-reviewed and approved for publication by the APMP, according to the provisions of the CIPM Mutual Recognition Arrangement (CIPM MRA).

Self-Tuning Adaptive-Controller Using Online Frequency Identification

NASA Technical Reports Server (NTRS)

Chiang, W. W.; Cannon, R. H., Jr.

1985-01-01

A real time adaptive controller was designed and tested successfully on a fourth order laboratory dynamic system which features very low structural damping and a noncolocated actuator sensor pair. The controller, implemented in a digital minicomputer, consists of a state estimator, a set of state feedback gains, and a frequency locked loop (FLL) for real time parameter identification. The FLL can detect the closed loop natural frequency of the system being controlled, calculate the mismatch between a plant parameter and its counterpart in the state estimator, and correct the estimator parameter in real time. The adaptation algorithm can correct the controller error and stabilize the system for more than 50% variation in the plant natural frequency, compared with a 10% stability margin in frequency variation for a fixed gain controller having the same performance at the nominal plant condition. After it has locked to the correct plant frequency, the adaptive controller works as well as the fixed gain controller does when there is no parameter mismatch. The very rapid convergence of this adaptive system is demonstrated experimentally, and can also be proven with simple root locus methods.

Optimal Load-Side Control for Frequency Regulation in Smart Grids

DOE Office of Scientific and Technical Information (OSTI.GOV)

Zhao, Changhong; Mallada, Enrique; Low, Steven

Frequency control rebalances supply and demand while maintaining the network state within operational margins. It is implemented using fast ramping reserves that are expensive and wasteful, and which are expected to become increasingly necessary with the current acceleration of renewable penetration. The most promising solution to this problem is the use of demand response, i.e., load participation in frequency control. Yet it is still unclear how to efficiently integrate load participation without introducing instabilities and violating operational constraints. In this paper, we present a comprehensive load-side frequency control mechanism that can maintain the grid within operational constraints. In particular, ourmore » controllers can rebalance supply and demand after disturbances, restore the frequency to its nominal value, and preserve interarea power flows. Furthermore, our controllers are distributed (unlike the currently implemented frequency control), can allocate load updates optimally, and can maintain line flows within thermal limits. We prove that such a distributed load-side control is globally asymptotically stable and robust to unknown load parameters. We illustrate its effectiveness through simulations.« less

Effect of Initial Condition on Subsonic Jet Noise from Two Rectangular Nozzles

NASA Technical Reports Server (NTRS)

Zaman, K. B. M. Q.

2012-01-01

Differences in jet noise data from two small 8:1 aspect ratio nozzles are investigated experimentally. The interiors of the two nozzles are identical but one has a thin-lip at the exit while the has a perpendicular face at the exit (thick-lip). It is found that the thin-lip nozzle is substantially noisier throughout the subsonic Mach number range. As much as 5dB difference in OASPL is noticed around Mj =0.96. Hot-wire measurements are carried out for the characteristics of the exit boundary layer and, overall, the noise difference can be ascribed to differences in the boundary layer state. The boundary layer of the quieter (thick-lip) nozzle goes through transition around M(sub j) =0.25 and at higher M(sub j) it remains "nominally turbulent". In comparison, the boundary layer of the thin-lip nozzle is found to remain "nominally laminar". at high subsonic conditions. The nominally laminar state involves significantly larger turbulence intensities commensurate with the higher radiated noise.

Using Whispering-Gallery-Mode Resonators for Refractometry

NASA Technical Reports Server (NTRS)

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

2010-01-01

A method of determining the refractive and absorptive properties of optically transparent materials involves a combination of theoretical and experimental analysis of electromagnetic responses of whispering-gallery-mode (WGM) resonator disks made of those materials. The method was conceived especially for use in studying transparent photorefractive materials, for which purpose this method affords unprecedented levels of sensitivity and accuracy. The method is expected to be particularly useful for measuring temporally varying refractive and absorptive properties of photorefractive materials at infrared wavelengths. Still more particularly, the method is expected to be useful for measuring drifts in these properties that are so slow that, heretofore, the properties were assumed to be constant. The basic idea of the method is to attempt to infer values of the photorefractive properties of a material by seeking to match (1) theoretical predictions of the spectral responses (or selected features thereof) of a WGM of known dimensions made of the material with (2) the actual spectral responses (or selected features thereof). Spectral features that are useful for this purpose include resonance frequencies, free spectral ranges (differences between resonance frequencies of adjacently numbered modes), and resonance quality factors (Q values). The method has been demonstrated in several experiments, one of which was performed on a WGM resonator made from a disk of LiNbO3 doped with 5 percent of MgO. The free spectral range of the resonator was approximately equal to 3.42 GHz at wavelengths in the vicinity of 780 nm, the smallest full width at half maximum of a mode was approximately equal to 50 MHz, and the thickness of the resonator in the area of mode localization was 30 microns. In the experiment, laser power of 9 mW was coupled into the resonator with an efficiency of 75 percent, and the laser was scanned over a frequency band 9 GHz wide at a nominal wavelength of approximately equal to 780 nm. Resonance frequencies were measured as functions of time during several hours of exposure to the laser light. The results of these measurements, plotted in the figure, show a pronounced collective frequency drift of the resonator modes. The size of the drift has been estimated to correspond to a change of 8.5 x 10(exp -5) in the effective ordinary index of refraction of the resonator material.

Self-sustained magnetoelectric oscillations in magnetic resonant tunneling structures.

PubMed

Ertler, Christian; Fabian, Jaroslav

2008-08-15

The dynamic interplay of transport, electrostatic, and magnetic effects in the resonant tunneling through ferromagnetic quantum wells is theoretically investigated. It is shown that the carrier-mediated magnetic order in the ferromagnetic region not only induces, but also takes part in intrinsic, robust, and sustainable high-frequency current oscillations over a large window of nominally steady bias voltages. This phenomenon could spawn a new class of quantum electronic devices based on ferromagnetic semiconductors.

ADAPTable Sensor Systems Phase 2. Topic 2: Reusable Core Software. Distributed Synchronization Software for the Sensor Nodes

DTIC Science & Technology

2015-03-01

Wireless Sensor Network Using Unreliable GPS Signals Daniel R. Fuhrmann*, Joshua Stomberg§, Saeid Nooshabadi*§ Dustin McIntire†, William Merill... wireless sensor network , when the timing jitter is subject to a empirically determined bimodal non-Gaussian distribution. Specifically, we 1) estimate the...over a nominal 19.2 MHz frequency with an adjustment made every four hours. Index Terms— clock synchronization, GPS, wireless sensor networks , Kalman

Correlation of vapor phase infrared spectra and regioisomeric structure in synthetic cannabinoids

NASA Astrophysics Data System (ADS)

Smith, Lewis W.; Thaxton-Weissenfluh, Amber; Abiedalla, Younis; DeRuiter, Jack; Smith, Forrest; Clark, C. Randall

2018-05-01

The twelve 1-n-pentyl-2-, 3-, 4-, 5-, 6- and 7-(1- and 2-naphthoyl)-indoles each have the same substituents attached to the indole ring, identical elemental composition (C24H23NO) yielding identical nominal and accurate masses. These twelve isomers cover all possible positions of carbonyl bridge substitution for both indole (positons 2-7) and naphthalene rings (positions 1 and 2). Regioisomeric compounds can represent significant challenges for mass based analytical methods however, infrared spectroscopy is a powerful tool for the identification of positional isomers in organic compounds. The vapor phase infrared spectra of these twelve uniquely similar compounds were evaluated in GC-IR experiments. These spectra show the bridge position on the indole ring is a dominating influence over the carbonyl absorption frequency observed for these compounds. Substitution on the pyrrole moiety of the indole ring yields the lowest Cdbnd O frequency values for position 2 and 3 giving a narrow range from 1656 to 1654 cm-1. Carbonyl absorption frequencies are higher when the naphthoyl group is attached to the benzene portion of the indole ring yielding absorption values from 1674 to 1671 cm-1. The aliphatic stretching bands in the 2900 cm-1 region yield a consistent triplet pattern because the N-alkyl substituent tail group remains unchanged for all twelve regioisomers. The asymmetric CH2 stretch is the most intense of these three bands. Changes in positional bonding for both the indole and naphthalene ring systems results in unique patterns within the 700 wavenumber out-of-plane region and these absorption bands are different for all 12 regioisomers.

Application of Wave Distribution Function Method to the ERG/PWE Data

NASA Astrophysics Data System (ADS)

Ota, M.; Kasahara, Y.; Matsuda, S.; Kojima, H.; Matsuoka, A.; Hikishima, M.; Kasaba, Y.; Ozaki, M.; Yagitani, S.; Tsuchiya, F.; Kumamoto, A.

2017-12-01

The ERG (Arase) satellite was launched on 20 December 2016 to study acceleration and loss mechanisms of relativistic electrons in the Earth's magnetosphere. The Plasma Wave Experiment (PWE), which is one of the science instruments on board the ERG satellite, measures electric field and magnetic field. The PWE consists of three sub-systems; EFD (Electric Field Detector), OFA/WFC (Onboard Frequency Analyzer and Waveform Capture), and HFA (High Frequency Analyzer).The OFA/WFC measures electromagnetic field spectra and raw waveforms in the frequency range from few Hz to 20 kHz. The OFA produces three kind of data; OFA-SPEC (power spectrum), OFA-MATRIX (spectral matrix), and OFA-COMPLEX (complex spectrum). The OFA-MATRIX measures ensemble averaged complex cross-spectra of two electric field components, and of three magnetic field components. The OFA-COMPLEX measures instantaneous complex spectra of electric and magnetic fields. These data are produced every 8 seconds in the nominal mode, and it can be used for polarization analysis and wave propagation direction finding.In general, spectral matrix composed by cross-spectra of observed signals is used for direction finding, and many algorithms have been proposed. For example, Means method and SVD method can be applied on the assumption that the spectral matrix is consists of a single plane wave, while wave distribution function (WDF) method is applicable even to the data in which multiple numbers of plane waves are simultaneously included. In this presentation, we introduce the results when the WDF method is applied to the ERG/PWE data.

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

NASA Technical Reports Server (NTRS)

Duerksen, Gary L.; Krainak, Michael A.

1999-01-01

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

High-transition-temperature superconductors in the Nb-Al-Ge system

DOEpatents

Giorgi, A.L.; Szklarz, E.G.

1972-09-26

The patent describes superconducting materials of the nominal composition Nb(x)Al(y)Ge(l-y), where x is in the range of 1.9 to 2.8 and y is in the range of 0.5 to 0.9, having transition temperatures in the 19 -20K. range which are readily produced by annealing arc-melted compositions, or cold-pressed, heat-treated compositions at moderate temperatures for reasonably long times (about 50 hours).

Dry friction avalanches: experiment and theory.

PubMed

Buldyrev, Sergey V; Ferrante, John; Zypman, Fredy R

2006-12-01

Experimental evidence and theoretical models are presented supporting the conjecture that dry friction stick-slip is described by self-organized criticality. We use the data, obtained with a pin-on-disk tribometer set to measure lateral force, to examine the variation of the friction force as a function of time. We study nominally flat surfaces of matching aluminum and steel. The probability distribution of force drops follows a negative power law with exponents mu in the range 3.2-3.5. The frequency power spectrum follows a 1/f alpha pattern with alpha in the range 1-1.8. We first compare these experimental results with the well-known Robin Hood model of self-organized criticality. We find good agreement between theory and experiment for the force-drop distribution but not for the power spectrum. We explain this on a physical basis and propose a model which takes explicitly into account the stiffness and inertia of the tribometer. Specifically, we numerically solve the equation of motion of a block on a friction surface pulled by a spring and show that for certain spring constants the motion is characterized by the same power law spectrum as in experiments. We propose a physical picture relating the fluctuations of the force drops to the microscopic geometry of the surface.

A Diagnostically Promising Technique for Tallying Nominal Reference Errors in the Narratives of School-Aged Children with Foetal Alcohol Spectrum Disorders (FASD)

ERIC Educational Resources Information Center

Thorne, John C.; Coggins, Truman

2008-01-01

Background: Foetal Alcohol Spectrum Disorders (FASD) include the range of disabilities that occur in children exposed to alcohol during pregnancy, with Foetal Alcohol Syndrome (FAS) on the severe end of the spectrum. Clinical research has documented a range of cognitive, social, and communication deficits in FASD and it indicates the need for…

TEFLON BELLOWS PULSE GENERATORS FOR SOLVENT EXTRACTION PULSE COLUMNS

DOE Office of Scientific and Technical Information (OSTI.GOV)

McCarthy, P.B.

1954-01-01

A Teflon bellows-type pulse generator is described which consists of two 3-in. nominal diameter Teflon bellows mounted on either end of a flanged spool piece and rigidly connected internally by a push rod so that the two of bellows move in tandem. The ends of the two bellows are closed by means of blind flanges. Tne spool piece is designed for insertion in a 6-in. diameter nozzle on a solvent extraction pulse column. The double bellows arrangement constitutes a safety feature to prevent loss of the column contents in the event of failure of the inner bellows in contact withmore » column solution. Failure of the inner bellows may be detected by a conductivity probe mounted in the air space inside of the double bellows assembly. Reciprocating motion is imcrank arm rigidly connected through a cross head and push rod to the face of the external bellows flange. The push rod is guided by means of linear ball bushings. Frequency variation over a range of 30 to 100 cycles/ min.was obtained by use of a Thymotrol-controlled electric motor to drive the crank arm. Variable stroke adjustment (0 to 1-in. range) was possible by adjustment of linkages on the crank arm. A load compensating spring was founnd desirable to counteract the thrust on the push rod resulting tom the static pressure at the bottom of the solvent extraction column. Without the spring, accelerated wear of the bearing on the crank arm occured. The pulse generator operated uneventfully for 1776 hours (6.61x lO/sup 6/ cycles) at a frequency of 62 cycles/min. and a bellows travel of l-in. (equivalent to a displacement of 1.6 in. in a 3-in. diam. column). (auth)« less

Heteronuclear Adiabatic Relaxation Dispersion (HARD) for quantitative analysis of conformational dynamics in proteins.

PubMed

Traaseth, Nathaniel J; Chao, Fa-An; Masterson, Larry R; Mangia, Silvia; Garwood, Michael; Michaeli, Shalom; Seelig, Burckhard; Veglia, Gianluigi

2012-06-01

NMR relaxation methods probe biomolecular motions over a wide range of timescales. In particular, the rotating frame spin-lock R(1ρ) and Carr-Purcell-Meiboom-Gill (CPMG) R(2) experiments are commonly used to characterize μs to ms dynamics, which play a critical role in enzyme folding and catalysis. In an effort to complement these approaches, we introduced the Heteronuclear Adiabatic Relaxation Dispersion (HARD) method, where dispersion in rotating frame relaxation rate constants (longitudinal R(1ρ) and transverse R(2ρ)) is created by modulating the shape and duration of adiabatic full passage (AFP) pulses. Previously, we showed the ability of the HARD method to detect chemical exchange dynamics in the fast exchange regime (k(ex)∼10(4)-10(5) s(-1)). In this article, we show the sensitivity of the HARD method to slower exchange processes by measuring R(1ρ) and R(2ρ) relaxation rates for two soluble proteins (ubiquitin and 10C RNA ligase). One advantage of the HARD method is its nominal dependence on the applied radio frequency field, which can be leveraged to modulate the dispersion in the relaxation rate constants. In addition, we also include product operator simulations to define the dynamic range of adiabatic R(1ρ) and R(2ρ) that is valid under all exchange regimes. We conclude from both experimental observations and simulations that this method is complementary to CPMG-based and rotating frame spin-lock R(1ρ) experiments to probe conformational exchange dynamics for biomolecules. Finally, this approach is germane to several NMR-active nuclei, where relaxation rates are frequency-offset independent. Copyright © 2012 Elsevier Inc. All rights reserved.

Subcutaneous interferon β-1a in the treatment of clinically isolated syndromes: 3-year and 5-year results of the phase III dosing frequency-blind multicentre REFLEXION study.

PubMed

Comi, Giancarlo; De Stefano, Nicola; Freedman, Mark S; Barkhof, Frederik; Uitdehaag, Bernard M J; de Vos, Marlieke; Marhardt, Kurt; Chen, Liang; Issard, Delphine; Kappos, Ludwig

2017-04-01

Early treatment following a first clinical demyelinating event (FCDE) delays further disease activity in patients with multiple sclerosis (MS). This study determined the effects of early versus delayed treatment (DT) with subcutaneous interferon (sc IFN) β-1a 44 μg in patients with an FCDE up to 60 months postrandomisation. Patients who completed the 24-month double-blind REFLEX (REbif FLEXible dosing in early MS) study entered an extension (REFLEXION, REbif FLEXible dosing in early MS extensION): patients initially randomised to sc IFN β-1a and not reaching clinically definite MS (clinically definite MS, CDMS (second attack or sustained Expanded Disability Status Scale (EDSS) score increase)) continued original treatment (three times weekly (tiw) or once weekly (qw)); placebo patients switched to tiw (DT); patients with CDMS switched to tiw. Clinical, MRI and adverse event data up to month 60 are reported. 402/517 (77.8%) REFLEX patients entered REFLEXION (DT, n=133; tiw, n=127; qw, n=142). At month 60, cumulative probability of CDMS was: DT 44.6%; qw 40.7% (nominal p=0.084 vs DT); tiw 39.2% (nominal p=0.032 vs DT). Cumulative probability of McDonald MS conversion (CDMS or new MRI activity) at month 60 was also reduced for tiw versus DT (nominal p<0.001). At month 60, mean cumulative numbers of new T2, gadolinium-enhancing and T1 hypointense lesions were lower with sc IFN β-1a qw (nominal p<0.05) and tiw versus DT (nominal p<0.001); T2 and T1 hypointense lesion volume change was lower for sc IFN β-1a tiw versus DT (nominal p<0.01). Treatment was well tolerated; fewer patients receiving tiw versus qw were positive for neutralising or binding antibodies. Over 5 years in patients presenting with an FCDE, early sc IFN β-1a tiw administration versus DT prolonged time to CDMS and McDonald MS, and reduced overall MRI activity. NCT00813709; Results. Published by the BMJ Publishing Group Limited. For permission to use (where not already granted under a licence) please go to http://www.bmj.com/company/products-services/rights-and-licensing/.

Flow and Acoustic Features of a Mach 0.9 Free Jet Using High-Frequency Excitation

NASA Astrophysics Data System (ADS)

Upadhyay, Puja; Alvi, Farrukh

2016-11-01

This study focuses on active control of a Mach 0.9 (ReD = 6 ×105) free jet using high-frequency excitation for noise reduction. Eight resonance-enhanced microjet actuators with nominal frequencies of 25 kHz (StD 2 . 2) are used to excite the shear layer at frequencies that are approximately an order of magnitude higher than the jet preferred frequency. The influence of control on mean and turbulent characteristics of the jet is studied using Particle Image Velocimetry. Additionally, far-field acoustic measurements are acquired to estimate the effect of pulsed injection on noise characteristics of the jet. Flow field measurements revealed that strong streamwise vortex pairs, formed as a result of control, result in a significantly thicker initial shear layer. This excited shear layer is also prominently undulated, resulting in a modified initial velocity profile. Also, the distribution of turbulent kinetic energy revealed that forcing results in increased turbulence levels for near-injection regions, followed by a global reduction for all downstream locations. Far-field acoustic measurements showed noise reductions at low to moderate frequencies. Additionally, an increase in high-frequency noise, mostly dominated by the actuators' resonant noise, was observed. AFOSR and ARO.

A cost/benefit analysis of commercial fusion-fission hybrid reactor development

NASA Astrophysics Data System (ADS)

Kostoff, Ronald N.

1983-04-01

A simple algorithm was developed that allows rapid computation of the ratio, R, of present worth of benefits to present worth of hybrid R&D program costs as a function of potential hybrid unit electricity cost savings, discount rate, electricity demand growth rate, total hybrid R&D program cost, and time to complete a demonstration reactor. In the sensitivity study, these variables were assigned nominal values (unit electricity cost savings of 4 mills/kW-hr, discount rate of 4%/year, growth rate of 2.25%/year, total R&D program cost of 20 billion, and time to complete a demonstration reactor of 30 years), and the variable of interest was varied about its nominal value. Results show that R increases with decreasing discount rate and increasing unit electricity savings and ranges from 4 to 94 as discount rate ranges from 5 to 3%/year and unit electricity savings range from 2 to 6 mills/kW-hr. R increases with increasing growth rate and ranges from 3 to 187 as growth rate ranges from 1 to 3.5%/year and unit electricity cost savings range from 2 to 6 mills/kW-hr. R attains a maximum value when plotted against time to complete a demonstration reactor. The location of this maximum value occurs at shorter completion times as discount rate increases, and this optimal completion time ranges from 20 years for a discount rate of 4%/year to 45 years for a discount rate of 3%/year.

Resolving the grain boundary and lattice impedance of hot-pressed Li 7La 3Zr 2O 12 garnet electrolytes

DOE PAGES

Tenhaeff, Wyatt E.; Wang, Yangyang; Sokolov, Alexei P.; ...

2013-07-24

Here, the cubic-stabilized garnet solid electrolyte with a nominal composition of Li 6.28Al 0.24La 3Zr 2O 12 is thoroughly characterized by impedance spectroscopy. By varying the frequency of the applied AC signal over 11 orders of magnitude for characterizations from –100 to +60 °C, the relative contributions of grain and grain boundary conduction are unambiguously resolved.

Adaptive Beamforming Algorithms for High Resolution Microwave Imaging

DTIC Science & Technology

1991-04-01

frequency- and phase -locked. With a system of radio camera size it must be assumed that oscillators will drift and, similarly, that electronic circuits in...propagation-induced phase errors an array as large as the one under discussion is likely to experience differ- ent weather conditions across it. The nominal...human optical system. Such a passing-scene display with human optical resolving power would be available to the air - man at night as well as during the

Cytogenetic studies in human blood lymphocytes exposed in vitro to radiofrequency radiation at a cellular telephone frequency (835.62 MHz, FDMA).

PubMed

Vijayalaxmi; Leal, B Z; Meltz, M L; Pickard, W F; Bisht, K S; Roti Roti JL; Straube, W L; Moros, E G

2001-01-01

Freshly collected peripheral blood samples from four healthy human volunteers were diluted with RPMI 1640 tissue culture medium and exposed in sterile T-75 tissue culture flasks in vitro for 24 h to 835.62 MHz radiofrequency (RF) radiation, a frequency employed for customer-to-base station transmission of cellular telephone communications. An analog signal was used, and the access technology was frequency division multiple access (FDMA, continuous wave). A nominal net forward power of 68 W was used, and the nominal power density at the center of the exposure flask was 860 W/m(2). The mean specific absorption rate in the exposure flask was 4.4 or 5.0 W/kg. Aliquots of diluted blood that were sham-exposed or exposed in vitro to an acute dose of 1.50 Gy of gamma radiation were used as negative or positive controls. Immediately after the exposures, the lymphocytes were stimulated with a mitogen, phytohemagglutinin, and cultured for 48 or 72 h to determine the extent of genetic damage, as assessed from the frequencies of chromosomal aberrations and micronuclei. The extent of alteration in the kinetics of cell proliferation was determined from the mitotic indices in 48-h cultures and from the incidence of binucleate cells in 72-h cultures. The data indicated no significant differences between RF-radiation- and sham-exposed lymphocytes with respect to mitotic indices, incidence of exchange aberrations, excess fragments, binucleate cells, and micronuclei. In contrast, the response of the lymphocytes exposed to gamma radiation was significantly different from both RF-radiation- and sham-exposed cells for all of these indices. Thus, under the experimental conditions tested, there is no evidence for the induction of chromosomal aberrations and micronuclei in human blood lymphocytes exposed in vitro for 24 h to 835.62 MHz RF radiation at SARs of 4.4 or 5.0 W/kg.

Photorefraction in the ultraviolet: Materials and effects

NASA Astrophysics Data System (ADS)

Laeri, F.; Jungen, R.; Angelow, G.; Vietze, U.; Engel, T.; Würtz, M.; Hilgenberg, D.

1995-10-01

Doped as well as nominally pure crystals of Lithium Niobate (LiNbO3), ι-Arginine Phosphate (LAP), Lithium Iodate (LiIO3), Potassium Dihydrogen Phosphate (KDP), Lithium Formate (LFM), Beta-Barium Borate (BBO), and lithium tetra borate were grown and investigated for photorefractive effects at ultraviolet wavelengths down to 333 nm. In nominally undoped LiNbO3 crystals strong beam coupling effects were observed. In contrast to the visible we revealed a diffusion-dominated charge transport mechanism based on holes, and a low photovoltaic field in the order of 550 V/cm. With such a crystal we investigated the modulation transfer function of a lensless image projection system based on a phase conjugation scheme. A spatial frequency response beyond 2800 line pairs per millimeter was observed. Photorefractive beam coupling was also obtained in LiIO3. Light-induced scattering was detected in iron-doped LiIO3 whereas as-grown LAP material did not exhibit any observable photorefractive effects. However, 100 kV X-ray irradiation seems to induce material defects which can lead to weak light-induced scattering at 351 nm. In all other above-mentioned materials, doped as well as undoped, light-induced scattering could not be observed. On the other hand, this is appreciated in all the applications where the crystals are used as nonlinear material for optical frequency conversion.

Impact verification of space suit design for space station

NASA Technical Reports Server (NTRS)

Fish, Richard H.

1987-01-01

The ballistic limits of single sheet and double sheet structures made of 6061 T6 Aluminum of 1.8 mm and larger nominal thickness were investigated for projectiles of 1.5 mm diameter fired in the Vertical Gun Range Test Facility and NASA Ames Research Center. The hole diameters and sheet deformation behavior were studied for various ratios of sheet spacing to projectile diameter. The results indicate that for projectiles of less than 1.5 mm diameter the ballistic limit exceeds the nominal 10 km/sec orbital debris encounter velocity, if a single-sheet suit of 1.8 mm thickness is behind a single bumper sheet of 1 mm thickness spaced 12.5 mm apart.

Nominal SARAL Transfer Function

NASA Technical Reports Server (NTRS)

Arnold, David A.; Lemoine, Frank (Editor)

2015-01-01

This paper gives a calculation of the range correction and cross section of the SARAL (Satellite with Argos and ALtiKa) Indian/French ocean radar satellite retroreflector array assuming the cube corners are coated and have a dihedral angle offset of about 1.5 arcseconds to account for velocity aberration. The cubes are assumed to all have the same orientation within the mounting. The derived range correction may be applied in precise orbit determination analyses that use Satellite Laser Ranging (SLR) data to SARAL.

High frequency two-stage pulse tube cryocooler with base temperature below 20 K

NASA Astrophysics Data System (ADS)

Yang, L. W.; Thummes, G.

2005-02-01

High frequency (30-50 Hz) multi-stage pulse tube coolers that are capable of reaching temperatures close to 20 K or even lower are a subject of recent research and development activities. This paper reports on the design and test of a two-stage pulse tube cooler which is driven by a linear compressor with nominal input power of 200 W at an operating frequency of 30-45 Hz. A parallel configuration of the two pulse tubes is used with the warm ends of the pulse tubes located at ambient temperature. For both stages, the regenerator matrix consists of a stack of stainless steel screen. At an operating frequency of 35 Hz and with the first stage at 73 K a lowest stationary temperature of 19.6 K has been achieved at the second stage. The effects of input power, frequency, average pressure, and cold head orientation on the cooling performance are also reported. An even lower no-load temperature can be expected from the use of lead or other regenerator materials of high heat capacity in the second stage.

Implementing a Digital Phasemeter in an FPGA

NASA Technical Reports Server (NTRS)

Rao, Shanti R.

2008-01-01

Firmware for implementing a digital phasemeter within a field-programmable gate array (FPGA) has been devised. In the original application of this firmware, the phase that one seeks to measure is the difference between the phases of two nominally-equal-frequency heterodyne signals generated by two interferometers. In that application, zero-crossing detectors convert the heterodyne signals to trains of rectangular pulses, the two pulse trains are fed to a fringe counter (the major part of the phasemeter) controlled by a clock signal having a frequency greater than the heterodyne frequency, and the fringe counter computes a time-averaged estimate of the difference between the phases of the two pulse trains. The firmware also does the following: Causes the FPGA to compute the frequencies of the input signals; Causes the FPGA to implement an Ethernet (or equivalent) transmitter for readout of phase and frequency values; and Provides data for use in diagnosis of communication failures. The readout rate can be set, by programming, to a value between 250 Hz and 1 kHz. Network addresses can be programmed by the user.

Search for Lorentz Violation in a Short-Range Gravity Experiment

NASA Astrophysics Data System (ADS)

Bennett, D.; Skavysh, V.; Long, J.

2011-12-01

An experimental test of the Newtonian inverse square law at short range has been used to set limits on Lorentz violation in the pure gravity sector of the Standard-Model Extension. On account of the planar test mass geometry, nominally null with respect to 1/r2 forces, the limits derived for the SME coefficients of Lorentz violation are on the order bar sJK ˜ 104 .

A Singular Perturbation Approach for Time-Domain Assessment of Phase Margin

NASA Technical Reports Server (NTRS)

Zhu, J. Jim; Yang, Xiaojing; Hodel, A Scottedward

2010-01-01

This paper considers the problem of time-domain assessment of the Phase Margin (PM) of a Single Input Single Output (SISO) Linear Time-Invariant (LTI) system using a singular perturbation approach, where a SISO LTI fast loop system, whose phase lag increases monotonically with frequency, is introduced into the loop as a singular perturbation with a singular perturbation (time-scale separation) parameter Epsilon. First, a bijective relationship between the Singular Perturbation Margin (SPM) max and the PM of the nominal (slow) system is established with an approximation error on the order of Epsilon(exp 2). In proving this result, relationships between the singular perturbation parameter Epsilon, PM of the perturbed system, PM and SPM of the nominal system, and the (monotonically increasing) phase of the fast system are also revealed. These results make it possible to assess the PM of the nominal system in the time-domain for SISO LTI systems using the SPM with a standardized testing system called "PM-gauge," as demonstrated by examples. PM is a widely used stability margin for LTI control system design and certification. Unfortunately, it is not applicable to Linear Time-Varying (LTV) and Nonlinear Time-Varying (NLTV) systems. The approach developed here can be used to establish a theoretical as well as practical metric of stability margin for LTV and NLTV systems using a standardized SPM that is backward compatible with PM.

78 FR 37877 - Request for Transit Rail Advisory Committee for Safety (TRACS) Nominations

Federal Register 2010, 2011, 2012, 2013, 2014

2013-06-24

... transportation as FTA implements new statutory authority for public transportation safety oversight. FOR FURTHER... public transportation. Therefore, TRACS membership will be reconfigured to reflect a broader range of... DEPARTMENT OF TRANSPORTATION Federal Transit Administration Request for Transit Rail Advisory...

Statistical plant set estimation using Schroeder-phased multisinusoidal input design

NASA Technical Reports Server (NTRS)

Bayard, D. S.

1992-01-01

A frequency domain method is developed for plant set estimation. The estimation of a plant 'set' rather than a point estimate is required to support many methods of modern robust control design. The approach here is based on using a Schroeder-phased multisinusoid input design which has the special property of placing input energy only at the discrete frequency points used in the computation. A detailed analysis of the statistical properties of the frequency domain estimator is given, leading to exact expressions for the probability distribution of the estimation error, and many important properties. It is shown that, for any nominal parametric plant estimate, one can use these results to construct an overbound on the additive uncertainty to any prescribed statistical confidence. The 'soft' bound thus obtained can be used to replace 'hard' bounds presently used in many robust control analysis and synthesis methods.

Lift capability prediction for helicopter rotor blade-numerical evaluation

NASA Astrophysics Data System (ADS)

Rotaru, Constantin; Cîrciu, Ionicǎ; Luculescu, Doru

2016-06-01

The main objective of this paper is to describe the key physical features for modelling the unsteady aerodynamic effects found on helicopter rotor blade operating under nominally attached flow conditions away from stall. The unsteady effects were considered as phase differences between the forcing function and the aerodynamic response, being functions of the reduced frequency, the Mach number and the mode forcing. For a helicopter rotor, the reduced frequency at any blade element can't be exactly calculated but a first order approximation for the reduced frequency gives useful information about the degree of unsteadiness. The sources of unsteady effects were decomposed into perturbations to the local angle of attack and velocity field. The numerical calculus and graphics were made in FLUENT and MAPLE soft environments. This mathematical model is applicable for aerodynamic design of wind turbine rotor blades, hybrid energy systems optimization and aeroelastic analysis.

Low-frequency dynamics of pressure-induced turbulent separation bubbles

NASA Astrophysics Data System (ADS)

Weiss, Julien; Mohammed-Taifour, Abdelouahab; Lefloch, Arnaud

2017-11-01

We experimentally investigate a pressure-induced turbulent separation bubble (TSB), which is generated on a flat test surface through a combination of adverse and favorable pressure gradients imposed on a nominally two-dimensional, incompressible, turbulent boundary layer. We probe the flow using piezo-resistive pressure transducers, MEMS shear-stress sensors, and high-speed, 2D-2C, PIV measurements. Through the use of Fourier analysis of the wall-pressure fluctuations and Proper Orthogonal Decomposition of the velocity fields, we show that this type of flow is characterized by a self-induced, low-frequency contraction and expansion - called breathing - of the TSB. The dominant Strouhal number of this motion, based on the TSB length and the incoming velocity in the potential flow, is of the order of 0.01. We compare this motion to the low-frequency dynamics observed in laminar separation bubbles (LSBs), geometry-induced TSBs, and shock-induced separated flows.

An Analysis of the High Frequency Vibrations in Early Thematic Mapper Scenes

NASA Technical Reports Server (NTRS)

Kogut, J.; Larduinat, E.

1985-01-01

The motion of the mirrors in the thematic mapper (TM) and multispectral scanner (MSS) instruments, and the motion of other devices, such as the TDRSS antenna drive, and solar array drives onboard LANDSAT-4 cause vibrations to propagate through the spacecraft. These vibrations as well as nonlinearities in the scanning motion of the TM mirror can cause the TM detectors to point away from their nominal positions. Two computer programs, JITTER and SCDFT, were developed as part of the LANDSAT-D Assessment System (LAS), Products and Procedures Analysis (PAPA) program to evaluate the potential effect of high frequency vibrations on the final TM image. The maximum overlap and underlap which were observed for early TM scenes are well within specifications for the ground processing system. The cross scan and scan high frequency vibrations are also within the specifications cited for the flight system.

Frequency-varying synchronous micro-vibration suppression for a MSFW with application of small-gain theorem

NASA Astrophysics Data System (ADS)

Peng, Cong; Fan, Yahong; Huang, Ziyuan; Han, Bangcheng; Fang, Jiancheng

2017-01-01

This paper presents a novel synchronous micro-vibration suppression method on the basis of the small gain theorem to reduce the frequency-varying synchronous micro-vibration forces for a magnetically suspended flywheel (MSFW). The proposed synchronous micro-vibration suppression method not only eliminates the synchronous current fluctuations to force the rotor spinning around the inertia axis, but also considers the compensation caused by the displacement stiffness in the permanent-magnet (PM)-biased magnetic bearings. Moreover, the stability of the proposed control system is exactly analyzed by using small gain theorem. The effectiveness of the proposed micro-vibration suppression method is demonstrated via the direct measurement of the disturbance forces for a MSFW. The main merit of the proposed method is that it provides a simple and practical method in suppressing the frequency varying micro-vibration forces and preserving the nominal performance of the baseline control system.

Direct Adaptive Rejection of Vortex-Induced Disturbances for a Powered SPAR Platform

NASA Technical Reports Server (NTRS)

VanZwieten, Tannen S.; Balas, Mark J.; VanZwieten, James H.; Driscoll, Frederick R.

2009-01-01

The Rapidly Deployable Stable Platform (RDSP) is a novel vessel designed to be a reconfigurable, stable at-sea platform. It consists of a detachable catamaran and spar, performing missions with the spar extending vertically below the catamaran and hoisting it completely out of the water. Multiple thrusters located along the spar allow it to be actively controlled in this configuration. A controller is presented in this work that uses an adaptive feedback algorithm in conjunction with Direct Adaptive Disturbance Rejection (DADR) to mitigate persistent, vortex-induced disturbances. Given the frequency of a disturbance, the nominal DADR scheme adaptively compensates for its unknown amplitude and phase. This algorithm is extended to adapt to a disturbance frequency that is only coarsely known by including a Phase Locked Loop (PLL). The PLL improves the frequency estimate on-line, allowing the modified controller to reduce vortex-induced motions by more than 95% using achievable thrust inputs.

Economic impact of fuel properties on turbine powered business aircraft

NASA Technical Reports Server (NTRS)

Powell, F. D.

1984-01-01

The principal objective was to estimate the economic impact on the turbine-powered business aviation fleet of potential changes in the composition and properties of aviation fuel. Secondary objectives include estimation of the sensitivity of costs to specific fuel properties, and an assessment of the directions in which further research should be directed. The study was based on the published characteristics of typical and specific modern aircraft in three classes; heavy jet, light jet, and turboprop. Missions of these aircraft were simulated by computer methods for each aircraft for several range and payload combinations, and assumed atmospheric temperatures ranging from nominal to extremely cold. Five fuels were selected for comparison with the reference fuel, nominal Jet A. An overview of the data, the mathematic models, the data reduction and analysis procedure, and the results of the study are given. The direct operating costs of the study fuels are compared with that of the reference fuel in the 1990 time-frame, and the anticipated fleet costs and fuel break-even costs are estimated.

Detection of tightly closed flaws by nondestructive testing (NDT) methods in steel and titanium

NASA Technical Reports Server (NTRS)

Rummel, W. D.; Rathke, R. A.; Todd, P. H., Jr.; Tedrow, T. L.; Mullen, S. J.

1976-01-01

X-radiographic, liquid penetrant, ultrasonic, eddy current and magnetic particle testing techniques were optimized and applied to the evaluation of 4340 steel (180 KSI-UTS) and 6Al-4V titanium (STA) alloy specimens. Sixty steel specimens containing a total of 176 fatigue cracks and 60 titanium specimens containing a total of 135 fatigue cracks were evaluated. The cracks ranged in length from .043 cm (0.017 inch) to 1.02 cm (.400 inch) and in depth from .005 cm (.002 inch) to .239 cm (.094 inch) for steel specimens. Lengths ranged from .048 cm (0.019 inch) to 1.03 cm (.407 inch) and depths from 0.010 cm (.004 inch) to .261 cm (0.103 inch) for titanium specimens. Specimen thicknesses were nominally .152 cm (0.060 inch) and 0.635 cm (0.250 inch) and surface finishes were nominally 125 rms. Specimens were evaluated in the "as machined" surface condition, after etch surface and after proof loading in a randomized inspection sequence.

Important influence of respiration on human R-R interval power spectra is largely ignored

NASA Technical Reports Server (NTRS)

Brown, T. E.; Beightol, L. A.; Koh, J.; Eckberg, D. L.

1993-01-01

Frequency-domain analyses of R-R intervals are used widely to estimate levels of autonomic neural traffic to the human heart. Because respiration modulates autonomic activity, we determined for nine healthy subjects the influence of breathing frequency and tidal volume on R-R interval power spectra (fast-Fourier transform method). We also surveyed published literature to determine current practices in this burgeoning field of scientific inquiry. Supine subjects breathed at rates of 6, 7.5, 10, 15, 17.1, 20, and 24 breaths/min and with nominal tidal volumes of 1,000 and 1,500 ml. R-R interval power at respiratory and low (0.06-0.14 Hz) frequencies declined significantly as breathing frequency increased. R-R interval power at respiratory frequencies was significantly greater at a tidal volume of 1,500 than 1,000 ml. Neither breathing frequency nor tidal volume influenced average R-R intervals significantly. Our review of studies reporting human R-R interval power spectra showed that 51% of the studies controlled respiratory rate, 11% controlled tidal volume, and 11% controlled both respiratory rate and tidal volume. The major implications of our analyses are that breathing parameters strongly influence low-frequency as well as respiratory frequency R-R interval power spectra and that this influence is largely ignored in published research.

Static tests of excess ground attenuation at Wallops Flight Center

NASA Astrophysics Data System (ADS)

Sutherland, L. C.; Brown, R.

1981-06-01

An extensive experimental measurement program which evaluated the attenuation of sound for close to horizontal propagation over the ground was designed to replicate, under static conditions, results of the flight measurements carried out earlier by NASA at the same site (Wallops Flight Center). The program consisted of a total of 41 measurement runs of attenuation, in excess of spreading and air absorption losses, for one third octave bands over a frequency range of 50 to 4000 Hz. Each run consisted of measurements at 10 locations up to 675 m, from a source located at nominal elevations of 2.5, or 10 m over either a grassy surface or an adjacent asphalt concrete runway surface. The tests provided a total of over 8100 measurements of attenuation under conditions of low wind speed averaging about 1 m/s and, for most of the tests, a slightly positive temperature gradient, averaging about 0.3 C/m from 1.2 to 7 m. The results of the measurements are expected to provide useful experimental background for the further development of prediction models of near grazing incidence sound propagation losses.

Static tests of excess ground attenuation at Wallops Flight Center

NASA Technical Reports Server (NTRS)

Sutherland, L. C.; Brown, R.

1981-01-01

An extensive experimental measurement program which evaluated the attenuation of sound for close to horizontal propagation over the ground was designed to replicate, under static conditions, results of the flight measurements carried out earlier by NASA at the same site (Wallops Flight Center). The program consisted of a total of 41 measurement runs of attenuation, in excess of spreading and air absorption losses, for one third octave bands over a frequency range of 50 to 4000 Hz. Each run consisted of measurements at 10 locations up to 675 m, from a source located at nominal elevations of 2.5, or 10 m over either a grassy surface or an adjacent asphalt concrete runway surface. The tests provided a total of over 8100 measurements of attenuation under conditions of low wind speed averaging about 1 m/s and, for most of the tests, a slightly positive temperature gradient, averaging about 0.3 C/m from 1.2 to 7 m. The results of the measurements are expected to provide useful experimental background for the further development of prediction models of near grazing incidence sound propagation losses.

Self-diffusion in MgO--a density functional study.

PubMed

Runevall, Odd; Sandberg, Nils

2011-08-31

Density functional theory calculations have been performed to study self-diffusion in magnesium oxide, a model material for a wide range of ionic compounds. Formation energies and entropies of Schottky defects and divacancies were obtained by means of total energy and phonon calculations in supercell configurations. Transition state theory was used to estimate defect migration rates, with migration energies taken from static calculations, and the corresponding frequency factors estimated from the phonon spectrum. In all static calculations we corrected for image effects using either a multipole expansion or an extrapolation to the low concentration limit. It is shown that both methods give similar results. The results for self-diffusion of Mg and O confirm the previously established picture, namely that in materials of nominal purity, Mg diffuses extrinsically by a single vacancy mechanism, while O diffuses intrinsically by a divacancy mechanism. Quantitatively, the current results are in very good agreement with experiments concerning O diffusion, while for Mg the absolute diffusion rate is generally underestimated by a factor of 5-10. The reason for this discrepancy is discussed.

Detection of the lunar body tide by the Lunar Orbiter Laser Altimeter.

PubMed

Mazarico, Erwan; Barker, Michael K; Neumann, Gregory A; Zuber, Maria T; Smith, David E

2014-04-16

The Lunar Orbiter Laser Altimeter instrument onboard the Lunar Reconnaissance Orbiter spacecraft collected more than 5 billion measurements in the nominal 50 km orbit over ∼10,000 orbits. The data precision, geodetic accuracy, and spatial distribution enable two-dimensional crossovers to be used to infer relative radial position corrections between tracks to better than ∼1 m. We use nearly 500,000 altimetric crossovers to separate remaining high-frequency spacecraft trajectory errors from the periodic radial surface tidal deformation. The unusual sampling of the lunar body tide from polar lunar orbit limits the size of the typical differential signal expected at ground track intersections to ∼10 cm. Nevertheless, we reliably detect the topographic tidal signal and estimate the associated Love number h 2 to be 0.0371 ± 0.0033, which is consistent with but lower than recent results from lunar laser ranging. Altimetric data are used to create radial constraints on the tidal deformationThe body tide amplitude is estimated from the crossover dataThe estimated Love number is consistent with previous estimates but more precise.

Stochastic response analysis, order reduction, and output feedback controllers for flexible spacecraft

NASA Technical Reports Server (NTRS)

Hablani, H. B.

1985-01-01

Real disturbances and real sensors have finite bandwidths. The first objective of this paper is to incorporate this finiteness in the 'open-loop modal cost analysis' as applied to a flexible spacecraft. Analysis based on residue calculus shows that among other factors, significance of a mode depends on the power spectral density of disturbances and the response spectral density of sensors at the modal frequency. The second objective of this article is to compare performances of an optimal and a suboptimal output feedback controller, the latter based on 'minimum error excitation' of Kosut. Both the performances are found to be nearly the same, leading us to favor the latter technique because it entails only linear computations. Our final objective is to detect an instability due to truncated modes by representing them as a multiplicative and an additive perturbation in a nominal transfer function. In an example problem it is found that this procedure leads to a narrow range of permissible controller gains, and that it labels a wrong mode as a cause of instability. A free beam is used to illustrate the analysis in this work.

ATS-6 - Radio Beacon Experiment: The first years. [ionospheric and satellite-to-ground electron content

NASA Technical Reports Server (NTRS)

Davies, K.; Fritz, R. B.; Grubb, R. N.; Jones, J. E.

1975-01-01

The Radio Beacon Experiment aboard Applications Technology Satellite-6 (ATS-6) is designed to measure the total electron content and the ionospheric electron content between the satellite and ground. The spaceborne beacon transmits signals on frequencies of 40, 140, and 360 MHz with amplitude modulations of 1 MHz and/or 0.1 MHz for the measurement of modulation phase, Faraday rotation, and amplitude. The modulation phase delays are calibrated in the satellite and in the ground equipment, and the polarization of the emitted signals are predetermined by standard antenna range techniques. The design of the ATS-6 receiver in Boulder, Colorado, is discussed. The antennae are of the short backfire type described by Ehrenspeck (1967), with nominal gains of 13, 19, and 22 dB at 40, 140, and 360 MHz, respectively. Data recording and overall supervision of the receiver is carried out by a 16-bit minicomputer with 8 k of memory. Overall performance of the system is satisfactory. Sample data on the monthly median hourly values of the total electron content, plasmospheric content, and shape factor show distinct seasonal and diurnal variations.

Quantification of the effect of cross-shear and applied nominal contact pressure on the wear of moderately cross-linked polyethylene.

PubMed

Abdelgaied, Abdellatif; Brockett, Claire L; Liu, Feng; Jennings, Louise M; Fisher, John; Jin, Zhongmin

2013-01-01

Polyethylene wear is a great concern in total joint replacement. It is now considered a major limiting factor to the long life of such prostheses. Cross-linking has been introduced to reduce the wear of ultra-high-molecular-weight polyethylene (UHMWPE). Computational models have been used extensively for wear prediction and optimization of artificial knee designs. However, in order to be independent and have general applicability and predictability, computational wear models should be based on inputs from independent experimentally determined wear parameters (wear factors or wear coefficients). The objective of this study was to investigate moderately cross-linked UHMWPE, using a multidirectional pin-on-plate wear test machine, under a wide range of applied nominal contact pressure (from 1 to 11 MPa) and under five different kinematic inputs, varying from a purely linear track to a maximum rotation of +/- 55 degrees. A computational model, based on a direct simulation of the multidirectional pin-on-plate wear tester, was developed to quantify the degree of cross-shear (CS) of the polyethylene pins articulating against the metallic plates. The moderately cross-linked UHMWPE showed wear factors less than half of that reported in the literature for, the conventional UHMWPE, under the same loading and kinematic inputs. In addition, under high applied nominal contact stress, the moderately crosslinked UHMWPE wear showed lower dependence on the degree of CS compared to that under low applied nominal contact stress. The calculated wear coefficients were found to be independent of the applied nominal contact stress, in contrast to the wear factors that were shown to be highly pressure dependent. This study provided independent wear data for inputs into computational models for moderately cross-linked polyethylene and supported the application of wear coefficient-based computational wear models.

Ultrahigh frequency tunability of aperture-coupled microstrip antenna via electric-field tunable BST

NASA Astrophysics Data System (ADS)

Du, Hong-Lei; Xue, Qian; Gao, Xiao-Yang; Yao, Feng-Rui; Lu, Shi-Yang; Wang, Ye-Long; Liu, Chun-Heng; Zhang, Yong-Cheng; Lü, Yue-Guang; Li, Shan-Dong

2015-12-01

A composite ceramic with nominal composition of 45.0 wt%(Ba0.5Sr0.5)TiO3-55.0 wt%MgO (acronym is BST-MgO) is sintered for fabricating a frequency reconfigurable aperture-coupled microstrip antenna. The calcined BST-MgO composite ceramic exhibits good microwave dielectric properties at X-band with appropriate dielectric constant ɛr around 85, lower dielectric loss tan δ about 0.01, and higher permittivity tunability 14.8% at 8.33 kV/cm. An ultrahigh E-field tunability of working frequency up to 11.0% (i.e., from 9.1 GHz to 10.1 GHz with a large frequency shift of 1000 MHz) at a DC bias field from 0 to 8.33 kV/cm and a considerably large center gain over 7.5 dB are obtained in the designed frequency reconfigurable microstrip antenna. These results demonstrate that BST materials are promising for the frequency reconfigurable antenna. Project supported by the National Natural Science Foundation of China (Grant No. 11074040) and the Key Project of Shandong Provincial Department of Science and Technology, China (Grant No. ZR2012FZ006).

Impact of atmospheric uncertainties and viscous interaction effects on the performance of aeroassisted orbital transfer vehicles

NASA Technical Reports Server (NTRS)

Talay, T. A.; White, N. H.; Naftel, J. C.

1984-01-01

Simulations of aerobraking trajectories of aeroassisted orbital transfer vehicles (AOTV's) returning from geosynchronous orbit were analyzed to examine the effects of high-altitude viscous interactions and off-nominal atmospheres on AOTV return weight, heating, and loads performance. Viscous interaction effects encountered at high altitudes had little detrimental effect on the return weight capabilities for AOTV's representing a range of lift/drag ratios. Most of the AOTV return weight increase over an all-propulsive OTV occurred for a low lift/drag ratio. Smaller increases in return weight were observed for higher lift/drag ratios, at the expense of significantly higher heating and aerodynamic loads. Off-nominal atmospheres based on Shuttle-derived data and multipliers on a U.S. Standard Atmosphere were considered. AOTV's intended for entry under standard atmospheric conditions either deorbited during the pass through the off-nominal atmospheres or missed the target phasing orbit by wide margins. The AOTV's could successfully negotiate these atmospheres when new bank-angle histories were implemented with little loss and sometimes with a gain in return weight.

76 FR 11195 - Request for Nominations of Members To Serve on the Census Scientific Advisory Committee

Federal Register 2010, 2011, 2012, 2013, 2014

2011-03-01

..., econometrics, cognitive psychology, and computer science as they pertain to the full range of Census Bureau... technical expertise from the following disciplines: demography, economics, geography, psychology, statistics..., psychology, statistics, survey methodology, social and behavioral sciences, Information Technology, computing...

Stabilizing Microwave Frequency of a Photonic Oscillator

NASA Technical Reports Server (NTRS)

Maleki, Lute; Yu, Nan; Tu, Meirong

2006-01-01

A scheme for stabilizing the frequency of a microwave signal is proposed that exploits the operational characteristics of a coupled optoelectronic oscillator (COEO) and related optoelectronic equipment. An essential element in the scheme is a fiber mode-locked laser (MLL), the optical frequency of which is locked to an atomic transition. In this scheme, the optical frequency stability of the mode-locked laser is transferred to that of the microwave in the same device. Relative to prior schemes for using wideband optical frequency comb to stabilize microwave signals, this scheme is simpler and lends itself more readily to implementation in relatively compact, rugged equipment. The anticipated development of small, low-power, lightweight, highly stable microwave oscillators based on this scheme would afford great benefits in communication, navigation, metrology, and fundamental sciences. COEOs of various designs, at various stages of development, in some cases called by different names, have been described in a number of prior NASA Tech Briefs articles. A COEO is an optoelectronic apparatus that generates both short (picosecond) optical pulses and a steady microwave signal having an ultrahigh degree of spectral purity. The term "coupled optoelectronic" in the full name of such an apparatus signifies that its optical and electronic oscillations are coupled to each other in a single device. The present frequency-stabilization scheme is best described indirectly by describing the laboratory apparatus used to demonstrate it. The apparatus (see figure) includes a COEO that generates a comb-like optical spectrum, the various frequency components of which interfere, producing short optical pulses. This spectrum is centered at a nominal wavelength of 1,560 nm. The spectrum separation of this comb is about 10 GHz, as determined primarily by the length of an optical loop and the bandpass filter in the microwave feedback loop. The optical loop serves as microwave resonator having a very high value of the resonance quality factor (Q). The optical frequency of MLL is then stabilized by locking it to an atomic transition as described below. The COEO contains a tunable 1-nm band-pass optical filter and a piezoelectric-transducer (PZT) drum over which a stretch of fiber is wound. The 1-nm-wide pass band of the filter provides coarse tuning to overlap the frequency comb with the atomic transition frequency. Controlled stretching of the fiber by means of the PZT drum can be used in conjunction with temperature control for locking the laser frequency. To reference to an atomic resonance at 780 nm in this demonstration setup, the optical output of the COEO at 1,560 nm is fed through an erbium-doped-fiber amplifier (EDFA) to a frequency doubler in the form of a periodically poled lithium niobate (PPLN) crystal. The frequency-doubled output is combined with the output of a separate frequency-stabilized diode laser at a photodetector. As described thus far, the two 780-nm laser subsystems are nominally independent of each other and can, therefore, operate at different frequencies. Hence, at the photodetector, the two laser beams interfere, so that the output of the photodetector includes a beat note (a component at the difference between the two laser frequencies).

Persistence and distribution of 4-nonylphenol following repeated application to littoral enclosures

DOE Office of Scientific and Technical Information (OSTI.GOV)

Heinis, L.J.; Liber, K.; Tunell, R.L.

1999-03-01

The persistence and distribution of 4-nonylphenol (NP) were monitored for 440 d, following application to 18 littoral enclosures situated in a 2-ha mesotrophic pond near Duluth, Minnesota. Application was accomplished by subsurface, gravity-fed injection over a 20-d period, with a 2-d frequency, to achieve nominal aqueous concentrations of 0, 3, 30, 100, and 300 {micro}g/L. Mean maximum concentrations in the water over the 20-d application period ranged from 75.7 to 81.0% of nominal for the three highest treatment levels and was 181% of nominal at the lowest treatment level. Water was the major compartment, on a mass balance basis, formore » NP until 2 to 4 d after the application period, with a mean time to 50% dissipation (DT50) of 0.74 d and a mean time to 95% dissipation (DT95) of 13.8 d. 4-Nonylphenol partitioned to enclosure wall material, macrophytes, and sediment within 2 d of initial application. Macrophytes accumulated maximum NP concentrations of 11.5 and 139 mg/kg 1 to 2 d after the application period at the 30- and 300-{micro}g/L treatment levels, respectively. Mean DT50 and DT95 estimates of NP persistence in/on the macrophytes were 10.3 and 189 d, respectively. Sediment from the 30- and 300-{micro}g/L treatments accumulated maximum dry weight NP concentrations of 2.74 and 27.4 mg/kg, respectively within 20 to 48 d of the first application. The mean sediment porewater NP concentration was 18.6 {micro}g/L for the period 2 to 34 d after application 1 at the 300-{micro}g/L treatment. The sediment was the primary sink for NP 440 d after the initial application with a concentration of 1.97 mg/kg at the 300-{micro}g/L treatment. Mean sediment DT50 and DT95 values were 66.0 and 401 d, respectively, indicating a long-term persistence of NP. Ecocores collected 1 d after the final NP application did not show significant decreases in sediment NP concentration during a 55-d incubation period, corroborating the NP persistence observed in the littoral enclosures.« less

Wind turbine model and loop shaping controller design

NASA Astrophysics Data System (ADS)

Gilev, Bogdan

2017-12-01

A model of a wind turbine is evaluated, consisting of: wind speed model, mechanical and electrical model of generator and tower oscillation model. Model of the whole system is linearized around of a nominal point. By using the linear model with uncertainties is synthesized a uncertain model. By using the uncertain model is developed a H∞ controller, which provide mode of stabilizing the rotor frequency and damping the tower oscillations. Finally is simulated work of nonlinear system and H∞ controller.

Commutating Feed Assembly.

DTIC Science & Technology

1980-06-01

6 dB Stripline Couplers 29 3-4 Properties of Teflon -Fiberglass 30 5-1 Power Consumption for Various Motor Windings 47 5-2 Summary of Flanged 50-Ohm... spacing of 0.62A at the design frequency of 1.3 GHz. The diameter of such an array is nominally 180 inches. The chosen number of array elements is one-half...4 14 that required for a full-sized antenna with the same inter-element spacing . Azimuth patterns were computed for several circular array designs

The Impact of the HP 5071A on International Atomic Time. Appendix A

DTIC Science & Technology

1995-12-01

need still to be evaluated. Also in Figure 7, The upper and lower values for the two-way satellite time and frequency transfer ( TWSTFT ) technique are...typical performance stability observed between two sites remote to each other. The upper limit is dotted on the right end as a reminder that TWSTFT is not...not be as good as that shown, but would be nominally given by 1 nslr. The TWSTFT technique both transmits and receives, and cannot be used for

Nonlinear optics with coherent free electron lasers

NASA Astrophysics Data System (ADS)

Bencivenga, F.; Capotondi, F.; Mincigrucci, R.; Cucini, R.; Manfredda, M.; Pedersoli, E.; Principi, E.; Simoncig, A.; Masciovecchio, C.

2016-12-01

We interpreted the recent construction of free electron laser (FELs) facilities worldwide as an unprecedented opportunity to bring concepts and methods from the scientific community working with optical lasers into the domain of x-ray science. This motivated our efforts towards the realization of FEL-based wave-mixing applications. In this article we present new extreme ultraviolet transient grating (X-TG) data from vitreous SiO2, collected using two crossed FEL pulses (photon frequency 38 eV) to generate the X-TG and a phase matched optical probing pulse (photon frequency 3.1 eV). This experiment extends our previous investigation, which was carried out on a nominally identical sample using a different FEL photon frequency (45 eV) to excite the X-TG. The present data are featured by a peak intensity of the X-TG signal substantially larger than that previously reported and by slower modulations of the X-TG signal at positive delays. These differences could be ascribed to the different FEL photon energy used in the two experiments or to differences in the sample properties. A systematic X-TG study on the same sample as a function of the FEL wavelength is needed to draw a consistent conclusion. We also discuss how the advances in the performance of the FELs, in terms of generation of fully coherent photon pulses and multi-color FEL emission, may push the development of original experimental strategies to study matter at the femtosecond-nanometer time-length scales, with the unique option of element and chemical state specificity. This would allow the development of advanced experimental tools based on wave-mixing processes, which may have a tremendous impact in the study of a large array of phenomena, ranging from nano-dynamics in complex materials to charge and energy transfer processes.

Dynamic vehicle-track interaction in switches and crossings and the influence of rail pad stiffness - field measurements and validation of a simulation model

NASA Astrophysics Data System (ADS)

Pålsson, Björn A.; Nielsen, Jens C. O.

2015-06-01

A model for simulation of dynamic interaction between a railway vehicle and a turnout (switch and crossing, S&C) is validated versus field measurements. In particular, the implementation and accuracy of viscously damped track models with different complexities are assessed. The validation data come from full-scale field measurements of dynamic track stiffness and wheel-rail contact forces in a demonstrator turnout that was installed as part of the INNOTRACK project with funding from the European Union Sixth Framework Programme. Vertical track stiffness at nominal wheel loads, in the frequency range up to 20 Hz, was measured using a rolling stiffness measurement vehicle (RSMV). Vertical and lateral wheel-rail contact forces were measured by an instrumented wheel set mounted in a freight car featuring Y25 bogies. The measurements were performed for traffic in both the through and diverging routes, and in the facing and trailing moves. The full set of test runs was repeated with different types of rail pad to investigate the influence of rail pad stiffness on track stiffness and contact forces. It is concluded that impact loads on the crossing can be reduced by using more resilient rail pads. To allow for vehicle dynamics simulations at low computational cost, the track models are discretised space-variant mass-spring-damper models that are moving with each wheel set of the vehicle model. Acceptable agreement between simulated and measured vertical contact forces at the crossing can be obtained when the standard GENSYS track model is extended with one ballast/subgrade mass under each rail. This model can be tuned to capture the large phase delay in dynamic track stiffness at low frequencies, as measured by the RSMV, while remaining sufficiently resilient at higher frequencies.

Range and mission scheduling automation using combined AI and operations research techniques

NASA Technical Reports Server (NTRS)

Arbabi, Mansur; Pfeifer, Michael

1987-01-01

Ground-based systems for Satellite Command, Control, and Communications (C3) operations require a method for planning, scheduling and assigning the range resources such as: antenna systems scattered around the world, communications systems, and personnel. The method must accommodate user priorities, last minute changes, maintenance requirements, and exceptions from nominal requirements. Described are computer programs which solve 24 hour scheduling problems, using heuristic algorithms and a real time interactive scheduling process.

Dielectric properties of vertically aligned multi-walled carbon nanotubes in the terahertz and mid-infrared range

NASA Astrophysics Data System (ADS)

Thomson, Mark D.; Zouaghi, Wissem; Meng, Fanqi; Wiecha, Matthias M.; Rabia, Kaneez; Heinlein, Thorsten; Hussein, Laith; Babu, Deepu; Yadav, Sandeep; Engstler, Jörg; Schneider, Jörg J.; Nicoloso, Norbert; Rychetský, Ivan; Kužel, Petr; Roskos, Hartmut G.

2018-01-01

We investigate the broadband dielectric properties of vertically aligned, multi-wall carbon nanotubes (VACNT), over both the terahertz (THz) and mid-infrared spectral ranges. The nominally undoped, metallic VACNT samples are probed at normal incidence, i.e. the response is predominantly due to polarisation perpendicular to the CNT axis. A detailed comparison of various conductivity models and previously reported results is presented for the non-Drude behaviour we observe in the conventional THz range (up to 2.5 THz). Extension to the mid-infrared range reveals an absorption peak at \

Spontaneous Symmetry Breaking Facilitates Metal-to-Ligand Charge Transfer: A Quantitative Two-Photon Absorption Study of Ferrocene-phenyleneethynylene Oligomers.

PubMed

Mikhaylov, Alexander; Uudsemaa, Merle; Trummal, Aleksander; Arias, Eduardo; Moggio, Ivana; Ziolo, Ronald; Cooper, Thomas M; Rebane, Aleksander

2018-04-19

Change of the permanent molecular electric dipole moment, Δμ, in a series of nominally centrosymmetric and noncentrosymmteric ferrocene-phenyleneethynylene oligomers was estimated by measuring the two-photon absorption cross-section spectra of the lower energy metal-to-ligand charge-transfer transitions using femtosecond nonlinear transmission method and was found to vary in the range up to 12 D, with the highest value corresponding to the most nonsymmetric system. Calculations of the Δμ performed by the TD-DFT method show quantitative agreement with the experimental values and reveal that facile rotation of the ferrocene moieties relative to the organic ligand breaks the ground-state inversion symmetry in the nominally symmetric structures.

Experimental study of modification mechanism at a wear-resistant surfacing

NASA Astrophysics Data System (ADS)

Dema, R. R.; Amirov, R. N.; Kalugina, O. B.

2018-01-01

In the study, a simulation of the crystallization process was carried out for the deposition of the near-eutectic structure alloys with inoculants presence in order to reveal the regularities of the inoculant effect and parameters of the process mode simulating surfacing on the structure of the crystallization front and on the nucleation rate and kinetics of growth of equiaxed crystallites of primary phases occurring in the volume of the melt. The simulation technique of primary crystallization of alloys similar to eutectic alloys in the presence of modifiers is offered. The possibility of fully eutectic structure during surfacing of nominal hypereutectic alloys of type white cast irons in wide range of deviations from the nominal composition is revealed.

Conceptual design of an advanced Stirling conversion system for terrestrial power generation

NASA Technical Reports Server (NTRS)

1988-01-01

A free piston Stirling engine coupled to an electric generator or alternator with a nominal kWe power output absorbing thermal energy from a nominal 100 square meter parabolic solar collector and supplying electric power to a utility grid was identified. The results of the conceptual design study of an Advanced Stirling Conversion System (ASCS) were documented. The objectives are as follows: define the ASCS configuration; provide a manufacturability and cost evaluation; predict ASCS performance over the range of solar input required to produce power; estimate system and major component weights; define engine and electrical power condidtioning control requirements; and define key technology needs not ready by the late 1980s in meeting efficiency, life, cost, and with goalds for the ASCS.

Space shuttle: Heat transfer rate measurements on Convair booster (B-15B-2) and North American Rockwell orbiter (161B) at nominal Mach number of 8

NASA Technical Reports Server (NTRS)

Warmbrod, J. D.; Martindale, W. R.; Matthews, R. K.

1971-01-01

Plotted and tabulated data from the thin-skin thermocouple phase of an experimental test program are presented. These data are representative of three events of simulated flight and are described as booster-orbiter ascent heating data, booster reentry heating data, and orbiter reentry heating data. The test was conducted in a 50-inch hypersonic tunnel b at a nominal Mach number of 8 and free-stream Reynolds number range of 700,000 to 3,700,000 per foot. The model employed was a 0.009 scale replica of the Convair B-15B-2 booster and North American Rockwell 161B orbiter.

76 FR 51353 - Nominations for Membership on the Ocean Research Advisory Panel

Federal Register 2010, 2011, 2012, 2013, 2014

2011-08-18

... Leadership Council (NORLC), the governing body of the National Oceanographic Partnership Program (NOPP... extended expertise and experience in the field of ocean science and/or ocean resource management... balance a range of geographic and sector representation and experience. Applicants must be U.S. citizens...

A Call for Nominations of Quantitative High-Throughput Screening Assays from Relevant Human Toxicity Pathways

EPA Science Inventory

The National Research Council of the United States National Academies of Science has recently released a document outlining a long-range vision and strategy for transforming toxicity testing from largely whole animal-based testing to one based on in vitro assays. “Toxicity Testin...

Sentence Combining: A Rhetorical Perspective.

ERIC Educational Resources Information Center

Daiker, Donald A., Ed.; And Others

The 23 original essays on sentence combining in this volume range in focus from classroom methodology and effectiveness, through theoretical issues and syntactic constructions, to current issues in the field. The essays and their authors are as follows: (1) "The Role of the Elaborated Dominant Nominal in the Measurement of Conceptual and…

Fluorine follows water: Effect on electrical conductivity of silicate minerals by experimental constraints from phlogopite

NASA Astrophysics Data System (ADS)

Li, Yan; Jiang, Haotian; Yang, Xiaozhi

2017-11-01

Fluorine and hydroxyl groups are minor constituents of silicate minerals, and share a lot of similarities concerning their physical and chemical properties. Hydroxyl groups significantly enhance the electrical conductivity of many silicate minerals, and it is expected that fluorine would have a comparable effect. This, however, has never been documented quantitatively. Here we present experimental approaches on this issue, by investigating the electrical conductivity of phlogopite with a wide range of fluorine content (but with broadly similar contents for other major elements). Electrical conductivities of gem-quality single crystal phlogopites, with samples prepared along the same orientation (normal to the (0 0 1) plane), were determined at 1 GPa and 200-650 °C using an end-loaded piston cylinder apparatus and a Solartron-1260 Impedance/Gain Phase Analyzer over the frequency range of 106 to 0.1 Hz. The complex spectra usually show an arc in the high frequency range and a short tail in the low frequency range, which are caused by lattice conduction and electrode effects, respectively. The electrical conductivity increases with increasing fluorine content, and the main charge carriers are fluorine. The activation enthalpies are ∼180 to 200 kJ/mol, nearly independent of fluorine content. The conductivity is linearly proportional to the content of fluorine, with an exponent factor of ∼1. The results demonstrate that conduction by fluorine leads to very high electrical conductivity at high temperatures. The influence of fluorine on electrical conductivity may be compared to that of hydrogen in nominally anhydrous minerals. This, along with the close association of fluorine and hydroxyl groups in silicate minerals and their similar crystal-chemical behaviors, suggests a more general role of fluorine in enhancing the electrical conductivity of many silicate minerals. Fluorine-rich assemblages, e.g., phlogopite and amphibole, could be locally enriched in the upper mantle, and if they form connected networks as observed for some natural samples, regionally high electrical conductivities could be produced. It has been recently proposed that the transition zone is probably a major reservoir for fluorine in the mantle, due to the significant dissolution of fluorine in wadsleyite and ringwoodite and the coupled incorporation with hydroxyl groups. As such, geophysically-resolved high electrical conductivities in the transition zone may be accounted for by fluorine in the dominant minerals, rather than by hydroxyl groups. The results of this work would stimulate a wide scope of future studies on the deep fluorine cycle, the deep water cycle and the geodynamical properties of the mantle.

Wide bandwidth phase-locked loop circuit

NASA Technical Reports Server (NTRS)

Koudelka, Robert David (Inventor)

2005-01-01

A PLL circuit uses a multiple frequency range PLL in order to phase lock input signals having a wide range of frequencies. The PLL includes a VCO capable of operating in multiple different frequency ranges and a divider bank independently configurable to divide the output of the VCO. A frequency detector detects a frequency of the input signal and a frequency selector selects an appropriate frequency range for the PLL. The frequency selector automatically switches the PLL to a different frequency range as needed in response to a change in the input signal frequency. Frequency range hysteresis is implemented to avoid operating the PLL near a frequency range boundary.

SU-E-T-98: An Analysis of TG-51 Electron Beam Calibration Correction Factor Uncertainty

DOE Office of Scientific and Technical Information (OSTI.GOV)

Lee, P; Alvarez, P; Taylor, P

Purpose: To analyze the uncertainty of the TG-51 electron beam calibration correction factors for farmer type ion chambers currently used by institutions visited by IROC Houston. Methods: TG-51 calibration data were collected from 181 institutions visited by IROC Houston physicists for 1174 and 197 distinct electron beams from modern Varian and Elekta accelerators, respectively. Data collected and analyzed included ion chamber make and model, nominal energy, N{sub D,w}, I{sub 50}, R{sub 50}, k’R{sub 50}, d{sub ref}, P{sub gr} and pdd(d{sub ref}). k’R{sub 50} data for parallel plate chambers were excluded from the analysis. Results: Unlike photon beams, electron nominal energymore » is a poor indicator of the actual energy as evidenced by the range of R{sub 50} values for each electron beam energy (6–22MeV). The large range in R{sub 50} values resulted k’R{sub 50} values with a small standard deviation but large range between maximum value used and minimum value (0.001–0.029) used for a specific Varian nominal energy. Varian data showed more variability in k’R{sub 50} values than the Elekta data (0.001–0.014). Using the observed range of R{sub 50} values, the maximum spread in k’R{sub 50} values was determined by IROC Houston and compared to the spread of k’R{sub 50} values used in the community. For Elekta linacs the spreads were equivalent, but for Varian energies of 6 to 16MeV, the community spread was 2 to 6 times larger. Community P{sub gr} values had a much larger range of values for 6 and 9 MeV values than predicted. The range in Varian pdd(d{sub ref} ) used by the community for low energies was large, (1.4–4.9 percent), when it should have been very close to unity. Exradin, PTW Roos and PTW farmer chambers N{sub D,w} values showed the largest spread, ≥11 percent. Conclusion: While the vast majority of electron beam calibration correction factors used are accurate, there is a surprising spread in some of the values used.« less

Boundary layer and separation control on wings at low Reynolds numbers

NASA Astrophysics Data System (ADS)

Yang, Shanling

Results on boundary layer and separation control through acoustic excitation at low Re numbers are reported. The Eppler 387 profile is specifically chosen because of its pre-stall hysteresis and bi-stable state behavior in the transitional Re regime, which is a result of flow separation and reattachment. External acoustic forcing on the wing yields large improvements (more than 70%) in lift-to-drag ratio and flow reattachment at forcing frequencies that correlate with the measured anti-resonances in the wind tunnel. The optimum St/Re1/2 range for Re = 60,000 matches the proposed optimum range in the literature, but there is less agreement for Re = 40,000, which suggests that correct St scaling has not been determined. The correlation of aerodynamic improvements to wind tunnel resonances implies that external acoustic forcing is facility-dependent, which inhibits practical application. Therefore, internal acoustic excitation for the same wing profile is also pursued. Internal acoustic forcing is designed to be accomplished by embedding small speakers inside a custom-designed wing that contains many internal cavities and small holes in the suction surface. However, initial testing of this semi-porous wing model shows that the presence of the small holes in the suction surface completely transforms the aerodynamic performance by changing the mean chordwise separation location and causing an originally separated, low-lift state flow to reattach into a high-lift state. The aerodynamic improvements are not caused by the geometry of the small holes themselves, but rather by Helmholtz resonance that occurs in the cavities, which generate tones that closely match the intrinsic flow instabilities. Essentially, opening and closing holes in the suction surface of a wing, perhaps by digital control, can be used as a means of passive separation control. Given the similarity of wing-embedded pressure tap systems to Helmholtz resonators, particular attention must be given to the setup of pressure taps in wings in order to avoid acoustic resonance effects. Local acoustic forcing is achieved through the activation of internally embedded speakers in combination with thin diaphragms placed across the holes in the suction surface to eliminate Helmholtz resonance effects. Activating various speakers in different spanwise and chordwise distributions successfully controls local flow separation on the wing at Re = 40,000 and 60,000. The changes in aerodynamic performance differ from those observed through external acoustic forcing, indicating that internal acoustic forcing is facility-independent. Combining the effect of Helmholtz resonance and the effect of pure internal acoustic forcing yields a completely different set of performance improvements. Since the internal acoustic forcing studies in the literature did not separate these two effects, there is reason to question the validity of the true nominal performance of the wings in previously reported internal acoustic studies. Stability analysis is performed on experimental velocity profiles by means of a numerical Orr-Sommerfeld solver, which extracts the initially least stable frequencies in the boundary layer using parallel and 2-d flow assumptions. Velocity profiles of the E387 wing are chosen at a condition where acoustic excitation at various chordwise locations and frequencies promotes the originally separated, low-lift state flow into a reattached, high-lift state. Preliminary stability analysis of the flow at different chordwise stations for the wing in its nominal state (without acoustic excitation) indicates that the flow is initially stable. The least stable frequencies are found to be equal to, and sub harmonics of, the preferential acoustic forcing frequencies determined in experiments. However, potentially improper and oversimplified flow assumptions are most likely sources of inaccuracy since the Orr-Sommerfeld equation is not generally used for separated flows or for boundary layers that grow significantly over the chord length. The reported numerical results serve as a basis for further validation. (Abstract shortened by UMI.)

The MAX Statistic is Less Powerful for Genome Wide Association Studies Under Most Alternative Hypotheses.

PubMed

Shifflett, Benjamin; Huang, Rong; Edland, Steven D

2017-01-01

Genotypic association studies are prone to inflated type I error rates if multiple hypothesis testing is performed, e.g., sequentially testing for recessive, multiplicative, and dominant risk. Alternatives to multiple hypothesis testing include the model independent genotypic χ 2 test, the efficiency robust MAX statistic, which corrects for multiple comparisons but with some loss of power, or a single Armitage test for multiplicative trend, which has optimal power when the multiplicative model holds but with some loss of power when dominant or recessive models underlie the genetic association. We used Monte Carlo simulations to describe the relative performance of these three approaches under a range of scenarios. All three approaches maintained their nominal type I error rates. The genotypic χ 2 and MAX statistics were more powerful when testing a strictly recessive genetic effect or when testing a dominant effect when the allele frequency was high. The Armitage test for multiplicative trend was most powerful for the broad range of scenarios where heterozygote risk is intermediate between recessive and dominant risk. Moreover, all tests had limited power to detect recessive genetic risk unless the sample size was large, and conversely all tests were relatively well powered to detect dominant risk. Taken together, these results suggest the general utility of the multiplicative trend test when the underlying genetic model is unknown.

HF radar detection of infrasonic waves generated in the ionosphere by the 28 March 2005 Sumatra earthquake

NASA Astrophysics Data System (ADS)

Bourdillon, Alain; Occhipinti, Giovanni; Molinié, Jean-Philippe; Rannou, Véronique

2014-03-01

Surface waves generated by earthquakes create atmospheric waves detectable in the ionosphere using radio waves techniques: i.e., HF Doppler sounding, GPS and altimeter TEC measurements, as well as radar measurements. We present observations performed with the over-the-horizon (OTH) radar NOSTRADAMUS after the very strong earthquake (M=8.6) that occurred in Sumatra on March 28, 2005. An original method based on the analysis of the RTD (Range-Time-Doppler) image is suggested to identify the multi-chromatic ionospheric signature of the Rayleigh wave. The proposed method presents the advantage to preserve the information on the range variation and time evolution, and provides comprehensive results, as well as easy identification of the waves. In essence, a Burg algorithm of order 1 is proposed to compute the Doppler shift of the radar signal, resulting in sensitivity as good as obtained with higher orders. The multi-chromatic observation of the ionospheric signature of Rayleigh wave allows to extrapolate information coherent with the dispersion curve of Rayleigh waves, that is, we observe two components of the Rayleigh waves with estimated group velocities of 3.8 km/s and 3.6 km/s associated to 28 mHz (T~36 s) and 6.1 mHz (T~164 s) waves, respectively. Spectral analysis of the RTD image reveals anyway the presence of several oscillations at frequencies between 3 and 8 mHz clearly associated to the transfer of energy from the solid-Earth to the atmosphere, and nominally described by the normal modes theory for a complete planet with atmosphere. Oscillations at frequencies larger than 8 mHz are also observed in the spectrum but with smaller amplitudes. Particular attention is pointed out to normal modes 0S29 and 0S37 which are strongly involved in the coupling process. As the proposed method is frequency free, it could be used not only for detection of ionospheric perturbations induced by earthquakes, but also by other natural phenomena as well as volcanic explosions and particularly tsunamis, for future oceanic monitoring and tsunami warning systems.

The Safety of Intravenous Cyclophosphamide in the Treatment of Rheumatic Diseases.

PubMed

Woytala, Patryk J; Morgiel, Ewa; Łuczak, Anna; Czesak-Woytala, Katarzyna; Wiland, Piotr

2016-01-01

The therapeutic effects of cyclophosphamide (CP) in the treatment of systemic rheumatic diseases are related to its immune suppressive activity. However effective, the application of CP is restricted due to multiple adverse effects. This retrospective study was conducted to determine the frequency of adverse effects attributed to CP toxicity. The study involved 65 patients (17 male; 48 female) receiving intravenous CP between October 2007 and December 2010. The mean age at onset was 51.2 years (range 19-77 years). The most common diagnoses were systemic sclerosis (20), systemic lupus erythematosus (13) and vasculitis (13). The indications for treatment with CP were interstitial lung disease in the course of systemic diseases (33), vasculitis (24), glomerulonephritis (5) and changes in the central nervous system (3). The patients were administered 400-1000 mg CP in intravenous infusions at 2-16 week intervals, with the addition of sodium 2-sulfanylethanesulfonate (mesna) before and after each pulse. Out of 65 patients 40 (60%) reported adverse effects: infections in 24 (37%), nausea in 19 (29%), vomiting in 11 (17%), abdominal pain in 7 (11%) and pancytopenia in one, leading to cessation of the therapy. No association was found between the frequency of side effects and the treatment duration (p = 0.632), age (p = 0.852), diagnosis (p = 0.171) or nominal dose (p = 0.321). As knowledge about CP continues to increase, this medication remains a safe way to treat many rheumatic diseases.

Modeling and semi-active fuzzy control of magnetorheological elastomer-based isolator for seismic response reduction

NASA Astrophysics Data System (ADS)

Nguyen, Xuan Bao; Komatsuzaki, Toshihiko; Iwata, Yoshio; Asanuma, Haruhiko

2018-02-01

In this paper, a magnetorheological elastomer (MRE) based isolator was investigated to mitigate excessive vibrations in structures during seismic events. The primary objectives of this research are to propose a numerical model that expresses viscoelastic behaviors of the MRE and predict operation process of the MRE-based isolator for future design of isolator systems for various technical applications. Despite the simplicity in parameter definition in comparison to the conventional models, the proposed model works efficiently in a wide range of frequencies and amplitudes. The model consists of the following components: viscoelasticity of host MRE, magnetic field-induced property, nominal viscosity as well as high stiffness in low excitation frequency that are modeled in analogy with a standard linear solid model (Zener model), a stiffness variable spring, and a smooth Coulomb friction, respectively. Furthermore, a semi-active fuzzy controller was designed to enhance the performance of the isolator in suppressing structural vibrations. The control strategy was built to determine the command applied current. The controller is completely adequate for handling the nonlinearity of the isolator and works independently with the building structure. The efficiency of the MRE-based isolator was evaluated by the responses of the scaled building under seismic excitation. Numerical and experimental results show that the isolator accompanied with a fuzzy controller remarkably reduces the relative displacement and absolute acceleration of the scaled building compared to passive-off and passive-on cases.

High energy, single frequency, tunable laser source operating in burst mode for space based lidar applications

NASA Astrophysics Data System (ADS)

Cosentino, Alberto; Mondello, Alessia; Sapia, Adalberto; D'Ottavi, Alessandro; Brotini, Mauro; Gironi, Gianna; Suetta, Enrico

2017-11-01

This paper describes energetic, spatial, temporal and spectral characterization measurements of the Engineering Qualification Model (EQM) of the Laser Transmitter Assembly (TXA) used in the ALADIN instrument currently under development for the ESA ADM-AEOLUS mission (EADS Astrium as prime contractor for the satellite and the instrument). The EQM is equivalent to the Flight Model, with the exception of some engineering grade components. The Laser Transmitter Assembly, based on a diode pumped tripled Nd:YAG laser, is used to generate laser pulses at a nominal wavelength of 355 nm. This laser is operated in burst mode, with a pulse repetition cycle of 100 Hz during bursts. It is capable to operate in Single Longitudinal Mode and to be tuned over 25 GHz range. An internal "network" of sensors has been implemented inside the laser architecture to allow "in flight" monitoring of transmitter. Energy in excess of 100 mJ, with a spatial beam quality factor (M2) lower than 3, a spectral linewidth less than 50 MHz with a frequency stability better than 4 MHz on short term period have been measured on the EQM. Most of the obtained results are well within the expected values and match the Instrument requirements. They constitute an important achievement, showing the absence of major critical areas in terms of performance and the capability to obtain them in a rugged and compact structure suitable for space applications. The EQM will be submitted in the near future to an Environmental test campaign.

Photonic Bandgap (PBG) Shielding Technology

NASA Technical Reports Server (NTRS)

Bastin, Gary L.

2007-01-01

Photonic Bandgap (PBG) shielding technology is a new approach to designing electromagnetic shielding materials for mitigating Electromagnetic Interference (EM!) with small, light-weight shielding materials. It focuses on ground planes of printed wiring boards (PWBs), rather than on components. Modem PSG materials also are emerging based on planar materials, in place of earlier, bulkier, 3-dimensional PBG structures. Planar PBG designs especially show great promise in mitigating and suppressing EMI and crosstalk for aerospace designs, such as needed for NASA's Constellation Program, for returning humans to the moon and for use by our first human visitors traveling to and from Mars. Photonic Bandgap (PBG) materials are also known as artificial dielectrics, meta-materials, and photonic crystals. General PBG materials are fundamentally periodic slow-wave structures in I, 2, or 3 dimensions. By adjusting the choice of structure periodicities in terms of size and recurring structure spacings, multiple scatterings of surface waves can be created that act as a forbidden energy gap (i.e., a range of frequencies) over which nominally-conductive metallic conductors cease to be a conductor and become dielectrics. Equivalently, PBG materials can be regarded as giving rise to forbidden energy gaps in metals without chemical doping, analogous to electron bandgap properties that previously gave rise to the modem semiconductor industry 60 years ago. Electromagnetic waves cannot propagate over bandgap regions that are created with PBG materials, that is, over frequencies for which a bandgap is artificially created through introducing periodic defects

Fast range measurement of spot scanning proton beams using a volumetric liquid scintillator detector.

PubMed

Hui, CheukKai; Robertson, Daniel; Alsanea, Fahed; Beddar, Sam

2015-08-01

Accurate confirmation and verification of the range of spot scanning proton beams is crucial for correct dose delivery. Current methods to measure proton beam range using ionization chambers are either time-consuming or result in measurements with poor spatial resolution. The large-volume liquid scintillator detector allows real-time measurements of the entire dose profile of a spot scanning proton beam. Thus, liquid scintillator detectors are an ideal tool for measuring the proton beam range for commissioning and quality assurance. However, optical artefacts may decrease the accuracy of measuring the proton beam range within the scintillator tank. The purpose of the current study was to 1) develop a geometric calibration system to accurately calculate physical distances within the liquid scintillator detector, taking into account optical artefacts; and 2) assess the accuracy, consistency, and robustness of proton beam range measurement using the liquid scintillator detector with our geometric calibration system. The range of the proton beam was measured with the calibrated liquid scintillator system and was compared to the nominal range. Measurements were made on three different days to evaluate the setup robustness from day to day, and three sets of measurements were made for each day to evaluate the consistency from delivery to delivery. All proton beam ranges measured using the liquid scintillator system were within half a millimeter of the nominal range. The delivery-to-delivery standard deviation of the range measurement was 0.04 mm, and the day-to-day standard deviation was 0.10 mm. In addition to the accuracy and robustness demonstrated by these results when our geometric calibration system was used, the liquid scintillator system allowed the range of all 94 proton beams to be measured in just two deliveries, making the liquid scintillator detector a perfect tool for range measurement of spot scanning proton beams.

Fast range measurement of spot scanning proton beams using a volumetric liquid scintillator detector

PubMed Central

Hui, CheukKai; Robertson, Daniel; Alsanea, Fahed; Beddar, Sam

2016-01-01

Accurate confirmation and verification of the range of spot scanning proton beams is crucial for correct dose delivery. Current methods to measure proton beam range using ionization chambers are either time-consuming or result in measurements with poor spatial resolution. The large-volume liquid scintillator detector allows real-time measurements of the entire dose profile of a spot scanning proton beam. Thus, liquid scintillator detectors are an ideal tool for measuring the proton beam range for commissioning and quality assurance. However, optical artefacts may decrease the accuracy of measuring the proton beam range within the scintillator tank. The purpose of the current study was to 1) develop a geometric calibration system to accurately calculate physical distances within the liquid scintillator detector, taking into account optical artefacts; and 2) assess the accuracy, consistency, and robustness of proton beam range measurement using the liquid scintillator detector with our geometric calibration system. The range of the proton beam was measured with the calibrated liquid scintillator system and was compared to the nominal range. Measurements were made on three different days to evaluate the setup robustness from day to day, and three sets of measurements were made for each day to evaluate the consistency from delivery to delivery. All proton beam ranges measured using the liquid scintillator system were within half a millimeter of the nominal range. The delivery-to-delivery standard deviation of the range measurement was 0.04 mm, and the day-to-day standard deviation was 0.10 mm. In addition to the accuracy and robustness demonstrated by these results when our geometric calibration system was used, the liquid scintillator system allowed the range of all 94 proton beams to be measured in just two deliveries, making the liquid scintillator detector a perfect tool for range measurement of spot scanning proton beams. PMID:27274863

An actively mode-locked fiber laser for sampling in a wide-bandwidth opto-electronic analog-to-digital converter

NASA Astrophysics Data System (ADS)

Powers, John P.; Pace, Phillip E.

2008-02-01

We have designed, built and tested an actively mode-locked fiber laser, operating at 1550 nm, for use as the sampling waveform in an opto-electronic analog-to-digital converter (ADC). Analysis shows that, in order to digitize a 10-GHz signal to 10 bits of resolution, the sampling pulsewidth must be less than 2.44 ps, the RMS timing jitter must be below 31.0 fs, and the RMS amplitude jitter must be below 0.195%. Fiber lasers have proven to have the capability to narrowly exceed these operating requirements. The fiber laser is a "sigma" laser consisting of Er-doped gain medium, dispersion-compensating fiber, nonlinear fiber, a Faraday rotation mirror, polarization-maintaining fiber and components, and diode pump lasers. The active mode-locking is achieved by a Mach-Zehnder interferometer modulator, driven by a frequency synthesizer operating at the desired sampling rate. A piezo-electric element is used in a feedback control loop to stabilize the output PRF against environmental changes. Measurements of the laser output revealed the maximum nominal PRF to be 16 GHz, the nominal pulsewidth to be 7.2 ps, and the nominal RNS timing jitter to be 386 fs. Incorporating this laser into a sampling ADC would allow us to sample a 805-MHz bandwidth signal to a resolution of 10 bits as limited by timing jitter. Techniques to reduce the timing-jitter bottleneck are discussed.

Parametric excitation of tire-wheel assemblies by a stiffness non-uniformity

NASA Astrophysics Data System (ADS)

Stutts, D. S.; Krousgrill, C. M.; Soedel, W.

1995-01-01

A simple model of the effect of a concentrated radial stiffness non-uniformity in a passenger car tire is presented. The model treats the tread band of the tire as a rigid ring supported on a viscoelastic foundation. The distributed radial stiffness is lumped into equivalent horizontal (fore-and-aft) and vertical stiffnesses. The concentrated radial stiffness non-uniformity is modeled by treating the tread band as fixed, and the stiffness non-uniformity as rotating around it at the nominal angular velocity of the wheel. Due to loading, the center of mass of the tread band ring model is displaced upward with respect to the wheel spindle and, therefore, the rotating stiffness non-uniformity is alternately compressed and stretched through one complete rotation. This stretching and compressing of the stiffness non-uniformity results in force transmission to the wheel spindle at twice the nominal angular velocity in frequency, and therefore, would excite a given resonance at one-half the nominal angular wheel velocity that a mass unbalance would. The forcing produced by the stiffness non-uniformity is parametric in nature, thus creating the possibility of parametric resonance. The basic theory of the parametric resonance is explained, and a parameter study using derived lumped parameters based on a typical passenger car tire is performed. This study revealed that parametric resonance in passenger car tires, although possible, is unlikely at normal highway speeds as predicted by this model unless the tire is partially deflated.

Unusual ISS Rate Signature

NASA Technical Reports Server (NTRS)

Laible, Michael R.

2011-01-01

On November 23, 2011 International Space Station Guidance, Navigation, and Control reported unusual pitch rate disturbance. These disturbances were an order of magnitude greater than nominal rates. The Loads and Dynamics team was asked to review and analyze current accelerometer data to investigate this disturbance. This paper will cover the investigation process under taken by the Loads and Dynamics group. It will detail the accelerometers used and analysis performed. The analysis included performing Frequency Fourier Transform of the data to identify the mode of interest. This frequency data is then reviewed with modal analysis of the ISS system model. Once this analysis is complete and the disturbance quantified, a forcing function was produced to replicate the disturbance. This allows the Loads and Dynamics team to report the load limit values for the 100's of interfaces on the ISS.

Sinusoidal Siemens star spatial frequency response measurement errors due to misidentified target centers

DOE PAGES

Birch, Gabriel Carisle; Griffin, John Clark

2015-07-23

Numerous methods are available to measure the spatial frequency response (SFR) of an optical system. A recent change to the ISO 12233 photography resolution standard includes a sinusoidal Siemens star test target. We take the sinusoidal Siemens star proposed by the ISO 12233 standard, measure system SFR, and perform an analysis of errors induced by incorrectly identifying the center of a test target. We show a closed-form solution for the radial profile intensity measurement given an incorrectly determined center and describe how this error reduces the measured SFR of the system. As a result, using the closed-form solution, we proposemore » a two-step process by which test target centers are corrected and the measured SFR is restored to the nominal, correctly centered values.« less

Dynamic analysis of a flexible spacecraft with rotating components. Volume 1: Analytical developments

NASA Technical Reports Server (NTRS)

Bodley, C. S.; Devers, A. D.; Park, A. C.

1975-01-01

Analytical procedures and digital computer code are presented for the dynamic analysis of a flexible spacecraft with rotating components. Topics, considered include: (1) nonlinear response in the time domain, and (2) linear response in the frequency domain. The spacecraft is assumed to consist of an assembly of connected rigid or flexible subassemblies. The total system is not restricted to a topological connection arrangement and may be acting under the influence of passive or active control systems and external environments. The analytics and associated digital code provide the user with the capability to establish spacecraft system nonlinear total response for specified initial conditions, linear perturbation response about a calculated or specified nominal motion, general frequency response and graphical display, and spacecraft system stability analysis.

Effect of bird maneuver on frequency-domain helicopter EM response

USGS Publications Warehouse

Fitterman, D.V.; Yin, C.

2004-01-01

Bird maneuver, the rotation of the coil-carrying instrument pod used for frequency-domain helicopter electromagnetic surveys, changes the nominal geometric relationship between the bird-coil system and the ground. These changes affect electromagnetic coupling and can introduce errors in helicopter electromagnetic, (HEM) data. We analyze these effects for a layered half-space for three coil configurations: vertical coaxial, vertical coplanar, and horizontal coplanar. Maneuver effect is shown to have two components: one that is purely geometric and another that is inductive in nature. The geometric component is significantly larger. A correction procedure is developed using an iterative approach that uses standard HEM inversion routines. The maneuver effect correction reduces inversion misfit error and produces laterally smoother cross sections than obtained from uncorrected data. ?? 2004 Society of Exploration Geophysicists. All rights reserved.

Sleuthing the MSL EDL performance from an X band carrier perspective

NASA Astrophysics Data System (ADS)

Oudrhiri, Kamal; Asmar, Sami; Estabrook, Polly; Kahan, Daniel; Mukai, Ryan; Ilott, Peter; Schratz, Brian; Soriano, Melissa; Finley, Susan; Shidner, Jeremy

During the Entry, Descent, and Landing (EDL) of NASA's Mars Science Laboratory (MSL), or Curiosity, rover to Gale Crater on Mars on August 6, 2012 UTC, the rover transmitted an X-band signal composed of carrier and tone frequencies and a UHF signal modulated with an 8kbps data stream. During EDL, the spacecraft's orientation is determined by its guidance and mechanical subsystems to ensure that the vehicle land safely at its destination. Although orientation to maximize telecom performance is not possible, antennas are especially designed and mounted to provide the best possible line of sight to Earth and to the Mars orbiters supporting MSL's landing. The tones and data transmitted over these links are selected carefully to reflect the most essential parameters of the vehicle's state and the performance of the EDL subsystems for post-EDL reconstruction should no further data transmission from the vehicle be possible. This paper addresses the configuration of the X band receive system used at NASA / JPL's Deep Space Network (DSN) to capture the signal spectrum of MSL's X band carrier and tone signal, examines the MSL vehicle state information obtained from the X band carrier signal only and contrasts the Doppler-derived information against the post-EDL known vehicle state. The paper begins with a description of the MSL EDL sequence of events and discusses the impact of the EDL maneuvers such as guided entry, parachute deploy, and powered descent on the frequency observables expected at the DSN. The range of Doppler dynamics possible is derived from extensive 6 Degrees-Of-Freedom (6 DOF) vehicle state calculations performed by MSL's EDL simulation team. The configuration of the DSN's receive system, using the Radio Science Receivers (RSR) to perform open-loop recording for both for nominal and off-nominal EDL scenarios, is detailed. Expected signal carrier power-to-noise levels during EDL are shown and their impact on signal detection is considered. Particula- attention is given to the selection of the appropriate RSR processing bandwidths and to its configuration for real-time signal detection. The X-band carrier frequency obtained through post-processing of the open-loop recorded spectrum is given. Detection of spacecraft status and completion of key vehicle events through their Doppler signature is discussed and illustrated. This Doppler-derived information is compared against the very accurate vehicle data obtained post-EDL via MSL's UHF radio subsystem. The paper concludes with a discussion on the advantages and disadvantages of transmitting the X-band carrier and tone signal in the general context of EDL communications and lessons learned for future missions with EDL sequences are given.

Sleuthing the MSL EDL Performance from an X Band Carrier Perspective

NASA Technical Reports Server (NTRS)

Oudrhiri, Kamal; Asmar, Sami; Estabrook, Polly; Kahan, Daniel; Mukai, Ryan; Ilott, Peter; Schratz, Brian; Soriano, Melissa; Finley, Susan; Shidner, Jeremy

2013-01-01

During the Entry, Descent, and Landing (EDL) of NASA's Mars Science Laboratory (MSL), or Curiosity, rover to Gale Crater on Mars on August 6, 2012 UTC, the rover transmitted an X-band signal composed of carrier and tone frequencies and a UHF signal modulated with an 8kbps data stream. During EDL, the spacecraft's orientation is determined by its guidance and mechanical subsystems to ensure that the vehicle land safely at its destination. Although orientation to maximize telecom performance is not possible, antennas are especially designed and mounted to provide the best possible line of sight to Earth and to the Mars orbiters supporting MSL's landing. The tones and data transmitted over these links are selected carefully to reflect the most essential parameters of the vehicle's state and the performance of the EDL subsystems for post-EDL reconstruction should no further data transmission from the vehicle be possible. This paper addresses the configuration of the X band receive system used at NASA / JPL's Deep Space Network (DSN) to capture the signal spectrum of MSL's X band carrier and tone signal, examines the MSL vehicle state information obtained from the X band carrier signal only and contrasts the Doppler-derived information against the post-EDL known vehicle state. The paper begins with a description of the MSL EDL sequence of events and discusses the impact of the EDL maneuvers such as guided entry, parachute deploy, and powered descent on the frequency observables expected at the DSN. The range of Doppler dynamics possible is derived from extensive 6 Degrees-Of-Freedom (6 DOF) vehicle state calculations performed by MSL's EDL simulation team. The configuration of the DSN's receive system, using the Radio Science Receivers (RSR) to perform open-loop recording for both for nominal and off-nominal EDL scenarios, is detailed. Expected signal carrier power-to-noise levels during EDL are shown and their impact on signal detection is considered. Particular attention is given to the selection of the appropriate RSR processing bandwidths and to its configuration for real-time signal detection. The X-band carrier frequency obtained through post-processing of the open-loop recorded spectrum is given. Detection of spacecraft status and completion of key vehicle events through their Doppler signature is discussed and illustrated. This Doppler-derived information is compared against the very accurate vehicle data obtained post-EDL via MSL's UHF radio subsystem. The paper concludes with a discussion on the advantages and disadvantages of transmitting the X-band carrier and tone signal in the general context of EDL communications and lessons learned for future missions with EDL sequences are given

LANDSAT-1 and LANDSAT-2 flight evaluation report, 23 July - 23 October 1976

NASA Technical Reports Server (NTRS)

1976-01-01

The LANDSAT-1 spacecraft was launched from the Western Test Range on 23 July 1972, at 18:08:06.508Z. The launch and orbital injection phase of the space flight was nominal, and deployment of the spacecraft followed predictions. Performance evaluation of the spacecraft is presented.

Research in Arts Education: A Federal Chapter.

ERIC Educational Resources Information Center

Murphy, Judith; Jones, Lonna

This document provides an overview of art education research funded by the Arts and Humanities Program (AHP) from 1965-70. Several dozen research and development projects, selected from among the more than 200 initiated during this period, are analyzed to indicate the wide range of scope and funding, nominal success or failure, distribution among…

Photogrammetry Of A Parabolic Antenna

NASA Technical Reports Server (NTRS)

Merrick, W. D.; Lansing, F. L.; Stoller, F. W.; Lobb, V. B.

1988-01-01

Surface measured with accuracy better than 10 to the negative fifth power times diameter. Report describes use of advanced close-range photogrammetry to determine deviations of 34-m-diameter antenna main reflector and subreflector from nominal paraboloidal shapes. Measurements enable removal of linear offsets and angular misalignments of subreflector, with consequent increase of 4 percent in aperture efficiency.

The effect of aluminum on the work hardening and wear resistance of hadfield manganese steel

NASA Astrophysics Data System (ADS)

Zuidema, B. K.; Subramanyam, D. K.; Leslie, W. C.

1987-09-01

A study has been made of the work-hardening and wear resistance of aluminum-modified Hadfield manganese steels ranging in composition from 1.00 to 1.75 Pct carbon and from 0.0 to 4.0 Pct aluminum. Aluminum additions reduced carbon activity and diffusivity in austenites of Hadfield’s composition, increasing the metastable solubility of carbon in Hadfield steel. Aluminum additions inhibited mechanical twinning and, by inference, increased the stacking fault energy of austenite. Increasing carbon in solution in austenite expanded the temperature range over which dynamic strain aging and rapid work hardening occurred. Simultaneous aluminum additions and increased carbon content increased the work-hardening rate and high-stress abrasion resistance of Hadfield steel, but there was an optimum aluminum content beyond which both declined. Maximum work-hardening rate was exhibited by an alloy containing nominally 1.75 Pct C, 13.5 Pct Mn, and 1.3 Pct Al. Improved high-stress abrasion resistance was also found in an alloy containing nominally 1.00 Pct C, 13.5 Pct Mn, and 4.0 Pct Al.

Determination of the Effective Detector Area of an Energy-Dispersive X-Ray Spectrometer at the Scanning Electron Microscope Using Experimental and Theoretical X-Ray Emission Yields.

PubMed

Procop, Mathias; Hodoroaba, Vasile-Dan; Terborg, Ralf; Berger, Dirk

2016-12-01

A method is proposed to determine the effective detector area for energy-dispersive X-ray spectrometers (EDS). Nowadays, detectors are available for a wide range of nominal areas ranging from 10 up to 150 mm2. However, it remains in most cases unknown whether this nominal area coincides with the "net active sensor area" that should be given according to the related standard ISO 15632, or with any other area of the detector device. Moreover, the specific geometry of EDS installation may further reduce a given detector area. The proposed method can be applied to most scanning electron microscope/EDS configurations. The basic idea consists in a comparison of the measured count rate with the count rate resulting from known X-ray yields of copper, titanium, or silicon. The method was successfully tested on three detectors with known effective area and applied further to seven spectrometers from different manufacturers. In most cases the method gave an effective area smaller than the area given in the detector description.

Sonic Booms in Atmospheric Turbulence (SonicBAT) Ground Measurements in a Hot Desert Climate

NASA Technical Reports Server (NTRS)

Haering, Edward A., Jr.

2017-01-01

The Sonic Booms in Atmospheric Turbulence (SonicBAT) Project flew a series of 20 F-18 flights with 69 supersonic passes at Edwards Air Force Base in July 2016 to quantify the effect of atmospheric turbulence on sonic booms. Most of the passes were at a pressure altitude of 32,000 feet and a Mach number of 1.4, yielding a nominal sonic boom overpressure of 1.6 pounds per square foot. Atmospheric sensors such as GPS sondeballoons, Sonic Detection and Ranging (SODAR) acoustic sounders, and ultrasonic anemometers were used to characterize the turbulence state of the atmosphere for each flight. Spiked signatures in excess of 7 pounds per square foot were measured at some locations, as well as rounded sonic-boom signatures with levels much lower than the nominal. This presentation will quantify the range of overpressure and Perceived Level of the sonic boom as a function of turbulence parameters, and also present the spatial variation of these quantities over the array. Comparison with historical data will also be shown.

77 FR 52330 - Request for Additional Nominations of Candidates for the EPA's Science Advisory Board (SAB...

Federal Register 2010, 2011, 2012, 2013, 2014

2012-08-29

... person or organization may nominate qualified persons to be considered for appointment to this advisory committee. Individuals may self-nominate. Nominations should be submitted in electronic format (preferred) following the instructions for ``Nominating Experts to the Chemical Assessment Advisory Committee'' provided...

76 FR 71561 - Request for Nominations of Candidates to the EPA's Science Advisory Board (SAB) Chemical...

Federal Register 2010, 2011, 2012, 2013, 2014

2011-11-18

... nominate qualified persons to be considered for appointment to this advisory committee. Individuals may self-nominate. Nominations should be submitted in electronic format (preferred) following the instructions for ``Nominating Experts to the Chemical Assessment Advisory Committee'' provided on the SAB Web...

Nominalizations in Spanish. Studies in Linguistics and Language Learning, Volume V.

ERIC Educational Resources Information Center

Falk, Julia Sableski

Using methods developed in transformational generative grammar, three types of nominal constructions in Spanish are treated in this paper: Fact nominalizations ("[El] Escribir es agradable"), Manner nominalizations ("El tocar [de la mujer] es agradable"), and Abstract noun nominalizations ("La construccion rapida de esta escuela es dudosa"). While…

Development of the Orion Crew Module Static Aerodynamic Database. Par 2; Supersonic/Subsonic

NASA Technical Reports Server (NTRS)

Bibb, Karen L.; Walker, Eric L.; Brauckmann, Gregory J.; Robinson, Phil

2011-01-01

This work describes the process of developing the nominal static aerodynamic coefficients and associated uncertainties for the Orion Crew Module for Mach 8 and below. The database was developed from wind tunnel test data and computational simulations of the smooth Crew Module geometry, with no asymmetries or protuberances. The database covers the full range of Reynolds numbers seen in both entry and ascent abort scenarios. The basic uncertainties were developed as functions of Mach number and total angle of attack from variations in the primary data as well as computations at lower Reynolds numbers, on the baseline geometry, and using different flow solvers. The resulting aerodynamic database represents the Crew Exploration Vehicle Aerosciences Project's best estimate of the nominal aerodynamics for the current Crew Module vehicle.

Contingency plans for the ISEE-3 libration-point mission

NASA Technical Reports Server (NTRS)

Dunham, D. W.

1979-01-01

During the planning stage of the International Sun-Earth Explorer-3 (ISEE-3) mission, a recovery strategy was developed in case the Delta rocket underperformed during the launch phase. If a large underburn had occurred, the ISEE-3 spacecraft would have been allowed to complete one revolution of its highly elliptical earth orbit. The recovery plan called for a maneuver near perigee to increase the energy of the off-nominal orbit; a relatively small second maneuver would then insert the spacecraft into a new transfer trajectory toward the desired halo orbit target, and a third maneuver would place the spacecraft in the halo orbit. Results of the study showed that a large range of underburns could be corrected for a total nominal velocity deviation cost within the ISEE-3 fuel budget.

Split-Block Waveguide Polarization Twist for 220 to 325 GHz

NASA Technical Reports Server (NTRS)

Ward, John; Chattopadhyay, Goutam

2008-01-01

A split-block waveguide circuit that rotates polarization by 90 has been designed with WR-3 input and output waveguides, which are rectangular waveguides used for a nominal frequency range of 220 to 325 GHz. Heretofore, twisted rectangular waveguides equipped with flanges at the input and output have been the standard means of rotating the polarizations of guided microwave signals. However, the fabrication and assembly of such components become difficult at high frequency due to decreasing wavelength, such that twisted rectangular waveguides become impractical at frequencies above a few hundred gigahertz. Conventional twisted rectangular waveguides are also not amenable to integration into highly miniaturized subassemblies of advanced millimeter- and submillimeter-wave detector arrays now undergoing development. In contrast, the present polarization- rotating waveguide can readily be incorporated into complex integrated waveguide circuits such as miniaturized detector arrays fabricated by either conventional end milling of metal blocks or by deep reactive ion etching of silicon blocks. Moreover, the present split-block design can be scaled up in frequency to at least 5 THz. The main step in fabricating a splitblock polarization-rotating waveguide of the present design is to cut channels having special asymmetrically shaped steps into mating upper and lower blocks (see Figure 1). The dimensions of the steps are chosen to be consistent with the WR-3 waveguide cross section, which is 0.864 by 0.432 mm. The channels are characterized by varying widths with constant depths of 0.432, 0.324, and 0.216 mm and by relatively large corner radii to facilitate fabrication. The steps effect both a geometric transition and the corresponding impedance-matched electromagnetic-polarization transition between (1) a WR-3 rectangular waveguide oriented with the electric field vector normal to the block mating surfaces and (2) a corresponding WR-3 waveguide oriented with its electric field vector parallel to the mating surfaces of the blocks. A prototype has been built and tested. Figure 2 presents test results indicative of good performance over nearly the entire WR-3 waveguide frequency band.

High-Frequency Ultrasonic Imaging of the Anterior Segment Using an Annular Array Transducer

PubMed Central

Silverman, Ronald H.; Ketterling, Jeffrey A.; Coleman, D. Jackson

2006-01-01

Objective Very-high-frequency (>35 MHz) ultrasound (VHFU) allows imaging of anterior segment structures of the eye with a resolution of less than 40-μm. The low focal ratio of VHFU transducers, however, results in a depth-of-field (DOF) of less than 1-mm. Our aim was to develop a high-frequency annular array transducer for ocular imaging with improved DOF, sensitivity and resolution compared to conventional transducers. Design Experimental Study Participants Cadaver eyes, ex vivo cow eyes, in vivo rabbit eyes. Methods A spherically curved annular array ultrasound transducer was fabricated. The array consisted of five concentric rings of equal area, had an overall aperture of 6 mm and a geometric focus of 12 mm. The nominal center frequency of all array elements was 40 MHz. An experimental system was designed in which a single array element was pulsed and echo data recorded from all elements. By sequentially pulsing each element, echo data were acquired for all 25 transmit/receive annuli combinations. The echo data were then synthetically focused and composite images produced. Transducer operation was tested by scanning a test object consisting of a series of 25-μm diameter wires spaced at increasing range from the transducer. Imaging capabilities of the annular array were demonstrated in ex vivo bovine, in vivo rabbit and human cadaver eyes. Main Outcome Measures Depth of field, resolution and sensitivity. Results The wire scans verified the operation of the array and demonstrated a 6.0 mm DOF compared to the 1.0 mm DOF of a conventional single-element transducer of comparable frequency, aperture and focal length. B-mode images of ex vivo bovine, in vivo rabbit and cadaver eyes showed that while the single-element transducer had high sensitivity and resolution within 1–2 mm of its focus, the array with synthetic focusing maintained this quality over a 6 mm DOF. Conclusion An annular array for high-resolution ocular imaging has been demonstrated. This technology offers improved depth-of-field, sensitivity and lateral resolution compared to single-element fixed focus transducers currently used for VHFU imaging of the eye. PMID:17141314

High-frequency ultrasonic imaging of the anterior segment using an annular array transducer.

PubMed

Silverman, Ronald H; Ketterling, Jeffrey A; Coleman, D Jackson

2007-04-01

Very high-frequency ultrasound (VHFU; >35 megahertz [MHz]) allows imaging of anterior segment structures of the eye with a resolution of less than 40 microm. The low focal ratio of VHFU transducers, however, results in a depth of field (DOF) of less than 1 mm. The aim was to develop a high-frequency annular array transducer for ocular imaging with improved DOF, sensitivity, and resolution compared with conventional transducers. Experimental study. Cadaver eyes, ex vivo cow eyes, in vivo rabbit eyes. A spherically curved annular array ultrasound transducer was fabricated. The array consisted of 5 concentric rings of equal area, had an overall aperture of 6 mm, and a geometric focus of 12 mm. The nominal center frequency of all array elements was 40 MHz. An experimental system was designed in which a single array element was pulsed and echo data were recorded from all elements. By sequentially pulsing each element, echo data were acquired for all 25 transmit-and-receive annuli combinations. The echo data then were focused synthetically and composite images were produced. Transducer operation was tested by scanning a test object consisting of a series of 25-microm diameter wires spaced at increasing range from the transducer. Imaging capabilities of the annular array were demonstrated in ex vivo bovine, in vivo rabbit, and human cadaver eyes. Depth of field, resolution, and sensitivity. The wire scans verified the operation of the array and demonstrated a 6.0-mm DOF, compared with the 1.0-mm DOF of a conventional single-element transducer of comparable frequency, aperture, and focal length. B-mode images of ex vivo bovine, in vivo rabbit, and cadaver eyes showed that although the single-element transducer had high sensitivity and resolution within 1 to 2 mm of its focus, the array with synthetic focusing maintained this quality over a 6-mm DOF. An annular array for high-resolution ocular imaging has been demonstrated. This technology offers improved DOF, sensitivity, and lateral resolution compared with single-element fixed focus transducers currently used for VHFU imaging of the eye.

The medial prefrontal cortex exhibits money illusion

PubMed Central

Weber, Bernd; Rangel, Antonio; Wibral, Matthias; Falk, Armin

2009-01-01

Behavioral economists have proposed that money illusion, which is a deviation from rationality in which individuals engage in nominal evaluation, can explain a wide range of important economic and social phenomena. This proposition stands in sharp contrast to the standard economic assumption of rationality that requires individuals to judge the value of money only on the basis of the bundle of goods that it can buy—its real value—and not on the basis of the actual amount of currency—its nominal value. We used fMRI to investigate whether the brain's reward circuitry exhibits money illusion. Subjects received prizes in 2 different experimental conditions that were identical in real economic terms, but differed in nominal terms. Thus, in the absence of money illusion there should be no differences in activation in reward-related brain areas. In contrast, we found that areas of the ventromedial prefrontal cortex (vmPFC), which have been previously associated with the processing of anticipatory and experienced rewards, and the valuation of goods, exhibited money illusion. We also found that the amount of money illusion exhibited by the vmPFC was correlated with the amount of money illusion exhibited in the evaluation of economic transactions. PMID:19307555

Plasmonic behaviour of sputtered Au nanoisland arrays

NASA Astrophysics Data System (ADS)

Tvarožek, V.; Szabó, O.; Novotný, I.; Kováčová, S.; Škriniarová, J.; Šutta, P.

2017-02-01

The specificity of the formation of Au sputtered nanoisland arrays (NIA) on a glass substrate or on a ZnO thin film doped by Ga is demonstrated. Statistical analysis of morphology images (SEM, AFM) exhibited the Log-normal distribution of the size (area) of nanoislands-their modus AM varied from 8 to 328 nm2 depending on the sputtering power density, which determined the nominal thicknesses in the range of 2-8 nm. Preferential polycrystalline texture (111) of Au NIA increased with the power density and after annealing. Transverse localised surface plasmonic resonance (LSPR; evaluated by transmission UV-vis spectroscopy) showed the red shift of the extinction peaks (Δl ≤ 100 nm) with an increase of the nominal thickness, and the blue shift (Δλ ≤ -65 nm) after annealing of Au NIA. The plasmonic behaviour of Au NIA was described by modification of a size-scaling universal model using the nominal thin film thickness as a technological scaling parameter. Sputtering of a Ti intermediate adhesive ultrathin film between the glass substrate and gold improves the adhesion of Au nanoislands as well as supporting the formation of more defined Au NIA structures of smaller dimensions.

Theory versus experiment for the rotordynamic coefficients of annular gas seals. Part 1: Test facility and apparatus

NASA Technical Reports Server (NTRS)

Childs, D. W.; Nelson, C. E.; Nicks, C.; Scharrer, J. K.; Elrod, D.; Hale, K.

1983-01-01

A facility and apparatus are described for determining the rotordynamic coefficients and leakage characteristics of annular gas seals. The apparatus has a current top speed of 8000 cpm with a nominal seal diameter of 15.24 cmn (6 in). The air supply unit yields a seal pressure ratio of approximately 7. An external shaker is used to excite the test rotor. The capability to independently calculate all rotordynamic coefficients at a given operating condition with one excitation frequency are discussed.

Balancing fast-rotating parts of hand-held machine drive

NASA Astrophysics Data System (ADS)

Korotkov, V. S.; Sicora, E. A.; Nadeina, L. V.; Yongzheng, Wang

2018-03-01

The article considers the issues related to the balancing of fast rotating parts of the hand-held machine drive including a wave transmission with intermediate rolling elements, which is constructed on the basis of the single-phase collector motor with a useful power of 1 kW and a nominal rotation frequency of 15000 rpm. The forms of balancers and their location are chosen. The method of balancing is described. The scheme for determining of residual unbalance in two correction planes is presented. Measurement results are given in tables.

Noise reduction and control in mode-locked semiconductor diode lasers for use in next-generation all-optical analog-to-digital converters

NASA Astrophysics Data System (ADS)

DePriest, Christopher M.; Abeles, Joseph H.; Braun, Alan; Delfyett, Peter J., Jr.

2000-07-01

External-cavity, actively-modelocked semiconductor diode lasers (SDLs) have proven to be attractive candidates for forming the backbone of next-generation analog-to-digital converters (ADCs), which are currently being developed to sample signals at repetition rates exceeding several GHz with up to 12 bits of digital resolution. Modelocked SDLs are capable of producing waveform-sampling pulse trains with very low temporal jitter (phase noise) and very small fluctuations in pulse height (amplitude noise)--two basic conditions that must be met in order for high-speed ADCs to achieve projected design goals. Single-wavelength modelocked operation (at nominal repetition frequencies of 400 MHz) has produced pulse trains with very low amplitude noise (approximately 0.08%), and the implementation of a phase- locked-loop has been effective in reducing the system's low- frequency phase noise (RMS timing jitter for offset frequencies between 10 Hz and 10 kHz has been reduced from 240 fs to 27 fs).

Electron Acceleration and Ionization Production in High-Power Heating Experiments at HAARP

NASA Astrophysics Data System (ADS)

Mishin, E. V.; Pedersen, T.

2012-12-01

Recent ionospheric modification experiments with the 3.6 MW transmitter at the High Frequency Active Auroral Research Program (HAARP) facility in Alaska led to discovery of artificial ionization descending from the nominal interaction altitude in the background F-region ionosphere by ~60-80 km. Artificial ionization production is indicated by significant 427.8 nm emissions from the 1st negative band of N2+ and the appearance of transmitter-induced bottomside traces in ionosonde data during the periods of most intense optical emissions. However, the exact mechanisms producing the artificial plasmas remain to be determined. Yet the only existing theoretical models explain the development of artificial plasma as an ionizing wavefront moving downward due to ionization by electrons accelerated by HF-excited strong Langmuir turbulence (SLT) generated near the plasma resonance, where the pump frequency matches the plasma frequency. However, the observations suggest also the significance of interactions with upper hybrid and electron Bernstein waves near multiples of the electron gyrofrequency. We describe recent observations and discuss suitable acceleration mechanisms.

Analysis of Wind Tunnel Longitudinal Static and Oscillatory Data of the F-16XL Aircraft

NASA Technical Reports Server (NTRS)

Klein, Vladislav; Murphy, Patrick C.; Curry, Timothy J.; Brandon, Jay M.

1997-01-01

Static and oscillatory wind tunnel data are presented for a 10-percent-scale model of an F-16XL aircraft. Static data include the effect of angle of attack, sideslip angle, and control surface deflections on aerodynamic coefficients. Dynamic data from small-amplitude oscillatory tests are presented at nominal values of angle of attack between 20 and 60 degrees. Model oscillations were performed at five frequencies from 0.6 to 2.9 Hz and one amplitude of 5 degrees. A simple harmonic analysis of the oscillatory data provided Fourier coefficients associated with the in-phase and out-of-phase components of the aerodynamic coefficients. A strong dependence of the oscillatory data on frequency led to the development of models with unsteady terms in the form of indicial functions. Two models expressing the variation of the in-phase and out-of-phase components with angle of attack and frequency were proposed and their parameters estimated from measured data.

An All-Digital Fast Tracking Switching Converter with a Programmable Order Loop Controller for Envelope Tracking RF Power Amplifiers

PubMed Central

Anabtawi, Nijad; Ferzli, Rony; Harmanani, Haidar M.

2017-01-01

This paper presents a step down, switched mode power converter for use in multi-standard envelope tracking radio frequency power amplifiers (RFPA). The converter is based on a programmable order sigma delta modulator that can be configured to operate with either 1st, 2nd, 3rd or 4th order loop filters, eliminating the need for a bulky passive output filter. Output ripple, sideband noise and spectral emission requirements of different wireless standards can be met by configuring the modulator’s filter order and converter’s sampling frequency. The proposed converter is entirely digital and is implemented in 14nm bulk CMOS process for post layout verification. For an input voltage of 3.3V, the converter’s output can be regulated to any voltage level from 0.5V to 2.5V, at a nominal switching frequency of 150MHz. It achieves a maximum efficiency of 94% at 1.5 W output power. PMID:28919657

Perceived Annoyance to Noise Produced by a Distributed Electric Propulsion High Lift System

NASA Technical Reports Server (NTRS)

Palumbo, Dan; Rathsam, Jonathan; Christian, Andrew; Rafaelof, Menachem

2016-01-01

Results of a psychoacoustic test performed to understand the relative annoyance to noise produced by several configurations of a distributed electric propulsion high lift system are given. It is found that the number of propellers in the system is a major factor in annoyance perception. This is an intuitive result as annoyance increases, in general, with frequency, and, the blade passage frequency of the propellers increases with the number of propellers. Additionally, the data indicate that having some variation in the blade passage frequency from propeller-to-propeller is beneficial as it reduces the high tonality generated when all the propellers are spinning in synchrony at the same speed. The propellers can be set to spin at different speeds, but it was found that allowing the motor controllers to drift within 1% of nominal settings produced the best results (lowest overall annoyance). The methodology employed has been demonstrated to be effective in providing timely feedback to designers in the early stages of design development.

Parametric Study of Biconic Re-Entry Vehicles

NASA Technical Reports Server (NTRS)

Steele, Bryan; Banks, Daniel W.; Whitmore, Stephen A.

2007-01-01

An optimization based on hypersonic aerodynamic performance and volumetric efficiency was accomplished for a range of biconic configurations. Both axisymmetric and quasi-axisymmetric geometries (bent and flattened) were analyzed. The aerodynamic optimization wag based on hypersonic simple Incidence angle analysis tools. The range of configurations included those suitable for r lunar return trajectory with a lifting aerocapture at Earth and an overall volume that could support a nominal crew. The results yielded five configurations that had acceptable aerodynamic performance and met overall geometry and size limitations

U.S. Army’s Ground Vehicle Energy Storage

DTIC Science & Technology

2013-04-16

3.7 Voltage range (V) (NCA, NCM) 2.5-4.1 7.5-12.3 10-16.4 15-24.6 17.5-28.7 20-32.8 Nominal Voltage(V) ( LiFePO4 ) 3.3 9.9 13.2 19.8 23.1 26.4 n...x 3.3 Voltage range (V) ( LiFePO4 ) 2.0-3.7 6-11.1 8-14.8 12-22.2 14-25.9 16-29.6 Battery voltage UNCLASSIFIED Ground Systems Power and Energy

Imputation of variants from the 1000 Genomes Project modestly improves known associations and can identify low-frequency variant-phenotype associations undetected by HapMap based imputation.

PubMed

Wood, Andrew R; Perry, John R B; Tanaka, Toshiko; Hernandez, Dena G; Zheng, Hou-Feng; Melzer, David; Gibbs, J Raphael; Nalls, Michael A; Weedon, Michael N; Spector, Tim D; Richards, J Brent; Bandinelli, Stefania; Ferrucci, Luigi; Singleton, Andrew B; Frayling, Timothy M

2013-01-01

Genome-wide association (GWA) studies have been limited by the reliance on common variants present on microarrays or imputable from the HapMap Project data. More recently, the completion of the 1000 Genomes Project has provided variant and haplotype information for several million variants derived from sequencing over 1,000 individuals. To help understand the extent to which more variants (including low frequency (1% ≤ MAF <5%) and rare variants (<1%)) can enhance previously identified associations and identify novel loci, we selected 93 quantitative circulating factors where data was available from the InCHIANTI population study. These phenotypes included cytokines, binding proteins, hormones, vitamins and ions. We selected these phenotypes because many have known strong genetic associations and are potentially important to help understand disease processes. We performed a genome-wide scan for these 93 phenotypes in InCHIANTI. We identified 21 signals and 33 signals that reached P<5×10(-8) based on HapMap and 1000 Genomes imputation, respectively, and 9 and 11 that reached a stricter, likely conservative, threshold of P<5×10(-11) respectively. Imputation of 1000 Genomes genotype data modestly improved the strength of known associations. Of 20 associations detected at P<5×10(-8) in both analyses (17 of which represent well replicated signals in the NHGRI catalogue), six were captured by the same index SNP, five were nominally more strongly associated in 1000 Genomes imputed data and one was nominally more strongly associated in HapMap imputed data. We also detected an association between a low frequency variant and phenotype that was previously missed by HapMap based imputation approaches. An association between rs112635299 and alpha-1 globulin near the SERPINA gene represented the known association between rs28929474 (MAF = 0.007) and alpha1-antitrypsin that predisposes to emphysema (P = 2.5×10(-12)). Our data provide important proof of principle that 1000 Genomes imputation will detect novel, low frequency-large effect associations.

Imputation of Variants from the 1000 Genomes Project Modestly Improves Known Associations and Can Identify Low-frequency Variant - Phenotype Associations Undetected by HapMap Based Imputation

PubMed Central

Wood, Andrew R.; Perry, John R. B.; Tanaka, Toshiko; Hernandez, Dena G.; Zheng, Hou-Feng; Melzer, David; Gibbs, J. Raphael; Nalls, Michael A.; Weedon, Michael N.; Spector, Tim D.; Richards, J. Brent; Bandinelli, Stefania; Ferrucci, Luigi; Singleton, Andrew B.; Frayling, Timothy M.

2013-01-01

Genome-wide association (GWA) studies have been limited by the reliance on common variants present on microarrays or imputable from the HapMap Project data. More recently, the completion of the 1000 Genomes Project has provided variant and haplotype information for several million variants derived from sequencing over 1,000 individuals. To help understand the extent to which more variants (including low frequency (1% ≤ MAF <5%) and rare variants (<1%)) can enhance previously identified associations and identify novel loci, we selected 93 quantitative circulating factors where data was available from the InCHIANTI population study. These phenotypes included cytokines, binding proteins, hormones, vitamins and ions. We selected these phenotypes because many have known strong genetic associations and are potentially important to help understand disease processes. We performed a genome-wide scan for these 93 phenotypes in InCHIANTI. We identified 21 signals and 33 signals that reached P<5×10−8 based on HapMap and 1000 Genomes imputation, respectively, and 9 and 11 that reached a stricter, likely conservative, threshold of P<5×10−11 respectively. Imputation of 1000 Genomes genotype data modestly improved the strength of known associations. Of 20 associations detected at P<5×10−8 in both analyses (17 of which represent well replicated signals in the NHGRI catalogue), six were captured by the same index SNP, five were nominally more strongly associated in 1000 Genomes imputed data and one was nominally more strongly associated in HapMap imputed data. We also detected an association between a low frequency variant and phenotype that was previously missed by HapMap based imputation approaches. An association between rs112635299 and alpha-1 globulin near the SERPINA gene represented the known association between rs28929474 (MAF = 0.007) and alpha1-antitrypsin that predisposes to emphysema (P = 2.5×10−12). Our data provide important proof of principle that 1000 Genomes imputation will detect novel, low frequency-large effect associations. PMID:23696881

Multi-technique characterization of gold electroplating on silver substrates for cultural heritage applications

NASA Astrophysics Data System (ADS)

Ortega-Feliu, I.; Ager, F. J.; Roldán, C.; Ferretti, M.; Juanes, D.; Scrivano, S.; Respaldiza, M. A.; Ferrazza, L.; Traver, I.; Grilli, M. L.

2017-09-01

This work presents a detailed study of a series of silver plates gilded via electroplating techniques in which the characteristics of the coating gold layers are investigated as a function of the electroplating variables (voltage, time, anode surface and temperature). Some reference samples were coated by radio frequency sputtering in order to compare gold layer homogeneity and effective density. Surface analysis was performed by means of atomic and nuclear techniques (SEM-EDX, EDXRF, PIXE and RBS) to obtain information about thickness, homogeneity, effective density, profile concentration of the gold layers and Au-Ag diffusion profiles. The gold layer thickness obtained by PIXE and EDXRF is consistent with the thickness obtained by means of RBS depth profiling. Electroplated gold mass thickness increases with electroplating time, anode area and voltage. However, electrodeposited samples present rough interfaces and gold layer effective densities lower than the nominal density of Au (19.3 g/cm3), whereas sputtering produces uniform layers with nominal density. These analyses provide valuable information to historians and curators and can help the restoration process of gold-plated silver objects.

Interband optical pulse injection locking of quantum dot mode-locked semiconductor laser.

PubMed

Kim, Jimyung; Delfyett, Peter J

2008-07-21

We experimentally demonstrate optical clock recovery from quantum dot mode-locked semiconductor lasers by interband optical pulse injection locking. The passively mode-locked slave laser oscillating on the ground state or the first excited state transition is locked through the injection of optical pulses generated via the opposite transition bands, i.e. the first excited state or the ground state transition from the hybridly mode-locked master laser, respectively. When an optical pulse train generated via the first excited state from the master laser is injected to the slave laser oscillating via ground state, the slave laser shows an asymmetric locking bandwidth around the nominal repetition rate of the slave laser. In the reverse injection case of, i.e. the ground state (master laser) to the first excited state (slave laser), the slave laser does not lock even though both lasers oscillate at the same cavity frequency. In this case, the slave laser only locks to higher injection rates as compared to its own nominal repetition rate, and also shows a large locking bandwidth of 6.7 MHz.

Increasing the intensity of an induction accelerator and reduction of the beam breakup instability

NASA Astrophysics Data System (ADS)

Coleman, J. E.; Moir, D. C.; Ekdahl, C. A.; Johnson, J. B.; McCuistian, B. T.; Sullivan, G. W.; Crawford, M. T.

2014-03-01

A 7 cm cathode has been deployed for use on a 3.8 MV, 80 ns (FWHM) Blumlein, to increase the extracted electron current from the nominal 1.7 to 2.9 kA. The intense relativistic electron bunch is accelerated and transported through a nested solenoid and ferrite induction core lattice consisting of 64 elements, exiting the accelerator with a nominal energy of 19.8 MeV. The principal objective of these experiments is to quantify the space-charge limitations on the beam quality, its coupling with the beam breakup (BBU) instability, and provide an independent validation of the BBU theory in a higher current regime, I >2 kA. Time resolved centroid measurements indicate a reduction in BBU >10× with simply a 50% increase in the average B-field used to transport the beam through the accelerator. A qualitative comparison of experimental and calculated results are presented, which include time resolved current density distributions, radial BBU amplitude relative to the calculated beam envelope, and frequency analyzed BBU amplitude with different accelerator lattice tunes.

Nonlinear optical response of nanocomposites based on KDP single crystal with incorporated Al2O3*nH2O nanofibriles under CW and pulsed laser irradiation at 532 nm

NASA Astrophysics Data System (ADS)

Popov, A. S.; Uklein, A. V.; Multian, V. V.; Dantec, R. Le; Kostenyukova, E. I.; Bezkrovnaya, O. N.; Pritula, I. M.; Gayvoronsky, V. Ya.

2016-11-01

Optical properties and nonlinear optical response due to the CW and pulsed laser radiation self-action at 532 nm were studied in composites based on KDP single crystals with incorporated nanofibriles of nanostructured oxyhydroxide of aluminum (NOA). It was shown a high optical quality and structural homogeneity of nanocomposites KDP:NOA by the transmittance spectra, elastic optical scattering and XRD analysis. It was observed manifestation of the second harmonic generation efficiency enhancement in the KDP:NOA versus the nominally pure KDP (λ=1064 nm, τ=1 ns) that is correlated with efficient refractive index self-modulation Δn ∼10-4 (λ=532 nm, τ=30 ps). In the pyramidal and prismatic growth sectors of the nominally pure KDP crystal it was shown opposite signs of the photoinduced variations both of the refractive index and of the optical absorption/bleaching due to resonant excitation of the native defects at 532 nm. It should be considered for the wide-aperture laser frequency KDP family based convertors fabrication.

Optimal Control Design using an H(sub 2) Method for the Glovebox Integrated Microgravity Isolation Technology (G-Limit)

NASA Technical Reports Server (NTRS)

Calhoun, Philip C.; Hampton, R. David

2002-01-01

The acceleration environment on the International Space Station (ISS) will likely exceed the requirements of many micro-gravity experiments. The Glovebox Integrated Microgravity Isolation Technology (g-LIMIT) is being built by the NASA Marshall Space Flight Center to attenuate the nominal acceleration environment and provide some isolation for microgravity science experiments. G-LIMIT uses Lorentz (voice-coil) magnetic actuators to isolate a platform for mounting science payloads from the nominal acceleration environment. The system utilizes payload acceleration, relative position, and relative orientation measurements in a feedback controller to accomplish the vibration isolation task. The controller provides current commands to six magnetic actuators, producing the required experiment isolation from the ISS acceleration environment. This paper presents the development of a candidate control law to meet the acceleration attenuation requirements for the g-LIMIT experiment platform. The controller design is developed using linear optimal control techniques for frequency-weighted H(sub 2) norms. Comparison of the performance and robustness to plant uncertainty for this control design approach is included in the discussion.

Optimal Control Design Using an H2 Method for the Glovebox Integrated Microgravity Isolation Technology (g-LIMIT)

NASA Technical Reports Server (NTRS)

Calhoun, Phillip C.; Hampton, R. David; Whorton, Mark S.

2001-01-01

The acceleration environment on the International Space Station (ISS) will likely exceed the requirements of many micro-gravity experiments. The Glovebox Integrated Microgravity Isolation Technology (g-LIMIT) is being built by the NASA Marshall Space Flight Center to attenuate the nominal acceleration environment and provide some isolation for micro-gravity science experiments. G-LIMIT uses Lorentz (voice-coil) magnetic actuators to isolate a platform for mounting science payloads from the nominal acceleration environment. The system utilizes payload acceleration, relative position, and relative orientation measurements in a feedback controller to accomplish the vibration isolation task. The controller provides current command to six magnetic actuators, producing the required experiment isolation from the ISS acceleration environment. This paper presents the development of a candidate control law to meet the acceleration attenuation requirements for the g-LIMIT experiment platform. The controller design is developed using linear optimal control techniques for both frequency-weighted H(sub 2) and H(sub infinity) norms. Comparison of the performance and robustness to plant uncertainty for these two optimal control design approaches are included in the discussion.

75 FR 43933 - Request for nominations for members to serve on National Institute of Standards and Technology...

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Effects of model aromatizable (17α-methyltestosterone) and non-aromatizable (5α-dihydrotestosterone) androgens on the adult mummichog (Fundulus heteroclitus) in a short-term reproductive endocrine bioassay.

PubMed

Rutherford, Robert; Lister, Andrea; Hewitt, L Mark; MacLatchy, Deborah

2015-04-01

Androgens originating from pulp mill processing, sewage treatment facilities and agricultural activities have the potential for discharge into aquatic receiving environments. To assess androgen effects on reproductive endocrine status in fish in estuarine environments, male and female adult northern mummichog (Fundulus heteroclitus macrolepidotus) were exposed to an aromatizable androgen (17α-methyltestosterone; MT) and a non-aromatizable androgen (5α-dihydrotestosterone; DHT) in a short-term reproductive endocrine bioassay. Fish were nominally exposed to 10 μg/L or 100 μg/L DHT, or 0.1 μg/L or 1 μg/L MT for 14 days during gonadal recrudescence. Actual concentrations of androgens, as measured by enzyme immunoassay (EIA), were 10-49% of nominal MT 0.1, 3-6% of nominal MT 1, 5-10% of nominal DHT 10 and 3-25% of nominal DHT 100. Female mummichog were impacted to a greater degree by androgen exposure, with increased plasma testosterone (T) at 100 μg/L DHT, depressed plasma 17β-estradiol (E2) at both DHT concentrations and at 1 μg/L MT, as well as depressed in vitro E2 at both MT concentrations and 100 μg/L DHT. Males had depressed plasma T in the 10 μg/L DHT treatment and depressed in vitro 11-ketotestosterone production for both MT concentrations and 10 μg/L DHT. Ovarian aromatase gene expression was induced in females exposed to 1 μg/L MT. DHT at 100 μg/L increased hepatic vitellogenin-1 (VTG1) expression in males and depressed VTG1 expression in females. The range of responses between sexes and among species provides evidence for modes of actions and potential impacts of androgens in aquatic receiving environments. Copyright © 2015 Elsevier Inc. All rights reserved.

Acoustic signal emission monitoring as a novel method to predict steam pops during radiofrequency ablation: preliminary observations.

PubMed

Chik, William W B; Kosobrodov, Roman; Bhaskaran, Abhishek; Barry, Michael Anthony Tony; Nguyen, Doan Trang; Pouliopoulos, Jim; Byth, Karen; Sivagangabalan, Gopal; Thomas, Stuart P; Ross, David L; McEwan, Alistair; Kovoor, Pramesh; Thiagalingam, Aravinda

2015-04-01

Steam pop is an explosive rupture of cardiac tissue caused by tissue overheating above 100 °C, resulting in steam formation, predisposing to serious complications associated with radiofrequency (RF) ablations. However, there are currently no reliable techniques to predict the occurrence of steam pops. We propose the utility of acoustic signals emitted during RF ablation as a novel method to predict steam pop formation and potentially prevent serious complications. Radiofrequency generator parameters (power, impedance, and temperature) were temporally recorded during ablations performed in an in vitro bovine myocardial model. The acoustic system consisted of HTI-96-min hydrophone, microphone preamplifier, and sound card connected to a laptop computer. The hydrophone has the frequency range of 2 Hz to 30 kHz and nominal sensitivity in the range -240 to -165 dB. The sound was sampled at 96 kHz with 24-bit resolution. Output signal from the hydrophone was fed into the camera audio input to synchronize the video stream. An automated system was developed for the detection and analysis of acoustic events. Nine steam pops were observed. Three distinct sounds were identified as warning signals, each indicating rapid steam formation and its release from tissue. These sounds had a broad frequency range up to 6 kHz with several spectral peaks around 2-3 kHz. Subjectively, these warning signals were perceived as separate loud clicks, a quick succession of clicks, or continuous squeaking noise. Characteristic acoustic signals were identified preceding 80% of pops occurrence. Six cardiologists were able to identify 65% of acoustic signals accurately preceding the pop. An automated system identified the characteristic warning signals in 85% of cases. The mean time from the first acoustic signal to pop occurrence was 46 ± 20 seconds. The automated system had 72.7% sensitivity and 88.9% specificity for predicting pops. Easily identifiable characteristic acoustic emissions predictably occur before imminent steam popping during RF ablations. Such acoustic emissions can be carefully monitored during an ablation and may be useful to prevent serious complications during RF delivery. © 2014 Wiley Periodicals, Inc.

76 FR 39379 - Request for Nominations for Members To Serve on National Institute of Standards and Technology...

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2011-07-06

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Stability Assessment and Tuning of an Adaptively Augmented Classical Controller for Launch Vehicle Flight Control

NASA Technical Reports Server (NTRS)

VanZwieten, Tannen; Zhu, J. Jim; Adami, Tony; Berry, Kyle; Grammar, Alex; Orr, Jeb S.; Best, Eric A.

2014-01-01

Recently, a robust and practical adaptive control scheme for launch vehicles [ [1] has been introduced. It augments a classical controller with a real-time loop-gain adaptation, and it is therefore called Adaptive Augmentation Control (AAC). The loop-gain will be increased from the nominal design when the tracking error between the (filtered) output and the (filtered) command trajectory is large; whereas it will be decreased when excitation of flex or sloshing modes are detected. There is a need to determine the range and rate of the loop-gain adaptation in order to retain (exponential) stability, which is critical in vehicle operation, and to develop some theoretically based heuristic tuning methods for the adaptive law gain parameters. The classical launch vehicle flight controller design technics are based on gain-scheduling, whereby the launch vehicle dynamics model is linearized at selected operating points along the nominal tracking command trajectory, and Linear Time-Invariant (LTI) controller design techniques are employed to ensure asymptotic stability of the tracking error dynamics, typically by meeting some prescribed Gain Margin (GM) and Phase Margin (PM) specifications. The controller gains at the design points are then scheduled, tuned and sometimes interpolated to achieve good performance and stability robustness under external disturbances (e.g. winds) and structural perturbations (e.g. vehicle modeling errors). While the GM does give a bound for loop-gain variation without losing stability, it is for constant dispersions of the loop-gain because the GM is based on frequency-domain analysis, which is applicable only for LTI systems. The real-time adaptive loop-gain variation of the AAC effectively renders the closed-loop system a time-varying system, for which it is well-known that the LTI system stability criterion is neither necessary nor sufficient when applying to a Linear Time-Varying (LTV) system in a frozen-time fashion. Therefore, a generalized stability metric for time-varying loop=gain perturbations is needed for the AAC.

Colossal permittivity behavior and its origin in rutile (Mg1/3Ta2/3)xTi1-xO2.

PubMed

Dong, Wen; Chen, Dehong; Hu, Wanbiao; Frankcombe, Terry J; Chen, Hua; Zhou, Chao; Fu, Zhenxiao; Wei, Xiaoyong; Xu, Zhuo; Liu, Zhifu; Li, Yongxiang; Liu, Yun

2017-08-30

This work investigates the synthesis, chemical composition, defect structures and associated dielectric properties of (Mg 2+ , Ta 5+ ) co-doped rutile TiO 2 polycrystalline ceramics with nominal compositions of (Mg 2+ 1/3 Ta 5+ 2/3 ) x Ti 1-x O 2 . Colossal permittivity (>7000) with a low dielectric loss (e.g. 0.002 at 1 kHz) across a broad frequency/temperature range can be achieved at x = 0.5% after careful optimization of process conditions. Both experimental and theoretical evidence indicates such a colossal permittivity and low dielectric loss intrinsically originate from the intragrain polarization that links to the electron-pinned [Formula: see text] defect clusters with a specific configuration, different from the defect cluster form previously reported in tri-/pent-valent ion co-doped rutile TiO 2 . This work extends the research on colossal permittivity and defect formation to bi-/penta-valent ion co-doped rutile TiO 2 and elucidates a likely defect cluster model for this system. We therefore believe these results will benefit further development of colossal permittivity materials and advance the understanding of defect chemistry in solids.

Time dependent heat transfer rates in high Reynolds number hypersonic flowfields

NASA Technical Reports Server (NTRS)

Flanagan, Michael J.

1992-01-01

Time dependent heat transfer rates have been calculated from time dependent temperature measurements in the vicinity of shock-wave boundary-layer interactions due to conical compression ramps on an axisymmetric body. The basic model is a cylindrical body with a 10 degree conical nose. Four conical ramps, 20, 25, 30, and 35 degrees serve as shock wave generators. Flowfield surveys have been made in the vicinity of the conical ramp vertex, the separation point, and the reattachment point. A significant effort was made to characterize the natural frequencies and relative powers of the resulting fluctuations in heat transfer rates. This research effort, sponsored jointly by NASA and the Air Force, was conducted in the Air Force Flight Dynamics Directorate High Reynolds Facility. The nominal freestream Mach number was 6, and the freestream Reynolds numbers ranged from 2.2 million/ft to 30.0 million/ft. Experimental results quantify temperature response and the resulting heat transfer rates as a function of ramp angle and Reynolds number. The temperature response within the flowfield appears to be steady-state for all compression ramp angles and all Reynolds numbers, and hence, the heat transfer rates appear to be steady-state.

Time dependent heat transfer rates in high Reynolds number hypersonic flowfields

NASA Astrophysics Data System (ADS)

Flanagan, Michael J.

1992-09-01

Time dependent heat transfer rates have been calculated from time dependent temperature measurements in the vicinity of shock-wave boundary-layer interactions due to conical compression ramps on an axisymmetric body. The basic model is a cylindrical body with a 10 degree conical nose. Four conical ramps, 20, 25, 30, and 35 degrees serve as shock wave generators. Flowfield surveys have been made in the vicinity of the conical ramp vertex, the separation point, and the reattachment point. A significant effort was made to characterize the natural frequencies and relative powers of the resulting fluctuations in heat transfer rates. This research effort, sponsored jointly by NASA and the Air Force, was conducted in the Air Force Flight Dynamics Directorate High Reynolds Facility. The nominal freestream Mach number was 6, and the freestream Reynolds numbers ranged from 2.2 million/ft to 30.0 million/ft. Experimental results quantify temperature response and the resulting heat transfer rates as a function of ramp angle and Reynolds number. The temperature response within the flowfield appears to be steady-state for all compression ramp angles and all Reynolds numbers, and hence, the heat transfer rates appear to be steady-state.

NASA multipurpose airborne DIAL system and measurements of ozone and aerosol profiles. [DIfferential Absorption Lidar

NASA Technical Reports Server (NTRS)

Browell, E. V.; Carter, A. F.; Shipley, S. T.; Siviter, J. H., Jr.; Hall, W. M.; Allen, R. J.; Butler, C. F.; Mayo, M. N.

1983-01-01

The hardware, operational characteristics, data processing system, and applications of the NASA airborne differential absorption lidar (DIAL) system are described. DIAL functions by assessing the average gas concentration over a specified range interval by analyzing the difference in lidar backscatter signals for laser wavelengths tuned on and off of the molecular absorption line of a gas under investigation. The system comprises two frequency-doubled Nd:YAG lasers pumping two high conversion efficiency tunable dye lasers emitting pulses separated by 100 microsec or less. The return signals are digitized and stored on magnetic tape. The signal collector consists of photomultiplier tubes implanted in a cassegrain telescope. Flight tests of the system involved on-measurements at 285.95 nm and off-measurements at 299.40 nm, which yielded a differential cross section of 1.74 x 10 to the -16th sq cm. In situ measurements with another plane at a nominal altitude of 3.2 km for comparison purposes showed accuracy to within 10% in and above the boundary layer. The system is considered as a test apparatus for more developed versions to be flown on the Shuttle

Satellite gravity gradient grids for geophysics

PubMed Central

Bouman, Johannes; Ebbing, Jörg; Fuchs, Martin; Sebera, Josef; Lieb, Verena; Szwillus, Wolfgang; Haagmans, Roger; Novak, Pavel

2016-01-01

The Gravity field and steady-state Ocean Circulation Explorer (GOCE) satellite aimed at determining the Earth’s mean gravity field. GOCE delivered gravity gradients containing directional information, which are complicated to use because of their error characteristics and because they are given in a rotating instrument frame indirectly related to the Earth. We compute gravity gradients in grids at 225 km and 255 km altitude above the reference ellipsoid corresponding to the GOCE nominal and lower orbit phases respectively, and find that the grids may contain additional high-frequency content compared with GOCE-based global models. We discuss the gradient sensitivity for crustal depth slices using a 3D lithospheric model of the North-East Atlantic region, which shows that the depth sensitivity differs from gradient to gradient. In addition, the relative signal power for the individual gradient component changes comparing the 225 km and 255 km grids, implying that using all components at different heights reduces parameter uncertainties in geophysical modelling. Furthermore, since gravity gradients contain complementary information to gravity, we foresee the use of the grids in a wide range of applications from lithospheric modelling to studies on dynamic topography, and glacial isostatic adjustment, to bedrock geometry determination under ice sheets. PMID:26864314

Unusual Magnetic Response of an S = 1 Antiferromagetic Linear-Chain Material

NASA Astrophysics Data System (ADS)

Xia, Jian-Sheng; Ozarowski, Andrzej; Spurgeon, Peter M.; Graham, Adora G.; Manson, Jamie L.; Meisel, Mark W.

2018-03-01

An S = 1 antiferromagnetic polymeric chain, [Ni(HF2)(3-Clpy)4]BF4 (py = pyridine), also referred to as NBCT, has previously been identified to have intrachain, nearest-neighbor antiferromagnetic interaction strength J/k B = 4.86 K and single-ion anisotropy (zero-field splitting) D/k B = 4.3 K, so the ratio D/J = 0.88 places this system close to the D/J ≈ 1 gapless critical point between the topologically distinct Haldane and Large-D phases. The magnetization was studied over a range of temperatures, 50 mK ≤ T ≤ 1 K, and magnetic fields, B ≤ 10 T, in an attempt to identify a critical field, B c, associated with the closing of a gap, and the present work places an upper bound of B c ≤ (35 ± 10) mT. At higher fields, the observed magnetic response is qualitatively similar to the “excess” signal observed by other workers at 0.5 K and below 3 T. The high-field (up to 14.5 T), multi-frequency (nominally 200 GHz to 425 GHz) ESR spectra at 3 K reveal several features associated with the sample.

Unsteady load on an oscillating Kaplan turbine runner

NASA Astrophysics Data System (ADS)

Puolakka, O.; Keto-Tokoi, J.; Matusiak, J.

2013-02-01

A Kaplan turbine runner oscillating in turbine waterways is subjected to a varying hydrodynamic load. Numerical simulation of the related unsteady flow is time-consuming and research is very limited. In this study, a simplified method based on unsteady airfoil theory is presented for evaluation of the unsteady load for vibration analyses of the turbine shaft line. The runner is assumed to oscillate as a rigid body in spin and axial heave, and the reaction force is resolved into added masses and dampings. The method is applied on three Kaplan runners at nominal operating conditions. Estimates for added masses and dampings are considered to be of a magnitude significant for shaft line vibration. Moderate variation in the added masses and minor variation in the added dampings is found in the frequency range of interest. Reference results for added masses are derived by solving the boundary value problem for small motions of inviscid fluid using the finite element method. Good correspondence is found in the added mass estimates of the two methods. The unsteady airfoil method is considered accurate enough for design purposes. Experimental results are needed for validation of unsteady load analyses.

Detection of the lunar body tide by the Lunar Orbiter Laser Altimeter

PubMed Central

Mazarico, Erwan; Barker, Michael K; Neumann, Gregory A; Zuber, Maria T; Smith, David E

2014-01-01

The Lunar Orbiter Laser Altimeter instrument onboard the Lunar Reconnaissance Orbiter spacecraft collected more than 5 billion measurements in the nominal 50 km orbit over ∼10,000 orbits. The data precision, geodetic accuracy, and spatial distribution enable two-dimensional crossovers to be used to infer relative radial position corrections between tracks to better than ∼1 m. We use nearly 500,000 altimetric crossovers to separate remaining high-frequency spacecraft trajectory errors from the periodic radial surface tidal deformation. The unusual sampling of the lunar body tide from polar lunar orbit limits the size of the typical differential signal expected at ground track intersections to ∼10 cm. Nevertheless, we reliably detect the topographic tidal signal and estimate the associated Love number h2 to be 0.0371 ± 0.0033, which is consistent with but lower than recent results from lunar laser ranging. Key Points Altimetric data are used to create radial constraints on the tidal deformationThe body tide amplitude is estimated from the crossover dataThe estimated Love number is consistent with previous estimates but more precise PMID:26074646

Independent Transitions between Monsoonal and Arid Biomes Revealed by Systematic Revison of a Complex of Australian Geckos (Diplodactylus; Diplodactylidae)

PubMed Central

Oliver, Paul M.; Couper, Patrick J.; Pepper, Mitzy

2014-01-01

How the widespread expansion and intensification of aridity through the Neogene has shaped the Austral biota is a major question in Antipodean biogeography. Lineages distributed across wide aridity gradients provide opportunities to examine the timing, frequency, and direction of transitions between arid and mesic regions. Here, we use molecular genetics and morphological data to investigate the systematics and biogeography of a nominal Australian gecko species (Diplodactylus conspicillatus sensu lato) with a wide distribution spanning most of the Australian Arid Zone (AAZ) and Monsoonal Tropics (AMT). Our data support a minimum of seven genetically distinct and morphologically diagnosable taxa; we thus redefine the type species, ressurrect three names from synonymy, and describe three new species. Our inferred phylogeny suggests the history and diversification of lineages in the AAZ and AMT are intimately linked, with evidence of multiple independent interchanges since the late Miocene. However, despite this shared history, related lineages in these two regions also show evidence of broadly contrasting intra-regional responses to aridification; vicarance and speciation in older and increasingly attenuated mesic regions, versus a more dynamic history including independent colonisations and recent range expansions in the younger AAZ. PMID:25493936

A comprehensive assessment of ionospheric gradients observed in Ecuador during 2013 and 2014 for ground based augmentation systems

NASA Astrophysics Data System (ADS)

Sánchez-Naranjo, S.; Rincón, W.; Ramos-Pollán, R.; González, F. A.; Soley, S.

2017-04-01

Ground Based Augmentation Systems GBAS provide differential corrections to approaching and landing aircrafts in the vicinities of an airport. The ionosphere can introduce an error not accountable by those differential corrections, and a threat model for the Conterminous United States region CONUS was developed in order to consider the highest gradients measured. This study presents the first extensive analysis of ionospheric gradients for Ecuador, from data fully covering 2013 and 2014 collected by their national Global Navigation Satellite System GNSS monitoring network (REGME). In this work it is applied an automated methodology adapted for low latitudes for processing data from dual frequency receivers networks, by considering data from all available days in the date range of the study regardless the geomagnetic indices values. The events found above the CONUS threat model occurred during days of nominal geomagnetic indices, confirming: (1) the higher bounds required for an ionospheric threat model for Ecuador, and (2) that geomagnetic indices are not enough to indicate relevant ionospheric anomalies in low latitude regions, reinforcing the necessity of a continuous monitoring of ionosphere. As additional contribution, the events database is published online, making it available to other researchers.

PFISR GPS tracking mode for researching high-latitude ionospheric electron density gradients associated with GPS scintillation

NASA Astrophysics Data System (ADS)

Loucks, D. C.; Palo, S. E.; Pilinski, M.; Crowley, G.; Azeem, S. I.; Hampton, D. L.

2016-12-01

Ionospheric behavior in the high-latitudes can significantly impact Ultra High Frequency (UHF) signals in the 300 MHz to 3 GHz band, resulting in degradation of Global Positioning System (GPS) position solutions and satellite communications interruptions. To address these operational concerns, a need arises to identify and understand the ionospheric structure that leads to disturbed conditions in the Arctic. Structures in the high-latitude ionosphere are known to change on the order of seconds or less, can be decameters to kilometers in scale, and elongate across magnetic field lines at auroral latitudes. Nominal operations at Poker Flat Incoherent Scatter Radar (PFISR) give temporal resolution on the order of minutes, and range resolution on the order of tens of kilometers, while specialized GPS receivers available for ionospheric sensing have a 100Hz observation sampling rate. One of these, ASTRA's Connected Autonomous Space Environment Sensor (CASES) is used for this study. We have developed a new GPS scintillation tracking mode for PFISR to address open scientific questions regarding temporal and spatial electron density gradients. The mode will be described, a number of experimental campaigns will be analyzed, and results and lessons learned will be presented.

Hazardous behavior of lithium batteries. Case histories

NASA Technical Reports Server (NTRS)

Marincic, N.

1983-01-01

Case histories were described of hazardous behavior for three different cell sizes ranging in nominal capacity from 300 mAh to 12,000 Ah. Design characteristics and other facts believed to have been responsible for the cell explosions, are presented. Obvious facts are discussed as causes for hazardous behavior of lithium batteries in general and oxyhalide batteries in particular.

White Collar Work: Career Ambitions of Fiji Final Year School Students

ERIC Educational Resources Information Center

Nilan, Pam; Cavu, Paula; Tagicakiverata, Isimeli; Hazelman, Emily

2006-01-01

The career ambitions of 1012 pupils in the final years of secondary schooling in Fiji were surveyed. The range of careers they nominated was very narrow, with teaching, nursing and other white collar work in the majority of responses. This stands in somewhat stark contrast to projected labour force needs, and the current serious shortage of…

Learning that Transforms Lives

ERIC Educational Resources Information Center

Taylor, Carol

2012-01-01

In Adult Learners' Week last year there was a first-time national award, sponsored by Pearson, for the Adult Apprentice of the Year. There were 81 nominees from across the age range and from a multitude of jobs. Staff at NIACE were keen to find out more about their stories so they analysed their nominations, asked for more information and…

USGS VDP Infrasound Sensor Evaluation

DOE Office of Scientific and Technical Information (OSTI.GOV)

Slad, George William; Merchant, Bion J.

2016-10-01

Sandia National Laboratories has tested and evaluated two infrasound sensors, the model VDP100 and VDP250, built in-house at the USGS Cascades Volcano Observatory. The purpose of the infrasound sensor evaluation was to determine a measured sensitivity, self-noise, dynamic range and nominal transfer function. Notable features of the VDP sensors include novel and durable construction and compact size.

40 CFR 53.23 - Test procedures.

Code of Federal Regulations, 2010 CFR

2010-07-01

... 40 Protection of Environment 5 2010-07-01 2010-07-01 false Test procedures. 53.23 Section 53.23... Methods SO2, CO, O3, and NO2 § 53.23 Test procedures. (a) Range—(1) Technical definition. Nominal minimum... specified at the lower and upper range limits in concentration units, for example, 0-0.5 p/m. (2) Test...

40 CFR 53.23 - Test procedures.

Code of Federal Regulations, 2011 CFR

2011-07-01

... 40 Protection of Environment 5 2011-07-01 2011-07-01 false Test procedures. 53.23 Section 53.23... Methods SO2, CO, O3, and NO2 § 53.23 Test procedures. (a) Range—(1) Technical definition. Nominal minimum... specified at the lower and upper range limits in concentration units, for example, 0-0.5 p/m. (2) Test...

Temperature Tunable Air-Gap Etalon Filter

NASA Technical Reports Server (NTRS)

Krainak, Michael A.; Stephen, Mark A.; Lunt, David L.

1998-01-01

We report on experimental measurements of a temperature tuned air-gap etalon filter. The filter exhibits temperature dependent wavelength tuning of 54 pm/C. It has a nominal center wavelength of 532 nm. The etalon filter has a 27 pm optical bandpass and 600 pm free spectral range (finesse approximately 22). The experimental results are in close agreement with etalon theory.

Conceptual and linguistic representations of kinds and classes

PubMed Central

Prasada, Sandeep; Hennefield, Laura; Otap, Daniel

2013-01-01

We investigate the hypothesis that our conceptual systems provide two formally distinct ways of representing categories by investigating the manner in which lexical nominals (e.g., tree, picnic table) and phrasal nominals (e.g., black bird, birds that like rice) are interpreted. Four experiments found that lexical nominals may be mapped onto kind representations whereas phrasal nominals map onto class representations but not kind representations. Experiment 1 found that phrasal nominals, unlike lexical nominals, are mapped onto categories whose members need not be of a single kind. Experiments 2 and 3 found that categories named by lexical nominals enter into both class inclusion and kind hierarchies and thus support both class inclusion (is a) and kind specification (kind of) relations, whereas phrasal nominals map onto class representations which support only class inclusion relations. Experiment 4 showed that the two types of nominals represent hierarchical relations in different ways. Phrasal nominals (e.g., white bear) are mapped onto classes that have criteria of membership in addition to those specified by the class picked out by the head noun of the phrase (e.g., bear). In contrast, lexical nominals (e.g., polar bear) specify one way to meet the criteria specified by the more general kind concept (e.g., bear). Implications for the language-conceptual system interface, representation of hierarchical relations, lexicalization, and theories of conceptual combination are discussed. PMID:22671567

7 CFR 917.18 - Nomination of commodity committee members of the Control Committee.

Code of Federal Regulations, 2013 CFR

2013-01-01

... Administrative Bodies § 917.18 Nomination of commodity committee members of the Control Committee. Nominations... committee shall be entitled to nominate shall be based upon the proportion that the previous three fiscal...

7 CFR 917.18 - Nomination of commodity committee members of the Control Committee.

Code of Federal Regulations, 2010 CFR

2010-01-01

... Administrative Bodies § 917.18 Nomination of commodity committee members of the Control Committee. Nominations... committee shall be entitled to nominate shall be based upon the proportion that the previous three fiscal...

7 CFR 917.18 - Nomination of commodity committee members of the Control Committee.

Code of Federal Regulations, 2012 CFR

2012-01-01

... Administrative Bodies § 917.18 Nomination of commodity committee members of the Control Committee. Nominations... committee shall be entitled to nominate shall be based upon the proportion that the previous three fiscal...

7 CFR 917.18 - Nomination of commodity committee members of the Control Committee.

Code of Federal Regulations, 2014 CFR

2014-01-01

... Administrative Bodies § 917.18 Nomination of commodity committee members of the Control Committee. Nominations... committee shall be entitled to nominate shall be based upon the proportion that the previous three fiscal...

7 CFR 917.18 - Nomination of commodity committee members of the Control Committee.

Code of Federal Regulations, 2011 CFR

2011-01-01

... Administrative Bodies § 917.18 Nomination of commodity committee members of the Control Committee. Nominations... committee shall be entitled to nominate shall be based upon the proportion that the previous three fiscal...

On Impedance Spectroscopy of Supercapacitors

NASA Astrophysics Data System (ADS)

Uchaikin, V. V.; Sibatov, R. T.; Ambrozevich, A. S.

2016-10-01

Supercapacitors are often characterized by responses measured by methods of impedance spectroscopy. In the frequency domain these responses have the form of power-law functions or their linear combinations. The inverse Fourier transform leads to relaxation equations with integro-differential operators of fractional order under assumption that the frequency response is independent of the working voltage. To compare long-term relaxation kinetics predicted by these equations with the observed one, charging-discharging of supercapacitors (with nominal capacitances of 0.22, 0.47, and 1.0 F) have been studied by means of registration of the current response to a step voltage signal. It is established that the reaction of devices under study to variations of the charging regime disagrees with the model of a homogeneous linear response. It is demonstrated that relaxation is well described by a fractional stretched exponent.

Development of procedures for calculating stiffness and damping properties of elastomers in engineering applications. Part 2: Elastomer characteristics at constant temperature

NASA Technical Reports Server (NTRS)

Gupta, P. K.; Tessarzik, J. M.; Cziglenyi, L.

1974-01-01

Dynamic properties of a commerical polybutadiene compound were determined at a constant temperature of 32 C by a forced-vibration resonant mass type of apparatus. The constant thermal state of the elastomer was ensured by keeping the ambient temperature constant and by limiting the power dissipation in the specimen. Experiments were performed with both compression and shear specimens at several preloads (nominal strain varying from 0 to 5 percent), and the results are reported in terms of a complex stiffness as a function of frequency. Very weak frequency dependence is observed and a simple power law type of correlation is shown to represent the data well. Variations in the complex stiffness as a function of preload are also found to be small for both compression and shear specimens.

A High-Voltage Integrated Circuit Engine for a Dielectrophoresis-based Programmable Micro-Fluidic Processor

PubMed Central

Current, K. Wayne; Yuk, Kelvin; McConaghy, Charles; Gascoyne, Peter R. C.; Schwartz, Jon A.; Vykoukal, Jody V.; Andrews, Craig

2010-01-01

A high-voltage (HV) integrated circuit has been demonstrated to transport droplets on programmable paths across its coated surface. This chip is the engine for a dielectrophoresis (DEP)-based micro-fluidic lab-on-a-chip system. This chip creates DEP forces that move and help inject droplets. Electrode excitation voltage and frequency are variable. With the electrodes driven with a 100V peak-to-peak periodic waveform, the maximum high-voltage electrode waveform frequency is about 200Hz. Data communication rate is variable up to 250kHz. This demonstration chip has a 32×32 array of nominally 100V electrode drivers. It is fabricated in a 130V SOI CMOS fabrication technology, dissipates a maximum of 1.87W, and is about 10.4 mm × 8.2 mm. PMID:23989241

The brightness temperature of Venus and the absolute flux-density scale at 608 MHz.

NASA Technical Reports Server (NTRS)

Muhleman, D. O.; Berge, G. L.; Orton, G. S.

1973-01-01

The disk temperature of Venus was measured at 608 MHz near the inferior conjunction of 1972, and a value of 498 plus or minus 33 K was obtained using a nominal CKL flux-density scale. The result is consistent with earlier measurements, but has a much smaller uncertainty. Our theoretical model prediction is larger by a factor of 1.21 plus or minus 0.09. This discrepancy has been noticed previously for frequencies below 1400 MHz, but was generally disregarded because of the large observational uncertainties. No way could be found to change the model to produce agreement without causing a conflict with well-established properties of Venus. Thus it is suggested that the flux-density scale may require an upward revision, at least near this frequency, in excess of what has previously been considered likely.

Optical models for radio-frequency-magnetron reactively sputtered AlN films

NASA Astrophysics Data System (ADS)

Easwarakhanthan, T.; Assouar, M. B.; Pigeat, P.; Alnot, P.

2005-10-01

The optical properties of aluminum nitrate (AlN) films reactively sputtered on Si substrates using radio-frequency (rf) magnetron have been studied in this work from multiwavelength spectroscopic ellipsometry (SE) measurements performed over the 290-615 nm wavelength range. The SE modeling carried out with care to adhere as much to the ellipsometric fitting qualities is also backed up with atomic force microscopy and x-ray-diffraction measurements taken on these films thus grown to nominal thicknesses from 40 to 150 nm under the same optimized experimental conditions. It follows that the model describing the optical properties of the thicker AlN films should consist at least in three layers on the Si substrate: an almost roughnessless smooth surface overlayer that is presumed essentially of Al2O3, a bulk AlN layer, and an AlN interface layer that has a refractive index dispersion falling in the range from 2.04 [312 nm] to 1.91 [615 nm] on the average and is fairly distinguishable from the slightly higher bulk layer index which drops correspondingly from 2.12 to 1.99. These index values imply that, beneath the partly or mostly oxidized surface AlN layer, the films comprise a polycrystalline-structured bulk AlN layer above a less-microstructurally-ordered interface layer that extends over 40-55 nm from the substrate among thicker films. This ellipsometric evidence indicating the existence of the interface layer is consistent with those interface layers confirmed through electron microscopy in some previous works. However, the ellipsometrically insufficient thinner AlN films may be only modeled with the surface layer and an AlN layer. The film surface oxide layer thickness varies between 5 and 15 nm among samples. The refractive index dispersions, the layer thicknesses, and the lateral thickness variation of the films are given and discussed regarding the optical constitution of these films and the ellipsometric validity of these parameters.

Characteristics of strongly-forced turbulent jets and non-premixed jet flames

NASA Astrophysics Data System (ADS)

Lakshminarasimhan, K.; Clemens, N. T.; Ezekoye, O. A.

2006-10-01

Previous researchers have demonstrated that strong pulsations of the fuel flow rate can significantly reduce the flame length and luminosity of laminar/transitional non-premixed jet flames. The physical mechanisms responsible for these changes are investigated experimentally in acoustically-forced jet flows where the peak velocity fluctuations are up to eight times the mean flow velocity. Both reacting and non-reacting flows were studied and Reynolds numbers, based on the mean flow properties, ranged from 800 to 10,000 (corresponding to peak Reynolds numbers of 1,450-23,000), and forcing frequencies ranged from 290 to 1,140 Hz. Both the first and second organ-pipe resonance modes of the fuel delivery tube were excited to obtain these frequencies. An analysis of the acoustic forcing characteristics within the resonance tube is provided in order to understand the source of the high amplitude forcing. Flow visualization of jets with first resonant forcing confirms the presence of large-scale coherent vortices and strong reverse flow near the exit of the fuel tube. With second-resonant forcing, however, vortices are not emitted from the tube as they are drawn back into the fuel tube before they can fully form. Increased fine-scale turbulence is associated with both resonant cases, but particularly at second resonance. The power spectra of the velocity fluctuations for a resonantly pulsed jet show the presence of an inertial subrange indicating that the flow becomes fully turbulent even for mean-Reynolds-number jets that are nominally laminar. It is shown that these pulsed jet flows exhibit strong similarities to synthetic jets and that the Strouhal number, based on the maximum velocity at the fuel tube exit, is the dominant parameter for scaling these flows. The Strouhal number determines the downstream location where the coherent vortices breakdown, and is found to provide better collapse of flame length data (both current and previous) than other parameters that have been used in the literature.

A Frequency Domain Approach to Pretest Analysis Model Correlation and Model Updating for the Mid-Frequency Range

DTIC Science & Technology

2009-02-01

range of modal analysis and the high frequency region of statistical energy analysis , is referred to as the mid-frequency range. The corresponding...frequency range of modal analysis and the high frequency region of statistical energy analysis , is referred to as the mid-frequency range. The...predictions. The averaging process is consistent with the averaging done in statistical energy analysis for stochastic systems. The FEM will always

44 CFR 150.3 - Nomination process.

Code of Federal Regulations, 2013 CFR

2013-10-01

... Section 150.3 Emergency Management and Assistance FEDERAL EMERGENCY MANAGEMENT AGENCY, DEPARTMENT OF... Nomination process. (a) The Nominating Officials nominating Firefighters and Civil Defense Officers shall...) Civil defense officer (or member of a recognized civil defense or emergency preparedness organization...

44 CFR 150.3 - Nomination process.

Code of Federal Regulations, 2012 CFR

2012-10-01

... Section 150.3 Emergency Management and Assistance FEDERAL EMERGENCY MANAGEMENT AGENCY, DEPARTMENT OF... Nomination process. (a) The Nominating Officials nominating Firefighters and Civil Defense Officers shall...) Civil defense officer (or member of a recognized civil defense or emergency preparedness organization...

44 CFR 150.3 - Nomination process.

Code of Federal Regulations, 2011 CFR

2011-10-01

... Section 150.3 Emergency Management and Assistance FEDERAL EMERGENCY MANAGEMENT AGENCY, DEPARTMENT OF... Nomination process. (a) The Nominating Officials nominating Firefighters and Civil Defense Officers shall...) Civil defense officer (or member of a recognized civil defense or emergency preparedness organization...

44 CFR 150.3 - Nomination process.

Code of Federal Regulations, 2010 CFR

2010-10-01

... Section 150.3 Emergency Management and Assistance FEDERAL EMERGENCY MANAGEMENT AGENCY, DEPARTMENT OF... Nomination process. (a) The Nominating Officials nominating Firefighters and Civil Defense Officers shall...) Civil defense officer (or member of a recognized civil defense or emergency preparedness organization...

44 CFR 150.3 - Nomination process.

Code of Federal Regulations, 2014 CFR

2014-10-01

... Section 150.3 Emergency Management and Assistance FEDERAL EMERGENCY MANAGEMENT AGENCY, DEPARTMENT OF... Nomination process. (a) The Nominating Officials nominating Firefighters and Civil Defense Officers shall...) Civil defense officer (or member of a recognized civil defense or emergency preparedness organization...

77 FR 19056 - Information Reporting Program Advisory Committee (IRPAC); Nominations

Federal Register 2010, 2011, 2012, 2013, 2014

2012-03-29

... DEPARTMENT OF TREASURY Internal Revenue Service Information Reporting Program Advisory Committee (IRPAC); Nominations AGENCY: Internal Revenue Service, Department of Treasury. ACTION: Request for Nominations. SUMMARY: The Internal Revenue Service (IRS) requests nominations of individuals for selection to...

78 FR 19582 - Information Reporting Program Advisory Committee (IRPAC); Nominations

Federal Register 2010, 2011, 2012, 2013, 2014

2013-04-01

... DEPARTMENT OF TREASURY Internal Revenue Service Information Reporting Program Advisory Committee (IRPAC); Nominations AGENCY: Internal Revenue Service, Department of Treasury. ACTION: Request for Nominations. SUMMARY: The Internal Revenue Service (IRS) requests nominations of individuals for selection to...

Racially diverse classrooms: effects of classroom racial composition on interracial peer relationships.

PubMed

Barth, Joan M; McDonald, Kristina L; Lochman, John E; Boxmeyer, Carolyn; Powell, Nicole; Dillon, Casey; Sallee, Meghann

2013-01-01

The purpose of this study was to examine the interactive effects that a child's race and the racial composition of a classroom have on a variety of sociometric measures. Sociometric nominations were collected from 872 fifth-grade students (48% male, 48% Black) who were in classrooms that ranged from nearly all Black to nearly all White students. Hierarchical Linear Modeling analyses indicated that the race of the child, the race of the rater, and the classroom race composition each impacted sociometric nominations. Results suggest that schools that are more balanced in the distribution of Black and White students might promote more positive interracial peer relationships. However, opportunities to be highly liked and to be perceived as a leader might be greatest in a school in which the child is in the clear racial majority. © 2013 American Orthopsychiatric Association.

Association of prostate cancer risk variants with clinicopathologic characteristics of the disease

PubMed Central

Xu, Jianfeng; Isaacs, Sarah D.; Sun, Jielin; Li, Ge; Wiley, Kathleen E.; Zhu, Yi; Hsu, Fang-Chi; Wiklund, Fredrik; Turner, Aubrey R.; Adams, Tamara S.; Liu, Wennuan; Trock, Bruce J.; Partin, Alan W.; Chang, Baoli; Walsh, Patrick C.; Grönberg, Henrik; Isaacs, William; Zheng, Siqun

2009-01-01

Purpose Fifteen independent genetic variants have been implicated in prostate cancer risk by recent genome-wide association studies. However, their association with clinicopathologic features of prostate cancer is uncertain. Experimental Design We systematically evaluated these 15 variants in 1,563 prostate cancer patients undergoing radical prostatectomy, taking advantage of the uniform tumor stage and grade information available for each of these cases. Associations of these variants with aggressiveness, pathologic Gleason scores, pathologic stage, age at diagnosis, or serum PSA levels were tested. Results After adjusting for multiple testing, none of the SNPs was individually or cumulatively associated with aggressiveness or individual clinicopathologic variables of prostate cancer such as Gleason scores, pathologic stage, or age at diagnosis of prostate cancer. The reported risk allele (G) for SNP rs2735839 in the KLK3 gene at 19q13 was more frequent in less aggressive prostate cancer patients (0.89) than in more aggressive prostate cancer patients (0.86), nominal P = 0.03, or in controls (0.86), nominal P = 0.04. Considering that this allele was also significantly associated with higher serum PSA levels among controls (nominal P = 0.003), the observed trend of higher frequency of this risk allele between less and more aggressive prostate cancer, or between less aggressive and controls may be due to detection bias of PSA screening. Conclusions Prostate cancer risk variants recently discovered from genome-wide case-control association studies are not associated with clinicopathologic variables in this population. Case-case studies are urgently needed in order to discover genetic variants that predict tumor aggressiveness. PMID:18794092

Statistical Significance and Baseline Monitoring.

DTIC Science & Technology

1984-07-01

impacted at once........................... 24 6 Observed versus nominal a levels for multivariate tests of data sets (50 runs of 4 groups each...cumulative proportion of the observations found for each nominal level. The results of the comparisons of the observed versus nominal a levels for the...a values are always higher than nominal levels. Virtual- . .,ly all nominal a levels are below 0.20. In other words, the discriminant analysis models

Hysteresis and uncertainty in soil water-retention curve parameters

USGS Publications Warehouse

Likos, William J.; Lu, Ning; Godt, Jonathan W.

2014-01-01

Accurate estimates of soil hydraulic parameters representing wetting and drying paths are required for predicting hydraulic and mechanical responses in a large number of applications. A comprehensive suite of laboratory experiments was conducted to measure hysteretic soil-water characteristic curves (SWCCs) representing a wide range of soil types. Results were used to quantitatively assess differences and uncertainty in three simplifications frequently adopted to estimate wetting-path SWCC parameters from more easily measured drying curves. They are the following: (1) αw=2αd, (2) nw=nd, and (3) θws=θds, where α, n, and θs are fitting parameters entering van Genuchten’s commonly adopted SWCC model, and the superscripts w and d indicate wetting and drying paths, respectively. The average ratio αw/αd for the data set was 2.24±1.25. Nominally cohesive soils had a lower αw/αd ratio (1.73±0.94) than nominally cohesionless soils (3.14±1.27). The average nw/nd ratio was 1.01±0.11 with no significant dependency on soil type, thus confirming the nw=nd simplification for a wider range of soil types than previously available. Water content at zero suction during wetting (θws) was consistently less than during drying (θds) owing to air entrapment. The θws/θds ratio averaged 0.85±0.10 and was comparable for nominally cohesive (0.87±0.11) and cohesionless (0.81±0.08) soils. Regression statistics are provided to quantitatively account for uncertainty in estimating hysteretic retention curves. Practical consequences are demonstrated for two case studies.

Building Consensus: Development of Best Practice Guidelines on Wrong Level Surgery in Spinal Deformity.

PubMed

Vitale, Michael; Minkara, Anas; Matsumoto, Hiroko; Albert, Todd; Anderson, Richard; Angevine, Peter; Buckland, Aaron; Cho, Samuel; Cunningham, Matthew; Errico, Thomas; Fischer, Charla; Kim, Han Jo; Lehman, Ronald; Lonner, Baron; Passias, Peter; Protopsaltis, Themistocles; Schwab, Frank; Lenke, Lawrence

Consensus-building using the Delphi and nominal group technique. To establish best practice guidelines using formal techniques of consensus building among a group of experienced spinal deformity surgeons to avert wrong-level spinal deformity surgery. Numerous previous studies have demonstrated that wrong-level spinal deformity occurs at a substantial rate, with more than half of all spine surgeons reporting direct or indirect experience operating on the wrong levels. Nevertheless, currently, guidelines to avert wrong-level spinal deformity surgery have not been developed. The Delphi process and nominal group technique were used to formally derive consensus among 16 fellowship-trained spine surgeons. Surgeons were surveyed for current practices, presented with the results of a systematic review, and asked to vote anonymously for or against item inclusion during three iterative rounds. Agreement of 80% or higher was considered consensus. Items near consensus (70% to 80% agreement) were probed in detail using the nominal group technique in a facilitated group meeting. Participants had a mean of 13.4 years of practice (range: 2-32 years) and 103.1 (range: 50-250) annual spinal deformity surgeries, with a combined total of 24,200 procedures. Consensus was reached for the creation of best practice guidelines (BPGs) consisting of 17 interventions to avert wrong-level surgery. A final checklist consisting of preoperative and intraoperative methods, including standardized vertebral-level counting and optimal imaging criteria, was supported by 100% of participants. We developed consensus-based best practice guidelines for the prevention of wrong-vertebral-level surgery. This can serve as a tool to reduce the variability in preoperative and intraoperative practices and guide research regarding the effectiveness of such interventions on the incidence of wrong-level surgery. Level V. Copyright © 2017 Scoliosis Research Society. Published by Elsevier Inc. All rights reserved.

47 CFR 18.309 - Frequency range of measurements.

Code of Federal Regulations, 2010 CFR

2010-10-01

... MEDICAL EQUIPMENT Technical Standards § 18.309 Frequency range of measurements. (a) For field strength measurements: Frequency band in which device operates (MHz) Range of frequency measurements Lowest frequency...

76 FR 52016 - NASA Federal Advisory Committees; Nominations and Self-Nominations

Federal Register 2010, 2011, 2012, 2013, 2014

2011-08-19

... NATIONAL AERONAUTICS AND SPACE ADMINISTRATION [Notice: (11- 075)] NASA Federal Advisory Committees; Nominations and Self- Nominations AGENCY: National Aeronautics and Space Administration. ACTION: Public... the Federal Advisory Committee Act, Public Law 92-463, as amended, the National Aeronautics and Space...

7 CFR 987.124 - Nomination and polling.

Code of Federal Regulations, 2010 CFR

2010-01-01

... 7 Agriculture 8 2010-01-01 2010-01-01 false Nomination and polling. 987.124 Section 987.124 Agriculture Regulations of the Department of Agriculture (Continued) AGRICULTURAL MARKETING SERVICE (Marketing... IN RIVERSIDE COUNTY, CALIFORNIA Administrative Rules Nominations § 987.124 Nomination and polling. (a...

7 CFR 1150.133 - Nominations.

Code of Federal Regulations, 2012 CFR

2012-01-01

... 7 Agriculture 9 2012-01-01 2012-01-01 false Nominations. 1150.133 Section 1150.133 Agriculture Regulations of the Department of Agriculture (Continued) AGRICULTURAL MARKETING SERVICE (Marketing Agreements... Order National Dairy Promotion and Research Board § 1150.133 Nominations. Nominations for members of the...

7 CFR 1150.133 - Nominations.

Code of Federal Regulations, 2013 CFR

2013-01-01

... 7 Agriculture 9 2013-01-01 2013-01-01 false Nominations. 1150.133 Section 1150.133 Agriculture Regulations of the Department of Agriculture (Continued) AGRICULTURAL MARKETING SERVICE (MARKETING AGREEMENTS... Order National Dairy Promotion and Research Board § 1150.133 Nominations. Nominations for members of the...

NekNominate: Social Norms, Social Media, and Binge Drinking.

PubMed

Wombacher, Kevin; Reno, Jenna E; Veil, Shari R

2017-05-01

This study examines the social-media-based binge drinking game NekNominate and how this phenomenon is related to social norms. NekNominate is a game wherein players are nominated to film themselves "neking" or chugging copious amounts of alcohol or drinking alcohol in a novel or humorous manner. The player then nominates other players via social media who then have a specific timeframe in which they must complete their challenge or face ridicule. Health communication research on drinking behaviors has often looked at the role of social norms in determining these behaviors. News stories (n = 44) of NekNominate and tweets (n = 851) culled using the hashtag #NekNominate during three different time periods are analyzed to identify the normative forces at play in this recent phenomenon.

Communications Blackout Predictions for Atmospheric Entry of Mars Science Laboratory

NASA Technical Reports Server (NTRS)

Morabito, David D.; Edquist, Karl T.

2005-01-01

The Mars Science Laboratory (MSL) is expected to be a long-range, long-duration science laboratory rover on the Martian surface. MSL will provide a significant milestone that paves the way for future landed missions to Mars. NASA is studying options to launch MSL as early as 2009. There are three elements to the spacecraft; carrier (cruise stage), entry vehicle, and rover. The rover will have a UHF proximity link as the primary path for EDL communications and may have an X-band direct-to-Earth link as a back-up. Given the importance of collecting critical event telemetry data during atmospheric entry, it is important to understand the ability of a signal link to be maintained, especially during the period near peak convective heating. The received telemetry during entry (or played back later) will allow for the performance of the Entry-Descent-Landing technologies to be assessed. These technologies include guided entry for precision landing, a new sky-crane landing system and powered descent. MSL will undergo an entry profile that may result in a potential communications blackout caused by ionized particles for short periods near peak heating. The vehicle will use UHF and possibly X-band during the entry phase. The purpose of this rep0rt is to quantify or bound the likelihood of any such blackout at UHF frequencies (401 MHz) and X-band frequencies (8.4 GHz). Two entry trajectory scenarios were evaluated: a stressful entry trajectory to quantify an upper-bound for any possible blackout period, and a nominal trajectory to quantify likelihood of blackout for such cases.

45 CFR 1801.18 - Limitations on nominations.

Code of Federal Regulations, 2014 CFR

2014-10-01

... 45 Public Welfare 4 2014-10-01 2014-10-01 false Limitations on nominations. 1801.18 Section 1801.18 Public Welfare Regulations Relating to Public Welfare (Continued) HARRY S. TRUMAN SCHOLARSHIP FOUNDATION HARRY S. TRUMAN SCHOLARSHIP PROGRAM Nominations § 1801.18 Limitations on nominations. A candidate...

45 CFR 1801.18 - Limitations on nominations.

Code of Federal Regulations, 2011 CFR

2011-10-01

... 45 Public Welfare 4 2011-10-01 2011-10-01 false Limitations on nominations. 1801.18 Section 1801.18 Public Welfare Regulations Relating to Public Welfare (Continued) HARRY S. TRUMAN SCHOLARSHIP FOUNDATION HARRY S. TRUMAN SCHOLARSHIP PROGRAM Nominations § 1801.18 Limitations on nominations. A candidate...

45 CFR 1801.18 - Limitations on nominations.

Code of Federal Regulations, 2010 CFR

2010-10-01

... 45 Public Welfare 4 2010-10-01 2010-10-01 false Limitations on nominations. 1801.18 Section 1801.18 Public Welfare Regulations Relating to Public Welfare (Continued) HARRY S. TRUMAN SCHOLARSHIP FOUNDATION HARRY S. TRUMAN SCHOLARSHIP PROGRAM Nominations § 1801.18 Limitations on nominations. A candidate...

45 CFR 1801.18 - Limitations on nominations.

Code of Federal Regulations, 2012 CFR

2012-10-01

... 45 Public Welfare 4 2012-10-01 2012-10-01 false Limitations on nominations. 1801.18 Section 1801.18 Public Welfare Regulations Relating to Public Welfare (Continued) HARRY S. TRUMAN SCHOLARSHIP FOUNDATION HARRY S. TRUMAN SCHOLARSHIP PROGRAM Nominations § 1801.18 Limitations on nominations. A candidate...

45 CFR 1801.18 - Limitations on nominations.

Code of Federal Regulations, 2013 CFR

2013-10-01

... 45 Public Welfare 4 2013-10-01 2013-10-01 false Limitations on nominations. 1801.18 Section 1801.18 Public Welfare Regulations Relating to Public Welfare (Continued) HARRY S. TRUMAN SCHOLARSHIP FOUNDATION HARRY S. TRUMAN SCHOLARSHIP PROGRAM Nominations § 1801.18 Limitations on nominations. A candidate...

7 CFR 1220.203 - Nominations.

Code of Federal Regulations, 2010 CFR

2010-01-01

... CONSUMER INFORMATION Soybean Promotion and Research Order United Soybean Board § 1220.203 Nominations. All... be filled. (e) Nominations may be submitted in order of preference and for the initial Board, in order of preference for staggered terms. Should the Secretary reject any nomination submitted and there...

7 CFR 932.31 - Failure to nominate.

Code of Federal Regulations, 2012 CFR

2012-01-01

... 7 Agriculture 8 2012-01-01 2012-01-01 false Failure to nominate. 932.31 Section 932.31 Agriculture Regulations of the Department of Agriculture (Continued) AGRICULTURAL MARKETING SERVICE (Marketing Agreements... Regulating Handling Olive Administrative Committee § 932.31 Failure to nominate. If nominations for any...

7 CFR 953.20 - Failure to nominate.

Code of Federal Regulations, 2014 CFR

2014-01-01

... 7 Agriculture 8 2014-01-01 2014-01-01 false Failure to nominate. 953.20 Section 953.20 Agriculture Regulations of the Department of Agriculture (Continued) AGRICULTURAL MARKETING SERVICE (MARKETING AGREEMENTS... STATES Order Regulating Handling Administrative Committee § 953.20 Failure to nominate. If nominations...

7 CFR 953.20 - Failure to nominate.

Code of Federal Regulations, 2012 CFR

2012-01-01

... 7 Agriculture 8 2012-01-01 2012-01-01 false Failure to nominate. 953.20 Section 953.20 Agriculture Regulations of the Department of Agriculture (Continued) AGRICULTURAL MARKETING SERVICE (Marketing Agreements... STATES Order Regulating Handling Administrative Committee § 953.20 Failure to nominate. If nominations...

7 CFR 932.31 - Failure to nominate.

Code of Federal Regulations, 2014 CFR

2014-01-01

... 7 Agriculture 8 2014-01-01 2014-01-01 false Failure to nominate. 932.31 Section 932.31 Agriculture Regulations of the Department of Agriculture (Continued) AGRICULTURAL MARKETING SERVICE (MARKETING AGREEMENTS... Regulating Handling Olive Administrative Committee § 932.31 Failure to nominate. If nominations for any...

7 CFR 927.25 - Failure to nominate.

Code of Federal Regulations, 2011 CFR

2011-01-01

... 7 Agriculture 8 2011-01-01 2011-01-01 false Failure to nominate. 927.25 Section 927.25 Agriculture Regulations of the Department of Agriculture (Continued) AGRICULTURAL MARKETING SERVICE (Marketing Agreements... Order Regulating Handling Administrative Bodies § 927.25 Failure to nominate. In the event nominations...

7 CFR 932.31 - Failure to nominate.

Code of Federal Regulations, 2011 CFR

2011-01-01

... 7 Agriculture 8 2011-01-01 2011-01-01 false Failure to nominate. 932.31 Section 932.31 Agriculture Regulations of the Department of Agriculture (Continued) AGRICULTURAL MARKETING SERVICE (Marketing Agreements... Regulating Handling Olive Administrative Committee § 932.31 Failure to nominate. If nominations for any...

7 CFR 953.20 - Failure to nominate.

Code of Federal Regulations, 2010 CFR

2010-01-01

... 7 Agriculture 8 2010-01-01 2010-01-01 false Failure to nominate. 953.20 Section 953.20 Agriculture Regulations of the Department of Agriculture (Continued) AGRICULTURAL MARKETING SERVICE (Marketing Agreements... STATES Order Regulating Handling Administrative Committee § 953.20 Failure to nominate. If nominations...

7 CFR 917.26 - Failure to nominate.

Code of Federal Regulations, 2011 CFR

2011-01-01

... 7 Agriculture 8 2011-01-01 2011-01-01 false Failure to nominate. 917.26 Section 917.26 Agriculture Regulations of the Department of Agriculture (Continued) AGRICULTURAL MARKETING SERVICE (Marketing Agreements... CALIFORNIA Order Regulating Handling Administrative Bodies § 917.26 Failure to nominate. If nominations are...

7 CFR 927.25 - Failure to nominate.

Code of Federal Regulations, 2012 CFR

2012-01-01

... 7 Agriculture 8 2012-01-01 2012-01-01 false Failure to nominate. 927.25 Section 927.25 Agriculture Regulations of the Department of Agriculture (Continued) AGRICULTURAL MARKETING SERVICE (Marketing Agreements... Order Regulating Handling Administrative Bodies § 927.25 Failure to nominate. In the event nominations...

7 CFR 917.26 - Failure to nominate.

Code of Federal Regulations, 2014 CFR

2014-01-01

... 7 Agriculture 8 2014-01-01 2014-01-01 false Failure to nominate. 917.26 Section 917.26 Agriculture Regulations of the Department of Agriculture (Continued) AGRICULTURAL MARKETING SERVICE (MARKETING AGREEMENTS... CALIFORNIA Order Regulating Handling Administrative Bodies § 917.26 Failure to nominate. If nominations are...

7 CFR 927.25 - Failure to nominate.

Code of Federal Regulations, 2010 CFR

2010-01-01

... 7 Agriculture 8 2010-01-01 2010-01-01 false Failure to nominate. 927.25 Section 927.25 Agriculture Regulations of the Department of Agriculture (Continued) AGRICULTURAL MARKETING SERVICE (Marketing Agreements... Order Regulating Handling Administrative Bodies § 927.25 Failure to nominate. In the event nominations...

7 CFR 917.26 - Failure to nominate.

Code of Federal Regulations, 2013 CFR

2013-01-01

... 7 Agriculture 8 2013-01-01 2013-01-01 false Failure to nominate. 917.26 Section 917.26 Agriculture Regulations of the Department of Agriculture (Continued) AGRICULTURAL MARKETING SERVICE (MARKETING AGREEMENTS... CALIFORNIA Order Regulating Handling Administrative Bodies § 917.26 Failure to nominate. If nominations are...

7 CFR 917.26 - Failure to nominate.

Code of Federal Regulations, 2012 CFR

2012-01-01

... 7 Agriculture 8 2012-01-01 2012-01-01 false Failure to nominate. 917.26 Section 917.26 Agriculture Regulations of the Department of Agriculture (Continued) AGRICULTURAL MARKETING SERVICE (Marketing Agreements... CALIFORNIA Order Regulating Handling Administrative Bodies § 917.26 Failure to nominate. If nominations are...

7 CFR 932.31 - Failure to nominate.

Code of Federal Regulations, 2010 CFR

2010-01-01

... 7 Agriculture 8 2010-01-01 2010-01-01 false Failure to nominate. 932.31 Section 932.31 Agriculture Regulations of the Department of Agriculture (Continued) AGRICULTURAL MARKETING SERVICE (Marketing Agreements... Regulating Handling Olive Administrative Committee § 932.31 Failure to nominate. If nominations for any...

7 CFR 917.26 - Failure to nominate.

Code of Federal Regulations, 2010 CFR

2010-01-01

... 7 Agriculture 8 2010-01-01 2010-01-01 false Failure to nominate. 917.26 Section 917.26 Agriculture Regulations of the Department of Agriculture (Continued) AGRICULTURAL MARKETING SERVICE (Marketing Agreements... CALIFORNIA Order Regulating Handling Administrative Bodies § 917.26 Failure to nominate. If nominations are...

7 CFR 932.31 - Failure to nominate.

Code of Federal Regulations, 2013 CFR

2013-01-01

... 7 Agriculture 8 2013-01-01 2013-01-01 false Failure to nominate. 932.31 Section 932.31 Agriculture Regulations of the Department of Agriculture (Continued) AGRICULTURAL MARKETING SERVICE (MARKETING AGREEMENTS... Regulating Handling Olive Administrative Committee § 932.31 Failure to nominate. If nominations for any...

7 CFR 927.25 - Failure to nominate.

Code of Federal Regulations, 2013 CFR

2013-01-01

... 7 Agriculture 8 2013-01-01 2013-01-01 false Failure to nominate. 927.25 Section 927.25 Agriculture Regulations of the Department of Agriculture (Continued) AGRICULTURAL MARKETING SERVICE (MARKETING AGREEMENTS... Order Regulating Handling Administrative Bodies § 927.25 Failure to nominate. In the event nominations...

7 CFR 927.25 - Failure to nominate.

Code of Federal Regulations, 2014 CFR

2014-01-01

... 7 Agriculture 8 2014-01-01 2014-01-01 false Failure to nominate. 927.25 Section 927.25 Agriculture Regulations of the Department of Agriculture (Continued) AGRICULTURAL MARKETING SERVICE (MARKETING AGREEMENTS... Order Regulating Handling Administrative Bodies § 927.25 Failure to nominate. In the event nominations...

Kilometric Continuum Radiation

NASA Technical Reports Server (NTRS)

Green, James L.; Boardsen, Scott

2006-01-01

Kilometric continuum (KC) is the high frequency component (approximately 100 kHz to approximately 800 kHz) of nonthermal continuum (NTC). Unlike the lower frequency portion of NTC (approximately 5 kHz to approximately 100 kHz) whose source is around the dawn sector, the source of KC occurs at all magnetic local times. The latitudinal beaming of KC as observed by GEOTAIL is, for most events, restricted to plus or minus 15 degrees magnetic latitude. KC has been observed during periods of both low and strong geomagnetic activity, with no significant correlation of wave intensity with K(sub p), index. However statistically the maximum observed frequency of KC emission tends to increase with K(sub p) index, the effect is more pronounced around solar maximum, but is also detected near solar minimum. There is strong evidence that the source region of KC is from the equatorial plasmapause during periods when a portion of the plasmapause moves significantly inwards from its nominal position. Case studies have shown that KC emissions are nearly always associated with plasmaspheric notches, shoulders, and tails. There is a recent focus on trying to understand the banded frequency structure of this emission and its relationship to plasmaspheric density ducts and irregularities in the source region.

Separation Control Over A Wall-Mounted Hump

NASA Technical Reports Server (NTRS)

Greenblatt, D.; Paschal, K. B.; Schaeffler, N. W.; Washburn, A. E.; Harris, J.; Yao, C. S.

2007-01-01

Separation control by means of steady suction or zero efflux oscillatory jets is known to be effective in a wide variety of flows under different flow conditions. Control is effective when applied in a nominally two-dimensional manner, for example, at the leading-edge of a wing or at the shoulder of a deflected flap. Despite intuitive understanding of the flow, at present there is no accepted theoretical model that can adequately explain or describe the observed effects of the leading parameters such as reduced suction-rate, or frequency and momentum input. This difficulty stems partly from the turbulent nature of the flows combined with superimposed coherent structures, which are usually driven by at least one instability mechanism. The ever increasing technological importance of these flows has spurned an urgent need to develop turbulence models with a predictive capability. Present attempts to develop such models are hampered in one way or another by incomplete data sets, uncertain or undocumented inflow and boundary conditions, or inadequate flow-field measurements. This paper attempts to address these issues by conducting an experimental investigation of a lowspeed separated flow over a wall-mounted hump model. The model geometry was designed by Seifert & Pack, who measured static and dynamic pressures on the model for a wide range of Reynolds and Mach numbers and control conditions. This paper describes the present experimental setup, as well as the types and range of data acquired. Sample data is presented and future work is discussed.

Characteristics of different frequency ranges in scanning electron microscope images

DOE Office of Scientific and Technical Information (OSTI.GOV)

Sim, K. S., E-mail: kssim@mmu.edu.my; Nia, M. E.; Tan, T. L.

2015-07-22

We demonstrate a new approach to characterize the frequency range in general scanning electron microscope (SEM) images. First, pure frequency images are generated from low frequency to high frequency, and then, the magnification of each type of frequency image is implemented. By comparing the edge percentage of the SEM image to the self-generated frequency images, we can define the frequency ranges of the SEM images. Characterization of frequency ranges of SEM images benefits further processing and analysis of those SEM images, such as in noise filtering and contrast enhancement.

Localizing New Pulsars with Intensity Mapping

NASA Astrophysics Data System (ADS)

Swiggum, Joe; Gentile, Peter

2018-01-01

Although low-frequency, single dish pulsar surveys provide an efficient means of searching large regions of sky quickly, the localization of new discoveries is poor. For example, discoveries from 350 MHz surveys using the Green Bank Telescope (GBT) have position uncertainties up to the FWHM of the telescope's "beam" on the sky, over half a degree! Before finding a coherent timing solution (requires 8-12 months of dedicated timing observations) a "gridding" method is usually employed to improve localization of new pulsars, whereby a grid of higher frequency beam positions is used to tile the initial error region. This method often requires over an hour of observing time to achieve arcminute-precision localization (provided the pulsar is detectable at higher frequencies).Here, we describe another method that uses the same observing frequency as the discovery observation and scans over Right Ascension and Declination directions around the nominal position. A Gaussian beam model is fit to folded pulse profile intensities as a function of time/position to provide improved localization. Using five test cases, we show that intensity mapping localization at 350 MHz with the GBT yields pulsar positions to 1 arcminute precision, facilitating high-frequency follow-up and higher significance detections for future pulsar timing. This method is also well suited to be directly implemented in future low-frequency drift scan pulsar surveys (e.g. with the Five hundred meter Aperture Spherical Telescope; FAST).

Characterization of a gated fiber-optic-coupled detector for application in clinical electron beam dosimetry

DOE Office of Scientific and Technical Information (OSTI.GOV)

Tanyi, James A.; Nitzling, Kevin D.; Lodwick, Camille J.

2011-02-15

Purpose: Assessment of the fundamental dosimetric characteristics of a novel gated fiber-optic-coupled dosimetry system for clinical electron beam irradiation. Methods: The response of fiber-optic-coupled dosimetry system to clinical electron beam, with nominal energy range of 6-20 MeV, was evaluated for reproducibility, linearity, and output dependence on dose rate, dose per pulse, energy, and field size. The validity of the detector system's response was assessed in correspondence with a reference ionization chamber. Results: The fiber-optic-coupled dosimetry system showed little dependence to dose rate variations (coefficient of variation {+-}0.37%) and dose per pulse changes (with 0.54% of reference chamber measurements). The reproducibilitymore » of the system was {+-}0.55% for dose fractions of {approx}100 cGy. Energy dependence was within {+-}1.67% relative to the reference ionization chamber for the 6-20 MeV nominal electron beam energy range. The system exhibited excellent linear response (R{sup 2}=1.000) compared to reference ionization chamber in the dose range of 1-1000 cGy. The output factors were within {+-}0.54% of the corresponding reference ionization chamber measurements. Conclusions: The dosimetric properties of the gated fiber-optic-coupled dosimetry system compare favorably to the corresponding reference ionization chamber measurements and show considerable potential for applications in clinical electron beam radiotherapy.« less

Aerothermal evaluation of a spherically blunted body with a trapezoidal cross section in the Langley 8-foot high-temperature tunnel

NASA Technical Reports Server (NTRS)

Albertson, Cindy W.

1987-01-01

A model to be used in the flow studies and curved Thermal Protection System (TPS) evaluations was tested in the Langley 8 Foot High-Temperature Tunnel at a nominal Mach number of 6.8. The purpose of the study was to define the surface pressure and heating rates at high angles of attack (in support of curved metallic TPS studies) and to determine the conditions for which the model would be suitable as a test bed for aerothermal load studies. The present study was conducted at a nominal total temperature of 2400 and 3300 R, dynamic pressures from 2.3 to 10.9 psia, and free-stream Reynolds numbers from 4000,000 to 1,700,000/ft. The measurements consisted primarily of surface pressure and cold-wall (530 R) heating rates. Qualitative comparisons between predictions and data show that for this configuration, aerothermal tests should be limited to angles of attack between 10 and -10 degrees. Outside this range, the effects of free-stream flow nonuniformity appear in the data, as a result of the long length of the model. However, for TPS testing, this is not a concern and tests can be performed at angles of attack ranging from 20 to -20 degrees. Laminar and naturally turbulent boundary layers are available over limited ranges of conditions.

75 FR 44793 - Consumer Advisory Council Solicitation of Nominations for Membership

Federal Register 2010, 2011, 2012, 2013, 2014

2010-07-29

... to nominate qualified individuals for appointment to its Consumer Advisory Council, whose membership... affiliation, title, address, phone and fax numbers, and e-mail address. Individuals may nominate themselves... does not limit consideration to individuals nominated by the public when making its selection. Council...

36 CFR 60.11 - Requests for nominations.

Code of Federal Regulations, 2010 CFR

2010-07-01

... and appears to meet the National Register criteria for evaluation in § 60.4. If the nomination form is... any person or organization submitting a completed National Register nomination form or requesting consideration for any previously prepared nomination form on record with the State or Federal agency. The...

7 CFR 1219.34 - Failure to nominate.

Code of Federal Regulations, 2012 CFR

2012-01-01

... 7 Agriculture 10 2012-01-01 2012-01-01 false Failure to nominate. 1219.34 Section 1219.34 Agriculture Regulations of the Department of Agriculture (Continued) AGRICULTURAL MARKETING SERVICE (MARKETING....34 Failure to nominate. In any case in which producers or importers fail to nominate individuals for...

7 CFR 915.24 - Failure to nominate.

Code of Federal Regulations, 2014 CFR

2014-01-01

... 7 Agriculture 8 2014-01-01 2014-01-01 false Failure to nominate. 915.24 Section 915.24 Agriculture Regulations of the Department of Agriculture (Continued) AGRICULTURAL MARKETING SERVICE (MARKETING AGREEMENTS... Regulating Handling Administrative Body § 915.24 Failure to nominate. If nominations are not made within the...

7 CFR 915.24 - Failure to nominate.

Code of Federal Regulations, 2011 CFR

2011-01-01

... 7 Agriculture 8 2011-01-01 2011-01-01 false Failure to nominate. 915.24 Section 915.24 Agriculture Regulations of the Department of Agriculture (Continued) AGRICULTURAL MARKETING SERVICE (Marketing Agreements... Regulating Handling Administrative Body § 915.24 Failure to nominate. If nominations are not made within the...

7 CFR 1219.34 - Failure to nominate.

Code of Federal Regulations, 2013 CFR

2013-01-01

... 7 Agriculture 10 2013-01-01 2013-01-01 false Failure to nominate. 1219.34 Section 1219.34 Agriculture Regulations of the Department of Agriculture (Continued) AGRICULTURAL MARKETING SERVICE (MARKETING....34 Failure to nominate. In any case in which producers or importers fail to nominate individuals for...

7 CFR 915.24 - Failure to nominate.

Code of Federal Regulations, 2013 CFR

2013-01-01

... 7 Agriculture 8 2013-01-01 2013-01-01 false Failure to nominate. 915.24 Section 915.24 Agriculture Regulations of the Department of Agriculture (Continued) AGRICULTURAL MARKETING SERVICE (MARKETING AGREEMENTS... Regulating Handling Administrative Body § 915.24 Failure to nominate. If nominations are not made within the...

7 CFR 948.57 - Failure to nominate.

Code of Federal Regulations, 2014 CFR

2014-01-01

... 7 Agriculture 8 2014-01-01 2014-01-01 false Failure to nominate. 948.57 Section 948.57 Agriculture Regulations of the Department of Agriculture (Continued) AGRICULTURAL MARKETING SERVICE (MARKETING AGREEMENTS... Order Regulating Handling Committees § 948.57 Failure to nominate. If nominations are not made pursuant...

7 CFR 948.57 - Failure to nominate.

Code of Federal Regulations, 2013 CFR

2013-01-01

... 7 Agriculture 8 2013-01-01 2013-01-01 false Failure to nominate. 948.57 Section 948.57 Agriculture Regulations of the Department of Agriculture (Continued) AGRICULTURAL MARKETING SERVICE (MARKETING AGREEMENTS... Order Regulating Handling Committees § 948.57 Failure to nominate. If nominations are not made pursuant...

7 CFR 948.57 - Failure to nominate.

Code of Federal Regulations, 2010 CFR

2010-01-01

... 7 Agriculture 8 2010-01-01 2010-01-01 false Failure to nominate. 948.57 Section 948.57 Agriculture Regulations of the Department of Agriculture (Continued) AGRICULTURAL MARKETING SERVICE (Marketing Agreements... Order Regulating Handling Committees § 948.57 Failure to nominate. If nominations are not made pursuant...

7 CFR 1219.34 - Failure to nominate.

Code of Federal Regulations, 2011 CFR

2011-01-01

... 7 Agriculture 10 2011-01-01 2011-01-01 false Failure to nominate. 1219.34 Section 1219.34 Agriculture Regulations of the Department of Agriculture (Continued) AGRICULTURAL MARKETING SERVICE (MARKETING....34 Failure to nominate. In any case in which producers or importers fail to nominate individuals for...

7 CFR 916.24 - Failure to nominate.

Code of Federal Regulations, 2011 CFR

2011-01-01

... 7 Agriculture 8 2011-01-01 2011-01-01 false Failure to nominate. 916.24 Section 916.24 Agriculture Regulations of the Department of Agriculture (Continued) AGRICULTURAL MARKETING SERVICE (Marketing Agreements... Regulating Handling Administrative Body § 916.24 Failure to nominate. If nominations are not made within the...

7 CFR 916.24 - Failure to nominate.

Code of Federal Regulations, 2010 CFR

2010-01-01

... 7 Agriculture 8 2010-01-01 2010-01-01 false Failure to nominate. 916.24 Section 916.24 Agriculture Regulations of the Department of Agriculture (Continued) AGRICULTURAL MARKETING SERVICE (Marketing Agreements... Regulating Handling Administrative Body § 916.24 Failure to nominate. If nominations are not made within the...

7 CFR 948.57 - Failure to nominate.

Code of Federal Regulations, 2011 CFR

2011-01-01

... 7 Agriculture 8 2011-01-01 2011-01-01 false Failure to nominate. 948.57 Section 948.57 Agriculture Regulations of the Department of Agriculture (Continued) AGRICULTURAL MARKETING SERVICE (Marketing Agreements... Order Regulating Handling Committees § 948.57 Failure to nominate. If nominations are not made pursuant...

7 CFR 948.57 - Failure to nominate.

Code of Federal Regulations, 2012 CFR

2012-01-01

... 7 Agriculture 8 2012-01-01 2012-01-01 false Failure to nominate. 948.57 Section 948.57 Agriculture Regulations of the Department of Agriculture (Continued) AGRICULTURAL MARKETING SERVICE (Marketing Agreements... Order Regulating Handling Committees § 948.57 Failure to nominate. If nominations are not made pursuant...

7 CFR 1219.34 - Failure to nominate.

Code of Federal Regulations, 2014 CFR

2014-01-01

... 7 Agriculture 10 2014-01-01 2014-01-01 false Failure to nominate. 1219.34 Section 1219.34 Agriculture Regulations of the Department of Agriculture (Continued) AGRICULTURAL MARKETING SERVICE (MARKETING....34 Failure to nominate. In any case in which producers or importers fail to nominate individuals for...

7 CFR 915.24 - Failure to nominate.

Code of Federal Regulations, 2012 CFR

2012-01-01

... 7 Agriculture 8 2012-01-01 2012-01-01 false Failure to nominate. 915.24 Section 915.24 Agriculture Regulations of the Department of Agriculture (Continued) AGRICULTURAL MARKETING SERVICE (Marketing Agreements... Regulating Handling Administrative Body § 915.24 Failure to nominate. If nominations are not made within the...

Neutron detector using lithiated glass-scintillating particle composite

DOEpatents

Wallace, Steven [Knoxville, TN; Stephan, Andrew C [Knoxville, TX; Dai, Sheng [Knoxville, TN; Im, Hee-Jung [Knoxville, TN

2009-09-01

A neutron detector composed of a matrix of scintillating particles imbedded in a lithiated glass is disclosed. The neutron detector detects the neutrons by absorbing the neutron in the lithium-6 isotope which has been enriched from the natural isotopic ratio to a commercial ninety five percent. The utility of the detector is optimized by suitably selecting scintillating particle sizes in the range of the alpha and the triton. Nominal particle sizes are in the range of five to twenty five microns depending upon the specific scintillating particle selected.

A contribution to ULF activity in the Pc 3-4 range correlated with IMF radial orientation. [geomagnetic micropulsations

NASA Technical Reports Server (NTRS)

Greenstadt, E. W.; Olson, J. V.

1977-01-01

The paper describes an experiment to determine whether the radial orientation of the interplanetary magnetic field (IMF) is associated with ULF activity in the Pc 3-4 range. Data are obtained from base levels, undisturbed intervals, IMF and disturbance selection, and trigonometric correlation. The results obtained are discussed, noting particularly that for low Kp, the probability of enhanced amplitude noise rises as IMF orientation with respect to the nominal solar wind flow decreases in both Pc 3 and Pc 4 channels.

Sensitivity of transport aircraft performance and economics to advanced technology and cruise Mach number

NASA Technical Reports Server (NTRS)

Ardema, M. D.

1974-01-01

Sensitivity data for advanced technology transports has been systematically collected. This data has been generated in two separate studies. In the first of these, three nominal, or base point, vehicles designed to cruise at Mach numbers .85, .93, and .98, respectively, were defined. The effects on performance and economics of perturbations to basic parameters in the areas of structures, aerodynamics, and propulsion were then determined. In all cases, aircraft were sized to meet the same payload and range as the nominals. This sensitivity data may be used to assess the relative effects of technology changes. The second study was an assessment of the effect of cruise Mach number. Three families of aircraft were investigated in the Mach number range 0.70 to 0.98: straight wing aircraft from 0.70 to 0.80; sweptwing, non-area ruled aircraft from 0.80 to 0.95; and area ruled aircraft from 0.90 to 0.98. At each Mach number, the values of wing loading, aspect ratio, and bypass ratio which resulted in minimum gross takeoff weight were used. As part of the Mach number study, an assessment of the effect of increased fuel costs was made.

Prediction of the Creep-Fatigue Lifetime of Alloy 617: An Application of Non-destructive Evaluation and Information Integration

DOE Office of Scientific and Technical Information (OSTI.GOV)

Vivek Agarwal; Richard Wright; Timothy Roney

A relatively simple method using the nominal constant average stress information and the creep rupture model is developed to predict the creep-fatigue lifetime of Alloy 617, in terms of time to rupture. The nominal constant average stress is computed using the stress relaxation curve. The predicted time to rupture can be converted to number of cycles to failure using the strain range, the strain rate during each cycle, and the hold time information. The predicted creep-fatigue lifetime is validated against the experimental measurements of the creep-fatigue lifetime collected using conventional laboratory creep-fatigue tests. High temperature creep-fatigue tests of Alloy 617more » were conducted in air at 950°C with a tensile hold period of up to 1800s in a cycle at total strain ranges of 0.3% and 0.6%. It was observed that the proposed method is conservative in that the predicted lifetime is less than the experimentally determined values. The approach would be relevant to calculate the remaining useful life to a component like a steam generator that might fail by the creep-fatigue mechanism.« less

Transparent conducting oxide nanotubes

NASA Astrophysics Data System (ADS)

Alivov, Yahya; Singh, Vivek; Ding, Yuchen; Nagpal, Prashant

2014-09-01

Thin film or porous membranes made of hollow, transparent, conducting oxide (TCO) nanotubes, with high chemical stability, functionalized surfaces and large surface areas, can provide an excellent platform for a wide variety of nanostructured photovoltaic, photodetector, photoelectrochemical and photocatalytic devices. While large-bandgap oxide semiconductors offer transparency for incident light (below their nominal bandgap), their low carrier concentration and poor conductivity makes them unsuitable for charge conduction. Moreover, materials with high conductivity have nominally low bandgaps and hence poor light transmittance. Here, we demonstrate thin films and membranes made from TiO2 nanotubes heavily-doped with shallow Niobium (Nb) donors (up to 10%, without phase segregation), using a modified electrochemical anodization process, to fabricate transparent conducting hollow nanotubes. Temperature dependent current-voltage characteristics revealed that TiO2 TCO nanotubes, doped with 10% Nb, show metal-like behavior with resistivity decreasing from 6.5 × 10-4 Ωcm at T = 300 K (compared to 6.5 × 10-1 Ωcm for nominally undoped nanotubes) to 2.2 × 10-4 Ωcm at T = 20 K. Optical properties, studied by reflectance measurements, showed light transmittance up to 90%, within wavelength range 400 nm-1000 nm. Nb doping also improves the field emission properties of TCO nanotubes demonstrating an order of magnitude increase in field-emitter current, compared to undoped samples.

Does an aggressor's target choice matter? Assessing change in the social network prestige of aggressive youth.

PubMed

Andrews, Naomi C Z; Hanish, Laura D; Santos, Carlos E

2017-07-01

Based on a social dominance approach, aggression is conceptualized as a strategy used to gain position, power, and influence within the peer network. However, aggression may only be beneficial when targeted against particular peers; both victims' social standing and the number of victims targeted may impact aggressors' social standing. The current study examined associations between aggressors' targeting tendencies (victims' social standing and number of victims) and aggressors' own social standing, both concurrently and over time. Analyses were conducted using three analytic samples of seventh and eighth grade aggressors (Ns ranged from 161 to 383, 49% girls; 50% Latina/o). Participants nominated their friends; nominations were used to calculate social network prestige. Peer nominations were used to identify aggressors and their victim(s). For each aggressor, number of victims and victims' social network prestige were assessed. Aggressors with more victims and with highly prestigious victims had higher social network prestige themselves, and they increased more in prestige over time than aggressors with fewer victims and less prestigious victims (though there were some differences across analytic samples). Findings have implications for the need to extend the social dominance approach to better address the links between aggressors and victims. Aggr. Behav. 43:364-374, 2017. © 2017 Wiley Periodicals, Inc. © 2017 Wiley Periodicals, Inc.

Performance metrics for Inertial Confinement Fusion implosions: aspects of the technical framework for measuring progress in the National Ignition Campaign

DOE Office of Scientific and Technical Information (OSTI.GOV)

Spears, B K; Glenzer, S; Edwards, M J

The National Ignition Campaign (NIC) uses non-igniting 'THD' capsules to study and optimize the hydrodynamic assembly of the fuel without burn. These capsules are designed to simultaneously reduce DT neutron yield and to maintain hydrodynamic similarity with the DT ignition capsule. We will discuss nominal THD performance and the associated experimental observables. We will show the results of large ensembles of numerical simulations of THD and DT implosions and their simulated diagnostic outputs. These simulations cover a broad range of both nominal and off nominal implosions. We will focus on the development of an experimental implosion performance metric called themore » experimental ignition threshold factor (ITFX). We will discuss the relationship between ITFX and other integrated performance metrics, including the ignition threshold factor (ITF), the generalized Lawson criterion (GLC), and the hot spot pressure (HSP). We will then consider the experimental results of the recent NIC THD campaign. We will show that we can observe the key quantities for producing a measured ITFX and for inferring the other performance metrics. We will discuss trends in the experimental data, improvement in ITFX, and briefly the upcoming tuning campaign aimed at taking the next steps in performance improvement on the path to ignition on NIF.« less

Performance metrics for inertial confinement fusion implosions: Aspects of the technical framework for measuring progress in the National Ignition Campaign

DOE Office of Scientific and Technical Information (OSTI.GOV)

Spears, Brian K.; Glenzer, S.; Edwards, M. J.

The National Ignition Campaign (NIC) uses non-igniting 'tritium hydrogen deuterium (THD)' capsules to study and optimize the hydrodynamic assembly of the fuel without burn. These capsules are designed to simultaneously reduce DT neutron yield and to maintain hydrodynamic similarity with the DT ignition capsule. We will discuss nominal THD performance and the associated experimental observables. We will show the results of large ensembles of numerical simulations of THD and DT implosions and their simulated diagnostic outputs. These simulations cover a broad range of both nominal and off-nominal implosions. We will focus on the development of an experimental implosion performance metricmore » called the experimental ignition threshold factor (ITFX). We will discuss the relationship between ITFX and other integrated performance metrics, including the ignition threshold factor (ITF), the generalized Lawson criterion (GLC), and the hot spot pressure (HSP). We will then consider the experimental results of the recent NIC THD campaign. We will show that we can observe the key quantities for producing a measured ITFX and for inferring the other performance metrics. We will discuss trends in the experimental data, improvement in ITFX, and briefly the upcoming tuning campaign aimed at taking the next steps in performance improvement on the path to ignition on NIF.« less

Use of a Teacher Nomination Strategy to Screen for Autism Spectrum Disorders in General Education Classrooms: A Pilot Study

PubMed Central

Hepburn, Susan L.; DiGuiseppi, Carolyn; Rosenberg, Steven; Kaparich, Kristina; Robinson, Cordelia; Miller, Lisa

2015-01-01

Given a rising prevalence of autism spectrum disorders (ASD), this project aimed to develop and pilot test various teacher nomination strategies to identify children at risk for ASD in a timely, reliable, cost-effective manner. Sixty participating elementary school teachers evaluated 1323 children in total. Each teacher nominated students who most fit a description of ASD-associated characteristics, and completed the Autism Syndrome Screening Questionnaire (ASSQ) on every child in the classroom. The proportion of overall agreement between teacher nomination and ASSQ was 93–95%, depending upon the nomination parameters. Nomination required 15 min per class versus 3.5–5.5 h per class for the ASSQ. These results support the need for further study of teacher nomination strategies to identify children at risk for ASD. PMID:17661165

Systems design and analysis of the microwave radiometer spacecraft

NASA Technical Reports Server (NTRS)

Garrett, L. B.

1981-01-01

Systems design and analysis data were generated for microwave radiometer spacecraft concept using the Large Advanced Space Systems (LASS) computer aided design and analysis program. Parametric analyses were conducted for perturbations off the nominal-orbital-altitude/antenna-reflector-size and for control/propulsion system options. Optimized spacecraft mass, structural element design, and on-orbit loading data are presented. Propulsion and rigid-body control systems sensitivities to current and advanced technology are established. Spacecraft-induced and environmental effects on antenna performance (surface accuracy, defocus, and boresight off-set) are quantified and structured material frequencies and modal shapes are defined.

Theory versus experiment for the rotordynamic coefficients of annular gas seals. I - Test facility and apparatus

NASA Technical Reports Server (NTRS)

Childs, D. W.; Nelson, C. E.; Nicks, C.; Scharrer, J.; Elrod, D.

1985-01-01

A facility and apparatus are described for determining the rotordynamic coefficients and leakage characteristics of annular gas seals. The coefficients and leakage characteristics of annular gas seals. The apparatus has a current top speed of 8000 cpm with a nominal seal diameter of 15.24 cmn (6 in.). The air supply unit yields a seal pressure ratio of approximately 7. An external shaker is used to excite the test rotor. The capability to independently calculate all rotordynamic coefficients at a given operating condition with one excitation frequency are discussed.

A Comprehensive Robust Adaptive Controller for Gust Load Alleviation

PubMed Central

Quagliotti, Fulvia

2014-01-01

The objective of this paper is the implementation and validation of an adaptive controller for aircraft gust load alleviation. The contribution of this paper is the design of a robust controller that guarantees the reduction of the gust loads, even when the nominal conditions change. Some preliminary results are presented, considering the symmetric aileron deflection as control device. The proposed approach is validated on subsonic transport aircraft for different mass and flight conditions. Moreover, if the controller parameters are tuned for a specific gust model, even if the gust frequency changes, no parameter retuning is required. PMID:24688411

Helium refrigeration considerations for cryomodule design

DOE Office of Scientific and Technical Information (OSTI.GOV)

Ganni, V.; Knudsen, P.

Many of the present day accelerators are based on superconducting radio frequency (SRF) cavities, packaged in cryo-modules (CM), which depend on helium refrigeration at sub-atmospheric pressures, nominally 2 K. These specialized helium refrigeration systems are quite cost intensive to produce and operate. Particularly as there is typically no work extraction below the 4.5-K supply, it is important that the exergy loss between this temperature level and the CM load temperature(s) be minimized by the process configuration choices. This paper will present, compare and discuss several possible helium distribution process arrangements to support the CM loads.

Fixed order dynamic compensation for multivariable linear systems

NASA Technical Reports Server (NTRS)

Kramer, F. S.; Calise, A. J.

1986-01-01

This paper considers the design of fixed order dynamic compensators for multivariable time invariant linear systems, minimizing a linear quadratic performance cost functional. Attention is given to robustness issues in terms of multivariable frequency domain specifications. An output feedback formulation is adopted by suitably augmenting the system description to include the compensator states. Either a controller or observer canonical form is imposed on the compensator description to reduce the number of free parameters to its minimal number. The internal structure of the compensator is prespecified by assigning a set of ascending feedback invariant indices, thus forming a Brunovsky structure for the nominal compensator.

24 CFR 598.205 - What are the requirements for nomination?

Code of Federal Regulations, 2013 CFR

2013-04-01

... nomination? 598.205 Section 598.205 Housing and Urban Development Regulations Relating to Housing and Urban... DESIGNATIONS Nomination Procedure § 598.205 What are the requirements for nomination? (a) General. No urban... that the strategic plan described in § 598.215 will be implemented, and these governments submit its...

24 CFR 598.205 - What are the requirements for nomination?

Code of Federal Regulations, 2012 CFR

2012-04-01

... nomination? 598.205 Section 598.205 Housing and Urban Development Regulations Relating to Housing and Urban... DESIGNATIONS Nomination Procedure § 598.205 What are the requirements for nomination? (a) General. No urban... that the strategic plan described in § 598.215 will be implemented, and these governments submit its...

24 CFR 598.205 - What are the requirements for nomination?

Code of Federal Regulations, 2014 CFR

2014-04-01

... nomination? 598.205 Section 598.205 Housing and Urban Development Regulations Relating to Housing and Urban... DESIGNATIONS Nomination Procedure § 598.205 What are the requirements for nomination? (a) General. No urban... that the strategic plan described in § 598.215 will be implemented, and these governments submit its...

76 FR 71566 - Solicitation of Nominations for Membership on the National Vaccine Advisory Committee

Federal Register 2010, 2011, 2012, 2013, 2014

2011-11-18

...., Public Health Advisor, National Vaccine Program Office, Department of Health and Human Services, 200... vacated during the calendar year 2012. Nominations In accordance with the charter, persons nominated for... information should be included in the package of material submitted for each individual being nominated for...

78 FR 31939 - Solicitation of Nominations for Membership on the National Vaccine Advisory Committee

Federal Register 2010, 2011, 2012, 2013, 2014

2013-05-28

...., Public Health Advisor, National Vaccine Program Office, Department of Health and Human Services, 200... vacated during the calendar year 2013. Nominations In accordance with the charter, persons nominated for... information should be included in the package of material submitted for each individual being nominated for...

7 CFR 25.502 - Nominations by State-chartered economic development corporations.

Code of Federal Regulations, 2010 CFR

2010-01-01

... 7 Agriculture 1 2010-01-01 2010-01-01 false Nominations by State-chartered economic development... AND ENTERPRISE COMMUNITIES Special Rules § 25.502 Nominations by State-chartered economic development corporations. Any rural area nominated by an economic development corporation chartered by a State and...

75 FR 28782 - Extension of Period for Nominations to the National Medal of Technology and Innovation Nomination...

Federal Register 2010, 2011, 2012, 2013, 2014

2010-05-24

... innovation and/or be familiar with the education, training, employment and management of technological... Innovations/Bioengineering and Biomedical Technology; Technology Management/Computing/IT/Manufacturing...] Extension of Period for Nominations to the National Medal of Technology and Innovation Nomination Evaluation...

Exploring Reference Group Effects on Teachers' Nominations of Gifted Students

ERIC Educational Resources Information Center

Rothenbusch, Sandra; Zettler, Ingo; Voss, Thamar; Lösch, Thomas; Trautwein, Ulrich

2016-01-01

Teachers are often asked to nominate students for enrichment programs for gifted children, and studies have repeatedly indicated that students' intelligence is related to their likelihood of being nominated as gifted. However, it is unknown whether class-average levels of intelligence influence teachers' nominations as suggested by theory--and…

Trajectories of Peer-Nominated Aggression: Risk Status, Predictors and Outcomes.

ERIC Educational Resources Information Center

van Lier, Pol A.C.; Crijnen, Alfons A.M.

2005-01-01

Developmental trajectories of peer-nominated aggression, risk factors at baseline, and outcomes were studied. Peer nominations of aggression were obtained annually from grades 1 to 3. Three developmental trajectories were identified: an early-onset/increasers trajectory with high levels of peer-nominated aggression at elementary school entry and…

36 CFR 60.10 - Concurrent State and Federal nominations.

Code of Federal Regulations, 2010 CFR

2010-07-01

... cultural value. Federal agencies may nominate properties where a portion of the property is not under Federal ownership or control. (b) When a portion of the area included in a Federal nomination is not... cultural resource, the completed nomination form shall be sent to the State Historic Preservation Officer...

45 CFR 1801.10 - Nomination by institution of higher education.

Code of Federal Regulations, 2013 CFR

2013-10-01

... 45 Public Welfare 4 2013-10-01 2013-10-01 false Nomination by institution of higher education. 1801.10 Section 1801.10 Public Welfare Regulations Relating to Public Welfare (Continued) HARRY S. TRUMAN SCHOLARSHIP FOUNDATION HARRY S. TRUMAN SCHOLARSHIP PROGRAM Nominations § 1801.10 Nomination by...

45 CFR 1801.11 - Annual nomination.

Code of Federal Regulations, 2011 CFR

2011-10-01

... 45 Public Welfare 4 2011-10-01 2011-10-01 false Annual nomination. 1801.11 Section 1801.11 Public Welfare Regulations Relating to Public Welfare (Continued) HARRY S. TRUMAN SCHOLARSHIP FOUNDATION HARRY S. TRUMAN SCHOLARSHIP PROGRAM Nominations § 1801.11 Annual nomination. (a) Except as provided in §§ 1801.11...

45 CFR 1801.11 - Annual nomination.

Code of Federal Regulations, 2014 CFR

2014-10-01

... 45 Public Welfare 4 2014-10-01 2014-10-01 false Annual nomination. 1801.11 Section 1801.11 Public Welfare Regulations Relating to Public Welfare (Continued) HARRY S. TRUMAN SCHOLARSHIP FOUNDATION HARRY S. TRUMAN SCHOLARSHIP PROGRAM Nominations § 1801.11 Annual nomination. (a) Except as provided in §§ 1801.11...

45 CFR 1801.11 - Annual nomination.

Code of Federal Regulations, 2013 CFR

2013-10-01

... 45 Public Welfare 4 2013-10-01 2013-10-01 false Annual nomination. 1801.11 Section 1801.11 Public Welfare Regulations Relating to Public Welfare (Continued) HARRY S. TRUMAN SCHOLARSHIP FOUNDATION HARRY S. TRUMAN SCHOLARSHIP PROGRAM Nominations § 1801.11 Annual nomination. (a) Except as provided in §§ 1801.11...

45 CFR 1801.10 - Nomination by institution of higher education.

Code of Federal Regulations, 2011 CFR

2011-10-01

... 45 Public Welfare 4 2011-10-01 2011-10-01 false Nomination by institution of higher education. 1801.10 Section 1801.10 Public Welfare Regulations Relating to Public Welfare (Continued) HARRY S. TRUMAN SCHOLARSHIP FOUNDATION HARRY S. TRUMAN SCHOLARSHIP PROGRAM Nominations § 1801.10 Nomination by...

45 CFR 1801.10 - Nomination by institution of higher education.

Code of Federal Regulations, 2014 CFR

2014-10-01

... 45 Public Welfare 4 2014-10-01 2014-10-01 false Nomination by institution of higher education. 1801.10 Section 1801.10 Public Welfare Regulations Relating to Public Welfare (Continued) HARRY S. TRUMAN SCHOLARSHIP FOUNDATION HARRY S. TRUMAN SCHOLARSHIP PROGRAM Nominations § 1801.10 Nomination by...

45 CFR 1801.11 - Annual nomination.

Code of Federal Regulations, 2010 CFR

2010-10-01

... 45 Public Welfare 4 2010-10-01 2010-10-01 false Annual nomination. 1801.11 Section 1801.11 Public Welfare Regulations Relating to Public Welfare (Continued) HARRY S. TRUMAN SCHOLARSHIP FOUNDATION HARRY S. TRUMAN SCHOLARSHIP PROGRAM Nominations § 1801.11 Annual nomination. (a) Except as provided in §§ 1801.11...

45 CFR 1801.11 - Annual nomination.

Code of Federal Regulations, 2012 CFR

2012-10-01

... 45 Public Welfare 4 2012-10-01 2012-10-01 false Annual nomination. 1801.11 Section 1801.11 Public Welfare Regulations Relating to Public Welfare (Continued) HARRY S. TRUMAN SCHOLARSHIP FOUNDATION HARRY S. TRUMAN SCHOLARSHIP PROGRAM Nominations § 1801.11 Annual nomination. (a) Except as provided in §§ 1801.11...

45 CFR 1801.10 - Nomination by institution of higher education.

Code of Federal Regulations, 2012 CFR

2012-10-01

... 45 Public Welfare 4 2012-10-01 2012-10-01 false Nomination by institution of higher education. 1801.10 Section 1801.10 Public Welfare Regulations Relating to Public Welfare (Continued) HARRY S. TRUMAN SCHOLARSHIP FOUNDATION HARRY S. TRUMAN SCHOLARSHIP PROGRAM Nominations § 1801.10 Nomination by...

7 CFR 25.502 - Nominations by State-chartered economic development corporations.

Code of Federal Regulations, 2013 CFR

2013-01-01

... 7 Agriculture 1 2013-01-01 2013-01-01 false Nominations by State-chartered economic development... AND ENTERPRISE COMMUNITIES Special Rules § 25.502 Nominations by State-chartered economic development corporations. Any rural area nominated by an economic development corporation chartered by a State and...

7 CFR 25.502 - Nominations by State-chartered economic development corporations.

Code of Federal Regulations, 2014 CFR

2014-01-01

... 7 Agriculture 1 2014-01-01 2014-01-01 false Nominations by State-chartered economic development... AND ENTERPRISE COMMUNITIES Special Rules § 25.502 Nominations by State-chartered economic development corporations. Any rural area nominated by an economic development corporation chartered by a State and...

7 CFR 25.502 - Nominations by State-chartered economic development corporations.

Code of Federal Regulations, 2011 CFR

2011-01-01

... 7 Agriculture 1 2011-01-01 2011-01-01 false Nominations by State-chartered economic development... AND ENTERPRISE COMMUNITIES Special Rules § 25.502 Nominations by State-chartered economic development corporations. Any rural area nominated by an economic development corporation chartered by a State and...

7 CFR 25.502 - Nominations by State-chartered economic development corporations.

Code of Federal Regulations, 2012 CFR

2012-01-01

... 7 Agriculture 1 2012-01-01 2012-01-01 false Nominations by State-chartered economic development... AND ENTERPRISE COMMUNITIES Special Rules § 25.502 Nominations by State-chartered economic development corporations. Any rural area nominated by an economic development corporation chartered by a State and...

77 FR 48168 - Call for Nominations for the Twin Falls District Resource Advisory Council

Federal Register 2010, 2011, 2012, 2013, 2014

2012-08-13

... for Nominations for the Twin Falls District Resource Advisory Council AGENCY: Bureau of Land Management, Interior. ACTION: Call for Nominations, Twin Falls District Resource Advisory Council SUMMARY: This notice requests public nominations to fill one position on the Twin Falls District Resource...

75 FR 69631 - National Medal of Technology and Innovation Nomination Evaluation Committee Meeting

Federal Register 2010, 2011, 2012, 2013, 2014

2010-11-15

... selection. NMTI Nomination Evaluation Committee members are drawn from both the public and private sectors... Technology and Innovation Nomination Evaluation Committee Meeting AGENCY: United States Patent and Trademark... Innovation (NMTI) Nomination Evaluation Committee will meet in closed session on Tuesday, November 30, 2010...

7 CFR 930.25 - Failure to nominate.

Code of Federal Regulations, 2012 CFR

2012-01-01

... 7 Agriculture 8 2012-01-01 2012-01-01 false Failure to nominate. 930.25 Section 930.25 Agriculture Regulations of the Department of Agriculture (Continued) AGRICULTURAL MARKETING SERVICE (Marketing Agreements... Administrative Body § 930.25 Failure to nominate. If nominations are not made within the time and in the manner...

7 CFR 959.28 - Failure to nominate.

Code of Federal Regulations, 2012 CFR

2012-01-01

... 7 Agriculture 8 2012-01-01 2012-01-01 false Failure to nominate. 959.28 Section 959.28 Agriculture Regulations of the Department of Agriculture (Continued) AGRICULTURAL MARKETING SERVICE (Marketing Agreements... Regulating Handling Committee § 959.28 Failure to nominate. If nominations are not made within the time and...

7 CFR 959.28 - Failure to nominate.

Code of Federal Regulations, 2010 CFR

2010-01-01

... 7 Agriculture 8 2010-01-01 2010-01-01 false Failure to nominate. 959.28 Section 959.28 Agriculture Regulations of the Department of Agriculture (Continued) AGRICULTURAL MARKETING SERVICE (Marketing Agreements... Regulating Handling Committee § 959.28 Failure to nominate. If nominations are not made within the time and...