The application of magnetic measurements for the characterization of atmospheric particulate pollution within the airport environment.

PubMed

Jones, S; Richardson, N; Bennett, M; Hoon, S R

2015-01-01

The significant increase in global air travel which has occurred during the last fifty years has generated growing concern regarding the potential impacts associated with increasing emissions of atmospheric particulate matter (PM) on health and the environment. PM within the airport environment may be derived from a range of sources. To date, however, the identification of individual sources of airport derived PM has remained elusive but constitutes a research priority for the aviation industry.The aim of this research was to identify distinctive and characteristic fingerprints of atmospheric PM derived from various sources in an airport environment through the use of environmental magnetic measurements. PM samples from aircraft engine emissions, brake wear and tire wear residues have been obtained from a range of different aircraft and engine types. Samples have been analyzed utilizing a range of magnetic mineral properties indicative of magnetic mineralogy and grain size. Results indicate that the dusts from the three 'aircraft' sources, (i.e. engines, brakes and tires) display distinctive magnetic mineral characteristics which may serve as 'magnetic fingerprints' for these sources. Magnetic measurements of runway dusts collected at different locations on the runway surface also show contrasting magnetic characteristics which, when compared with those of the aircraft-derived samples, suggest that they may relate to different sources characteristic of aircraft emissions at various stages of the take-off/landing cycle. The findings suggest that magnetic measurements could have wider applicability for the differentiation and identification of PM within the airport environment.

Source levels of social sounds in migrating humpback whales (Megaptera novaeangliae).

PubMed

Dunlop, Rebecca A; Cato, Douglas H; Noad, Michael J; Stokes, Dale M

2013-07-01

The source level of an animal sound is important in communication, since it affects the distance over which the sound is audible. Several measurements of source levels of whale sounds have been reported, but the accuracy of many is limited because the distance to the source and the acoustic transmission loss were estimated rather than measured. This paper presents measurements of source levels of social sounds (surface-generated and vocal sounds) of humpback whales from a sample of 998 sounds recorded from 49 migrating humpback whale groups. Sources were localized using a wide baseline five hydrophone array and transmission loss was measured for the site. Social vocalization source levels were found to range from 123 to 183 dB re 1 μPa @ 1 m with a median of 158 dB re 1 μPa @ 1 m. Source levels of surface-generated social sounds ("breaches" and "slaps") were narrower in range (133 to 171 dB re 1 μPa @ 1 m) but slightly higher in level (median of 162 dB re 1 μPa @ 1 m) compared to vocalizations. The data suggest that group composition has an effect on group vocalization source levels in that singletons and mother-calf-singing escort groups tend to vocalize at higher levels compared to other group compositions.

Radio polarization properties of quasars and active galaxies at high redshifts

NASA Astrophysics Data System (ADS)

Vernstrom, T.; Gaensler, B. M.; Vacca, V.; Farnes, J. S.; Haverkorn, M.; O'Sullivan, S. P.

2018-04-01

We present the largest ever sample of radio polarization properties for z > 4 sources, with 14 sources having significant polarization detections. Using wide-band data from the Karl G. Jansky Very Large Array, we obtained the rest-frame total intensity and polarization properties of 37 radio sources, nine of which have spectroscopic redshifts in the range 1 ≤ z ≤ 1.4, with the other 28 having spectroscopic redshifts in the range 3.5 ≤ z ≤ 6.21. Fits are performed for the Stokes I and fractional polarization spectra, and Faraday rotation measures are derived using rotation measure synthesis and QU fitting. Using archival data of 476 polarized sources, we compare high-redshift (z > 3) source properties to a 15 GHz rest-frame luminosity matched sample of low-redshift (z < 3) sources to investigate if the polarization properties of radio sources at high redshifts are intrinsically different than those at low redshift. We find a mean of the rotation measure absolute values, corrected for Galactic rotation, of 50 ± 22 rad m-2 for z > 3 sources and 57 ± 4 rad m-2 for z < 3. Although there is some indication of lower intrinsic rotation measures at high-z possibly due to higher depolarization from the high-density environments, using several statistical tests we detect no significant difference between low- and high-redshift sources. Larger samples are necessary to determine any true physical difference.

Measurement-device-independent quantum key distribution with source state errors and statistical fluctuation

NASA Astrophysics Data System (ADS)

Jiang, Cong; Yu, Zong-Wen; Wang, Xiang-Bin

2017-03-01

We show how to calculate the secure final key rate in the four-intensity decoy-state measurement-device-independent quantum key distribution protocol with both source errors and statistical fluctuations with a certain failure probability. Our results rely only on the range of only a few parameters in the source state. All imperfections in this protocol have been taken into consideration without assuming any specific error patterns of the source.

Note: Temperature effects in the modified Howland current source for electrical bioimpedance spectroscopy.

PubMed

Fernandez Santos, S; Bertemes-Filho, P

2017-07-01

The aim of this study is to show how the modified Howland current source (MHCS) is affected by temperature changes. The source has been tested in a temperature range from 20 to 70 °C and frequency range from 100 Hz to 1 MHz. Parameters like output current, output impedance, total harmonic distortion, and oscillation have been measured. The measurements were made inside a temperature controlled environment. It was showed that the MHCS is stable at temperatures below 70 °C. Operational amplifiers with a low temperature drift and matching resistor should be carefully considered in order to prevent oscillations at high temperatures.

Note: Temperature effects in the modified Howland current source for electrical bioimpedance spectroscopy

NASA Astrophysics Data System (ADS)

Fernandez Santos, S.; Bertemes-Filho, P.

2017-07-01

The aim of this study is to show how the modified Howland current source (MHCS) is affected by temperature changes. The source has been tested in a temperature range from 20 to 70 °C and frequency range from 100 Hz to 1 MHz. Parameters like output current, output impedance, total harmonic distortion, and oscillation have been measured. The measurements were made inside a temperature controlled environment. It was showed that the MHCS is stable at temperatures below 70 °C. Operational amplifiers with a low temperature drift and matching resistor should be carefully considered in order to prevent oscillations at high temperatures.

Uncertainty quantification in fission cross section measurements at LANSCE

DOE PAGES

Tovesson, F.

2015-01-09

Neutron-induced fission cross sections have been measured for several isotopes of uranium and plutonium at the Los Alamos Neutron Science Center (LANSCE) over a wide range of incident neutron energies. The total uncertainties in these measurements are in the range 3–5% above 100 keV of incident neutron energy, which results from uncertainties in the target, neutron source, and detector system. The individual sources of uncertainties are assumed to be uncorrelated, however correlation in the cross section across neutron energy bins are considered. The quantification of the uncertainty contributions will be described here.

A differential absorption lidar instrument for the measurment of carbon dioxide and methane in the lower troposphere (Conference Presentation)

NASA Astrophysics Data System (ADS)

Budinov, Daniel; Clements, Robert; Rae, Cameron F.; Moncrieff, John B.; Jack, James W.

2016-12-01

Developments in the remote detection of trace gases in the atmosphere using Differential Absorption Lidar have been driven largely by improvements in two key technologies: lasers and detectors. We have designed and built a narrow linewidth pulsed laser source with a well-controlled output wavelength and sufficient pulse energy to measure the concentration profile of CO2 and CH4 to a range in excess of 4km. We describe here the initial measurements of concentration profiles recorded with this instrument. The system is built around a custom-designed Newtonian telescope with a 40cm diameter primary mirror. Laser sources and detectors attach directly to the side of the telescope allowing for flexible customization with a range of additional equipment. The instrument features an all-solid-state laser source based on an optical parametric oscillator (OPO) pumped by an YLF based diode-laser pumped solid-state laser and seeded by a tuned DFB seed. This provides a range of available wavelengths suitable for DIAL within the 1.5-1.6 μm spectral region. The output of the OPO is beam expanded and transmitted coaxially from the receiver telescope. A gas cell within the laser source controls the seed wavelength and allows the wavelength to be tuned to match a specific absorption feature of the selected gas species. The source can be rapidly tuned between the on-line and off-line wavelengths to make a DIAL measurement of either CO2 or CH4 The receiver is based on an InGaAs avalanche photodetector. Whilst photodiode detectors are a low-cost solution their limited sensitivity restricts the maximum range over which a signal can be detected. The receiver signal is digitised for subsequent processing to produce a sightline concentration profile. The instrument is mounted on a robust gimballed mount providing full directional movement within the upper hemisphere. Both static pointing and angular scan modes are available. Accurate angular position is available giving the sightline vector and supporting the interpretation of the concentration profile. Initial measurements have been made in the planetary boundary layer above the City of Edinburgh and these will be presented and discussed. Earlier measurements demonstrated that the signal from atmospheric scatter could be detected at ranges in excess of 6km. The later measurements have shown scatter signals at greater ranges, but with increasing noise at the longer ranges. This is expected as the signal decreases with the inverse of the range whereas the noise remains effectively constant. Range resolved concentration profiles for sightline vectors lying within an angular sector have been used to create a 3D map of concentration for that volume. This will be presented and discussed.

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.

Characterization of edge effects in precision low-coherence interferometry using broadband light sources

NASA Astrophysics Data System (ADS)

Taudt, Ch.; Baselt, T.; Nelsen, B.; Assmann, H.; Greiner, A.; Koch, E.; Hartmann, P.

2017-06-01

Within this work an alternative approach to precision surface profilometry based on a low-coherence interferometer is presented. Special emphasis is placed on the characterization of edge effects, which influence the measurement result on sharp edges and steep slopes. In contrast to other works, this examination focuses on the comparison of very broadband light sources such as a supercontinuum white-light source (SC; 380 - 1100 nm) and a laser-driven plasma light source (LDP; 200 - 1100 nm) and their influence on the formation of these effects. The interferometer is equipped with one of these broadband light sources and a defined dispersion over a given spectral range. The spectral width of the light sources in combination with the dispersive element defines the possible measurement range and resolution. Instead of detecting the signals only in a one-dimensional manner, an imaging spectrometer on the basis of a high resolution CMOS-camera is set-up. Through the introduction of a defined dispersion, a controlled phase variation in the spectral domain is created. This phase variation is dependent on the optical path difference between both arms and can therefore be used as a measure for the height of a structure which is present in one arm. The results of measurements on a 100 nm height standard with both selected light sources have been compared. Under consideration of the coherence length of both light sources of 1.58 μm for the SC source and 1.81 m for the LDP source differences could be recorded. Especially at sharp edges, the LDP light source could record height changes with slopes twice as steep as the SC source. Furthermore, it became obvious, that measurements with the SC source tend to show edge effects like batwings due to diffraction. Additional effects on the measured roughness and the flatness of the profile were investigated and discussed.

The Galway astronomical Stokes polarimeter: an all-Stokes optical polarimeter with ultra-high time resolution

NASA Astrophysics Data System (ADS)

Collins, Patrick; Kyne, Gillian; Lara, David; Redfern, Michael; Shearer, Andy; Sheehan, Brendan

2013-12-01

Many astronomical objects emit polarised light, which can give information both about their source mechanisms, and about (scattering) geometry in their source regions. To date (mostly) only the linearly polarised components of the emission have been observed in stellar sources. Observations have been constrained because of instrumental considerations to periods of excellent observing conditions, and to steady, slowly or periodically-varying sources. This leaves a whole range of interesting objects beyond the range of observation at present. The Galway Astronomical Stokes Polarimeter (GASP) has been developed to enable us to make observations on these very sources. GASP measures the four components of the Stokes Vector simultaneously over a broad wavelength range 400-800 nm., with a time resolution of order microseconds given suitable detectors and a bright source - this is possible because the optical design contains no moving or modulating components. The initial design of GASP is presented and we include some preliminary observational results demonstrating that components of the Stokes vector can be measured to % in conditions of poor atmospheric stability. Issues of efficiency and stability are addressed. An analysis of suitable astronomical targets, demanding the unique properties of GASP, is also presented.

Radiometric Spacecraft Tracking for Deep Space Navigation

NASA Technical Reports Server (NTRS)

Lanyi, Gabor E.; Border, James S.; Shin, Dong K.

2008-01-01

Interplanetary spacecraft navigation relies on three types of terrestrial tracking observables.1) Ranging measures the distance between the observing site and the probe. 2) The line-of-sight velocity of the probe is inferred from Doppler-shift by measuring the frequency shift of the received signal with respect to the unshifted frequency. 3) Differential angular coordinates of the probe with respect to natural radio sources are nominally obtained via a differential delay technique of (Delta) DOR (Delta Differential One-way Ranging). The accuracy of spacecraft coordinate determination depends on the measurement uncertainties associated with each of these three techniques. We evaluate the corresponding sources of error and present a detailed error budget.

Femtosecond soliton source with fast and broad spectral tunability.

PubMed

Masip, Martin E; Rieznik, A A; König, Pablo G; Grosz, Diego F; Bragas, Andrea V; Martinez, Oscar E

2009-03-15

We present a complete set of measurements and numerical simulations of a femtosecond soliton source with fast and broad spectral tunability and nearly constant pulse width and average power. Solitons generated in a photonic crystal fiber, at the low-power coupling regime, can be tuned in a broad range of wavelengths, from 850 to 1200 nm using the input power as the control parameter. These solitons keep almost constant time duration (approximately 40 fs) and spectral widths (approximately 20 nm) over the entire measured spectra regardless of input power. Our numerical simulations agree well with measurements and predict a wide working wavelength range and robustness to input parameters.

Magnetic properties of a new obsidian source, west Antelope Creek, Grant County, New Mexico

NASA Astrophysics Data System (ADS)

Sternberg, R. S.; Samuels, R.; Feinberg, J. M.; Shackley, M. S.

2013-12-01

This work is part of a Keck Geology Consortium project on characterizing obsidian sources in New Mexico using magnetic and geochemical properties. We collected over 3,000 samples, many of which were georeferenced, from 10 obsidian sources at three locales - Mule creek, Mt. Taylor, and Valles Caldera. One of the Mule Creek sources, herein called the west Antelope Creek (wAC) source, was previously unknown. The 143 samples collected at this source covered about 1 km2, but were not individually georeferenced. We plan to characterize the magnetic and chemical properties of this source to see if it is distinguishable from other nearby sources and useful for provenancing archaeological obsidians. Initial measurements on 34 specimens from 20 samples show NRM values range from 1-80 Am2/kg, and low-field susceptibilities range from 1.2-96 x 10-8 mass specific SI units. When there were two specimens from the same sample, results were in good agreement. The measurements define a rather broad field in NRM-susceptibility space compared to other Southwestern sources examined to date, and a considerably larger field than from the nearby Antelope Creek (AC) source. The previously measured NRM and susceptibility values from AC are all in the high end on both dimensions of the wAC field, so that these fields overlap but in many cases could be distinguished.

Estimation of the contributions of long range transported aerosol in East Asia to carbonaceous aerosol and PM concentrations in Seoul, Korea using highly time resolved measurements: a PSCF model approach.

PubMed

Jeong, Ukkyo; Kim, Jhoon; Lee, Hanlim; Jung, Jinsang; Kim, Young J; Song, Chul H; Koo, Ja-Ho

2011-07-01

The contributions of long range transported aerosol in East Asia to carbonaceous aerosol and particulate matter (PM) concentrations in Seoul, Korea were estimated with potential source contribution function (PSCF) calculations. Carbonaceous aerosol (organic carbon (OC) and elemental carbon (EC)), PM(2.5), and PM(10) concentrations were measured from April 2007 to March 2008 in Seoul, Korea. The PSCF and concentration weighted trajectory (CWT) receptor models were used to identify the spatial source distributions of OC, EC, PM(2.5), and coarse particles. Heavily industrialized areas in Northeast China such as Harbin and Changchun and East China including the Pearl River Delta region, the Yangtze River Delta region, and the Beijing-Tianjin region were identified as high OC, EC and PM(2.5) source areas. The conditional PSCF analysis was introduced so as to distinguish the influence of aerosol transported from heavily polluted source areas on a receptor site from that transported from relatively clean areas. The source contributions estimated using the conditional PSCF analysis account for not only the aerosol concentrations of long range transported aerosols but also the number of transport days effective on the measurement site. Based on the proposed algorithm, the condition of airmass pathways was classified into two types: one condition where airmass passed over the source region (PS) and another condition where airmass did not pass over the source region (NPS). For most of the seasons during the measurement period, 249.5-366.2% higher OC, EC, PM(2.5), and coarse particle concentrations were observed at the measurement site under PS conditions than under NPS conditions. Seasonal variations in the concentrations of OC, EC, PM(2.5), and coarse particles under PS, NPS, and background aerosol conditions were quantified. The contributions of long range transported aerosols on the OC, EC, PM(2.5), and coarse particle concentrations during several Asian dust events were also estimated. We also investigated the performance of the PSCF results obtained from combining highly time resolved measurement data and backward trajectory calculations via comparison with those from data in low resolutions. Reduced tailing effects and the larger coverage over the area of interest were observed in the PSCF results obtained from using the highly time resolved data and trajectories.

Improving frequencies range measurement of vibration sensor based on Fiber Bragg Grating (FBG)

NASA Astrophysics Data System (ADS)

Qomaruddin; Setiono, A.; Afandi, M. I.

2017-04-01

This research aimed to develop a vibration sensor based on Fiber Bragg Grating (FBG). The design was mainly done by attaching FBG at the cantilever. The free-end of the cantilever was tied to a vibration source in order to increase the measurement range of vibration frequencies. The results indicated that the developed sensor was capable of detecting wide range of frequencies (i.e. 10 - 1700 Hz). The results also showed both good stability and repeatability. The measured frequency range was 566 times greater than the range obtained from the previous works.

Broadband calibration of R/V Ewing seismic sources

NASA Astrophysics Data System (ADS)

Tolstoy, M.; Diebold, J. B.; Webb, S. C.; Bohnenstiehl, D. R.; Chapp, E.; Holmes, R. C.; Rawson, M.

2004-07-01

The effects of anthropogenic sound sources on marine mammals are of increasing interest and controversy [e.g., Malakoff, 2001]. To understand and mitigate better the possible impacts of specific sound sources, well-calibrated broadband measurements of acoustic received levels must be made in a variety of environments. In late spring 2003 an acoustic calibration study was conducted in the northern Gulf of Mexico to obtain broad frequency band measurements of seismic sources used by the R/V Maurice Ewing. Received levels in deep water were lower than anticipated based on modeling, and in shallow water they were higher. For the marine mammals of greatest concern (beaked whales) the 1-20 kHz frequency range is considered particularly significant [National Oceanic Atmospheric Administration and U. S. Navy, 2001; Frantzis et al., 2002]. 1/3-octave measurements show received levels at 1 kHz are ~20-33 dB (re: 1 μPa) lower than peak levels at 5-100 Hz, and decrease an additional ~20-33 dB in the 10-20 kHz range.

LED-based UV source for monitoring spectroradiometer properties

NASA Astrophysics Data System (ADS)

Sildoja, Meelis-Mait; Nevas, Saulius; Kouremeti, Natalia; Gröbner, Julian; Pape, Sven; Pendsa, Stefan; Sperfeld, Peter; Kemus, Fabian

2018-06-01

A compact and stable UV monitoring source based on state-of-the-art commercially available ultraviolet light emitting diodes (UV-LEDs) has been developed. It is designed to trace the radiometric stability—both responsivity and wavelength scale—of array spectroradiometers measuring direct solar irradiance in the wavelength range between 300 nm and 400 nm. The spectral irradiance stability of the UV-LED-based light source observed in the laboratory after seasoning (burning-in) the individual LEDs was better than 0.3% over a 12 h period of continuous operation. The integral irradiance measurements of the source over a period of several months, where the UV-LED source was not operated continuously between the measurements, showed stability within 0.3%. In-field measurements of the source with an array spectroradiometer indicated the stability of the source to be within the standard uncertainty of the spectroradiometer calibration, which was within 1% to 2%.

Atmospheric speciated mercury concentrations on an island between China and Korea: sources and transport pathways

NASA Astrophysics Data System (ADS)

Lee, G.-S.; Kim, P.-R.; Han, Y.-J.; Holsen, T. M.; Seo, Y.-S.; Yi, S.-M.

2015-11-01

As a global pollutant, mercury (Hg) is of particular concern in East Asia where anthropogenic emissions are the largest. In this study, speciated Hg concentrations were measured in the western most island in Korea, located between China and the Korean mainland to identify the importance of local, regional and distant Hg sources. Various tools including correlations with other pollutants, conditional probability function, and back-trajectory based analysis consistently indicated that Korean sources were important for gaseous oxidized mercury (GOM) whereas, for total gaseous mercury (TGM) and particulate bound mercury (PBM), long-range and regional transport were also important. A trajectory cluster based approach considering both Hg concentration and the fraction of time each cluster was impacting the site was developed to quantify the effect of Korean sources and out-of-Korean source. This analysis suggests that Korean sources contributed approximately 55 % of the GOM and PBM while there were approximately equal contributions from Korean and out-of-Korean sources for the TGM measured at the site. The ratio of GOM / PBM decreased when the site was impacted by long-range transport, suggesting that this ratio may be a useful tool for identifying the relative significance of local sources vs. long-range transport. The secondary formation of PBM through gas-particle partitioning with GOM was found to be important at low temperatures and high relative humidity.

Soliton microcomb range measurement

NASA Astrophysics Data System (ADS)

Suh, Myoung-Gyun; Vahala, Kerry J.

2018-02-01

Laser-based range measurement systems are important in many application areas, including autonomous vehicles, robotics, manufacturing, formation flying of satellites, and basic science. Coherent laser ranging systems using dual-frequency combs provide an unprecedented combination of long range, high precision, and fast update rate. We report dual-comb distance measurement using chip-based soliton microcombs. A single pump laser was used to generate dual-frequency combs within a single microresonator as counterpropagating solitons. We demonstrated time-of-flight measurement with 200-nanometer precision at an averaging time of 500 milliseconds within a range ambiguity of 16 millimeters. Measurements at distances up to 25 meters with much lower precision were also performed. Our chip-based source is an important step toward miniature dual-comb laser ranging systems that are suitable for photonic integration.

Evaluating measurements of carbon dioxide emissions using a precision source--A natural gas burner.

PubMed

Bryant, Rodney; Bundy, Matthew; Zong, Ruowen

2015-07-01

A natural gas burner has been used as a precise and accurate source for generating large quantities of carbon dioxide (CO2) to evaluate emissions measurements at near-industrial scale. Two methods for determining carbon dioxide emissions from stationary sources are considered here: predicting emissions based on fuel consumption measurements-predicted emissions measurements, and direct measurement of emissions quantities in the flue gas-direct emissions measurements. Uncertainty for the predicted emissions measurement was estimated at less than 1%. Uncertainty estimates for the direct emissions measurement of carbon dioxide were on the order of ±4%. The relative difference between the direct emissions measurements and the predicted emissions measurements was within the range of the measurement uncertainty, therefore demonstrating good agreement. The study demonstrates how independent methods are used to validate source emissions measurements, while also demonstrating how a fire research facility can be used as a precision test-bed to evaluate and improve carbon dioxide emissions measurements from stationary sources. Fossil-fuel-consuming stationary sources such as electric power plants and industrial facilities account for more than half of the CO2 emissions in the United States. Therefore, accurate emissions measurements from these sources are critical for evaluating efforts to reduce greenhouse gas emissions. This study demonstrates how a surrogate for a stationary source, a fire research facility, can be used to evaluate the accuracy of measurements of CO2 emissions.

Comparison of a new integrated current source with the modified Howland circuit for EIT applications.

PubMed

Hong, Hongwei; Rahal, Mohamad; Demosthenous, Andreas; Bayford, Richard H

2009-10-01

Multi-frequency electrical impedance tomography (MF-EIT) systems require current sources that are accurate over a wide frequency range (1 MHz) and with large load impedance variations. The most commonly employed current source design in EIT systems is the modified Howland circuit (MHC). The MHC requires tight matching of resistors to achieve high output impedance and may suffer from instability over a wide frequency range in an integrated solution. In this paper, we introduce a new integrated current source design in CMOS technology and compare its performance with the MHC. The new integrated design has advantages over the MHC in terms of power consumption and area. The output current and the output impedance of both circuits were determined through simulations and measurements over the frequency range of 10 kHz to 1 MHz. For frequencies up to 1 MHz, the measured maximum variation of the output current for the integrated current source is 0.8% whereas for the MHC the corresponding value is 1.5%. Although the integrated current source has an output impedance greater than 1 MOmega up to 1 MHz in simulations, in practice, the impedance is greater than 160 kOmega up to 1 MHz due to the presence of stray capacitance.

Characterization of modulated time-of-flight range image sensors

NASA Astrophysics Data System (ADS)

Payne, Andrew D.; Dorrington, Adrian A.; Cree, Michael J.; Carnegie, Dale A.

2009-01-01

A number of full field image sensors have been developed that are capable of simultaneously measuring intensity and distance (range) for every pixel in a given scene using an indirect time-of-flight measurement technique. A light source is intensity modulated at a frequency between 10-100 MHz, and an image sensor is modulated at the same frequency, synchronously sampling light reflected from objects in the scene (homodyne detection). The time of flight is manifested as a phase shift in the illumination modulation envelope, which can be determined from the sampled data simultaneously for each pixel in the scene. This paper presents a method of characterizing the high frequency modulation response of these image sensors, using a pico-second laser pulser. The characterization results allow the optimal operating parameters, such as the modulation frequency, to be identified in order to maximize the range measurement precision for a given sensor. A number of potential sources of error exist when using these sensors, including deficiencies in the modulation waveform shape, duty cycle, or phase, resulting in contamination of the resultant range data. From the characterization data these parameters can be identified and compensated for by modifying the sensor hardware or through post processing of the acquired range measurements.

A microchip laser source with stable intensity and frequency used for self-mixing interferometry.

PubMed

Zhang, Shaohui; Zhang, Shulian; Tan, Yidong; Sun, Liqun

2016-05-01

We present a stable 40 × 40 × 30 mm(3) Laser-diode (LD)-pumped-microchip laser (ML) laser source used for self-mixing interferometry which can measure non-cooperative targets. We simplify the coupling process of pump light in order to make its polarization and intensity robust against environmental disturbance. Thermal frequency stabilization technology is used to stabilize the laser frequency of both LD and ML. Frequency stability of about 1 × 10(-7) and short-term intensity fluctuation of 0.1% are achieved. The theoretical long-term displacement accuracy limited by frequency and intensity fluctuation is about 10 nm when the measuring range is 0.1 m. The line-width of this laser is about 25 kHz corresponding to 12 km coherent length and 6 km measurement range for self-mixing interference. The laser source has been equipped to a self-mixing interferometer, and it works very well.

CCN and IN concentration measurements during the Antarctic Circumnavigation Expedition

NASA Astrophysics Data System (ADS)

Stratmann, F.; Henning, S.; Löffler, M.; Welti, A.; Hartmann, M.; Wernli, H.; Baccarini, A.; Schmale, J.

2017-12-01

Cloud condensation nuclei (CCN) and ice nuclei (IN) concentrations measured during the Antarctic Circumnavigation Expedition (ACE) within the Study of Preindustrial-like Aerosol-Climate Effects (SPACE) are presented. The measurements give a circumpolar transect through the Sub Antarctic Ocean, where existing measurements are scarce. ACE took place during the austral summer 2016/17 and included exploration of different environments from pristine open Ocean to Antarctic islands and the southernmost ports of the 3 surrounding continents. CCN concentrations are measured over the entire range of expected in-cloud supersaturations from 0.1 to 1% using a CCNc instrument from DMT. IN concentrations are determined from filter samples at water saturated conditions from -5°C to -25°C, covering common temperatures of mixed-phase cloud glaciation. The sensitivity of measured IN and CCN concentrations to meteorological parameters, activity of marine biology and location is assessed to gain insight into potential sources of CCN and IN. Back trajectory modelling is used to allocate regional variations to aerosol sources originating in the marine boundary layer or long-range transport. The gained datasets constrain CCN and IN concentrations in the marine boundary layer along the cruise track. The comprehensive set of parallel measured parameters during ACE allow to evaluate contributions of local ocean-surface sources versus long-range transport to Sub-Antarctic CCN and IN. The measurements can be used as input to climate models, e.g. pristine Sub Antarctic conditions can provide an approximation for a pre-industrial environment.

Atmospheric CO2 measurements with a 2-μm DIAL instrument

NASA Astrophysics Data System (ADS)

Cadiou, Erwan; Dherbecourt*, Jean-Baptiste; Gorju, Guillaume; Melkonian, Jean-Michel; Godard, Antoine; Pelon, Jacques; Raybaut, Myriam

2018-04-01

We report on ground-based atmospheric concentration measurements of carbon dioxide, using a pulsed direct detection differential absorption lidar operating at 2051 nm. The transmitter is based on a tunable parametric source emitting 10-mJ energy, 10-ns duration Fourier-limited pulses. Range resolved concentration measurements have been carried out on the aerosol back-scattered signal. Cloud signals have been used to get long range integrated-path measurements.

Dark Energy Survey Year 1 Results: Cross-Correlation Redshifts in the DES -- Calibration of the Weak Lensing Source Redshift Distributions

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

Davis, C.; et al.

We present the calibration of the Dark Energy Survey Year 1 (DES Y1) weak lensing source galaxy redshift distributions from clustering measurements. By cross-correlating the positions of source galaxies with luminous red galaxies selected by the redMaGiC algorithm we measure the redshift distributions of the source galaxies as placed into different tomographic bins. These measurements constrain any such shifts to an accuracy ofmore » $$\\sim0.02$$ and can be computed even when the clustering measurements do not span the full redshift range. The highest-redshift source bin is not constrained by the clustering measurements because of the minimal redshift overlap with the redMaGiC galaxies. We compare our constraints with those obtained from $$\\texttt{COSMOS}$$ 30-band photometry and find that our two very different methods produce consistent constraints.« less

Measuring Seebeck Coefficient

NASA Technical Reports Server (NTRS)

Snyder, G. Jeffrey (Inventor)

2015-01-01

A high temperature Seebeck coefficient measurement apparatus and method with various features to minimize typical sources of errors is described. Common sources of temperature and voltage measurement errors which may impact accurate measurement are identified and reduced. Applying the identified principles, a high temperature Seebeck measurement apparatus and method employing a uniaxial, four-point geometry is described to operate from room temperature up to 1300K. These techniques for non-destructive Seebeck coefficient measurements are simple to operate, and are suitable for bulk samples with a broad range of physical types and shapes.

Mercury deposition in snow near an industrial emission source in the western U.S. and comparison to ISC3 model predictions

USGS Publications Warehouse

Abbott, M.L.; Susong, D.D.; Krabbenhoft, D.P.; Rood, A.S.

2002-01-01

Mercury (total and methyl) was evaluated in snow samples collected near a major mercury emission source on the Idaho National Engineering and Environmental Laboratory (INEEL) in southeastern Idaho and 160 km downwind in Teton Range in western Wyoming. The sampling was done to assess near-field (<12 km) deposition rates around the source, compare them to those measured in a relatively remote, pristine downwind location, and to use the measurements to develop improved, site-specific model input parameters for precipitation scavenging coefficient and the fraction of Hg emissions deposited locally. Measured snow water concentrations (ng L-1) were converted to deposition (ug m-2) using the sample location snow water equivalent. The deposition was then compared to that predicted using the ISC3 air dispersion/deposition model which was run with a range of particle and vapor scavenging coefficient input values. Accepted model statistical performance measures (fractional bias and normalized mean square error) were calculated for the different modeling runs, and the best model performance was selected. Measured concentrations close to the source (average = 5.3 ng L-1) were about twice those measured in the Teton Range (average = 2.7 ng L-1) which were within the expected range of values for remote background areas. For most of the sampling locations, the ISC3 model predicted within a factor of two of the observed deposition. The best modeling performance was obtained using a scavenging coefficient value for 0.25 ??m diameter particulate and the assumption that all of the mercury is reactive Hg(II) and subject to local deposition. A 0.1 ??m particle assumption provided conservative overprediction of the data, while a vapor assumption resulted in highly variable predictions. Partitioning a fraction of the Hg emissions to elemental Hg(0) (a U.S. EPA default assumption for combustion facility risk assessments) would have underpredicted the observed fallout.

The angular power spectrum measurement of the Galactic synchrotron emission using the TGSS survey

NASA Astrophysics Data System (ADS)

Choudhuri, Samir; Bharadwaj, Somnath; Ali, Sk. Saiyad; Roy, Nirupam; Intema, H. T.; Ghosh, Abhik

2018-05-01

Characterizing the diffuse Galactic synchrotron emission (DGSE) at arcminute angular scales is needed to remove this foregrounds in cosmological 21-cm measurements. Here, we present the angular power spectrum (Cl) measurement of the diffuse Galactic synchrotron emission using two fields observed by the TIFR GMRT Sky Survey (TGSS). We apply 2D Tapered Gridded Estimator (TGE) to estimate the Cl from the visibilities. We find that the residual data after subtracting the point sources is likely dominated by the diffuse Galactic synchrotron radiation across the angular multipole range 240 <= l <~ 500. We fit a power law to the measured Cl over this l range. We find that the slopes in both fields are consistent with earlier measurements. For the second field, however, we interpret the measured Cl as an upper limit for the DGSE as there is an indication of a significant residual point source contribution.

Method for measuring integrated sensitivity of solar cells and multielement photoconverters using an X-Y scanner

NASA Astrophysics Data System (ADS)

Naumov, V. V.; Grebenshchikov, O. A.; Zalesskii, V. B.

2006-09-01

We describe a method for automated measurement of the integrated sensitivity of solar cells (SCs) and multielement photoconverters (MPCs) using an experimental apparatus including a Pentium III personal computer (PC), an HP-34401A digital multimeter (DM), a stabilized radiation source (SRS), a controllable focusing system, an X-Y positioning device based on CD-RW optical disk storage devices. The method provides high accuracy in measuring the size of photosensitive areas of the solar cells and multielement photoconverters and inhomogeneities in their active regions, which makes it possible to correct the production process in the development stage and during fabrication of test prototypes for the solar cells and multielement photoconverters. The radiation power from the stabilized radiation source was ≤1 W; the ranges of the scanning steps along the X, Y coordinates were 10 100 µm, the range of the transverse cross sectional diameters of the focused radiation beam was 10 100 µm, the measurable photocurrents were 10-9 A to 2 A; scanning rate along the X, Y coordinates, ≤100 mm/sec; relative mean-square error (RMSE) for measurement of the integrated sensitivity of the solar cells, 0.2 ≤ γS int ≤ 0.9% in the ranges of measurable photocurrents 1 mA ≤ Iph ≤ 750 mA and areas 0.1 ≤ A ≤ 25 cm2 for number of measurements equal to ≤ 2· 105; instability of the radiation power (luminosity) ≤ 0.08% for 1 h or ≤ 0.4% for 8 h continuous operation; stabilized power range for the stabilized radiation source, 10-2 102 W. The software was written in Delphi 7.0.

Efficient measurement of large light source near-field color and luminance distributions for optical design and simulation

NASA Astrophysics Data System (ADS)

Kostal, Hubert; Kreysar, Douglas; Rykowski, Ronald

2009-08-01

The color and luminance distributions of large light sources are difficult to measure because of the size of the source and the physical space required for the measurement. We describe a method for the measurement of large light sources in a limited space that efficiently overcomes the physical limitations of traditional far-field measurement techniques. This method uses a calibrated, high dynamic range imaging colorimeter and a goniometric system to move the light source through an automated measurement sequence in the imaging colorimeter's field-of-view. The measurement is performed from within the near-field of the light source, enabling a compact measurement set-up. This method generates a detailed near-field color and luminance distribution model that can be directly converted to ray sets for optical design and that can be extrapolated to far-field distributions for illumination design. The measurements obtained show excellent correlation to traditional imaging colorimeter and photogoniometer measurement methods. The near-field goniometer approach that we describe is broadly applicable to general lighting systems, can be deployed in a compact laboratory space, and provides full near-field data for optical design and simulation.

Electron-density-sensitive Line Ratios of Fe XIII– XVI from Laboratory Sources Compared to CHIANTI

NASA Astrophysics Data System (ADS)

Weller, M. E.; Beiersdorfer, P.; Soukhanovskii, V. A.; Scotti, F.; LeBlanc, B. P.

2018-02-01

We present electron-density-sensitive line ratios for Fe XIII– XVI measured in the spectral wavelength range of 200–440 Å and an electron density range of (1–4) × 1013 cm‑3. The results provide a test at the high-density limit of density-sensitive line ratios useful for astrophysical studies. The measurements were performed on the National Spherical Torus Experiment-Upgrade, where electron densities were measured independently by the laser Thomson scattering diagnostic. Spectra were collected with a flat-field grazing-incidence spectrometer, which provided a spectral resolution of up to 0.3 Å, i.e., high resolution across the broad wavelength range. The response of the instrument was relatively calibrated using spectroscopic techniques in order to improve accuracy. The line ratios are compared to other laboratory sources and the latest version of CHIANTI (8.0.2), and an agreement within 30% is found.

Enhancing vibration measurements by Mössbauer effect

NASA Astrophysics Data System (ADS)

Pasquevich, G. A.; Veiga, A.; Zélis, P. Mendoza; Martínez, N.; van Raap, M. Fernández; Sánchez, F. H.

2014-01-01

The measurement of the Mössbauer effect in a system excited with a periodic perturbation can provide information about it. For that purpose, the Mössbauer absorption of a source-absorber set which hyperfine parameters are well known, is measured at a constant relative velocity (i.e. at a defined spectral energy). The resulting Mössbauer absorption periodic signal provides information of the sample ac perturbation response. This approach has been used time ago to measure small tympanic vibrations (mechanical perturbations). In this work we present an extension of the vibration experiments, by measuring them at various absorber-source relative velocities within a constant-velocity strategy. As a demonstration test, the frequency response of a piezoelectric diaphragm in the 100 Hz-5 kHz range is obtained with a custom electronic counter. The experiments are performed using a 57Co( Rh) source and a 25-m-thick stainless-steel absorber fixed to a piezoelectric diaphragm. Phase shifts and amplitude vibrations with velocities in the range from 1.5 m/s to 20 mm/s are well characterized, extending the linearity limit well beyond the earlier suggested one of 1 mm/s.

Acoustic characteristics of ultrasonic coded transmitters for fishery applications: could marine mammals hear them?

PubMed

Bowles, Ann E; Denes, Samuel L; Shane, Michael A

2010-11-01

Ultrasonic coded transmitters (UCTs) producing frequencies of 69-83 kHz are used increasingly to track fish and invertebrates in coastal and estuarine waters. To address concerns that they might be audible to marine mammals, acoustic properties of UCTs were measured off Mission Beach, San Diego, and at the U.S. Navy TRANSDEC facility. A regression model fitted to VEMCO UCT data yielded an estimated source level of 147 dB re 1 μPa SPL @ 1 m and spreading constant of 14.0. Based on TRANSDEC measurements, five VEMCO 69 kHz UCTs had source levels ranging from 146 to 149 dB re 1 μPa SPL @ 1 m. Five Sonotronics UCTs (69 kHz and 83 kHz) had source levels ranging from 129 to 137 dB re 1 μPa SPL @ 1 m. Transmitter directionality ranged from 3.9 to 18.2 dB. Based on propagation models and published data on marine mammal auditory psychophysics, harbor seals potentially could detect the VEMCO 69 kHz UCTs at ranges between 19 and >200 m, while odontocetes potentially could detect them at much greater ranges. California sea lions were not expected to detect any of the tested UCTs at useful ranges.

Determination of the mass of globular cluster X-ray sources

NASA Technical Reports Server (NTRS)

Grindlay, J. E.; Hertz, P.; Steiner, J. E.; Murray, S. S.; Lightman, A. P.

1984-01-01

The precise positions of the luminous X-ray sources in eight globular clusters have been measured with the Einstein X-Ray Observatory. When combined with similarly precise measurements of the dynamical centers and core radii of the globular clusters, the distribution of the X-ray source mass is determined to be in the range 0.9-1.9 solar mass. The X-ray source positions and the detailed optical studies indicate that (1) the sources are probably all of similar mass, (2) the gravitational potentials in these high-central density clusters are relatively smooth and isothermal, and (3) the X-ray sources are compact binaries and are probably formed by tidal capture.

Monte Carlo simulation of gamma-ray interactions in an over-square high-purity germanium detector for in-vivo measurements

NASA Astrophysics Data System (ADS)

Saizu, Mirela Angela

2016-09-01

The developments of high-purity germanium detectors match very well the requirements of the in-vivo human body measurements regarding the gamma energy ranges of the radionuclides intended to be measured, the shape of the extended radioactive sources, and the measurement geometries. The Whole Body Counter (WBC) from IFIN-HH is based on an “over-square” high-purity germanium detector (HPGe) to perform accurate measurements of the incorporated radionuclides emitting X and gamma rays in the energy range of 10 keV-1500 keV, under conditions of good shielding, suitable collimation, and calibration. As an alternative to the experimental efficiency calibration method consisting of using reference calibration sources with gamma energy lines that cover all the considered energy range, it is proposed to use the Monte Carlo method for the efficiency calibration of the WBC using the radiation transport code MCNP5. The HPGe detector was modelled and the gamma energy lines of 241Am, 57Co, 133Ba, 137Cs, 60Co, and 152Eu were simulated in order to obtain the virtual efficiency calibration curve of the WBC. The Monte Carlo method was validated by comparing the simulated results with the experimental measurements using point-like sources. For their optimum matching, the impact of the variation of the front dead layer thickness and of the detector photon absorbing layers materials on the HPGe detector efficiency was studied, and the detector’s model was refined. In order to perform the WBC efficiency calibration for realistic people monitoring, more numerical calculations were generated simulating extended sources of specific shape according to the standard man characteristics.

Sources and Fate of Chiral Organochlorine Pesticides in Western U.S. National Park Ecosystems

PubMed Central

Genualdi, Susan A.; Hageman, Kimberly J.; Ackerman, Luke K.; Usenko, Sascha; Simonich, Staci L. Massey

2011-01-01

The enantiomer fractions (EFs) of alpha-hexachlorocyclohexane (α-HCH), cis-, trans-, and oxychlordane, and heptachlor epoxide were measured in 73 snow, fish, and sediment samples collected from remote lake catchments, over a wide range of latitudes, in seven western U.S. National Parks/Preserves in order to investigate their sources, fate, accumulation and biotransformation in these ecosystems. The present study is novel because these lakes had no inflow or outflow and the measurement of chiral organochlorine pesticides (OCPs) EFs in snowpack from these lake catchments provided a better understanding of the OCP sources in the Western U.S., while their measurement in fish and sediment provided a better understanding of their biotic transformations within the lake catchments. Non-racemic α-HCH was measured in seasonal snowpack collected from continental U.S. National Parks, while racemic α-HCH was measured in seasonal snowpack collected from the Alaskan parks, suggesting the influence of regional sources to the continental U.S. parks and long-range sources to the Alaskan parks. The α-HCH EFs measured in trout collected from the lake catchments were similar to the α-HCH EFs measured in seasonal snowpack collected from the same lake catchments, suggesting that these fish did not biotransform α-HCH enantioselectively. Racemic cis-chlordane was measured in seasonal snowpack and sediment collected from Sequoia, indicating that it had not undergone significant enantioselective biotransformation in urban soils since its use as a termiticide in the surrounding urban areas. However, non-racemic cis-chlordane was measured in seasonal snowpack and sediments from Rocky Mountain, suggesting cis-chlordane does undergo enantioselective biotransformation in agricultural soils. The trout from these lakes showed preferential biotransformation of the (+)-enantiomer of cis-chlordane and the (−)-enantiomer of trans-chlordane. PMID:21462235

Measuring the Spectral Properties of Candidate Mineral Sources of the Venus Radar Anomalies

NASA Astrophysics Data System (ADS)

Kohler, E.; Maturilli, A.; Koulen, J.; Helbert, J.

2016-12-01

Radar mapping of the surface of Venus shows areas of high reflectivity (low emissivity) in the Venusian highlands at altitudes between 2.5-4.75 kilometers. The origin of the radar anomalies found in the highlands remains unclear. Previous experimental research investigated possible materials under simulated Venusian atmospheric and surface conditions, with special emphasis on the combined effect of pressure and temperature, and chemical composition. The results of these studies identified candidate source materials for the radar anomalies. In order to fully be considered a true source candidate the material must have spectroscopic measurements comparable to those measured on the surface of Venus where the high temperature affects spectral characteristics of minerals. The spectroscopic measurements of the previously identified candidate minerals were made at the Planetary Spectroscopy Laboratory (PSL) of DLR in Berlin in an effort to identify the anomaly source. The spectroscopic measurements were made with a FTIR Bruker Vertex 80V evacuated to .1 mbar and using several pairings of detector+beamsplitter to cover the spectral range from 0.2 to 20 µm. Each sample was poured in a stainless steel reflectance cup and measured fresh. Successively each cup was heated (via an induction system) in vacuum (0.07 mbar) at 400°C for 8 hours and measured again in the UV+VIS+MIR spectral range. Three consecutive cycles of heating and measuring reflectance were performed to account for spectral variations arising from the thermal processing of the samples. Heating the samples directly inside the reflectance cups allows to measure every time exactly the same surface, exposed to increasing levels of thermal processing. Results from this study are expected to further constrain the source of the Venus radar anomalies.

Volumetric Acoustic Vector Intensity Probe

NASA Technical Reports Server (NTRS)

Klos, Jacob

2006-01-01

A new measurement tool capable of imaging the acoustic intensity vector throughout a large volume is discussed. This tool consists of an array of fifty microphones that form a spherical surface of radius 0.2m. A simultaneous measurement of the pressure field across all the microphones provides time-domain near-field holograms. Near-field acoustical holography is used to convert the measured pressure into a volumetric vector intensity field as a function of frequency on a grid of points ranging from the center of the spherical surface to a radius of 0.4m. The volumetric intensity is displayed on three-dimensional plots that are used to locate noise sources outside the volume. There is no restriction on the type of noise source that can be studied. The sphere is mobile and can be moved from location to location to hunt for unidentified noise sources. An experiment inside a Boeing 757 aircraft in flight successfully tested the ability of the array to locate low-noise-excited sources on the fuselage. Reference transducers located on suspected noise source locations can also be used to increase the ability of this device to separate and identify multiple noise sources at a given frequency by using the theory of partial field decomposition. The frequency range of operation is 0 to 1400Hz. This device is ideal for the study of noise sources in commercial and military transportation vehicles in air, on land and underwater.

Acoustic centering of sources measured by surrounding spherical microphone arrays.

PubMed

Hagai, Ilan Ben; Pollow, Martin; Vorländer, Michael; Rafaely, Boaz

2011-10-01

The radiation patterns of acoustic sources have great significance in a wide range of applications, such as measuring the directivity of loudspeakers and investigating the radiation of musical instruments for auralization. Recently, surrounding spherical microphone arrays have been studied for sound field analysis, facilitating measurement of the pressure around a sphere and the computation of the spherical harmonics spectrum of the sound source. However, the sound radiation pattern may be affected by the location of the source inside the microphone array, which is an undesirable property when aiming to characterize source radiation in a unique manner. This paper presents a theoretical analysis of the spherical harmonics spectrum of spatially translated sources and defines four measures for the misalignment of the acoustic center of a radiating source. Optimization is used to promote optimal alignment based on the proposed measures and the errors caused by numerical and array-order limitations are investigated. This methodology is examined using both simulated and experimental data in order to investigate the performance and limitations of the different alignment methods. © 2011 Acoustical Society of America

Control Measure Dataset

EPA Pesticide Factsheets

The EPA Control Measure Dataset is a collection of documents describing air pollution control available to regulated facilities for the control and abatement of air pollution emissions from a range of regulated source types, whether directly through the use of technical measures, or indirectly through economic or other measures.

Fiber-coupled pillar array as a highly pure and stable single-photon source

NASA Astrophysics Data System (ADS)

Odashima, S.; Sasakura, H.; Nakajima, H.; Kumano, H.

2017-12-01

A highly pure and stable single-photon source is prepared that comprises a well-designed pillar array, in which each pillar contains only a few InAs quantum dots. A nano-pillar in this array is in direct contact with a fiber end surface and cooled in a liquid-He bath. Auto-correlation measurements show that this source provides an average g(2)(0) value of 0.0174 in the measured excitation-power range. This photon source and fiber coupling are quite rigid against external disturbances such as cooling-heating cycles and vibration, with long-term stability.

Low noise constant current source for bias dependent noise measurements

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

Talukdar, D.; Bose, Suvendu; Bardhan, K. K.

2011-01-15

A low noise constant current source used for measuring the 1/f noise in disordered systems in ohmic as well as nonohmic regime is described. The source can supply low noise constant current starting from as low as 1 {mu}A to a few tens of milliampere with a high voltage compliance limit of around 20 V. The constant current source has several stages, which can work in a standalone manner or together to supply the desired value of load current. The noise contributed by the current source is very low in the entire current range. The fabrication of a low noisemore » voltage preamplifier modified for bias dependent noise measurements and based on the existing design available in the MAT04 data sheet is also described.« less

Two methods for transmission line simulation model creation based on time domain measurements

NASA Astrophysics Data System (ADS)

Rinas, D.; Frei, S.

2011-07-01

The emission from transmission lines plays an important role in the electromagnetic compatibility of automotive electronic systems. In a frequency range below 200 MHz radiation from cables is often the dominant emission factor. In higher frequency ranges radiation from PCBs and their housing becomes more relevant. Main sources for this emission are the conducting traces. The established field measurement methods according CISPR 25 for evaluation of emissions suffer from the need to use large anechoic chambers. Furthermore measurement data can not be used for simulation model creation in order to compute the overall fields radiated from a car. In this paper a method to determine the far-fields and a simulation model of radiating transmission lines, esp. cable bundles and conducting traces on planar structures, is proposed. The method measures the electromagnetic near-field above the test object. Measurements are done in time domain in order to get phase information and to reduce measurement time. On the basis of near-field data equivalent source identification can be done. Considering correlations between sources along each conductive structure in model creation process, the model accuracy increases and computational costs can be reduced.

Sound Source Identification Through Flow Density Measurement and Correlation With Far Field Noise

NASA Technical Reports Server (NTRS)

Panda, J.; Seasholtz, R. G.

2001-01-01

Sound sources in the plumes of unheated round jets, in the Mach number range 0.6 to 1.8, were investigated experimentally using "casuality" approach, where air density fluctuations in the plumes were correlated with the far field noise. The air density was measured using a newly developed Molecular Rayleigh scattering based technique, which did not require any seeding. The reference at the end provides a detailed description of the measurement technique.

Soliton microcomb range measurement.

PubMed

Suh, Myoung-Gyun; Vahala, Kerry J

2018-02-23

Laser-based range measurement systems are important in many application areas, including autonomous vehicles, robotics, manufacturing, formation flying of satellites, and basic science. Coherent laser ranging systems using dual-frequency combs provide an unprecedented combination of long range, high precision, and fast update rate. We report dual-comb distance measurement using chip-based soliton microcombs. A single pump laser was used to generate dual-frequency combs within a single microresonator as counterpropagating solitons. We demonstrated time-of-flight measurement with 200-nanometer precision at an averaging time of 500 milliseconds within a range ambiguity of 16 millimeters. Measurements at distances up to 25 meters with much lower precision were also performed. Our chip-based source is an important step toward miniature dual-comb laser ranging systems that are suitable for photonic integration. Copyright © 2018 The Authors, some rights reserved; exclusive licensee American Association for the Advancement of Science. No claim to original U.S. Government Works.

Free-flying experiment to measure the Schawlow-Townes linewidth limit of a 300 THz laser oscillator

NASA Technical Reports Server (NTRS)

Byer, R. L.; Byvik, C. E.

1988-01-01

Recent advances in laser diode-pumped solid state laser sources permit the design and testing of laser sources with linewidths that approach the Schawlow-Townes limit of 1 Hz/mW of output power. Laser diode pumped solid state ring oscillators have been operated with CW output power levels of 25 mW at electrical efficiencies that exceed 6 percent. These oscillators are expected to operate for lifetimes that approach those of the laser diode sources which is now approaching 20,000 hours. The efficiency and lifetime of these narrow linewidth laser sources will enable space measurements of gravity waves, remote sensing applications (including local range rate and measurements), and laser sources for frequency and time standards. A free-flight experiment, 'SUNLITE', is being designed to measure the linewidth of this all-solid-state laser system.

Influence of regional biomass burning on the highly elevated organic carbon concentrations observed at Gosan, South Korea during a strong Asian dust period.

PubMed

Nguyen, Duc Luong; Kim, Jin Young; Ghim, Young Sung; Shim, Shang-Gyoo

2015-03-01

PM2.5 carbonaceous particles were measured at Gosan, South Korea during 29 March-11 April 2002 which includes a pollution period (30 March-01 April) when the highest concentrations of major anthropogenic species (nss-SO4 (2-), NO3 (-), and NH4 (+)) were observed and a strong Asian dust (AD) period (08-10 April) when the highest concentrations of mainly dust-originated trace elements (Al, Ca, Mg, and Fe) were seen. The concentrations of elemental carbon (EC) measured in the pollution period were higher than those measured in the strong AD period, whereas an inverse variation in the concentrations of organic carbon (OC) was observed. Based on the OC/EC ratios, the possible source that mainly contributed to the highly elevated OC concentrations measured in the strong AD period was biomass burning. The influence of the long-range transport of smoke plumes emitted from regional biomass burning sources was evaluated by using MODIS (Moderate Resolution Imaging Spectroradiometer) satellite data for fire locations and the potential source contribution function analysis. The most potential source regions of biomass burning were the Primorsky and Amur regions in Far Eastern Russia and southeastern and southwestern Siberia, Russia. Further discussion on the source characteristics suggested that the high OC concentrations measured in the strong AD period were significantly affected by the smoldering phase of biomass burning. In addition to biomass burning, secondary OC (SOC) formed during atmospheric long-range transport should be also considered as an important source of OC concentration measured at Gosan. Although this study dealt with the episodic case of the concurrent increase of dust and biomass burning particles, understanding the characteristics of heterogeneous mixing aerosol is essential in assessing the radiative forcing of aerosol.

Comparison of SANS instruments at reactors and pulsed sources

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

Thiyagarajan, P.; Epperson, J.E.; Crawford, R.K.

1992-09-01

Small angle neutron scattering is a general purpose technique to study long range fluctuations and hence has been applied in almost every field of science for material characterization. SANS instruments can be built at steady state reactors and at the pulsed neutron sources where time-of-flight (TOF) techniques are used. The steady state instruments usually give data over small q ranges and in order to cover a large q range these instruments have to be reconfigured several times and SANS measurements have to be made. These instruments have provided better resolution and higher data rates within their restricted q ranges untilmore » now, but the TOF instruments are now developing to comparable performance. The TOF-SANS instruments, by using a wide band of wavelengths, can cover a wide dynamic q range in a single measurement. This is a big advantage for studying systems that are changing and those which cannot be exactly reproduced. This paper compares the design concepts and performances of these two types of instruments.« less

Galactic water vapor emission: further observations of variability.

PubMed

Knowles, S H; Mayer, C H; Sullivan, W T; Cheung, A C

1969-10-10

Recent observations of the 1.35-centimeter line emission of water vapor from galactic sources show short-term variability in the spectra of several sources. Two additional sources, Cygnus 1 and NGC 6334N, have been observed, and the spectra of W49 and VY Canis Majoris were measured over a wider range of radial velocity.

A Robust Waveguide Millimeter-Wave Noise Source

NASA Technical Reports Server (NTRS)

Ehsan, Negar; Piepmeier, Jeffrey R.; Solly, Michael; Macmurphy, Shawn; Lucey, Jared; Wollack, Edward

2015-01-01

This paper presents the design, fabrication, and characterization of a millimeter-wave noise source for the 160- 210 GHz frequency range. The noise source has been implemented in an E-split-block waveguide package and the internal circuitry was developed on a quartz substrate. The measured excess noise ratio at 200 GHz is 9.6 dB.

Performance of the NIST goniocolorimeter with a broad-band source and multichannel charged coupled device based spectrometer.

PubMed

Podobedov, V B; Miller, C C; Nadal, M E

2012-09-01

The authors describe the NIST high-efficiency instrument for measurements of bidirectional reflectance distribution function of colored materials, including gonioapparent materials such as metallic and pearlescent coatings. The five-axis goniospectrometer measures the spectral reflectance of samples over a wide range of illumination and viewing angles. The implementation of a broad-band source and a multichannel CCD spectrometer corrected for stray light significantly increased the efficiency of the goniometer. In the extended range of 380 nm to 1050 nm, a reduction of measurement time from a few hours to a few minutes was obtained. Shorter measurement time reduces the load on the precise mechanical assembly ensuring high angular accuracy over time. We describe the application of matrix-based correction of stray light and the extension of effective dynamic range of measured fluxes to the values of 10(6) to 10(7) needed for the absolute characterization of samples. The measurement uncertainty was determined to be 0.7% (k = 2), which is comparable with similar instruments operating in a single channel configuration. Several examples of reflectance data obtained with the improved instrument indicate a 0.3% agreement compared to data collected with the single channel configuration.

Occurrence of perfluoroalkyl sulfonates and carboxylates in German drinking water sources compared to other countries.

PubMed

Lange, F T; Wenz, M; Schmidt, C K; Brauch, H-J

2007-01-01

Different homologues of C4 to C8 perfluoroalkyl carboxylates (PFCAs) and perfluoroalkyl sulfonates (PFASs) were detected in German surface waters, bank filtrates, artificially recharged groundwaters, and drinking waters. If no point sources are located nearby, the typically measured levels are in the low ng/L range. In the presence of point sources, such as a fluorochemical production site, a leaching agricultural fertilizer contaminated with PFCAs and PFASs, or drained PFC containing fire-fighting foams, much higher concentrations in the microg/L range occur. This situation is similar in Germany and other countries.

Direction-finding measurements of type 3 radio bursts out of the ecliptic plane

NASA Technical Reports Server (NTRS)

Baumback, M. M.; Kurth, W. S.; Gurnett, D. A.

1975-01-01

Direction-finding measurements with the plasma wave experiments on the HAWKEYE 1 and IMP 8 satellites are used to find the source locations of type 3 solar radio bursts in heliocentric latitude and longitude in a frequency range from 31.1 kHz to 500 kHz. Using an empirical model for the emission frequency as a function of radial distance from the sun the three-dimensional trajectory of the type 3 radio source can be determined from direction-finding measurements at different frequencies. Since the electrons which produce these radio emissions follow the magnetic field lines from the sun these measurements provide information on the three-dimensional structure of the magnetic field in the solar wind. The source locations projected into the ecliptic plane follow an Archimedian spiral. Perpendicular to the ecliptic plane the source locations usually follow a constant heliocentric latitude. With direction-finding measurements of this type it is also possible to determine the source size from the modulation factor of the received signals.

Magnetic characteristics of industrial dust from different sources of emission: A case study of Poland

NASA Astrophysics Data System (ADS)

Szuszkiewicz, Marcin; Magiera, Tadeusz; Kapička, Aleš; Petrovský, Eduard; Grison, Hanna; Gołuchowska, Beata

2015-05-01

Dust emission and deposition in topsoil have negative effect on individual components of the ecosystem. In addition to routine geochemical analyses, magnetic measurements may provide useful complementary information related to the type, concentration and grain-size distribution of the technogenic magnetic particles (TMPs) and thus the degree of contamination of the environment. The aim of this contribution is to use magnetic parameters in distinguishing dust from a wide range of sources of air pollution (power industry, cement, coke, ceramic industries and biomass combustion). We measured magnetic susceptibility, hysteresis parameters and thermomagnetic curves. Our results suggest that predominant component in tested samples is magnetite, only dust from coking plant and the combustion of lignite contained also maghemite and/or hematite. Mixture of sizes, ranging from fine single-domain to coarse multi-domain grains, was detected. Our results indicate that industrial dusts from various sources of emissions have different specific magnetic properties and magnetic measurements may provide very helpful information.

Precision improvement of frequency-modulated continuous-wave laser ranging system with two auxiliary interferometers

NASA Astrophysics Data System (ADS)

Shi, Guang; Wang, Wen; Zhang, Fumin

2018-03-01

The measurement precision of frequency-modulated continuous-wave (FMCW) laser distance measurement should be proportional to the scanning range of the tunable laser. However, the commercial external cavity diode laser (ECDL) is not an ideal tunable laser source in practical applications. Due to the unavoidable mode hopping and scanning nonlinearity of the ECDL, the measurement precision of FMCW laser distance measurements can be substantially affected. Therefore, an FMCW laser ranging system with two auxiliary interferometers is proposed in this paper. Moreover, to eliminate the effects of ECDL, the frequency-sampling method and mode hopping influence suppression method are employed. Compared with a fringe counting interferometer, this FMCW laser ranging system has a measuring error of ± 20 μm at the distance of 5.8 m.

SU-G-201-17: Verification of Dose Distributions From High-Dose-Rate Brachytherapy Ir-192 Source Using a Multiple-Array-Diode-Detector (MapCheck2)

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

Harpool, K; De La Fuente Herman, T; Ahmad, S

Purpose: To investigate quantitatively the accuracy of dose distributions for the Ir-192 high-dose-rate (HDR) brachytherapy source calculated by the Brachytherapy-Planning system (BPS) and measured using a multiple-array-diode-detector in a heterogeneous medium. Methods: A two-dimensional diode-array-detector system (MapCheck2) was scanned with a catheter and the CT-images were loaded into the Varian-Brachytherapy-Planning which uses TG-43-formalism for dose calculation. Treatment plans were calculated for different combinations of one dwell-position and varying irradiation times and different-dwell positions and fixed irradiation time with the source placed 12mm from the diode-array plane. The calculated dose distributions were compared to the measured doses with MapCheck2 delivered bymore » an Ir-192-source from a Nucletron-Microselectron-V2-remote-after-loader. The linearity of MapCheck2 was tested for a range of dwell-times (2–600 seconds). The angular effect was tested with 30 seconds irradiation delivered to the central-diode and then moving the source away in increments of 10mm. Results: Large differences were found between calculated and measured dose distributions. These differences are mainly due to absence of heterogeneity in the dose calculation and diode-artifacts in the measurements. The dose differences between measured and calculated due to heterogeneity ranged from 5%–12% depending on the position of the source relative to the diodes in MapCheck2 and different heterogeneities in the beam path. The linearity test of the diode-detector showed 3.98%, 2.61%, and 2.27% over-response at short irradiation times of 2, 5, and 10 seconds, respectively, and within 2% for 20 to 600 seconds (p-value=0.05) which depends strongly on MapCheck2 noise. The angular dependency was more pronounced at acute angles ranging up to 34% at 5.7 degrees. Conclusion: Large deviations between measured and calculated dose distributions for HDR-brachytherapy with Ir-192 may be improved when considering medium heterogeneity and dose-artifact of the diodes. This study demonstrates that multiple-array-diode-detectors provide practical and accurate dosimeter to verify doses delivered from the brachytherapy Ir-192-source.« less

Monolithically, widely tunable quantum cascade lasers based on a heterogeneous active region design.

PubMed

Zhou, Wenjia; Bandyopadhyay, Neelanjan; Wu, Donghai; McClintock, Ryan; Razeghi, Manijeh

2016-06-08

Quantum cascade lasers (QCLs) have become important laser sources for accessing the mid-infrared (mid-IR) spectral range, achieving watt-level continuous wave operation in a compact package at room temperature. However, up to now, wavelength tuning, which is desirable for most applications, has relied on external cavity feedback or exhibited a limited monolithic tuning range. Here we demonstrate a widely tunable QCL source over the 6.2 to 9.1 μm wavelength range with a single emitting aperture by integrating an eight-laser sampled grating distributed feedback laser array with an on-chip beam combiner. The laser gain medium is based on a five-core heterogeneous QCL wafer. A compact tunable laser system was built to drive the individual lasers within the array and produce any desired wavelength within the available spectral range. A rapid, broadband spectral measurement (520 cm(-1)) of methane using the tunable laser source shows excellent agreement to a measurement made using a standard low-speed infrared spectrometer. This monolithic, widely tunable laser technology is compact, with no moving parts, and will open new opportunities for MIR spectroscopy and chemical sensing.

Monolithically, widely tunable quantum cascade lasers based on a heterogeneous active region design

PubMed Central

Zhou, Wenjia; Bandyopadhyay, Neelanjan; Wu, Donghai; McClintock, Ryan; Razeghi, Manijeh

2016-01-01

Quantum cascade lasers (QCLs) have become important laser sources for accessing the mid-infrared (mid-IR) spectral range, achieving watt-level continuous wave operation in a compact package at room temperature. However, up to now, wavelength tuning, which is desirable for most applications, has relied on external cavity feedback or exhibited a limited monolithic tuning range. Here we demonstrate a widely tunable QCL source over the 6.2 to 9.1 μm wavelength range with a single emitting aperture by integrating an eight-laser sampled grating distributed feedback laser array with an on-chip beam combiner. The laser gain medium is based on a five-core heterogeneous QCL wafer. A compact tunable laser system was built to drive the individual lasers within the array and produce any desired wavelength within the available spectral range. A rapid, broadband spectral measurement (520 cm−1) of methane using the tunable laser source shows excellent agreement to a measurement made using a standard low-speed infrared spectrometer. This monolithic, widely tunable laser technology is compact, with no moving parts, and will open new opportunities for MIR spectroscopy and chemical sensing. PMID:27270634

SOURCE STRENGTHS OF ULTRAFINE AND FINE PARTICLES DUE TO COOKING WITH A GAS STOVE

EPA Science Inventory

Cooking, particularly frying, is an important source of particles indoors. Few studies have measured a full range of particle sizes, including ultrafine particles, produced during cooking. In this study, semicontinuous instruments with fine size discriminating ability were us...

General error analysis in the relationship between free thyroxine and thyrotropin and its clinical relevance.

PubMed

Goede, Simon L; Leow, Melvin Khee-Shing

2013-01-01

This treatise investigates error sources in measurements applicable to the hypothalamus-pituitary-thyroid (HPT) system of analysis for homeostatic set point computation. The hypothalamus-pituitary transfer characteristic (HP curve) describes the relationship between plasma free thyroxine [FT4] and thyrotropin [TSH]. We define the origin, types, causes, and effects of errors that are commonly encountered in TFT measurements and examine how we can interpret these to construct a reliable HP function for set point establishment. The error sources in the clinical measurement procedures are identified and analyzed in relation to the constructed HP model. The main sources of measurement and interpretation uncertainties are (1) diurnal variations in [TSH], (2) TFT measurement variations influenced by timing of thyroid medications, (3) error sensitivity in ranges of [TSH] and [FT4] (laboratory assay dependent), (4) rounding/truncation of decimals in [FT4] which in turn amplify curve fitting errors in the [TSH] domain in the lower [FT4] range, (5) memory effects (rate-independent hysteresis effect). When the main uncertainties in thyroid function tests (TFT) are identified and analyzed, we can find the most acceptable model space with which we can construct the best HP function and the related set point area.

Evaluation of Uncertainties in Measuring Particulate Matter Emission Factors from Atmospheric Fugitive Sources Using Optical Remote Sensing

NASA Astrophysics Data System (ADS)

Yuen, W.; Ma, Q.; Du, K.; Koloutsou-Vakakis, S.; Rood, M. J.

2015-12-01

Measurements of particulate matter (PM) emissions generated from fugitive sources are of interest in air pollution studies, since such emissions vary widely both spatially and temporally. This research focuses on determining the uncertainties in quantifying fugitive PM emission factors (EFs) generated from mobile vehicles using a vertical scanning micro-pulse lidar (MPL). The goal of this research is to identify the greatest sources of uncertainty of the applied lidar technique in determining fugitive PM EFs, and to recommend methods to reduce the uncertainties in this measurement. The MPL detects the PM plume generated by mobile fugitive sources that are carried downwind to the MPL's vertical scanning plane. Range-resolved MPL signals are measured, corrected, and converted to light extinction coefficients, through inversion of the lidar equation and calculation of the lidar ratio. In this research, both the near-end and far-end lidar equation inversion methods are considered. Range-resolved PM mass concentrations are then determined from the extinction coefficient measurements using the measured mass extinction efficiency (MEE) value, which is an intensive PM property. MEE is determined by collocated PM mass concentration and light extinction measurements, provided respectively by a DustTrak and an open-path laser transmissometer. These PM mass concentrations are then integrated with wind information, duration of plume event, and vehicle distance travelled to obtain fugitive PM EFs. To obtain the uncertainty of PM EFs, uncertainties in MPL signals, lidar ratio, MEE, and wind variation are considered. Error propagation method is applied to each of the above intermediate steps to aggregate uncertainty sources. Results include determination of uncertainties in each intermediate step, and comparison of uncertainties between the use of near-end and far-end lidar equation inversion methods.

First measurement of the VESUVIO neutron spectrum in the 30-80 MeV energy range using a Proton Recoil Telescope technique

NASA Astrophysics Data System (ADS)

Cazzaniga, C.; Tardocchi, M.; Croci, G.; Frost, C.; Giacomelli, L.; Grosso, G.; Hjalmarsson, A.; Rebai, M.; Rhodes, N. J.; Schooneveld, E. M.; Gorini, G.

2013-11-01

Measurements of the fast neutron energy spectrum at the ISIS spallation source are reported. The measurements were performed with a Proton Recoil Telescope consisting of a thin plastic foil placed in the neutron beam and two scintillator detectors. Results in the neutron energy range 30 MeV < En < 80 MeV are in good agreement with Monte Carlo simulations of the neutron spectrum.

Comparison of three rf plasma impedance monitors on a high phase angle planar inductively coupled plasma source

NASA Astrophysics Data System (ADS)

Uchiyama, H.; Watanabe, M.; Shaw, D. M.; Bahia, J. E.; Collins, G. J.

1999-10-01

Accurate measurement of plasma source impedance is important for verification of plasma circuit models, as well as for plasma process characterization and endpoint detection. Most impedance measurement techniques depend in some manner on the cosine of the phase angle to determine the impedance of the plasma load. Inductively coupled plasmas are generally highly inductive, with the phase angle between the applied rf voltage and the rf current in the range of 88 to near 90 degrees. A small measurement error in this phase angle range results in a large error in the calculated cosine of the angle, introducing large impedance measurement variations. In this work, we have compared the measured impedance of a planar inductively coupled plasma using three commercial plasma impedance monitors (ENI V/I probe, Advanced Energy RFZ60 and Advanced Energy Z-Scan). The plasma impedance is independently verified using a specially designed match network and a calibrated load, representing the plasma, to provide a measurement standard.

Electron-density-sensitive Line Ratios of Fe xiii– xvi from Laboratory Sources Compared to CHIANTI

DOE PAGES

Weller, M. E.; Beiersdorfer, P.; Soukhanovskii, V. A.; ...

2018-02-15

We present electron-density-sensitive line ratios for Fe xiii– xvi measured in the spectral wavelength range of 200–440 Å and an electron density range of (1-4) × 10 13 cm -3. The results provide a test at the high-density limit of density-sensitive line ratios useful for astrophysical studies. The measurements were performed on the National Spherical Torus Experiment-Upgrade, where electron densities were measured independently by the laser Thomson scattering diagnostic. Spectra were collected with a flat-field grazing-incidence spectrometer, which provided a spectral resolution of up to 0.3 Å, i.e., high resolution across the broad wavelength range. The response of the instrumentmore » was relatively calibrated using spectroscopic techniques in order to improve accuracy. Lastly, the line ratios are compared to other laboratory sources and the latest version of CHIANTI (8.0.2), and an agreement within 30% is found.« less

Electron-density-sensitive Line Ratios of Fe xiii– xvi from Laboratory Sources Compared to CHIANTI

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

Weller, M. E.; Beiersdorfer, P.; Soukhanovskii, V. A.

We present electron-density-sensitive line ratios for Fe xiii– xvi measured in the spectral wavelength range of 200–440 Å and an electron density range of (1-4) × 10 13 cm -3. The results provide a test at the high-density limit of density-sensitive line ratios useful for astrophysical studies. The measurements were performed on the National Spherical Torus Experiment-Upgrade, where electron densities were measured independently by the laser Thomson scattering diagnostic. Spectra were collected with a flat-field grazing-incidence spectrometer, which provided a spectral resolution of up to 0.3 Å, i.e., high resolution across the broad wavelength range. The response of the instrumentmore » was relatively calibrated using spectroscopic techniques in order to improve accuracy. Lastly, the line ratios are compared to other laboratory sources and the latest version of CHIANTI (8.0.2), and an agreement within 30% is found.« less

Evaluation of a lithium formate EPR dosimetry system for dose measurements around {sup 192}Ir brachytherapy sources

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

Antonovic, Laura; Gustafsson, Haakan; Alm Carlsson, Gudrun

2009-06-15

A dosimetry system using lithium formate monohydrate (HCO{sub 2}Li{center_dot}H{sub 2}O) as detector material and electron paramagnetic resonance (EPR) spectroscopy for readout has been used to measure absorbed dose distributions around clinical {sup 192}Ir sources. Cylindrical tablets with diameter of 4.5 mm, height of 4.8 mm, and density of 1.26 g/cm{sup 3} were manufactured. Homogeneity test and calibration of the dosimeters were performed in a 6 MV photon beam. {sup 192}Ir irradiations were performed in a PMMA phantom using two different source models, the GammaMed Plus HDR and the microSelectron PDR-v1 model. Measured absorbed doses to water in the PMMA phantommore » were converted to the corresponding absorbed doses to water in water phantoms of dimensions used by the treatment planning systems (TPSs) using correction factors explicitly derived for this experiment. Experimentally determined absorbed doses agreed with the absorbed doses to water calculated by the TPS to within {+-}2.9%. Relative standard uncertainties in the experimentally determined absorbed doses were estimated to be within the range of 1.7%-1.3% depending on the radial distance from the source, the type of source (HDR or PDR), and the particular absorbed doses used. This work shows that a lithium formate dosimetry system is well suited for measurements of absorbed dose to water around clinical HDR and PDR {sup 192}Ir sources. Being less energy dependent than the commonly used thermoluminescent lithium fluoride (LiF) dosimeters, lithium formate monohydrate dosimeters are well suited to measure absorbed doses in situations where the energy dependence cannot easily be accounted for such as in multiple-source irradiations to verify treatment plans. Their wide dynamic range and linear dose response over the dose interval of 0.2-1000 Gy make them suitable for measurements on sources of the strengths used in clinical applications. The dosimeter size needs, however, to be reduced for application to single-source dosimetry.« less

Database of Inlet and Exhaust Noise Shielding for Wedge-Shaped Airframe

NASA Technical Reports Server (NTRS)

Gerhold, Carl H.; Clark, Lorenzo R.

2001-01-01

An experiment to measure the noise shielding of the blended wing body design concept was developed using a simplified wedge-shaped airframe. The experimental study was conducted in the Langley Anechoic Noise Research Facility. A wideband, omnidirective sound source in a simulated engine nacelle was held at locations representative of a range of engine locations above the wing. The sound field around the model was measured with the airframe and source in place and with source alone, using an-array of microphones on a rotating hoop that is also translated along an axis parallel to the airframe axis. The insertion loss was determined from the difference between the two resulting contours. Although no attempt was made to simulate the noise characteristics of a particular engine, the broadband noise source radiated sound over a range of scaled frequencies encompassing 1 and 2 times the blade passage frequency representative of a large, high-bypass-ratio turbofan engine. The measured data show that significant shielding of the inlet-radiated noise is obtained in the area beneath and upstream of the model. The data show the sensitivity of insertion loss to engine location.

Methane Leak Detection and Emissions Quantification with UAVs

NASA Astrophysics Data System (ADS)

Barchyn, T.; Fox, T. A.; Hugenholtz, C.

2016-12-01

Robust leak detection and emissions quantification algorithms are required to accurately monitor greenhouse gas emissions. Unmanned aerial vehicles (UAVs, `drones') could both reduce the cost and increase the accuracy of monitoring programs. However, aspects of the platform create unique challenges. UAVs typically collect large volumes of data that are close to source (due to limited range) and often lower quality (due to weight restrictions on sensors). Here we discuss algorithm development for (i) finding sources of unknown position (`leak detection') and (ii) quantifying emissions from a source of known position. We use data from a simulated leak and field study in Alberta, Canada. First, we detail a method for localizing a leak of unknown spatial location using iterative fits against a forward Gaussian plume model. We explore sources of uncertainty, both inherent to the method and operational. Results suggest this method is primarily constrained by accurate wind direction data, distance downwind from source, and the non-Gaussian shape of close range plumes. Second, we examine sources of uncertainty in quantifying emissions with the mass balance method. Results suggest precision is constrained by flux plane interpolation errors and time offsets between spatially adjacent measurements. Drones can provide data closer to the ground than piloted aircraft, but large portions of the plume are still unquantified. Together, we find that despite larger volumes of data, working with close range plumes as measured with UAVs is inherently difficult. We describe future efforts to mitigate these challenges and work towards more robust benchmarking for application in industrial and regulatory settings.

Measurements of E-mode polarization and temperature-E-mode correlation in the cosmic microwave background from 100 square degrees of SPTPOL data

DOE PAGES

Crites, A. T.; Henning, J. W.; Ade, P. A. R.; ...

2015-05-18

Here, we present measurements ofmore » $E$-mode polarization and temperature-$E$$-mode correlation in the cosmic microwave background (CMB) using data from the first season of observations with SPTpol, the polarization-sensitive receiver currently installed on the South Pole Telescope (SPT). The observations used in this work cover 100~\\sqdeg\\ of sky with arcminute resolution at $$150\\,$GHz. We also report the $E$-mode angular auto-power spectrum ($EE$) and the temperature-$E$-mode angular cross-power spectrum ($TE$) over the multipole range $$500 < \\ell \\leq5000$$. These power spectra improve on previous measurements in the high-$$\\ell$$ (small-scale) regime. We fit the combination of the SPTpol power spectra, data from \\planck\\, and previous SPT measurements with a six-parameter \\LCDM cosmological model. Furthermore, we find that the best-fit parameters are consistent with previous results. The improvement in high-$$\\ell$$ sensitivity over previous measurements leads to a significant improvement in the limit on polarized point-source power: after masking sources brighter than 50\\,mJy in unpolarized flux at 150\\,GHz, we find a 95\\% confidence upper limit on unclustered point-source power in the $EE$ spectrum of $$D_\\ell = \\ell (\\ell+1) C_\\ell / 2 \\pi < 0.40 \\ \\mu{\\mbox{K}}^2$$ at $$\\ell=3000$$, indicating that future $EE$ measurements will not be limited by power from unclustered point sources in the multipole range $$\\ell < 3600$$, and possibly much higher in $$\\ell.$$« less

An Analysis of Fundamental Mode Surface Wave Amplitude Measurements

NASA Astrophysics Data System (ADS)

Schardong, L.; Ferreira, A. M.; van Heijst, H. J.; Ritsema, J.

2014-12-01

Seismic tomography is a powerful tool to decipher the Earth's interior structure at various scales. Traveltimes of seismic waves are widely used to build velocity models, whereas amplitudes are still only seldomly accounted for. This mainly results from our limited ability to separate the various physical effects responsible for observed amplitude variations, such as focussing/defocussing, scattering and source effects. We present new measurements from 50 global earthquakes of fundamental-mode Rayleigh and Love wave amplitude anomalies measured in the period range 35-275 seconds using two different schemes: (i) a standard time-domain amplitude power ratio technique; and (ii) a mode-branch stripping scheme. For minor-arc data, we observe amplitude anomalies with respect to PREM in the range of 0-4, for which the two measurement techniques show a very good overall agreement. We present here a statistical analysis and comparison of these datasets, as well as comparisons with theoretical calculations for a variety of 3-D Earth models. We assess the geographical coherency of the measurements, and investigate the impact of source, path and receiver effects on surface wave amplitudes, as well as their variations with frequency in a wider range than previously studied.

Real-time spectral characterization of a photon pair source using a chirped supercontinuum seed.

PubMed

Erskine, Jennifer; England, Duncan; Kupchak, Connor; Sussman, Benjamin

2018-02-15

Photon pair sources have wide ranging applications in a variety of quantum photonic experiments and protocols. Many of these protocols require well controlled spectral correlations between the two output photons. However, due to low cross-sections, measuring the joint spectral properties of photon pair sources has historically been a challenging and time-consuming task. Here, we present an approach for the real-time measurement of the joint spectral properties of a fiber-based four wave mixing source. We seed the four wave mixing process using a broadband chirped pulse, studying the stimulated process to extract information regarding the spontaneous process. In addition, we compare stimulated emission measurements with the spontaneous process to confirm the technique's validity. Joint spectral measurements have taken many hours historically and several minutes with recent techniques. Here, measurements have been demonstrated in 5-30 s depending on resolution, offering substantial improvement. Additional benefits of this approach include flexible resolution, large measurement bandwidth, and reduced experimental overhead.

Coherent Phonon Transport Measurement and Controlled Acoustic Excitations Using Tunable Acoustic Phonon Source in GHz-sub THz Range with Variable Bandwidth.

PubMed

Shen, Xiaohan; Lu, Zonghuan; Timalsina, Yukta P; Lu, Toh-Ming; Washington, Morris; Yamaguchi, Masashi

2018-05-04

We experimentally demonstrated a narrowband acoustic phonon source with simultaneous tunabilities of the centre frequency and the spectral bandwidth in the GHz-sub THz frequency range based on photoacoustic excitation using intensity-modulated optical pulses. The centre frequency and bandwidth are tunable from 65 to 381 GHz and 17 to 73 GHz, respectively. The dispersion of the sound velocity and the attenuation of acoustic phonons in silicon dioxide (SiO 2 ) and indium tin oxide (ITO) thin films were investigated using the acoustic phonon source. The sound velocities of SiO 2 and ITO films were frequency-independent in the measured frequency range. On the other hand, the phonon attenuations of both of SiO 2 and ITO films showed quadratic frequency dependences, and polycrystalline ITO showed several times larger attenuation than those in amorphous SiO 2 . In addition, the selective excitation of mechanical resonance modes was demonstrated in nanoscale tungsten (W) film using acoustic pulses with various centre frequencies and spectral widths.

Calibration of time of flight detectors using laser-driven neutron source

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

Mirfayzi, S. R.; Kar, S., E-mail: s.kar@qub.ac.uk; Ahmed, H.

2015-07-15

Calibration of three scintillators (EJ232Q, BC422Q, and EJ410) in a time-of-flight arrangement using a laser drive-neutron source is presented. The three plastic scintillator detectors were calibrated with gamma insensitive bubble detector spectrometers, which were absolutely calibrated over a wide range of neutron energies ranging from sub-MeV to 20 MeV. A typical set of data obtained simultaneously by the detectors is shown, measuring the neutron spectrum emitted from a petawatt laser irradiated thin foil.

Calibration of time of flight detectors using laser-driven neutron source.

PubMed

Mirfayzi, S R; Kar, S; Ahmed, H; Krygier, A G; Green, A; Alejo, A; Clarke, R; Freeman, R R; Fuchs, J; Jung, D; Kleinschmidt, A; Morrison, J T; Najmudin, Z; Nakamura, H; Norreys, P; Oliver, M; Roth, M; Vassura, L; Zepf, M; Borghesi, M

2015-07-01

Calibration of three scintillators (EJ232Q, BC422Q, and EJ410) in a time-of-flight arrangement using a laser drive-neutron source is presented. The three plastic scintillator detectors were calibrated with gamma insensitive bubble detector spectrometers, which were absolutely calibrated over a wide range of neutron energies ranging from sub-MeV to 20 MeV. A typical set of data obtained simultaneously by the detectors is shown, measuring the neutron spectrum emitted from a petawatt laser irradiated thin foil.

Calibration of time of flight detectors using laser-driven neutron source

NASA Astrophysics Data System (ADS)

Mirfayzi, S. R.; Kar, S.; Ahmed, H.; Krygier, A. G.; Green, A.; Alejo, A.; Clarke, R.; Freeman, R. R.; Fuchs, J.; Jung, D.; Kleinschmidt, A.; Morrison, J. T.; Najmudin, Z.; Nakamura, H.; Norreys, P.; Oliver, M.; Roth, M.; Vassura, L.; Zepf, M.; Borghesi, M.

2015-07-01

Calibration of three scintillators (EJ232Q, BC422Q, and EJ410) in a time-of-flight arrangement using a laser drive-neutron source is presented. The three plastic scintillator detectors were calibrated with gamma insensitive bubble detector spectrometers, which were absolutely calibrated over a wide range of neutron energies ranging from sub-MeV to 20 MeV. A typical set of data obtained simultaneously by the detectors is shown, measuring the neutron spectrum emitted from a petawatt laser irradiated thin foil.

Analysing seismic-source mechanisms by linear-programming methods.

USGS Publications Warehouse

Julian, B.R.

1986-01-01

Linear-programming methods are powerful and efficient tools for objectively analysing seismic focal mechanisms and are applicable to a wide range of problems, including tsunami warning and nuclear explosion identification. The source mechanism is represented as a point in the 6-D space of moment-tensor components. The present method can easily be extended to fit observed seismic-wave amplitudes (either signed or absolute) subject to polarity constraints, and to assess the range of mechanisms consistent with a set of measured amplitudes. -from Author

Sediment‐associated organic matter sources and sediment oxygen demand in a Special Area of Conservation (SAC): A case study of the River Axe, UK

PubMed Central

Zhang, Y.; McMillan, S.; Dixon, E. R.; Stringfellow, A.; Bateman, S.; Sear, D. A.

2017-01-01

Abstract Oxygen demand in river substrates providing important habitats for the early life stages of aquatic ecology, including lithophilous fish, can arise due to the oxidation of sediment‐associated organic matter. Oxygen depletion associated with this component of river biogeochemical cycling, will, in part, depend on the sources of such material. A reconnaissance survey was therefore undertaken to assess the relative contributions from bed sediment‐associated organic matter sources potentially impacting on the River Axe Special Area of Conservation (SAC), in SW England. Source fingerprinting, including Monte Carlo uncertainty analysis, suggested that the relative frequency‐weighted average median source contributions ranged between 19% (uncertainty range 0–82%) and 64% (uncertainty range 0–99%) for farmyard manures or slurries, 4% (uncertainty range 0–49%) and 35% (uncertainty range 0–100%) for damaged road verges, 2% (uncertainty range 0–100%) and 68% (uncertainty range 0–100%) for decaying instream vegetation, and 2% (full uncertainty range 0–15%) and 6% (uncertainty range 0–48%) for human septic waste. A reconnaissance survey of sediment oxygen demand (SOD) along the channel designated as a SAC yielded a mean SOD5 of 4 mg O2 g−1 dry sediment and a corresponding SOD20 of 7 mg O2 g−1 dry sediment, compared with respective ranges of 1–15 and 2–30 mg O2 g−1 dry sediment, measured by the authors for a range of river types across the UK. The findings of the reconnaissance survey were used in an agency (SW region) catchment appraisal exercise for informing targeted management to help protect the SAC. PMID:29527135

Model studies of laser absorption computed tomography for remote air pollution measurement

NASA Technical Reports Server (NTRS)

Wolfe, D. C., Jr.; Byer, R. L.

1982-01-01

Model studies of the potential of laser absorption-computed tomography are presented which demonstrate the possibility of sensitive remote atmospheric pollutant measurements, over kilometer-sized areas, with two-dimensional resolution, at modest laser source powers. An analysis of this tomographic reconstruction process as a function of measurement SNR, laser power, range, and system geometry, shows that the system is able to yield two-dimensional maps of pollutant concentrations at ranges and resolutions superior to those attainable with existing, direct-detection laser radars.

Radiation and Scattering Compact Antenna Laboratory (RASCAL) Capabilities Brochure

DTIC Science & Technology

2016-09-06

Array Measurements Integrated Measurement of Subsystems with Digital Backends RADIATION AND SCATTERING COMPACT ANTENNA LABORATORY...hardware gating to eliminate sources of error within the range itself. Processing is also available for multi-arm spiral antennas for the generation

An analysis of the readability characteristics of oral health information literature available to the public in Tasmania, Australia.

PubMed

Barnett, Tony; Hoang, Ha; Furlan, Ashlea

2016-03-17

The effectiveness of print-based health promotion materials is dependent on their readability. This study aimed to assess the characteristics of print-based oral health information literature publically available in Tasmania, Australia. Oral health education brochures were collected from 11 dental clinics across Tasmania and assessed for structure and format, content and readability. Reading level was calculated using three widely-used measures: Flesch-Kincaid Grade Level (FKGL), Flesch Reading Ease, and Simple Measure of Gobbledygook (SMOG) reading grade level. The FKGL of the 67 brochures sampled ranged from grade 3 to 13. The grade level for government health department brochures (n = 14) ranged from grade 4 to 11 (5.6 ± 1.8). Reading levels for materials produced by commercial sources (n = 22) ranged from 3 to 13 (8.3 ± 2.1), those from professional associations (n = 22) ranged from grade 7 to 11 (8.9 ± 0.9) and brochures produced by other sources (n = 9) ranged from 5 to 10 (7.6 ± 1.5). The SMOG test was positively correlated with the FKGL (rs = 0.92, p < 0.001) though consistently rated materials 2-3 grades higher. The reading level required to comprehend brochures published by government sources were, on average, lower than those from commercial, professional and other sources. Government materials were also more likely to contain fewer words and professional jargon terms than brochures from the other sources. A range of oral health information brochures were publically available for patients in both public and private dental clinics. However, their readability characteristics differed. Many brochures required a reading skill level higher than that suited to a large proportion of the Tasmanian population. Readability and other characteristics of oral health education materials should be assessed to ensure their suitability for use with patients, especially those suspected of having low literacy skills.

Experimental study of cluster formation in binary mixture of H2O and H2SO4 vapors in the presence of an ionizing radiation source

NASA Technical Reports Server (NTRS)

Singh, J. J.; Smith, A. C.; Yue, G. K.

1980-01-01

Molecular clusters formed in pure nitrogen containing H2O and H2SO4 vapors and exposed to a 3 mCi Ni63 beta source were studied in the mass range 50 to 780 amu using a quadrupole mass spectrometer. Measurements were made under several combinations of relative humidity and relative acidity ranging from 0.7 to 7.5 percent and 0.00047 to 0.06333 percent, respectively. The number of H2SO4 molecules in the clusters observed ranged from 1 to 7 whereas the number of H2O molecules ranged from 1 to 16. The experimental cluster spectra differ considerably from those calculated using the classical nucleation theory. First order calculations using modified surface tension values and including the effects of multipole moments of the nucleating molecules indicate that these effects may be enough to explain the difference between the measured and the calculated spectra.

Traceable calibration of ultraviolet meters used with broadband, extended sources.

PubMed

Coleman, A J; Collins, M; Saunders, J E

2000-01-01

A calibration system has been developed to provide increased accuracy in the measurement of the irradiance responsivity appropriate for UV meters used with broadband, extended sources of the type employed in phototherapy. The single wavelength responsivity of the test meter is obtained in the wavelength range 250-400 nm by intercomparison with a transfer standard meter in a narrow, monochromatic beam. Traceability to primary standard irradiance scales is provided via the National Measurement System with a best uncertainty of 7% (at 95% confidence). The effective responsivity of the test meter, when used with broadband extended sources, is calculated using the measured spectral and angular response of the meter and tabulated data on the spectral and spatial characteristics of the source radiance. The uncertainty in the effective responsivity, independent of the source variability, is estimated to be 10% (at 95% confidence). The advantages of this calibration system over existing approaches are discussed.

Directional Unfolded Source Term (DUST) for Compton Cameras.

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

Mitchell, Dean J.; Horne, Steven M.; O'Brien, Sean

2018-03-01

A Directional Unfolded Source Term (DUST) algorithm was developed to enable improved spectral analysis capabilities using data collected by Compton cameras. Achieving this objective required modification of the detector response function in the Gamma Detector Response and Analysis Software (GADRAS). Experimental data that were collected in support of this work include measurements of calibration sources at a range of separation distances and cylindrical depleted uranium castings.

Investigations of soft and hard tissues in oral cavity by spectral domain optical coherence tomography

NASA Astrophysics Data System (ADS)

Madjarova, Violeta Dimitrova; Yasuno, Yoshiaki; Makita, Shuichi; Hori, Yasuaki; Voeffray, Jean-Baptiste; Itoh, Masahide; Yatagai, Toyohiko; Tamura, Masami; Nanbu, Toshiyuki

2006-02-01

Fourier Domain Optical Coherence Tomography (SD-OCT) systems for dental measurements are demonstrated. Two systems have been developed. The first system is fiber based Michelson interferometer with super luminescent diodes at 1310 nm and 100 nm FWHM as a light source. The sensitivity of the system was 106 dB with depth measurement range in air of 2.5 mm. The second systems is a fiber based Mach-Zehnder interferometer with wavelength scanning laser as light source at center wavelength of 1310 nm, wavelength range of 110 nm and scanning rate of 20 KHz. The sensitivity of the system is 112 dB and depth measurement range in air is 6 mm. Both systems can acquire real-time three dimensional (3-D) images in the range of several second. The systems were applied for early caries detection in tooth, for diagnostics of tooth condition after operational tooth treatment, and for diagnostics of the alveolar bone structure. In-vivo measurements were performed on two volunteers. The systems were able to detect discontinuities in tooth and resin filling after tooth treatment. In addition early carries lesion was detected in one of the volunteers. The 3-D profile of the alveolar bone was acquired for first time with non-contact method.

Conceptual measurement framework for help-seeking for mental health problems

PubMed Central

Rickwood, Debra; Thomas, Kerry

2012-01-01

Background Despite a high level of research, policy, and practice interest in help-seeking for mental health problems and mental disorders, there is currently no agreed and commonly used definition or conceptual measurement framework for help-seeking. Methods A systematic review of research activity in the field was undertaken to investigate how help-seeking has been conceptualized and measured. Common elements were used to develop a proposed conceptual measurement framework. Results The database search revealed a very high level of research activity and confirmed that there is no commonly applied definition of help-seeking and no psychometrically sound measures that are routinely used. The most common element in the help-seeking research was a focus on formal help-seeking sources, rather than informal sources, although studies did not assess a consistent set of professional sources; rather, each study addressed an idiosyncratic range of sources of professional health and community care. Similarly, the studies considered help-seeking for a range of mental health problems and no consistent terminology was applied. The most common mental health problem investigated was depression, followed by use of generic terms, such as mental health problem, psychological distress, or emotional problem. Major gaps in the consistent measurement of help-seeking were identified. Conclusion It is evident that an agreed definition that supports the comparable measurement of help-seeking is lacking. Therefore, a conceptual measurement framework is proposed to fill this gap. The framework maintains that the essential elements for measurement are: the part of the help-seeking process to be investigated and respective time frame, the source and type of assistance, and the type of mental health concern. It is argued that adopting this framework will facilitate progress in the field by providing much needed conceptual consistency. Results will then be able to be compared across studies and population groups, and this will significantly benefit understanding of policy and practice initiatives aimed at improving access to and engagement with services for people with mental health concerns. PMID:23248576

A Compact 600 GHz Electronically Tunable Vector Measurement System for Submillimeter Wave Imaging

NASA Technical Reports Server (NTRS)

Dengler, Robert J.; Maiwald, Frank; Siegel, Peter H.

2006-01-01

A compact submillimeter wave transmission / reflection measurement system has been demonstrated at 560-635 GHz, with electronic tuning over the entire band. Maximum dynamic range measured at a single frequency is 90 dB (60 dB typical), and phase noise is less than +/- 2(deg). By using a frequency steerable lens at the source output and mixer input, the frequency agility of the system can be used to scan the source and receive beams, resulting in near real-time imaging capability using only a single pixel.

Day-night differences in the composition and sources of carbonaceous aerosol at a polluted regional background site in the Netherlands

NASA Astrophysics Data System (ADS)

Dusek, Ulrike; Broekema, Elise; Holzinger, Rupert; Röckmann, Thomas; Meijer, Harro

2017-04-01

The origin of carbonaceous aerosol differs during day- and night-time, because emissions from major sources such as traffic, biomass combustion, and secondary organic aerosol formation show a distinct diurnal pattern. Moreover, photochemical processing and evaporation of semi-volatile organic compounds are enhanced during day-time, due to the availability of sunlight and higher temperatures. Assessing day-night differences in sources and chemical composition can give an indication of the importance of local/regional carbon sources and processing, since day-night differences should be averaged out during long-range transport. If local sources dominate, one could expect a strong diurnal variation in the source profile, but if long-range transport dominates the diurnal variation would be much weaker. In this study we measure the isotopic (14C and 13C) and detailed chemical composition of the organic fraction of the aerosol on high volume PM2.5 filter samples that were collected separately during day and night time. Radiocarbon (14C) measurements are used to estimate three main aerosol sources of organic and elemental carbon (OC and EC): Fossil fuel combustion (ff), biomass combustion (bb), and biogenic sources (bio). The detailed chemical and stable isotopic composition are measured at different desorption temperatures from the filter, which separates the more and less refractory organic compounds. The composition of the organic aerosol is measured using an thermal-desporption Proton Transfer Reaction Time-of-Flight Mass Spectrometer (PTR-ToF-MS) method (Holzinger et al, 2010) and the stable isotopic composition is measured using a thermal desorption IRMS method (Dusek et al., 2013). Source apportionment results using 14C show that the contribution of fossil fuel combustion to EC and OC is higher during day-time than during night-time. This is valid for all seasons. During night-time biomass combustion plays a bigger role as a source of carbonaceous aerosol. Even in the summer, when biomass combustion is a small source, its relative contribution increases between 19:00 and 07:00. However, the diurnal changes in source contributions are relatively moderate (e.g., the biomass burning contribution to TC increased from 31% to 43% for the winter sample with the most distinct day-night difference.) This highlights the importance of long-range transport as a source of the carbonaceous aerosol in this region. First results from chemical composition measurements on four of the samples show that the concentration of less refractory organic carbon (desorption temperature up to 200 °C) increases at night-time much more strongly than the concentration of the more refractory carbon. Similarly, the concentration of small organic compounds with m/z < 100 also increases more strongly than heavier compounds. This indicates partitioning of semi-volatile OC as a possible additional night-time source. The chemical composition will be studied in more detail, focusing on diurnal changes in O/C ratios, individual compounds and compound classes, such as hydrocarbons or organic acids. Dusek, U., Meusinger, C., Oyama, B., Ramon, W., de Wilde, P., Holzinger, R., and Röckmann, T.: A thermal desorption system for measuring δ 13 C ratios on organic aerosol, Journal of aerosol science, 66, 72-82, 2013. Holzinger, R., Williams, J., Herrmann, F., Lelieveld, J., Donahue, N., Röckmann, T., 2010. Aerosol analysis using a Thermal-Desorption Proton-Transfer-Reaction Mass Spectrometer (TD-PTR-MS): a new approach to study processing of organic aerosols. Atmospheric chemistry and physics 10, 2257-2267.

Lidar stratospheric ozone measurements at the observatoire de Haute Provence (France)

NASA Technical Reports Server (NTRS)

Godin, S.; Pelon, J.; Megie, G.

1986-01-01

Strastospheric ozone monitoring is of particular importance to confirm present day theories predicting a maximal ozone depletion, due to chlorofluorocarbon emission, in the 35 to 45 km altitude range. Measurements presently rely on both ground based and satellite-borne passive experiments. Such systems have been recently shown to have intrinsic limitations mainly due to atmospheric aerosol presence and calibration problems. During the last few years, active lidar profiling of the ozone vertical distribution by the Differential Absorption Laser technique (DIAL) in the UV wavelength range has been developed using two different laser sources: a Nd-YAG pumped dye laser which enables a large tuning range of the UV emitted wavelengths; and exciplex laser sources using xenon chloride as an active medium and emitting at 308 nm, the off wavelength being usually generated by Raman shifting techniques. Advantages and limitations of using both of these systems are briefly discussed.

Noise pair velocity and range echo location system

DOEpatents

Erskine, D.J.

1999-02-16

An echo-location method for microwaves, sound and light capable of using incoherent and arbitrary waveforms of wide bandwidth to measure velocity and range (and target size) simultaneously to high resolution is disclosed. Two interferometers having very long and nearly equal delays are used in series with the target interposed. The delays can be longer than the target range of interest. The first interferometer imprints a partial coherence on an initially incoherent source which allows autocorrelation to be performed on the reflected signal to determine velocity. A coherent cross-correlation subsequent to the second interferometer with the source determines a velocity discriminated range. Dithering the second interferometer identifies portions of the cross-correlation belonging to a target apart from clutter moving at a different velocity. The velocity discrimination is insensitive to all slowly varying distortions in the signal path. Speckle in the image of target and antenna lobing due to parasitic reflections is minimal for an incoherent source. An arbitrary source which varies its spectrum dramatically and randomly from pulse to pulse creates a radar elusive to jamming. Monochromatic sources which jigger in frequency from pulse to pulse or combinations of monochromatic sources can simulate some benefits of incoherent broadband sources. Clutter which has a symmetrical velocity spectrum will self-cancel for short wavelengths, such as the apparent motion of ground surrounding target from a sidelooking airborne antenna. 46 figs.

Noise pair velocity and range echo location system

DOEpatents

Erskine, David J.

1999-01-01

An echo-location method for microwaves, sound and light capable of using incoherent and arbitrary waveforms of wide bandwidth to measure velocity and range (and target size) simultaneously to high resolution. Two interferometers having very long and nearly equal delays are used in series with the target interposed. The delays can be longer than the target range of interest. The first interferometer imprints a partial coherence on an initially incoherent source which allows autocorrelation to be performed on the reflected signal to determine velocity. A coherent cross-correlation subsequent to the second interferometer with the source determines a velocity discriminated range. Dithering the second interferometer identifies portions of the cross-correlation belonging to a target apart from clutter moving at a different velocity. The velocity discrimination is insensitive to all slowly varying distortions in the signal path. Speckle in the image of target and antenna lobing due to parasitic reflections is minimal for an incoherent source. An arbitrary source which varies its spectrum dramatically and randomly from pulse to pulse creates a radar elusive to jamming. Monochromatic sources which jigger in frequency from pulse to pulse or combinations of monochromatic sources can simulate some benefits of incoherent broadband sources. Clutter which has a symmetrical velocity spectrum will self-cancel for short wavelengths, such as the apparent motion of ground surrounding target from a sidelooking airborne antenna.

Understanding auditory distance estimation by humpback whales: a computational approach.

PubMed

Mercado, E; Green, S R; Schneider, J N

2008-02-01

Ranging, the ability to judge the distance to a sound source, depends on the presence of predictable patterns of attenuation. We measured long-range sound propagation in coastal waters to assess whether humpback whales might use frequency degradation cues to range singing whales. Two types of neural networks, a multi-layer and a single-layer perceptron, were trained to classify recorded sounds by distance traveled based on their frequency content. The multi-layer network successfully classified received sounds, demonstrating that the distorting effects of underwater propagation on frequency content provide sufficient cues to estimate source distance. Normalizing received sounds with respect to ambient noise levels increased the accuracy of distance estimates by single-layer perceptrons, indicating that familiarity with background noise can potentially improve a listening whale's ability to range. To assess whether frequency patterns predictive of source distance were likely to be perceived by whales, recordings were pre-processed using a computational model of the humpback whale's peripheral auditory system. Although signals processed with this model contained less information than the original recordings, neural networks trained with these physiologically based representations estimated source distance more accurately, suggesting that listening whales should be able to range singers using distance-dependent changes in frequency content.

Separating methane emissions from agricultural sources and natural gas: direct measurements of excess columns of CH4, C2H6 and NH3 in the Colorado Front Range

NASA Astrophysics Data System (ADS)

Kille, N.; Chiu, R.; Frey, M.; Hase, F.; Kumar Sha, M.; Blumenstock, T.; Hannigan, J. W.; Volkamer, R. M.

2017-12-01

Methane (CH4) is a major greenhouse gas emitted from biogenic, thermogenic, and pyrogenic sources. Here we demonstrate a novel approach to separate sources of CH4 emissions based on a network of small portable sensors performing column measurements in the Northern Colorado Front Range (NCFR). In the study area CH4 is emitted from biogenic sources such as concentrated animal feeding operations (CAFOs) and natural gas production and storage. In March 2015 we deployed a network of five Fourier Transform Spectrometers (FTS) to characterize the regional scale methane dome in Colorado's Denver-Julesburg Basin based on excess vertical column measurements (the column enhancement inside the dome over background). Three EM27sun FTS measured CH4, oxygen (O2) and water vapor (H2O) columns at Eaton, CO (inside the dome) and at two boundary sites; the CU mobile SOF (Solar Occultation Flux) measured ethane (C2H6), ammonia (NH3), and H2O at Eaton, CO. The column averaged dry air mole fractions XCH4, XC2H6, and XNH3 were determined using O2 columns for air mass factor normalization, and background column was subtracted to derive excess vertical columns of DXCH4, DXC2H6, DXNH3 at Eaton, CO. Eaton is located both near CAFOs and at the northern edge of oil and natural gas production wells. Our approach for source apportioning methane employs a linear regression analysis that explains DXCH4 in terms of DXC2H6 as tracer for natural gas sources, and DXNH3 as tracer for CAFO emissions. The results of the source apportionment are compared with literature values of the NH3/CH4 and C2H6/CH4 ratio to evaluate the method of excess columns, which is independent of boundary layer height.

Sources and Deposition of Polycyclic Aromatic Hydrocarbons to Western U.S. National Parks

PubMed Central

USENKO, SASCHA; MASSEY SIMONICH, STACI L.; HAGEMAN, KIMBERLY J.; SCHRLAU, JILL E.; GEISER, LINDA; CAMPBELL, DON H.; APPLEBY, PETER G.; LANDERS, DIXON H.

2010-01-01

Seasonal snowpack, lichens, and lake sediment cores were collected from fourteen lake catchments in eight western U.S. National Parks and analyzed for sixteen polycyclic aromatic hydrocarbons (PAHs) in order to determine their current and historical deposition, as well as to identify their potential sources. Seasonal snowpack was measured to determine the current wintertime atmospheric PAH deposition; lichens were measured to determine the long-term, year around deposition; and the temporal PAH deposition trends were reconstructed using lake sediment cores dated using 210Pb and 137Cs. The fourteen remote lake catchments ranged from low-latitude catchments (36.6° N) at high elevation (2900 masl) in Sequoia National Park, CA to high-latitude catchments (68.4° N) at low elevation (427 masl) in the Alaskan Arctic. Over 75% of the catchments demonstrated statistically significant temporal trends in ΣPAH sediment flux, depending on catchment proximity to source regions and topographic barriers. The ΣPAH concentrations and fluxes in seasonal snowpack, lichens, and surficial sediment were 3.6 to 60,000 times greater in the Snyder Lake catchment of Glacier National Park than the other 13 lake catchments. The PAH ratios measured in snow, lichen, and sediment were used to identify a local aluminum smelter as a major source of PAHs to the Snyder Lake catchment. These results suggest that topographic barriers influence the atmospheric transport and deposition of PAHs in high-elevation ecosystems and that PAH sources to these national park ecosystems range from local point sources to diffuse regional and global sources. PMID:20465303

Identification of source locations for atmospheric dry deposition of heavy metals during yellow-sand events in Seoul, Korea in 1998 using hybrid receptor models

NASA Astrophysics Data System (ADS)

Han, Young-Ji; Holsen, Thomas M.; Hopke, Philip K.; Cheong, Jang-Pyo; Kim, Ho; Yi, Seung-Muk

2004-10-01

Elemental dry deposition fluxes were measured using dry deposition plates from March to June 1998 in Seoul, Korea. During this spring sampling period several yellow-sand events characterized by long-range transport from China and Mongolia impacted the area. Understanding the impact of yellow-sand events on atmospheric dry deposition is critical to managing the heavy metal levels in the environment in Korea. In this study, the measured flux of a primarily crustal metal, Al and an anthropogenic metal, Pb was used with two hybrid receptor models, potential source contribution function (PSCF) and residence time weighted concentration (RTWC) for locating sources of heavy metals associated with atmospheric dry deposition fluxes during the yellow-sand events in Seoul, Korea. The PSCF using a criterion value of the 75th percentile of the measured dry deposition fluxes and RTWC results using the measured elemental dry deposition fluxes agreed well and consistently showed that there were large potential source areas in the Gobi Desert in China and Mongolia and industrial areas near Tianjin, Tangshan, and Shenyang in China. Major industrial areas of Shenyang, Fushun, and Anshan, the Central China loess plateau, the Gobi Desert, and the Alashan semi-desert in China were identified to be major source areas for the measured Pb flux in Seoul, Korea. For Al, the main industrial areas of Tangshan, Tianjin and Beijing, the Gobi Desert, the Alashan semi-desert, and the Central China loess plateau were found to be the major source areas. These results indicate that both anthropogenic sources such as industrial areas and natural sources such as deserts contribute to the high dry deposition fluxes of both Pb and Al in Seoul, Korea during yellow-sand events. RTWC resolved several high potential source areas. Modeling results indicated that the long-range transport of Al and Pb from China during yellow-sand events as well as non-yellow-sand spring daytimes increased atmospheric dry deposition of heavy metals in Korea.

Recent Advances in Source Localisation Using Range Measurements

DTIC Science & Technology

2015-10-01

Range Weighted SR- LS ............................................................................................ 5 GEOLOCATION USING SEMIDEFINITE... LS ) and the squared range least squares (SR- LS ) [3]. The R- LS -based formulation is of great interest and has been known for its optimal performance...to efficiently compute an R- LS position estimate. A number of optimization tools may be applied to globally solve the R- LS problem and are usually

On Road Study of Colorado Front Range Greenhouse Gases Distribution and Sources

NASA Astrophysics Data System (ADS)

Petron, G.; Hirsch, A.; Trainer, M. K.; Karion, A.; Kofler, J.; Sweeney, C.; Andrews, A.; Kolodzey, W.; Miller, B. R.; Miller, L.; Montzka, S. A.; Kitzis, D. R.; Patrick, L.; Frost, G. J.; Ryerson, T. B.; Robers, J. M.; Tans, P.

2008-12-01

The Global Monitoring Division and Chemical Sciences Division of the NOAA Earth System Research Laboratory have teamed up over the summer 2008 to experiment with a new measurement strategy to characterize greenhouse gases distribution and sources in the Colorado Front Range. Combining expertise in greenhouse gases measurements and in local to regional scales air quality study intensive campaigns, we have built the 'Hybrid Lab'. A continuous CO2 and CH4 cavity ring down spectroscopic analyzer (Picarro, Inc.), a CO gas-filter correlation instrument (Thermo Environmental, Inc.) and a continuous UV absorption ozone monitor (2B Technologies, Inc., model 202SC) have been installed securely onboard a 2006 Toyota Prius Hybrid vehicle with an inlet bringing in outside air from a few meters above the ground. To better characterize point and distributed sources, air samples were taken with a Portable Flask Package (PFP) for later multiple species analysis in the lab. A GPS unit hooked up to the ozone analyzer and another one installed on the PFP kept track of our location allowing us to map measured concentrations on the driving route using Google Earth. The Hybrid Lab went out for several drives in the vicinity of the NOAA Boulder Atmospheric Observatory (BAO) tall tower located in Erie, CO and covering areas from Boulder, Denver, Longmont, Fort Collins and Greeley. Enhancements in CO2, CO and destruction of ozone mainly reflect emissions from traffic. Methane enhancements however are clearly correlated with nearby point sources (landfill, feedlot, natural gas compressor ...) or with larger scale air masses advected from the NE Colorado, where oil and gas drilling operations are widespread. The multiple species analysis (hydrocarbons, CFCs, HFCs) of the air samples collected along the way bring insightful information about the methane sources at play. We will present results of the analysis and interpretation of the Hybrid Lab Front Range Study and conclude with perspectives on how we will adapt the measurement strategy to study CO2 anthropogenic emissions in Denver Basin.

Method and apparatus for making absolute range measurements

DOEpatents

Earl, Dennis D [Knoxville, TN; Allison, Stephen W [Knoxville, TN; Cates, Michael R [Oak Ridge, TN; Sanders, Alvin J [Knoxville, TN

2002-09-24

This invention relates to a method and apparatus for making absolute distance or ranging measurements using Fresnel diffraction. The invention employs a source of electromagnetic radiation having a known wavelength or wavelength distribution, which sends a beam of electromagnetic radiation through a screen at least partially opaque at the wavelength. The screen has an aperture sized so as to produce a Fresnel diffraction pattern. A portion of the beam travels through the aperture to a detector spaced some distance from the screen. The detector detects the central intensity of the beam as well as a set of intensities displaced from a center of the aperture. The distance from the source to the target can then be calculated based upon the known wavelength, aperture radius, and beam intensity.

Direct and quantitative broadband absorptance spectroscopy with multilayer cantilever probes

DOEpatents

Hsu, Wei-Chun; Tong, Jonathan Kien-Kwok; Liao, Bolin; Chen, Gang

2015-04-21

A system for measuring the absorption spectrum of a sample is provided that includes a broadband light source that produces broadband light defined within a range of an absorptance spectrum. An interferometer modulates the intensity of the broadband light source for a range of modulation frequencies. A bi-layer cantilever probe arm is thermally connected to a sample arm having at most two layers of materials. The broadband light modulated by the interferometer is directed towards the sample and absorbed by the sample and converted into heat, which causes a temperature rise and bending of the bi-layer cantilever probe arm. A detector mechanism measures and records the deflection of the probe arm so as to obtain the absorptance spectrum of the sample.

Broadband radiometric LED measurements

NASA Astrophysics Data System (ADS)

Eppeldauer, G. P.; Cooksey, C. C.; Yoon, H. W.; Hanssen, L. M.; Podobedov, V. B.; Vest, R. E.; Arp, U.; Miller, C. C.

2016-09-01

At present, broadband radiometric LED measurements with uniform and low-uncertainty results are not available. Currently, either complicated and expensive spectral radiometric measurements or broadband photometric LED measurements are used. The broadband photometric measurements are based on the CIE standardized V(λ) function, which cannot be used in the UV range and leads to large errors when blue or red LEDs are measured in its wings, where the realization is always poor. Reference irradiance meters with spectrally constant response and high-intensity LED irradiance sources were developed here to implement the previously suggested broadband radiometric LED measurement procedure [1, 2]. Using a detector with spectrally constant response, the broadband radiometric quantities of any LEDs or LED groups can be simply measured with low uncertainty without using any source standard. The spectral flatness of filtered-Si detectors and low-noise pyroelectric radiometers are compared. Examples are given for integrated irradiance measurement of UV and blue LED sources using the here introduced reference (standard) pyroelectric irradiance meters. For validation, the broadband measured integrated irradiance of several LED-365 sources were compared with the spectrally determined integrated irradiance derived from an FEL spectral irradiance lamp-standard. Integrated responsivity transfer from the reference irradiance meter to transfer standard and field UV irradiance meters is discussed.

High average power, highly brilliant laser-produced plasma source for soft X-ray spectroscopy.

PubMed

Mantouvalou, Ioanna; Witte, Katharina; Grötzsch, Daniel; Neitzel, Michael; Günther, Sabrina; Baumann, Jonas; Jung, Robert; Stiel, Holger; Kanngiesser, Birgit; Sandner, Wolfgang

2015-03-01

In this work, a novel laser-produced plasma source is presented which delivers pulsed broadband soft X-radiation in the range between 100 and 1200 eV. The source was designed in view of long operating hours, high stability, and cost effectiveness. It relies on a rotating and translating metal target and achieves high stability through an on-line monitoring device using a four quadrant extreme ultraviolet diode in a pinhole camera arrangement. The source can be operated with three different laser pulse durations and various target materials and is equipped with two beamlines for simultaneous experiments. Characterization measurements are presented with special emphasis on the source position and emission stability of the source. As a first application, a near edge X-ray absorption fine structure measurement on a thin polyimide foil shows the potential of the source for soft X-ray spectroscopy.

Evaluation of quality-control data collected by the U.S. Geological Survey for routine water-quality activities at the Idaho National Laboratory, Idaho, 1996–2001

USGS Publications Warehouse

Rattray, Gordon W.

2012-01-01

The U.S. Geological Survey, in cooperation with the U.S. Department of Energy, collects surface water and groundwater samples at and near the Idaho National Laboratory as part of a routine, site-wide, water-quality monitoring program. Quality-control samples are collected as part of the program to ensure and document the quality of environmental data. From 1996 to 2001, quality-control samples consisting of 204 replicates and 27 blanks were collected at sampling sites. Paired measurements from replicates were used to calculate variability (as reproducibility and reliability) from sample collection and analysis of radiochemical, chemical, and organic constituents. Measurements from field and equipment blanks were used to estimate the potential contamination bias of constituents. The reproducibility of measurements of constituents was calculated from paired measurements as the normalized absolute difference (NAD) or the relative standard deviation (RSD). The NADs and RSDs, as well as paired measurements with censored or estimated concentrations for which NADs and RSDs were not calculated, were compared to specified criteria to determine if the paired measurements had acceptable reproducibility. If the percentage of paired measurements with acceptable reproducibility for a constituent was greater than or equal to 90 percent, then the reproducibility for that constituent was considered acceptable. The percentage of paired measurements with acceptable reproducibility was greater than or equal to 90 percent for all constituents except orthophosphate (89 percent), zinc (80 percent), hexavalent chromium (53 percent), and total organic carbon (TOC; 38 percent). The low reproducibility for orthophosphate and zinc was attributed to calculation of RSDs for replicates with low concentrations of these constituents. The low reproducibility for hexavalent chromium and TOC was attributed to the inability to preserve hexavalent chromium in water samples and high variability with the analytical method for TOC. The reliability of measurements of constituents was estimated from pooled RSDs that were calculated for discrete concentration ranges for each constituent. Pooled RSDs of 15 to 33 percent were calculated for low concentrations of gross-beta radioactivity, strontium-90, ammonia, nitrite, orthophosphate, nickel, selenium, zinc, tetrachloroethene, and toluene. Lower pooled RSDs of 0 to 12 percent were calculated for all other concentration ranges of these constituents, and for all other constituents, except for one concentration range for gross-beta radioactivity, chloride, and nitrate + nitrite; two concentration ranges for hexavalent chromium; and TOC. Pooled RSDs for the 50 to 60 picocuries per liter concentration range of gross-beta radioactivity (reported as cesium-137) and the 10 to 60 milligrams per liter (mg/L) concentration range of nitrate + nitrite (reported as nitrogen [N]) were 17 percent. Chloride had a pooled RSD of 14 percent for the 20 to less than 60 mg/L concentration range. High pooled RSDs of 40 and 51 percent were calculated for two concentration ranges for hexavalent chromium and of 60 percent for TOC. Measurements from (1) field blanks were used to estimate the potential bias associated with environmental samples from sample collection and analysis, (2) equipment blanks were used to estimate the potential bias from cross contamination of samples collected from wells where portable sampling equipment was used, and (3) a source-solution blank was used to verify that the deionized water source-solution was free of the constituents of interest. If more than one measurement was available, the bias was estimated using order statistics and the binomial probability distribution. The source-solution blank had a detectable concentration of hexavalent chromium of 2 micrograms per liter. If this bias was from a source other than the source solution, then about 84 percent of the 117 hexavalent chromium measurements from environmental samples could have a bias of 10 percent or more. Of the 14 field blanks that were collected, only chloride (0.2 milligrams per liter) and ammonia (0.03 milligrams per liter as nitrogen), in one blank each, had detectable concentrations. With an estimated confidencelevel of 95 percent, at least 80 percent of the 1,987 chloride concentrations measured from all environmental samples had a potential bias of less than 8 percent. The ammonia bias, which may have occurred at the analytical laboratory, could produce a potential bias of 5-100 percent in eight potentially affected ammonia measurements. Of the 11 equipment blanks that were collected, chloride was detected in 4 of these blanks, sodium in 3 blanks, and sulfate and hexavalent chromium were each detected in 1 blank. The concentration of hexavalent chromium in the equipment blank was the same concentration as in the source-solution blank collected on the same day, which indicates that the hexavalent chromium in the equipment blank is probably from a source other than the portable sampling equipment, such as the sample bottles or the source-solution water itself. The potential bias for chloride, sodium, and sulfate measurements was estimated for environmental samples that were collected using portable sampling equipment. For chloride, it was estimated with 93 percent confidence that at least 80 percent of the measurements had a bias of less than 18 percent. For sodium and sulfate, it was estimated with 91 percent confidence that at least 70 percent of the measurements had a bias of less than 12 and 5 percent, respectively.

Atmospheric remote sensing of water vapor, HCl and CH4 using a continuously tunable Co:MgF2 laser

NASA Technical Reports Server (NTRS)

Menyuk, Norman; Killinger, Dennis K.

1987-01-01

A differential-absorption lidar system has been developed which uses a continuously tunable (1.5-2.3 micron) cobalt-doped magnesium fluoride laser as the radiation source. Preliminary atmospheric measurements of water vapor, HCl, and CH4 have been made with this system, including both path-averaged and ranged-resolved DIAL measurements at ranges up to 6 and 3 km, respectively.

Next Generation Air Measurements for Fugitive, Area Source, and Fence Line Applications

EPA Science Inventory

Next generation air measurements (NGAM) is an EPA term for the advancing field of air pollutant sensor technologies, data integration concepts, and geospatial modeling strategies. Ranging from personal sensors to satellite remote sensing, NGAM systems may provide revolutionary n...

Particulate trimethylamine in the summertime Canadian high Arctic lower troposphere

NASA Astrophysics Data System (ADS)

Köllner, Franziska; Schneider, Johannes; Willis, Megan D.; Klimach, Thomas; Helleis, Frank; Bozem, Heiko; Kunkel, Daniel; Hoor, Peter; Burkart, Julia; Leaitch, W. Richard; Aliabadi, Amir A.; Abbatt, Jonathan P. D.; Herber, Andreas B.; Borrmann, Stephan

2017-11-01

Size-resolved and vertical profile measurements of single particle chemical composition (sampling altitude range 50-3000 m) were conducted in July 2014 in the Canadian high Arctic during an aircraft-based measurement campaign (NETCARE 2014). We deployed the single particle laser ablation aerosol mass spectrometer ALABAMA (vacuum aerodynamic diameter range approximately 200-1000 nm) to identify different particle types and their mixing states. On the basis of the single particle analysis, we found that a significant fraction (23 %) of all analyzed particles (in total: 7412) contained trimethylamine (TMA). Two main pieces of evidence suggest that these TMA-containing particles originated from emissions within the Arctic boundary layer. First, the maximum fraction of particulate TMA occurred in the Arctic boundary layer. Second, compared to particles observed aloft, TMA particles were smaller and less oxidized. Further, air mass history analysis, associated wind data and comparison with measurements of methanesulfonic acid give evidence of a marine-biogenic influence on particulate TMA. Moreover, the external mixture of TMA-containing particles and sodium and chloride (Na / Cl-) containing particles, together with low wind speeds, suggests particulate TMA results from secondary conversion of precursor gases released by the ocean. In contrast to TMA-containing particles originating from inner-Arctic sources, particles with biomass burning markers (such as levoglucosan and potassium) showed a higher fraction at higher altitudes, indicating long-range transport as their source. Our measurements highlight the importance of natural, marine inner-Arctic sources for composition and growth of summertime Arctic aerosol.

Procedure for Separating Noise Sources in Measurements of Turbofan Engine Core Noise

NASA Technical Reports Server (NTRS)

Miles, Jeffrey Hilton

2006-01-01

The study of core noise from turbofan engines has become more important as noise from other sources like the fan and jet have been reduced. A multiple microphone and acoustic source modeling method to separate correlated and uncorrelated sources has been developed. The auto and cross spectrum in the frequency range below 1000 Hz is fitted with a noise propagation model based on a source couplet consisting of a single incoherent source with a single coherent source or a source triplet consisting of a single incoherent source with two coherent point sources. Examples are presented using data from a Pratt & Whitney PW4098 turbofan engine. The method works well.

Shearing interference microscope for step-height measurements.

PubMed

Trịnh, Hưng-Xuân; Lin, Shyh-Tsong; Chen, Liang-Chia; Yeh, Sheng-Lih; Chen, Chin-Sheng; Hoang, Hong-Hai

2017-05-01

A shearing interference microscope using a Savart prism as the shear plate is proposed for inspecting step-heights. Where the light beam propagates through the Savart prism and microscopic system to illuminate the sample, it then turns back to re-pass through the Savart prism and microscopic system to generate a shearing interference pattern on the camera. Two measurement modes, phase-shifting and phase-scanning, can be utilized to determine the depths of the step-heights on the sample. The first mode, which employs a narrowband source, is based on the five-step phase-shifting algorithm and has a measurement range of a quarter-wavelength. The second mode, which adopts a broadband source, is based on peak-intensity identification technology and has a measurement range up to a few micrometres. This paper is to introduce the configuration and measurement theory of this microscope, perform a setup used to implement it, and present the experimental results from the uses of the setup. The results not only verify the validity but also confirm the high measurement repeatability of the proposed microscope. © 2017 The Authors Journal of Microscopy © 2017 Royal Microscopical Society.

Tracking Oxidation During Transport of Trace Gases in Air from the Northern to Southern Hemisphere

NASA Astrophysics Data System (ADS)

Montzka, S. A.; Moore, F. L.; Atlas, E. L.; Parrish, D. D.; Miller, B. R.; Sweeney, C.; McKain, K.; Hall, B. D.; Siso, C.; Crotwell, M.; Hintsa, E. J.; Elkins, J. W.; Blake, D. R.; Barletta, B.; Meinardi, S.; Claxton, T.; Hossaini, R.

2017-12-01

Trace gas mole fractions contain the imprint of recent influences on an air mass such as sources, transport, and oxidation. Covariations among the many gases measured from flasks during ATom and HIPPO, and from the ongoing NOAA cooperative air sampling program enable recent influences to be identified from a wide range of sources including industrial activity, biomass burning, emissions from wetlands, and uptake by terrestrial ecosystems. In this work we explore the evolution of trace gas concentrations owing to atmospheric oxidation as air masses pass through the tropics, the atmospheric region with the highest concentrations of the hydroxyl radical. Variations in C2-C5 hydrocarbon concentrations downwind of source regions provide a measure of photochemical ageing in an air mass since emission, but they become less useful when tracking photochemical ageing as air is transported from the NH into the SH owing to their low mixing ratios, lifetimes that are very short relative to transport times, non-industrial sources in the tropics (e.g., biomass burning), and southern hemispheric sources. Instead, we consider a range of trace gases and trace gas pairs that provide a measure of photochemical processing as air transits the tropics. To be useful in this analysis, these trace gases would have lifetimes comparable to interhemispheric transport times, emissions arising from only the NH at constant relative magnitudes, and concentrations sufficient to allow precise and accurate measurements in both hemispheres. Some anthropogenically-emitted chlorinated hydrocarbons meet these requirements and have been measured during ATom, HIPPO, and from NOAA's ongoing surface sampling efforts. Consideration of these results and their implications for tracking photochemical processing in air as it is transported across the tropics will be presented.

Radiation force on absorbing targets and power measurements of a high intensity focused ultrasound (HIFU) source

NASA Astrophysics Data System (ADS)

Qian, Zuwen; Zhu, Zhemin; Ye, Shigong; Jiang, Wenhua; Zhu, Houqing; Yu, Jinshen

2010-10-01

Based on the analytic expressions for the radiated field of a circular concave piston given by Hasegawa et al., an integral for calculation of the radiation force on a plane absorbing target in a spherically focused field is derived. A general relation between acoustic power P and normal radiation force F n is obtained under the condition of kr ≫ 1. Numerical computation is carried out by using the symbolic computation program for practically focused sources and absorbing circular targets. The results show that, for a given source, there is a range of target positions where the radiation force is independent of the target’s position under the assumption that the contribution of the acoustic field behind the target to the radiation force can be neglected. The experiments are carried out and confirm that there is a range of target positions where the measured radiation force is basically independent of the target’s position even at high acoustic power (up to 700 W). It is believed that when the radiation force method is used to measure the acoustic power radiated from a focused source, the size of the target must be selected in such a way that no observable sound can be found in the region behind the target.

Sources of magnetic fields in recurrent interplanetary streams

NASA Technical Reports Server (NTRS)

Burlaga, L. F.; Behannon, K. W.; Hansen, S. F.; Pneuman, G. W.; Feldman, W. C.

1977-01-01

The sources of magnetic fields in recurrent streams were examined. Most fields and plasmas at 1 AU were related to coronal holes, and the magnetic field lines were open in those holes. Some of the magnetic fields and plasmas were related to open field line regions on the sun which were not associated with known coronal holes, indicating that open field lines are more basic than coronal holes as sources of the solar wind. Magnetic field intensities in five equatorial coronal holes ranged from 2G to 18G. Average measured photospheric magnetic fields along the footprints of the corresponding unipolar fields on circular equatorial arcs at 2.5 solar radii had a similar range and average, but in two cases the intensities were approximately three times higher than the projected intensities. The coronal footprints of the sector boundaries on the source surface at 2.5 solar radii, meandered between -45 deg and +45 deg latitude, and their inclination ranged from near zero to near ninety degrees.

Variations in AmLi source spectra and their estimation utilizing the 5 Ring Multiplicity Counter

NASA Astrophysics Data System (ADS)

Weinmann-Smith, R.; Beddingfield, D. H.; Enqvist, A.; Swinhoe, M. T.

2017-06-01

Active-mode assay systems are widely used for the safeguards of uranium items to verify compliance with the Non-Proliferation Treaty. Systems such as the Active-Well Coincidence Counter (AWCC) and the Uranium Neutron Coincidence Collar (UNCL) use americium-lithium (AmLi) neutron sources to induce fissions which are measured to determine the sample mass. These systems have historically relied on calibrations derived from well-defined standards. Recently, restricted access to standards or more difficult measurements have resulted in a reliance on modeling and simulation for the calibration of systems, which introduces potential simulation biases. The AmLi source energy spectra commonly used in the safeguards community do not accurately represent measurement results and the spectrum uncertainty can represent a large contribution to the total modeling uncertainty in active-mode systems. The 5-Ring Multiplicity Counter (5RMC) has been used to measure 17 AmLi sources. The measurements showed a significant spectral variation between different sources. Utilization of a spectrum that is specific to an individual source or a series of sources will give improved results over historical general spectra when modeling AmLi sources. Candidate AmLi neutron spectra were calculated in MCNP and SOURCES4C for a range of physical AmLi characteristics. The measurement and simulation data were used to fit reliable and accurate AmLi spectra for use in the simulation of active-mode systems. Spectra were created for average Gammatron C, Gammatron N, and MRC series sources, and for individual sources. The systematic uncertainty introduced by physical aspects of the AmLi source were characterized through simulations. The accuracy of spectra from the literature was compared.

Atmospheric boundary layer CO2 remote sensing with a direct detection LIDAR instrument based on a widely tunable optical parametric source.

PubMed

Cadiou, Erwan; Mammez, Dominique; Dherbecourt, Jean-Baptiste; Gorju, Guillaume; Pelon, Jacques; Melkonian, Jean-Michel; Godard, Antoine; Raybaut, Myriam

2017-10-15

We report on the capability of a direct detection differential absorption lidar (DIAL) for range resolved and integrated path (IPDIAL) remote sensing of CO 2 in the atmospheric boundary layer (ABL). The laser source is an amplified nested cavity optical parametric oscillator (NesCOPO) emitting approximately 8 mJ at the two measurement wavelengths selected near 2050 nm. Direct detection atmospheric measurements are taken from the ground using a 30 Hz frequency switching between emitted wavelengths. Results show that comparable precision measurements are achieved in DIAL and IPDIAL modes (not better than a few ppm) on high SNR targets such as near range ABL aerosol and clouds, respectively. Instrumental limitations are analyzed and degradation due to cloud scattering variability is discussed to explain observed DIAL and IPDIAL limitations.

Hard X-ray dosimetry of a plasma focus suitable for industrial radiography

NASA Astrophysics Data System (ADS)

Knoblauch, P.; Raspa, V.; Di Lorenzo, F.; Clausse, A.; Moreno, C.

2018-04-01

Dosimetric measurements of the hard X-ray emission by a small-chamber 4.7 kJ Mather-type plasma focus device capable of producing neat radiographs of metallic objects, were carried out with a set of thermoluminescent detectors TLD 700 (LiF:Mg,Ti). Measurements of the hard X-ray dose dependence with the angular position relative to the electrodes axis, are presented. The source-detector distance was changed in the range from 50 to 100 cm, and the angular positions were explored between ± 70°, relative to the symmetry axis of the electrodes. On-axis measurements show that the X-ray intensity is uniform within a half aperture angle of 6°, in which the source delivers an average dose of (1.5 ± 0.1) mGy/sr per shot. Monte Carlo calculations suggest that the energy of the electron beam responsible for the X-ray emission ranges 100-600 keV.

Operational and theoretical temperature considerations in a Penning surface plasma source

NASA Astrophysics Data System (ADS)

Faircloth, D. C.; Lawrie, S. R.; Pereira Da Costa, H.; Dudnikov, V.

2015-04-01

A fully detailed 3D thermal model of the ISIS Penning surface plasma source is developed in ANSYS. The proportion of discharge power applied to the anode and cathode is varied until the simulation matches the operational temperature observations. The range of possible thermal contact resistances are modelled, which gives an estimation that between 67% and 85% of the discharge power goes to the cathode. Transient models show the electrode surface temperature rise during the discharge pulse for a range of duty cycles. The implications of these measurements are discussed and a mechanism for governing cesium coverage proposed. The requirements for the design of a high current long pulse source are stated.

Vehicular sources in acoustic propagation experiments

NASA Technical Reports Server (NTRS)

Prado, Gervasio; Fitzgerald, James; Arruda, Anthony; Parides, George

1990-01-01

One of the most important uses of acoustic propagation models lies in the area of detection and tracking of vehicles. Propagation models are used to compute transmission losses in performance prediction models and to analyze the results of past experiments. Vehicles can also provide the means for cost effective experiments to measure acoustic propagation conditions over significant ranges. In order to properly correlate the information provided by the experimental data and the propagation models, the following issues must be taken into consideration: the phenomenology of the vehicle noise sources must be understood and characterized; the vehicle's location or 'ground truth' must be accurately reproduced and synchronized with the acoustic data; and sufficient meteorological data must be collected to support the requirements of the propagation models. The experimental procedures and instrumentation needed to carry out propagation experiments are discussed. Illustrative results are presented for two cases. First, a helicopter was used to measure propagation losses at a range of 1 to 10 Km. Second, a heavy diesel-powered vehicle was used to measure propagation losses in the 300 to 2200 m range.

Vehicular sources in acoustic propagation experiments

NASA Astrophysics Data System (ADS)

Prado, Gervasio; Fitzgerald, James; Arruda, Anthony; Parides, George

1990-12-01

One of the most important uses of acoustic propagation models lies in the area of detection and tracking of vehicles. Propagation models are used to compute transmission losses in performance prediction models and to analyze the results of past experiments. Vehicles can also provide the means for cost effective experiments to measure acoustic propagation conditions over significant ranges. In order to properly correlate the information provided by the experimental data and the propagation models, the following issues must be taken into consideration: the phenomenology of the vehicle noise sources must be understood and characterized; the vehicle's location or 'ground truth' must be accurately reproduced and synchronized with the acoustic data; and sufficient meteorological data must be collected to support the requirements of the propagation models. The experimental procedures and instrumentation needed to carry out propagation experiments are discussed. Illustrative results are presented for two cases. First, a helicopter was used to measure propagation losses at a range of 1 to 10 Km. Second, a heavy diesel-powered vehicle was used to measure propagation losses in the 300 to 2200 m range.

Determination of the optimum-size californium-252 neutron source for borehole capture gamma-ray analysis

USGS Publications Warehouse

Senftle, F.E.; Macy, R.J.; Mikesell, J.L.

1979-01-01

The fast- and thermal-neutron fluence rates from a 3.7 ??g 252Cf neutron source in a simulated borehole have been measured as a function of the source-to-detector distance using air, water, coal, iron ore-concrete mix, and dry sand as borehole media. Gamma-ray intensity measurements were made for specific spectral lines at low and high energies for the same range of source-to-detector distances in the iron ore-concrete mix and in coal. Integral gamma-ray counts across the entire spectrum were also made at each source-to-detector distance. From these data, the specific neutron-damage rate, and the critical count-rate criteria, we show that in an iron ore-concrete mix (low hydrogen concentration), 252Cf neutron sources of 2-40 ??g are suitable. The source size required for optimum gamma-ray sensitivity depends on the energy of the gamma ray being measured. In a hydrogeneous medium such as coal, similar measurements were made. The results show that sources from 2 to 20 ??g are suitable to obtain the highest gamma-ray sensitivity, again depending on the energy of the gamma ray being measured. In a hydrogeneous medium, significant improvement in sensitivity can be achieved by using faster electronics; in iron ore, it cannot. ?? 1979 North-Holland Publishing Co.

Upgrades to the Closed Bomb Facility and Measurement of Propellant Burning Rate

DTIC Science & Technology

2010-01-01

attenuation ratio myScope.WriteString (":CHAN1:RANGe " + CStr (Me.tbVRange.value)) ‘Sets the vertical voltage range myScope.WriteString (":CHAN1...OFFSet " + CStr (Me.tboffset.value)) ‘Sets the voltage offset myScope.WriteString ":CHAN1:PROB:STYP SING" ‘Sets the signal type...myScope.WriteString (":TRIG:EDGE:SOURce CHAN" + CStr (Int(val(GetRegistry(CollType, cCHANNEL))))) ‘Sets the source channel myScope.WriteString

MO-F-CAMPUS-T-04: Utilization of Optical Dosimeter for Modulated Spot-Scanning Particle Beam

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

Hsi, W; Li, Y; Huang, Z

Purpose: To present the utilization of an optical dosimeter for modulated spot-scanning carbon-ion and proton beams during the acceptance test of Siemens IONTRIS system. Method and Materials: An optical dosimeter using phosphor scintillation was developed to map and interactively analyze the shapes and sizes of spots over 190 energies for ProTom modulated-scanning system. The dose response to proton had been characterized with proper pixel calibration at ProTom system. The dose response was further studied at 0.7 cm depths by uniform 8cm in-diameter fields of 424.89 MeV/u (E290) carbon-ions and 215.18MeV (E282) protons at IONTRIS system. The virtual source axial distancesmore » (vSAD) of carbonions and protons of IONTRIS system was investigated by measuring either variations of spot position or field size at five different locations to Isocenter. By measuring lateral profiles of uniform doses with varied thin-thicknesses of chest-board pattern and placing the scintillation plate at near to the distal edge, range variations at different off-axis-distances (rOAD) were examined. Relative accuracy and reproducibility of beam range were measured for three beam ranges with a ramping block at front of scintillation plate. Results: Similar dose response was observed for high energies of carbon ions and protons. Mean vSAD at X and Y axes were 744.1 cm and 807.4cm with deviation of 7.4cm and 7.7cm, respectively. Variation of rOAD was within 0.35 mm over 10cm for both protons and carbon ions. Accuracy of measuring relative distal range using the ramping block was 0.2mm. Measured range over repeated three times for each range were within 0.25mm at same room, and within 1.0mm between four rooms. Conclusions: The optical dosimeter could efficiently measure the virtual source distance. And, to measure small range variation at different off-axial locations, and for the relative beam range between rooms during acceptance test of a modulated spot-scanning particle system.« less

Preliminary Calibration Report of an Apparatus to Measure Vibration Characteristics of Low Frequency Disturbance Source Devices

NASA Technical Reports Server (NTRS)

Russell, James W.; Marshall, Robert A.; Finley, Tom D.; Lawrence, George F.

1994-01-01

This report presents a description of the test apparatus and the method of testing the low frequency disturbance source characteristics of small pumps, fans, camera motors, and recorders that are typical of those used in microgravity science facilities. The test apparatus will allow both force and acceleration spectra of these disturbance devices to be obtained from acceleration measurements over the frequency range from 2 to 300 Hz. Some preliminary calibration results are presented.

Fundamentals of dielectric properties measurements and agricultural applications.

PubMed

Nelson, Stuart O

2010-01-01

Dielectrics and dielectric properties are defined generally and dielectric measurement methods and equipment are described for various frequency ranges from audio frequencies through microwave frequencies. These include impedance and admittance bridges, resonant frequency, transmission-line, and free-space methods in the frequency domain and time-domain and broadband techniques. Many references are cited describing methods in detail and giving sources of dielectric properties data. Finally a few applications for such data are presented and sources of tabulated and dielectric properties data bases are identified.

Dependence with air density of the response of the PTW SourceCheck ionization chamber for low energy brachytherapy sources.

PubMed

Tornero-López, Ana M; Guirado, Damián; Perez-Calatayud, Jose; Ruiz-Arrebola, Samuel; Simancas, Fernando; Gazdic-Santic, Maja; Lallena, Antonio M

2013-12-01

Air-communicating well ionization chambers are commonly used to assess air kerma strength of sources used in brachytherapy. The signal produced is supposed to be proportional to the air density within the chamber and, therefore, a density-independent air kerma strength is obtained when the measurement is corrected to standard atmospheric conditions using the usual temperature and pressure correction factor. Nevertheless, when assessing low energy sources, the ionization chambers may not fulfill that condition and a residual density dependence still remains after correction. In this work, the authors examined the behavior of the PTW 34051 SourceCheck ionization chamber when measuring the air kerma strength of (125)I seeds. Four different SourceCheck chambers were analyzed. With each one of them, two series of measurements of the air kerma strength for (125)I selectSeed(TM) brachytherapy sources were performed inside a pressure chamber and varying the pressure in a range from 747 to 1040 hPa (560 to 780 mm Hg). The temperature and relative humidity were kept basically constant. An analogous experiment was performed by taking measurements at different altitudes above sea level. Contrary to other well-known ionization chambers, like the HDR1000 PLUS, in which the temperature-pressure correction factor overcorrects the measurements, in the SourceCheck ionization chamber they are undercorrected. At a typical atmospheric situation of 933 hPa (700 mm Hg) and 20 °C, this undercorrection turns out to be 1.5%. Corrected measurements show a residual linear dependence on the density and, as a consequence, an additional density dependent correction must be applied. The slope of this residual linear density dependence is different for each SourceCheck chamber investigated. The results obtained by taking measurements at different altitudes are compatible with those obtained with the pressure chamber. Variations of the altitude and changes in the weather conditions may produce significant density corrections, and that effect should be taken into account. This effect is chamber-dependent, indicating that a specific calibration is necessary for each particular chamber. To our knowledge, this correction has not been considered so far for SourceCheck ionization chambers, but its magnitude cannot be neglected in clinical practice. The atmospheric pressure and temperature at which the chamber was calibrated need to be taken into account, and they should be reported in the calibration certificate. In addition, each institution should analyze the particular response of its SourceCheck ionization chamber and compute the adequate correction factors. In the absence of a suitable pressure chamber, a possibility for this assessment is to take measurements at different altitudes, spanning a wide enough air density range.

Dependence with air density of the response of the PTW SourceCheck ionization chamber for low energy brachytherapy sources

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

Tornero-López, Ana M.; Guirado, Damián; Ruiz-Arrebola, Samuel

2013-12-15

Purpose: Air-communicating well ionization chambers are commonly used to assess air kerma strength of sources used in brachytherapy. The signal produced is supposed to be proportional to the air density within the chamber and, therefore, a density-independent air kerma strength is obtained when the measurement is corrected to standard atmospheric conditions using the usual temperature and pressure correction factor. Nevertheless, when assessing low energy sources, the ionization chambers may not fulfill that condition and a residual density dependence still remains after correction. In this work, the authors examined the behavior of the PTW 34051 SourceCheck ionization chamber when measuring themore » air kerma strength of {sup 125}I seeds.Methods: Four different SourceCheck chambers were analyzed. With each one of them, two series of measurements of the air kerma strength for {sup 125}I selectSeed{sup TM} brachytherapy sources were performed inside a pressure chamber and varying the pressure in a range from 747 to 1040 hPa (560 to 780 mm Hg). The temperature and relative humidity were kept basically constant. An analogous experiment was performed by taking measurements at different altitudes above sea level.Results: Contrary to other well-known ionization chambers, like the HDR1000 PLUS, in which the temperature-pressure correction factor overcorrects the measurements, in the SourceCheck ionization chamber they are undercorrected. At a typical atmospheric situation of 933 hPa (700 mm Hg) and 20 °C, this undercorrection turns out to be 1.5%. Corrected measurements show a residual linear dependence on the density and, as a consequence, an additional density dependent correction must be applied. The slope of this residual linear density dependence is different for each SourceCheck chamber investigated. The results obtained by taking measurements at different altitudes are compatible with those obtained with the pressure chamber.Conclusions: Variations of the altitude and changes in the weather conditions may produce significant density corrections, and that effect should be taken into account. This effect is chamber-dependent, indicating that a specific calibration is necessary for each particular chamber. To our knowledge, this correction has not been considered so far for SourceCheck ionization chambers, but its magnitude cannot be neglected in clinical practice. The atmospheric pressure and temperature at which the chamber was calibrated need to be taken into account, and they should be reported in the calibration certificate. In addition, each institution should analyze the particular response of its SourceCheck ionization chamber and compute the adequate correction factors. In the absence of a suitable pressure chamber, a possibility for this assessment is to take measurements at different altitudes, spanning a wide enough air density range.« less

In situ measurement of low-Z material coating thickness on high Z substrate for tokamaks.

PubMed

Mueller, D; Roquemore, A L; Jaworski, M; Skinner, C H; Miller, J; Creely, A; Raman, P; Ruzic, D

2014-11-01

Rutherford backscattering of energetic particles can be used to determine the thickness of a coating of a low-Z material over a heavier substrate. Simulations indicate that 5 MeV alpha particles from an (241)Am source can be used to measure the thickness of a Li coating on Mo tiles between 0.5 and 15 μm thick. Using a 0.1 mCi source, a thickness measurement can be accomplished in 2 h of counting. This technique could be used to measure any thin, low-Z material coating (up to 1 mg/cm(2) thick) on a high-Z substrate, such as Be on W, B on Mo, or Li on Mo. By inserting a source and detector on a moveable probe, this technique could be used to provide an in situ measurement of the thickness of Li coating on NSTX-U Mo tiles. A test stand with an alpha source and an annular solid-state detector was used to investigate the measurable range of low-Z material thicknesses on Mo tiles.

In situ measurement of low-Z material coating thickness on high Z substrate for tokamaks

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

Mueller, D., E-mail: dmueller@pppl.gov; Roquemore, A. L.; Jaworski, M.

Rutherford backscattering of energetic particles can be used to determine the thickness of a coating of a low-Z material over a heavier substrate. Simulations indicate that 5 MeV alpha particles from an {sup 241}Am source can be used to measure the thickness of a Li coating on Mo tiles between 0.5 and 15 μm thick. Using a 0.1 mCi source, a thickness measurement can be accomplished in 2 h of counting. This technique could be used to measure any thin, low-Z material coating (up to 1 mg/cm{sup 2} thick) on a high-Z substrate, such as Be on W, B on Mo, or Limore » on Mo. By inserting a source and detector on a moveable probe, this technique could be used to provide an in situ measurement of the thickness of Li coating on NSTX-U Mo tiles. A test stand with an alpha source and an annular solid-state detector was used to investigate the measurable range of low-Z material thicknesses on Mo tiles.« less

Measurements of Transatmospheric Attenuation Statistics at the Microwave Frequencies : 15, 19, and 34 GHz

DOT National Transportation Integrated Search

1971-06-01

Attenuation statistics resulting from a twelve month observation program are presented. The sun is used as a source of microwave radiation. The dynamic range of atmospheric attenuation measurement capability is in excess of 30 dB. Solar radiation cha...

Near-Infrared Spectroscopy Using a Supercontinuum Laser: Application to Long Wavelength Transmission Spectra of Barley Endosperm and Oil.

PubMed

Ringsted, Tine; Dupont, Sune; Ramsay, Jacob; Jespersen, Birthe Møller; Sørensen, Klavs Martin; Keiding, Søren Rud; Engelsen, Søren Balling

2016-07-01

The supercontinuum laser is a new type of light source, which combines the collimation and intensity of a laser with the broad spectral region of a lamp. Using such a source therefore makes it possible to focus the light onto small sample areas without losing intensity and thus facilitate either rapid or high-intensity measurements. Single seed transmission analysis in the long wavelength (LW) near-infrared (NIR) region is one area that might benefit from a brighter light source such as the supercontinuum laser. This study is aimed at building an experimental spectrometer consisting of a supercontinuum laser source and a dispersive monochromator in order to investigate its capability to measure the barley endosperm using transmission experiments in the LW NIR region. So far, barley and wheat seeds have only been studied using NIR transmission in the short wavelength region up to 1100 nm. However, the region in the range of 2260-2380 nm has previously shown to be particularly useful in differentiating barley phenotypes using NIR spectroscopy in reflectance mode. In the present study, 350 seeds (consisting of 70 seeds from each of five barley genotypes) in 1 mm slices were measured by NIR transmission in the range of 2235-2381 nm and oils from the same five barley genotypes were measured in a cuvette with a 1 mm path length in the range of 2003-2497 nm. The spectra of the barley seeds could be classified according to genotypes by principal component analysis; and spectral covariances with reference analysis of moisture, β-glucan, starch, protein and lipid were established. The spectral variations of the barley oils were compared to the fatty acid compositions as measured using gas chromotography-mass spectrometry (GC-MS). © The Author(s) 2016.

Stochastic and Resolvable Gravitational Waves from Ultralight Bosons

NASA Astrophysics Data System (ADS)

Brito, Richard; Ghosh, Shrobana; Barausse, Enrico; Berti, Emanuele; Cardoso, Vitor; Dvorkin, Irina; Klein, Antoine; Pani, Paolo

2017-09-01

Ultralight scalar fields around spinning black holes can trigger superradiant instabilities, forming a long-lived bosonic condensate outside the horizon. We use numerical solutions of the perturbed field equations and astrophysical models of massive and stellar-mass black hole populations to compute, for the first time, the stochastic gravitational-wave background from these sources. In optimistic scenarios the background is observable by Advanced LIGO and LISA for field masses ms in the range ˜[2 ×10-13,10-12] and ˜5 ×[10-19,10-16] eV , respectively, and it can affect the detectability of resolvable sources. Our estimates suggest that an analysis of the stochastic background limits from LIGO O1 might already be used to marginally exclude axions with mass ˜10-12.5 eV . Semicoherent searches with Advanced LIGO (LISA) should detect ˜15 (5 ) to 200(40) resolvable sources for scalar field masses 3 ×10-13 (10-17) eV . LISA measurements of massive BH spins could either rule out bosons in the range ˜[10-18,2 ×10-13] eV , or measure ms with 10% accuracy in the range ˜[10-17,10-13] eV .

An empirical formula to calculate the full energy peak efficiency of scintillation detectors.

PubMed

Badawi, Mohamed S; Abd-Elzaher, Mohamed; Thabet, Abouzeid A; El-khatib, Ahmed M

2013-04-01

This work provides an empirical formula to calculate the FEPE for different detectors using the effective solid angle ratio derived from experimental measurements. The full energy peak efficiency (FEPE) curves of the (2″(*)2″) NaI(Tl) detector at different seven axial distances from the detector were depicted in a wide energy range from 59.53 to 1408keV using standard point sources. The distinction was based on the effects of the source energy and the source-to-detector distance. A good agreement was noticed between the measured and calculated efficiency values for the source-to-detector distances at 20, 25, 30, 35, 40, 45 and 50cm. Copyright © 2012 Elsevier Ltd. All rights reserved.

Infrared upconversion for astronomical applications. [laser applications to astronomical spectroscopy of infrared spectra

NASA Technical Reports Server (NTRS)

Abbas, M. M.; Kostiuk, T.; Ogilvie, K. W.

1975-01-01

The performance of an upconversion system is examined for observation of astronomical sources in the low to middle infrared spectral range. Theoretical values for the performance parameters of an upconversion system for astronomical observations are evaluated in view of the conversion efficiencies, spectral resolution, field of view, minimum detectable source brightness and source flux. Experimental results of blackbody measurements and molecular absorption spectrum measurements using a lithium niobate upconverter with an argon-ion laser as the pump are presented. Estimates of the expected optimum sensitivity of an upconversion device which may be built with the presently available components are given.

Accuracy of quantum sensors measuring yield photon flux and photosynthetic photon flux

NASA Technical Reports Server (NTRS)

Barnes, C.; Tibbitts, T.; Sager, J.; Deitzer, G.; Bubenheim, D.; Koerner, G.; Bugbee, B.; Knott, W. M. (Principal Investigator)

1993-01-01

Photosynthesis is fundamentally driven by photon flux rather than energy flux, but not all absorbed photons yield equal amounts of photosynthesis. Thus, two measures of photosynthetically active radiation have emerged: photosynthetic photon flux (PPF), which values all photons from 400 to 700 nm equally, and yield photon flux (YPF), which weights photons in the range from 360 to 760 nm according to plant photosynthetic response. We selected seven common radiation sources and measured YPF and PPF from each source with a spectroradiometer. We then compared these measurements with measurements from three quantum sensors designed to measure YPF, and from six quantum sensors designed to measure PPF. There were few differences among sensors within a group (usually <5%), but YPF values from sensors were consistently lower (3% to 20%) than YPF values calculated from spectroradiometric measurements. Quantum sensor measurements of PPF also were consistently lower than PPF values calculated from spectroradiometric measurements, but the differences were <7% for all sources, except red-light-emitting diodes. The sensors were most accurate for broad-band sources and least accurate for narrow-band sources. According to spectroradiometric measurements, YPF sensors were significantly less accurate (>9% difference) than PPF sensors under metal halide, high-pressure sodium, and low-pressure sodium lamps. Both sensor types were inaccurate (>18% error) under red-light-emitting diodes. Because both YPF and PPF sensors are imperfect integrators, and because spectroradiometers can measure photosynthetically active radiation much more accurately, researchers should consider developing calibration factors from spectroradiometric data for some specific radiation sources to improve the accuracy of integrating sensors.

Las Vegas Basin Seismic Response Project: Measured Shallow Soil Velocities

NASA Astrophysics Data System (ADS)

Luke, B. A.; Louie, J.; Beeston, H. E.; Skidmore, V.; Concha, A.

2002-12-01

The Las Vegas valley in Nevada is a deep (up to 5 km) alluvial basin filled with interlayered gravels, sands, and clays. The climate is arid. The water table ranges from a few meters to many tens of meters deep. Laterally extensive thin carbonate-cemented lenses are commonly found across parts of the valley. Lenses range beyond 2 m in thickness, and occur at depths exceeding 200 m. Shallow seismic datasets have been collected at approximately ten sites around the Las Vegas valley, to characterize shear and compression wave velocities in the near surface. Purposes for the surveys include modeling of ground response to dynamic loads, both natural and manmade, quantification of soil stiffness to aid structural foundation design, and non-intrusive materials identification. Borehole-based measurement techniques used include downhole and crosshole, to depths exceeding 100 m. Surface-based techniques used include refraction and three different methods involving inversion of surface-wave dispersion datasets. This latter group includes two active-source techniques, the Spectral Analysis of Surface Waves (SASW) method and the Multi-Channel Analysis of Surface Waves (MASW) method; and a new passive-source technique, the Refraction Mictrotremor (ReMi) method. Depths to halfspace for the active-source measurements ranged beyond 50 m. The passive-source method constrains shear wave velocities to 100 m depths. As expected, the stiff cemented layers profoundly affect local velocity gradients. Scale effects are evident in comparisons of (1) very local measurements typified by borehole methods, to (2) the broader coverage of the SASW and MASW measurements, to (3) the still broader and deeper resolution made possible by the ReMi measurements. The cemented layers appear as sharp spikes in the downhole datasets and are problematic in crosshole measurements due to refraction. The refraction method is useful only to locate the depth to the uppermost cemented layer. The surface-wave methods, on the other hand, can process velocity inversions. With the broader coverage of the active-source surface wave measurements, through careful inversion that takes advantage of prior information to the greatest extent possible, multiple, shallow, stiff layers can be resolved. Data from such broader-coverage methods also provide confidence regarding continuity of the cemented layers. For the ReMi measurements, which provide the broadest coverage of all methods used, the more generalized shallow profile is sometimes characterized by a strong stiffness inversion at a depth of approximately 10 m. We anticipate that this impedance contrast represents the vertical extent of the multiple layered deposits of cemented media.

Improved measurement linearity and precision for AMCW time-of-flight range imaging cameras.

PubMed

Payne, Andrew D; Dorrington, Adrian A; Cree, Michael J; Carnegie, Dale A

2010-08-10

Time-of-flight range imaging systems utilizing the amplitude modulated continuous wave (AMCW) technique often suffer from measurement nonlinearity due to the presence of aliased harmonics within the amplitude modulation signals. Typically a calibration is performed to correct these errors. We demonstrate an alternative phase encoding approach that attenuates the harmonics during the sampling process, thereby improving measurement linearity in the raw measurements. This mitigates the need to measure the system's response or calibrate for environmental changes. In conjunction with improved linearity, we demonstrate that measurement precision can also be increased by reducing the duty cycle of the amplitude modulated illumination source (while maintaining overall illumination power).

An analysis of source structure effects in radio interferometry measurements

NASA Technical Reports Server (NTRS)

Thomas, J. B.

1980-01-01

To begin a study of structure effects, this report presents a theoretical framework, proposes an effective position approach to structure corrections based on brightness distribution measurements, and analyzes examples of analytical and measured brightness distributions. Other topics include the effect of the frequency dependence of a brightness distribution on bandwidth synthesis (BWS) delay, the determination of the absolute location of a measured brightness distribution, and structure effects in dual frequency calibration of charged particle delays. For the 10 measured distributions analyzed, it was found that the structure effect in BWS delay at X-band (3.6 cm) can reach 30 cm, but typically falls in the range of 0 to 5 cm. A trial limit equation that is dependent on visibility was successfully tested against the 10 measured brightness distributions (seven sources). If the validity of this particular equation for an upper limit can be established for nearly all sources, the structure effect in BWS delay could be greatly reduced without supplementary measurements of brightness distributions.

Reciprocity relationships in vector acoustics and their application to vector field calculations.

PubMed

Deal, Thomas J; Smith, Kevin B

2017-08-01

The reciprocity equation commonly stated in underwater acoustics relates pressure fields and monopole sources. It is often used to predict the pressure measured by a hydrophone for multiple source locations by placing a source at the hydrophone location and calculating the field everywhere for that source. A similar equation that governs the orthogonal components of the particle velocity field is needed to enable this computational method to be used for acoustic vector sensors. This paper derives a general reciprocity equation that accounts for both monopole and dipole sources. This vector-scalar reciprocity equation can be used to calculate individual components of the received vector field by altering the source type used in the propagation calculation. This enables a propagation model to calculate the received vector field components for an arbitrary number of source locations with a single model run for each vector field component instead of requiring one model run for each source location. Application of the vector-scalar reciprocity principle is demonstrated with analytic solutions for a range-independent environment and with numerical solutions for a range-dependent environment using a parabolic equation model.

Stereotypical rapid source level regulation in the harbour porpoise biosonar

NASA Astrophysics Data System (ADS)

Linnenschmidt, Meike; Kloepper, Laura N.; Wahlberg, Magnus; Nachtigall, Paul E.

2012-09-01

Some odontocetes and bats vary both click intensity and receiver sensitivity during echolocation, depending on target range. It is not known how this so-called automatic gain control is regulated by the animal. The source level of consecutive echolocation clicks from a harbour porpoise was measured with a hydrophone array while the animal detected an aluminium cylinder at 2, 4 or 8 m distance in a go/no-go paradigm. On-axis clicks had source levels of 145-174 dB re 1 μPa peak-to-peak. During target-present trials the click trains reached comparable source levels independent of the range to the target after three clicks. After an additional click, the source level was reduced for the 2 and 4 m trials until it equalled the one-way transmission loss. During target-absent trials, the source level remained high throughout the entire click train. Given typical values of harbour porpoise inter-click intervals, the source level reduction commenced within a few 100 ms from the first click in the click train. This may indicate a sub-cortically regulated source level regulation in the harbour porpoise.

Using stable isotopes of hydrogen to quantify biogenic and thermogenic atmospheric methane sources: A case study from the Colorado Front Range

NASA Astrophysics Data System (ADS)

Townsend-Small, Amy; Botner, E. Claire; Jimenez, Kristine L.; Schroeder, Jason R.; Blake, Nicola J.; Meinardi, Simone; Blake, Donald R.; Sive, Barkley C.; Bon, Daniel; Crawford, James H.; Pfister, Gabriele; Flocke, Frank M.

2016-11-01

Global atmospheric concentrations of methane (CH4), a powerful greenhouse gas, are increasing, but because there are many natural and anthropogenic sources of CH4, it is difficult to assess which sources may be increasing in magnitude. Here we present a data set of δ2H-CH4 measurements of individual sources and air in the Colorado Front Range, USA. We show that δ2H-CH4, but not δ13C, signatures are consistent in air sampled downwind of landfills, cattle feedlots, and oil and gas wells in the region. Applying these source signatures to air in ground and aircraft samples indicates that at least 50% of CH4 emitted in the region is biogenic, perhaps because regulatory restrictions on leaking oil and natural gas wells are helping to reduce this source of CH4. Source apportionment tracers such as δ2H may help close the gap between CH4 observations and inventories, which may underestimate biogenic as well as thermogenic sources.

Multiwavelength pyrometer for gray and non-gray surfaces in the presence of interfering radiation

NASA Technical Reports Server (NTRS)

Ng, Daniel L. P. (Inventor)

1994-01-01

A method and apparatus for detecting the temperature of gray and non-gray bodies in the presence of interfering radiation are presented. A gray body has a constant emissivity less than 1 and a non-gray body has an emissivity which varies with wavelength. The emissivity and reflectivity of the surface is determined over a range of wavelengths. Spectra are also measured of the extraneous interference radiation source and the surface of the object to be measured in the presence of the extraneous interference radiation source. An auxiliary radiation source is used to determine the reflectivity of the surface and also the emissivity. The measured spectrum of the surfaces in the presence of the extraneous interference radiation source is set equal to the emissivity of the surface multiplied by a Planck function containing a temperature term T plus the surface reflectivity multiplied by the spectrum of the extraneous interference radiation source. The equation is then solved for T to determine the temperature of the surface.

Simulation of angular and energy distributions of the PTB beta secondary standard.

PubMed

Faw, R E; Simons, G G; Gianakon, T A; Bayouth, J E

1990-09-01

Calculations and measurements have been performed to assess radiation doses delivered by the PTB Secondary Standard that employs 147Pm, 204Tl, and 90Sr:90Y sources in prescribed geometries, and features "beam-flattening" filters to assure uniformity of delivered doses within a 5-cm radius of the axis from source to detector plane. Three-dimensional, coupled, electron-photon Monte Carlo calculations, accounting for transmission through the source encapsulation and backscattering from the source mounting, led to energy spectra and angular distributions of electrons penetrating the source encapsulation that were used in the representation of pseudo sources of electrons for subsequent transport through the atmosphere, filters, and detectors. Calculations were supplemented by measurements made using bare LiF TLD chips on a thick polymethyl methacrylate phantom. Measurements using the 204Tl and 90Sr:90Y sources revealed that, even in the absence of the beam-flattening filters, delivered dose rates were very uniform radially. Dosimeter response functions (TLD:skin dose ratios) were calculated and confirmed experimentally for all three beta-particle sources and for bare LiF TLDs ranging in mass thickness from 10 to 235 mg cm-2.

A database for the static dielectric constant of water and steam

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

Fernandez, D.P.; Mulev, Y.; Goodwin, A.R.H.

All reliable sources of data for the static dielectric constant or relative permittivity of water and steam, many of them unpublished or inaccessible, have been collected, evaluated, corrected when required, and converted to the ITS-90 temperature scale. The data extend over a temperature range from 238 to 873 K and over a pressure range from 0.1 MPa up to 1189 MPa. The evaluative part of this work includes a review of the different types of measurement techniques, and the corrections for frequency dependence due to the impedance of circuit components, and to electrode polarization. It also includes a detailed assessmentmore » of the uncertainty of each particular data source, as compared to other sources in the same range of pressure and temperature. Both the raw and the corrected data have been tabulated, and are also available on diskette. A comprehensive list of references to the literature is included.« less

Experimental verification of enhanced sound transmission from water to air at low frequencies.

PubMed

Calvo, David C; Nicholas, Michael; Orris, Gregory J

2013-11-01

Laboratory measurements of enhanced sound transmission from water to air at low frequencies are presented. The pressure at a monitoring hydrophone is found to decrease for shallow source depths in agreement with the classical theory of a monopole source in proximity to a pressure release interface. On the other hand, for source depths below 1/10 of an acoustic wavelength in water, the radiation pattern in the air measured by two microphones becomes progressively omnidirectional in contrast to the classical geometrical acoustics picture in which sound is contained within a cone of 13.4° half angle. The measured directivities agree with wavenumber integration results for a point source over a range of frequencies and source depths. The wider radiation pattern owes itself to the conversion of evanescent waves in the water into propagating waves in the air that fill the angular space outside the cone. A ratio of pressure measurements made using an on-axis microphone and a near-axis hydrophone are also reported and compared with theory. Collectively, these pressure measurements are consistent with the theory of anomalous transparency of the water-air interface in which a large fraction of acoustic power emitted by a shallow source is radiated into the air.

Mapping and defining sources of variability in bioavailable strontium isotope ratios in the Eastern Mediterranean

NASA Astrophysics Data System (ADS)

Hartman, Gideon; Richards, Mike

2014-02-01

The relative contributions of bedrock and atmospheric sources to bioavailable strontium (Sr) pools in local soils was studied in Northern Israel and the Golan regions through intensive systematic sampling of modern plants and invertebrates, to produce a map of modern bioavailable strontium isotope ratios (87Sr/86Sr) for regional reconstructions of human and animal mobility patterns. The study investigates sources of variability in bioavailable 87Sr/86Sr ratios, in particular the intra-and inter-site range of variation in plant 87Sr/86Sr ratios, the range of 87Sr/86Sr ratios of plants growing on marine sedimentary versus volcanic geologies, the differences between ligneous and non-ligneous plants with varying growth and water utilization strategies, and the relative contribution of atmospheric Sr sources from different soil and vegetation types and climatic zones. Results indicate predictable variation in 87Sr/86Sr ratios. Inter- and intra-site differences in bioavailable 87Sr/86Sr ratios average of 0.00025, while the range of 87Sr/86Sr ratios measured regionally in plants and invertebrates is 0.7090 in Pleistocene calcareous sandstone and 0.7074 in mid-Pleistocene volcanic pyroclast. The 87Sr/86Sr ratios measured in plants growing on volcanic bedrock show time dependent increases in atmospheric deposition relative to bedrock weathering. The 87Sr/86Sr ratios measured in plants growing on renzina soils depends on precipitation. The spacing between bedrock 87Sr/86Sr ratios and plants is highest in wet conditions and decreases in dry conditions. The 87Sr/86Sr ratios measured in plants growing on terra rossa soils is relatively constant (0.7085) regardless of precipitation. Ligneous plants are typically closer to bedrock 87Sr/86Sr ratios than non-ligneous plants. Since the bioavailable 87Sr/86Sr ratios currently measured in the region reflect a mix of both exogenous and endogenous sources, changes in the relative contribution of exogenous sources can cause variation over time. Precipitation, the age of the bedrock and the overall Sr concentration must to be taken into consideration when interpreting geographical variation in strontium isotopes throughout a region. Because these factors can change through time, we recommend that Sr data from time periods older than the Holocene be interpreted with caution. What is the range of variation in the 87Sr/86Sr ratios of vegetation within individual sampling locales? Are there differences in the 87Sr/86Sr ratios of ligneous (woody plants) and non-ligneous (herbaceous plants) within a single sampling location? What is the range of variability in the 87Sr/86Sr ratios of plants growing on marine sedimentary and volcanic geologies? How do the relative contributions of atmospheric Sr sources vary with geology, precipitation, distance from the sea, soil type, and vegetation type. Outlining Sr variability will enable the prediction of the Sr ratio of herbivores in various ecological niches as well as the mapping of bioavailable Sr ratios for a range of pre-Holocene landscapes.In contrast to previous mapping efforts in the region (Shewan, 2004; Perry et al., 2009), this study takes a systematic approach that examines the relative contribution of atmospherically deposited Sr and local weathered bedrock Sr sources to local bioavailable 87Sr/86Sr pools. This is based on the intensive sampling of plants and herbivorous invertebrates primarily from volcanic landscapes and marine sedimentary landscapes composed by large of limestone, dolomite, chalk and marl. The repeated sampling of individual locales, and comparisons between distinct locales of the same geological outcrops were initially planned to detemine the degree of homogeneity of bioavailable 87Sr/86Sr ratios for the purpose of regional landscape mapping. This is important due to the current lack of data on microscale variation in bioavailable sources that might limit the degree of separation between different exposures.

Predicting the digestible energy of corn determined with growing swine from nutrient composition and cross-species measurements.

PubMed

Smith, B; Hassen, A; Hinds, M; Rice, D; Jones, D; Sauber, T; Iiams, C; Sevenich, D; Allen, R; Owens, F; McNaughton, J; Parsons, C

2015-03-01

The DE values of corn grain for pigs will differ among corn sources. More accurate prediction of DE may improve diet formulation and reduce diet cost. Corn grain sources ( = 83) were assayed with growing swine (20 kg) in DE experiments with total collection of feces, with 3-wk-old broiler chick in nitrogen-corrected apparent ME (AME) trials and with cecectomized adult roosters in nitrogen-corrected true ME (TME) studies. Additional AME data for the corn grain source set was generated based on an existing near-infrared transmittance prediction model (near-infrared transmittance-predicted AME [NIT-AME]). Corn source nutrient composition was determined by wet chemistry methods. These data were then used to 1) test the accuracy of predicting swine DE of individual corn sources based on available literature equations and nutrient composition and 2) develop models for predicting DE of sources from nutrient composition and the cross-species information gathered above (AME, NIT-AME, and TME). The overall measured DE, AME, NIT-AME, and TME values were 4,105 ± 11, 4,006 ± 10, 4,004 ± 10, and 4,086 ± 12 kcal/kg DM, respectively. Prediction models were developed using 80% of the corn grain sources; the remaining 20% was reserved for validation of the developed prediction equation. Literature equations based on nutrient composition proved imprecise for predicting corn DE; the root mean square error of prediction ranged from 105 to 331 kcal/kg, an equivalent of 2.6 to 8.8% error. Yet among the corn composition traits, 4-variable models developed in the current study provided adequate prediction of DE (model ranging from 0.76 to 0.79 and root mean square error [RMSE] of 50 kcal/kg). When prediction equations were tested using the validation set, these models had a 1 to 1.2% error of prediction. Simple linear equations from AME, NIT-AME, or TME provided an accurate prediction of DE for individual sources ( ranged from 0.65 to 0.73 and RMSE ranged from 50 to 61 kcal/kg). Percentage error of prediction based on the validation data set was greater (1.4%) for the TME model than for the NIT-AME or AME models (1 and 1.2%, respectively), indicating that swine DE values could be accurately predicted by using AME or NIT-AME. In conclusion, regression equations developed from broiler measurements or from analyzed nutrient composition proved adequate to reliably predict the DE of commercially available corn hybrids for growing pigs.

All-Solid-State 2.45-to-2.78-THz Source

NASA Technical Reports Server (NTRS)

Mehdi, Imran; Chattopadhyay, Goutam; Schlecht, Erich T.; Lin, Robert H.; Sin, Seith; Peralta, Alejandro; Lee, Choonsup; Gill, John J.; Pearson, John C.; Goldsmith, Paul F.;

Effective temperature of an ultracold electron source based on near-threshold photoionization.

PubMed

Engelen, W J; Smakman, E P; Bakker, D J; Luiten, O J; Vredenbregt, E J D

2014-01-01

We present a detailed description of measurements of the effective temperature of a pulsed electron source, based on near-threshold photoionization of laser-cooled atoms. The temperature is determined by electron beam waist scans, source size measurements with ion beams, and analysis with an accurate beam line model. Experimental data is presented for the source temperature as a function of the wavelength of the photoionization laser, for both nanosecond and femtosecond ionization pulses. For the nanosecond laser, temperatures as low as 14 ± 3 K were found; for femtosecond photoionization, 30 ± 5 K is possible. With a typical source size of 25 μm, this results in electron bunches with a relative transverse coherence length in the 10⁻⁴ range and an emittance of a few nm rad. © 2013 Elsevier B.V. All rights reserved.

A reference aerosol for a radon reference chamber

NASA Astrophysics Data System (ADS)

Paul, Annette; Keyser, Uwe

1996-02-01

The measurement of radon and radon progenies and the calibration of their detection systems require the production and measurement of aerosols well-defined in size and concentration. In the German radon reference chamber, because of its unique chemical and physical properties, carnauba wax is used to produce standard aerosols. The aerosol size spectra are measured on-line by an aerosol measurement system in the range of 10 nm to 1 μm aerodynamic diameter. The experimental set-ups for the study of adsorption of radioactive ions on aerosols as function of their size and concentration will be described, the results presented and further adaptations for an aerosol jet introduced (for example, for the measurement of short-lived neutron-rich isotopes). Data on the dependence of aerosol radius, ion concentration and element selectivity is collected by using a 252Cf-sf source. The fission products of this source range widely in elements, isotopes and charges. Adsorption and the transport of radioactive ions on aerosols have therefore been studied for various ions for the first time, simultaneously with the aerosol size on-line spectrometry.

Carbon nanotube vacuum gauges with wide-dynamic range and processes thereof

NASA Technical Reports Server (NTRS)

Manohara, Harish (Inventor); Kaul, Anupama B. (Inventor)

2013-01-01

A miniature thermal conductivity gauge employs a carbon single-walled-nanotube. The gauge operates on the principle of thermal exchange between the voltage-biased nanotube and the surrounding gas at low levels of power and low temperatures to measure vacuum across a wide dynamic range. The gauge includes two terminals, a source of constant voltage to the terminals, a single-walled carbon nanotube between the terminals, a calibration of measured conductance of the nanotube to magnitudes of surrounding vacuum and a current meter in electrical communication with the source of constant voltage. Employment of the nanotube for measuring vacuum includes calibrating the electrical conductance of the nanotube to magnitudes of vacuum, exposing the nanotube to a vacuum, applying a constant voltage across the nanotube, measuring the electrical conductance of the nanotube in the vacuum with the constant voltage applied and converting the measured electrical conductance to the corresponding calibrated magnitude of vacuum using the calibration. The nanotube may be suspended to minimize heat dissipation through the substrate, increasing sensitivity at even tower pressures.

Atmospheric Ice-Nucleating Particles in the Dusty Tropical Atlantic

NASA Astrophysics Data System (ADS)

Price, H. C.; Baustian, K. J.; McQuaid, J. B.; Blyth, A.; Bower, K. N.; Choularton, T.; Cotton, R. J.; Cui, Z.; Field, P. R.; Gallagher, M.; Hawker, R.; Merrington, A.; Miltenberger, A.; Neely, R. R., III; Parker, S. T.; Rosenberg, P. D.; Taylor, J. W.; Trembath, J.; Vergara-Temprado, J.; Whale, T. F.; Wilson, T. W.; Young, G.; Murray, B. J.

2018-02-01

Desert dust is one of the most important atmospheric ice-nucleating aerosol species around the globe. However, there have been very few measurements of ice-nucleating particle (INP) concentrations in dusty air close to desert sources. In this study we report the concentration of INPs in dust laden air over the tropical Atlantic within a few days' transport of one of the world's most important atmospheric sources of desert dust, the Sahara. These measurements were performed as part of the Ice in Clouds Experiment-Dust campaign based in Cape Verde, during August 2015. INP concentrations active in the immersion mode, determined using a droplet-on-filter technique, ranged from around 102 m-3 at -12°C to around 105 m-3 at -23°C. There is about 2 orders of magnitude variability in INP concentration for a particular temperature, which is determined largely by the variability in atmospheric dust loading. These measurements were made at altitudes from 30 to 3,500 m in air containing a range of dust loadings. The ice active site density (ns) for desert dust dominated aerosol derived from our measurements agrees with several laboratory-based parameterizations for ice nucleation by desert dust within 1 to 2 orders of magnitude. The small variability in ns values determined from our measurements (within about 1 order of magnitude) is striking given that the back trajectory analysis suggests that the sources of dust were geographically diverse. This is consistent with previous work, which indicates that desert dust's ice-nucleating activity is only weakly dependent on source.

A 155-dB Dynamic Range Current Measurement Front End for Electrochemical Biosensing.

PubMed

Dai, Shanshan; Perera, Rukshan T; Yang, Zi; Rosenstein, Jacob K

2016-10-01

An integrated current measurement system with ultra wide dynamic range is presented and fabricated in a 180-nm CMOS technology. Its dual-mode design provides concurrent voltage and frequency outputs, without requiring an external clock source. An integrator-differentiator core provides a voltage output with a noise floor of 11.6 fA/ [Formula: see text] and a -3 dB cutoff frequency of 1.4 MHz. It is merged with an asynchronous current-to-frequency converter, which generates an output frequency linearly proportional to the input current. Together, the voltage and frequency outputs yield a current measurement range of 155 dB, spanning from 204 fA (100 Hz) or 1.25 pA (10 kHz) to 11.6 μA. The proposed architecture's low noise, wide bandwidth, and wide dynamic range make it ideal for measurements of highly nonlinear electrochemical and electrophysiological systems.

Chlorine isotope geochemistry of Icelandic thermal fluids: Implications for geothermal system behavior at divergent plate boundaries

NASA Astrophysics Data System (ADS)

Stefánsson, Andri; Barnes, Jaime D.

2016-09-01

The chlorine isotope composition of thermal fluids from Iceland were measured in order to evaluate the source of chlorine and possible chlorine isotope fractionation in geothermal systems at divergent plate boundaries. The geothermal systems studied have a wide range of reservoir temperatures from 40 to 437 °C and in-situ pH of 6.15 to 7.15. Chlorine concentrations range from 5.2 to 171 ppm and δ37 Cl values are -0.3 to + 2.1 ‰ (n = 38). The δ37 Cl values of the thermal fluids are interpreted to reflect the source of the chlorine in the fluids. Geothermal processes such as secondary mineral formation, aqueous and vapor speciation and boiling were found to have minimal effects on the δ37 Cl values. However, further work is needed on incorporation of Cl into secondary minerals and its effect on Cl isotope fractionation. Results of isotope geochemical modeling demonstrate that the range of δ37 Cl values documented in the natural thermal fluids can be explained by leaching of the basaltic rocks by meteoric source water under geothermal conditions. Magmatic gas partitioning may also contribute to the source of Cl in some cases. The range of δ37 Cl values of the fluids result mainly from the large range of δ37 Cl values observed for Icelandic basalts, which range from -0.6 to + 1.2 ‰.

Influence of frequency tuning and double-frequency heating on ions extracted from an electron cyclotron resonance ion source

NASA Astrophysics Data System (ADS)

Maimone, F.; Celona, L.; Lang, R.; Mäder, J.; Roßbach, J.; Spädtke, P.; Tinschert, K.

2011-12-01

The electromagnetic field within the plasma chamber of an electron cyclotron resonance ion source (ECRIS) and the properties of the plasma waves affect the plasma properties and ion beam production. We have experimentally investigated the "frequency tuning effect" and "double frequency heating" on the CAPRICE ECRIS device. A traveling wave tube amplifier, two microwave sweep generators, and a dedicated experimental set-up were used to carry out experiments in the 12.5-16.5 GHz frequency range. During the frequency sweeps the evolution of the intensity and shape of the extracted argon beam were measured together with the microwave reflection coefficient. A range of different ion source parameter settings was used. Here we describe these experiments and the resultant improved understanding of these operational modes of the ECR ion source.

Influence of frequency tuning and double-frequency heating on ions extracted from an electron cyclotron resonance ion source.

PubMed

Maimone, F; Celona, L; Lang, R; Mäder, J; Rossbach, J; Spädtke, P; Tinschert, K

2011-12-01

The electromagnetic field within the plasma chamber of an electron cyclotron resonance ion source (ECRIS) and the properties of the plasma waves affect the plasma properties and ion beam production. We have experimentally investigated the "frequency tuning effect" and "double frequency heating" on the CAPRICE ECRIS device. A traveling wave tube amplifier, two microwave sweep generators, and a dedicated experimental set-up were used to carry out experiments in the 12.5-16.5 GHz frequency range. During the frequency sweeps the evolution of the intensity and shape of the extracted argon beam were measured together with the microwave reflection coefficient. A range of different ion source parameter settings was used. Here we describe these experiments and the resultant improved understanding of these operational modes of the ECR ion source.

Broadband classification and statistics of echoes from aggregations of fish measured by long-range, mid-frequency sonar.

PubMed

Jones, Benjamin A; Stanton, Timothy K; Colosi, John A; Gauss, Roger C; Fialkowski, Joseph M; Michael Jech, J

2017-06-01

For horizontal-looking sonar systems operating at mid-frequencies (1-10 kHz), scattering by fish with resonant gas-filled swimbladders can dominate seafloor and surface reverberation at long-ranges (i.e., distances much greater than the water depth). This source of scattering, which can be difficult to distinguish from other sources of scattering in the water column or at the boundaries, can add spatio-temporal variability to an already complex acoustic record. Sparsely distributed, spatially compact fish aggregations were measured in the Gulf of Maine using a long-range broadband sonar with continuous spectral coverage from 1.5 to 5 kHz. Observed echoes, that are at least 15 decibels above background levels in the horizontal-looking sonar data, are classified spectrally by the resonance features as due to swimbladder-bearing fish. Contemporaneous multi-frequency echosounder measurements (18, 38, and 120 kHz) and net samples are used in conjunction with physics-based acoustic models to validate this approach. Furthermore, the fish aggregations are statistically characterized in the long-range data by highly non-Rayleigh distributions of the echo magnitudes. These distributions are accurately predicted by a computationally efficient, physics-based model. The model accounts for beam-pattern and waveguide effects as well as the scattering response of aggregations of fish.

What Do We Know about DOM Chemical Composition Based on Its Optical Properties?

NASA Astrophysics Data System (ADS)

Aiken, G.

2016-02-01

Dissolved organic matter (DOM) optical measurements (UV-Vis light absorbance and fluorescence) provide useful information related to DOM composition and reactivity, and can serve as proxies for DOM concentration and the concentrations of some metals, such as mercury. While these measurements are useful for a range of objectives, they only measure aromatic molecules that absorb UV-Vis light and a smaller subset of these molecules that fluoresce. They provide no information about the substantial fraction of DOM that is non-chromophoric. Based on chromatographic fractionation on XAD resins, DOM optical properties measured on whole water samples strongly correlate with both the concentration and composition of the hydrophobic acid (HPOA) fraction of the DOM. In this presentation the results of DOM optical measurements, DOM fractionation analyses, and 13C-nuclear magnetic resonance (NMR) and ultrahigh-resolution mass spectrometry (FTICR_MS) of HPOA fractions obtained from a wide range a natural waters will be presented to examine the relationships between DOM optical properties and DOM chemical composition. The HPOA fractions within and between rivers exhibit a wide range of optical behaviors reflective of sources and transformations compared to other DOM fractions. While, 13C-NMR and FTICR-MS analyses generally show greater relative concentrations of aromatic molecules for those samples with strong optical signals, they also indicate that the HPOA fractions are mostly composed of a large number of non-chromophoric molecules, such as carbohydrates carboxyl-rich alicyclic molecules (CRAM), and other aliphatic molecules, all of which have implications regarding DOM reactivity, biolability, sources, and age. The utility and short-comings of employing optical data for assessing sources and transformations of DOM in natural waters will be examined using case studies involving organic matter in the Yukon River Basin and riverine export of DOM to the Gulf of Maine.

Estimating methane emissions from dairies in the Los Angeles Basin

NASA Astrophysics Data System (ADS)

Viatte, C.; Lauvaux, T.; Hedelius, J.; Parker, H. A.; Chen, J.; Jones, T.; Franklin, J.; Deng, A.; Gaudet, B.; Duren, R. M.; Verhulst, K. R.; Wunch, D.; Roehl, C. M.; Dubey, M. K.; Wofsy, S.; Wennberg, P. O.

2015-12-01

Inventory estimates of methane (CH4) emissions among the individual sources (mainly agriculture, energy production, and waste management) remain highly uncertain at regional and urban scales. Accurate atmospheric measurements can provide independent estimates to evaluate bottom-up inventories, especially in urban region, where many different CH4 sources are often confined in relatively small areas. Among these sources, livestock emissions, which are mainly originating from dairy cows, account for ~55% of the total CH4 emissions in California in 2013. This study aims to rigorously estimate the amount of CH4 emitted by the largest dairies in the Southern California region by combining measurements from four mobile ground-based spectrometers (EM27/SUN), in situ isotopic methane measurements from a CRDS analyzer (Picarro), and a high-resolution atmospheric transport model (the Weather Research and Forecasting model) in Large-Eddy Simulation mode. The remote sensing spectrometers measure the total column-averaged dry-air mole fractions of CH4 and CO2 (XCH4 and XCO2) in the near infrared region, providing information about total emissions of the dairies. Gradients measured by the four EM27 ranged from 0.2 to 22 ppb and from 0.7 to 3 ppm for XCH4 and XCO2, respectively. To assess the fluxes of the dairies, measurements of these gradients are used in conjunction with the local atmospheric dynamics simulated at 111 m resolution. Inverse modelling from WRF-LES is employed to resolve the spatial distribution of CH4 emissions in the domain. A Bayesian inversion and a Monte-Carlo approach were used to provide the CH4 emissions over the dairy with their associated uncertainties. The isotopic δ13C sampled at different locations in the area ranges from -40 ‰ to -55 ‰, indicating a mixture of anthropogenic and biogenic sources.

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

Muryn, J; Wilkinson, D

Purpose: The purpose of this work is to evaluate a method for confirming source strength of I-125 seeds in a bulk assay while maintaining sterility and time efficiency. Methods: The I-125 seeds used in this study (STM 1251, Bard Brachytherapy, Inc.) were available as loose seeds or linked in 3, 4, or 5 seed configurations. A third party 10% assay (NIST traceable) is provided. Source strengths ranging from 0.395 to 0.504 U were available for this study. A stand was built out of aluminum to hold an exposure meter (Inovision (Fluke) 451P) at 25 cm above the I-125 sources tomore » measure the exposure rate. Three different seed configurations were measured: loose, linked, and loaded needles (Bard FastFil Seed Implant Needle). The measurements were made in an operating room, and a sterile sheet was used under the non-sterile aluminum stand. Seeds and needles were placed in a sterile tray. Results: One hundred forty-two loose seeds in 5 batches (0.395, 0.395, 0.409, 0.444, 0.444 U/seed) and 902 seeds in 7 batches containing various strands (0.444, 0.444,.0444, 0.466, 0.466, 0.504, 0.504 U/seed) were measured. The average exposure rate per unit activity was measured to be 0.593 mR per hr per U with a standard deviation of 0.016. The Result for loaded needles was 0.261 mR per hr per U with a standard deviation of 0.014. Once the apparatus is set up, measurements of 180 linked sources as supplied in the Bard package requires only a few minutes. Conclusion: The proposed method can confirm the activity of a batch of loose or stranded I-125 seeds within a range of 5%.« less

Broadband Radiometric LED Measurements

PubMed Central

Eppeldauer, G. P.; Cooksey, C. C.; Yoon, H. W.; Hanssen, L. M.; Podobedov, V. B.; Vest, R. E.; Arp, U.; Miller, C. C.

2017-01-01

At present, broadband radiometric measurements of LEDs with uniform and low-uncertainty results are not available. Currently, either complicated and expensive spectral radiometric measurements or broadband photometric LED measurements are used. The broadband photometric measurements are based on the CIE standardized V(λ) function, which cannot be used in the UV range and leads to large errors when blue or red LEDs are measured in its wings, where the realization is always poor. Reference irradiance meters with spectrally constant response and high-intensity LED irradiance sources were developed here to implement the previously suggested broadband radiometric LED measurement procedure [1, 2]. Using a detector with spectrally constant response, the broadband radiometric quantities of any LEDs or LED groups can be simply measured with low uncertainty without using any source standard. The spectral flatness of filtered-Si detectors and low-noise pyroelectric radiometers are compared. Examples are given for integrated irradiance measurement of UV and blue LED sources using the here introduced reference (standard) pyroelectric irradiance meters. For validation, the broadband measured integrated irradiance of several LED-365 sources were compared with the spectrally determined integrated irradiance derived from an FEL spectral irradiance lamp-standard. Integrated responsivity transfer from the reference irradiance meter to transfer standard and field UV irradiance meters is discussed. PMID:28649167

Broadband Radiometric LED Measurements.

PubMed

Eppeldauer, G P; Cooksey, C C; Yoon, H W; Hanssen, L M; Podobedov, V B; Vest, R E; Arp, U; Miller, C C

2016-01-01

At present, broadband radiometric measurements of LEDs with uniform and low-uncertainty results are not available. Currently, either complicated and expensive spectral radiometric measurements or broadband photometric LED measurements are used. The broadband photometric measurements are based on the CIE standardized V(λ) function, which cannot be used in the UV range and leads to large errors when blue or red LEDs are measured in its wings, where the realization is always poor. Reference irradiance meters with spectrally constant response and high-intensity LED irradiance sources were developed here to implement the previously suggested broadband radiometric LED measurement procedure [1, 2]. Using a detector with spectrally constant response, the broadband radiometric quantities of any LEDs or LED groups can be simply measured with low uncertainty without using any source standard. The spectral flatness of filtered-Si detectors and low-noise pyroelectric radiometers are compared. Examples are given for integrated irradiance measurement of UV and blue LED sources using the here introduced reference (standard) pyroelectric irradiance meters. For validation, the broadband measured integrated irradiance of several LED-365 sources were compared with the spectrally determined integrated irradiance derived from an FEL spectral irradiance lamp-standard. Integrated responsivity transfer from the reference irradiance meter to transfer standard and field UV irradiance meters is discussed.

Estimation of low-level neutron dose-equivalent rate by using extrapolation method for a curie level Am-Be neutron source.

PubMed

Li, Gang; Xu, Jiayun; Zhang, Jie

2015-01-01

Neutron radiation protection is an important research area because of the strong radiation biological effect of neutron field. The radiation dose of neutron is closely related to the neutron energy, and the connected relationship is a complex function of energy. For the low-level neutron radiation field (e.g. the Am-Be source), the commonly used commercial neutron dosimeter cannot always reflect the low-level dose rate, which is restricted by its own sensitivity limit and measuring range. In this paper, the intensity distribution of neutron field caused by a curie level Am-Be neutron source was investigated by measuring the count rates obtained through a 3 He proportional counter at different locations around the source. The results indicate that the count rates outside of the source room are negligible compared with the count rates measured in the source room. In the source room, 3 He proportional counter and neutron dosimeter were used to measure the count rates and dose rates respectively at different distances to the source. The results indicate that both the count rates and dose rates decrease exponentially with the increasing distance, and the dose rates measured by a commercial dosimeter are in good agreement with the results calculated by the Geant4 simulation within the inherent errors recommended by ICRP and IEC. Further studies presented in this paper indicate that the low-level neutron dose equivalent rates in the source room increase exponentially with the increasing low-energy neutron count rates when the source is lifted from the shield with different radiation intensities. Based on this relationship as well as the count rates measured at larger distance to the source, the dose rates can be calculated approximately by the extrapolation method. This principle can be used to estimate the low level neutron dose values in the source room which cannot be measured directly by a commercial dosimeter. Copyright © 2014 Elsevier Ltd. All rights reserved.

Use of stable sulfur isotopes to identify sources of sulfate in Rocky Mountain snowpacks

USGS Publications Warehouse

Mast, M.A.; Turk, J.T.; Ingersoll, G.P.; Clow, D.W.; Kester, C.L.

2001-01-01

Stable sulfur isotope ratios and major ions in bulk snowpack samples were monitored at a network of 52 high-elevation sites along and near the Continental Divide from 1993 to 1999. This information was collected to better define atmospheric deposition to remote areas of the Rocky Mountains and to help identify the major source regions of sulfate in winter deposition. Average annual ??34S values at individual sites ranged from + 4.0 to + 8.2??? and standard deviations ranged from 0.4 to 1.6???. The chemical composition of all samples was extremely dilute and slightly acidic; average sulfate concentrations ranged from 2.4 to 12.2 ??eql-1 and pH ranged from 4.82 to 5.70. The range of ??34S values measured in this study indicated that snowpack sulfur in the Rocky Mountains is primarily derived from anthropogenic sources. A nearly linear relation between ??34S and latitude was observed for sites in New Mexico, Colorado, and southern Wyoming, which indicates that snowpack sulfate in the southern part of the network was derived from two isotopically distinct source regions. Because the major point sources of SO2 in the region are coal-fired powerplants, this pattern may reflect variations in the isotopic composition of coals burned by the plants. The geographic pattern in ??34S for sites farther to the north in Wyoming and Montana was much less distinct, perhaps rflecting the paucity of major point sources of SO2 in the northern part of the network.

An experimental MOSFET approach to characterize (192)Ir HDR source anisotropy.

PubMed

Toye, W C; Das, K R; Todd, S P; Kenny, M B; Franich, R D; Johnston, P N

2007-09-07

The dose anisotropy around a (192)Ir HDR source in a water phantom has been measured using MOSFETs as relative dosimeters. In addition, modeling using the EGSnrc code has been performed to provide a complete dose distribution consistent with the MOSFET measurements. Doses around the Nucletron 'classic' (192)Ir HDR source were measured for a range of radial distances from 5 to 30 mm within a 40 x 30 x 30 cm(3) water phantom, using a TN-RD-50 MOSFET dosimetry system with an active area of 0.2 mm by 0.2 mm. For each successive measurement a linear stepper capable of movement in intervals of 0.0125 mm re-positioned the MOSFET at the required radial distance, while a rotational stepper enabled angular displacement of the source at intervals of 0.9 degrees . The source-dosimeter arrangement within the water phantom was modeled using the standardized cylindrical geometry of the DOSRZnrc user code. In general, the measured relative anisotropy at each radial distance from 5 mm to 30 mm is in good agreement with the EGSnrc simulations, benchmark Monte Carlo simulation and TLD measurements where they exist. The experimental approach employing a MOSFET detection system of small size, high spatial resolution and fast read out capability allowed a practical approach to the determination of dose anisotropy around a HDR source.

Experimental evaluation of the performance of pulsed two-color laser-ranging systems

NASA Technical Reports Server (NTRS)

Im, Kwaifong E.; Gardner, Chester S.; Abshire, James B.; Mcgarry, Jan F.

1987-01-01

Two-color laser-ranging systems can be used to estimate the atmospheric delay by measuring the difference in propagation times between two optical pulses transmitted at different wavelengths. This paper describes horizontal-path ranging experiments that were conducted using flat diffuse targets and cube-corner reflector arrays. Measurements of the timing accuracy of the cross-correlation estimator, atmospheric delay, received pulse shapes, and signal power spectra are presented. The results are in general agreement with theory and indicate that target speckle can be the dominant noise source when the target is small and is located far from the ranging system or when the target consists of a small number of cube-corner reflectors.

Multi-keV X-ray area source intensity at SGII laser facility

NASA Astrophysics Data System (ADS)

Wang, Rui-rong; An, Hong-hai; Xie, Zhi-yong; Wang, Wei

2018-05-01

Experiments for investigating the feasibility of multi-keV backlighters for several different metallic foil targets were performed at the Shenguang II (SGII) laser facility in China. Emission spectra in the energy range of 1.65-7.0 keV were measured with an elliptically bent crystal spectrometer, and the X-ray source size was measured with a pinhole camera. The X-ray intensity near 4.75 keV and the X-ray source size for titanium targets at different laser intensity irradiances were studied. By adjusting the total laser energy at a fixed focal spot size, laser intensity in the range of 1.5-5.0 × 1015 W/cm2, was achieved. The results show that the line emission intensity near 4.75 keV and the X-ray source size are dependent on the laser intensity and increase as the laser intensity increases. However, an observed "peak" in the X-ray intensity near 4.75 keV occurs at an irradiance of 4.0 × 1015 W/cm2. For the employed experimental conditions, it was confirmed that the laser intensity could play a significant role in the development of an efficient multi-keV X-ray source. The experimental results for titanium indicate that the production of a large (˜350 μm in diameter) intense backlighter source of multi-keV X-rays is feasible at the SGII facility.

A Source-based Measurement Database for Occupational Exposure Assessment of Electromagnetic Fields in the INTEROCC Study: A Literature Review Approach

PubMed Central

Vila, Javier; Bowman, Joseph D.; Richardson, Lesley; Kincl, Laurel; Conover, Dave L.; McLean, Dave; Mann, Simon; Vecchia, Paolo; van Tongeren, Martie; Cardis, Elisabeth

2016-01-01

Introduction: To date, occupational exposure assessment of electromagnetic fields (EMF) has relied on occupation-based measurements and exposure estimates. However, misclassification due to between-worker variability remains an unsolved challenge. A source-based approach, supported by detailed subject data on determinants of exposure, may allow for a more individualized exposure assessment. Detailed information on the use of occupational sources of exposure to EMF was collected as part of the INTERPHONE-INTEROCC study. To support a source-based exposure assessment effort within this study, this work aimed to construct a measurement database for the occupational sources of EMF exposure identified, assembling available measurements from the scientific literature. Methods: First, a comprehensive literature search was performed for published and unpublished documents containing exposure measurements for the EMF sources identified, a priori as well as from answers of study subjects. Then, the measurements identified were assessed for quality and relevance to the study objectives. Finally, the measurements selected and complementary information were compiled into an Occupational Exposure Measurement Database (OEMD). Results: Currently, the OEMD contains 1624 sets of measurements (>3000 entries) for 285 sources of EMF exposure, organized by frequency band (0 Hz to 300 GHz) and dosimetry type. Ninety-five documents were selected from the literature (almost 35% of them are unpublished technical reports), containing measurements which were considered informative and valid for our purpose. Measurement data and complementary information collected from these documents came from 16 different countries and cover the time period between 1974 and 2013. Conclusion: We have constructed a database with measurements and complementary information for the most common sources of exposure to EMF in the workplace, based on the responses to the INTERPHONE-INTEROCC study questionnaire. This database covers the entire EMF frequency range and represents the most comprehensive resource of information on occupational EMF exposure. It is available at www.crealradiation.com/index.php/en/databases. PMID:26493616

UV scale calibration transfer from an improved pyroelectric detector standard to field UV-A meters and 365 nm excitation sources

NASA Astrophysics Data System (ADS)

Eppeldauer, G. P.; Podobedov, V. B.; Cooksey, C. C.

2017-05-01

Calibration of the emitted radiation from UV sources peaking at 365 nm, is necessary to perform the ASTM required 1 mW/cm2 minimum irradiance in certain military material (ships, airplanes etc) tests. These UV "black lights" are applied for crack-recognition using fluorescent liquid penetrant inspection. At present, these nondestructive tests are performed using Hg-lamps. Lack of a proper standard and the different spectral responsivities of the available UV meters cause significant measurement errors even if the same UV-365 source is measured. A pyroelectric radiometer standard with spectrally flat (constant) response in the UV-VIS range has been developed to solve the problem. The response curve of this standard determined from spectral reflectance measurement, is converted into spectral irradiance responsivity with <0.5% (k=2) uncertainty as a result of using an absolute tie point from a Si-trap detector traceable to the primary standard cryogenic radiometer. The flat pyroelectric radiometer standard can be used to perform uniform integrated irradiance measurements from all kinds of UV sources (with different peaks and distributions) without using any source standard. Using this broadband calibration method, yearly spectral calibrations for the reference UV (LED) sources and irradiance meters is not needed. Field UV sources and meters can be calibrated against the pyroelectric radiometer standard for broadband (integrated) irradiance and integrated responsivity. Using the broadband measurement procedure, the UV measurements give uniform results with significantly decreased uncertainties.

Upgrades to improve the usability, reliability, and spectral range of the MST Thomson scattering diagnostic

NASA Astrophysics Data System (ADS)

Kubala, S. Z.; Borchardt, M. T.; Den Hartog, D. J.; Holly, D. J.; Jacobson, C. M.; Morton, L. A.; Young, W. C.

2016-11-01

The Thomson scattering diagnostic on MST records both equilibrium and fluctuating electron temperature with a range capability of 10 eV-5 keV. Standard operation with two modified commercial Nd:YAG lasers allows measurements at rates of 1 kHz-25 kHz. Several subsystems of the diagnostic are being improved. The power supplies for the avalanche photodiode detectors (APDs) that record the scattered light are being replaced to improve usability, reliability, and maintainability. Each of the 144 APDs will have an individual rack mounted switching supply, with bias voltage adjustable to match the APD. Long-wavelength filters (1140 nm center, 80 nm bandwidth) have been added to the polychromators to improve capability to resolve non-Maxwellian distributions and to enable directed electron flow measurements. A supercontinuum (SC) pulsed white light source has replaced the tungsten halogen lamp previously used for spectral calibration of the polychromators. The SC source combines substantial brightness produced in nanosecond pulses with a spectrum that covers the entire range of the polychromators.

Upgrades to improve the usability, reliability, and spectral range of the MST Thomson scattering diagnostic.

PubMed

Kubala, S Z; Borchardt, M T; Den Hartog, D J; Holly, D J; Jacobson, C M; Morton, L A; Young, W C

2016-11-01

The Thomson scattering diagnostic on MST records both equilibrium and fluctuating electron temperature with a range capability of 10 eV-5 keV. Standard operation with two modified commercial Nd:YAG lasers allows measurements at rates of 1 kHz-25 kHz. Several subsystems of the diagnostic are being improved. The power supplies for the avalanche photodiode detectors (APDs) that record the scattered light are being replaced to improve usability, reliability, and maintainability. Each of the 144 APDs will have an individual rack mounted switching supply, with bias voltage adjustable to match the APD. Long-wavelength filters (1140 nm center, 80 nm bandwidth) have been added to the polychromators to improve capability to resolve non-Maxwellian distributions and to enable directed electron flow measurements. A supercontinuum (SC) pulsed white light source has replaced the tungsten halogen lamp previously used for spectral calibration of the polychromators. The SC source combines substantial brightness produced in nanosecond pulses with a spectrum that covers the entire range of the polychromators.

Reliability of Monte Carlo simulations in modeling neutron yields from a shielded fission source

NASA Astrophysics Data System (ADS)

McArthur, Matthew S.; Rees, Lawrence B.; Czirr, J. Bart

2016-08-01

Using the combination of a neutron-sensitive 6Li glass scintillator detector with a neutron-insensitive 7Li glass scintillator detector, we are able to make an accurate measurement of the capture rate of fission neutrons on 6Li. We used this detector with a 252Cf neutron source to measure the effects of both non-borated polyethylene and 5% borated polyethylene shielding on detection rates over a range of shielding thicknesses. Both of these measurements were compared with MCNP calculations to determine how well the calculations reproduced the measurements. When the source is highly shielded, the number of interactions experienced by each neutron prior to arriving at the detector is large, so it is important to compare Monte Carlo modeling with actual experimental measurements. MCNP reproduces the data fairly well, but it does generally underestimate detector efficiency both with and without polyethylene shielding. For non-borated polyethylene it underestimates the measured value by an average of 8%. This increases to an average of 11% for borated polyethylene.

Characterization of near-terahertz complementary metal-oxide semiconductor circuits using a Fourier-transform interferometer

DOE PAGES

Arenas, D. J.; Shim, Dongha; Koukis, D. I.; ...

2011-10-24

Optical methods for measuring of the emission spectra of oscillator circuits operating in the 400-600 GHz range are described. The emitted power from patch antennas included in the circuits is measured by placing the circuit in the source chamber of a Fourier-transform interferometric spectrometer. The results show that this optical technique is useful for measuring circuits pushing the frontier in operating frequency. The technique also allows the characterization of the circuit by measuring the power radiated in the fundamental and in the harmonics. This capability is useful for oscillator architectures designed to cancel the fundamental and use higher harmonics. Themore » radiated power was measured using two techniques: direct measurement of the power by placing the device in front of a bolometer of known responsivity, and by comparison to the estimated power from blackbody sources. The latter technique showed that these circuits have higher emission than blackbody sources at the operating frequencies, and, therefore, offer potential spectroscopy applications.« less

New techniques in neutron data measurements above 30 MeV

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

Lisowski, P.W.; Haight, R.C.

1991-01-01

Recent developments in experimental facilities have enabled new techniques for measurements of neutron interactions above 30 MeV. Foremost is the development of both monoenergetic and continuous neutron sources using accelerators in the medium energy region between 100 and 800 MeV. Measurements of the reaction products have been advanced by the continuous improvement in detector systems, electronics and computers. Corresponding developments in particle transport codes and in the theory of nuclear reactions at these energies have allowed more precise design of neutron sources, experimental shielding and detector response. As a result of these improvements, many new measurements are possible and themore » data base in this energy range is expanding quickly.« less

Measuring Relativistic effects in the field of the Earth with Laser Ranged Satellites and the LARASE research program

NASA Astrophysics Data System (ADS)

Lucchesi, David; Anselmo, Luciano; Bassan, Massimo; Magnafico, Carmelo; Pardini, Carmen; Peron, Roberto; Pucacco, Giuseppe; Stanga, Ruggero; Visco, Massimo

2017-04-01

The main goal of the LARASE (LAser RAnged Satellites Experiment) research program is to obtain refined tests of Einstein's theory of General Relativity (GR) by means of very precise measurements of the round-trip time among a number of ground stations of the International Laser Ranging Service (ILRS) network and a set of geodetic satellites. These measurements are guaranteed by means of the powerful and precise Satellite Laser Ranging (SLR) technique. In particular, a big effort of LARASE is dedicated to improve the dynamical models of the LAGEOS, LAGEOS II and LARES satellites, with the objective to obtain a more precise and accurate determination of their orbit. These activities contribute to reach a final error budget that should be robust and reliable in the evaluation of the main systematic errors sources that come to play a major role in masking the relativistic precession on the orbit of these laser-ranged satellites. These error sources may be of gravitational and non-gravitational origin. It is important to stress that a more accurate and precise orbit determination, based on more reliable dynamical models, represents a fundamental prerequisite in order to reach a sub-mm precision in the root-mean-square of the SLR range residuals and, consequently, to gather benefits in the fields of geophysics and space geodesy, such as stations coordinates knowledge, geocenter determination and the realization of the Earth's reference frame. The results reached over the last year will be presented in terms of the improvements achieved in the dynamical model, in the orbit determination and, finally, in the measurement of the relativistic precessions that act on the orbit of the satellites considered.

Fire Source Localization Based on Distributed Temperature Sensing by a Dual-Line Optical Fiber System.

PubMed

Sun, Miao; Tang, Yuquan; Yang, Shuang; Li, Jun; Sigrist, Markus W; Dong, Fengzhong

2016-06-06

We propose a method for localizing a fire source using an optical fiber distributed temperature sensor system. A section of two parallel optical fibers employed as the sensing element is installed near the ceiling of a closed room in which the fire source is located. By measuring the temperature of hot air flows, the problem of three-dimensional fire source localization is transformed to two dimensions. The method of the source location is verified with experiments using burning alcohol as fire source, and it is demonstrated that the method represents a robust and reliable technique for localizing a fire source also for long sensing ranges.

[Features of control of electromagnetic radiation emitted by personal computers].

PubMed

Pal'tsev, Iu P; Buzov, A L; Kol'chugin, Iu I

1996-01-01

Measurements of PC electromagnetic irradiation show that the main sources are PC blocks emitting the waves of certain frequencies. Use of wide-range detectors measuring field intensity in assessment of PC electromagnetic irradiation gives unreliable results. More precise measurements by selective devices are required. Thus, it is expedient to introduce a term "spectral density of field intensity" and its maximal allowable level. In this case a frequency spectrum of PC electromagnetic irradiation is divided into 4 ranges, one of which is subjected to calculation of field intensity for each harmonic frequency, and others undergo assessment of spectral density of field intensity.

Transport of Aerosols: Regional and Global Implications for Climate, Weather, and Air Quality

NASA Technical Reports Server (NTRS)

Chin, Mian; Diehl, Thomas; Yu, Hongbin; Bian, Huisheng; Remer, Lorraine; Kahn, Ralph

2008-01-01

Long-range transport of atmospheric aerosols can have a significant impact on global climate, regional weather, and local air quality. In this study, we use a global model GOCART together with satellite data and ground-based measurements to assess the emission and transport of pollution, dust, biomass burning, and volcanic aerosols and their implications. In particular, we will show the impact of emissions and long-range transport of aerosols from major pollution and dust source regions to (1) the surface air quality, (2) the atmospheric heating rates, and (3) surface radiation change near the source and downwind regions.

S-193 scatterometer transfer function analysis for data processing

NASA Technical Reports Server (NTRS)

Johnson, L.

1974-01-01

A mathematical model for converting raw data measurements of the S-193 scatterometer into processed values of radar scattering coefficient is presented. The argument is based on an approximation derived from the Radar Equation and actual operating principles of the S-193 Scatterometer hardware. Possible error sources are inaccuracies in transmitted wavelength, range, antenna illumination integrals, and the instrument itself. The dominant source of error in the calculation of scattering coefficent is accuracy of the range. All other ractors with the possible exception of illumination integral are not considered to cause significant error in the calculation of scattering coefficient.

Sediment dynamics and sources in a grazed hardwood rangeland watershed

Treesearch

Melvin R. George; Neil K. McDougald; Kenneth W. Tate; Royce Larsen

2002-01-01

From 1994 to 1998 we documented sediment transport dynamics and sources in a 137 ha grazed hardwood rangeland watershed on granitic soils at the San Joaquin Experimental Range in Madera County. Sediment transport for this watershed was determined by measuring total suspended solids, bedload and flow at an H-flume installed in 1994. Sediment movement as bedload is the...

A fully automated temperature-dependent resistance measurement setup using van der Pauw method

NASA Astrophysics Data System (ADS)

Pandey, Shivendra Kumar; Manivannan, Anbarasu

2018-03-01

The van der Pauw (VDP) method is widely used to identify the resistance of planar homogeneous samples with four contacts placed on its periphery. We have developed a fully automated thin film resistance measurement setup using the VDP method with the capability of precisely measuring a wide range of thin film resistances from few mΩ up to 10 GΩ under controlled temperatures from room-temperature up to 600 °C. The setup utilizes a robust, custom-designed switching network board (SNB) for measuring current-voltage characteristics automatically at four different source-measure configurations based on the VDP method. Moreover, SNB is connected with low noise shielded coaxial cables that reduce the effect of leakage current as well as the capacitance in the circuit thereby enhancing the accuracy of measurement. In order to enable precise and accurate resistance measurement of the sample, wide range of sourcing currents/voltages are pre-determined with the capability of auto-tuning for ˜12 orders of variation in the resistances. Furthermore, the setup has been calibrated with standard samples and also employed to investigate temperature dependent resistance (few Ω-10 GΩ) measurements for various chalcogenide based phase change thin films (Ge2Sb2Te5, Ag5In5Sb60Te30, and In3SbTe2). This setup would be highly helpful for measurement of temperature-dependent resistance of wide range of materials, i.e., metals, semiconductors, and insulators illuminating information about structural change upon temperature as reflected by change in resistances, which are useful for numerous applications.

Ultra-high Temperature Emittance Measurements for Space and Missile Applications

NASA Technical Reports Server (NTRS)

Rogers, Jan; Crandall, David

2009-01-01

Advanced modeling and design efforts for many aerospace components require high temperature emittance data. Applications requiring emittance data include propulsion systems, radiators, aeroshells, heatshields/thermal protection systems, and leading edge surfaces. The objective of this work is to provide emittance data at ultra-high temperatures. MSFC has a new instrument for the measurement of emittance at ultra-high temperatures, the Ultra-High Temperature Emissometer System (Ultra-HITEMS). AZ Technology Inc. developed the instrument, designed to provide emittance measurements over the temperature range 700-3500K. The Ultra-HITEMS instrument measures the emittance of samples, heated by lasers, in vacuum, using a blackbody source and a Fourier Transform Spectrometer. Detectors in a Nicolet 6700 FT-IR spectrometer measure emittance over the spectral range of 0.4-25 microns. Emitted energy from the specimen and output from a Mikron M390S blackbody source at the same temperature with matched collection geometry are measured. Integrating emittance over the spectral range yields the total emittance. The ratio provides a direct measure of total hemispherical emittance. Samples are heated using lasers. Optical pyrometry provides temperature data. Optical filters prevent interference from the heating lasers. Data for Inconel 718 show excellent agreement with results from literature and ASTM 835. Measurements taken from levitated spherical specimens provide total hemispherical emittance data; measurements taken from flat specimens mounted in the chamber provide near-normal emittance data. Data from selected characterization studies will be presented. The Ultra-HITEMS technique could advance space and missile technologies by advancing the knowledge base and the technology readiness level for ultra-high temperature materials.

Tracing carbonaceous sources by using particulate carbon and sulfate in precipitation in Calgary, Alberta Canada

NASA Astrophysics Data System (ADS)

Ge, C.; Stenhouse, K. J.; Du, K.; Xing, Z.; Norman, A. L.

2016-12-01

Carbonaceous matter is often the dominant contributor to Particulate Matter (PM) which has a significant influence on climate, air quality and human health. The measurement of particulate carbon in rainfall in Calgary, Alberta has not been studied. This study reports the sulfate and the first concentrations of particulate carbon (PC) in rainfall in Calgary. It traces seasonal carbonaceous sources for the purpose of understanding sources for air quality control. Precipitation samples are collected twice a day at the University of Calgary. Thermo-optical methods are used to analyze concentrations of PC, including elemental carbon (EC), primary organic carbon (POC) and secondary organic carbon (SOC). Sulfate concentrations are measured using ion chromatography. In this study, sources from long range transport and local emissions are examined. We emphasized the apportionment of OC/EC in oil and gas emissions and diurnal variations in transportation emissions. Weekly average data for dry deposition were calculated to estimate the scavenging ratio of EC/POC/SOC and ions in precipitation. The results of this study will be presented with an emphasis on the relationship of carbonaceous material and sulfate. A range of apportionment methods have been applied to examine limitations in quantifying SOC in fall.

Nano-Electromechanical Systems: Displacement Detection and the Mechanical Single Electron Shuttle

NASA Astrophysics Data System (ADS)

Blick, R. H.; Beil, F. W.; Höhberger, E.; Erbe, A.; Weiss, C.

For an introduction to nano-electromechanical systems we present measurements on nanomechanical resonators operating in the radio frequency range. We discuss in detail two different schemes of displacement detection for mechanical resonators, namely conventional reflection measurements of a probing signal and direct detection by capacitive coupling via a gate electrode. For capacitive detection we employ an on-chip preamplifier, which enables direct measurements of the resonator's disp lacement. We observe that the mechanical quality factor of the resonator depends on the detection technique applied, which is verified in model calculations and report on the detection of sub-harmonics. In the second part we extend our investigations to include transport of single electrons through an electron island on the tip of a nanomachined mechanical pendulum. The pendulum is operated by applying a modulating electromagnetic field in the range of 1 - 200 MHz, leading to mechanical oscillations between two laterally integrated source and drain contacts. Forming tunneling barriers the metallic tip shuttles single electrons from source to drain. The resulting tunneling current shows distinct features corresponding to the discrete mechanical eigenfrequencies of the pendulum. We report on measurements covering the temperature range from 300 K down to 4.2 K. The transport properties of the device are compared in detail to model calculations based on a Master-equation approach.

Genetic variation of piperidine alkaloids in Pinus ponderosa: a common garden study.

PubMed

Gerson, Elizabeth A; Kelsey, Rick G; St Clair, J Bradley

2009-02-01

Previous measurements of conifer alkaloids have revealed significant variation attributable to many sources, environmental and genetic. The present study takes a complementary and intensive, common garden approach to examine genetic variation in Pinus ponderosa var. ponderosa alkaloid production. Additionally, this study investigates the potential trade-off between seedling growth and alkaloid production, and associations between topographic/climatic variables and alkaloid production. Piperidine alkaloids were quantified in foliage of 501 nursery seedlings grown from seed sources in west-central Washington, Oregon and California, roughly covering the western half of the native range of ponderosa pine. A nested mixed model was used to test differences among broad-scale regions and among families within regions. Alkaloid concentrations were regressed on seedling growth measurements to test metabolite allocation theory. Likewise, climate characteristics at the seed sources were also considered as explanatory variables. Quantitative variation from seedling to seedling was high, and regional variation exceeded variation among families. Regions along the western margin of the species range exhibited the highest alkaloid concentrations, while those further east had relatively low alkaloid levels. Qualitative variation in alkaloid profiles was low. All measures of seedling growth related negatively to alkaloid concentrations on a natural log scale; however, coefficients of determination were low. At best, annual height increment explained 19.4 % of the variation in ln(total alkaloids). Among the climate variables, temperature range showed a negative, linear association that explained 41.8 % of the variation. Given the wide geographic scope of the seed sources and the uniformity of resources in the seedlings' environment, observed differences in alkaloid concentrations are evidence for genetic regulation of alkaloid secondary metabolism in ponderosa pine. The theoretical trade-off with seedling growth appeared to be real, however slight. The climate variables provided little evidence for adaptive alkaloid variation, especially within regions.

Range compensation for backscattering measurements in the difference-frequency nearfield of a parametric sonar.

PubMed

Foote, Kenneth G

2012-05-01

Measurement of acoustic backscattering properties of targets requires removal of the range dependence of echoes. This process is called range compensation. For conventional sonars making measurements in the transducer farfield, the compensation removes effects of geometrical spreading and absorption. For parametric sonars consisting of a parametric acoustic transmitter and a conventional-sonar receiver, two additional range dependences require compensation when making measurements in the nonlinearly generated difference-frequency nearfield: an apparently increasing source level and a changing beamwidth. General expressions are derived for range compensation functions in the difference-frequency nearfield of parametric sonars. These are evaluated numerically for a parametric sonar whose difference-frequency band, effectively 1-6 kHz, is being used to observe Atlantic herring (Clupea harengus) in situ. Range compensation functions for this sonar are compared with corresponding functions for conventional sonars for the cases of single and multiple scatterers. Dependences of these range compensation functions on the parametric sonar transducer shape, size, acoustic power density, and hydrography are investigated. Parametric range compensation functions, when applied with calibration data, will enable difference-frequency echoes to be expressed in physical units of volume backscattering, and backscattering spectra, including fish-swimbladder-resonances, to be analyzed.

Atmospheric simulator and calibration system for remote sensing radiometers

NASA Technical Reports Server (NTRS)

Holland, J. A.

1983-01-01

A system for calibrating the MAPS (measurement of air pollution from satellites) instruments was developed. The design of the system provides a capability for simulating a broad range of radiant energy source temperatures and a broad range of atmospheric pressures, temperatures, and pollutant concentrations for a single slab atmosphere. The system design and the system operation are described.

Development of an apparatus for obtaining molecular beams in the energy range from 2 to 200 eV

NASA Technical Reports Server (NTRS)

Clapier, R.; Devienne, F. M.; Roustan, A.; Roustan, J. C.

1985-01-01

The formation and detection of molecular beams obtained by charge exchange from a low-energy ion source is discussed. Dispersion in energy of the ion source was measured and problems concerning detection of neutral beams were studied. Various methods were used, specifically secondary electron emissivity of a metallic surface and ionization of a gas target with a low ionization voltage. The intensities of neutral beams as low as 10 eV are measured by a tubular electron multiplier and a lock-in amplifier.

Primary calibrations of radionuclide solutions and sources for the EML quality assessment program

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

Fisenne, I.M.

1993-12-31

The quality assurance procedures established for the operation of the U.S. Department of Energy`s Environmental Measurements Laboratory (DOE-EML`s) Quality Assessment Program (QAP) are essentially the same as those that are in effect for any EML program involving radiometric measurements. All these programs have at their core the use of radionuclide standards for their instrument calibration. This paper focuses on EML`s approach to the acquisition, calibration and application of a wide range of radionuclide sources that are required to meet its programmatic needs.

Two-Step Calibration of a Multiwavelength Pyrometer for High Temperature Measurement Using a Quartz Lamp

NASA Technical Reports Server (NTRS)

Ng, Daniel

2001-01-01

There is no theoretical upper temperature limit for pyrometer application in temperature measurements. NASA Glenn's multiwavelength pyrometer can make measurements over wide temperature ranges. However, the radiation spectral response of the pyrometer's detector must be calibrated before any temperature measurement is attempted, and it is recommended that calibration be done at temperatures close to those for which measurements will be made. Calibration is a determination of the constants of proportionality at all wavelengths between the detector's output (voltage) and its input signals (usually from a blackbody radiation source) in order to convert detector output into radiation intensity. To measure high temperatures, the detectors are chosen to be sensitive in the spectral range from 0.4 to 2.5 micrometers. A blackbody furnace equilibrated at around 1000 C is often used for this calibration. Though the detector may respond sensitively to short wavelengths radiation, a blackbody furnace at 1000 C emits only feebly at very short wavelengths. As a consequence, the calibration constants that result may not be the most accurate. For pyrometry calibration, a radiation source emitting strongly at the short wavelengths is preferred. We have chosen a quartz halogen lamp for this purpose.

Lenstronomy: Multi-purpose gravitational lens modeling software package

NASA Astrophysics Data System (ADS)

Birrer, Simon; Amara, Adam

2018-04-01

Lenstronomy is a multi-purpose open-source gravitational lens modeling python package. Lenstronomy reconstructs the lens mass and surface brightness distributions of strong lensing systems using forward modelling and supports a wide range of analytic lens and light models in arbitrary combination. The software is also able to reconstruct complex extended sources as well as point sources. Lenstronomy is flexible and numerically accurate, with a clear user interface that could be deployed across different platforms. Lenstronomy has been used to derive constraints on dark matter properties in strong lenses, measure the expansion history of the universe with time-delay cosmography, measure cosmic shear with Einstein rings, and decompose quasar and host galaxy light.

Narrow Angle Wide Spectral Range Radiometer Design FEANICS/REEFS Radiometer Design Report

NASA Technical Reports Server (NTRS)

Camperchioli, William

2005-01-01

A critical measurement for the Radiative Enhancement Effects on Flame Spread (REEFS) microgravity combustion experiment is the net radiative flux emitted from the gases and from the solid fuel bed. These quantities are measured using a set of narrow angle, wide spectral range radiometers. The radiometers are required to have an angular field of view of 1.2 degrees and measure over the spectral range of 0.6 to 30 microns, which presents a challenging design effort. This report details the design of this radiometer system including field of view, radiometer response, radiometric calculations, temperature effects, error sources, baffling and amplifiers. This report presents some radiometer specific data but does not present any REEFS experiment data.

Using a Divided Bar Apparatus to Measure Thermal Conductivity of Samples of Odd Sizes and Shapes

NASA Astrophysics Data System (ADS)

Crowell, J. "; Gosnold, W. D.

2012-12-01

Standard procedure for measuring thermal conductivity using a divided bar apparatus requires a sample that has the same surface dimensions as the heat sink/source surface in the divided bar. Heat flow is assumed to be constant throughout the column and thermal conductivity (K) is determined by measuring temperatures (T) across the sample and across standard layers and using the basic relationship Ksample=(Kstandard*(ΔT1+ΔT2)/2)/(ΔTsample). Sometimes samples are not large enough or of correct proportions to match the surface of the heat sink/source, however using the equations presented here the thermal conductivity of these samples can still be measured with a divided bar. Measurements were done on the UND Geothermal Laboratories stationary divided bar apparatus (SDB). This SDB has been designed to mimic many in-situ conditions, with a temperature range of -20C to 150C and a pressure range of 0 to 10,000 psi for samples with parallel surfaces and 0 to 3000 psi for samples with non-parallel surfaces. The heat sink/source surfaces are copper disks and have a surface area of 1,772 mm2 (2.74 in2). Layers of polycarbonate 6 mm thick with the same surface area as the copper disks are located in the heat sink and in the heat source as standards. For this study, all samples were prepared from a single piece of 4 inch limestone core. Thermal conductivities were measured for each sample as it was cut successively smaller. The above equation was adjusted to include the thicknesses (Th) of the samples and the standards and the surface areas (A) of the heat sink/source and of the sample Ksample=(Kstandard*Astandard*Thsample*(ΔT1+ΔT3))/(ΔTsample*Asample*2*Thstandard). Measuring the thermal conductivity of samples of multiple sizes, shapes, and thicknesses gave consistent values for samples with surfaces as small as 50% of the heat sink/source surface, regardless of the shape of the sample. Measuring samples with surfaces smaller than 50% of the heat sink/source surface resulted in thermal conductivity values which were too high. The cause of the error with the smaller samples is being examined as is the relationship between the amount of error in the thermal conductivity and the difference in surface areas. As more measurements are made an equation to mathematically correct for the error is being developed on in case a way to physically correct the problem cannot be determined.

A thermosphere composition measurement using a quadrupole mass spectrometer with a side energy focussing quasi-open ion source

NASA Technical Reports Server (NTRS)

Niemann, H. B.; Spencer, N. W.; Schmitt, G. A.

1971-01-01

The atomic oxygen concentration in the altitude range 130 to 240 km was determined through the use of a quadrupole spectrometer with a strongly focussing ion source. The instrument is used in the Thermosphere Probe in a manner that greatly increases the proportion of measured oxygen ions that have not experienced a surface collision and permits quantitative evaluation of surface recombination and thermalization effects which inevitably enter all spectrometer determinations. The data obtained strengthen the concept that consideration of surface effects is significant in quantifying spectrometer measurements of reactive gases, and tend to be in agreement with von Zahn's recent results.

Space-Borne Laser Altimeter Geolocation Error Analysis

NASA Astrophysics Data System (ADS)

Wang, Y.; Fang, J.; Ai, Y.

2018-05-01

This paper reviews the development of space-borne laser altimetry technology over the past 40 years. Taking the ICESAT satellite as an example, a rigorous space-borne laser altimeter geolocation model is studied, and an error propagation equation is derived. The influence of the main error sources, such as the platform positioning error, attitude measurement error, pointing angle measurement error and range measurement error, on the geolocation accuracy of the laser spot are analysed by simulated experiments. The reasons for the different influences on geolocation accuracy in different directions are discussed, and to satisfy the accuracy of the laser control point, a design index for each error source is put forward.

Chameleon vector bosons

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

Nelson, Ann E.; Instituto de Fisica Teorica UAM/CSIC, Facultad de Ciencias, C-XVI Universidad Autonoma de Madrid Cantoblanco, Madrid 28049; Walsh, Jonathan

2008-05-01

We show that for a force mediated by a vector particle coupled to a conserved U(1) charge, the apparent range and strength can depend on the size and density of the source, and the proximity to other sources. This chameleon effect is due to screening from a light charged scalar. Such screening can weaken astrophysical constraints on new gauge bosons. As an example we consider the constraints on chameleonic gauged B-L. We show that although Casimir measurements greatly constrain any B-L force much stronger than gravity with range longer than 0.1 {mu}m, there remains an experimental window for a long-rangemore » chameleonic B-L force. Such a force could be much stronger than gravity, and long or infinite range in vacuum, but have an effective range near the surface of the earth which is less than a micron.« less

Geodetic positioning using a global positioning system of satellites

NASA Technical Reports Server (NTRS)

Fell, P. J.

1980-01-01

Geodetic positioning using range, integrated Doppler, and interferometric observations from a constellation of twenty-four Global Positioning System satellites is analyzed. A summary of the proposals for geodetic positioning and baseline determination is given which includes a description of measurement techniques and comments on rank deficiency and error sources. An analysis of variance comparison of range, Doppler, and interferometric time delay to determine their relative geometric strength for baseline determination is included. An analytic examination to the effect of a priori constraints on positioning using simultaneous observations from two stations is presented. Dynamic point positioning and baseline determination using range and Doppler is examined in detail. Models for the error sources influencing dynamic positioning are developed. Included is a discussion of atomic clock stability, and range and Doppler observation error statistics based on random correlated atomic clock error are derived.

Applications of the Integrated High-Performance CMOS Image Sensor to Range Finders — from Optical Triangulation to the Automotive Field

PubMed Central

Wu, Jih-Huah; Pen, Cheng-Chung; Jiang, Joe-Air

2008-01-01

With their significant features, the applications of complementary metal-oxide semiconductor (CMOS) image sensors covers a very extensive range, from industrial automation to traffic applications such as aiming systems, blind guidance, active/passive range finders, etc. In this paper CMOS image sensor-based active and passive range finders are presented. The measurement scheme of the proposed active/passive range finders is based on a simple triangulation method. The designed range finders chiefly consist of a CMOS image sensor and some light sources such as lasers or LEDs. The implementation cost of our range finders is quite low. Image processing software to adjust the exposure time (ET) of the CMOS image sensor to enhance the performance of triangulation-based range finders was also developed. An extensive series of experiments were conducted to evaluate the performance of the designed range finders. From the experimental results, the distance measurement resolutions achieved by the active range finder and the passive range finder can be better than 0.6% and 0.25% within the measurement ranges of 1 to 8 m and 5 to 45 m, respectively. Feasibility tests on applications of the developed CMOS image sensor-based range finders to the automotive field were also conducted. The experimental results demonstrated that our range finders are well-suited for distance measurements in this field. PMID:27879789

Thermal Interface Evaluation of Heat Transfer from a Pumped Loop to Titanium-Water Thermosyphons

NASA Technical Reports Server (NTRS)

Jaworske, Donald A.; Sanzi, James L.; Gibson, Marc A.; Sechkar, Edward A.

2009-01-01

Titanium-water thermosyphons are being considered for use in the heat rejection system for lunar outpost fission surface power. Key to their use is heat transfer between a closed loop heat source and the heat pipe evaporators. This work describes laboratory testing of several interfaces that were evaluated for their thermal performance characteristics, in the temperature range of 350 to 400 K, utilizing a water closed loop heat source and multiple thermosyphon evaporator geometries. A gas gap calorimeter was used to measure heat flow at steady state. Thermocouples in the closed loop heat source and on the evaporator were used to measure thermal conductance. The interfaces were in two generic categories, those immersed in the water closed loop heat source and those clamped to the water closed loop heat source with differing thermal conductive agents. In general, immersed evaporators showed better overall performance than their clamped counterparts. Selected clamped evaporator geometries offered promise.

On-chip low loss heralded source of pure single photons.

PubMed

Spring, Justin B; Salter, Patrick S; Metcalf, Benjamin J; Humphreys, Peter C; Moore, Merritt; Thomas-Peter, Nicholas; Barbieri, Marco; Jin, Xian-Min; Langford, Nathan K; Kolthammer, W Steven; Booth, Martin J; Walmsley, Ian A

2013-06-03

A key obstacle to the experimental realization of many photonic quantum-enhanced technologies is the lack of low-loss sources of single photons in pure quantum states. We demonstrate a promising solution: generation of heralded single photons in a silica photonic chip by spontaneous four-wave mixing. A heralding efficiency of 40%, corresponding to a preparation efficiency of 80% accounting for detector performance, is achieved due to efficient coupling of the low-loss source to optical fibers. A single photon purity of 0.86 is measured from the source number statistics without narrow spectral filtering, and confirmed by direct measurement of the joint spectral intensity. We calculate that similar high-heralded-purity output can be obtained from visible to telecom spectral regions using this approach. On-chip silica sources can have immediate application in a wide range of single-photon quantum optics applications which employ silica photonics.

Electrophysiological Source Imaging: A Noninvasive Window to Brain Dynamics.

PubMed

He, Bin; Sohrabpour, Abbas; Brown, Emery; Liu, Zhongming

2018-06-04

Brain activity and connectivity are distributed in the three-dimensional space and evolve in time. It is important to image brain dynamics with high spatial and temporal resolution. Electroencephalography (EEG) and magnetoencephalography (MEG) are noninvasive measurements associated with complex neural activations and interactions that encode brain functions. Electrophysiological source imaging estimates the underlying brain electrical sources from EEG and MEG measurements. It offers increasingly improved spatial resolution and intrinsically high temporal resolution for imaging large-scale brain activity and connectivity on a wide range of timescales. Integration of electrophysiological source imaging and functional magnetic resonance imaging could further enhance spatiotemporal resolution and specificity to an extent that is not attainable with either technique alone. We review methodological developments in electrophysiological source imaging over the past three decades and envision its future advancement into a powerful functional neuroimaging technology for basic and clinical neuroscience applications.

Resolving multiple propagation paths in time of flight range cameras using direct and global separation methods

NASA Astrophysics Data System (ADS)

Whyte, Refael; Streeter, Lee; Cree, Michael J.; Dorrington, Adrian A.

2015-11-01

Time of flight (ToF) range cameras illuminate the scene with an amplitude-modulated continuous wave light source and measure the returning modulation envelopes: phase and amplitude. The phase change of the modulation envelope encodes the distance travelled. This technology suffers from measurement errors caused by multiple propagation paths from the light source to the receiving pixel. The multiple paths can be represented as the summation of a direct return, which is the return from the shortest path length, and a global return, which includes all other returns. We develop the use of a sinusoidal pattern from which a closed form solution for the direct and global returns can be computed in nine frames with the constraint that the global return is a spatially lower frequency than the illuminated pattern. In a demonstration on a scene constructed to have strong multipath interference, we find the direct return is not significantly different from the ground truth in 33/136 pixels tested; where for the full-field measurement, it is significantly different for every pixel tested. The variance in the estimated direct phase and amplitude increases by a factor of eight compared with the standard time of flight range camera technique.

The development of effects-based air quality management regimes

NASA Astrophysics Data System (ADS)

Longhurst, J. W. S.; Irwin, J. G.; Chatterton, T. J.; Hayes, E. T.; Leksmono, N. S.; Symons, J. K.

This paper considers the evolution of attempts to control and manage air pollution, principally but not exclusively focussing upon the challenge of managing air pollution in urban environments. The development and implementation of a range of air pollution control measures are considered. Initially the measures implemented primarily addressed point sources, a small number of fuel types and a limited number of pollutants. The adequacy of such a source-control approach is assessed within the context of a changing and challenging air pollution climate. An assessment of air quality management in the United Kingdom over a 50-year timeframe exemplifies the range of issues and challenges in contemporary air quality management. The need for new approaches is explored and the development and implementation of an effects-based, risk management system for air quality regulation is evaluated.

Aureole radiance field about a source in a scattering-absorbing medium.

PubMed

Zachor, A S

1978-06-15

A technique is described for computing the aureole radiance field about a point source in a medium that absorbs and scatters according to an arbitrary phase function. When applied to an isotropic source in a homogenous medium, the method uses a double-integral transform which is evaluated recursively to obtain the aureole radiances contributed by successive scattering orders, as in the Neumann solution of the radiative transfer equation. The normalized total radiance field distribution and the variation of flux with field of view and range are given for three wavelengths in the uv and one in the visible, for a sea-level model atmosphere assumed to scatter according to a composite of the Rayleigh and modified Henyey-Greenstein phase functions. These results have application to the detection and measurement of uncollimated uv and visible sources at short ranges in the lower atmosphere.

ANS hard X-ray experiment development program. [emission from X-ray sources

NASA Technical Reports Server (NTRS)

Parsignault, D.; Gursky, H.; Frank, R.; Kubierschky, K.; Austin, G.; Paganetti, R.; Bawdekar, V.

1974-01-01

The hard X-ray (HXX) experiment is one of three experiments included in the Dutch Astronomical Netherlands Satellite, which was launched into orbit on 30 August 1974. The overall objective of the HXX experiment is the detailed study of the emission from known X-ray sources over the energy range 1.5-30keV. The instrument is capable of the following measurements: (1) spectral content over the full energy range with an energy resolution of approximately 20% and time resolution down to 4 seconds; (2) source time variability down to 4 milliseconds; (3) silicon emission lines at 1.86 and 2.00keV; (4) source location to a limit of one arc minute in ecliptic latitude; and (5) spatial structure with angular resolution of the arc minutes. Scientific aspects of experiment, engineering design and implementation of the experiment, and program history are included.

Collecting evidence from distributed sources to evaluate railway suicide and trespass prevention measures.

PubMed

Ryan, Brendan; Kallberg, Veli-Pekka; Rådbo, Helena; Havârneanu, Grigore M; Silla, Anne; Lukaschek, Karoline; Burkhardt, Jean-Marie; Bruyelle, Jean-Luc; El-Koursi, El-Miloudi; Beurskens, Eric; Hedqvist, Maria

2018-06-08

It can be difficult to select from available safety preventative measures, especially where there is limited evidence of effectiveness in different contexts. This paper describes application of a method to identify and evaluate wide-ranging preventative measures for rail suicide and trespass fatalities. Evidence from literature and industry sources was collated and reviewed in a two stage process to achieve consensus among experts on the likely effects of the measures and factors influencing their implementation. Multiple evaluation criteria were used to examine the measures from different perspectives. Fencing, awareness campaigns and different types of organisational initiatives were recommended for further testing. This is the first time evidence has been collected internationally across such a range of preventative measures. Commentary is provided on using this type of approach to select safety measures from a pool of prevention options, including how re-framing the scope of the exercise could identify alternative options for prevention. Practitioner summary. The findings give insight to how different measures work in different ways and how industry can consider this in strategic initiatives. The method could be used in future studies with different frames of reference (e.g. different timescales, level of ambition and safety context e.g. railway crossings or highway fatalities).

Deep Galex Observations of the Coma Cluster: Source Catalog and Galaxy Counts

NASA Technical Reports Server (NTRS)

Hammer, D.; Hornschemeier, A. E.; Mobasher, B.; Miller, N.; Smith, R.; Arnouts, S.; Milliard, B.; Jenkins, L.

2010-01-01

We present a source catalog from deep 26 ks GALEX observations of the Coma cluster in the far-UV (FUV; 1530 Angstroms) and near-UV (NUV; 2310 Angstroms) wavebands. The observed field is centered 0.9 deg. (1.6 Mpc) south-west of the Coma core, and has full optical photometric coverage by SDSS and spectroscopic coverage to r-21. The catalog consists of 9700 galaxies with GALEX and SDSS photometry, including 242 spectroscopically-confirmed Coma member galaxies that range from giant spirals and elliptical galaxies to dwarf irregular and early-type galaxies. The full multi-wavelength catalog (cluster plus background galaxies) is 80% complete to NUV=23 and FUV=23.5, and has a limiting depth at NUV=24.5 and FUV=25.0 which corresponds to a star formation rate of 10(exp -3) solar mass yr(sup -1) at the distance of Coma. The GALEX images presented here are very deep and include detections of many resolved cluster members superposed on a dense field of unresolved background galaxies. This required a two-fold approach to generating a source catalog: we used a Bayesian deblending algorithm to measure faint and compact sources (using SDSS coordinates as a position prior), and used the GALEX pipeline catalog for bright and/or extended objects. We performed simulations to assess the importance of systematic effects (e.g. object blends, source confusion, Eddington Bias) that influence source detection and photometry when using both methods. The Bayesian deblending method roughly doubles the number of source detections and provides reliable photometry to a few magnitudes deeper than the GALEX pipeline catalog. This method is also free from source confusion over the UV magnitude range studied here: conversely, we estimate that the GALEX pipeline catalogs are confusion limited at NUV approximately 23 and FUV approximately 24. We have measured the total UV galaxy counts using our catalog and report a 50% excess of counts across FUV=22-23.5 and NUV=21.5-23 relative to previous GALEX measurements, which is not attributed to cluster member galaxies. Our galaxy counts are a better match to deeper UV counts measured with HST.

Stochastic and Resolvable Gravitational Waves from Ultralight Bosons.

PubMed

Brito, Richard; Ghosh, Shrobana; Barausse, Enrico; Berti, Emanuele; Cardoso, Vitor; Dvorkin, Irina; Klein, Antoine; Pani, Paolo

2017-09-29

Ultralight scalar fields around spinning black holes can trigger superradiant instabilities, forming a long-lived bosonic condensate outside the horizon. We use numerical solutions of the perturbed field equations and astrophysical models of massive and stellar-mass black hole populations to compute, for the first time, the stochastic gravitational-wave background from these sources. In optimistic scenarios the background is observable by Advanced LIGO and LISA for field masses m_{s} in the range ∼[2×10^{-13},10^{-12}] and ∼5×[10^{-19},10^{-16}]  eV, respectively, and it can affect the detectability of resolvable sources. Our estimates suggest that an analysis of the stochastic background limits from LIGO O1 might already be used to marginally exclude axions with mass ∼10^{-12.5}  eV. Semicoherent searches with Advanced LIGO (LISA) should detect ∼15(5) to 200(40) resolvable sources for scalar field masses 3×10^{-13} (10^{-17})  eV. LISA measurements of massive BH spins could either rule out bosons in the range ∼[10^{-18},2×10^{-13}]  eV, or measure m_{s} with 10% accuracy in the range ∼[10^{-17},10^{-13}]  eV.

[Passive ranging of infrared target using oxygen A-band and Elsasser model].

PubMed

Li, Jin-Hua; Wang, Zhao-Ba; Wang Zhi

2014-09-01

Passive ranging method of short range and single band was developed based on target radiation and attenuation characteristic of oxygen spectrum absorption. The relation between transmittance of oxygen A band and range of measured target was analyzed. Radiation strength distribution of measured target can be obtained according to the distribution law of absorption coefficient with environmental parameters. Passive ranging mathematical model of short ranges was established using Elsasser model with Lorentz line shape based on the computational methods of band average transmittance and high-temperature gas radiation narrowband model. The range of measured object was obtained using transmittance fitting with test data calculation and theoretical model. Besides, ranging precision was corrected considering the influence of oxygen absorption with enviromental parameter. The ranging experiment platform was established. The source was a 10 watt black body, and a grating spectrometer with 17 cm(-1) resolution was used. In order to improve the light receiving efficiency, light input was collected with 23 mm calibre telescope. The test data was processed for different range in 200 m. The results show that the transmittance accuracy was better than 2.18% in short range compared to the test data with predicted value in the same conditions.

Cross section measurements at LANSCE for defense, science and applications

DOE PAGES

Nelson, Ronald O.; Schwengner, R.; Zuber, K.

2015-05-28

The Los Alamos Neutron Science Center (LANSCE) has three neutron sources that are used for nuclear science measurements. These sources are driven by an 800 MeV proton linear accelerator and cover an energy range from sub-thermal to hundreds of MeV. Research at the facilities is performed under the auspices of a US DOE user program under which research proposals are rated for merit by a program advisory committee and are scheduled based on merit and availability of beam time. A wide variety of instruments is operated at the neutron flight paths at LANSCE including neutron detector arrays, gamma-ray detector arrays,more » fission fragment detectors, and charged particle detectors. These instruments provide nuclear data for multiple uses that range from increasing knowledge in fundamental science to satisfying data needs for diverse applications such as nuclear energy, global security, and industrial applications. In addition, highlights of recent research related to cross sections measurements are presented, and future research initiatives are discussed.« less

The Pearson-Readhead Survey of Compact Extragalactic Radio Sources from Space. I. The Images

NASA Astrophysics Data System (ADS)

Lister, M. L.; Tingay, S. J.; Murphy, D. W.; Piner, B. G.; Jones, D. L.; Preston, R. A.

2001-06-01

We present images from a space-VLBI survey using the facilities of the VLBI Space Observatory Programme (VSOP), drawing our sample from the well-studied Pearson-Readhead survey of extragalactic radio sources. Our survey has taken advantage of long space-VLBI baselines and large arrays of ground antennas, such as the Very Long Baseline Array and European VLBI Network, to obtain high-resolution images of 27 active galactic nuclei and to measure the core brightness temperatures of these sources more accurately than is possible from the ground. A detailed analysis of the source properties is given in accompanying papers. We have also performed an extensive series of simulations to investigate the errors in VSOP images caused by the relatively large holes in the (u,v)-plane when sources are observed near the orbit normal direction. We find that while the nominal dynamic range (defined as the ratio of map peak to off-source error) often exceeds 1000:1, the true dynamic range (map peak to on-source error) is only about 30:1 for relatively complex core-jet sources. For sources dominated by a strong point source, this value rises to approximately 100:1. We find the true dynamic range to be a relatively weak function of the difference in position angle (P.A.) between the jet P.A. and u-v coverage major axis P.A. For regions with low signal-to-noise ratios, typically located down the jet away from the core, large errors can occur, causing spurious features in VSOP images that should be interpreted with caution.

Improving the Dynamic Emissivity Measurement Above 1000 K by Extending the Spectral Range

NASA Astrophysics Data System (ADS)

Urban, D.; Krenek, S.; Anhalt, K.; Taubert, D. R.

2018-01-01

To improve the dynamic emissivity measurement, which is based on the laser-flash method, an array spectrometer is characterized regarding its spectral radiance responsivity for a spectrally resolved emissivity measurement above 1000 K in the wavelength range between 550 nm and 1100 nm. Influences like dark signals, the nonlinearity of the detector, the size-of-source effect, wavelength calibration and the spectral radiance responsivity of the system are investigated to obtain an uncertainty budget for the spectral radiance and emissivity measurements. Uncertainties for the spectral radiance of lower than a relative 2 % are achieved for wavelengths longer than 550 nm. Finally, the spectral emissivity of a graphite sample was determined in the temperature range between 1000 K and 1700 K, and the experimental data show a good repeatability and agreement with literature data.

Nondestructive measurement of tomato postharvest quality using a multichannel hyperspectral imaging probe

USDA-ARS?s Scientific Manuscript database

A multichannel hyperspectral imaging probe with 30 optic fibers covering the wavelength range of 550-1,650 nm and the light source-detector distances of 1.5-36 mm was recently developed for optical property measurement and quality evaluation of food products with flat or curved surface. This paper r...

Geoacoustic inversion of a shallow fresh-water environment

NASA Astrophysics Data System (ADS)

Stotts, Steven A.; Knobles, David P.; Koch, Robert A.; Piper, James N.; Keller, Jason A.

2003-10-01

A recent experiment was conducted at The University of Texas/Applied Research Laboratories test station located at Lake Travis, Austin, TX. Implosive (light bulb), explosive (firecracker), and tonal sources were recorded on a dual receiver system located on the bottom next to a range-independent underwater river channel. Inversion results of the broadband time series obtained over ranges less than 1.5 km were used to predict measured transmission loss at several tonal frequencies in the band from 250-1000 Hz. The average water depth was approximately 38 m along the channel during the experiment. Sound speed profiles were calculated from recorded temperature readings measured as a function of depth. Implosive source spectrums were measured and used to evaluate a model/data correlation cost function in a simulated annealing algorithm. Comparisons of inversion results using both a normal mode and a ray-based plane wave reflection coefficient forward model [Stotts et al., J. Acoust. Soc. Am. (submitted)] are discussed. Predicted transmission loss based on the inversion results are compared to the measured transmission loss. Differences between fluid and elastic layer bottom models will also be presented.

An experimental investigation of alternative propellants for the helicon double layer thruster

NASA Astrophysics Data System (ADS)

Charles, C.; Boswell, R. W.; Laine, R.; MacLellan, P.

2008-09-01

Ion energy distribution functions are measured using a retarding field energy analyser located 7.5 cm downstream of a helicon double layer plasma source, respectively, operating with four molecular gases: nitrogen (N2), methane (CH4), ammonia (NH3) and nitrous oxide (N2O). For radiofrequency powers of a few hundred watts, and a magnetic field diverging from about 0.013 T (130 G) in the source to about 0.001 T (10 G) in the exhaust, an ion beam is detected for each propellant over a very similar operating pressure range (~0.023 Pa (0.17 mTorr) to ~0.267 Pa (2 mTorr)), as a result of spontaneous electric double layer formation near the exit of the plasma source. The characteristics of the ion beam versus operating pressure closely follow those previously obtained in argon, xenon and hydrogen. The ion beam exhaust velocity in space is found to be in the 17-19 km s-1 range in N2, 21-27 km s-1 range in CH4 and NH3 and 14-16 km s-1 range in N2O.

Spacecraft Internal Acoustic Environment Modeling

NASA Technical Reports Server (NTRS)

Chu, SShao-sheng R.; Allen, Christopher S.

2009-01-01

Acoustic modeling can be used to identify key noise sources, determine/analyze sub-allocated requirements, keep track of the accumulation of minor noise sources, and to predict vehicle noise levels at various stages in vehicle development, first with estimates of noise sources, later with experimental data. In FY09, the physical mockup developed in FY08, with interior geometric shape similar to Orion CM (Crew Module) IML (Interior Mode Line), was used to validate SEA (Statistical Energy Analysis) acoustic model development with realistic ventilation fan sources. The sound power levels of these sources were unknown a priori, as opposed to previous studies that RSS (Reference Sound Source) with known sound power level was used. The modeling results were evaluated based on comparisons to measurements of sound pressure levels over a wide frequency range, including the frequency range where SEA gives good results. Sound intensity measurement was performed over a rectangular-shaped grid system enclosing the ventilation fan source. Sound intensities were measured at the top, front, back, right, and left surfaces of the and system. Sound intensity at the bottom surface was not measured, but sound blocking material was placed tinder the bottom surface to reflect most of the incident sound energy back to the remaining measured surfaces. Integrating measured sound intensities over measured surfaces renders estimated sound power of the source. The reverberation time T6o of the mockup interior had been modified to match reverberation levels of ISS US Lab interior for speech frequency bands, i.e., 0.5k, 1k, 2k, 4 kHz, by attaching appropriately sized Thinsulate sound absorption material to the interior wall of the mockup. Sound absorption of Thinsulate was modeled in three methods: Sabine equation with measured mockup interior reverberation time T60, layup model based on past impedance tube testing, and layup model plus air absorption correction. The evaluation/validation was carried out by acquiring octave band microphone data simultaneously at ten fixed locations throughout the mockup. SPLs (Sound Pressure Levels) predicted by our SEA model match well with measurements for our CM mockup, with a more complicated shape. Additionally in FY09, background NC noise (Noise Criterion) simulation and MRT (Modified Rhyme Test) were developed and performed in the mockup to determine the maximum noise level in CM habitable volume for fair crew voice communications. Numerous demonstrations of simulated noise environment in the mockup and associated SIL (Speech Interference Level) via MRT were performed for various communities, including members from NASA and Orion prime-/sub-contractors. Also, a new HSIR (Human-Systems Integration Requirement) for limiting pre- and post-landing SIL was proposed.

Influence of Gridded Standoff Measurement Resolution on Numerical Bathymetric Inversion

NASA Astrophysics Data System (ADS)

Hesser, T.; Farthing, M. W.; Brodie, K.

2016-02-01

The bathymetry from the surfzone to the shoreline incurs frequent, active movement due to wave energy interacting with the seafloor. Methodologies to measure bathymetry range from point-source in-situ instruments, vessel-mounted single-beam or multi-beam sonar surveys, airborne bathymetric lidar, as well as inversion techniques from standoff measurements of wave processes from video or radar imagery. Each type of measurement has unique sources of error and spatial and temporal resolution and availability. Numerical bathymetry estimation frameworks can use these disparate data types in combination with model-based inversion techniques to produce a "best-estimate of bathymetry" at a given time. Understanding how the sources of error and varying spatial or temporal resolution of each data type affect the end result is critical for determining best practices and in turn increase the accuracy of bathymetry estimation techniques. In this work, we consider an initial step in the development of a complete framework for estimating bathymetry in the nearshore by focusing on gridded standoff measurements and in-situ point observations in model-based inversion at the U.S. Army Corps of Engineers Field Research Facility in Duck, NC. The standoff measurement methods return wave parameters computed using linear wave theory from the direct measurements. These gridded datasets can range in temporal and spatial resolution that do not match the desired model parameters and therefore could lead to a reduction in the accuracy of these methods. Specifically, we investigate the affect of numerical resolution on the accuracy of an Ensemble Kalman Filter bathymetric inversion technique in relation to the spatial and temporal resolution of the gridded standoff measurements. The accuracies of the bathymetric estimates are compared with both high-resolution Real Time Kinematic (RTK) single-beam surveys as well as alternative direct in-situ measurements using sonic altimeters.

A comparison of untagged gamma-ray and tagged-neutron yields from 241AmBe and 238PuBe sources.

PubMed

Scherzinger, J; Al Jebali, R; Annand, J R M; Fissum, K G; Hall-Wilton, R; Koufigar, S; Mauritzson, N; Messi, F; Perrey, H; Rofors, E

2017-09-01

Untagged gamma-ray and tagged-neutron yields from 241 AmBe and 238 PuBe mixed-field sources have been measured. Gamma-ray spectroscopy measurements from 1 to 5MeV were performed in an open environment using a CeBr 3 detector and the same experimental conditions for both sources. The shapes of the distributions are very similar and agree well with previous data. Tagged-neutron measurements from 2 to 6MeV were performed in a shielded environment using a NE-213 liquid-scintillator detector for the neutrons and a YAP(Ce) detector to tag the 4.44MeVgamma-rays associated with the de-excitation of the first-excited state of 12 C. Again, the same experimental conditions were used for both sources. The shapes of these distributions are also very similar and agree well with previous data, each other, and the ISO recommendation. Our 238 PuBe source provides approximately 2.6 times more 4.44MeVgamma-rays and 2.4 times more neutrons over the tagged-neutron energy range, the latter in reasonable agreement with the original full-spectrum source-calibration measurements performed at the time of their acquisition. Copyright © 2017 The Authors. Published by Elsevier Ltd.. All rights reserved.

Chorus Whistler Wave Source Scales As Determined From Multipoint Van Allen Probe Measurements

NASA Technical Reports Server (NTRS)

Agapitov, O.; Blum, L. W.; Mozer, F. S.; Bonnell, J. W.; Wygant, J.

2017-01-01

Whistler mode chorus waves are particularly important in outer radiation belt dynamics due to their key role in controlling the acceleration and scattering of electrons over a very wide energy range. The key parameters for both nonlinear and quasi-linear treatment of wave-particle interactions are the temporal and spatial scales of the wave source region and coherence of the wave field perturbations. Neither the source scale nor the coherence scale is well established experimentally, mostly because of a lack of multipoint VLF waveform measurements. We present an unprecedentedly long interval of coordinated VLF waveform measurements (sampled at 16384 s(exp -1)) aboard the two Van Allen Probes spacecraft-9 h (0800-1200 UT and 1700-2200 UT) during two consecutive apogees on 15 July 2014. The spacecraft separations varied from about 100 to 5000 km (mostly radially); measurements covered an L shell range from 3 to 6; magnetic local time 0430-0900, and magnetic latitudes were approximately 15 and approximately 5 deg during the two orbits. Using time-domain correlation techniques, the single chorus source spatial extent transverse to the background magnetic field has been determined to be about 550-650 km for upper band chorus waves with amplitudes less than 100 pT and up to 800 km for larger amplitude, lower band chorus waves. The ratio between wave amplitudes measured on the two spacecraft is also examined to reveal that the wave amplitude distribution within a single chorus element generation area can be well approximated by a Gaussian exp(-0.5 x r (exp 2)/r(sub 0)(exp 2)), with the characteristic scale r(sub 0) around 300 km. Waves detected by the two spacecraft were found to be coherent in phase at distances up to 400 km.

Nonevaporable getter coating chambers for extreme high vacuum

DOE PAGES

Stutzman, Marcy L.; Adderley, Philip A.; Mamun, Md Abdullah Al; ...

2018-03-01

Techniques for NEG coating a large diameter chamber are presented along with vacuum measurements in the chamber using several pumping configurations, with base pressure as low as 1.56x10^-12 Torr (N2 equivalent) with only a NEG coating and small ion pump. We then describe modifications to the NEG coating process to coat complex geometry chambers for ultra-cold atom trap experiments. Surface analysis of NEG coated samples are used to measure composition and morphology of the thin films. Finally, pressure measurements are compared for two NEG coated polarized electron source chambers: the 130 kV polarized electron source at Jefferson Lab and themore » upgraded 350 kV polarized 2 electron source, both of which are approaching or within the extreme high vacuum (XHV) range, defined as P<7.5x10^-13 Torr.« less

Nonevaporable getter coating chambers for extreme high vacuum

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

Stutzman, Marcy L.; Adderley, Philip A.; Mamun, Md Abdullah Al

Techniques for NEG coating a large diameter chamber are presented along with vacuum measurements in the chamber using several pumping configurations, with base pressure as low as 1.56x10^-12 Torr (N2 equivalent) with only a NEG coating and small ion pump. We then describe modifications to the NEG coating process to coat complex geometry chambers for ultra-cold atom trap experiments. Surface analysis of NEG coated samples are used to measure composition and morphology of the thin films. Finally, pressure measurements are compared for two NEG coated polarized electron source chambers: the 130 kV polarized electron source at Jefferson Lab and themore » upgraded 350 kV polarized 2 electron source, both of which are approaching or within the extreme high vacuum (XHV) range, defined as P<7.5x10^-13 Torr.« less

Stereotypical rapid source level regulation in the harbour porpoise biosonar.

PubMed

Linnenschmidt, Meike; Kloepper, Laura N; Wahlberg, Magnus; Nachtigall, Paul E

2012-09-01

Some odontocetes and bats vary both click intensity and receiver sensitivity during echolocation, depending on target range. It is not known how this so-called automatic gain control is regulated by the animal. The source level of consecutive echolocation clicks from a harbour porpoise was measured with a hydrophone array while the animal detected an aluminium cylinder at 2, 4 or 8 m distance in a go/no-go paradigm. On-axis clicks had source levels of 145-174 dB re 1 μPa peak-to-peak. During target-present trials the click trains reached comparable source levels independent of the range to the target after three clicks. After an additional click, the source level was reduced for the 2 and 4 m trials until it equalled the one-way transmission loss. During target-absent trials, the source level remained high throughout the entire click train. Given typical values of harbour porpoise inter-click intervals, the source level reduction commenced within a few 100 ms from the first click in the click train. This may indicate a sub-cortically regulated source level regulation in the harbour porpoise.

Sources of Dimethyl Sulfide in the Canadian Arctic Archipelago and Baffin Bay

NASA Astrophysics Data System (ADS)

Mungall, E. L.; Croft, B.; Lizotte, M.; Thomas, J. L.; Murphy, J. G.; Levasseur, M.; Martin, R.; Wentzell, J. J. B.; Liggio, J.; Abbatt, J.

2015-12-01

Dimethyl sulfide plays a major role in the global sulfur cycle, meaning that it is important to the formation of sulfate aerosol and thus to cloud condensation nuclei populations and cloud formation. The summertime Arctic atmosphere sometimes resides in a cloud condensation nuclei limited regime, making it very susceptible to changes in their number. Despite the interest generated by this situation, dimethyl sulfide has only rarely been measured in the summertime Arctic. This work presents the first high time resolution (10 Hz) DMS mixing ratio measurements for the Eastern Canadian Archipelago and Baffin Bay in summer performed on an icebreaker cruise as one component of the Network on Climate and Aerosols: Addressing Key Uncertainties in Remote Canadian Environments (NETCARE). Measured mixing ratios ranged from below the detection limit of 4 pptv to 1155 pptv with a median value of 186 pptv. We used transfer velocity parameterizations from the literature to generate the first flux estimates for this region in summer, which ranged from 0.02-12 μmol m-2 d-1. DMS has a lifetime against OH oxidation of 1-2 days, allowing both local sources and transport to play roles in its atmospheric mixing ratio. Through air mass trajectory analysis using FLEXPART-WRF and chemical transport modeling using GEOS-Chem, we have identified the relative contributions of local sources (Lancaster Sound and Baffin Bay) as well as transport from further afield (the Hudson Bay System and the Beaufort Sea) and find that the local sources dominate. GEOS-Chem is able to reproduce the major features of the measured time series, but is biased low overall (median 72 pptv). We discuss non-marine sources that could account for this low bias and estimate the possible contributions to DMS mixing ratios from lakes, biomass burning, melt ponds and coastal tundra. Our results show that local marine sources of DMS dominate the summer Arctic atmosphere, but that non-local and possibly non-marine contributions have a detectable influence.

Photoionization Efficiencies of Five Polycyclic Aromatic Hydrocarbons.

PubMed

Johansson, K Olof; Campbell, Matthew F; Elvati, Paolo; Schrader, Paul E; Zádor, Judit; Richards-Henderson, Nicole K; Wilson, Kevin R; Violi, Angela; Michelsen, Hope A

2017-06-15

We have measured photoionization-efficiency curves for pyrene, fluoranthene, chrysene, perylene, and coronene in the photon energy range of 7.5-10.2 eV and derived their photoionization cross-section curves in this energy range. All measurements were performed using tunable vacuum ultraviolet (VUV) radiation generated at the Advanced Light Source synchrotron at Lawrence Berkeley National Laboratory. The VUV radiation was used for photoionization, and detection was performed using a time-of-flight mass spectrometer. We measured the photoionization efficiency of 2,5-dimethylfuran simultaneously with those of pyrene, fluoranthene, chrysene, perylene, and coronene to obtain references of the photon flux during each measurement from the known photoionization cross-section curve of 2,5-dimethylfuran.

Predicting Secchi disk depth from average beam attenuation in a deep, ultra-clear lake

USGS Publications Warehouse

Larson, G.L.; Hoffman, R.L.; Hargreaves, B.R.; Collier, R.W.

2007-01-01

We addressed potential sources of error in estimating the water clarity of mountain lakes by investigating the use of beam transmissometer measurements to estimate Secchi disk depth. The optical properties Secchi disk depth (SD) and beam transmissometer attenuation (BA) were measured in Crater Lake (Crater Lake National Park, Oregon, USA) at a designated sampling station near the maximum depth of the lake. A standard 20 cm black and white disk was used to measure SD. The transmissometer light source had a nearly monochromatic wavelength of 660 nm and a path length of 25 cm. We created a SD prediction model by regression of the inverse SD of 13 measurements recorded on days when environmental conditions were acceptable for disk deployment with BA averaged over the same depth range as the measured SD. The relationship between inverse SD and averaged BA was significant and the average 95% confidence interval for predicted SD relative to the measured SD was ??1.6 m (range = -4.6 to 5.5 m) or ??5.0%. Eleven additional sample dates tested the accuracy of the predictive model. The average 95% confidence interval for these sample dates was ??0.7 m (range = -3.5 to 3.8 m) or ??2.2%. The 1996-2000 time-series means for measured and predicted SD varied by 0.1 m, and the medians varied by 0.5 m. The time-series mean annual measured and predicted SD's also varied little, with intra-annual differences between measured and predicted mean annual SD ranging from -2.1 to 0.1 m. The results demonstrated that this prediction model reliably estimated Secchi disk depths and can be used to significantly expand optical observations in an environment where the conditions for standardized SD deployments are limited. ?? 2007 Springer Science+Business Media B.V.

Robo-AO Kepler Asteroseismic Survey. I. Adaptive Optics Imaging of 99 Asteroseismic Kepler Dwarfs and Subgiants

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

Schonhut-Stasik, Jessica S.; Baranec, Christoph; Huber, Daniel

We used the Robo-AO laser adaptive optics (AOs) system to image 99 main sequence and subgiant stars that have Kepler -detected asteroseismic signals. Robo-AO allows us to resolve blended secondary sources at separations as close as ∼0.″15 that may contribute to the measured Kepler light curves and affect asteroseismic analysis and interpretation. We report eight new secondary sources within 4.″0 of these Kepler asteroseismic stars. We used Subaru and Keck AOs to measure differential infrared photometry for these candidate companion systems. Two of the secondary sources are likely foreground objects, while the remaining six are background sources; however, we cannotmore » exclude the possibility that three of the objects may be physically associated. We measured a range of i ′-band amplitude dilutions for the candidate companion systems from 0.43% to 15.4%. We find that the measured amplitude dilutions are insufficient to explain the previously identified excess scatter in the relationship between asteroseismic oscillation amplitude and the frequency of maximum power.« less

Optimising measurement of health-related characteristics of the built environment: Comparing data collected by foot-based street audits, virtual street audits and routine secondary data sources.

PubMed

Pliakas, Triantafyllos; Hawkesworth, Sophie; Silverwood, Richard J; Nanchahal, Kiran; Grundy, Chris; Armstrong, Ben; Casas, Juan Pablo; Morris, Richard W; Wilkinson, Paul; Lock, Karen

2017-01-01

The role of the neighbourhood environment in influencing health behaviours continues to be an important topic in public health research and policy. Foot-based street audits, virtual street audits and secondary data sources are widespread data collection methods used to objectively measure the built environment in environment-health association studies. We compared these three methods using data collected in a nationally representative epidemiological study in 17 British towns to inform future development of research tools. There was good agreement between foot-based and virtual audit tools. Foot based audits were superior for fine detail features. Secondary data sources measured very different aspects of the local environment that could be used to derive a range of environmental measures if validated properly. Future built environment research should design studies a priori using multiple approaches and varied data sources in order to best capture features that operate on different health behaviours at varying spatial scales. Copyright © 2016 The Authors. Published by Elsevier Ltd.. All rights reserved.

Investigation of hydraulic transmission noise sources

NASA Astrophysics Data System (ADS)

Klop, Richard J.

Advanced hydrostatic transmissions and hydraulic hybrids show potential in new market segments such as commercial vehicles and passenger cars. Such new applications regard low noise generation as a high priority, thus, demanding new quiet hydrostatic transmission designs. In this thesis, the aim is to investigate noise sources of hydrostatic transmissions to discover strategies for designing compact and quiet solutions. A model has been developed to capture the interaction of a pump and motor working in a hydrostatic transmission and to predict overall noise sources. This model allows a designer to compare noise sources for various configurations and to design compact and inherently quiet solutions. The model describes dynamics of the system by coupling lumped parameter pump and motor models with a one-dimensional unsteady compressible transmission line model. The model has been verified with dynamic pressure measurements in the line over a wide operating range for several system structures. Simulation studies were performed illustrating sensitivities of several design variables and the potential of the model to design transmissions with minimal noise sources. A semi-anechoic chamber has been designed and constructed suitable for sound intensity measurements that can be used to derive sound power. Measurements proved the potential to reduce audible noise by predicting and reducing both noise sources. Sound power measurements were conducted on a series hybrid transmission test bench to validate the model and compare predicted noise sources with sound power.

Lightning Technology (Supplement)

DTIC Science & Technology

1981-01-01

material presented in this report was taken from a variety of sources; therefore, various units of measure are used. Use of trade names or names of...Clifford, and W. G. Butters 3. IMPLEMENTATION AND EXPERIENCE WITH LIGHTNING HARDENING MEASURES ON THE NAVY/AIR FORCE COMBAT MANEUVERING RANGES...overall lightning event taken from an appropriate base of wideband measurements . In 1979, the Air Force Wright Aeronautical Laboratories began a joint

Thermal conductivity of particulate materials: A summary of measurements taken at the Marshall Space Flight Center

NASA Technical Reports Server (NTRS)

Fountain, J. A.

1973-01-01

Thermal conductivity measurements of particulate materials in vacuum are presented in summary. Particulate basalt and soda lime glass beads of various size ranges were used as samples. The differentiated line heat source method was used for the measurements. A comprehensive table is shown giving all pertinent experimental conditions. Least-squares curve fits to the data are presented.

Adaptive Estimation and Heuristic Optimization of Nonlinear Spacecraft Attitude Dynamics

DTIC Science & Technology

2016-09-15

Algorithm GPS Global Positioning System HOUF Higher Order Unscented Filter IC initial conditions IMM Interacting Multiple Model IMU Inertial Measurement Unit ...sources ranging from inertial measurement units to star sensors are used to construct observations for attitude estimation algorithms. The sensor...parameters. A single vector measurement will provide two independent parameters, as a unit vector constraint removes a DOF making the problem underdetermined

An overview of NASA's ASCENDS Mission's Lidar Measurement Requirements

NASA Astrophysics Data System (ADS)

Abshire, J. B.; Browell, E. V.; Menzies, R. T.; Lin, B.; Spiers, G. D.; Ismail, S.

2014-12-01

The objectives of NASA's ASCENDS mission are to improve the knowledge of global CO2 sources and sinks by precisely measuring the tropospheric column abundance of atmospheric CO2 and O2. The mission will use a continuously operating nadir-pointed integrated path differential absorption (IPDA) lidar in a polar orbit. The lidar offers a number of important new capabilities and will measure atmospheric CO2 globally over a wide range of challenging conditions, including at night, at high latitudes, through hazy and thin cloud conditions, and to cloud tops. The laser source enables a measurement of range, so that the absorption path length to the scattering surface will be always accurately known. The lidar approach also measures consistently in a nadir-zenith path and the narrow laser linewidth allows weighting the measurement to the lower troposphere. Using these measurements with atmospheric and flux models will allow improved estimates of CO2 fluxes and hence better understanding of the processes that exchange CO2 between the surface and atmosphere. The ASCENDS formulation team has developed a preliminary set of requirements for the lidar measurements. These were developed based on experience gained from the numerous ASCENDS airborne campaigns that have used different candidate lidar measurement techniques. They also take into account the complexity of making precise measurement of atmospheric gas columns when viewing the Earth from space. Some of the complicating factors are the widely varying reflectance and topographic heights of the Earth's land and ocean surfaces, the variety of cloud types, and the degree of cloud and aerosol absorption and scattering in the atmosphere. The requirements address the precision and bias in the measured column mixing ratio, the dynamic range of the expected surface reflected signal, the along-track sampling resolution, measurements made through thin clouds, measurements to forested and slope surfaces, range precision, measurements to cloud tops, knowledge of the laser spot position, and off-nadir pointing. These requirements are independent of the measurement approach, and are consistent with the initial mission simulation studies performed by the formulation team. This presentation will summarize the requirements along with examples that have guided their selection.

A 2.5-2.7 THz Room Temperature Electronic Source

NASA Technical Reports Server (NTRS)

Maestrini, Alain; Mehdi, Imran; Lin, Robert; Siles, Jose Vicente; Lee, Choonsup; Gill, John; Chattopadhyay, Goutam; Schlecht, Erich; Bertrand, Thomas; Ward, John

2011-01-01

We report on a room temperature 2.5 to 2.7 THz electronic source based on frequency multipliers. The source utilizes a cascade of three frequency multipliers with W-band power amplifiers driving the first stage multiplier. Multiple-chip multipliers are utilized for the two initial stages to improve the power handling capability and a sub-micron anode is utilized for the final stage tripler. Room temperature measurements indicate that the source can put out a peak power of about 14 microwatts with more than 4 microwatts in the 2.5 to 2.7 THz range.

Estimating uncertainty in subsurface glider position using transmissions from fixed acoustic tomography sources.

PubMed

Van Uffelen, Lora J; Nosal, Eva-Marie; Howe, Bruce M; Carter, Glenn S; Worcester, Peter F; Dzieciuch, Matthew A; Heaney, Kevin D; Campbell, Richard L; Cross, Patrick S

2013-10-01

Four acoustic Seagliders were deployed in the Philippine Sea November 2010 to April 2011 in the vicinity of an acoustic tomography array. The gliders recorded over 2000 broadband transmissions at ranges up to 700 km from moored acoustic sources as they transited between mooring sites. The precision of glider positioning at the time of acoustic reception is important to resolve the fundamental ambiguity between position and sound speed. The Seagliders utilized GPS at the surface and a kinematic model below for positioning. The gliders were typically underwater for about 6.4 h, diving to depths of 1000 m and traveling on average 3.6 km during a dive. Measured acoustic arrival peaks were unambiguously associated with predicted ray arrivals. Statistics of travel-time offsets between received arrivals and acoustic predictions were used to estimate range uncertainty. Range (travel time) uncertainty between the source and the glider position from the kinematic model is estimated to be 639 m (426 ms) rms. Least-squares solutions for glider position estimated from acoustically derived ranges from 5 sources differed by 914 m rms from modeled positions, with estimated uncertainty of 106 m rms in horizontal position. Error analysis included 70 ms rms of uncertainty due to oceanic sound-speed variability.

Absolute calibration of a hydrogen discharge lamp in the vacuum ultraviolet

NASA Technical Reports Server (NTRS)

Nealy, J. E.

1975-01-01

A low-pressure hydrogen discharge lamp was calibrated for radiant intensity in the vacuum ultraviolet spectral region on an absolute basis and was employed as a laboratory standard source in spectrograph calibrations. This calibration was accomplished through the use of a standard photodiode detector obtained from the National Bureau of Standards together with onsite measurements of spectral properties of optical components used. The stability of the light source for use in the calibration of vacuum ultraviolet spectrographs and optical systems was investigated and found to be amenable to laboratory applications. The lamp was studied for a range of operating parameters; the results indicate that with appropriate peripheral instrumentation, the light source can be used as a secondary laboratory standard source when operated under preset controlled conditions. Absolute intensity measurements were recorded for the wavelengths 127.7, 158.0, 177.5, and 195.0 nm for a time period of over 1 month, and the measurements were found to be repeatable to within 11 percent.

The Chandra Source Catalog: X-ray Aperture Photometry

NASA Astrophysics Data System (ADS)

Kashyap, Vinay; Primini, F. A.; Glotfelty, K. J.; Anderson, C. S.; Bonaventura, N. R.; Chen, J. C.; Davis, J. E.; Doe, S. M.; Evans, I. N.; Evans, J. D.; Fabbiano, G.; Galle, E. C.; Gibbs, D. G., II; Grier, J. D.; Hain, R.; Hall, D. M.; Harbo, P. N.; He, X.; Houck, J. C.; Karovska, M.; Lauer, J.; McCollough, M. L.; McDowell, J. C.; Miller, J. B.; Mitschang, A. W.; Morgan, D. L.; Nichols, J. S.; Nowak, M. A.; Plummer, D. A.; Refsdal, B. L.; Rots, A. H.; Siemiginowska, A. L.; Sundheim, B. A.; Tibbetts, M. S.; van Stone, D. W.; Winkelman, S. L.; Zografou, P.

2009-09-01

The Chandra Source Catalog (CSC) represents a reanalysis of the entire ACIS and HRC imaging observations over the 9-year Chandra mission. We describe here the method by which fluxes are measured for detected sources. Source detection is carried out on a uniform basis, using the CIAO tool wavdetect. Source fluxes are estimated post-facto using a Bayesian method that accounts for background, spatial resolution effects, and contamination from nearby sources. We use gamma-function prior distributions, which could be either non-informative, or in case there exist previous observations of the same source, strongly informative. The current implementation is however limited to non-informative priors. The resulting posterior probability density functions allow us to report the flux and a robust credible range on it.

Performance comparison of NE213 detectors for their application in moisture measurement

PubMed

Naqvi; Nagadi; Rehman; Kidwai

2000-10-01

The pulse shape discrimination (PSD) characteristic and neutron detection efficiency of NE213 detectors have been measured for their application in moisture measurements using 252Cf and 241Am-Be sources. In PSD studies, neutron peak to valley (Pn/V) ratio and figure of merit M were measured at four different bias values for cylindrical 50, 125 and 250 mm diameter NE213 detectors. The result of this study has shown that better PSD performance with the NE213 detector can be achieved with a smaller volume detector in conjunction with a neutron source with smaller gamma-ray/neutron ratio. The neutron detection efficiency of the 125 mm diameter NE213 detector for 241Am-Be and 252Cf source spectra was determined at 0.85, 1.25 and 1.75 MeV bias energies using the experimental neutron detection efficiency data of the same detector over 0.1-10 MeV energy range. Due to different energy spectra of the 241Am-Be and 252Cf sources, integrated efficiency of the 125 mm diameter NE213 detector for the two sources shows bias dependence. At smaller bias, 252Cf source has larger efficiency but as the bias is increased, the detector has larger efficiency for 241Am-Be source. This study has revealed that NE213 detector has better performance (such as PSD and neutron detection efficiency) in simultaneous detection of neutron and gamma-rays in moisture measurements, if it is used in conjunction with 241Am-Be source at higher detector bias.

Dynamic granularity of imaging systems

DOE PAGES

Geissel, Matthias; Smith, Ian C.; Shores, Jonathon E.; ...

2015-11-04

Imaging systems that include a specific source, imaging concept, geometry, and detector have unique properties such as signal-to-noise ratio, dynamic range, spatial resolution, distortions, and contrast. Some of these properties are inherently connected, particularly dynamic range and spatial resolution. It must be emphasized that spatial resolution is not a single number but must be seen in the context of dynamic range and consequently is better described by a function or distribution. We introduce the “dynamic granularity” G dyn as a standardized, objective relation between a detector’s spatial resolution (granularity) and dynamic range for complex imaging systems in a given environmentmore » rather than the widely found characterization of detectors such as cameras or films by themselves. We found that this relation can partly be explained through consideration of the signal’s photon statistics, background noise, and detector sensitivity, but a comprehensive description including some unpredictable data such as dust, damages, or an unknown spectral distribution will ultimately have to be based on measurements. Measured dynamic granularities can be objectively used to assess the limits of an imaging system’s performance including all contributing noise sources and to qualify the influence of alternative components within an imaging system. Our article explains the construction criteria to formulate a dynamic granularity and compares measured dynamic granularities for different detectors used in the X-ray backlighting scheme employed at Sandia’s Z-Backlighter facility.« less

Measurement of Jovian decametric Io-related source location and beam shape

NASA Technical Reports Server (NTRS)

Maeda, K.; Carr, T. D.

1992-01-01

The paper presents new information on the locations of the Io-related sources A and C (i.e., Io-A and Io-C) and on the shapes of their emission beams on the basis of measurements of the Jovian decametric activity that was recorded by Voyager 1 and 2. In two instances, the same dynamic spectral arc event in the recorded data of the two spacecraft was recorded, providing in each case an opportunity to observe the same emission beam over a wide range of frequencies from two considerably different directions. The propagation-corrected centroid times of each of the Voyager-1 arcs are found to be coincident with those of the corresponding Voyager-2 arc in a particular frequency range, but not at other frequencies. The hypothesis that emission beams are in the form of thin, almost conical sheets, the cone opening angle decreasing with increasing frequency, is confirmed. It is demonstrated that both the Io-A and Io-C sources were located near the northern foot of the magnetic flux tube that was connected to Io.

Low latitude middle atmosphere ionization studies

NASA Technical Reports Server (NTRS)

Bassi, J. P.

1976-01-01

Low latitude middle atmosphere ionization was studied with data obtained from three blunt conductivity probes and one Gerdien condenser. An investigation was conducted into the effects of various ionization sources in the 40 to 65 Km altitude range. An observed enhancement of positive ion conductivity taking place during the night can be explained by an atmsopheric effect, with cosmic rays being the only source of ionization only if the ion-ion recombination coefficient (alpha sub i) is small(10 to the -7 power cu cm/s) and varies greatly with altitude. More generally accepted values of alpha sub i ( approximately equal to 3x10 to the -7 power cu cm/s) require an additional source of ionization peaking at about 65 Km, and corresponding approximately to the integrated effect of an X-ray flux measured on a rocket flown in conjunction with the ionization measurements. The reasonable assumption of an alpha sub i which does not vary with altitude in the 50-70 Km range implies an even greater value alpha sub i and a more intense and harder X-ray spectrum.

A new seismic probe for coal seam hazard detection

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

Peters, W.R.; Owen, T.E.; Thill, R.E.

1985-01-01

An experimental hole-to-hole seismic probe system has been developed for use in coal measure geology as a means of determining the structural conditions of coal seams. The source probe produces a 500-joule electric arc discharge whose seismic wavelet has a spectrum in the 200 to 2,000 Hz frequency range. Low compliance hydrophones contained in the source probe as well as in a separate seismic detector probe are matched to the frequency range of the source. Both probes are constructed with 5.72 cm diameter housings. The transducers in the probes are equipped with fluid-inflatable boots to permit operation in either wetmore » or dry boreholes. Preliminary tests in vertical boreholes drilled 213 m apart in sedimentary rock formations show reliable operation and useful seismic propagation measurements along horizontal and oblique paths up to 232 m in length. Because the seismic wavelet has an accurately repeatable waveshape, multiple shots and signal averaging techniques can be used to enhance the signal-to-noise ratio and extend the transmission distances.« less

Split-spectrum intensity-based optical fiber sensors for measurement of microdisplacement, strain, and pressure

NASA Astrophysics Data System (ADS)

Wang, Anbo; Miller, Mark S.; Plante, Angela J.; Gunther, Michael F.; Murphy, Kent A.; Claus, Richard O.

1996-05-01

A self-referencing technique compensating for fiber losses and source fluctuations in reflective air-gap intensity-based optical fiber sensors is described. A dielectric multilayer short-wave-pass filter is fabricated onto or attached to the output end face of the lead-in-lead-out multimode fiber. The incoming broadband light from a white light or a light-emitting diode is partially reflected at the filter. The transmitted light through the filter projects onto a mirror. The light returning from the reflecting mirror is recoupled into the lead-in-lead-out fiber. These two reflections from the filter and the reflecting mirror are spectrally separated at the detector end. The power ratio of these two reflections is insensitive to source fluctuations and fiber-bending loss. However, because the second optical signal depends on the air-gap separation between the end face of the lead-in-lead-out fiber and the reflecting mirror, the ratio provides the information on the air-gap length. A resolution of 0.13 mu m has been obtained over a microdisplacement measurement range of 0-254 mu m. The sensor is shown to be insensitive to both fiber-bending losses and variations in source power. Based on this approach, a fiber-strain sensor was fabricated with a multilayer interference filter directly fabricated on the end face of the fiber. A resolution of 13.4 microstrain was obtained over a measurement range of 0-20,000 microstrain with a gauge length of 10 mm. The split-spectrum method is also incorporated into a diaphragm displacement-based pressure sensor with a demonstrated resolution of 450 Pa over a measurement range of 0-0.8 MPa.

Radon Levels Measured at a Touristic Thermal Spa Resort in Montagu (South Africa) and Associated Effective Doses.

PubMed

Botha, R; Newman, R T; Maleka, P P

2016-09-01

Radon activity concentrations (in water and in air) were measured at 13 selected locations at the Avalon Springs thermal spa resort in Montagu (Western Cape, South Africa) to estimate the associated effective dose received by employees and visitors. A RAD-7 detector (DURRIDGE), based on alpha spectrometry, and electret detectors (E-PERM®Radelec) were used for these radon measurements. The primary source of radon was natural thermal waters from the hot spring, which were pumped to various locations on the resort, and consequently a range of radon in-water analyses were performed. Radon in-water activity concentration as a function of time (short term and long term measurements) and spatial distributions (different bathing pools, etc.) were studied. The mean radon in-water activity concentrations were found to be 205 ± 6 Bq L (source), 112 ± 5 Bq L (outdoor pool) and 79 ± 4 Bq L (indoor pool). Radon in-air activity concentrations were found to range between 33 ± 4 Bq m (at the outside bar) to 523 ± 26 Bq m (building enclosing the hot spring's source). The most significant potential radiation exposure identified is that due to inhalation of air rich in radon and its progeny by the resort employees. The annual occupational effective dose due to the inhalation of radon progeny ranges from 0.16 ± 0.01 mSv to 0.40 ± 0.02 mSv. For the water samples collected, the Ra in-water activity concentrations from samples collected were below the lower detection limit (~0.7 Bq L) of the γ-ray detector system used. No significant radiological health risk can be associated with radon and progeny from the hot spring at the Avalon Springs resort.

Probable LAGEOS contributions to a worldwide geodynamics control network

NASA Technical Reports Server (NTRS)

Bender, P. L.; Goad, C. C.

1979-01-01

The paper describes simulations performed on the contributions which LAGEOS laser ranging data can make to the establishment of a worldwide geodynamics control network. A distribution of 10 fixed ranging stations was assumed for most of the calculations, and a single 7-day arc was used, measurements assumed to be made every 10 minutes in order to avoid artificial reductions in the uncertainties due to oversampling. Computer simulations were carried out in which the coordinates of the stations and improvements in the gravity field coefficients were solved for simultaneously. It is suggested that good accuracy for station coordinates can be expected, even with the present gravity field model uncertainties, if sufficient measurement accuracy is achieved at a reasonable distribution of stations. Further, it is found that even 2-cm range measurement errors would be likely to be the main source of station coordinate errors in retrospective analyses of LAGEOS ranging results five or six years from now.

The Mars Observer differential one-way range demonstration

NASA Technical Reports Server (NTRS)

Kroger, P. M.; Border, J. S.; Nandi, S.

1994-01-01

Current methods of angular spacecraft positioning using station differenced range data require an additional observation of an extragalactic radio source (quasar) to estimate the timing offset between the reference clocks at the two Deep Space Stations. The quasar observation is also used to reduce the effects of instrumental and media delays on the radio metric observable by forming a difference with the spacecraft observation (delta differential one-way range, delta DOR). An experiment has been completed using data from the Global Positioning System satellites to estimate the station clock offset, eliminating the need for the quasar observation. The requirements for direct measurement of the instrumental delays that must be made in the absence of a quasar observation are assessed. Finally, the results of the 'quasar-free' differential one-way range, or DOR, measurements of the Mars Observer spacecraft are compared with those of simultaneous conventional delta DOR measurements.

Free tropospheric measurements of CS2 over a 45 deg N to 45 deg S latitude range

NASA Technical Reports Server (NTRS)

Tucker, B. J.; Maroulis, P. J.; Bandy, A. R.

1985-01-01

The mean value obtained from 52 free tropospheric measurements of CS2 over the 45 deg N-45 deg S latitude range was 5.7 pptv, with standard deviation and standard error of 1.9 and 0.3 pptv, respectively. Large fluctuations in the CS2 concentration are observed which reflect the apparent short atmospheric residence time and inhomogeneities in the surface sources of CS2. The amounts of CS2 in the Northern and Southern Hemispheres are statistically equal.

A new method for determining the plasma electron density using optical frequency comb interferometer

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

Arakawa, Hiroyuki, E-mail: arakawa@fmt.teikyo-u.ac.jp; Tojo, Hiroshi; Sasao, Hajime

2014-04-15

A new method of plasma electron density measurement using interferometric phases (fractional fringes) of an optical frequency comb interferometer is proposed. Using the characteristics of the optical frequency comb laser, high density measurement can be achieved without fringe counting errors. Simulations show that the short wavelength and wide wavelength range of the laser source and low noise in interferometric phases measurements are effective to reduce ambiguity of measured density.

Are changing emission patterns across the Northern Hemisphere influencing long-range transport contributions to background air pollution?

NASA Astrophysics Data System (ADS)

Mathur, R.; Kang, D.; Napelenok, S. L.; Xing, J.; Hogrefe, C.

2017-12-01

Air pollution reduction strategies for a region are complicated not only by the interplay of local emissions sources and several complex physical, chemical, dynamical processes in the atmosphere, but also hemispheric background levels of pollutants. Contrasting changes in emission patterns across the globe (e.g. declining emissions in North America and Western Europe in response to implementation of control measures and increasing emissions across Asia due to economic and population growth) are resulting in heterogeneous changes in the tropospheric chemical composition and are likely altering long-range transport impacts and consequently background pollution levels at receptor regions. To quantify these impacts, the WRF-CMAQ model is expanded to hemispheric scales and multi-decadal model simulations are performed for the period spanning 1990-2010 to examine changes in hemispheric air pollution resulting from changes in emissions over this period. Simulated trends in ozone and precursor species concentrations across the U.S. and the Northern Hemisphere over the past two decades are compared with those inferred from available measurements during this period. Additionally, the decoupled direct method (DDM) in CMAQ, a first- and higher-order sensitivity calculation technique, is used to estimate the sensitivity of O3 to emissions from different source regions across the Northern Hemisphere. The seasonal variations in source region contributions to background O3 are then estimated from these sensitivity calculations and will be discussed. These source region sensitivities estimated from DDM are then combined with the multi-decadal simulations of O3 distributions and emissions trends to characterize the changing contributions of different source regions to background O3 levels across North America. This characterization of changing long-range transport contributions is critical for the design and implementation of tighter national air quality standards

The range and intensity of backscattered electrons for use in the creation of high fidelity electron beam lithography patterns.

PubMed

Czaplewski, David A; Holt, Martin V; Ocola, Leonidas E

2013-08-02

We present a set of universal curves that predict the range and intensity of backscattered electrons which can be used in conjunction with electron beam lithography to create high fidelity nanoscale patterns. The experimental method combines direct write dose, backscattered dose, and a self-reinforcing pattern geometry to measure the dose provided by backscattered electrons to a nanoscale volume on the substrate surface at various distances from the electron source. Electron beam lithography is used to precisely control the number and position of incident electrons on the surface of the material. Atomic force microscopy is used to measure the height of the negative electron beam lithography resist. Our data shows that the range and the intensity of backscattered electrons can be predicted using the density and the atomic number of any solid material, respectively. The data agrees with two independent Monte Carlo simulations without any fitting parameters. These measurements are the most accurate electron range measurements to date.

Surface roughness measurement in the submicrometer range using laser scattering

NASA Astrophysics Data System (ADS)

Wang, S. H.; Quan, Chenggen; Tay, C. J.; Shang, H. M.

2000-06-01

A technique for measuring surface roughness in the submicrometer range is developed. The principle of the method is based on laser scattering from a rough surface. A telecentric optical setup that uses a laser diode as a light source is used to record the light field scattered from the surface of a rough object. The light intensity distribution of the scattered band, which is correlated to the surface roughness, is recorded by a linear photodiode array and analyzed using a single-chip microcomputer. Several sets of test surfaces prepared by different machining processes are measured and a method for the evaluation of surface roughness is proposed.

Shock tube measurements of the optical absorption of triatomic carbon, C3

NASA Technical Reports Server (NTRS)

Jones, J. J.

1977-01-01

The spectral absorption of C3 has been measured in a shock tube using a test gas mixture of acetylene diluted with argon. The absorption of a pulsed xenon light source was measured by means of eight photomultiplier channels to a spectrograph and an accompanying drum camera. The postshock test gas temperature and pressure were varied over the range 3300-4300 K and 0.36 to 2.13 atmospheres, respectively. The results showed appreciable absorption from C3 for the wavelength range 300 to 540 nanometers. The computed electronic oscillator strength varied from 0.12 to 0.06 as a function of temperature.

Multipoint sensing with a low-coherence source using single-arm frequency-shifted interferometry

DOE PAGES

Zhang, Yiwei; Ye, Fei; Qi, Bing; ...

2016-07-12

We demonstrate that multiple-site sensing along an optical fiber can be done with incoherent continuous-wave light. Here, using a broadband low-coherence noise source, a slow detector, and an optical modulator, we construct a single-arm frequency-shifted interferometer (SA-FSI) capable of simultaneously sensing multiple weak-reflection sites distributed either in parallel or in series along fiber links. By scanning the driving frequency of an electro-optic amplitude modulator in the range of 2.7–3.2 GHz at steps of 41.7 KHz, we demonstrate a spatial resolution of 0.3 m and a measurement range of over 1 km.

DETERMINATION OF SPECIFIC NEUTRONIC REACTIVITY

DOEpatents

Dessauer, G.

1960-05-10

A method is given for production-line determination of the specific neutronic reactivity of such objects as individual nuclear fuel or neutron absorber elements and is notable for rapidity and apparatus simplicity. The object is incorporated in a slightly sub-critical chain fission reactive assembly having a discrete neutron source, thereby establishing a K/sub eff/ within the crucial range of 0.95 to 0.995. The range was found to afford, uniquely, flux- transient damped response in a niatter of seconds simultaneously with acceptable analytical sensitivity. The resulting neutron flux measured at a situs spaced from both object and source within the assembly serves as a calibrable indication of said reactivity.

Ground based mobile isotopic methane measurements in the Front Range, Colorado

NASA Astrophysics Data System (ADS)

Vaughn, B. H.; Rella, C.; Petron, G.; Sherwood, O.; Mielke-Maday, I.; Schwietzke, S.

2014-12-01

Increased development of unconventional oil and gas resources in North America has given rise to attempts to monitor and quantify fugitive emissions of methane from the industry. Emission estimates of methane from oil and gas basins can vary significantly from one study to another as well as from EPA or State estimates. New efforts are aimed at reconciling bottom-up, or inventory-based, emission estimates of methane with top-down estimates based on atmospheric measurements from aircraft, towers, mobile ground-based vehicles, and atmospheric models. Attributing airborne measurements of regional methane fluxes to specific sources is informed by ground-based measurements of methane. Stable isotopic measurements (δ13C) of methane help distinguish between emissions from the O&G industry, Confined Animal Feed Operations (CAFO), and landfills, but analytical challenges typically limit meaningful isotopic measurements to individual point sampling. We are developing a toolbox to use δ13CH4 measurements to assess the partitioning of methane emissions for regions with multiple methane sources. The method was applied to the Denver-Julesberg Basin. Here we present data from continuous isotopic measurements obtained over a wide geographic area by using MegaCore, a 1500 ft. tube that is constantly filled with sample air while driving, then subsequently analyzed at slower rates using cavity ring down spectroscopy (CRDS). Pressure, flow and calibration are tightly controlled allowing precise attribution of methane enhancements to their point of collection. Comparisons with point measurements are needed to confirm regional values and further constrain flux estimates and models. This effort was made in conjunction with several major field campaigns in the Colorado Front Range in July-August 2014, including FRAPPÉ (Front Range Air Pollution and Photochemistry Experiment), DISCOVER-AQ, and the Air Water Gas NSF Sustainability Research Network at the University of Colorado.

Development of a chemical source apportionment decision support framework for lake catchment management.

PubMed

Comber, Sean D W; Smith, Russell; Daldorph, Peter; Gardner, Michael J; Constantino, Carlos; Ellor, Brian

2018-05-01

Increasing pressures on natural resources has led to the adoption of water quality standards to protect ecological and human health. Lakes and reservoirs are particularly vulnerable to pressure on water quality owing to long residence times compared with rivers. This has raised the question of how to determine and to quantify the sources of priority chemicals (e.g. nutrients, persistent organic pollutants and metals) so that suitable measures can be taken to address failures to comply with regulatory standards. Contaminants enter lakes waters from a range of diffuse and point sources. Decision support tools and models are essential to assess the relative magnitudes of these sources and to estimate the impacts of any programmes of measures. This paper describes the development and testing of the Source Apportionment Geographical Information System (SAGIS) for future management of 763 lakes in England and Wales. The model uses readily available national data sets to estimate contributions of a number of key chemicals including nutrients (nitrogen and phosphorus), metals (copper, zinc, cadmium, lead, mercury and nickel) and organic chemicals (Polynuclear Aromatic Hydrocarbons) from multiple sector sources. Lake-specific sources are included (groundbait from angling and bird faeces) and hydrology associated with pumped inputs and abstraction. Validation data confirms the efficacy of the model to successfully predicted seasonal patterns of all types of contaminant concentrations under a number of hydrological scenarios. Such a tool has not been available on a national scale previously for such a wide range of chemicals and is currently being used to assist with future river basin planning. Copyright © 2017 Elsevier B.V. All rights reserved.

Magnetoencephalographic accuracy profiles for the detection of auditory pathway sources.

PubMed

Bauer, Martin; Trahms, Lutz; Sander, Tilmann

2015-04-01

The detection limits for cortical and brain stem sources associated with the auditory pathway are examined in order to analyse brain responses at the limits of the audible frequency range. The results obtained from this study are also relevant to other issues of auditory brain research. A complementary approach consisting of recordings of magnetoencephalographic (MEG) data and simulations of magnetic field distributions is presented in this work. A biomagnetic phantom consisting of a spherical volume filled with a saline solution and four current dipoles is built. The magnetic fields outside of the phantom generated by the current dipoles are then measured for a range of applied electric dipole moments with a planar multichannel SQUID magnetometer device and a helmet MEG gradiometer device. The inclusion of a magnetometer system is expected to be more sensitive to brain stem sources compared with a gradiometer system. The same electrical and geometrical configuration is simulated in a forward calculation. From both the measured and the simulated data, the dipole positions are estimated using an inverse calculation. Results are obtained for the reconstruction accuracy as a function of applied electric dipole moment and depth of the current dipole. We found that both systems can localize cortical and subcortical sources at physiological dipole strength even for brain stem sources. Further, we found that a planar magnetometer system is more suitable if the position of the brain source can be restricted in a limited region of the brain. If this is not the case, a helmet-shaped sensor system offers more accurate source estimation.

Emittance of positron beams produced in intense laser plasma interaction

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

Chen Hui; Hazi, A.; Link, A.

2013-01-15

The first measurement of the emittance of intense laser-produced positron beams has been made. The emittance values were derived through measurements of positron beam divergence and source size for different peak positron energies under various laser conditions. For one of these laser conditions, we used a one dimensional pepper-pot technique to refine the emittance value. The laser-produced positrons have a geometric emittance between 100 and 500 mm{center_dot}mrad, comparable to the positron sources used at existing accelerators. With 10{sup 10}-10{sup 12} positrons per bunch, this low emittance beam, which is quasi-monoenergetic in the energy range of 5-20 MeV, may be usefulmore » as an alternative positron source for future accelerators.« less

An environmental-level, real-time, pulsed photon dosemeter.

PubMed

Olsher, R H; Frymire, A; Gregoire, T

2005-01-01

Radiation sources producing short pulses of photon radiation are widespread. Such sources include electron linear accelerators and field emission impulse generators. It is often desirable to measure leakage and skyshine radiation for these sources in real time and at environmental levels as low as 0.02 microSv per pulse. This note provides an overview of the design and performance of a commercial, real-time, pulsed photon dosemeter (PPD) capable of single-pulse dose measurements over the range from 0.02 to 20 microSv. The PPD may also be operated in a multiple-pulse mode that integrates the dose from a train of pulses over a 3 s period. A pulse repetition rate of up to 300 Hz is accommodated.

Approach for measuring the chemistry of individual particles in the size range critical for cloud formation.

PubMed

Zauscher, Melanie D; Moore, Meagan J K; Lewis, Gregory S; Hering, Susanne V; Prather, Kimberly A

2011-03-15

Aerosol particles, especially those ranging from 50 to 200 nm, strongly impact climate by serving as nuclei upon which water condenses and cloud droplets form. However, the small number of analytical methods capable of measuring the composition of particles in this size range, particularly at the individual particle level, has limited our knowledge of cloud condensation nuclei (CCN) composition and hence our understanding of aerosols effect on climate. To obtain more insight into particles in this size range, we developed a method which couples a growth tube (GT) to an ultrafine aerosol time-of-flight mass spectrometer (UF-ATOFMS), a combination that allows in situ measurements of the composition of individual particles as small as 38 nm. The growth tube uses water to grow particles to larger sizes so they can be optically detected by the UF-ATOFMS, extending the size range to below 100 nm with no discernible changes in particle composition. To gain further insight into the temporal variability of aerosol chemistry and sources, the GT-UF-ATOFMS was used for online continuous measurements over a period of 3 days.

Inducing in situ, nonlinear soil response applying an active source

USGS Publications Warehouse

Johnson, P.A.; Bodin, P.; Gomberg, J.; Pearce, F.; Lawrence, Z.; Menq, F.-Y.

2009-01-01

[1] It is well known that soil sites have a profound effect on ground motion during large earthquakes. The complex structure of soil deposits and the highly nonlinear constitutive behavior of soils largely control nonlinear site response at soil sites. Measurements of nonlinear soil response under natural conditions are critical to advancing our understanding of soil behavior during earthquakes. Many factors limit the use of earthquake observations to estimate nonlinear site response such that quantitative characterization of nonlinear behavior relies almost exclusively on laboratory experiments and modeling of wave propagation. Here we introduce a new method for in situ characterization of the nonlinear behavior of a natural soil formation using measurements obtained immediately adjacent to a large vibrator source. To our knowledge, we are the first group to propose and test such an approach. Employing a large, surface vibrator as a source, we measure the nonlinear behavior of the soil by incrementally increasing the source amplitude over a range of frequencies and monitoring changes in the output spectra. We apply a homodyne algorithm for measuring spectral amplitudes, which provides robust signal-to-noise ratios at the frequencies of interest. Spectral ratios are computed between the receivers and the source as well as receiver pairs located in an array adjacent to the source, providing the means to separate source and near-source nonlinearity from pervasive nonlinearity in the soil column. We find clear evidence of nonlinearity in significant decreases in the frequency of peak spectral ratios, corresponding to material softening with amplitude, observed across the array as the source amplitude is increased. The observed peak shifts are consistent with laboratory measurements of soil nonlinearity. Our results provide constraints for future numerical modeling studies of strong ground motion during earthquakes.

In-duct identification of fluid-borne source with high spatial resolution

NASA Astrophysics Data System (ADS)

Heo, Yong-Ho; Ih, Jeong-Guon; Bodén, Hans

2014-11-01

Source identification of acoustic characteristics of in-duct fluid machinery is required for coping with the fluid-borne noise. By knowing the acoustic pressure and particle velocity field at the source plane in detail, the sound generation mechanism of a fluid machine can be understood. The identified spatial distribution of the strength of major radiators would be useful for the low noise design. Conventional methods for measuring the source in a wide duct have not been very helpful in investigating the source properties in detail because their spatial resolution is improper for the design purpose. In this work, an inverse method to estimate the source parameters with a high spatial resolution is studied. The theoretical formulation including the evanescent modes and near-field measurement data is given for a wide duct. After validating the proposed method to a duct excited by an acoustic driver, an experiment on a duct system driven by an air blower is conducted in the presence of flow. A convergence test for the evanescent modes is performed to find the necessary number of modes to regenerate the measured pressure field precisely. By using the converged modal amplitudes, very-close near-field pressure to the source is regenerated and compared with the measured pressure, and the maximum error was -16.3 dB. The source parameters are restored from the converged modal amplitudes. Then, the distribution of source parameters on the driver and the blower is clearly revealed with a high spatial resolution for kR<1.84 in which range only plane waves can propagate to far field in a duct. Measurement using a flush mounted sensor array is discussed, and the removal of pure radial modes in the modeling is suggested.

Source apportionment of atmospheric ammonia before, during, and after the 2014 APEC summit in Beijing using stable nitrogen isotope signatures

NASA Astrophysics Data System (ADS)

Chang, Yunhua; Liu, Xuejun; Deng, Congrui; Dore, Anthony J.; Zhuang, Guoshun

2016-09-01

Stable nitrogen isotope composition (δ15N) offers new opportunities to address the long-standing and ongoing controversy regarding the origins of ambient ammonia (NH3), a vital precursor of PM2.5 (particulate matters with aerodynamic diameter equal or less than 2.5 µm) inorganic components, in the urban atmosphere. In this study, the δ15N values of NH3 samples collected from various sources were constrained using a novel and robust chemical method coupled with standard elemental analysis procedures. Independent of the wide variation in mass concentrations (ranging from 33 (vehicle) to over 6000 (human excreta) µg m-3), different NH3 sources have generally different δ15N values (ranging from -52.0 to -9.6 ‰). Significantly high δ15N values are seen as a characteristic feature of all vehicle-derived NH3 samples (-14.2 ± 2.8 ‰), which can be distinguished from other sources emitted at environmental temperature (-29.1 ± 1.7, -37.8 ± 3.6, and -50.0 ± 1.8 ‰ for livestock, waste, and fertilizer, respectively). The isotope δ15N signatures for a range of NH3 emission sources were used to evaluate the contributions of the different sources within measured ambient NH3 in Beijing, using an isotope mixing model (IsoSource). The method was used to quantify the sources of ambient NH3 before, during and after the 2014 Asia-Pacific Economic Cooperation (APEC) summit, when a set of stringent air quality control measures were implemented. Results show that the average NH3 concentrations (the overall contributions of traffic, waste, livestock, and fertilizer) during the three periods were 9.1 (20.3, 28.3, 23.6, and 27.7 %), 7.3 (8.8, 24.9, 14.3, and 52.0 %), and 12.7 (29.4, 23.6, 31.7, and 15.4 %) µg m-3, respectively, representing a 20.0 % decrease first and then a 74.5 % increase in overall NH3 mass concentrations. During (after) the summit, the contributions of traffic, waste, livestock, and fertilizer decreased (increased) by 56.7 (234.2), 12.0 (-5.0), 39.4 (120.8), and -87.7 % (-70.5 %) when compared with periods before (during) the summit, respectively, signifying that future NH3 control efforts in megacities like Beijing should prioritize traffic sector as well as livestock breeding. The results show that isotope ratio measurements of NH3 to be a valuable tool to quantify the atmospheric sources of NH3 in urban atmospheres.

Isotopic Signatures for Source Apportionment of Ammonia in Urban Atmosphere

NASA Astrophysics Data System (ADS)

Chang, Y.; Liu, X.

2016-12-01

Stable nitrogen isotope composition (δ15N) offers new opportunities to address the long-standing and ongoing controversy regarding the origins of ambient ammonia (NH3), a vital precursor of PM2.5 inorganic components, in the urban atmosphere. In this study, the δ15N values of NH3 samples collected from various sources were constrained using a novel and robust chemical method coupled with standard elemental analysis procedures. Independent of the wide variation in mass concentrations (ranging from 33 (vehicle) to over 6000 (human excreta) μg m-3), different NH3 sources have generally different δ15N values (ranging from -52.0 to -9.6‰). Significantly high δ15N values are seen as a characteristic feature of all vehicle-derived NH3 samples (-14.2±2.8‰), which can be distinguished from other sources emitted at environmental temperature (-29.1±1.7, -37.8±3.6, and -50.0±1.8‰ for livestock, waste, and fertilizer, respectively). The isotope δ15N signatures for a range of NH3 emission sources were used to evaluate the contributions of the different sources within measured ambient NH3 in Beijing, using an isotope mixing model (IsoSource). The method was used to quantify the sources of ambient NH3 before, during and after the 2014 APEC summit, when a set of stringent air quality control measures were implemented. Results show that the average NH3 concentrations (the overall contributions of traffic, waste, livestock, and fertilizer) during the three periods were 9.1 (15.1, 31.2, 23.7, and 30.0%), 7.3 (8.8, 24.9, 14.3, and 52.0%), and 12.7 (29.4, 23.6, 31.7, and 15.4%) μg m-3, respectively, representing a 20.0% decrease first and then a 74.5% increase in overall NH3 mass concentrations. During (after) the summit, the contributions of traffic, waste, livestock, and fertilizer decreased (increased) by 58.7 (234.2), 0.9 (-5.0), 41.0 (120.8), and -87.6% (-70.5%) when compared with periods before (during) the summit, respectively, signifying that future NH3 control efforts in mega-cities like Beijing should prioritize traffic sector as well as livestock breeding. The results show that isotope ratio measurements of NH3 to be a valuable tool to quantify the atmospheric sources of NH3 in urban atmospheres.

A digital wide range neutron flux measuring system for HL-2A

NASA Astrophysics Data System (ADS)

Yuan, Chen; Wu, Jun; Yin, Zejie

2017-08-01

To achieve wide-range, high-integration, and real-time performance on the neutron flux measurement on the HL-2A tokamak, a digital neutron flux measuring (DNFM) system based on the peripheral component interconnection (PCI) eXtension for Instrumentation express (PXIe) bus was designed. This system comprises a charge-sensitive preamplifier and a field programmable gate array (FPGA)-based main electronics plug-in. The DNFM totally covers source-range and intermediate-range neutron flux measurements, and increases system integration by a large margin through joining the pulse-counting mode and Campbell mode. Meanwhile, the neutron flux estimation method based on pulse piling proportions is able to choose and switch measuring modes in accordance with current flux, and this ensures the accuracy of measurements when the neutron flux changes suddenly. It has been demonstrated by simulated signals that the DNFM enhances the full-scale measuring range up to 1.9 × 108 cm-2 s-1, with relative error below 6.1%. The DNFM has been verified to provide a high temporal sensitivity at 10 ms time intervals on a single fission chamber on HL-2A. Contributed paper, published as part of the Proceedings of the 3rd Domestic Electromagnetic Plasma Diagnostics Workshop, September 2016, Hefei, China.

Methanol Production by a Broad Phylogenetic Array of Marine Phytoplankton.

PubMed

Mincer, Tracy J; Aicher, Athena C

2016-01-01

Methanol is a major volatile organic compound on Earth and serves as an important carbon and energy substrate for abundant methylotrophic microbes. Previous geochemical surveys coupled with predictive models suggest that the marine contributions are exceedingly large, rivaling terrestrial sources. Although well studied in terrestrial ecosystems, methanol sources are poorly understood in the marine environment and warrant further investigation. To this end, we adapted a Purge and Trap Gas Chromatography/Mass Spectrometry (P&T-GC/MS) method which allowed reliable measurements of methanol in seawater and marine phytoplankton cultures with a method detection limit of 120 nanomolar. All phytoplankton tested (cyanobacteria: Synechococcus spp. 8102 and 8103, Trichodesmium erythraeum, and Prochlorococcus marinus), and Eukarya (heterokont diatom: Phaeodactylum tricornutum, coccolithophore: Emiliania huxleyi, cryptophyte: Rhodomonas salina, and non-diatom heterokont: Nannochloropsis oculata) produced methanol, ranging from 0.8-13.7 micromolar in culture and methanol per total cellular carbon were measured in the ranges of 0.09-0.3%. Phytoplankton culture time-course measurements displayed a punctuated production pattern with maxima near early stationary phase. Stabile isotope labeled bicarbonate incorporation experiments confirmed that methanol was produced from phytoplankton biomass. Overall, our findings suggest that phytoplankton are a major source of methanol in the upper water column of the world's oceans.

Methanol Production by a Broad Phylogenetic Array of Marine Phytoplankton

PubMed Central

Mincer, Tracy J.; Aicher, Athena C.

2016-01-01

Methanol is a major volatile organic compound on Earth and serves as an important carbon and energy substrate for abundant methylotrophic microbes. Previous geochemical surveys coupled with predictive models suggest that the marine contributions are exceedingly large, rivaling terrestrial sources. Although well studied in terrestrial ecosystems, methanol sources are poorly understood in the marine environment and warrant further investigation. To this end, we adapted a Purge and Trap Gas Chromatography/Mass Spectrometry (P&T-GC/MS) method which allowed reliable measurements of methanol in seawater and marine phytoplankton cultures with a method detection limit of 120 nanomolar. All phytoplankton tested (cyanobacteria: Synechococcus spp. 8102 and 8103, Trichodesmium erythraeum, and Prochlorococcus marinus), and Eukarya (heterokont diatom: Phaeodactylum tricornutum, coccolithophore: Emiliania huxleyi, cryptophyte: Rhodomonas salina, and non-diatom heterokont: Nannochloropsis oculata) produced methanol, ranging from 0.8–13.7 micromolar in culture and methanol per total cellular carbon were measured in the ranges of 0.09–0.3%. Phytoplankton culture time-course measurements displayed a punctuated production pattern with maxima near early stationary phase. Stabile isotope labeled bicarbonate incorporation experiments confirmed that methanol was produced from phytoplankton biomass. Overall, our findings suggest that phytoplankton are a major source of methanol in the upper water column of the world’s oceans. PMID:26963515

Application of time-division-multiplexed lasers for measurements of gas temperature and CH4 and H2O concentrations at 30 kHz in a high-pressure combustor.

PubMed

Caswell, Andrew W; Kraetschmer, Thilo; Rein, Keith; Sanders, Scott T; Roy, Sukesh; Shouse, Dale T; Gord, James R

2010-09-10

Two time-division-multiplexed (TDM) sources based on fiber Bragg gratings were applied to monitor gas temperature, H(2)O mole fraction, and CH(4) mole fraction using line-of-sight absorption spectroscopy in a practical high-pressure gas turbine combustor test article. Collectively, the two sources cycle through 14 wavelengths in the 1329-1667 nm range every 33 μs. Although it is based on absorption spectroscopy, this sensing technology is fundamentally different from typical diode-laser-based absorption sensors and has many advantages. Specifically, the TDM lasers allow efficient, flexible acquisition of discrete-wavelength information over a wide spectral range at very high speeds (typically 30 kHz) and thereby provide a multiplicity of precise data at high speeds. For the present gas turbine application, the TDM source wavelengths were chosen using simulated temperature-difference spectra. This approach is used to select TDM wavelengths that are near the optimum values for precise temperature and species-concentration measurements. The application of TDM lasers for other measurements in high-pressure, turbulent reacting flows and for two-dimensional tomographic reconstruction of the temperature and species-concentration fields is also forecast.

Vertical coherence and forward scattering from the sea surface and the relation to the directional wave spectrum.

PubMed

Dahl, Peter H; Plant, William J; Dall'Osto, David R

2013-09-01

Results of an experiment to measure vertical spatial coherence from acoustic paths interacting once with the sea surface but at perpendicular azimuth angles are presented. The measurements were part of the Shallow Water 2006 program that took place off the coast of New Jersey in August 2006. An acoustic source, frequency range 6-20 kHz, was deployed at depth 40 m, and signals were recorded on a 1.4 m long vertical line array centered at depth 25 m and positioned at range 200 m. The vertical array consisted of four omni-directional hydrophones and vertical coherences were computed between pairs of these hydrophones. Measurements were made over four source-receiver bearing angles separated by 90°, during which sea surface conditions remained stable and characterized by a root-mean-square wave height of 0.17 m and a mixture of swell and wind waves. Vertical coherences show a statistically significant difference depending on source-receiver bearing when the acoustic frequency is less than about 12 kHz, with results tending to fade at higher frequencies. This paper presents field observations and comparisons of these observations with two modeling approaches, one based on bistatic forward scattering and the other on a rough surface parabolic wave equation utilizing synthetic sea surfaces.

Geoscience Laser Ranging System design and performance predictions

NASA Technical Reports Server (NTRS)

Anderson, Kent L.

1991-01-01

The Geoscience Laser System (GLRS) will be a high-precision distance-measuring instrument planned for deployment on the EOS-B platform. Its primary objectives are to perform ranging measurements to ground targets to monitor crustal deformation and tectonic plate motions, and nadir-looking altimetry to determine ice sheet thicknesses, surface topography, and vertical profiles of clouds and aerosols. The system uses a mode-locked, 3-color Nd:YAG laser source, a Microchannel Plate-PMT for absolute time-of-flight (TOF) measurement (at 532 nm), a streak camera for TOF 2-color dispersion measurement (532 nm and 355 nm), and a Si avalanche photodiode for altimeter waveform detection (1064 nm). The performance goals are to make ranging measurements to ground targets with about 1 cm accuracy, and altimetry height measurements over ice with 10 cm accuracy. This paper presents an overview of the design concept developed during a phase B study. System engineering issues and trade studies are discussed, with particular attention to error budgets and performance predictions.

SU-G-201-16: Thermal Imaging in Source Visualization and Radioactivity Measurement for High Dose Rate Brachytherapy

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

Zhu, X; Lei, Y; Zheng, D

2016-06-15

Purpose: High Dose Rate (HDR) brachytherapy poses a special challenge to radiation safety and quality assurance (QA) due to its high radioactivity, and it is thus critical to verify the HDR source location and its radioactive strength. This study demonstrates a new method for measuring HDR source location and radioactivity utilizing thermal imaging. A potential application would relate to HDR QA and safety improvement. Methods: Heating effects by an HDR source were studied using Finite Element Analysis (FEA). Thermal cameras were used to visualize an HDR source inside a plastic applicator made of polyvinylidene difluoride (PVDF). Using different source dwellmore » times, correlations between the HDR source strength and heating effects were studied, thus establishing potential daily QA criteria using thermal imaging Results: For an Ir1?2 source with a radioactivity of 10 Ci, the decay-induced heating power inside the source is ∼13.3 mW. After the HDR source was extended into the PVDF applicator and reached thermal equilibrium, thermal imaging visualized the temperature gradient of 10 K/cm along the PVDF applicator surface, which agreed with FEA modeling. For Ir{sup 192} source activities ranging from 4.20–10.20 Ci, thermal imaging could verify source activity with an accuracy of 6.3% with a dwell time of 10 sec, and an accuracy of 2.5 % with 100 sec. Conclusion: Thermal imaging is a feasible tool to visualize HDR source dwell positions and verify source integrity. Patient safety and treatment quality will be improved by integrating thermal measurements into HDR QA procedures.« less

Heavy Ion Microbeam and Broadbeam Transients in SiGe HBTs

NASA Technical Reports Server (NTRS)

Pellish, Jonathan A.; Reed, Robert A.; McMorrow, Dale; Vizkelethy, Gyorgy; Dodd, Paul E.; Ferlet-Cavrois, Veronique; Baggio, Jacques; Paillet, Philippe; Duhamel, Olivier; Phillips, Stanley D.;

Comparison of measured and modeled BRDF of natural targets

NASA Astrophysics Data System (ADS)

Boucher, Yannick; Cosnefroy, Helene; Petit, Alain D.; Serrot, Gerard; Briottet, Xavier

1999-07-01

The Bidirectional Reflectance Distribution Function (BRDF) plays a major role to evaluate or simulate the signatures of natural and artificial targets in the solar spectrum. A goniometer covering a large spectral and directional domain has been recently developed by the ONERA/DOTA. It was designed to allow both laboratory and outside measurements. The spectral domain ranges from 0.40 to 0.95 micrometer, with a resolution of 3 nm. The geometrical domain ranges 0 - 60 degrees for the zenith angle of the source and the sensor, and 0 - 180 degrees for the relative azimuth between the source and the sensor. The maximum target size for nadir measurements is 22 cm. The spatial target irradiance non-uniformity has been evaluated and then used to correct the raw measurements. BRDF measurements are calibrated thanks to a spectralon reference panel. Some BRDF measurements performed on sand and short grass and are presented here. Eight bidirectional models among the most popular models found in the literature have been tested on these measured data set. A code fitting the model parameters to the measured BRDF data has been developed. The comparative evaluation of the model performances is carried out, versus different criteria (root mean square error, root mean square relative error, correlation diagram . . .). The robustness of the models is evaluated with respect to the number of BRDF measurements, noise and interpolation.

An experimental evaluation of monochromatic x-ray beam position monitors at diamond light source

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

Bloomer, Chris, E-mail: chris.bloomer@diamond.ac.uk; Rehm, Guenther; Dolbnya, Igor P.

Maintaining the stability of the X-ray beam relative to the sample point is of paramount importance for beamlines and users wanting to perform cutting-edge experiments. The ability to detect, and subsequently compensate for, variations in X-ray beam position with effective diagnostics has multiple benefits: a reduction in commissioning and start-up time, less ‘down-time’, and an improvement in the quality of acquired data. At Diamond Light Source a methodical evaluation of a selection of monochromatic X-ray Beam Position Monitors (XBPMs), using a range of position detection techniques, and from a range of suppliers, was carried out. The results of these experimentsmore » are presented, showing the measured RMS noise on the position measurement of each device for a given flux, energy, beam size, and bandwidth. A discussion of the benefits and drawbacks of each of the various devices and techniques is also included.« less

Space shuttle electromagnetic environment experiment. Phase A: Definition study

NASA Technical Reports Server (NTRS)

Haber, F.; Showers, R. M.; Kocher, C.; Forrest, L. A., Jr.

1976-01-01

Methods for carrying out measurements of earth electromagnetic environment using the space shuttle as a measurement system platform are herein reported. The goal is to provide means for mapping intentional and nonintentional emitters on earth in the frequency range 0.4 to 40 GHz. A survey was made of known emitters using available data from national and international regulatory agencies, and from industry sources. The spatial distribution of sources, power levels, frequencies, degree of frequency re-use, etc., found in the survey, are here presented. A concept is developed for scanning the earth using a directive antenna whose beam is made to rotate at a fixed angle relative to the nadir; the illuminated area swept by the beam is of the form of cycloidal annulus over a sphere. During the beam's sojourn over a point, the receiver sweeps in frequency over ranges in the order of octave width using sweeping filter bandwidths sufficient to give stable readings.

Laser induced fluorescence in algae: A new technique for remote detection

NASA Technical Reports Server (NTRS)

Friedman, E. J.; Hickman, G. D.

1972-01-01

Measurements of the absorption and fluorescence spectra were obtained for four various types of marine and fresh water algae using a pulsed N2/Ne dye laser as the source of excitation. The absorption maxima for the algae ranged from 420 to 675 nm, while their fluorescent spectra ranged from 580 to 685 nm. It appears feasible that various algal species can be identified by detection of their fluorescent signatures using a tunable laser as the excitation source. However, if one is concerned only with detection of chlorophyll a, the optimum excitation is approximately 600 + 50 nm while detection is at 685 nm. An analysis of both calculations and laboratory results indicates that it should be feasible to measure chlorophyll a in concentrations as low as 1.0 mg/m3 using a 100 kW peak pulsed laser from an altitude of 500 meters.

Comparison of gate and drain current detection of hydrogen at room temperature with AlGaN /GaN high electron mobility transistors

NASA Astrophysics Data System (ADS)

Wang, Hung-Ta; Kang, B. S.; Ren, F.; Fitch, R. C.; Gillespie, J. K.; Moser, N.; Jessen, G.; Jenkins, T.; Dettmer, R.; Via, D.; Crespo, A.; Gila, B. P.; Abernathy, C. R.; Pearton, S. J.

2005-10-01

Pt-gated AlGaN /GaN high electron mobility transistors can be used as room-temperature hydrogen gas sensors at hydrogen concentrations as low as 100ppm. A comparison of the changes in drain and gate current-voltage (I-V) characteristics with the introduction of 500ppm H2 into the measurement ambient shows that monitoring the change in drain-source current provides a wider gate voltage operation range for maximum detection sensitivity and higher total current change than measuring the change in gate current. However, over a narrow gate voltage range, the relative sensitivity of detection by monitoring the gate current changes is up to an order of magnitude larger than that of drain-source current changes. In both cases, the changes are fully reversible in <2-3min at 25°C upon removal of the hydrogen from the ambient.

Mass attenuation coefficients in the range 3.8⩽E⩽11 keV, K fluorescence yield and Kβ/Kα relative X-ray emission rate for Ti, V, Fe, Co, Ni, Cu and Zn measured with a tunable monochromatic X-ray source

NASA Astrophysics Data System (ADS)

Ménesguen, Y.; Lépy, M.-C.

2010-08-01

This work presents new measurements of mass attenuation coefficients in the range 3.8⩽E⩽11 keV, K-absorption jump-ratios, Kα and Kβ fluorescence yields for Ti, V, Fe, Co, Ni, Cu and Zn. We use the experimental facility SOLEX, a tunable monochromatic X-ray source combined with an energy-dispersive high-purity germanium detector. The results are compared with theoretical values as well as with other experimental data and show a relatively good agreement. However, the derived K-jump-ratios appear larger than those widely used in the XCOM database. The Kα and Kβ fluorescence yields and the corresponding relative emission rates Kβ/Kα are also derived, which was made possible by the use of energy-dispersive detectors with good spectral resolution.

Dynamic measurements of thermophysical properties of metals and alloys at high temperatures by subsecond pulse heating techniques

NASA Technical Reports Server (NTRS)

Cezairliyan, Ared

1993-01-01

Rapid (subsecond) heating techniques developed at the National Institute of Standards and Technology for the measurements of selected thermophysical and related properties of metals and alloys at high temperatures (above 1000 C) are described. The techniques are based on rapid resistive self-heating of the specimen from room temperature to the desired high temperature in short times and measuring the relevant experimental quantities, such as electrical current through the specimen, voltage across the specimen, specimen temperature, length, etc., with appropriate time resolution. The first technique, referred to as the millisecond-resolution technique, is for measurements on solid metals and alloys in the temperature range 1000 C to the melting temperature of the specimen. It utilizes a heavy battery bank for the energy source, and the total heating time of the specimen is typically in the range of 100-1000 ms. Data are recorded digitally every 0.5 ms with a full-scale resolution of about one part in 8000. The properties that can be measured with this system are as follows: specific heat, enthalpy, thermal expansion, electrical resistivity, normal spectral emissivity, hemispherical total emissivity, temperature and energy of solid-solid phase transformations, and melting temperature (solidus). The second technique, referred to as the microsecond-resolution technique, is for measurements on liquid metals and alloys in the temperature range 1200 to 6000 C. It utilizes a capacitor bank for the energy source, and the total heating time of the specimen is typically in the range 50-500 micro-s. Data are recorded digitally every 0.5 micro-s with a full-scale resolution of about one part in 4000. The properties that can be measured with this system are: melting temperature (solidus and liquidus), heat of fusion, specific heat, enthalpy, and electrical resistivity. The third technique is for measurements of the surface tension of liquid metals and alloys at their melting temperature. It utilizes a modified millisecond-resolution heating system designed for use in a microgravity environment.

Damping mechanisms in chemically vapor deposited SiC fibers

NASA Technical Reports Server (NTRS)

Dicarlo, James A.; Goldsby, Jon C.

1993-01-01

Evaluating the damping of reinforcement fibers is important for understanding their microstructures and the vibrational response of their structural composites. In this study the damping capacities of two types of chemically vapor deposited silicon carbide fibers were measured from -200 C to as high as 800 C. Measurements were made at frequencies in the range 50 to 15000 Hz on single cantilevered fibers. At least four sources were identified which contribute to fiber damping, the most significant being thermoelastic damping and grain boundary sliding. The mechanisms controlling all sources and their potential influence on fiber and composite performance are discussed.

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

Jones, J E; Smith, J T; Mathis, M V

Based on the limited measurements and the attempts to activate the high voltage power supply, the Source Range Monitor which includes NI-AMP-2 is not operating. Since there appears to be an excessive load on the high voltage, it appears that either the detector or cable is defective. However, TDR measurements did not indicate a significant problem with the cable using low level test signals.

Partitioning autotrophic and heterotrophic respiration at Howland Forest

NASA Astrophysics Data System (ADS)

Carbone, Mariah; Hollinger, Dave; Davidson, Eric; Savage, Kathleen; Hughes, Holly

2015-04-01

Terrestrial ecosystem respiration is the combined flux of CO2 to the atmosphere from above- and below-ground, plant (autotrophic) and microbial (heterotrophic) sources. Flux measurements alone (e.g., from eddy covariance towers or soil chambers) cannot distinguish the contributions from these sources, which may change seasonally and respond differently to temperature and moisture. The development of improved process-based models that can predict how plants and microbes respond to changing environmental conditions (on seasonal, interannual, or decadal timescales) requires data from field observations and experiments to distinguish among these respiration sources. We tested the viability of partitioning of soil and ecosystem respiration into autotrophic and heterotrophic components with different approaches at the Howland Forest in central Maine, USA. These include an experimental manipulation using the classic root trenching approach and targeted ∆14CO2 measurements. For the isotopic measurements, we used a two-end member mass balance approach to determine the fraction of soil respiration from autotrophic and heterotrophic sources. When summed over the course of the growing season, the trenched chamber flux (heterotrophic) accounted for 53 ± 2% of the total control chamber flux. Over the four different 14C sampling periods, the heterotrophic component ranged from 35-55% and the autotrophic component ranges 45-65% of the total flux. Next steps will include assessing the value of the flux partitioning for constraining a simple ecosystem model using a model-data fusion approach to reduce uncertainties in estimates of NPP and simulation of future soil C stocks and fluxes.

Measuring H2O and CO2 Emissions in the Mud Volcano region of Yellowstone using Open Path FTIR

NASA Astrophysics Data System (ADS)

Moyer, D. K.; Sealing, C. R.; Carn, S. A.; Vanderkluysen, L.

2017-12-01

Magma degassing is an important factor in many aspects of monitoring active volcanic zones and mitigating associated hazards. The monitoring of these emissions in concentration, flux, and species ratios is important for detecting signs of unrest as well as understanding the natural cycle and budget of volatile species. However, standard gas measurement methods suffer from either low temporal resolution (e.g., direct sampling of fumaroles) or are limited to measuring a small range of species (e.g., MiniDOAS, MultiGAS). In order to establish a carbon budget of active gas sources at a volcano with a dynamic hydrothermal system, we carried out a survey of mud pots and fumaroles at Yellowstone National Park using Open-Path Fourier Transform Infrared Spectroscopy, or OP-FTIR, which allows for a temporal resolution as low as one measurement every 10 seconds. We placed an active infrared (IR) source behind the target gas plume and identified gas species from the presence of their absorption feature in measured spectra in the 2.5 to 25 µm range. From these, we derived pathlength concentrations for a wide range of gases, including: water vapor, carbon dioxide, and methane. During our September 2016 campaign in the Mud Volcano thermal area, we measured CO2 concentrations of 400 ppm in emissions from the Churning Cauldron acid-sulfate mud pot, with an H2O/CO2 ratio of 8; at Sulphur Cauldron and One Hundred Springs Plain, CO2 concentrations reached 200 ppm above background atmospheric values. We derived a CO2 flux of 8.15 T/d, 0.43 T/d and .00025 T/d, respectively, at these three acid-sulfate sources, within range of gas channeling-based estimates from the late 1990s. Previous accumulation chamber studies estimate the CO2 soil diffuse degassing in the Mud Volcano thermal region at 283.15 T/d, indicating that mud pots are minor contributors of CO2 emissions in this area, representing 3% of diffuse emissions. Due to the high acquisition rate and the abundance of water droplets in the plume, spectra were too noisy to reliably detect methane at these locations. Future work will focus on the measurement of trace gases at these same locations by increasing the acquisition time.

Experimental Results of Underwater Cooperative Source Localization Using a Single Acoustic Vector Sensor

PubMed Central

Felisberto, Paulo; Rodriguez, Orlando; Santos, Paulo; Ey, Emanuel; Jesus, Sérgio M.

2013-01-01

This paper aims at estimating the azimuth, range and depth of a cooperative broadband acoustic source with a single vector sensor in a multipath underwater environment, where the received signal is assumed to be a linear combination of echoes of the source emitted waveform. A vector sensor is a device that measures the scalar acoustic pressure field and the vectorial acoustic particle velocity field at a single location in space. The amplitudes of the echoes in the vector sensor components allow one to determine their azimuth and elevation. Assuming that the environmental conditions of the channel are known, source range and depth are obtained from the estimates of elevation and relative time delays of the different echoes using a ray-based backpropagation algorithm. The proposed method is tested using simulated data and is further applied to experimental data from the Makai'05 experiment, where 8–14 kHz chirp signals were acquired by a vector sensor array. It is shown that for short ranges, the position of the source is estimated in agreement with the geometry of the experiment. The method is low computational demanding, thus well-suited to be used in mobile and light platforms, where space and power requirements are limited. PMID:23857257

Experimental assessment of theory for refraction of sound by a shear layer

NASA Technical Reports Server (NTRS)

Schlinker, R. H.; Amiet, R. K.

1978-01-01

The refraction angle and amplitude changes associated with sound transmission through a circular, open-jet shear layer were studied in a 0.91 m diameter open jet acoustic research tunnel. Free stream Mach number was varied from 0.1 to 0.4. Good agreement between refraction angle correction theory and experiment was obtained over the test Mach number, frequency and angle measurement range for all on-axis acoustic source locations. For off-axis source positions, good agreement was obtained at a source-to-shear layer separation distance greater than the jet radius. Measureable differences between theory and experiment occurred at a source-to-shear layer separation distance less than one jet radius. A shear layer turbulence scattering experiment was conducted at 90 deg to the open jet axis for the same free stream Mach numbers and axial source locations used in the refraction study. Significant discrete tone spectrum broadening and tone amplitude changes were observed at open jet Mach numbers above 0.2 and at acoustic source frequencies greater than 5 kHz. More severe turbulence scattering was observed for downstream source locations.

Preparation of alpha sources using magnetohydrodynamic electrodeposition for radionuclide metrology.

PubMed

Panta, Yogendra M; Farmer, Dennis E; Johnson, Paula; Cheney, Marcos A; Qian, Shizhi

2010-02-01

Expanded use of nuclear fuel as an energy resource and terrorist threats to public safety clearly require the development of new state-of-the-art technologies and improvement of safety measures to minimize the exposure of people to radiation and the accidental release of radiation into the environment. The precision in radionuclide metrology is currently limited by the source quality rather than the detector performance. Electrodeposition is a commonly used technique to prepare massless radioactive sources. Unfortunately, the radioactive sources prepared by the conventional electrodeposition method produce poor resolution in alpha spectrometric measurements. Preparing radioactive sources with better resolution and higher yield in the alpha spectrometric range by integrating magnetohydrodynamic convection with the conventional electrodeposition technique was proposed and tested by preparing mixed alpha sources containing uranium isotopes ((238)U, (234)U), plutonium ((239)Pu), and americium ((241)Am) for alpha spectrometric determination. The effects of various parameters such as magnetic flux density, deposition current and time, and pH of the sample solution on the formed massless radioactive sources were also experimentally investigated. Copyright 2009 Elsevier Inc. All rights reserved.

High resolution spectroscopic optical coherence tomography in the 900-1100 nm wavelength range

NASA Astrophysics Data System (ADS)

Bizheva, Kostadinka K.; Povazay, Boris; Apolonski, Alexander A.; Unterhuber, Angelika; Hermann, Boris; Sattmann, Harald; Russell, Phillip S. J.; Krausz, Ferenc; Fercher, Adolf F.; Drexler, Wolfgang

2002-06-01

We demonstrate for the first time optical coherence tomography (OCT) in the 900-1100 nm wavelength range. A photonic crystal fiber (PCF) in combination with a sub-15fs Ti:sapphire laser is used to produce an emission spectrum with an optical bandwidth of 35 nm centered at ~1070 nm. Coupling the light from the PCF based source to an optimized free space OCT system results in ~15 micrometers axial resolution in air, corresponding to ~10 micrometers in biological tissue. The near infrared wavelength range around 1100 nm is very attractive for high resolution ophthalmologic OCT imaging of the anterior and posterior eye segment with enhanced penetration. The emission spectrum of the PCF based light source can also be reshaped and tuned to cover the wavelength region around 950-970 nm, where water absorption has a local peak. Therefore, the OCT system described in this paper can also be used for spatially resolved water absorption measurements in non-transparent biological tissue. A preliminary qualitative spectroscopic Oct measurement in D2O and H2 O phantoms is described in this paper.

Fructan content of commonly consumed wheat, rye and gluten-free breads.

PubMed

Whelan, Kevin; Abrahmsohn, Olivia; David, Gondi J P; Staudacher, Heidi; Irving, Peter; Lomer, Miranda C E; Ellis, Peter R

2011-08-01

Fructans are non-digestible carbohydrates with various nutritional properties including effects on microbial metabolism, mineral absorption and satiety. They are present in a range of plant foods, with wheat being an important source. The aim of the present study was to measure the fructan content of a range of wheat, rye and gluten-free breads consumed in the United Kingdom. Fructans were measured in a range of breads using selective enzymic hydrolysis and spectrophotometry based on the AOAC 999.03 method. The breads generally contained low quantities of fructan (0.61-1.94 g/100 g), with rye bread being the richest source (1.94 g/100 g). Surprisingly, gluten-free bread contained similar quantities of fructan (1.00 g/100 g) as other breads. There was wide variation in fructan content between individual brands of granary (0.76-1.09 g/100 g) and gluten-free breads (0.36-1.79 g/100 g). Although they contain only low quantities of fructan, the widespread consumption of bread may make a significant contribution to fructan intakes.

Multiple-Path-Length Optical Absorbance Cell

NASA Technical Reports Server (NTRS)

2001-01-01

An optical absorbance cell that offers a selection of multiple optical path lengths has been developed as part of a portable spectrometric instrument that measures absorption spectra of small samples of water and that costs less than does a conventional, non-portable laboratory spectrometer. The instrument is intended, more specifically, for use in studying colored dissolved organic matter (CDOM) in seawater, especially in coastal regions. Accurate characterization of CDOM is necessary for building bio-optical mathematical models of seawater. The multiple path lengths of the absorption cell afford a wide range of sensitivity needed for measuring the optical absorbances associated with the wide range of concentrations of CDOM observed in nature. The instrument operates in the wavelength range of 370 to 725 nm. The major subsystems of the instrument (see figure) include a color-balanced light source; the absorption cell; a peristaltic pump; a high-precision, low-noise fiber optic spectrometer; and a laptop or other personal computer. A fiber-optic cable transmits light from the source to the absorption cell. Other optical fibers transmit light from the absorption cell to the spectrometer,

Multi-wavelength mid-IR light source for gas sensing

NASA Astrophysics Data System (ADS)

Karioja, Pentti; Alajoki, Teemu; Cherchi, Matteo; Ollila, Jyrki; Harjanne, Mikko; Heinilehto, Noora; Suomalainen, Soile; Viheriälä, Jukka; Zia, Nouman; Guina, Mircea; Buczyński, Ryszard; Kasztelanic, Rafał; Kujawa, Ireneusz; Salo, Tomi; Virtanen, Sami; Kluczyński, Paweł; Sagberg, Hâkon; Ratajczyk, Marcin; Kalinowski, Przemyslaw

2017-02-01

Cost effective multi-wavelength light sources are key enablers for wide-scale penetration of gas sensors at Mid-IR wavelength range. Utilizing novel Mid-IR Si-based photonic integrated circuits (PICs) filter and wide-band Mid-IR Super Luminescent Light Emitting Diodes (SLEDs), we show the concept of a light source that covers 2.5…3.5 μm wavelength range with a resolution of <1nm. The spectral bands are switchable and tunable and they can be modulated. The source allows for the fabrication of an affordable multi-band gas sensor with good selectivity and sensitivity. The unit price can be lowered in high volumes by utilizing tailored molded IR lens technology and automated packaging and assembling technologies. The status of the development of the key components of the light source are reported. The PIC is based on the use of micron-scale SOI technology, SLED is based on AlGaInAsSb materials and the lenses are tailored heavy metal oxide glasses fabricated by the use of hot-embossing. The packaging concept utilizing automated assembly tools is depicted. In safety and security applications, the Mid-IR wavelength range covered by the novel light source allows for detecting several harmful gas components with a single sensor. At the moment, affordable sources are not available. The market impact is expected to be disruptive, since the devices currently in the market are either complicated, expensive and heavy instruments, or the applied measurement principles are inadequate in terms of stability and selectivity.

Does recruitment source moderate treatment effectiveness? A subgroup analysis from the EVIDENT study, a randomised controlled trial of an internet intervention for depressive symptoms

PubMed Central

Gamon, Carla; Späth, Christina; Berger, Thomas; Meyer, Björn; Hohagen, Fritz; Hautzinger, Martin; Lutz, Wolfgang; Vettorazzi, Eik; Moritz, Steffen; Schröder, Johanna

2017-01-01

Objective This study aims to examine whether the effects of internet interventions for depression generalise to participants recruited in clinical settings. Design This study uses subgroup analysis of the results of a randomised, controlled, single-blind trial. Setting The study takes place in five diagnostic centres in Germany. Participants A total of 1013 people with mild to moderate depressive symptoms were recruited from clinical sources as well as internet forums, statutory insurance companies and other sources. Interventions This study uses either care-as-usual alone (control) or a 12-week internet intervention (Deprexis) plus usual care (intervention). Main outcome measures The primary outcome measure was self-rated depression severity (Patient Health Questionnaire-9) at 3 months and 6 months. Further measures ranged from demographic and clinical parameters to a measure of attitudes towards internet interventions (Attitudes towards Psychological Online Interventions Questionnaire). Results The recruitment source was only associated with very few of the examined demographic and clinical characteristics. Compared with participants recruited from clinical sources, participants recruited through insurance companies were more likely to be employed. Clinically recruited participants were as severely affected as those from other recruitment sources but more sceptical of internet interventions. The effectiveness of the intervention was not differentially associated with recruitment source (treatment by recruitment source interaction=0.28, p=0.84). Conclusion Our results support the hypothesis that the intervention we studied is effective across different recruitment sources including clinical settings. Trial registration number ClinicalTrials.gov NCT01636752. PMID:28710212

Evaluation of Acoustic Doppler Current Profiler measurements of river discharge

USGS Publications Warehouse

Morlock, S.E.

1996-01-01

The standard deviations of the ADCP measurements ranged from approximately 1 to 6 percent and were generally higher than the measurement errors predicted by error-propagation analysis of ADCP instrument performance. These error-prediction methods assume that the largest component of ADCP discharge measurement error is instrument related. The larger standard deviations indicate that substantial portions of measurement error may be attributable to sources unrelated to ADCP electronics or signal processing and are functions of the field environment.

3FHL: The Third Catalog of Hard Fermi -LAT Sources

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

Ajello, M.; Atwood, W. B.; Baldini, L.

Here, we present a catalog of sources detected above 10 GeV by the Fermi Large Area Telescope (LAT) in the first 7 years of data using the Pass 8 event-level analysis. This is the Third Catalog of Hard Fermi-LAT Sources (3FHL), containing 1556 objects characterized in the 10 GeV–2 TeV energy range. The sensitivity and angular resolution are improved by factors of 3 and 2 relative to the previous LAT catalog at the same energies (1FHL). The vast majority of detected sources (79%) are associated with extragalactic counterparts at other wavelengths, including 16 sources located at very high redshift (zmore » > 2). Of the sources, 8% have Galactic counterparts and 13% are unassociated (or associated with a source of unknown nature). The high-latitude sky and the Galactic plane are observed with a flux sensitivity of 4.4 to 9.5 × 10 -11 ph cm -2 s -1, respectively (this is approximately 0.5% and 1% of the Crab Nebula flux above 10 GeV). The catalog includes 214 new γ-ray sources. The substantial increase in the number of photons (more than 4 times relative to 1FHL and 10 times to 2FHL) also allows us to measure significant spectral curvature for 32 sources and find flux variability for 163 of them. We also estimate that for the same flux limit of 10 -12 erg cm -2 s -1, the energy range above 10 GeV has twice as many sources as the range above 50 GeV, highlighting the importance, for future Cherenkov telescopes, of lowering the energy threshold as much as possible.« less

3FHL: The Third Catalog of Hard Fermi -LAT Sources

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

Ajello, M.; Atwood, W. B.; Baldini, L.

We present a catalog of sources detected above 10 GeV by the Fermi Large Area Telescope (LAT) in the first 7 years of data using the Pass 8 event-level analysis. This is the Third Catalog of Hard Fermi -LAT Sources (3FHL), containing 1556 objects characterized in the 10 GeV–2 TeV energy range. The sensitivity and angular resolution are improved by factors of 3 and 2 relative to the previous LAT catalog at the same energies (1FHL). The vast majority of detected sources (79%) are associated with extragalactic counterparts at other wavelengths, including 16 sources located at very high redshift (more » z > 2). Of the sources, 8% have Galactic counterparts and 13% are unassociated (or associated with a source of unknown nature). The high-latitude sky and the Galactic plane are observed with a flux sensitivity of 4.4 to 9.5 × 10{sup −11} ph cm{sup −2} s{sup −1}, respectively (this is approximately 0.5% and 1% of the Crab Nebula flux above 10 GeV). The catalog includes 214 new γ -ray sources. The substantial increase in the number of photons (more than 4 times relative to 1FHL and 10 times to 2FHL) also allows us to measure significant spectral curvature for 32 sources and find flux variability for 163 of them. Furthermore, we estimate that for the same flux limit of 10{sup −12} erg cm{sup −2} s{sup −1}, the energy range above 10 GeV has twice as many sources as the range above 50 GeV, highlighting the importance, for future Cherenkov telescopes, of lowering the energy threshold as much as possible.« less

3FHL: The Third Catalog of Hard Fermi-LAT Sources

NASA Astrophysics Data System (ADS)

Ajello, M.; Atwood, W. B.; Baldini, L.; Ballet, J.; Barbiellini, G.; Bastieri, D.; Bellazzini, R.; Bissaldi, E.; Blandford, R. D.; Bloom, E. D.; Bonino, R.; Bregeon, J.; Britto, R. J.; Bruel, P.; Buehler, R.; Buson, S.; Cameron, R. A.; Caputo, R.; Caragiulo, M.; Caraveo, P. A.; Cavazzuti, E.; Cecchi, C.; Charles, E.; Chekhtman, A.; Cheung, C. C.; Chiaro, G.; Ciprini, S.; Cohen, J. M.; Costantin, D.; Costanza, F.; Cuoco, A.; Cutini, S.; D'Ammando, F.; de Palma, F.; Desiante, R.; Digel, S. W.; Di Lalla, N.; Di Mauro, M.; Di Venere, L.; Domínguez, A.; Drell, P. S.; Dumora, D.; Favuzzi, C.; Fegan, S. J.; Ferrara, E. C.; Fortin, P.; Franckowiak, A.; Fukazawa, Y.; Funk, S.; Fusco, P.; Gargano, F.; Gasparrini, D.; Giglietto, N.; Giommi, P.; Giordano, F.; Giroletti, M.; Glanzman, T.; Green, D.; Grenier, I. A.; Grondin, M.-H.; Grove, J. E.; Guillemot, L.; Guiriec, S.; Harding, A. K.; Hays, E.; Hewitt, J. W.; Horan, D.; Jóhannesson, G.; Kensei, S.; Kuss, M.; La Mura, G.; Larsson, S.; Latronico, L.; Lemoine-Goumard, M.; Li, J.; Longo, F.; Loparco, F.; Lott, B.; Lubrano, P.; Magill, J. D.; Maldera, S.; Manfreda, A.; Mazziotta, M. N.; McEnery, J. E.; Meyer, M.; Michelson, P. F.; Mirabal, N.; Mitthumsiri, W.; Mizuno, T.; Moiseev, A. A.; Monzani, M. E.; Morselli, A.; Moskalenko, I. V.; Negro, M.; Nuss, E.; Ohsugi, T.; Omodei, N.; Orienti, M.; Orlando, E.; Palatiello, M.; Paliya, V. S.; Paneque, D.; Perkins, J. S.; Persic, M.; Pesce-Rollins, M.; Piron, F.; Porter, T. A.; Principe, G.; Rainò, S.; Rando, R.; Razzano, M.; Razzaque, S.; Reimer, A.; Reimer, O.; Reposeur, T.; Saz Parkinson, P. M.; Sgrò, C.; Simone, D.; Siskind, E. J.; Spada, F.; Spandre, G.; Spinelli, P.; Stawarz, L.; Suson, D. J.; Takahashi, M.; Tak, D.; Thayer, J. G.; Thayer, J. B.; Thompson, D. J.; Torres, D. F.; Torresi, E.; Troja, E.; Vianello, G.; Wood, K.; Wood, M.

2017-10-01

We present a catalog of sources detected above 10 GeV by the Fermi Large Area Telescope (LAT) in the first 7 years of data using the Pass 8 event-level analysis. This is the Third Catalog of Hard Fermi-LAT Sources (3FHL), containing 1556 objects characterized in the 10 GeV-2 TeV energy range. The sensitivity and angular resolution are improved by factors of 3 and 2 relative to the previous LAT catalog at the same energies (1FHL). The vast majority of detected sources (79%) are associated with extragalactic counterparts at other wavelengths, including 16 sources located at very high redshift (z > 2). Of the sources, 8% have Galactic counterparts and 13% are unassociated (or associated with a source of unknown nature). The high-latitude sky and the Galactic plane are observed with a flux sensitivity of 4.4 to 9.5 × 10-11 ph cm-2 s-1, respectively (this is approximately 0.5% and 1% of the Crab Nebula flux above 10 GeV). The catalog includes 214 new γ-ray sources. The substantial increase in the number of photons (more than 4 times relative to 1FHL and 10 times to 2FHL) also allows us to measure significant spectral curvature for 32 sources and find flux variability for 163 of them. Furthermore, we estimate that for the same flux limit of 10-12 erg cm-2 s-1, the energy range above 10 GeV has twice as many sources as the range above 50 GeV, highlighting the importance, for future Cherenkov telescopes, of lowering the energy threshold as much as possible.

3FHL: The Third Catalog of Hard Fermi -LAT Sources

DOE PAGES

Ajello, M.; Atwood, W. B.; Baldini, L.; ...

2017-09-27

Here, we present a catalog of sources detected above 10 GeV by the Fermi Large Area Telescope (LAT) in the first 7 years of data using the Pass 8 event-level analysis. This is the Third Catalog of Hard Fermi-LAT Sources (3FHL), containing 1556 objects characterized in the 10 GeV–2 TeV energy range. The sensitivity and angular resolution are improved by factors of 3 and 2 relative to the previous LAT catalog at the same energies (1FHL). The vast majority of detected sources (79%) are associated with extragalactic counterparts at other wavelengths, including 16 sources located at very high redshift (zmore » > 2). Of the sources, 8% have Galactic counterparts and 13% are unassociated (or associated with a source of unknown nature). The high-latitude sky and the Galactic plane are observed with a flux sensitivity of 4.4 to 9.5 × 10 -11 ph cm -2 s -1, respectively (this is approximately 0.5% and 1% of the Crab Nebula flux above 10 GeV). The catalog includes 214 new γ-ray sources. The substantial increase in the number of photons (more than 4 times relative to 1FHL and 10 times to 2FHL) also allows us to measure significant spectral curvature for 32 sources and find flux variability for 163 of them. We also estimate that for the same flux limit of 10 -12 erg cm -2 s -1, the energy range above 10 GeV has twice as many sources as the range above 50 GeV, highlighting the importance, for future Cherenkov telescopes, of lowering the energy threshold as much as possible.« less

Open-Source Automated Mapping Four-Point Probe.

PubMed

Chandra, Handy; Allen, Spencer W; Oberloier, Shane W; Bihari, Nupur; Gwamuri, Jephias; Pearce, Joshua M

2017-01-26

Scientists have begun using self-replicating rapid prototyper (RepRap) 3-D printers to manufacture open source digital designs of scientific equipment. This approach is refined here to develop a novel instrument capable of performing automated large-area four-point probe measurements. The designs for conversion of a RepRap 3-D printer to a 2-D open source four-point probe (OS4PP) measurement device are detailed for the mechanical and electrical systems. Free and open source software and firmware are developed to operate the tool. The OS4PP was validated against a wide range of discrete resistors and indium tin oxide (ITO) samples of different thicknesses both pre- and post-annealing. The OS4PP was then compared to two commercial proprietary systems. Results of resistors from 10 to 1 MΩ show errors of less than 1% for the OS4PP. The 3-D mapping of sheet resistance of ITO samples successfully demonstrated the automated capability to measure non-uniformities in large-area samples. The results indicate that all measured values are within the same order of magnitude when compared to two proprietary measurement systems. In conclusion, the OS4PP system, which costs less than 70% of manual proprietary systems, is comparable electrically while offering automated 100 micron positional accuracy for measuring sheet resistance over larger areas.

Effects of improper source coupling in frequency-domain near-infrared spectroscopy

NASA Astrophysics Data System (ADS)

Noponen, T. E. J.; Kotilahti, K.; Nissilä, I.; Kajava, T.; Meriläinen, P. T.

2010-05-01

Currently, there is no widely used method to assess the reliability of contact between optodes and tissue in near-infrared spectroscopy (NIRS). In this study we observe a high linear dependence (R2 ~ 0.99) of the logarithmic modulation amplitude (ln(IAC)), average intensity (ln(IDC)) and phase (phi) on the source-detector distance (SDD) ranging from ~20 to 50 mm on human forehead measurements. The regression of phi is clearly reduced in measurements where light leakage occurs, mainly due to insufficient contact between the source optode and tissue. Utilizing this observation, a novel criterion to detect light leakage is developed. The criterion is applied to study the reliability of hemodynamic responses measured on the human forehead when breathing carbon dioxide-enriched air and during hyperventilation. The contrast of the signals is significantly lower in measurements which were adversely affected by light leakage. Furthermore, such unreliable signals at SDDs >= 50 mm correlate significantly (for \\rm [HbO_2] p < 0.01 and for [HbR] p < 0.001) better with the signals measured at SDDs < 20 mm. Using this method, poor contact between the source optode and tissue can be detected and corrected before the actual measurement, which enables us to avoid the acquisition of low contrast cortical signals.

Measurements of methane emissions from natural gas gathering facilities and processing plants: measurement methods

DOE PAGES

Roscioli, J. R.; Yacovitch, T. I.; Floerchinger, C.; ...

2015-05-07

Increased natural gas production in recent years has spurred intense interest in methane (CH 4) emissions associated with its production, gathering, processing, transmission, and distribution. Gathering and processing facilities (G&P facilities) are unique in that the wide range of gas sources (shale, coal-bed, tight gas, conventional, etc.) results in a wide range of gas compositions, which in turn requires an array of technologies to prepare the gas for pipeline transmission and distribution. We present an overview and detailed description of the measurement method and analysis approach used during a 20-week field campaign studying CH 4 emissions from the natural gasmore » G&P facilities between October 2013 and April 2014. Dual-tracer flux measurements and on-site observations were used to address the magnitude and origins of CH 4 emissions from these facilities. The use of a second tracer as an internal standard revealed plume-specific uncertainties in the measured emission rates of 20–47%, depending upon plume classification. Furthermore, combining downwind methane, ethane (C 2H 6), carbon monoxide (CO), carbon dioxide (CO 2), and tracer gas measurements with on-site tracer gas release allows for quantification of facility emissions and in some cases a more detailed picture of source locations.« less

High Precision Ranging and Range-Rate Measurements over Free-Space-Laser Communication Link

NASA Technical Reports Server (NTRS)

Yang, Guangning; Lu, Wei; Krainak, Michael; Sun, Xiaoli

2016-01-01

We present a high-precision ranging and range-rate measurement system via an optical-ranging or combined ranging-communication link. A complete bench-top optical communication system was built. It included a ground terminal and a space terminal. Ranging and range rate tests were conducted in two configurations. In the communication configuration with 622 data rate, we achieved a two-way range-rate error of 2 microns/s, or a modified Allan deviation of 9 x 10 (exp -15) with 10 second averaging time. Ranging and range-rate as a function of Bit Error Rate of the communication link is reported. They are not sensitive to the link error rate. In the single-frequency amplitude modulation mode, we report a two-way range rate error of 0.8 microns/s, or a modified Allan deviation of 2.6 x 10 (exp -15) with 10 second averaging time. We identified the major noise sources in the current system as the transmitter modulation injected noise and receiver electronics generated noise. A new improved system will be constructed to further improve the system performance for both operating modes.

Measuring cosmological parameters

PubMed Central

Freedman, Wendy L.

1998-01-01

In this review, the status of measurements of the matter density (Ωm), the vacuum energy density or cosmological constant (ΩΛ), the Hubble constant (H0), and the ages of the oldest measured objects (t0) are summarized. Three independent types of methods for measuring the Hubble constant are considered: the measurement of time delays in multiply imaged quasars, the Sunyaev–Zel’dovich effect in clusters, and Cepheid-based extragalactic distances. Many recent independent dynamical measurements are yielding a low value for the matter density (Ωm ≈ 0.2–0.3). A wide range of Hubble constant measurements appear to be converging in the range of 60–80 km/sec per megaparsec. Areas where future improvements are likely to be made soon are highlighted—in particular, measurements of anisotropies in the cosmic microwave background. Particular attention is paid to sources of systematic error and the assumptions that underlie many of the measurement methods. PMID:9419315

SU-E-J-125: Classification of CBCT Noises in Terms of Their Contribution to Proton Range Uncertainty

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

Brousmiche, S; Orban de Xivry, J; Macq, B

2014-06-01

Purpose: This study assesses the potential use of CBCT images in adaptive protontherapy by estimating the contribution of the main sources of noise and calibration errors to the proton range uncertainty. Methods: Measurements intended to highlight each particular source have been achieved by adapting either the testbench configuration, e.g. use of filtration, fan-beam collimation, beam stop arrays, phantoms and detector reset light, or the sequence of correction algorithms including water precorrection. Additional Monte-Carlo simulations have been performed to complement these measurements, especially for the beam hardening and the scatter cases. Simulations of proton beams penetration through the resulting images havemore » then been carried out to quantify the range change due to these effects. The particular case of a brain irradiation is considered mainly because of the multiple effects that the skull bones have on the internal soft tissues. Results: On top of the range error sources is the undercorrection of scatter. Its influence has been analyzed from a comparison of fan-beam and full axial FOV acquisitions. In this case, large range errors of about 12 mm can be reached if the assumption is made that the scatter has only a constant contribution over the projection images. Even the detector lag, which a priori induces a much smaller effect, has been shown to contribute for up to 2 mm to the overall error if its correction only aims at reducing the skin artefact. This last result can partially be understood by the larger interface between tissues and bones inside the skull. Conclusion: This study has set the basis of a more systematical analysis of the effect CBCT noise on range uncertainties based on a combination of measurements, simulations and theoretical results. With our method, even more subtle effects such as the cone-beam artifact or the detector lag can be assessed. SBR and JOR are financed by iMagX, a public-private partnership between the region Wallone of Belgium and IBA under convention #1217662.« less

Nevada STORMS project: Measurement of mercury emissions from naturally enriched surfaces

USGS Publications Warehouse

Gustin, M.S.; Lindberg, S.; Marsik, F.; Casimir, A.; Ebinghaus, R.; Edwards, G.; Hubble-Fitzgerald, C.; Kemp, R.; Kock, H.; Leonard, T.; London, J.; Majewski, M.; Montecinos, C.; Owens, J.; Pilote, M.; Poissant, L.; Rasmussen, P.; Schaedlich, F.; Schneeberger, D.; Schroeder, W.; Sommar, J.; Turner, R.; Vette, A.; Wallschlaeger, D.; Xiao, Z.; Zhang, H.

1999-01-01

Diffuse anthropogenic and naturally mercury-enriched areas represent long-lived sources of elemental mercury to the atmosphere. The Nevada Study and Tests of the Release of Mercury From Soils (STORMS) project focused on the measurement of mercury emissions from a naturally enriched area. During the project, concurrent measurements of mercury fluxes from naturally mercury-enriched substrate were made September 1-4, 1997, using four micrometeorological methods and seven field flux chambers. Ambient air mercury concentrations ranged from 2 to nearly 200 ng m-3 indicating that the field site is a source of atmospheric mercury. The mean daytime mercury fluxes, during conditions of no precipitation, measured with field chambers were 50 to 360 ng m-2 h-1, and with the micrometeorological methods were 230 to 600 ng m-2 h-1. This wide range in mercury emission rates reflects differences in method experimental designs and local source strengths. Mercury fluxes measured by many field chambers were significantly different (p < 0.05) but linearly correlated. This indicates that field chambers responded similarly to environmental conditions, but differences in experimental design and site heterogeneity had a significant influence on the magnitude of mercury fluxes. Data developed during the field study demonstrated that field flux chambers are ideal for assessment of the physicochemical processes driving mercury flux and development of an understanding of the magnitude of the influence of individual factors on flux. In general, mean mercury fluxes measured with micrometeorological methods during daytime periods were nearly 3 times higher than mean fluxes measured with field flux chambers. Micrometeorological methods allow for derivation of a representative mercury flux occurring from an unconstrained system and provide an assessment of the actual magnitude and variability of fluxes occurring from an area. Copyright 1999 by the American Geophysical Union.

Visible and near-ultraviolet spectra of low-pressure rare-gas microwave discharges

NASA Technical Reports Server (NTRS)

Campbell, J. P.; Spisz, E. W.; Bowman, R. L.

1971-01-01

The spectral emission characteristics of three commercial low pressure rare gas discharge lamps wire obtained in the near ultraviolet and visible wavelength range. All three lamps show a definite continuum over the entire wavelength range from 0.185 to 0.6 micrometers. Considerable line emission is superimposed on much of the continuum for wavelengths greater than 0.35 micrometers. These sources were used to make transmittance measurements on quartz samples in the near ultraviolet wavelength range.

Bright x-ray stainless steel K-shell source development at the National Ignition Facility

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

May, M. J.; Fournier, K. B.; Colvin, J. D.

2015-06-15

High x-ray conversion efficiency (XRCE) K-shell sources are being developed for high energy density experiments for use as backlighters and for the testing of materials exposed to high x-ray fluxes and fluences. Recently, sources with high XRCE in the K-shell x-ray energy range of iron and nickel were investigated at the National Ignition Facility (NIF). The x-ray conversion efficiency in the 5–9 keV spectral range was determined to be 6.8% ± 0.3%. These targets were 4.1 mm diameter, 4 mm tall hollow epoxy tubes having a 50 μm thick wall supporting a tube of 3 to 3.5 μm thick stainless steel. The NIF laser deposited ∼460 kJ ofmore » 3ω light into the target in a 140 TW, 3.3 ns square pulse. The absolute x-ray emission of the source was measured by two calibrated Dante x-ray spectrometers. Time resolved images filtered for the Fe K-shell were recorded to follow the heating of the target. Time integrated high-resolution spectra were recorded in the K-shell range.« less

Bright x-ray stainless steel K-shell source development at the National Ignition Facility

DOE PAGES

May, M. J.; Fournier, K. B.; Colvin, J. D.; ...

2015-06-01

High x-ray conversion efficiency (XRCE) K-shell sources are being developed for high energy density experiments for use as backlighters and for the testing of materials exposed to high x-ray fluxes and fluences. Recently, sources with high XRCE in the K-shell x-ray energy range of iron and nickel were investigated at the National Ignition Facility (NIF). The x-ray conversion efficiency in the 5–9 keV spectral range was determined to be 6.8% ± 0.3%. These targets were 4.1 mm diameter, 4 mm tall hollow epoxy tubes having a 50 μm thick wall supporting a tube of 3 to 3.5 μm thick stainlessmore » steel. The NIF laser deposited ~460 kJ of 3ω light into the target in a 140 TW, 3.3 ns square pulse. The absolute x-ray emission of the source was measured by two calibrated Dante x-ray spectrometers. In conclusion, time resolved images filtered for the Fe K-shell were recorded to follow the heating of the target. Time integrated high-resolution spectra were recorded in the K-shell range« less

Energy Spectra of Abundant Cosmic-ray Nuclei in Sources, According to the ATIC Experiment

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

Panov, A. D.; Sokolskaya, N. V.; Zatsepin, V. I., E-mail: panov@dec1.sinp.msu.ru

One of the main results of the ATIC (Advanced Thin Ionization Calorimeter) experiment is a collection of energy spectra of abundant cosmic-ray nuclei: protons, He, C, O, Ne, Mg, Si, and Fe measured in terms of energy per particle in the energy range from 50 GeV to tens of teraelectronvolts. In this paper, the ATIC energy spectra of abundant primary nuclei are back-propagated to the spectra in sources in terms of magnetic rigidity using a leaky-box approximation of three different GALPROP-based diffusion models of propagation that fit the latest B/C data of the AMS-02 experiment. It is shown that themore » results of a comparison of the slopes of the spectra in sources are weakly model dependent; therefore the differences of spectral indices are reliable data. A regular growth of the steepness of spectra in sources in the range of magnetic rigidity of 50–1350 GV is found for a charge range from helium to iron. This conclusion is statistically reliable with significance better than 3.2 standard deviations. The results are discussed and compared to the data of other modern experiments.« less

Bright x-ray stainless steel K-shell source development at the National Ignition Facility

NASA Astrophysics Data System (ADS)

May, M. J.; Fournier, K. B.; Colvin, J. D.; Barrios, M. A.; Dewald, E. L.; Hohenberger, M.; Moody, J.; Patterson, J. R.; Schneider, M.; Widmann, K.; Regan, S. P.

2015-06-01

High x-ray conversion efficiency (XRCE) K-shell sources are being developed for high energy density experiments for use as backlighters and for the testing of materials exposed to high x-ray fluxes and fluences. Recently, sources with high XRCE in the K-shell x-ray energy range of iron and nickel were investigated at the National Ignition Facility (NIF). The x-ray conversion efficiency in the 5-9 keV spectral range was determined to be 6.8% ± 0.3%. These targets were 4.1 mm diameter, 4 mm tall hollow epoxy tubes having a 50 μm thick wall supporting a tube of 3 to 3.5 μm thick stainless steel. The NIF laser deposited ˜460 kJ of 3ω light into the target in a 140 TW, 3.3 ns square pulse. The absolute x-ray emission of the source was measured by two calibrated Dante x-ray spectrometers. Time resolved images filtered for the Fe K-shell were recorded to follow the heating of the target. Time integrated high-resolution spectra were recorded in the K-shell range.

Variations of thiaminase I activity pH dependencies among typical Great Lakes forage fish and Paenibacillus thiaminolyticus.

USGS Publications Warehouse

Zajicek, J.L.; Brown, L.; Brown, S.B.; Honeyfield, D.C.; Fitzsimons, J.D.; Tillitt, D.E.

2009-01-01

The source of thiaminase in the Great Lakes food web remains unknown. Biochemical characterization of the thiaminase I activities observed in forage fish was undertaken to provide insights into potential thiaminase sources and to optimize catalytic assay conditions. We measured the thiaminase I activities of crude extracts from five forage fish species and one strain of Paenibacillus thiaminolyticus over a range of pH values. The clupeids, alewife Alosa pseudoharengus and gizzard shad Dorosoma cepedianum, had very similar thiaminase I pH dependencies, with optimal activity ranges (> or = 90% of maximum activity) between pH 4.6 and 5.5. Rainbow smelt Osmerus mordax and spottail shiner Notropis hudsonius had optimal activity ranges between pH 5.5-6.6. The thiaminase I activity pH dependence profile of P. thiaminolyticus had an optimal activity range between pH 5.4 and 6.3, which was similar to the optimal range for rainbow smelt and spottail shiners. Incubation of P. thiaminolyticus extracts with extracts from bloater Coregonus hoyi (normally, bloaters have little or no detectable thiaminase I activity) did not significantly alter the pH dependence profile of P. thiaminolyticus-derived thiaminase I, such that it continued to resemble that of the rainbow smelt and spottail shiner, with an apparent optimal activity range between pH 5.7 and 6.6. These data are consistent with the hypothesis of a bacterial source for thiaminase I in the nonclupeid species of forage fish; however, the data also suggest different sources of thiaminase I enzymes in the clupeid species.

MEASURING THE ACUTE TOXICITY OF ESTUARINE SEDIMENTS

EPA Science Inventory

Estuarine sediments frequently are repositories and sources of anthropogenic contaminants. Toxicity is one method of assessing the environmental quality of sediments, yet because of the extreme range of salinities that characterize estuaries few infaunal organisms have both the p...

Source apportionment of fine particulate matter measured in an industrialized coastal urban area of South Texas

NASA Astrophysics Data System (ADS)

Karnae, Saritha; John, Kuruvilla

2011-07-01

Corpus Christi is a growing industrialized urban airshed in South Texas impacted by local emissions and regional transport of fine particulate matter (PM 2.5). Positive matrix factorization (PMF2) technique was used to evaluate particulate matter pollution in the urban airshed by estimating the types of sources and its corresponding mass contributions affecting the measured ambient PM 2.5 levels. Fine particulate matter concentrations by species measured during July 2003 through December 2008 at a PM 2.5 speciation site were used in this study. PMF2 identified eight source categories, of which secondary sulfates were the dominant source category accounting for 30.4% of the apportioned mass. The other sources identified included aged sea salt (18.5%), biomass burns (12.7%), crustal dust (10.1%), traffic (9.7%), fresh sea salt (8.1%), industrial sources (6%), and a co-mingled source of oil combustion & diesel emissions (4.6%). The apportioned PM mass showed distinct seasonal variability between source categories. The PM levels in Corpus Christi were affected by biomass burns in Mexico and Central America during April and May, sub-Saharan dust storms from Africa during the summer months, and a continental haze episode during August and September with significant transport from the highly industrialized areas of Texas and the neighboring states. Potential source contribution function (PSCF) analysis was performed and it identified source regions and the influence of long-range transport of fine particulate matter affecting this urban area.

High-Resolution Fast-Neutron Spectrometry for Arms Control and Treaty Verification

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

David L. Chichester; James T. Johnson; Edward H. Seabury

2012-07-01

Many nondestructive nuclear analysis techniques have been developed to support the measurement needs of arms control and treaty verification, including gross photon and neutron counting, low- and high-resolution gamma spectrometry, time-correlated neutron measurements, and photon and neutron imaging. One notable measurement technique that has not been extensively studied to date for these applications is high-resolution fast-neutron spectrometry (HRFNS). Applied for arms control and treaty verification, HRFNS has the potential to serve as a complimentary measurement approach to these other techniques by providing a means to either qualitatively or quantitatively determine the composition and thickness of non-nuclear materials surrounding neutron-emitting materials.more » The technique uses the normally-occurring neutrons present in arms control and treaty verification objects of interest as an internal source of neutrons for performing active-interrogation transmission measurements. Most low-Z nuclei of interest for arms control and treaty verification, including 9Be, 12C, 14N, and 16O, possess fast-neutron resonance features in their absorption cross sections in the 0.5- to 5-MeV energy range. Measuring the selective removal of source neutrons over this energy range, assuming for example a fission-spectrum starting distribution, may be used to estimate the stoichiometric composition of intervening materials between the neutron source and detector. At a simpler level, determination of the emitted fast-neutron spectrum may be used for fingerprinting 'known' assemblies for later use in template-matching tests. As with photon spectrometry, automated analysis of fast-neutron spectra may be performed to support decision making and reporting systems protected behind information barriers. This paper will report recent work at Idaho National Laboratory to explore the feasibility of using HRFNS for arms control and treaty verification applications, including simulations and experiments, using fission-spectrum neutron sources to assess neutron transmission through composite low-Z attenuators.« less

The impact of networks of robotic telescopes in continuous monitoring of high energy cosmic sources

NASA Astrophysics Data System (ADS)

Giovannelli, Franco; Sabau-Graziati, Lola

High energy (HE) cosmic sources are characterized by emissions in a wide range of the electromagnetic spectrum. In order to clarify their behavior and understand the involved physics it is necessary to perform simultaneous measurements in a range of energy as wide as possible. This makes it necessary to use different techniques and instrumentation both space- and ground-based. Simultaneous observations are in general very difficult to be performed because they need the involvement of many instruments that belong to many experiments under the control of many groups and countries. However, since the importance of multifrequency measurements is now universally recognized, many efforts are made in order to obtain such measurements. Our group has been a pioneer in such a kind of measurements since middle of 1970s. We will briefly discuss the impact of such measurements in different class of HE cosmic sources, such as T Tauri stars (TTSs), active galactic nuclei (AGNs), gamma-ray bursts (GRBs), X-ray binary systems (XRBs), and cataclysmic variables (CVs). This discussion is mainly based on the review paper "The impact of the space experiments on our knowledge of the physics of the universe" tep{GiovannelliSabauGraziati2004} and subsequent revisions. We will also discuss the importance of having a network of robotic telescopes that can provide long term optical monitoring of the classes of HE sources already discussed. Such measurements will provide fundamental data for understanding many problems that are still open, such as the physics of the outbursts in flaring systems, the search of rotational periods of white dwarfs in CVs and orbital periods of those systems, rotational periods and periodicities of flare-like events of TTSs, correlations between optical and X-ray flares in X-ray/Be systems, fluctuations in the light curves of AGNs and their correlations with the HE emission in order to test the validity of current models, etc.

Measurement of Gaseous Oxidized Mercury at a SEARCH Network Site in Florida, USA

NASA Astrophysics Data System (ADS)

Huang, J.; Miller, M. B.; Gustin, M. S.

2013-12-01

There are three operationally defined forms of mercury (Hg) that have been measured in the atmosphere. These include gaseous elemental Hg (GEM), gaseous oxidized Hg (GOM), and particle-bound Hg (PBM). The chemical compounds that make up GOM are currently not well understood, and because of this we do not understand its transport and fate. Additionally, there are limitations associated with the current measurement method, the Tekran 2537/1130/1135 system. Recent work has shown that this system underestimates GOM concentrations, and may not measure all forms. Here we describe work building on ongoing research that focuses on understanding the limitations associated with the instrument, and the chemical forms of GOM. Mercury data have been collected at a Southeastern Aerosol Research and Characterization (SEARCH) network site, Outlying Landing Field (OLF), by the University of Nevada-Reno since 2006. This site is located near the Gulf of Mexico in western Florida. This site is potentially influenced by multiple Hg sources including marine air, electricity generating facilities, mobile sources, and long range transport from high elevation and inland regions. Recent work using data from this location and two others in Florida indicated that on top of background deposition, Hg input to OLF is due to local mobile sources, and long range transport in the spring. Air masses with different chemistry have been hypothesized to carry different GOM compounds. To test this hypothesis, an active Hg sampling system that collects GOM on nylon and cation-exchange membranes is being deployed at OLF. Measurements started March 2013. Here we will present data collected so far, and compare concentrations measured to those obtained using a Tekran system. Ancillary data including meteorology, criteria air pollutants, and those collected using surrogated surfaces for dry Hg deposition and Hg passive samplers will be applied to help understand the sources of GOM. Back trajectory analyses will also applied. This new method shows that different forms of GOM are present at OLF.

High-resolution measurement of a bottlenose dolphin's (Tursiops truncatus) biosonar transmission beam pattern in the horizontal plane.

PubMed

Finneran, James J; Branstetter, Brian K; Houser, Dorian S; Moore, Patrick W; Mulsow, Jason; Martin, Cameron; Perisho, Shaun

2014-10-01

Previous measurements of toothed whale echolocation transmission beam patterns have utilized few hydrophones and have therefore been limited to fine angular resolution only near the principal axis or poor resolution over larger azimuthal ranges. In this study, a circular, horizontal planar array of 35 hydrophones was used to measure a dolphin's transmission beam pattern with 5° to 10° resolution at azimuths from -150° to +150°. Beam patterns and directivity indices were calculated from both the peak-peak sound pressure and the energy flux density. The emitted pulse became smaller in amplitude and progressively distorted as it was recorded farther off the principal axis. Beyond ±30° to 40°, the off-axis signal consisted of two distinct pulses whose difference in time of arrival increased with the absolute value of the azimuthal angle. A simple model suggests that the second pulse is best explained as a reflection from internal structures in the dolphin's head, and does not implicate the use of a second sound source. Click energy was also more directional at the higher source levels utilized at longer ranges, where the center frequency was elevated compared to that of the lower amplitude clicks used at shorter range.

First full dynamic range calibration of the JUNGFRAU photon detector

NASA Astrophysics Data System (ADS)

Redford, S.; Andrä, M.; Barten, R.; Bergamaschi, A.; Brückner, M.; Dinapoli, R.; Fröjdh, E.; Greiffenberg, D.; Lopez-Cuenca, C.; Mezza, D.; Mozzanica, A.; Ramilli, M.; Ruat, M.; Ruder, C.; Schmitt, B.; Shi, X.; Thattil, D.; Tinti, G.; Vetter, S.; Zhang, J.

2018-01-01

The JUNGFRAU detector is a charge integrating hybrid silicon pixel detector developed at the Paul Scherrer Institut for photon science applications, in particular for the upcoming free electron laser SwissFEL. With a high dynamic range, analogue readout, low noise and three automatically switching gains, JUNGFRAU promises excellent performance not only at XFELs but also at synchrotrons in areas such as protein crystallography, ptychography, pump-probe and time resolved measurements. To achieve its full potential, the detector must be calibrated on a pixel-by-pixel basis. This contribution presents the current status of the JUNGFRAU calibration project, in which a variety of input charge sources are used to parametrise the energy response of the detector across four orders of magnitude of dynamic range. Building on preliminary studies, the first full calibration procedure of a JUNGFRAU 0.5 Mpixel module is described. The calibration is validated using alternative sources of charge deposition, including laboratory experiments and measurements at ESRF and LCLS. The findings from these measurements are presented. Calibrated modules have already been used in proof-of-principle style protein crystallography experiments at the SLS. A first look at selected results is shown. Aspects such as the conversion of charge to number of photons, treatment of multi-size pixels and the origin of non-linear response are also discussed.

Design and evaluation of an imaging spectrophotometer incorporating a uniform light source.

PubMed

Noble, S D; Brown, R B; Crowe, T G

2012-03-01

Accounting for light that is diffusely scattered from a surface is one of the practical challenges in reflectance measurement. Integrating spheres are commonly used for this purpose in point measurements of reflectance and transmittance. This solution is not directly applicable to a spectral imaging application for which diffuse reflectance measurements are desired. In this paper, an imaging spectrophotometer design is presented that employs a uniform light source to provide diffuse illumination. This creates the inverse measurement geometry to the directional illumination/diffuse reflectance mode typically used for point measurements. The final system had a spectral range between 400 and 1000 nm with a 5.2 nm resolution, a field of view of approximately 0.5 m by 0.5 m, and millimeter spatial resolution. Testing results indicate illumination uniformity typically exceeding 95% and reflectance precision better than 1.7%.

Evaluation of lead levels in children living near a Los Angeles county battery recycling facility.

PubMed Central

Wohl, A R; Dominguez, A; Flessel, P

1996-01-01

This cross-sectional study examined the association between environmental lead measurements surrounding a Los Angeles County battery recycling facility and the blood lead levels of the children living nearby. Environmental lead measurements and blood lead levels of young children living in a community adjacent to a stationary lead source were compared to those living in a community without a stationary lead source. Predictors of blood lead level were identified. The blood lead levels of the children living near the secondary lead smelter were within the normal range (< 5 micrograms/dl). The absence of ground cover was associated with slightly increased blood lead levels; however, this increase was not of biological significance. Lead levels in surface soil near the stationary lead source were elevated compared to the control community; however, the soil affected community, which may be due in part to controls recently installed at the stationary lead source. PMID:8919770

Photoionization Efficiencies of Five Polycyclic Aromatic Hydrocarbons

DOE PAGES

Johansson, K. Olof; Campbell, Matthew F.; Elvati, Paolo; ...

2017-05-18

We have measured photoionization-efficiency curves for pyrene, fluoranthene, chrysene, perylene, and coronene in the photon energy range of 7.5-10.2 eV and derived their photoionization cross-section curves in this energy range. All measurements were performed using tunable vacuum ultraviolet (VUV) radiation generated at the Advanced Light Source synchrotron at Lawrence Berkeley National Laboratory. The VUV radiation was used for photoionization, and detection was performed using a time-of-flight mass spectrometer. We measured the photoionization efficiency of 2,5-dimethylfuran simultaneously with those of pyrene, fluoranthene, chrysene, perylene, and coronene to obtain references of the photon flux during each measurement from the known photoionization cross-sectionmore » curve of 2,5- dimethylfuran.« less

Assimilation of concentration measurements for retrieving multiple point releases in atmosphere: A least-squares approach to inverse modelling

NASA Astrophysics Data System (ADS)

Singh, Sarvesh Kumar; Rani, Raj

2015-10-01

The study addresses the identification of multiple point sources, emitting the same tracer, from their limited set of merged concentration measurements. The identification, here, refers to the estimation of locations and strengths of a known number of simultaneous point releases. The source-receptor relationship is described in the framework of adjoint modelling by using an analytical Gaussian dispersion model. A least-squares minimization framework, free from an initialization of the release parameters (locations and strengths), is presented to estimate the release parameters. This utilizes the distributed source information observable from the given monitoring design and number of measurements. The technique leads to an exact retrieval of the true release parameters when measurements are noise free and exactly described by the dispersion model. The inversion algorithm is evaluated using the real data from multiple (two, three and four) releases conducted during Fusion Field Trials in September 2007 at Dugway Proving Ground, Utah. The release locations are retrieved, on average, within 25-45 m of the true sources with the distance from retrieved to true source ranging from 0 to 130 m. The release strengths are also estimated within a factor of three to the true release rates. The average deviations in retrieval of source locations are observed relatively large in two release trials in comparison to three and four release trials.

Contribution of indoor and outdoor nitrogen dioxide to indoor air quality of wayside shops.

PubMed

Shuai, Jianfei; Yang, Wonho; Ahn, Hogi; Kim, Sunshin; Lee, Seokyong; Yoon, Sung-Uk

2013-06-01

Indoor nitrogen dioxide (NO₂) concentration is an important factor for personal exposure despite the wide distribution of its sources. Exposure to NO₂ may produce adverse health effects. The aims of this study were to characterize the indoor air quality of wayside shops using multiple NO₂ measurements, and to estimate the contribution of outdoor NO₂ sources such as vehicle emission to indoor air quality. Daily indoor and outdoor NO₂ concentrations were measured for 21 consecutive days in wayside shops (5 convenience stores, 5 coffee shops, and 5 restaurants). Contributions of outdoor NO₂ sources to indoor air quality were calculated with penetration factors and source strength factors by indoor mass balance model in winter and summer, respectively. Most wayside shops had significant differences in indoor and outdoor NO₂ concentrations both in winter and in summer. Indoor NO₂ concentrations in restaurants were twice more than those in convenience stores and coffee shops in winter. While outdoor NO₂ contributions in indoor convenience stores and coffee shops were dominant, indoor NO₂ contributions were dominant in restaurants. These could be explained that indoor NO₂ sources such as gas range and smoking mainly affect indoor concentrations comparing to outdoor sources such as vehicle emission. The indoor mass balance model by multiple measurements suggests that quantitative contribution of outdoor air on indoor air quality might be estimated without measurements of ventilation, indoor generation and decay rate.

Experimental study of the thermal-acoustic efficiency in a long turbulent diffusion-flame burner

NASA Technical Reports Server (NTRS)

Mahan, J. R.

1983-01-01

An acoustic source/propagation model is used to interpret measured noise spectra from a long turbulent burner. The acoustic model is based on the perturbation solution of the equations describing the unsteady one-dimensional flow of an inviscid ideal gas with a distributed heat source. The model assumes that the measured noise spectra are due uniquely to the unsteady component of combustion heat release. The model was applied to a long cylindrical hydrogen burner operating over a range of power levels between 4.5 kW and 22.3 kW. Acoustic impedances at the inlet to the burner and at the exit of the tube downstream of the burner were measured and are used as boundary conditions for the model. These measured impedances are also presented.

Background radiation measurements at high power research reactors

NASA Astrophysics Data System (ADS)

Ashenfelter, J.; Balantekin, B.; Baldenegro, C. X.; Band, H. R.; Barclay, G.; Bass, C. D.; Berish, D.; Bowden, N. S.; Bryan, C. D.; Cherwinka, J. J.; Chu, R.; Classen, T.; Davee, D.; Dean, D.; Deichert, G.; Dolinski, M. J.; Dolph, J.; Dwyer, D. A.; Fan, S.; Gaison, J. K.; Galindo-Uribarri, A.; Gilje, K.; Glenn, A.; Green, M.; Han, K.; Hans, S.; Heeger, K. M.; Heffron, B.; Jaffe, D. E.; Kettell, S.; Langford, T. J.; Littlejohn, B. R.; Martinez, D.; McKeown, R. D.; Morrell, S.; Mueller, P. E.; Mumm, H. P.; Napolitano, J.; Norcini, D.; Pushin, D.; Romero, E.; Rosero, R.; Saldana, L.; Seilhan, B. S.; Sharma, R.; Stemen, N. T.; Surukuchi, P. T.; Thompson, S. J.; Varner, R. L.; Wang, W.; Watson, S. M.; White, B.; White, C.; Wilhelmi, J.; Williams, C.; Wise, T.; Yao, H.; Yeh, M.; Yen, Y.-R.; Zhang, C.; Zhang, X.; Prospect Collaboration

2016-01-01

Research reactors host a wide range of activities that make use of the intense neutron fluxes generated at these facilities. Recent interest in performing measurements with relatively low event rates, e.g. reactor antineutrino detection, at these facilities necessitates a detailed understanding of background radiation fields. Both reactor-correlated and naturally occurring background sources are potentially important, even at levels well below those of importance for typical activities. Here we describe a comprehensive series of background assessments at three high-power research reactors, including γ-ray, neutron, and muon measurements. For each facility we describe the characteristics and identify the sources of the background fields encountered. The general understanding gained of background production mechanisms and their relationship to facility features will prove valuable for the planning of any sensitive measurement conducted therein.

Accuracy of iodine quantification using dual energy CT in latest generation dual source and dual layer CT.

PubMed

Pelgrim, Gert Jan; van Hamersvelt, Robbert W; Willemink, Martin J; Schmidt, Bernhard T; Flohr, Thomas; Schilham, Arnold; Milles, Julien; Oudkerk, Matthijs; Leiner, Tim; Vliegenthart, Rozemarijn

2017-09-01

To determine the accuracy of iodine quantification with dual energy computed tomography (DECT) in two high-end CT systems with different spectral imaging techniques. Five tubes with different iodine concentrations (0, 5, 10, 15, 20 mg/ml) were analysed in an anthropomorphic thoracic phantom. Adding two phantom rings simulated increased patient size. For third-generation dual source CT (DSCT), tube voltage combinations of 150Sn and 70, 80, 90, 100 kVp were analysed. For dual layer CT (DLCT), 120 and 140 kVp were used. Scans were repeated three times. Median normalized values and interquartile ranges (IQRs) were calculated for all kVp settings and phantom sizes. Correlation between measured and known iodine concentrations was excellent for both systems (R = 0.999-1.000, p < 0.0001). For DSCT, median measurement errors ranged from -0.5% (IQR -2.0, 2.0%) at 150Sn/70 kVp and -2.3% (IQR -4.0, -0.1%) at 150Sn/80 kVp to -4.0% (IQR -6.0, -2.8%) at 150Sn/90 kVp. For DLCT, median measurement errors ranged from -3.3% (IQR -4.9, -1.5%) at 140 kVp to -4.6% (IQR -6.0, -3.6%) at 120 kVp. Larger phantom sizes increased variability of iodine measurements (p < 0.05). Iodine concentration can be accurately quantified with state-of-the-art DECT systems from two vendors. The lowest absolute errors were found for DSCT using the 150Sn/70 kVp or 150Sn/80 kVp combinations, which was slightly more accurate than 140 kVp in DLCT. • High-end CT scanners allow accurate iodine quantification using different DECT techniques. • Lowest measurement error was found in scans with largest photon energy separation. • Dual-source CT quantified iodine slightly more accurately than dual layer CT.

SU-E-I-79: Source Geometry Dependence of Gamma Well-Counter Measurements

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

Park, M; Belanger, A; Kijewski, M

Purpose: To determine the effect of liquid sample volume and geometry on counting efficiency in a gamma well-counter, and to assess the relative contributions of sample geometry and self-attenuation. Gamma wellcounters are standard equipment in clinical and preclinical studies, for measuring patient blood radioactivity and quantifying animal tissue uptake for tracer development and other purposes. Accurate measurements are crucial. Methods: Count rates were measured for aqueous solutions of 99m- Tc at four liquid volume values in a 1-cm-diam tube and at six volume values in a 2.2-cm-diam vial. Total activity was constant for all volumes, and data were corrected formore » decay. Count rates from a point source in air, supported by a filter paper, were measured at seven heights between 1.3 and 5.7 cm from the bottom of a tube. Results: Sample volume effects were larger for the tube than for the vial. For the tube, count efficiency relative to a 1-cc volume ranged from 1.05 at 0.05 cc to 0.84 at 3 cc. For the vial, relative count efficiency ranged from 1.02 at 0.05 cc to 0.87 at 15 cc. For the point source, count efficiency relative to 1.3 cm from the tube bottom ranged from 0.98 at 1.8 cm to 0.34 at 5.7 cm. The relative efficiency of a 3-cc liquid sample in a tube compared to a 1-cc sample is 0.84; the average relative efficiency for the solid sample in air between heights in the tube corresponding to the surfaces of those volumes (1.3 and 4.8 cm) is 0.81, implying that the major contribution to efficiency loss is geometry, rather than attenuation. Conclusion: Volume-dependent correction factors should be used for accurate quantitation radioactive of liquid samples. Solid samples should be positioned at the bottom of the tube for maximum count efficiency.« less

Impact of Front Range sources on reactive nitrogen concentrations and deposition in Rocky Mountain National Park

PubMed Central

Prenni, Anthony J.; Sullivan, Amy P.; Evanoski-Cole, Ashley R.; Fischer, Emily V.; Callahan, Sara; Sive, Barkley C.; Zhou, Yong; Schichtel, Bret A.; Collett Jr, Jeffrey L.

2018-01-01

Human influenced atmospheric reactive nitrogen (RN) is impacting ecosystems in Rocky Mountain National Park (ROMO). Due to ROMO’s protected status as a Class 1 area, these changes are concerning, and improving our understanding of the contributions of different types of RN and their sources is important for reducing impacts in ROMO. In July–August 2014 the most comprehensive measurements (to date) of RN were made in ROMO during the Front Range Air Pollution and Photochemistry Éxperiment (FRAPPÉ). Measurements included peroxyacetyl nitrate (PAN), C1–C5 alkyl nitrates, and high-time resolution NOx, NOy, and ammonia. A limited set of measurements was extended through October. Co-located measurements of a suite of volatile organic compounds provide information on source types impacting ROMO. Specifically, we use ethane as a tracer of oil and gas operations and tetrachloroethylene (C2Cl4) as an urban tracer to investigate their relationship with RN species and transport patterns. Results of this analysis suggest elevated RN concentrations are associated with emissions from oil and gas operations, which are frequently co-located with agricultural production and livestock feeding areas in the region, and from urban areas. There also are periods where RN at ROMO is impacted by long-range transport. We present an atmospheric RN budget and a nitrogen deposition budget with dry and wet components. Total deposition for the period (7/1–9/30) was estimated at 1.58 kg N/ha, with 87% from wet deposition during this period of above average precipitation. Ammonium wet deposition was the dominant contributor to total nitrogen deposition followed by nitrate wet deposition and total dry deposition. Ammonia was estimated to be the largest contributor to dry deposition followed by nitric acid and PAN (other species included alkyl nitrates, ammonium and nitrate). All three species are challenging to measure routinely, especially at high time resolution.

Sources and composition of PM2.5 in the Colorado Front Range during the DISCOVER-AQ study

NASA Astrophysics Data System (ADS)

Valerino, M. J.; Johnson, J. J.; Izumi, J.; Orozco, D.; Hoff, R. M.; Delgado, R.; Hennigan, C. J.

2017-01-01

Measurements of particulate matter (PM2.5) chemical composition were carried out in Golden, CO, during the Deriving Information on Surface Conditions from Column and Vertically Resolved Observations Relevant to Air Quality (DISCOVER-AQ) field study. Chemical composition was dominated by organic compounds, which comprised an average of 75% of the PM2.5 mass throughout the study. Most of the organic matter was secondary (i.e., secondary organic aerosol) and appears to derive predominantly from regional sources, rather than the Denver metropolitan area. The concentration and composition of PM2.5 in Golden were strongly influenced by highly regular wind patterns and the site's close proximity to the mountains ( 5 km). This second factor may be the cause of distinct differences between observations in Golden and those in downtown Denver, despite a distance between the sites of only 15 km. Concentrations of aerosol nitrate, ammonium, and elemental carbon increased significantly during the daytime when the winds were from the northeast, indicating a strong local source for these compounds. Local sources of dust appeared to minimally impact the Golden site, although this was not likely representative of other conditions in the Colorado Front Range. Conversely, dust that had undergone long-range transport from the southwestern U.S. likely impacted the entire Colorado Front Range, including Golden. During this event, water-soluble Ca2+ concentrations exceeded 1 µg m-3, and the PM2.5/PM10 ratio reached its lowest level throughout the study. The long-range transport of wildfire emissions also impacted the Colorado Front Range for 1-2 days during DISCOVER-AQ. The smoke event was characterized by high concentrations of organics and water-soluble K+. The results show a complex array of sources, and atmospheric processes influence summertime PM in the Colorado Front Range.

Characterizing the oxygen isotopic composition of phosphate sources to aquatic ecosystems

USGS Publications Warehouse

Young, M.B.; McLaughlin, K.; Kendall, C.; Stringfellow, W.; Rollog, M.; Elsbury, K.; Donald, E.; Paytan, A.

2009-01-01

The oxygen isotopic composition of dissolved inorganic phosphate (δ18Op) in many aquatic ecosystems is not in isotopic equilibrium with ambient water and, therefore, may reflect the source δ18Op. Identification of phosphate sources to water bodies is critical for designing best management practices for phosphate load reduction to control eutrophication. In order for δ18O p to be a useful tool for source tracking, the δ18Op of phosphate sources must be distinguishable from one another; however, the δ18Op of potential sources has not been well characterized. We measured the δ18O p of a variety of known phosphate sources, including fertilizers, semiprocessed phosphorite ore, particulate aerosols, detergents, leachates of vegetation, soil, animal feces, and wastewater treatment plant effluent. We found a considerable range of δ18Op values (from +8.4 to +24.9‰) for the various sources, and statistically significant differences were found between several of the source types. δ18Op measured in three different fresh water systems was generally not in equilibrium with ambient water. Although there is overlap in δ18Op values among the groups of samples, our results indicate that some sources are isotopically distinct and δ18Op can be used for identifying phosphate sources to aquatic systems.

Identification and measurement of combustion noise from a turbofan engine using correlation and coherence techniques. Ph.D. Thesis

NASA Technical Reports Server (NTRS)

Karchmer, A. M.

1977-01-01

Fluctuating pressure measurements within the combustor and tailpipe of a turbofan engine are made simultaneously with far field acoustic measurements. The pressure measurements within the engine are accomplished with cooled semi-infinite waveguide probes utilizing conventional condenser microphones as the transducers. The measurements are taken over a broad range of engine operating conditions and for 16 far field microphone positions between 10 deg and 160 deg relative to the engine inlet axis. Correlation and coherence techniques are used to determine the relative phase and amplitude relationships between the internal pressures and far field acoustic pressures. The results indicate that the combustor is a low frequency source region for acoustic propagation through the tailpipe and out to the far field. Specifically, it is found that the relation between source pressure and the resulting sound pressure involves a 180 deg phase shift. The latter result is obtained by Fourier transforming the cross correlation function between the source pressure and acoustic pressure after removing the propagation delay time. Further, it is found that the transfer function between the source pressure and acoustic pressure has a magnitude approximately proportional to frequency squared. These results are shown to be consistent with a model using a modified source term in Lighthill's turbulence stress tensor, wherein the fluctuating Reynolds stresses are replaced with the pressure fluctuations due to fluctuating entropy.

Chemical composition of aerosol measurements in the air pollution plume during KORUS-AQ

NASA Astrophysics Data System (ADS)

Park, T.; Lee, J. B.; Lim, Y. J.; Ahn, J.; Park, J. S.; Soo, C. J.; Kim, J.; Park, S.; Lee, Y.; Desyaterik, Y.; Collett, J. L., Jr.; Lee, T.

2017-12-01

The Korean peninsula is a great place to study different sources of the aerosols: urban, rural and marine. In addition, Seoul is one of the large metropolitan areas in the world and has a variety of sources because half of the Korean population lives in Seoul, which comprises only 12% of the country's area. To understand the chemical composition of aerosol form long-range transport and local sources better, an Aerodyne High Resolution Time of Flight Aerosol Mass Spectrometer (HR-ToF-AMS) was deployed on an airborne platform (NASA DC-8 aircraft). The HR-ToF-AMS is capable of measuring non-refractory size resolved chemical composition of submicron particle(NR-PM1) in the air pollution plume, including mass concentration of organic carbon, nitrate, sulfate, and ammonium with 10 seconds time resolution. The measurements were performed twenty times research flight for understanding characteristic of the air pollution from May to June, 2016 on the South Korean peninsula during KORUS-AQ 2016 campaign. The scientific goal of this study is to characterize aerosol chemical properties and mass concentration in order to understand the role of the long-range transport from northeast Asia to South Korea, and influence of the local sources. To brief, organics dominated during all of flights. Also, organics and nitrate were dominant around energy industrial complex near by Taean, South Korea. The presentation will provide an overview of the composition of NR-PM1 measured in air pollution plumes, and deliver detail information about width, depth and spatial distribution of the pollutant in the air pollution plumes. The results of this study will provide high temporal and spatial resolved details on the air pollution plumes, which are valuable input parameters of aerosol properties for the current air quality models.

Demonstration of a rapidly-swept external cavity quantum cascade laser for atmospheric sensing applications

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

Brumfield, Brian E.; Taubman, Matthew S.; Phillips, Mark C.

2016-07-01

The application of quantum cascade lasers (QCLs) in atmospheric science for trace detection of gases has been demonstrated using sensors in point or remote sensing configurations. Many of these systems utilize single narrowly-tunable (~10 cm-1) distributed feedback (DFB-) QCLs that limit simultaneous detection to a restricted number of small chemical species like H2O or N2O. The narrow wavelength range of DFB-QCLs precludes accurate quantification of large chemical species with broad rotationally-unresolved vibrational spectra, such as volatile organic compounds, that play an important role in the chemistry of the atmosphere. External-cavity (EC-) QCL systems are available that offer tuning ranges >100more » cm-1, making them excellent IR sources for measuring multiple small and large chemical species in the atmosphere. While the broad wavelength coverage afforded by an EC system enables measurements of large chemical species, most commercial systems can only be swept over their entire wavelength range at less than 10 Hz. This prohibits broadband simultaneous measurements of multiple chemicals in plumes from natural or industrial sources where turbulence and/or chemical reactivity are resulting in rapid changes in chemical composition on sub-1s timescales. At Pacific Northwest National Laboratory we have developed rapidly-swept EC-QCL technology that acquires broadband absorption spectra (~100 cm-1) on ms timescales. The spectral resolution of this system has enabled simultaneous measurement of narrow rotationally-resolved atmospherically-broadened lines from small chemical species, while offering the broad tuning range needed to measure broadband spectral features from multiple large chemical species. In this talk the application of this technology for open-path atmospheric measurements will be discussed based on results from laboratory measurements with simulated plumes of chemicals. The performance offered by the system for simultaneous detection of multiple chemical species will be presented.« less

Demonstration of a Rapidly-Swept External Cavity Quantum Cascade Laser for Atmospheric Sensing Applications

NASA Astrophysics Data System (ADS)

Brumfield, Brian E.; Taubman, Matthew S.; Phillips, Mark C.; Suter, Jonathan D.

2016-06-01

The application of quantum cascade lasers (QCLs) in atmospheric science for trace detection of gases has been demonstrated using sensors in point or remote sensing configurations. Many of these systems utilize single narrowly-tunable (˜10 wn) distributed feedback (DFB-) QCLs that limit simultaneous detection to a restricted number of small chemical species like H2O or N2O. The narrow wavelength range of DFB-QCLs precludes accurate quantification of large chemical species with broad rotationally-unresolved vibrational spectra, such as volatile organic compounds, that play an important role in the chemistry of the atmosphere. External-cavity (EC-) QCL systems are available that offer tuning ranges greater than 100 wn, making them excellent IR sources for measuring multiple small and large chemical species in the atmosphere. While the broad wavelength coverage afforded by an EC system enables measurements of large chemical species, most commercial systems can only be swept over their entire wavelength range at less than 10 Hz. This prohibits broadband simultaneous measurements of multiple chemicals in plumes from natural or industrial sources where turbulence and/or chemical reactivity are resulting in rapid changes in chemical composition on sub-1s timescales. At Pacific Northwest National Laboratory we have developed rapidly-swept EC-QCL technology that acquires broadband absorption spectra (˜100 wn) on ms timescales. The spectral resolution of this system has enabled simultaneous measurement of narrow rotationally-resolved atmospherically-broadened lines from small chemical species, while offering the broad tuning range needed to measure broadband spectral features from multiple large chemical species. In this talk the application of this technology for open-path atmospheric measurements will be discussed based on results from laboratory measurements with simulated plumes of chemicals. The performance offered by the system for simultaneous detection of multiple chemical species will be presented. The Pacific Northwest National Laboratory is operated for the U.S. Department of Energy (DOE) by the Battelle Memorial Institute under Contract No. DE-AC05-76RL01830.

CW-pumped telecom band polarization entangled photon pair generation in a Sagnac interferometer.

PubMed

Li, Yan; Zhou, Zhi-Yuan; Ding, Dong-Sheng; Shi, Bao-Sen

2015-11-02

Polarization entangled photon pair source is widely used in many quantum information processing applications such as teleportation, quantum communications, quantum computation and high precision quantum metrology. We report on the generation of a continuous-wave pumped 1550 nm polarization entangled photon pair source at telecom wavelength using a type-II periodically poled KTiOPO(4) (PPKTP) crystal in a Sagnac interferometer. Hong-Ou-Mandel (HOM) interference measurement yields signal and idler photon bandwidth of 2.4 nm. High quality of entanglement is verified by various kinds of measurements, for example two-photon interference fringes, Bell inequality and quantum states tomography. The source can be tuned over a broad range against temperature or pump power without loss of visibilities. This source will be used in our future experiments such as generation of orbital angular momentum entangled source at telecom wavelength for quantum frequency up-conversion, entanglement based quantum key distributions and many other quantum optics experiments at telecom wavelengths.

Response functions for neutron skyshine analysis

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

Gui, A.A.; Shultis, J.K.; Faw, R.E.

1997-02-01

Neutron and associated secondary photon line-beam response functions (LBRFs) for point monodirectional neutron sources are generated using the MCNP Monte Carlo code for use in neutron skyshine analysis employing the integral line-beam method. The LBRFs are evaluated at 14 neutron source energies ranging from 0.01 to 14 MeV and at 18 emission angles from 1 to 170 deg, as measured from the source-to-detector axis. The neutron and associated secondary photon conical-beam response functions (CBRFs) for azimuthally symmetric neutron sources are also evaluated at 13 neutron source energies in the same energy range and at 13 polar angles of source collimationmore » from 1 to 89 deg. The response functions are approximated by an empirical three-parameter function of the source-to-detector distance. These response function approximations are available for a source-to-detector distance up to 2,500 m and, for the first time, give dose equivalent responses that are required for modern radiological assessments. For the CBRFs, ground correction factors for neutrons and secondary photons are calculated and also approximated by empirical formulas for use in air-over-ground neutron skyshine problems with azimuthal symmetry. In addition, simple procedures are proposed for humidity and atmospheric density corrections.« less

Constraints on Pacific plate kinematics and dynamics with global positioning system measurements

NASA Technical Reports Server (NTRS)

Dixon, T. H.; Golombek, M. P.; Thornton, C. L.

1985-01-01

A measurement program designed to investigate kinematic and dynamic aspects of plate tectonics in the Pacific region by means of satellite observations is proposed. Accuracy studies are summarized showing that for short baselines (less than 100 km), the measuring accuracy of global positioning system (GPS) receivers can be in the centimeter range. For longer baselines, uncertainty in the orbital ephemerides of the GPS satellites could be a major source of error. Simultaneous observations at widely (about 300 km) separated fiducial stations over the Pacific region, should permit an accuracy in the centimeter range for baselines of up to several thousand kilometers. The optimum performance level is based on the assumption of that fiducial baselines are known a priori to the centimeter range. An example fiducial network for a GPS study of the South Pacific region is described.

Subpixelic measurement of large 1D displacements: principle, processing algorithms, performances and software.

PubMed

Guelpa, Valérian; Laurent, Guillaume J; Sandoz, Patrick; Zea, July Galeano; Clévy, Cédric

2014-03-12

This paper presents a visual measurement method able to sense 1D rigid body displacements with very high resolutions, large ranges and high processing rates. Sub-pixelic resolution is obtained thanks to a structured pattern placed on the target. The pattern is made of twin periodic grids with slightly different periods. The periodic frames are suited for Fourier-like phase calculations-leading to high resolution-while the period difference allows the removal of phase ambiguity and thus a high range-to-resolution ratio. The paper presents the measurement principle as well as the processing algorithms (source files are provided as supplementary materials). The theoretical and experimental performances are also discussed. The processing time is around 3 µs for a line of 780 pixels, which means that the measurement rate is mostly limited by the image acquisition frame rate. A 3-σ repeatability of 5 nm is experimentally demonstrated which has to be compared with the 168 µm measurement range.

Subpixelic Measurement of Large 1D Displacements: Principle, Processing Algorithms, Performances and Software

PubMed Central

Guelpa, Valérian; Laurent, Guillaume J.; Sandoz, Patrick; Zea, July Galeano; Clévy, Cédric

2014-01-01

This paper presents a visual measurement method able to sense 1D rigid body displacements with very high resolutions, large ranges and high processing rates. Sub-pixelic resolution is obtained thanks to a structured pattern placed on the target. The pattern is made of twin periodic grids with slightly different periods. The periodic frames are suited for Fourier-like phase calculations—leading to high resolution—while the period difference allows the removal of phase ambiguity and thus a high range-to-resolution ratio. The paper presents the measurement principle as well as the processing algorithms (source files are provided as supplementary materials). The theoretical and experimental performances are also discussed. The processing time is around 3 μs for a line of 780 pixels, which means that the measurement rate is mostly limited by the image acquisition frame rate. A 3-σ repeatability of 5 nm is experimentally demonstrated which has to be compared with the 168 μm measurement range. PMID:24625736

Contributions of long-range and regional atmospheric transport on pesticide concentrations along a transect crossing a mountain divide.

PubMed

Lavin, Karen S; Hageman, Kimberly J

2013-02-05

Twenty-one halogenated legacy and current-use pesticides and pesticide degradation products were measured in pine needles along a coast-to-coast transect that crossed the Southern Alps of New Zealand. Concentration profiles of nine pesticides were used to determine the influence of geographic sources on the atmospheric pesticide burden at the mountain sites. Pesticide concentration profiles were calculated for each source and mountain site by normalizing concentrations (adjusted for temperature at the site and air-needle partitioning) to the sum of all pesticide concentrations at the site. Each mountain site profile was compared to varying mixtures of the potential source profiles to determine the percent contribution of each source. The highest elevation mountain sites were primarily influenced by long-range, synoptic-scale northwesterly winds. Westerly upslope winds had little influence on any of the mountain sites. Easterly upslope winds from the Canterbury Plains, an agricultural region, strongly influenced the mountain sites within close proximity and had progressively less influence with distance.

Applications of the Integrated High-Performance CMOS Image Sensor to Range Finders - from Optical Triangulation to the Automotive Field.

PubMed

Wu, Jih-Huah; Pen, Cheng-Chung; Jiang, Joe-Air

2008-03-13

With their significant features, the applications of complementary metal-oxidesemiconductor (CMOS) image sensors covers a very extensive range, from industrialautomation to traffic applications such as aiming systems, blind guidance, active/passiverange finders, etc. In this paper CMOS image sensor-based active and passive rangefinders are presented. The measurement scheme of the proposed active/passive rangefinders is based on a simple triangulation method. The designed range finders chieflyconsist of a CMOS image sensor and some light sources such as lasers or LEDs. Theimplementation cost of our range finders is quite low. Image processing software to adjustthe exposure time (ET) of the CMOS image sensor to enhance the performance oftriangulation-based range finders was also developed. An extensive series of experimentswere conducted to evaluate the performance of the designed range finders. From theexperimental results, the distance measurement resolutions achieved by the active rangefinder and the passive range finder can be better than 0.6% and 0.25% within themeasurement ranges of 1 to 8 m and 5 to 45 m, respectively. Feasibility tests onapplications of the developed CMOS image sensor-based range finders to the automotivefield were also conducted. The experimental results demonstrated that our range finders arewell-suited for distance measurements in this field.

SU-E-T-413: Examining Acquisition Rate for Using MatriXX Ion Chamber Array to Measure HDR Brachytherapy Treatments

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

Wagar, M; Bhagwat, M; O’Farrell, D

2015-06-15

Purpose: There are unique obstacles to implementing the MatriXX ionchamber array as a QA tool in Brachytherapy given that the device is designed for use in the MV energy range. One of the challenges we investigate is the affect of acquisition rates on dose measurement accuracy for HDR treatment plans. Methods: A treatment plan was optimized in Oncentra Brachy TPS to deliver a planar dose to a 5×5cm region at 10mm depth. The applicator was affixed to the surface of the MatriXX array. The plan was delivered multiple times using a Nucleatron HDR afterloader with a 2.9Ci Ir192 source. Formore » each measurement the sampling rate of the MatriXX movie mode was varied (30ms and 500ms). This experiment was repeated with identical parameters, following a source exchange, with an 11.2Ci Ir192 source. Finally, a single snap measurement was acquired. Analysis was preformed to evaluate the fidelity of the dose delivery for each iteration of the experiment. Evaluation was based on the comparison between the measured and TPS predicted dose. Results: Higher sample rates induce a greater discrepancy between the predicted and measured dose. Delivering the plan using a lower activity source also produced greater discrepancy in the measurement due to the increased delivery time. Analyzing the single snap measurement showed little difference from the 500ms integral dose measurement. Conclusion: The advantage of using movie mode for HDR treatment delivery QA is the ability for real time source tracking in addition to dose measurement. Our analysis indicates that 500ms is an optimal frame rate.« less

Differential Absorption Lidar (DIAL) Measurements of Landfill Methane Emissions

NASA Astrophysics Data System (ADS)

Innocenti, Fabrizio; Robinson, Rod; Gardiner, Tom; Finlayson, Andrew; Connor, Andy

2017-04-01

DIFFERENTIAL ABSORPTION LIDAR (DIAL) MEASURMENTS OF LANDFILL METHANE EMISSIONS F. INNOCENTI *, R.A. ROBINSON *, T.D. GARDINER, A. FINLAYSON *, A. CONNOR* * National Physical Laboratory (NPL), Hampton Road, Teddington, Middlesex, TW11 0LW, United Kingdom Methane is one of the most important gaseous hydrocarbon species for both industrial and environmental reasons. Understanding and quantifying methane emissions to atmosphere is an important element of climate change research. Range-resolved infrared Differential Absorption Lidar (DIAL) measurements provide the means to map and quantify a wide range of different methane sources. DIAL is a powerful technique that can be used to track and quantify plumes emitted from area emission sources such as landfill sites, waste water treatment plants and petrochemical plants. By using lidar (light detection and ranging), the DIAL technique is able to make remote range-resolved single-ended measurements of the actual distribution of target gases in the atmosphere, with no disruption to normal site operational activities. DIAL provides 3D mapping of emission concentrations and quantification of emission rates for a wide range of target gases such as methane. The NPL DIAL laser source is operated alternately at two similar wavelengths. One of these, termed the "on-resonant wavelength", is chosen to be at a wavelength which is absorbed by the target species. The other, the "off-resonant wavelength", is chosen to be at a nearby wavelength which is not absorbed significantly by the target species. The two wavelengths are chosen to be close, so that the atmospheric scattering properties are the same for both wavelengths. They are also chosen so that any differential absorption due to other atmospheric species are minimised. Any measured difference in the returned signals is therefore due to absorption by the target gas. In the typical DIAL measurement configuration the mobile DIAL facility is positioned downwind of the area being investigated. The DIAL laser beam is then scanned in a vertical plane and the distribution of the target gas in the measurement plane is mapped. By combining this information with the wind conditions, the technique provides a direct measure of the emission rate of the target gas and its spatial distribution rather than the path-averaged concentration given by most other optical remote sensing methods. This means that localised, high concentration plumes can be discriminated from broad, low concentration plumes, and that emissions from different sources within an area can be spatially separated and independently quantified. As an example, the localised emission from an engine stack or flare can be separated from the diffuse emission from a capped area. Horizontal scans just above the surface can also be performed and they are generally used to identify emission hot-spots. Over the last decade the NPL DIAL system has carried out landfill emission surveys at over thirty sites in the UK, France and the USA measuring the total site and area-specific emissions from e.g. active areas, capped areas and engine stacks. This history of emissions measurements made with DIAL at landfill sites is testament to the maturity of the technique that can be deployed as reference tool by the waste industry. The DIAL data can be used by the site operators to validate emissions estimates and by the regulators to revise and update the emission inventories.

PUBLIC EXPOSURE TO MULTIPLE RF SOURCES IN GHANA.

PubMed

Deatanyah, P; Abavare, E K K; Menyeh, A; Amoako, J K

2018-03-16

This paper describes an effort to respond to the suggestion in World Health Organization (WHO) research agenda to better quantify potential exposure levels from a range of radiofrequency (RF) sources at 200 public access locations in Ghana. Wide-band measurements were performed-with a spectrum analyser and a log-periodic antenna using three-point spatial averaging method. The overall results represented a maximum of 0.19% of the ICNIRP reference levels for public exposure. These results were generally lower than found in some previous but were 58% (2.0 dB) greater, than found in similar work conducted in the USA. Major contributing sources of RF fields were identified to be FM broadcast and mobile base station sites. Three locations with the greatest measured RF fields could represent potential areas for epidemiological studies.

Developing a spectroradiometer data uncertainty methodology

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

Peterson, Josh; Vignola, Frank; Habte, Aron

The proper calibration and measurement uncertainty of spectral data obtained from spectroradiometers is essential in accurately quantifying the output of photovoltaic (PV) devices. PV cells and modules are initially characterized using solar simulators but field performance is evaluated using natural sunlight. Spectroradiometers are used to measure the spectrum of both these light sources in an effort to understand the spectral dependence of various PV output capabilities. These chains of characterization and measurement are traceable to National Metrology Institutes such as National Institute of Standards and Technology, and therefore there is a need for a comprehensive uncertainty methodology to determine themore » accuracy of spectroradiometer data. In this paper, the uncertainties associated with the responsivity of a spectroradiometer are examined using the Guide to the Expression of Uncertainty in Measurement (GUM) protocols. This is first done for a generic spectroradiometer, and then, to illustrate the methodology, the calibration of a LI-COR 1800 spectroradiometer is performed. The reader should be aware that the implementation of this methodology will be specific to the spectroradiometer being analyzed and the experimental setup that is used. Depending of the characteristics of the spectroradiometer being evaluated additional sources of uncertainty may need to be included, but the general GUM methodology is the same. Several sources of uncertainty are associated with the spectroradiometer responsivity. Major sources of uncertainty associated with the LI-COR spectroradiometer are noise in the signal at wavelengths less than 400 nm. At wavelengths more than 400 nm, the responsivity can vary drastically, and it is dependent on the wavelength of light, the temperature dependence, the angle of incidence, and the azimuthal orientation of the sensor to the light source. As a result, the expanded uncertainties in the responsivity of the LI-COR spectroradiometer in the wavelength range of 400-1050 nm can range from 4% to 14% at the 95% confidence level.« less

Isotopic signatures of anthropogenic CH4 sources in Alberta, Canada

NASA Astrophysics Data System (ADS)

Lopez, M.; Sherwood, O. A.; Dlugokencky, E. J.; Kessler, R.; Giroux, L.; Worthy, D. E. J.

2017-09-01

A mobile system was used for continuous ambient measurements of stable CH4 isotopes (12CH4 and 13CH4) and ethane (C2H6). This system was used during a winter mobile campaign to investigate the CH4 isotopic signatures and the C2H6/CH4 ratios of the main anthropogenic sources of CH4 in the Canadian province of Alberta. Individual signatures were derived from δ13CH4 and C2H6 measurements in plumes arriving from identifiable single sources. Methane emissions from beef cattle feedlots (n = 2) and landfill (n = 1) had δ13CH4 signatures of -66.7 ± 2.4‰ and -55.3 ± 0.2‰, respectively. The CH4 emissions associated with the oil or gas industry had distinct δ13CH4 signatures, depending on the formation process. Emissions from oil storage tanks (n = 5) had δ13CH4 signatures ranging from -54.9 ± 2.9‰ to -60.6 ± 0.6‰ and non-detectable C2H6, characteristic of secondary microbial methanogenesis in oil-bearing reservoirs. In contrast, CH4 emissions associated with natural gas facilities (n = 8) had δ13CH4 signatures ranging from -41.7 ± 0.7‰ to -49.7 ± 0.7‰ and C2H6/CH4 molar ratios of 0.10 for raw natural gas to 0.04 for processed/refined natural gas, consistent with thermogenic origins. These isotopic signatures and C2H6/CH4 ratios have been used for source discrimination in the weekly atmospheric measurements of stable CH4 isotopes over a two-month winter period at the Lac La Biche (LLB) measurement station, located in Alberta, approximately 200 km northeast of Edmonton. The average signature of -59.5 ± 1.4‰ observed at LLB is likely associated with transport of air after passing over oil industry sources located south of the station.

Developing a spectroradiometer data uncertainty methodology

DOE PAGES

Peterson, Josh; Vignola, Frank; Habte, Aron; ...

2017-04-11

The proper calibration and measurement uncertainty of spectral data obtained from spectroradiometers is essential in accurately quantifying the output of photovoltaic (PV) devices. PV cells and modules are initially characterized using solar simulators but field performance is evaluated using natural sunlight. Spectroradiometers are used to measure the spectrum of both these light sources in an effort to understand the spectral dependence of various PV output capabilities. These chains of characterization and measurement are traceable to National Metrology Institutes such as National Institute of Standards and Technology, and therefore there is a need for a comprehensive uncertainty methodology to determine themore » accuracy of spectroradiometer data. In this paper, the uncertainties associated with the responsivity of a spectroradiometer are examined using the Guide to the Expression of Uncertainty in Measurement (GUM) protocols. This is first done for a generic spectroradiometer, and then, to illustrate the methodology, the calibration of a LI-COR 1800 spectroradiometer is performed. The reader should be aware that the implementation of this methodology will be specific to the spectroradiometer being analyzed and the experimental setup that is used. Depending of the characteristics of the spectroradiometer being evaluated additional sources of uncertainty may need to be included, but the general GUM methodology is the same. Several sources of uncertainty are associated with the spectroradiometer responsivity. Major sources of uncertainty associated with the LI-COR spectroradiometer are noise in the signal at wavelengths less than 400 nm. At wavelengths more than 400 nm, the responsivity can vary drastically, and it is dependent on the wavelength of light, the temperature dependence, the angle of incidence, and the azimuthal orientation of the sensor to the light source. As a result, the expanded uncertainties in the responsivity of the LI-COR spectroradiometer in the wavelength range of 400-1050 nm can range from 4% to 14% at the 95% confidence level.« less

First results of a simultaneous measurement of tritium and 14C in an ultra-low-background proportional counter for environmental sources of methane

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

Mace, Emily K.; Aalseth, Craig E.; Day, Anthony R.

Abstract Simultaneous measurement of tritium and 14C would provide an added tool for tracing organic compounds through environmental systems and is possible via beta energy spectroscopy of sample-derived methane in internal-source gas proportional counters. Since the mid-1960’s atmospheric tritium and 14C have fallen dramatically as the isotopic injections from above-ground nuclear testing have been diluted into the ocean and biosphere. In this work, the feasibility of simultaneous tritium and 14C measurements via proportional counters is revisited in light of significant changes in both the atmospheric and biosphere isotopics and the development of new ultra-low-background gas proportional counting capabilities for smallmore » samples (roughly 50 cc methane). A Geant4 Monte Carlo model of a Pacific Northwest National Laboratory (PNNL) proportional counter response to tritium and 14C is used to analyze small samples of two different methane sources to illustrate the range of applicability of contemporary simultaneous measurements and their limitations. Because the two methane sources examined were not sample size limited, we could compare the small-sample measurements performed at PNNL with analysis of larger samples performed at a commercial laboratory. The dual-isotope simultaneous measurement is well matched for methane samples that are atmospheric or have an elevated source of tritium (i.e. landfill gas). For samples with low/modern tritium isotopics (rainwater), commercial separation and counting is a better fit.« less

Using line acceleration to measure false killer whale (Pseudorca crassidens) click and whistle source levels during pelagic longline depredation.

PubMed

Thode, Aaron; Wild, Lauren; Straley, Janice; Barnes, Dustin; Bayless, Ali; O'Connell, Victoria; Oleson, Erin; Sarkar, Jit; Falvey, Dan; Behnken, Linda; Martin, Sean

2016-11-01

False killer whales (Pseudorca crassidens) depredate pelagic longlines in offshore Hawaiian waters. On January 28, 2015 a depredation event was recorded 14 m from an integrated GoPro camera, hydrophone, and accelerometer, revealing that false killer whales depredate bait and generate clicks and whistles under good visibility conditions. The act of plucking bait off a hook generated a distinctive 15 Hz line vibration. Two similar line vibrations detected at earlier times permitted the animal's range and thus signal source levels to be estimated over a 25-min window. Peak power spectral density source levels for whistles (4-8 kHz) were estimated to be between 115 and 130 dB re 1 μPa 2 /Hz @ 1 m. Echolocation click source levels over 17-32 kHz bandwidth reached 205 dB re 1 μPa @ 1 m pk-pk, or 190 dB re 1 μPa @ 1 m (root-mean-square). Predicted detection ranges of the most intense whistles are 10 to 25 km at respective sea states of 4 and 1, with click detection ranges being 5 times smaller than whistles. These detection range analyses provide insight into how passive acoustic monitoring might be used to both quantify and avoid depredation encounters.

VLF Source Localization with a Freely Drifting Sensor Array

DTIC Science & Technology

1992-09-01

Simultaneous Measurement of Infra - sonic Acoustic Particle Velocity and Acoustic Pressure in the Ocean by F-ely Drifting Swallow Floats," IEEEJ. Ocean. Eng., vol...Pacific. Marine Physical Laboratory’s set of nine freely drifting, infrasonic sensors, capable of recording ocean ambient noise in the 1- to 25-Hz range...Terms. 15. Number of Pages, Swallow float, matched-field processing, infrasonic sensor, vlf source localization 153 16. Price Code. 17. Seorlity

Onset of space charge effects in liquid argon ionization chambers

NASA Astrophysics Data System (ADS)

Toggerson, B.; Newcomer, A.; Rutherfoord, J.; Walker, R. B.

2009-09-01

Using a thin-gap liquid argon ionization chamber and Strontium-90 beta sources we have measured ionization currents over a wide range of gap potentials. These precision "HV plateau curves" advance the understanding of liquid argon sampling calorimeter signals, particularly at high ionization rates. The order of magnitude differences in the activities of the beta sources allow us to estimate where the ionization chamber is driven into the space-charge dominated regime.

Measurement Of Trailing Edge Noise using Directional Array and Coherent Output Power Methods

NASA Technical Reports Server (NTRS)

Hutcheson, Florence V.; Brooks, Thomas F.

2002-01-01

The use of a directional array of microphones for the measurement of trailing edge (TE) noise is described. The capabilities of this method are evaluated via measurements of TE noise from a NACA 63-215 airfoil model and from a cylindrical rod. This TE noise measurement approach is compared to one that is based on the cross spectral analysis of output signals from a pair of microphones (COP method). Advantages and limitations of both methods are examined. It is shown that the microphone array can accurately measures TE noise and captures its two-dimensional characteristic over a large frequency range for any TE configuration as long as noise contamination from extraneous sources is within bounds. The COP method is shown to also accurately measure TE noise but over a more limited frequency range that narrows for increased TE thickness. Finally, the applicability and generality of an airfoil self-noise prediction method was evaluated via comparison to the experimental data obtained using the COP and array measurement methods. The predicted and experimental results are shown to agree over large frequency ranges.

Precision CW laser automatic tracking system investigated

NASA Technical Reports Server (NTRS)

Lang, K. T.; Lucy, R. F.; Mcgann, E. J.; Peters, C. J.

1966-01-01

Precision laser tracker capable of tracking a low acceleration target to an accuracy of about 20 microradians rms is being constructed and tested. This laser tracking has the advantage of discriminating against other optical sources and the capability of simultaneously measuring range.

Absolute sensitivity calibration of an extreme ultraviolet spectrometer for tokamak measurements

NASA Astrophysics Data System (ADS)

Guirlet, R.; Schwob, J. L.; Meyer, O.; Vartanian, S.

2017-01-01

An extreme ultraviolet spectrometer installed on the Tore Supra tokamak has been calibrated in absolute units of brightness in the range 10-340 Å. This has been performed by means of a combination of techniques. The range 10-113 Å was absolutely calibrated by using an ultrasoft-X ray source emitting six spectral lines in this range. The calibration transfer to the range 113-182 Å was performed using the spectral line intensity branching ratio method. The range 182-340 Å was calibrated thanks to radiative-collisional modelling of spectral line intensity ratios. The maximum sensitivity of the spectrometer was found to lie around 100 Å. Around this wavelength, the sensitivity is fairly flat in a 80 Å wide interval. The spatial variations of sensitivity along the detector assembly were also measured. The observed trend is related to the quantum efficiency decrease as the angle of the incoming photon trajectories becomes more grazing.

Analysis of Technology for Compact Coherent Lidar

NASA Technical Reports Server (NTRS)

Amzajerdian, Farzin

1997-01-01

In view of the recent advances in the area of solid state and semiconductor lasers has created new possibilities for the development of compact and reliable coherent lidars for a wide range of applications. These applications include: Automated Rendezvous and Capture, wind shear and clear air turbulence detection, aircraft wake vortex detection, and automobile collision avoidance. The work performed by the UAH personnel under this Delivery Order, concentrated on design and analyses of a compact coherent lidar system capable of measuring range and velocity of hard targets, and providing air mass velocity data. The following is the scope of this work. a. Investigate various laser sources and optical signal detection configurations in support of a compact and lightweight coherent laser radar to be developed for precision range and velocity measurements of hard and fuzzy targets. Through interaction with MSFC engineers, the most suitable laser source and signal detection technique that can provide a reliable compact and lightweight laser radar design will be selected. b. Analyze and specify the coherent laser radar system configuration and assist with its optical and electronic design efforts. Develop a system design including its optical layout design. Specify all optical components and provide the general requirements of the electronic subsystems including laser beam modulator and demodulator drivers, detector electronic interface, and the signal processor. c. Perform a thorough performance analysis to predict the system measurement range and accuracy. This analysis will utilize various coherent laser radar sensitivity formulations and different target models.

Probing the Boundaries of the Heliosphere by Analyzing the Temporal Variation of the Polar ENA Flux

NASA Astrophysics Data System (ADS)

Reisenfeld, D. B.; Janzen, P. H.; Bzowski, M.; Dialynas, K.; Funsten, H. O.; Fuselier, S. A.; Karna, N.; Kubiak, M. A.; McComas, D. J.; Schwadron, N.; Sokol, J. M.

2015-12-01

With nearly seven years of IBEX observations, we can now trace the time evolution of heliospheric ENAs through over half a solar cycle. At the north and south ecliptic poles, the spacecraft attitude allows for continuous coverage of the ENA flux; thus, signal from these vantages have much higher statistical accuracy and time resolution than anywhere else in the sky. By assuming pressure balance across the termination shock, and comparing the solar wind dynamic pressure measured at 1 AU with the heliosheath plasma pressure derived from the observed ENA fluxes, we show that the heliosheath pressure measured at the poles correlates well with the solar cycle. The analysis requires time-shifting the ENA measurements to account for the travel time out and back from the heliosheath. The time shifts at the north pole range from 5.1 years at 700 eV, the low end of the IBEX-Hi energy range, to 3.2 years at 4.3 keV, the top IBEX-Hi energy. These time shifts assume a common mean distance to the ENA source region for all energies. For the south pole, the best-fit time shifts range from 4.1 to 2.6 years across the IBEX-Hi energy range. Hence, the ENA source at the south is somewhat closer than at the north, consistent with an asymmetric heliosphere model. We will present the details of this analysis, as well as estimates of the scale size of the heliosheath in the polar directions.

A Measurement of the Millimeter Emission and the Sunyaev-zel'dovich Effect Associated with Low-frequency Radio Sources

NASA Technical Reports Server (NTRS)

Gralla, Megan B.; Crichton, Devin; Marriage, Tobias A.; Mo, Wenli; Aguirre, Paula; Addison, Graeme E.; Asboth, V.; Battaglia, Nick; Bock, James; Bond, J. Richard;

Wireless acquisition of multi-channel seismic data using the Seismobile system

NASA Astrophysics Data System (ADS)

Isakow, Zbigniew

2017-11-01

This paper describes the wireless acquisition of multi-channel seismic data using a specialized mobile system, Seismobile, designed for subsoil diagnostics for transportation routes. The paper presents examples of multi-channel seismic records obtained during system tests in a configuration with 96 channels (4 landstreamers of 24-channel) and various seismic sources. Seismic waves were generated at the same point using different sources: a 5-kg hammer, a Gisco's source with a 90-kg pile-driver, and two other the pile-drivers of 45 and 70 kg. Particular attention is paid to the synchronization of source timing, the measurement of geometry by autonomous GPS systems, and the repeatability of triggering measurements constrained by an accelerometer identifying the seismic waveform. The tests were designed to the registration, reliability, and range of the wireless transmission of survey signals. The effectiveness of the automatic numbering of measuring modules was tested as the system components were arranged and fixed to the streamers. After measurements were completed, the accuracy and speed of data downloading from the internal memory (SDHC 32GB WiFi) was determined. Additionally, the functionality of automatic battery recharging, the maximum survey duration, and the reliability of battery discharge signalling were assessed.

Automated measurement of zebrafish larval movement

PubMed Central

Cario, Clinton L; Farrell, Thomas C; Milanese, Chiara; Burton, Edward A

2011-01-01

Abstract The zebrafish is a powerful vertebrate model that is readily amenable to genetic, pharmacological and environmental manipulations to elucidate the molecular and cellular basis of movement and behaviour. We report software enabling automated analysis of zebrafish movement from video recordings captured with cameras ranging from a basic camcorder to more specialized equipment. The software, which is provided as open-source MATLAB functions, can be freely modified and distributed, and is compatible with multiwell plates under a wide range of experimental conditions. Automated measurement of zebrafish movement using this technique will be useful for multiple applications in neuroscience, pharmacology and neuropsychiatry. PMID:21646414

Automated measurement of zebrafish larval movement.

PubMed

Cario, Clinton L; Farrell, Thomas C; Milanese, Chiara; Burton, Edward A

2011-08-01

The zebrafish is a powerful vertebrate model that is readily amenable to genetic, pharmacological and environmental manipulations to elucidate the molecular and cellular basis of movement and behaviour. We report software enabling automated analysis of zebrafish movement from video recordings captured with cameras ranging from a basic camcorder to more specialized equipment. The software, which is provided as open-source MATLAB functions, can be freely modified and distributed, and is compatible with multiwell plates under a wide range of experimental conditions. Automated measurement of zebrafish movement using this technique will be useful for multiple applications in neuroscience, pharmacology and neuropsychiatry.

Eddy current gauge for monitoring displacement using printed circuit coil

DOEpatents

Visioli, Jr., Armando J.

1977-01-01

A proximity detection system for non-contact displacement and proximity measurement of static or dynamic metallic or conductive surfaces is provided wherein the measurement is obtained by monitoring the change in impedance of a flat, generally spiral-wound, printed circuit coil which is excited by a constant current, constant frequency source. The change in impedance, which is detected as a corresponding change in voltage across the coil, is related to the eddy current losses in the distant conductive material target. The arrangement provides for considerable linear displacement range with increased accuracies, stability, and sensitivity over the entire range.

VOXES: a high precision X-ray spectrometer for diffused sources with HAPG crystals in the 2–20 keV range

NASA Astrophysics Data System (ADS)

Scordo, A.; Curceanu, C.; Miliucci, M.; Shi, H.; Sirghi, F.; Zmeskal, J.

2018-04-01

Bragg spectroscopy is one of the best established experimental methods for high energy resolution X-ray measurements and has been widely used in several fields, going from fundamental physics to quantum mechanics tests, synchrotron radiation and X-FEL applications, astronomy, medicine and industry. However, this technique is limited to the measurement of photons produced from well collimated or point-like sources and becomes quite inefficient for photons coming from extended and diffused sources like those, for example, emitted in the exotic atoms radiative transitions. The VOXES project's goal is to realise a prototype of a high resolution and high precision X-ray spectrometer, using Highly Annealed Pyrolitic Graphite (HAPG) crystals in the Von Hamos configuration, working also for extended sources. The aim is to deliver a cost effective system having an energy resolution at the level of eV for X-ray energies from about 2 keV up to tens of keV, able to perform sub-eV precision measurements with non point-like sources. In this paper, the working principle of VOXES, together with first results, are presented.

Positron annihilation lifetime spectroscopy study of Kapton thin foils

NASA Astrophysics Data System (ADS)

Kanda, G. S.; Ravelli, L.; Löwe, B.; Egger, W.; Keeble, D. J.

2016-01-01

Variable energy positron annihilation lifetime spectroscopy (VE-PALS) experiments on polyimide material Kapton are reported. Thin Kapton foils are widely used in a variety of mechanical, electronic applications. PALS provides a sensitive probe of vacancy-related defects in a wide range of materials, including open volume in polymers. Varying the positron implantation energy enables direct measurement of thin foils. Thin Kapton foils are also commonly used to enclose the positron source material in conventional PALS measurements performed with unmoderated radionuclide sources. The results of depth-profiled positron lifetime measurements on 7.6 μm and 25 μm Kapton foils are reported and determine a dominant 385(1) ps lifetime component. The absence of significant nanosecond lifetime component due to positronium formation is confirmed.

Genetic variation of piperidine alkaloids in Pinus ponderosa: a common garden study

PubMed Central

Gerson, Elizabeth A.; Kelsey, Rick G.; St Clair, J. Bradley

2009-01-01

Background and Aims Previous measurements of conifer alkaloids have revealed significant variation attributable to many sources, environmental and genetic. The present study takes a complementary and intensive, common garden approach to examine genetic variation in Pinus ponderosa var. ponderosa alkaloid production. Additionally, this study investigates the potential trade-off between seedling growth and alkaloid production, and associations between topographic/climatic variables and alkaloid production. Methods Piperidine alkaloids were quantified in foliage of 501 nursery seedlings grown from seed sources in west-central Washington, Oregon and California, roughly covering the western half of the native range of ponderosa pine. A nested mixed model was used to test differences among broad-scale regions and among families within regions. Alkaloid concentrations were regressed on seedling growth measurements to test metabolite allocation theory. Likewise, climate characteristics at the seed sources were also considered as explanatory variables. Key Results Quantitative variation from seedling to seedling was high, and regional variation exceeded variation among families. Regions along the western margin of the species range exhibited the highest alkaloid concentrations, while those further east had relatively low alkaloid levels. Qualitative variation in alkaloid profiles was low. All measures of seedling growth related negatively to alkaloid concentrations on a natural log scale; however, coefficients of determination were low. At best, annual height increment explained 19·4 % of the variation in ln(total alkaloids). Among the climate variables, temperature range showed a negative, linear association that explained 41·8 % of the variation. Conclusions Given the wide geographic scope of the seed sources and the uniformity of resources in the seedlings' environment, observed differences in alkaloid concentrations are evidence for genetic regulation of alkaloid secondary metabolism in ponderosa pine. The theoretical trade-off with seedling growth appeared to be real, however slight. The climate variables provided little evidence for adaptive alkaloid variation, especially within regions. PMID:19010800

PTB’s radiometric scales for UV and VUV source calibration based on synchrotron radiation

NASA Astrophysics Data System (ADS)

Klein, Roman; Kroth, Simone; Paustian, Wolfgang; Richter, Mathias; Thornagel, Reiner

2018-06-01

The radiant intensity of synchrotron radiation can be accurately calculated with classical electrodynamics. This primary realization of the spectral radiant intensity has been used by PTB at several electron storage rings which have been optimized to be operated as primary source standards for the calibration of transfer sources in the spectral range of UV and VUV for almost 30 years. The transfer sources are compared to the primary source standard by means of suitable wavelength-dispersive transfer stations. The spectral range covered by deuterium lamps, which represent transfer sources that are easy to handle, is of particular relevance in practice. Here, we report on developments in the realization and preservation of the radiometric scales for spectral radiant intensity and spectral radiance in the wavelength region from 116 nm to 400 nm, based on a set of deuterium reference lamps, over the last few decades. An inside view and recommendations on the operation of the D2 lamps used for the realization of the radiometric scale are presented. The data has been recently compiled to illustrate the chronological behaviour at various wavelengths. Moreover, an overview of the internal and external validation measurements and intercomparisons is given.

X-ray grating interferometer for materials-science imaging at a low-coherent wiggler source

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

Herzen, Julia; Physics Department and Institute for Medical Engineering, Technische Universitaet Muenchen, 85748 Garching; Donath, Tilman

2011-11-15

X-ray phase-contrast radiography and tomography enable to increase contrast for weakly absorbing materials. Recently, x-ray grating interferometers were developed that extend the possibility of phase-contrast imaging from highly brilliant radiation sources like third-generation synchrotron sources to non-coherent conventional x-ray tube sources. Here, we present the first installation of a three grating x-ray interferometer at a low-coherence wiggler source at the beamline W2 (HARWI II) operated by the Helmholtz-Zentrum Geesthacht at the second-generation synchrotron storage ring DORIS (DESY, Hamburg, Germany). Using this type of the wiggler insertion device with a millimeter-sized source allows monochromatic phase-contrast imaging of centimeter sized objects withmore » high photon flux. Thus, biological and materials-science imaging applications can highly profit from this imaging modality. The specially designed grating interferometer currently works in the photon energy range from 22 to 30 keV, and the range will be increased by using adapted x-ray optical gratings. Our results of an energy-dependent visibility measurement in comparison to corresponding simulations demonstrate the performance of the new setup.« less

Installation of hybrid ion source on the 1-MV LLNL BioAMS spectrometer

PubMed Central

Ognibene, T. J.; Salazar, G. A.

2012-01-01

A second ion source was recently installed onto the LLNL 1-MV AMS spectrometer, which is dedicated to the quantification of 14C and 3H within biochemical samples. This source is unique among the other LLNL cesium sputter ion sources in that it can ionize both gaseous and solid samples. Also, the injection beam line has been designed to directly measure 14C/12C isotope ratios without the need for electrostatic bouncing. Preliminary tests show that this source can ionize transient CO2 gas pulses containing less than 1 ug carbon with approximately 1.5% efficiency. We demonstrate that the measured 14C/12C isotope ratio is largely unaffected by small drifts in the argon stripper gas density. We also determine that a tandem accelerating voltage of 670 kV enables the highest 14C transmission through the system. Finally, we describe a series of performance tests using solid graphite targets spanning nearly 3 orders in magnitude dynamic range and compare the results to our other ion source. PMID:23467295

Disentangling the major source areas for an intense aerosol advection in the Central Mediterranean on the basis of Potential Source Contribution Function modeling of chemical and size distribution measurements

NASA Astrophysics Data System (ADS)

Petroselli, Chiara; Crocchianti, Stefano; Moroni, Beatrice; Castellini, Silvia; Selvaggi, Roberta; Nava, Silvia; Calzolai, Giulia; Lucarelli, Franco; Cappelletti, David

2018-05-01

In this paper, we combined a Potential Source Contribution Function (PSCF) analysis of daily chemical aerosol composition data with hourly aerosol size distributions with the aim to disentangle the major source areas during a complex and fast modulating advection event impacting on Central Italy in 2013. Chemical data include an ample set of metals obtained by Proton Induced X-ray Emission (PIXE), main soluble ions from ionic chromatography and elemental and organic carbon (EC, OC) obtained by thermo-optical measurements. Size distributions have been recorded with an optical particle counter for eight calibrated size classes in the 0.27-10 μm range. We demonstrated the usefulness of the approach by the positive identification of two very different source areas impacting during the transport event. In particular, biomass burning from Eastern Europe and desert dust from Sahara sources have been discriminated based on both chemistry and size distribution time evolution. Hourly BT provided the best results in comparison to 6 h or 24 h based calculations.

Measurement of Thermal Properties of Rocks at Temperature up to 1,000°C with Transient Plane Source Techniques

NASA Astrophysics Data System (ADS)

Kim, S. K.; Lee, Y.

2017-12-01

A set of devices that can measure thermal properties of rocks over a temperature range from room temperature up to 1,000°C with transient plane source techniques (also known as a Hot Disk method) is introduced. It consists of a main control system (e.g., TPS 2500 S from Hot Disk), mica-insulated sensor, tubular furnace, N2 gas supplier, and pressure regulator. The TPS 2500 S is the core instrument designed for precise analysis of thermal transport properties including thermal conductivity, thermal diffusivity, and volumetric heat capacity. The mica-insulated sensor is composed of an insulated nickel double spiral, which is utilized for both transient heating and precise temperature reading; a mica insulator protects the sensor against mechanical and thermal damage at high temperatures. The tubular furnace can hold two rock core samples of 50-mm-diameter and 25-mm-height with increasing temperatures up to 1,000°C. N2 gas supplier and pressure regulator are used to keep the inside the furnace away from oxygen. Thermal properties of most rocks and minerals vary with increasing temperatures. Experimental measurements of thermal properties at high temperatures have been made mostly using laser flash, needle probe, and divided bar methods in the previous researches, and no previous measurements with the Hot Disk method have been reported yet. We report thermal conductivities, thermal diffusivities, and volumetric heat capacities determined by a transient plane heat source method for fused silica and mafic rock samples using the introduced transient plane source apparatus. The thermal properties of fused silica have been measured mainly over the temperature range from ambient temperature to 500°C. The results seem to agree moderately with the previously reported values by Birch and Clark (Am. J. Sci., 1940). We now check the possible causes of measurement errors in our measurements and prepare to measure thermal properties of the mafic rock samples at temperatures up to 1,000°C using the hot disk method.

Directional acoustic measurements by laser Doppler velocimeters. [for jet aircraft noise

NASA Technical Reports Server (NTRS)

Mazumder, M. K.; Overbey, R. L.; Testerman, M. K.

1976-01-01

Laser Doppler velocimeters (LDVs) were used as velocity microphones to measure sound pressure level in the range of 90-130 db, spectral components, and two-point cross correlation functions for acoustic noise source identification. Close agreement between LDV and microphone data is observed. It was concluded that directional sensitivity and the ability to measure remotely make LDVs useful tools for acoustic measurement where placement of any physical probe is difficult or undesirable, as in the diagnosis of jet aircraft noise.

Assessment of ground effects on the propagation of aircraft noise: The T-38A flight experiment

NASA Technical Reports Server (NTRS)

Willshire, W. L., Jr.

1980-01-01

A flight experiment was conducted to investigate air to ground propagation of sound at gazing angles of incidence. A turbojet powered airplane was flown at altitudes ranging from 10 to 160 m over a 20-microphone array positioned over grass and concrete. The dependence of ground effects on frequency, incidence angle, and slant range was determined using two analysis methods. In one method, a microphone close to the flight path is compared to down range microphones. In the other method, comparisons are made between two microphones which were equidistant from the flight path but positioned over the two surfaces. In both methods, source directivity angle was the criterion by which portions of the microphone signals were compared. The ground effects were largest in the frequency range of 200 to 400 Hz and were found to be dependent on incidence angle and slant range. Ground effects measured for angles of incidence greater than 10 deg to 15 deg were near zero. Measured attenuation increased with increasing slant range for slant ranges less than 750 m. Theoretical predictions were found to be in good agreement with the major details of the measured results.

E-Flux2 and SPOT: Validated Methods for Inferring Intracellular Metabolic Flux Distributions from Transcriptomic Data.

PubMed

Kim, Min Kyung; Lane, Anatoliy; Kelley, James J; Lun, Desmond S

2016-01-01

Several methods have been developed to predict system-wide and condition-specific intracellular metabolic fluxes by integrating transcriptomic data with genome-scale metabolic models. While powerful in many settings, existing methods have several shortcomings, and it is unclear which method has the best accuracy in general because of limited validation against experimentally measured intracellular fluxes. We present a general optimization strategy for inferring intracellular metabolic flux distributions from transcriptomic data coupled with genome-scale metabolic reconstructions. It consists of two different template models called DC (determined carbon source model) and AC (all possible carbon sources model) and two different new methods called E-Flux2 (E-Flux method combined with minimization of l2 norm) and SPOT (Simplified Pearson cOrrelation with Transcriptomic data), which can be chosen and combined depending on the availability of knowledge on carbon source or objective function. This enables us to simulate a broad range of experimental conditions. We examined E. coli and S. cerevisiae as representative prokaryotic and eukaryotic microorganisms respectively. The predictive accuracy of our algorithm was validated by calculating the uncentered Pearson correlation between predicted fluxes and measured fluxes. To this end, we compiled 20 experimental conditions (11 in E. coli and 9 in S. cerevisiae), of transcriptome measurements coupled with corresponding central carbon metabolism intracellular flux measurements determined by 13C metabolic flux analysis (13C-MFA), which is the largest dataset assembled to date for the purpose of validating inference methods for predicting intracellular fluxes. In both organisms, our method achieves an average correlation coefficient ranging from 0.59 to 0.87, outperforming a representative sample of competing methods. Easy-to-use implementations of E-Flux2 and SPOT are available as part of the open-source package MOST (http://most.ccib.rutgers.edu/). Our method represents a significant advance over existing methods for inferring intracellular metabolic flux from transcriptomic data. It not only achieves higher accuracy, but it also combines into a single method a number of other desirable characteristics including applicability to a wide range of experimental conditions, production of a unique solution, fast running time, and the availability of a user-friendly implementation.

Single frequency stable VCSEL as a compact source for interferometry and vibrometry

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

Dudzik, Grzegorz; Rzepka, Janusz

2010-05-28

Developing an innovative PS-DAVLL (Polarization Switching DAVLL) method of frequency stabilization, which used a ferroelectric liquid crystal cell as quarter wave plate, rubidium cell and developed ultra-stable current source, allowed to obtain a frequency stability of 10{sup -9}(frequency reproducibility of 1,2centre dot10{sup -8}) and reductions in external dimensions of laser source. The total power consumption is only 1,5 Watt. Because stabilization method used in the frequency standard is insensitive to vibration, the semiconductor laser interferometer was built for measuring range over one meter, which can also be used in industry for the accurate measurement of displacements with an accuracy ofmore » 1[mum/m]. Measurements of the VCSEL laser parameters are important from the standpoint of its use in laser interferometry or vibrometry, like narrow emission line DELTAnu{sub FWHM} = 70[MHz] equivalent of this laser type and stability of linear polarization of VCSEL laser. The undoubted advantage of the constructed laser source is the lack of mode-hopping effect during continuous work of VCSEL.« less

Chemometric Approach to the Calibration of Light Emitting Diode Based Optical Gas Sensors Using High-Resolution Transmission Molecular Absorption Data.

PubMed

Mahbub, Parvez; Leis, John; Macka, Mirek

2018-05-15

Modeling the propagation of light from LED sources is problematic since the emission covers a broad range of wavelengths and thus cannot be considered as monochromatic. Furthermore, the lack of directivity of such sources is also problematic. Both attributes are characteristic of LEDs. Here we propose a HITRAN ( high-resolution transmission molecular absorption database) based chemometric approach that incorporates not-perfect-monochromaticity and spatial directivity of near-infrared (NIR) LED for absorbance calculations in 1-6% methane (CH 4 ) in air, considering CH 4 as a model absorbing gas. We employed the absorbance thus calculated using HITRAN to validate the experimentally measured absorbance of CH 4 . The maximum error between the measured and calculated absorbance values were within 1%. The approach can be generalized as a chemometric calibration technique for measuring gases and gas mixtures that absorb emissions from polychromatic or not-perfect-monochromatic sources, provided the gas concentration, optical path length, as well as blank and attenuated emission spectra of the light source are incorporated into the proposed chemometric approach.

Street-level noise in an urban setting: assessment and contribution to personal exposure.

PubMed

McAlexander, Tara P; Gershon, Robyn R M; Neitzel, Richard L

2015-02-28

The urban soundscape, which represents the totality of noise in the urban setting, is formed from a wide range of sources. One of the most ubiquitous and least studied of these is street-level (i.e., sidewalk) noise. Mainly associated with vehicular traffic, street level noise is hard to ignore and hard to escape. It is also potentially dangerous, as excessive noise from any source is an important risk factor for adverse health effects. This study was conducted to better characterize the urban soundscape and the role of street level noise on overall personal noise exposure in an urban setting. Street-level noise measures were obtained at 99 street sites located throughout New York City (NYC), along with data on time, location, and sources of environmental noise. The relationship between street-level noise measures and potential predictors of noise was analyzed using linear and logistic regression models, and geospatial modeling was used to evaluate spatial trends in noise. Daily durations of street-level activities (time spent standing, sitting, walking and running on streets) were estimated via survey from a sample of NYC community members recruited at NYC street fairs. Street-level noise measurements were then combined with daily exposure durations for each member of the sample to estimate exposure to street noise, as well as exposure to other sources of noise. The mean street noise level was 73.4 dBA, with substantial spatial variation (range 55.8-95.0 dBA). Density of vehicular (road) traffic was significantly associated with excessive street level noise levels. Exposure duration data for street-level noise and other common sources of noise were collected from 1894 NYC community members. Based on individual street-level exposure estimates, and in consideration of all other sources of noise exposure in an urban population, we estimated that street noise exposure contributes approximately 4% to an average individual's annual noise dose. Street-level noise exposure is a potentially important source of overall noise exposure, and the reduction of environmental sources of excessive street- level noise should be a priority for public health and urban planning.

Improved linearity using harmonic error rejection in a full-field range imaging system

NASA Astrophysics Data System (ADS)

Payne, Andrew D.; Dorrington, Adrian A.; Cree, Michael J.; Carnegie, Dale A.

2008-02-01

Full field range imaging cameras are used to simultaneously measure the distance for every pixel in a given scene using an intensity modulated illumination source and a gain modulated receiver array. The light is reflected from an object in the scene, and the modulation envelope experiences a phase shift proportional to the target distance. Ideally the waveforms are sinusoidal, allowing the phase, and hence object range, to be determined from four measurements using an arctangent function. In practice these waveforms are often not perfectly sinusoidal, and in some cases square waveforms are instead used to simplify the electronic drive requirements. The waveforms therefore commonly contain odd harmonics which contribute a nonlinear error to the phase determination, and therefore an error in the range measurement. We have developed a unique sampling method to cancel the effect of these harmonics, with the results showing an order of magnitude improvement in the measurement linearity without the need for calibration or lookup tables, while the acquisition time remains unchanged. The technique can be applied to existing range imaging systems without having to change or modify the complex illumination or sensor systems, instead only requiring a change to the signal generation and timing electronics.

Exploring the Effect of Media, Salinity and Clay on the Thermoelectric Coupling Coefficient in Self-Potential Data

NASA Astrophysics Data System (ADS)

Meyer, C. D.; Revil, A.

2014-12-01

Self-potential is a non-invasive, passive geophysical technique with applications ranging from imaging oil and gas reservoirs to identifying preferential flow paths in earthen embankments. Several cross-coupled flow phenomena contribute to self-potential data, and there is a need to further quantify these various sources to enable better resolution and quantification of self-potential models. Very little research has been done to constrain thermoelectric source mechanisms that contribute to self-potential signals. A laboratory experiment has been designed to investigate the thermoelectric coupling coefficient (CTE) that relates the voltage change per degree centigrade (V/°C) in porous media. This study focuses on a sand tank experiment using a saturated silica sand. To isolate the temperature gradient dependence of self-potential measurements, no hydraulic gradient is applied to the tank, eliminating the streaming potential component of source current. Self-potential and temperature data are recorded while reservoirs of hot and cold water are established on opposite ends of the tank in order to generate thermoelectric source currents. Various thermal gradients ranging from 0 °C to 80 °C over 20 cm are examined for various salinities (10-3M- 1M NaCl), sand grain sizes and clay content to investigate influences on CTE. A short-duration contact of non-polarizing (Pb/PbCl) electrodes is implemented to minimize temperature drift of electrodes during the experiment. Surface self-potential and temperature measurements are made in 30 minute intervals. Initial measurements have revealed non-linear effects, including a decreased CTE as temperature gradient bounds approach 0 °C.

A new broadly tunable (7.4-10.2 eV) laser based VUV light source and its first application to aerosol mass spectrometry

NASA Astrophysics Data System (ADS)

Hanna, S. J.; Campuzano-Jost, P.; Simpson, E. A.; Robb, D. B.; Burak, I.; Blades, M. W.; Hepburn, J. W.; Bertram, A. K.

2009-01-01

A laser based vacuum ultraviolet (VUV) light source using resonance enhanced four wave difference mixing in xenon gas was developed for near threshold ionization of organics in atmospheric aerosol particles. The source delivers high intensity pulses of VUV light (in the range of 1010 to 1013 photons/pulse depending on wavelength, 5 ns FWHM) with a continuously tunable wavelength from 122 nm (10.2 eV) to 168 nm (7.4 eV)E The setup allows for tight (<1 mm2) and precise focusing ([mu]rad pointing angle adjustability), attributes required for single particle detection. The generated VUV is separated from the pump wavelengths by a custom monochromator which ensures high spectral purity and minimizes absorptive losses. The performance of the source was characterized using organic molecules in the gas phase and optimal working conditions are reported. In the gas phase measurements, photoionization efficiency (PIE) curves were collected for seven different organic species with ionization energies spanning the full wavelength range of the VUV source. The measured appearance energies are very close to the literature values of the ionization energies for all seven species. The effectiveness of the source for single particle studies was demonstrated by analysis of individual caffeine aerosols vaporized by a pulsed CO2 laser in an ion trap mass spectrometer. Mass spectra from single particles down to 300 nm in diameter were collected. Excellent signal to noise characteristics for these small particles give a caffeine detection limit of 8 × 105 molecules which is equivalent to a single 75 nm aerosol, or approximately 1.5% of a 300 nm particleE The appearance energy of caffeine originating from the aerosol was also measured and found to be 7.91 ± 0.05 eV, in good agreement with literature values.

Note: A new design for a low-temperature high-intensity helium beam source

NASA Astrophysics Data System (ADS)

Lechner, B. A. J.; Hedgeland, H.; Allison, W.; Ellis, J.; Jardine, A. P.

2013-02-01

A high-intensity supersonic beam source is a key component of any atom scattering instrument, affecting the sensitivity and energy resolution of the experiment. We present a new design for a source which can operate at temperatures as low as 11.8 K, corresponding to a beam energy of 2.5 meV. The new source improves the resolution of the Cambridge helium spin-echo spectrometer by a factor of 5.5, thus extending the accessible timescales into the nanosecond range. We describe the design of the new source and discuss experiments characterizing its performance. Spin-echo measurements of benzene/Cu(100) illustrate its merit in the study of a typical slow-moving molecular adsorbate species.

The supercontinuum laser as a flexible source for quasi-steady state and time resolved fluorescence studies

NASA Astrophysics Data System (ADS)

Fenske, Roger; Näther, Dirk U.; Dennis, Richard B.; Smith, S. Desmond

2010-02-01

Commercial Fluorescence Lifetime Spectrometers have long suffered from the lack of a simple, compact and relatively inexpensive broad spectral band light source that can be flexibly employed for both quasi-steady state and time resolved measurements (using Time Correlated Single Photon Counting [TCSPC]). This paper reports the integration of an optically pumped photonic crystal fibre, supercontinuum source1 (Fianium model SC400PP) as a light source in Fluorescence Lifetime Spectrometers (Edinburgh Instruments FLS920 and Lifespec II), with single photon counting detectors (micro-channel plate photomultiplier and a near-infrared photomultiplier) covering the UV to NIR range. An innovative method of spectral selection of the supercontinuum source involving wedge interference filters is also discussed.

Comparison of spatial and temporal variations in p-PAH, BC, and p-PAH/BC ratio in six US counties

NASA Astrophysics Data System (ADS)

Han, Inkyu; Ramos-Bonilla, Juan P.; Rule, Ana M.; Mihalic, Jana N.; Polyak, Lisa M.; Breysse, Patrick N.; Geyh, Alison S.

2011-12-01

An ambient air monitoring campaign was performed in six counties (Sacramento, CA; Maricopa, AZ; Anoka, MN; Jefferson, KY; Harris, TX; and Pinellas, FL) between January 2008 and September 2009. The purpose of this paper is to compare the spatial and temporal variability of black carbon (BC) and particle-bound polycyclic aromatic hydrocarbons (p-PAHs), across these counties using continuous monitoring instruments - an Aethalometer and a Photoelectric Aerosol Sensor reporting in units of μg m -3 and fA, respectively. We explored temporal trends in these measurements to assess the potential impact of local combustion sources on air quality. Median BC concentrations ranged from 0.13 to 0.53 μg m -3; and median p-PAH values ranged from 0.31 to 4.18 fA. Hourly BC and p-PAH were elevated during morning rush hour and rapidly decreased later in the morning. Nighttime increases in BC and p-PAH were also observed in most counties. Diurnal patterns of BC and p-PAH were different on weekdays compared to weekends. Profiles of hourly ratios of p-PAH/BC in combination with meteorological data can provide insight into potential sources across the sites. Hourly ratios of p-PAH/BC which peaked during early morning and late afternoon hours suggest a dominating contribution of motor vehicle sources in four of the six counties. In two counties, hourly ratios remained elevated for several hours after rush hour and did not show a distinctive peak suggesting additional sources of BC and p-PAH. Such profiles were seen in both Jefferson KY and Harris TX, and may be attributed to coal combustion, petro-chemical industry and shipping activities, respectively. These results suggest that measurements of BC and p-PAH, combined with meteorological information and emission data are potentially useful to identify combustion sources impacting air quality. More research combining BC and p-PAH measurements with detailed source apportionment data is needed to more fully evaluate the utility of these real-time measures.

Satellite measurements of large-scale air pollution - Measurements of forest fire smoke

NASA Technical Reports Server (NTRS)

Ferrare, Richard A.; Kaufman, Yoram J.; Fraser, Robert S.

1990-01-01

The transport, optical properties, total mass, and removal of smoke produced by forest fires in western Canada during late July and early August 1982 are studied using NOAA 7 AVHRR data. Color composite imagery is produced to track the movement of the smoke over Canada and the U.S. as the smoke traveled thousands of km from the source region. Smoke optical thickness, particle size, and single scattering albedo are computed using radiances measured by AVHRR bands 1 and 2. Results show that smoke optical thickness ranged from less that 0.1 to greater than 3.7 and the geometric mean mass radii ranged from 300 to 900 nm. The smoke single scattering albedo ranged from 0.9 to nearly 1.0. The total smoke mass over the eastern U.S. ranged from 0.1 to 0.5 Tg, which is close to the 0.5 Tg estimated from the forest fuel content. The smoke lifetime is estimated to be between 15 and 20 days.

Measurement of the energy distribution of electrons escaping minimum-B ECR plasmas

NASA Astrophysics Data System (ADS)

Izotov, I.; Tarvainen, O.; Skalyga, V.; Mansfeld, D.; Kalvas, T.; Koivisto, H.; Kronholm, R.

2018-02-01

The measurement of the electron energy distribution (EED) of electrons escaping axially from a minimum-B electron cyclotron resonance ion source (ECRIS) is reported. The experimental data were recorded with a room-temperature 14 GHz ECRIS at the JYFL accelerator laboratory. The electrons escaping through the extraction mirror of the ion source were detected with a secondary electron amplifier placed downstream from a dipole magnet serving as an electron spectrometer with 500 eV resolution. It was discovered that the EED in the range of 5-250 keV is strongly non-Maxwellian and exhibits several local maxima below 20 keV energy. It was observed that the most influential ion source operating parameter on the EED is the magnetic field strength, which affected the EED predominantly at energies less than 100 keV. The effects of the microwave power and frequency, ranging from 100 to 600 W and 11 to 14 GHz, respectively, on the EED were found to be less significant. The presented technique and experiments enable the comparison between direct measurement of the EED and results derived from Bremsstrahlung diagnostics, the latter being severely complicated by the non-Maxwellian nature of the EED reported here. The role of RF pitch angle scattering on electron losses and the relation between the EED of the axially escaping electrons and the EED of the confined electrons are discussed.

Real-time ultrawide-band group delay profile monitoring through low-noise incoherent temporal interferometry.

PubMed

Park, Yongwoo; Malacarne, Antonio; Azaña, José

2011-02-28

A simple, highly accurate measurement technique for real-time monitoring of the group delay (GD) profiles of photonic dispersive devices over ultra-broad spectral bandwidths (e.g. an entire communication wavelength band) is demonstrated. The technique is based on time-domain self-interference of an incoherent light pulse after linear propagation through the device under test, providing a measurement wavelength range as wide as the source spectral bandwidth. Significant enhancement in the signal-to-noise ratio of the self-interference signal has been observed by use of a relatively low-noise incoherent light source as compared with the theoretical estimate for a white-noise light source. This fact combined with the use of balanced photo-detection has allowed us to significantly reduce the number of profiles that need to be averaged to reach a targeted GD measurement accuracy, thus achieving reconstruction of the device GD profile in real time. We report highly-accurate monitoring of (i) the group-delay ripple (GDR) profile of a 10-m long chirped fiber Bragg grating over the full C band (~42 nm), and (ii) the group velocity dispersion (GVD) and dispersion slope (DS) profiles of a ~2-km long dispersion compensating fiber module over an ~72-nm wavelength range, both captured at a 15 frames/s video rate update, with demonstrated standard deviations in the captured GD profiles as low as ~1.6 ps.

Instrument Control (iC) – An Open-Source Software to Automate Test Equipment

PubMed Central

Pernstich, K. P.

2012-01-01

It has become common practice to automate data acquisition from programmable instrumentation, and a range of different software solutions fulfill this task. Many routine measurements require sequential processing of certain tasks, for instance to adjust the temperature of a sample stage, take a measurement, and repeat that cycle for other temperatures. This paper introduces an open-source Java program that processes a series of text-based commands that define the measurement sequence. These commands are in an intuitive format which provides great flexibility and allows quick and easy adaptation to various measurement needs. For each of these commands, the iC-framework calls a corresponding Java method that addresses the specified instrument to perform the desired task. The functionality of iC can be extended with minimal programming effort in Java or Python, and new measurement equipment can be addressed by defining new commands in a text file without any programming. PMID:26900522

Instrument Control (iC) - An Open-Source Software to Automate Test Equipment.

PubMed

Pernstich, K P

2012-01-01

It has become common practice to automate data acquisition from programmable instrumentation, and a range of different software solutions fulfill this task. Many routine measurements require sequential processing of certain tasks, for instance to adjust the temperature of a sample stage, take a measurement, and repeat that cycle for other temperatures. This paper introduces an open-source Java program that processes a series of text-based commands that define the measurement sequence. These commands are in an intuitive format which provides great flexibility and allows quick and easy adaptation to various measurement needs. For each of these commands, the iC-framework calls a corresponding Java method that addresses the specified instrument to perform the desired task. The functionality of iC can be extended with minimal programming effort in Java or Python, and new measurement equipment can be addressed by defining new commands in a text file without any programming.

Mass spectrometric measurements of the isotopic anatomies of molecules (Invited)

NASA Astrophysics Data System (ADS)

Eiler, J. M.; Krumwiede, D.; Schlueter, H.

2013-12-01

Site-specific and multiple isotopic substitutions in molecular structures potentially provide an extraordinarily rich set of constraints on their sources, conditions of formation, reaction and transport histories, and perhaps other issues. Examples include carbonate ';clumped isotope' thermometry, clumped isotope measurements of CO2, O2, and, recently, methane, ethane and N2O; site-specific 15N measurements in N2O and 13C and D analyses of fatty acids, sugars, cellulose, food products, and, recently, n-alkanes. Extension of the principles behind these tools to the very large number of isotopologues of complex molecules could potentially lead to new uses of isotope chemistry, similar to proteomics, metabolomics and genomics in their complexity and depth of detail (';isotomics'?). Several technologies are potentially useful for this field, including ';SNIF-NMR', gas source mass spectrometry and IR absorption spectroscopy. However, all well established methods have restrictive limits in the sizes of samples, types of analyzes, and the sorts of isotopologues that can be measured with useful precision. We will present an overview of several emerging instruments and techniques of high-resolution gas source mass spectrometry that may enable study of a large proportion of the isotopologues of a wide range of volatile and semi-volatile compounds, including many organics, with precisions and sample sizes suitable for a range of applications. A variety of isotopologues can be measured by combining information from the Thermo 253 Ultra (a new high resolution, multi-collector gas source mass spectrometer) and the Thermo DFS (a very high resolution single collector, but used here on a novel mode to achieve ~per mil precision ratio measurements), sometimes supplemented by conventional bulk isotopic measurements. It is possible to design methods in which no one of these sources of data meaningfully constrain abundances of specific isotopologues, but their combination fully and precisely constrains a large number. We have assembled a suite of instruments (including the prototype of the Ultra, and a modified version of the DFS that is capable of dual inlet analyses) that make it logistically straightforward to perform such multi-instrument analyses. Examples will be presented documenting the accuracy of these techniques for systems that are independently well known (e.g., isotopologues of methane), and the precision and internal consistency of results for larger, more complex molecules (e.g., a suite of singly and doubly substituted isotopologues of hexane and other moderate-molecular-weight organics).

Systematic review of studies of staffing and quality in nursing homes.

PubMed

Bostick, Jane E; Rantz, Marilyn J; Flesner, Marcia K; Riggs, C Jo

2006-07-01

To evaluate a range of staffing measures and data sources for long-term use in public reporting of staffing as a quality measure in nursing homes. Eighty-seven research articles and government documents published from 1975 to 2003 were reviewed and summarized. Relevant content was extracted and organized around 3 themes: staffing measures, quality measures, and risk adjustment variables. Data sources for staffing information were also identified. There is a proven association between higher total staffing levels (especially licensed staff) and improved quality of care. Studies also indicate a significant relationship between high turnover and poor resident outcomes. Functional ability, pressure ulcers, and weight loss are the most sensitive quality indicators linked to staffing. The best national data sources for staffing and quality include the Minimum Data Set (MDS) and On-line Survey and Certification Automated Records (OSCAR). However, the accuracy of this self-reported information requires further reliability and validity testing. A nationwide instrument needs to be developed to accurately measure staff turnover. Large-scale studies using payroll data to measure staff retention and its impact on resident outcomes are recommended. Future research should use the most nurse-sensitive quality indicators such as pressure ulcers, functional status, and weight loss.

Extended vertical range roughness measurements in non-ideal environments

NASA Astrophysics Data System (ADS)

Creath, Katherine

2011-09-01

This paper describes recent research into developing an extended range dynamic interferometry technique where the range is extended vertically to enhance surface roughness measurements made in non-ideal environments. Utilizing short pulses from two sources on either side of a frame transfer in a CCD sensor, data can be taken fast enough in noisy shop environments to make measurements in the presence of vibration, and air turbulence. A key application of this technique is monitoring of surface roughness of large optics during the polishing process by making in situ measurements from fine grind through to the final polish. It is anticipated that this monitoring can help speed up what is now a very lengthy process. This same technique is applicable to many other types of measurements including MEMS devices, as it is not affected by dispersion in windows covering devices, and for measuring features on flat panel display glass or semiconductor wafers. This paper describes the technique, and presents results of a variety of sample measurements including: bare glass in various states of polish from fine grind to final polish, scratches and pits in a roughened semiconductor wafer, a DMD MEMS device, and various calibration standards. Performance in terms of repeatabilitity of step heights and roughness for this proof of concept is in the +/-2% range.

MIR and FIR Analysis of Inorganic Species in a Single Data Acquisition

NASA Astrophysics Data System (ADS)

Wang, Peng; Shilov, Sergey

2017-06-01

The extension of the mid IR towards the far IR spectral range below 400 \\wn is of great interest for molecular vibrational analysis for inorganic and organometallic chemistry, for geological, pharmaceutical, and physical applications, polymorph screening and crystallinity analysis as well as for matrix isolation spectroscopy. In these cases, the additional far infrared region offers insight to low energy vibrations which are observable only there. This includes inorganic species, lattice vibrations or intermolecular vibrations in the ordered solid state. The spectral range of a FTIR spectrometer is defined by the major optical components such as the source, beamsplitter, and detector. The globar source covers a broad spectral range from 8000 to 20 \\wn. However a bottle neck exists with respect to the beamsplitter and detector. To extend the spectral range further into the far IR and THz spectral ranges, one or more additional far IR beam splitters and detectors have been previously required. Two new optic components have been incorporated in a spectrometer to achieve coverage of both the mid and far infrared in a single scan: a wide range MIR-FIR beam splitter and the wide range DLaTGS detector that utilizes a diamond window. The use of a standard SiC IR source with these components yields a spectral range of 6000 down to 50 \\wn in one step for all types of transmittance, reflectance and ATR measurements. Utilizing the external water cooled mercury arc high power lamp the spectral range can be ultimately extended down to 10 \\wn. Examples of application will include emission in MIR-THz range, identification of pigments, additives in polymers, and polymorphism studies.

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

Jacobs, Daniel C.; Bowman, Judd; Parsons, Aaron R.

We present a catalog of spectral measurements covering a 100-200 MHz band for 32 sources, derived from observations with a 64 antenna deployment of the Donald C. Backer Precision Array for Probing the Epoch of Reionization (PAPER) in South Africa. For transit telescopes such as PAPER, calibration of the primary beam is a difficult endeavor and errors in this calibration are a major source of error in the determination of source spectra. In order to decrease our reliance on an accurate beam calibration, we focus on calibrating sources in a narrow declination range from –46° to –40°. Since sources atmore » similar declinations follow nearly identical paths through the primary beam, this restriction greatly reduces errors associated with beam calibration, yielding a dramatic improvement in the accuracy of derived source spectra. Extrapolating from higher frequency catalogs, we derive the flux scale using a Monte Carlo fit across multiple sources that includes uncertainty from both catalog and measurement errors. Fitting spectral models to catalog data and these new PAPER measurements, we derive new flux models for Pictor A and 31 other sources at nearby declinations; 90% are found to confirm and refine a power-law model for flux density. Of particular importance is the new Pictor A flux model, which is accurate to 1.4% and shows that between 100 MHz and 2 GHz, in contrast with previous models, the spectrum of Pictor A is consistent with a single power law given by a flux at 150 MHz of 382 ± 5.4 Jy and a spectral index of –0.76 ± 0.01. This accuracy represents an order of magnitude improvement over previous measurements in this band and is limited by the uncertainty in the catalog measurements used to estimate the absolute flux scale. The simplicity and improved accuracy of Pictor A's spectrum make it an excellent calibrator in a band important for experiments seeking to measure 21 cm emission from the epoch of reionization.« less

Dense magnetized plasma associated with a fast radio burst.

PubMed

Masui, Kiyoshi; Lin, Hsiu-Hsien; Sievers, Jonathan; Anderson, Christopher J; Chang, Tzu-Ching; Chen, Xuelei; Ganguly, Apratim; Jarvis, Miranda; Kuo, Cheng-Yu; Li, Yi-Chao; Liao, Yu-Wei; McLaughlin, Maura; Pen, Ue-Li; Peterson, Jeffrey B; Roman, Alexander; Timbie, Peter T; Voytek, Tabitha; Yadav, Jaswant K

2015-12-24

Fast radio bursts are bright, unresolved, non-repeating, broadband, millisecond flashes, found primarily at high Galactic latitudes, with dispersion measures much larger than expected for a Galactic source. The inferred all-sky burst rate is comparable to the core-collapse supernova rate out to redshift 0.5. If the observed dispersion measures are assumed to be dominated by the intergalactic medium, the sources are at cosmological distances with redshifts of 0.2 to 1 (refs 10 and 11). These parameters are consistent with a wide range of source models. One fast burst revealed circular polarization of the radio emission, but no linear polarization was detected, and hence no Faraday rotation measure could be determined. Here we report the examination of archival data revealing Faraday rotation in the fast radio burst FRB 110523. Its radio flux and dispersion measure are consistent with values from previously reported bursts and, accounting for a Galactic contribution to the dispersion and using a model of intergalactic electron density, we place the source at a maximum redshift of 0.5. The burst has a much higher rotation measure than expected for this line of sight through the Milky Way and the intergalactic medium, indicating magnetization in the vicinity of the source itself or within a host galaxy. The pulse was scattered by two distinct plasma screens during propagation, which requires either a dense nebula associated with the source or a location within the central region of its host galaxy. The detection in this instance of magnetization and scattering that are both local to the source favours models involving young stellar populations such as magnetars over models involving the mergers of older neutron stars, which are more likely to be located in low-density regions of the host galaxy.

Aeroacoustic Measurements of a Wing-Flap Configuration

NASA Technical Reports Server (NTRS)

Meadows, Kristine R.; Brooks, Thomas F.; Humphreys, William M.; Hunter, William H.; Gerhold, Carl H.

1997-01-01

Aeroacoustic measurements are being conducted to investigate the mechanisms of sound generation in high-lift wing configurations, and initial results are presented. The model is approximately 6 percent of a full scale configuration, and consists of a main element NACA 63(sub 2) - 215 wing section and a 30 percent chord half-span flap. Flow speeds up to Mach 0.17 are tested at Reynolds number up to approximately 1.7 million. Results are presented for a main element at a 16 degree angle of attack, and flap deflection angles of 29 and 39 degrees. The measurement systems developed for this test include two directional arrays used to localize and characterize the noise sources, and an array of unsteady surface pressure transducers used to characterize wave number spectra and correlate with acoustic measurements. Sound source localization maps show that locally dominant noise sources exist on the flap-side edge. The spectral distribution of the noise sources along the flap-side edge shows a decrease in frequency of the locally dominant noise source with increasing distance downstream of the flap leading edge. Spectra are presented which show general spectral characteristics of Strouhal dependent flow-surface interaction noise. However, the appearance of multiple broadband tonal features at high frequency indicates the presence of aeroacoustic phenomenon following different scaling characteristics. The scaling of the high frequency aeroacoustic phenomenon is found to be different for the two flap deflection angles tested. Unsteady surface pressure measurements in the vicinity of the flap edge show high coherence levels between adjacent sensors on the flap-side edge and on the flap edge upper surface in a region which corresponds closely to where the flap-side edge vortex begins to spill over to the flap upper surface. The frequency ranges where these high levels of coherence occur on the flap surface are consistent with the frequency ranges in which dominant features appear in far field acoustic spectra. The consistency of strongly correlated unsteady surface pressures and far field pressure fluctuations suggests the importance of regions on the flap edge in generating sound.

Ipsilateral medial olivocochlear reflex adaptation of the primary-source DPOAE component measured with pulsed tones

NASA Astrophysics Data System (ADS)

Dalhoff, Ernst; Zelle, Dennis; Gummer, Anthony W.

2015-12-01

Measurement of contralateral suppression or ipsilateral adaptation of DPOAE due to the medial olivocochlear reflex (MOCR) in humans has so far been complicated by interference between the two major contributors to a DPOAE signal, namely, the nonlinear and the reflection-source components. For instance, while the MOCR has been shown to act inhibitory to the cochlear amplifier, a considerable share of the measured responses has been reported to be of the excitatory type (e.g. 22% for contralateral adaptation in [11]), and it has been shown that the magnitudes of ipsilateral adaptation as well as contralateral suppression depend on the precise frequency choice relative to the position of dips in the DPOAE fine structure [3, 8]. To separate MOCR effects on both source components, we developed a paradigm consisting of five short f2 pulses presented during a 0.35 s on-period of the f1 primary within blocks of 1.35 s length. The responses at f1 and f2 were cancelled using the primary-tone phase variation technique [13]. In 16 normal-hearing subjects, we measured MOCR-induced ipsilateral adaptation at three near-by frequencies in the DPOAE fine structure, corresponding roughly to characteristic interference states between the two major source components of a DPOAE, i.e. constructive, destructive and quadrature interference. Measurements were performed in the frequency range 1.7 ≤ f2 ≤ 2 kHz, f2/f1 = 1.2, and with moderate primary-tone levels (L2 = 45 dB SPL, L1 = 57 dB SPL). Analysis of the DPOAE time traces showed that the nonlinear component typically presents inhibitory adaptation between the 1st and the 5th pulses (median: 0.92 dB). Fitting a single exponential function to the pooled data yielded adaptation of 1.49 dB. From 26 statistically significant MOCR effects (P < 0.1) ranging between 0.29 and 2.81 dB, no excitatory response was detected. The separation of the DPOAE sources when analysing MOCR effects on ipsilateral DPOAE offers the potential of investigating the human efferent system more specifically than hitherto possible.

Measurement of Neutron Reaction Cross Sections between 8 and 14 MeV

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

Mannhart, Wolf; Schmidt, Dankwart

2005-05-24

Cross-section measurements were performed with special emphasis on access to the 'blind spot' in the neutron energy range from 10 to 13 MeV. The use of a conventional D(d,n) neutron source in combination with TOF measurements of the D(d,np) break-up component allows the precise determination of monoenergetic cross-section data in this range. The procedure is demonstrated with the measurement of the cross sections of 64Zn(n,p)64Cu, 64Zn(n,2n)63Zn, 63Cu(n,2n)62Cu, and 65Cu(n,2n)64Cu. With all reaction products being strong positron emitters, the radioactivity-counting process has been optimised for a perfect registration of the associated annihilation radiation.

Measurement of Neutron Reaction Cross Sections between 8 and 14 MeV

NASA Astrophysics Data System (ADS)

Mannhart, Wolf; Schmidt, Dankwart

2005-05-01

Cross-section measurements were performed with special emphasis on access to the "blind spot" in the neutron energy range from 10 to 13 MeV. The use of a conventional D(d,n) neutron source in combination with TOF measurements of the D(d,np) break-up component allows the precise determination of monoenergetic cross-section data in this range. The procedure is demonstrated with the measurement of the cross sections of 64Zn(n,p)64Cu, 64Zn(n,2n)63Zn, 63Cu(n,2n)62Cu, and 65Cu(n,2n)64Cu. With all reaction products being strong positron emitters, the radioactivity-counting process has been optimised for a perfect registration of the associated annihilation radiation.

Background radiation measurements at high power research reactors

DOE PAGES

Ashenfelter, J.; Yeh, M.; Balantekin, B.; ...

2015-10-23

Research reactors host a wide range of activities that make use of the intense neutron fluxes generated at these facilities. Recent interest in performing measurements with relatively low event rates, e.g. reactor antineutrino detection, at these facilities necessitates a detailed understanding of background radiation fields. Both reactor-correlated and naturally occurring background sources are potentially important, even at levels well below those of importance for typical activities. Here we describe a comprehensive series of background assessments at three high-power research reactors, including γ-ray, neutron, and muon measurements. For each facility we describe the characteristics and identify the sources of the backgroundmore » fields encountered. Furthermore, the general understanding gained of background production mechanisms and their relationship to facility features will prove valuable for the planning of any sensitive measurement conducted therein.« less

Modelling the Contribution of Long-range Transport of Ammonium Nitrates to Urban Air Pollution and Human Exposure in the United Kingdom

NASA Astrophysics Data System (ADS)

Reis, S.; Vieno, M.; Beck, R.; Ots, R.; Moring, A.; Steinle, S.; Heal, M. R.; Doherty, R. M.

2014-12-01

Urban air pollution and its effects on human health remain to be a challenge in spite of substantial reductions in the emissions of air pollutants (e.g. sulphur dioxide, nitrogen oxides) over the past decades in Europe. While primary pollutants play a vital role in urban air pollution, recent model studies highlight and quantify the relevance of long-range transport of secondary pollution (e.g. secondary inorganic aerosols such as ammonium sulphates and nitrates, or ground level ozone) for the exceedance of local air quality limit values in urban areas across Europe. This contribution can be seen in recurring episodes, for instance in spring 2014, with very high levels of fine particulate matter (PM2.5) in Paris, London and other European cities, as well as in elevated background levels throughout the year. While we will focus on the contribution to exceedances of PM2.5 limit values here, this transboundary transport has wider implications for the deposition of reactive nitrogen far from the source as well. As local authorities are tasked with ensuring the attainment of air quality limit values, exceedances caused by long-range transport, with emissions originating from sources outside of their jurisdiction present substantial challenges. Furthermore, while policy measures have successfully addressed emissions from large point sources in the past, and made progress towards reducing pollution from road vehicles, emissions of ammonia from agricultural sources - a key component for the long-range transport of secondary inorganic aerosols - have remained relatively stable in Europe. Using the example of Europe and the UK, we demonstrate in our presentation how atmospheric chemistry transport modelling across different scales (from regional to local) can provide vital insight in the mechanisms of and relative contributions to the formation of secondary inorganic aerosols. In addition, we illustrate how this modelling capability can inform the design of efficient control strategies by quantifying the effect of different policy measures targeted at specific source sectors, and highlight the role of transboundary air pollution to local air pollution challenges.

Imaging using a supercontinuum laser to assess tumors in patients with breast carcinoma

NASA Astrophysics Data System (ADS)

Sordillo, Laura A.; Sordillo, Peter P.; Alfano, R. R.

2016-03-01

The supercontinuum laser light source has many advantages over other light sources, including broad spectral range. Transmission images of paired normal and malignant breast tissue samples from two patients were obtained using a Leukos supercontinuum (SC) laser light source with wavelengths in the second and third NIR optical windows and an IR- CCD InGaAs camera detector (Goodrich Sensors Inc. high response camera SU320KTSW-1.7RT with spectral response between 900 nm and 1,700 nm). Optical attenuation measurements at the four NIR optical windows were obtained from the samples.

The HEAO-A Scanning Modulation Collimator instrument

NASA Technical Reports Server (NTRS)

Roy, A.; Ballas, J.; Jagoda, N.; Mckinnon, P.; Ramsey, A.; Wester, E.

1977-01-01

The Scanning Modulation Collimator X-ray instrument for the HEAO-A satellite was designed to measure celestial radiation in the range between 1 and 15 KeV and to resolve, and correlate, the position of X-ray sources with visible light sources on the celestial sphere to within 5 arc seconds. The positional accuracy is made possible by mechanical collimation of the X-ray sources viewed by the instrument. High sensitivity is provided from two systems each containing four gas filled proportional counters followed by preamplification, signal summing, pulse height analysis, pulse shape discrimination, X-ray event accumulators and telemetry processing electronics.

Open-Source Automated Mapping Four-Point Probe

PubMed Central

Chandra, Handy; Allen, Spencer W.; Oberloier, Shane W.; Bihari, Nupur; Gwamuri, Jephias; Pearce, Joshua M.

2017-01-01

Scientists have begun using self-replicating rapid prototyper (RepRap) 3-D printers to manufacture open source digital designs of scientific equipment. This approach is refined here to develop a novel instrument capable of performing automated large-area four-point probe measurements. The designs for conversion of a RepRap 3-D printer to a 2-D open source four-point probe (OS4PP) measurement device are detailed for the mechanical and electrical systems. Free and open source software and firmware are developed to operate the tool. The OS4PP was validated against a wide range of discrete resistors and indium tin oxide (ITO) samples of different thicknesses both pre- and post-annealing. The OS4PP was then compared to two commercial proprietary systems. Results of resistors from 10 to 1 MΩ show errors of less than 1% for the OS4PP. The 3-D mapping of sheet resistance of ITO samples successfully demonstrated the automated capability to measure non-uniformities in large-area samples. The results indicate that all measured values are within the same order of magnitude when compared to two proprietary measurement systems. In conclusion, the OS4PP system, which costs less than 70% of manual proprietary systems, is comparable electrically while offering automated 100 micron positional accuracy for measuring sheet resistance over larger areas. PMID:28772471

Evaluation of drug content (potency) for compounded and FDA-approved formulations of doxycycline on receipt and after 21 days of storage.

PubMed

KuKanich, Kate; KuKanich, Butch; Slead, Tanner; Warner, Matt

2017-10-01

OBJECTIVE To determine drug content (potency) of compounded doxycycline formulations for veterinary use and of US FDA-approved doxycycline formulations for human use < 24 hours after receipt (day 1) and after 21 days of storage under recommended conditions (day 21). DESIGN Evaluation study. SAMPLE FDA-approved doxycycline tablets (100 mg), capsules (100 mg), and liquid suspension (10 mg/mL) and compounded doxycycline formulations from 3 pharmacies (tablets [25, 100, and 150 mg; 1 product/source], chews [100 mg; 1 product/source], and liquid suspensions or solution [6 mg/mL {2 sources} and 50 mg/mL {1 source}]). PROCEDURES Doxycycline content was measured in 5 samples of each tablet, chew, or capsule formulation and 5 replicates/bottle of liquid formulation on days 1 and 21 by liquid chromatography and compared with US Pharmacopeia acceptable ranges. RESULTS All FDA-approved formulations had acceptable content on days 1 and 21. On day 1, mean doxycycline content for the 3 compounded tablet formulations was 89%, 98%, and 116% (3/5, 5/5, and 1/5 samples within acceptable ranges); day 21 content range was 86% to 112% (1/5, 5/5, and 4/5 samples within acceptable ranges). Day 1 content of chews was 81%, 78%, and 98% (0/5, 0/5, and 5/5 samples within acceptable ranges), and that of compounded liquids was 50%, 52%, and 85% (no results within acceptable ranges). No chews or compounded liquid formulations met USP standards on day 21. CONCLUSIONS AND CLINICAL RELEVANCE FDA-approved doxycycline should be prescribed when possible. Whole tablets yielded the most consistent doxycycline content for compounded formulations.

Hard X-Ray Footprint Source Sized

NASA Technical Reports Server (NTRS)

Dennis, Brian R.; Kontar, E. P.

2010-01-01

RHESSI has detected compact hard (25 - 100 keV) X-ray sources that are <4 arcseconds (FWHM) in extent for certain flares (Dennis and Pernak (2009). These sources are believed to be at magnetic loop footpoints that are known from observations at other wavelengths to be very small. Flare ribbons seen in the W with TRACE, for example, are approx. 1 arcsecond in width, and white light flares show structure at the approx. 1 arcsecond level. However, Kontar and Jeffrey (2010) have shown that the measured extent should be >6 arcseconds, even if the X-ray emitting thick-target source is point-like. This is because of the strong albedo contribution in the measured energy range for a source located at the expected altitude of 1 Mm near the top of the chromosphere. This discrepancy between observations and model predictions may indicate that the source altitude is significantly lower than assumed or that the RHESSI image reconstruction procedures are not sensitive to the more diffuse albedo patch in the presence of a strong compact source. Results will be presented exploring the latter possibility using the Pixon image reconstruction procedure and other methods based on visibilities.

Interference of Photons from a Weak Laser and a Quantum Dot

NASA Astrophysics Data System (ADS)

Ritchie, David; Bennett, Anthony; Patel, Raj; Nicoll, Christine; Shields, Andrew

2010-03-01

We demonstrate two-photon interference from two unsynchronized sources operating via different physical processes [1]. One source is spontaneous emission from the X^- state of an electrically-driven InAs/GaAs single quantum dot with μeV linewidth, the other stimulated emission from a laser with a neV linewidth. We mix the emission from these sources on a balanced non-polarising beam splitter and measure correlations in the photons that exit using Si-avalanche photodiodes and a time-correlated counting card. By periodically switching the polarisation state of the weak laser we simultaneously measure the correlation for parallel and orthogonally polarised sources, corresponding to maximum and minimum degrees of interference. When the two sources have the same intensity, a reduction in the correlation function at time zero for the case of parallel photon sources clearly indicates this interference effect. To quantify the degree of interference, we develop a theory that predicts the correlation function. Data and experiment are then compared for a range of intensity ratios. Based on this analysis we infer a wave-function overlap of 91%, which is remarkable given the fundamental differences between the two sources. [1] Bennett A. J et al Nature Physics, 5, 715--717 (2009).

Performance analysis of a full-field and full-range swept-source OCT system

NASA Astrophysics Data System (ADS)

Krauter, J.; Boettcher, T.; Körner, K.; Gronle, M.; Osten, W.; Passilly, N.; Froehly, L.; Perrin, S.; Gorecki, C.

2015-09-01

In recent years, optical coherence tomography (OCT) became gained importance in medical disciplines like ophthalmology, due to its noninvasive optical imaging technique with micrometer resolution and short measurement time. It enables e. g. the measurement and visualization of the depth structure of the retina. In other medical disciplines like dermatology, histopathological analysis is still the gold standard for skin cancer diagnosis. The EU-funded project VIAMOS (Vertically Integrated Array-type Mirau-based OCT System) proposes a new type of OCT system combined with micro-technologies to provide a hand-held, low-cost and miniaturized OCT system. The concept is a combination of full-field and full-range swept-source OCT (SS-OCT) detection in a multi-channel sensor based on a micro-optical Mirau-interferometer array, which is fabricated by means of wafer fabrication. This paper presents the study of an experimental proof-of-concept OCT system as a one-channel sensor with bulk optics. This sensor is a Linnik-interferometer type with similar optical parameters as the Mirau-interferometer array. A commercial wavelength tunable light source with a center wavelength at 845nm and 50nm spectral bandwidth is used with a camera for parallel OCT A-Scan detection. In addition, the reference microscope objective lens of the Linnik-interferometer is mounted on a piezo-actuated phase-shifter. Phase-shifting interferometry (PSI) techniques are applied for resolving the conjugate complex artifact and consequently contribute to an increase of image quality and depth range. A suppression ratio of the complex conjugate term of 36 dB is shown and a system sensitivity greater than 96 dB could be measured.

Sea-State Dependence of Aerosol Concentration in the Marine Atmospheric Boundary Layer

NASA Astrophysics Data System (ADS)

Lenain, L.; Melville, W. K.

2016-02-01

While sea spray aerosols represent a large portion of the aerosols present in the marine environment, and despite evidence of the importance of surface wave and wave-breaking related processes in the coupling of the ocean with the atmosphere, sea spray source generation functions are traditionally parameterized by the wind speed at 10m. It is clear that unless the wind and wave field are fully developed, the source function will be a function of both wind and wave parameters. In this study, we report on an air-sea interaction experiment, the ONR phase-resolved High-Resolution Air-Sea Interaction experiments (HIRES), conducted off the coast of Northern California in June 2010. Detailed measurements of aerosol number concentration in the Marine Atmospheric Boundary Layer (MABL), at altitudes ranging from as low as 30m and up to 800m AMSL over a broad range of environmental conditions (significant wave height, Hs, of 2 to 4.5m and wind speed at 10m height, U10, of 10 to 18 m/s) collected from an instrumented research aircraft, are presented. Aerosol number densities and volume are computed over a range of particle diameters from 0.1 to 200 µm, while the surface conditions, i.e. significant wave height, moments of the breaker length distribution Λ(c), and wave breaking dissipation, were measured by a suite of electro-optical sensors that included the NASA Airborne Topographic Mapper (ATM). The sea-state dependence of the aerosol concentration in the MABL is evident, ultimately stressing the need to incorporate wave and wave kinematics in the spray source generation functions that are traditionally primarily parameterized by surface winds. A scaling of the measured aerosol volume distribution by wave and atmospheric state variables is proposed.

Wide tuning range wavelength-swept laser with a single SOA at 1020 nm for ultrahigh resolution Fourier-domain optical coherence tomography.

PubMed

Lee, Sang-Won; Song, Hyun-Woo; Jung, Moon-Youn; Kim, Seung-Hwan

2011-10-24

In this study, we demonstrated a wide tuning range wavelength-swept laser with a single semiconductor optical amplifier (SOA) at 1020 nm for ultrahigh resolution, Fourier-domain optical coherence tomography (UHR, FD-OCT). The wavelength-swept laser was constructed with an external line-cavity based on a Littman configuration. An optical wavelength selection filter consisted of a grating, a telescope, and a polygon scanner. Before constructing the optical wavelength selection filter, we observed that the optical power, the spectrum bandwidth, and the center wavelength of the SOA were affected by the temperature of the thermoelectric (TE) cooler in the SOA mount as well as the applied current. Therefore, to obtain a wide wavelength tuning range, we adjusted the temperature of the TE cooler in the SOA mount. When the temperature in the TE cooler was 9 °C, our swept source had a tuning range of 142 nm and a full-width at half-maximum (FWHM) of 121.5 nm at 18 kHz. The measured instantaneous spectral bandwidth (δλ) is 0.085 nm, which was measured by an optical spectrum analyzer with a resolution bandwidth of 0.06 nm. This value corresponds to an imaging depth of 3.1 mm in air. Additionally, the averaged optical power of our swept source was 8.2 mW. In UHR, FD/SS-OCT using our swept laser, the measured axial resolution was 4.0 μm in air corresponding to 2.9 μm in tissue (n = 1.35). The sensitivity was measured to be 93.1 dB at a depth of 100 μm. Finally, we obtained retinal images (macular and optic disk) and a corneal image. © 2011 Optical Society of America

Church Anchor Explosive Sources (SUS) Propagation Measurements

DTIC Science & Technology

1974-12-01

execution of the exercise were carried out by an even larger group . Contributors from ARL/UT Analysis and Interpretation A. L. Anderson S. K. Mitchell T. D...ACODACs) located at sites A, C, :id. D, and a Multielement Super -direc.-tive Array (MESA) located at site E. The primary source track for the data, as shown...estimates, the narrowband spectra for the swot signai dztected in those ranges are inspected to determine the quality cf thb- data. Presumed signals

Parameter estimation for compact binary coalescence signals with the first generation gravitational-wave detector network

NASA Astrophysics Data System (ADS)

Aasi, J.; Abadie, J.; Abbott, B. P.; Abbott, R.; Abbott, T. D.; Abernathy, M.; Accadia, T.; Acernese, F.; Adams, C.; Adams, T.; Addesso, P.; Adhikari, R.; Affeldt, C.; Agathos, M.; Agatsuma, K.; Ajith, P.; Allen, B.; Allocca, A.; Amador Ceron, E.; Amariutei, D.; Anderson, S. B.; Anderson, W. G.; Arai, K.; Araya, M. C.; Ast, S.; Aston, S. M.; Astone, P.; Atkinson, D.; Aufmuth, P.; Aulbert, C.; Aylott, B. E.; Babak, S.; Baker, P.; Ballardin, G.; Ballmer, S.; Bao, Y.; Barayoga, J. C. B.; Barker, D.; Barone, F.; Barr, B.; Barsotti, L.; Barsuglia, M.; Barton, M. A.; Bartos, I.; Bassiri, R.; Bastarrika, M.; Basti, A.; Batch, J.; Bauchrowitz, J.; Bauer, Th. S.; Bebronne, M.; Beck, D.; Behnke, B.; Bejger, M.; Beker, M. G.; Bell, A. S.; Bell, C.; Belopolski, I.; Benacquista, M.; Berliner, J. M.; Bertolini, A.; Betzwieser, J.; Beveridge, N.; Beyersdorf, P. T.; Bhadbade, T.; Bilenko, I. A.; Billingsley, G.; Birch, J.; Biswas, R.; Bitossi, M.; Bizouard, M. A.; Black, E.; Blackburn, J. K.; Blackburn, L.; Blair, D.; Bland, B.; Blom, M.; Bock, O.; Bodiya, T. P.; Bogan, C.; Bond, C.; Bondarescu, R.; Bondu, F.; Bonelli, L.; Bonnand, R.; Bork, R.; Born, M.; Boschi, V.; Bose, S.; Bosi, L.; Bouhou, B.; Braccini, S.; Bradaschia, C.; Brady, P. R.; Braginsky, V. B.; Branchesi, M.; Brau, J. E.; Breyer, J.; Briant, T.; Bridges, D. O.; Brillet, A.; Brinkmann, M.; Brisson, V.; Britzger, M.; Brooks, A. F.; Brown, D. A.; Bulik, T.; Bulten, H. J.; Buonanno, A.; Burguet–Castell, J.; Buskulic, D.; Buy, C.; Byer, R. L.; Cadonati, L.; Cagnoli, G.; Calloni, E.; Camp, J. B.; Campsie, P.; Cannon, K.; Canuel, B.; Cao, J.; Capano, C. D.; Carbognani, F.; Carbone, L.; Caride, S.; Caudill, S.; Cavaglià, M.; Cavalier, F.; Cavalieri, R.; Cella, G.; Cepeda, C.; Cesarini, E.; Chalermsongsak, T.; Charlton, P.; Chassande-Mottin, E.; Chen, W.; Chen, X.; Chen, Y.; Chincarini, A.; Chiummo, A.; Cho, H. S.; Chow, J.; Christensen, N.; Chua, S. S. Y.; Chung, C. T. Y.; Chung, S.; Ciani, G.; Clara, F.; Clark, D. E.; Clark, J. A.; Clayton, J. H.; Cleva, F.; Coccia, E.; Cohadon, P.-F.; Colacino, C. N.; Colla, A.; Colombini, M.; Conte, A.; Conte, R.; Cook, D.; Corbitt, T. R.; Cordier, M.; Cornish, N.; Corsi, A.; Costa, C. A.; Coughlin, M.; Coulon, J.-P.; Couvares, P.; Coward, D. M.; Cowart, M.; Coyne, D. C.; Creighton, J. D. E.; Creighton, T. D.; Cruise, A. M.; Cumming, A.; Cunningham, L.; Cuoco, E.; Cutler, R. M.; Dahl, K.; Damjanic, M.; Danilishin, S. L.; D'Antonio, S.; Danzmann, K.; Dattilo, V.; Daudert, B.; Daveloza, H.; Davier, M.; Daw, E. J.; Dayanga, T.; De Rosa, R.; DeBra, D.; Debreczeni, G.; Degallaix, J.; Del Pozzo, W.; Dent, T.; Dergachev, V.; DeRosa, R.; Dhurandhar, S.; Di Fiore, L.; Di Lieto, A.; Di Palma, I.; Di Paolo Emilio, M.; Di Virgilio, A.; Díaz, M.; Dietz, A.; Donovan, F.; Dooley, K. L.; Doravari, S.; Dorsher, S.; Drago, M.; Drever, R. W. P.; Driggers, J. C.; Du, Z.; Dumas, J.-C.; Dwyer, S.; Eberle, T.; Edgar, M.; Edwards, M.; Effler, A.; Ehrens, P.; Endrőczi, G.; Engel, R.; Etzel, T.; Evans, K.; Evans, M.; Evans, T.; Factourovich, M.; Fafone, V.; Fairhurst, S.; Farr, B. F.; Farr, W. M.; Favata, M.; Fazi, D.; Fehrmann, H.; Feldbaum, D.; Feroz, F.; Ferrante, I.; Ferrini, F.; Fidecaro, F.; Finn, L. S.; Fiori, I.; Fisher, R. P.; Flaminio, R.; Foley, S.; Forsi, E.; Forte, L. A.; Fotopoulos, N.; Fournier, J.-D.; Franc, J.; Franco, S.; Frasca, S.; Frasconi, F.; Frede, M.; Frei, M. A.; Frei, Z.; Freise, A.; Frey, R.; Fricke, T. T.; Friedrich, D.; Fritschel, P.; Frolov, V. V.; Fujimoto, M.-K.; Fulda, P. J.; Fyffe, M.; Gair, J.; Galimberti, M.; Gammaitoni, L.; Garcia, J.; Garufi, F.; Gáspár, M. E.; Gelencser, G.; Gemme, G.; Genin, E.; Gennai, A.; Gergely, L. Á.; Ghosh, S.; Giaime, J. A.; Giampanis, S.; Giardina, K. D.; Giazotto, A.; Gil-Casanova, S.; Gill, C.; Gleason, J.; Goetz, E.; González, G.; Gorodetsky, M. L.; Goßler, S.; Gouaty, R.; Graef, C.; Graff, P. B.; Granata, M.; Grant, A.; Gray, C.; Greenhalgh, R. J. S.; Gretarsson, A. M.; Griffo, C.; Grote, H.; Grover, K.; Grunewald, S.; Guidi, G. M.; Guido, C.; Gupta, R.; Gustafson, E. K.; Gustafson, R.; Hallam, J. M.; Hammer, D.; Hammond, G.; Hanks, J.; Hanna, C.; Hanson, J.; Harms, J.; Harry, G. M.; Harry, I. W.; Harstad, E. D.; Hartman, M. T.; Haster, C.-J.; Haughian, K.; Hayama, K.; Hayau, J.-F.; Heefner, J.; Heidmann, A.; Heintze, M. C.; Heitmann, H.; Hello, P.; Hemming, G.; Hendry, M. A.; Heng, I. S.; Heptonstall, A. W.; Herrera, V.; Heurs, M.; Hewitson, M.; Hild, S.; Hoak, D.; Hodge, K. A.; Holt, K.; Holtrop, M.; Hong, T.; Hooper, S.; Hough, J.; Howell, E. J.; Hughey, B.; Husa, S.; Huttner, S. H.; Huynh-Dinh, T.; Ingram, D. R.; Inta, R.; Isogai, T.; Ivanov, A.; Izumi, K.; Jacobson, M.; James, E.; Jang, Y. J.; Jaranowski, P.; Jesse, E.; Johnson, W. W.; Jones, D. I.; Jones, R.; Jonker, R. J. G.; Ju, L.; Kalmus, P.; Kalogera, V.; Kandhasamy, S.; Kang, G.; Kanner, J. B.; Kasprzack, M.; Kasturi, R.; Katsavounidis, E.; Katzman, W.; Kaufer, H.; Kaufman, K.; Kawabe, K.; Kawamura, S.; Kawazoe, F.; Keitel, D.; Kelley, D.; Kells, W.; Keppel, D. G.; Keresztes, Z.; Khalaidovski, A.; Khalili, F. Y.; Khazanov, E. A.; Kim, B. K.; Kim, C.; Kim, H.; Kim, K.; Kim, N.; Kim, Y. M.; King, P. J.; Kinzel, D. L.; Kissel, J. S.; Klimenko, S.; Kline, J.; Kokeyama, K.; Kondrashov, V.; Koranda, S.; Korth, W. Z.; Kowalska, I.; Kozak, D.; Kringel, V.; Krishnan, B.; Królak, A.; Kuehn, G.; Kumar, P.; Kumar, R.; Kurdyumov, R.; Kwee, P.; Lam, P. K.; Landry, M.; Langley, A.; Lantz, B.; Lastzka, N.; Lawrie, C.; Lazzarini, A.; Le Roux, A.; Leaci, P.; Lee, C. H.; Lee, H. K.; Lee, H. M.; Leong, J. R.; Leonor, I.; Leroy, N.; Letendre, N.; Lhuillier, V.; Li, J.; Li, T. G. F.; Lindquist, P. E.; Litvine, V.; Liu, Y.; Liu, Z.; Lockerbie, N. A.; Lodhia, D.; Logue, J.; Lorenzini, M.; Loriette, V.; Lormand, M.; Losurdo, G.; Lough, J.; Lubinski, M.; Lück, H.; Lundgren, A. P.; Macarthur, J.; Macdonald, E.; Machenschalk, B.; MacInnis, M.; Macleod, D. M.; Mageswaran, M.; Mailand, K.; Majorana, E.; Maksimovic, I.; Malvezzi, V.; Man, N.; Mandel, I.; Mandic, V.; Mantovani, M.; Marchesoni, F.; Marion, F.; Márka, S.; Márka, Z.; Markosyan, A.; Maros, E.; Marque, J.; Martelli, F.; Martin, I. W.; Martin, R. M.; Marx, J. N.; Mason, K.; Masserot, A.; Matichard, F.; Matone, L.; Matzner, R. A.; Mavalvala, N.; Mazzolo, G.; McCarthy, R.; McClelland, D. E.; McGuire, S. C.; McIntyre, G.; McIver, J.; Meadors, G. D.; Mehmet, M.; Meier, T.; Melatos, A.; Melissinos, A. C.; Mendell, G.; Menéndez, D. F.; Mercer, R. A.; Meshkov, S.; Messenger, C.; Meyer, M. S.; Miao, H.; Michel, C.; Milano, L.; Miller, J.; Minenkov, Y.; Mingarelli, C. M. F.; Mitrofanov, V. P.; Mitselmakher, G.; Mittleman, R.; Moe, B.; Mohan, M.; Mohapatra, S. R. P.; Moraru, D.; Moreno, G.; Morgado, N.; Morgia, A.; Mori, T.; Morriss, S. R.; Mosca, S.; Mossavi, K.; Mours, B.; Mow–Lowry, C. M.; Mueller, C. L.; Mueller, G.; Mukherjee, S.; Mullavey, A.; Müller-Ebhardt, H.; Munch, J.; Murphy, D.; Murray, P. G.; Mytidis, A.; Nash, T.; Naticchioni, L.; Necula, V.; Nelson, J.; Neri, I.; Newton, G.; Nguyen, T.; Nishizawa, A.; Nitz, A.; Nocera, F.; Nolting, D.; Normandin, M. E.; Nuttall, L.; Ochsner, E.; O'Dell, J.; Oelker, E.; Ogin, G. H.; Oh, J. J.; Oh, S. H.; Oldenberg, R. G.; O'Reilly, B.; O'Shaughnessy, R.; Osthelder, C.; Ott, C. D.; Ottaway, D. J.; Ottens, R. S.; Overmier, H.; Owen, B. J.; Page, A.; Palladino, L.; Palomba, C.; Pan, Y.; Pankow, C.; Paoletti, F.; Paoletti, R.; Papa, M. A.; Parisi, M.; Pasqualetti, A.; Passaquieti, R.; Passuello, D.; Pedraza, M.; Penn, S.; Perreca, A.; Persichetti, G.; Phelps, M.; Pichot, M.; Pickenpack, M.; Piergiovanni, F.; Pierro, V.; Pihlaja, M.; Pinard, L.; Pinto, I. M.; Pitkin, M.; Pletsch, H. J.; Plissi, M. V.; Poggiani, R.; Pöld, J.; Postiglione, F.; Poux, C.; Prato, M.; Predoi, V.; Prestegard, T.; Price, L. R.; Prijatelj, M.; Principe, M.; Privitera, S.; Prodi, G. A.; Prokhorov, L. G.; Puncken, O.; Punturo, M.; Puppo, P.; Quetschke, V.; Quitzow-James, R.; Raab, F. J.; Rabeling, D. S.; Rácz, I.; Radkins, H.; Raffai, P.; Rakhmanov, M.; Ramet, C.; Rankins, B.; Rapagnani, P.; Raymond, V.; Re, V.; Reed, C. M.; Reed, T.; Regimbau, T.; Reid, S.; Reitze, D. H.; Ricci, F.; Riesen, R.; Riles, K.; Roberts, M.; Robertson, N. A.; Robinet, F.; Robinson, C.; Robinson, E. L.; Rocchi, A.; Roddy, S.; Rodriguez, C.; Rodruck, M.; Rolland, L.; Rollins, J. G.; Romano, R.; Romie, J. H.; Rosińska, D.; Röver, C.; Rowan, S.; Rüdiger, A.; Ruggi, P.; Ryan, K.; Salemi, F.; Sammut, L.; Sandberg, V.; Sankar, S.; Sannibale, V.; Santamaría, L.; Santiago-Prieto, I.; Santostasi, G.; Saracco, E.; Sassolas, B.; Sathyaprakash, B. S.; Saulson, P. R.; Savage, R. L.; Schilling, R.; Schnabel, R.; Schofield, R. M. S.; Schulz, B.; Schutz, B. F.; Schwinberg, P.; Scott, J.; Scott, S. M.; Seifert, F.; Sellers, D.; Sentenac, D.; Sergeev, A.; Shaddock, D. A.; Shaltev, M.; Shapiro, B.; Shawhan, P.; Shoemaker, D. H.; Sidery, T. L.; Siemens, X.; Sigg, D.; Simakov, D.; Singer, A.; Singer, L.; Sintes, A. M.; Skelton, G. R.; Slagmolen, B. J. J.; Slutsky, J.; Smith, J. R.; Smith, M. R.; Smith, R. J. E.; Smith-Lefebvre, N. D.; Somiya, K.; Sorazu, B.; Speirits, F. C.; Sperandio, L.; Stefszky, M.; Steinert, E.; Steinlechner, J.; Steinlechner, S.; Steplewski, S.; Stochino, A.; Stone, R.; Strain, K. A.; Strigin, S. E.; Stroeer, A. S.; Sturani, R.; Stuver, A. L.; Summerscales, T. Z.; Sung, M.; Susmithan, S.; Sutton, P. J.; Swinkels, B.; Szeifert, G.; Tacca, M.; Taffarello, L.; Talukder, D.; Tanner, D. B.; Tarabrin, S. P.; Taylor, R.; ter Braack, A. P. M.; Thomas, P.; Thorne, K. A.; Thorne, K. S.; Thrane, E.; Thüring, A.; Titsler, C.; Tokmakov, K. V.; Tomlinson, C.; Toncelli, A.; Tonelli, M.; Torre, O.; Torres, C. V.; Torrie, C. I.; Tournefier, E.; Travasso, F.; Traylor, G.; Tse, M.; Ugolini, D.; Vahlbruch, H.; Vajente, G.; van den Brand, J. F. J.; Van Den Broeck, C.; van der Putten, S.; van Veggel, A. A.; Vass, S.; Vasuth, M.; Vaulin, R.; Vavoulidis, M.; Vecchio, A.; Vedovato, G.; Veitch, J.; Veitch, P. J.; Venkateswara, K.; Verkindt, D.; Vetrano, F.; Viceré, A.; Villar, A. E.; Vinet, J.-Y.; Vitale, S.; Vocca, H.; Vorvick, C.; Vyatchanin, S. P.; Wade, A.; Wade, L.; Wade, M.; Waldman, S. J.; Wallace, L.; Wan, Y.; Wang, M.; Wang, X.; Wanner, A.; Ward, R. L.; Was, M.; Weinert, M.; Weinstein, A. J.; Weiss, R.; Welborn, T.; Wen, L.; Wessels, P.; West, M.; Westphal, T.; Wette, K.; Whelan, J. T.; Whitcomb, S. E.; White, D. J.; Whiting, B. F.; Wiesner, K.; Wilkinson, C.; Willems, P. A.; Williams, L.; Williams, R.; Willke, B.; Wimmer, M.; Winkelmann, L.; Winkler, W.; Wipf, C. C.; Wiseman, A. G.; Wittel, H.; Woan, G.; Wooley, R.; Worden, J.; Yablon, J.; Yakushin, I.; Yamamoto, H.; Yamamoto, K.; Yancey, C. C.; Yang, H.; Yeaton-Massey, D.; Yoshida, S.; Yvert, M.; Zadrożny, A.; Zanolin, M.; Zendri, J.-P.; Zhang, F.; Zhang, L.; Zhao, C.; Zotov, N.; Zucker, M. E.; Zweizig, J.

2013-09-01

Compact binary systems with neutron stars or black holes are one of the most promising sources for ground-based gravitational-wave detectors. Gravitational radiation encodes rich information about source physics; thus parameter estimation and model selection are crucial analysis steps for any detection candidate events. Detailed models of the anticipated waveforms enable inference on several parameters, such as component masses, spins, sky location and distance, that are essential for new astrophysical studies of these sources. However, accurate measurements of these parameters and discrimination of models describing the underlying physics are complicated by artifacts in the data, uncertainties in the waveform models and in the calibration of the detectors. Here we report such measurements on a selection of simulated signals added either in hardware or software to the data collected by the two LIGO instruments and the Virgo detector during their most recent joint science run, including a “blind injection” where the signal was not initially revealed to the collaboration. We exemplify the ability to extract information about the source physics on signals that cover the neutron-star and black-hole binary parameter space over the component mass range 1M⊙-25M⊙ and the full range of spin parameters. The cases reported in this study provide a snapshot of the status of parameter estimation in preparation for the operation of advanced detectors.

Analysis and prediction of ocean swell using instrumented buoys

NASA Technical Reports Server (NTRS)

Mettlach, Theodore; Wang, David; Wittmann, Paul

1994-01-01

During the period 20-23 September 1990, the remnants of Supertyphoon Flo moved into the central North Pacific Ocean with sustained wind speeds of 28 m/s. The strong wind and large fetch area associated with this storm generated long-period swell that propagated to the west coast of North America. National Data Buoy Center moored-buoy stations, located in a network that ranged from the Gulf of Alaska to the California Bight, provided wave spectral estimates of the swell from this storm. The greatest dominant wave periods measured were approximately 20-25 s, and significant wave heights measured ranged from 3 to 8 m. Wave spectra from an array of three nondirectional buoys are used to find the source of the long-period swell. Directional wave spectra from a heave-pitch-roll buoy are also used to make an independent estimate of the source of the swell. The ridge-line method, using time-frequency contour plots of wave spectral energy density, is used to determine the time of swell generation, which is used with the appropriate surface pressure analysis to infer the swell generation area. The diagnosed sources of the swell are also compared with nowcasts from the Global Spectral Ocean Wave Model of the Fleet Numerical Oceanography Center. A simple method of predicting the propagation of ocean swell, by applying a simple kinematic model of wave propagation to the estimated point and time source, is demonstrated.

Very long baseline interferometer measurements of plasma turbulence in the solar wind

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

Takayuki Sakurai; Spangler, S.R.; Armstrong, J.W.

Turbulence in the solar wind plasma was studied using angular broadening measurements of 10 extragalactic compact radio sources (quasars) with a very long baseline interferometer (VLBI) at 4.99 GHz. Unlike other angular broadening studies, the measured broadening size was corrected for intrinsic source structures which were obtained from a separate VLBI observation. The solar elongations of the sources ranged from 18 R{sub S} to 243 R{sub S}, and five sources with elongations {<=} 60 R{sub S} showed varying degrees of broadening. The measured angular sizes are considerably less than predicted by the well-known empirical relationship of Erickson, as well asmore » two other models for strength of scattering as a function of solar elongation. However, the data are in good agreement with a model for the spatial power spectrum of the turbulence proposed by Coles and Harmon. This model consists of a Kolmogorov spectrum at large scales, but with an enhancement of power near the wavenumber corresponding o the ion inertial length. Two of these sources, 1148-001 and 1253-053 (3C279), show substantial differences in the amount of scattering, even though they are at similar solar elongations (29 versus 35 R{sub S}). Data to which the authors have access indicate that the state of the corona along the lines of sight to these sources may have been quite different. Angular broadening measurements with VLBI interferometers currently under development (primarily the very long baseline array) will allow a global view of plasma turbulence out of the ecliptic plane and thus be complementary to the point in situ measurements with Ulysses. 37 refs., 4 figs., 1 tab.« less

Quantitative Measurements of X-ray Intensity

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

Haugh, M. J., Schneider, M.

This chapter describes the characterization of several X-ray sources and their use in calibrating different types of X-ray cameras at National Security Technologies, LLC (NSTec). The cameras are employed in experimental plasma studies at Lawrence Livermore National Laboratory (LLNL), including the National Ignition Facility (NIF). The sources provide X-rays in the energy range from several hundred eV to 110 keV. The key to this effort is measuring the X-ray beam intensity accurately and traceable to international standards. This is accomplished using photodiodes of several types that are calibrated using radioactive sources and a synchrotron source using methods and materials thatmore » are traceable to the U.S. National Institute of Standards and Technology (NIST). The accreditation procedures are described. The chapter begins with an introduction to the fundamental concepts of X-ray physics. The types of X-ray sources that are used for device calibration are described. The next section describes the photodiode types that are used for measuring X-ray intensity: power measuring photodiodes, energy dispersive photodiodes, and cameras comprising photodiodes as pixel elements. Following their description, the methods used to calibrate the primary detectors, the power measuring photodiodes and the energy dispersive photodiodes, as well as the method used to get traceability to international standards are described. The X-ray source beams can then be measured using the primary detectors. The final section then describes the use of the calibrated X-ray beams to calibrate X-ray cameras. Many of the references are web sites that provide databases, explanations of the data and how it was generated, and data calculations for specific cases. Several general reference books related to the major topics are included. Papers expanding some subjects are cited.« less

Explosion-induced stress changes estimated from vibrating-wire stressmeter measurements near the Mighty Epic event, Nevada Test Site

USGS Publications Warehouse

Ellis, William L.; Kibler, J.D.

1983-01-01

Explosion-induced compressive stress increases near an underground nuclear explosion are believed to contribute significantly to the containment of high-pressure gases within the explosion-produced cavity. These induced compressive stresses are predicted by computer calculations, but have never been adequately confirmed by field measurements, owing primarily to the unique difficulties of obtaining such field data. Vibrating-wire stressmeter measurements made near the Mighty Epic nuclear detonation, however, qualitatively indicate that within 150 meters of the working point, permanent compressive stress increases of several megapascals were present 15 weeks after the event. Additionally, stress-change magnitudes interpreted from the stressmeter data between the 75- and 260-meter range from the working point compare favorably with calculational predictions of the stress changes believed to be present shortly after detonation of the event. The measurements and calculations differ, however, with regard to the pattern of stress change radial and transverse to the explosion source. For the range of the field measurements from the working point, computer models predict the largest compressive-stress increase to be radial to the explosion source, while the field data indicate the transverse component of. stress change to be the most compressive. The significance of time-dependent modification of the initial explosion-induced stress distribution is, however, uncertain with regard to the comparison of the field measurements and theoretical predictions.

Electroinduction disk sensor of electric field strength

NASA Astrophysics Data System (ADS)

Biryukov, S. V.; Korolyova, M. A.

2018-01-01

Measurement of the level of electric fields exposure to the technical and biological objects for a long time is an urgent task. To solve this problem, the required electric field sensors with specified metrological characteristics. The aim of the study is the establishment of theoretical assumptions for the calculation of the flat electric field sensors. It is proved that the accuracy of the sensor does not exceed 3% in the spatial range 0

Temporal information partitioning: Characterizing synergy, uniqueness, and redundancy in interacting environmental variables

NASA Astrophysics Data System (ADS)

Goodwell, Allison E.; Kumar, Praveen

2017-07-01

Information theoretic measures can be used to identify nonlinear interactions between source and target variables through reductions in uncertainty. In information partitioning, multivariate mutual information is decomposed into synergistic, unique, and redundant components. Synergy is information shared only when sources influence a target together, uniqueness is information only provided by one source, and redundancy is overlapping shared information from multiple sources. While this partitioning has been applied to provide insights into complex dependencies, several proposed partitioning methods overestimate redundant information and omit a component of unique information because they do not account for source dependencies. Additionally, information partitioning has only been applied to time-series data in a limited context, using basic pdf estimation techniques or a Gaussian assumption. We develop a Rescaled Redundancy measure (Rs) to solve the source dependency issue, and present Gaussian, autoregressive, and chaotic test cases to demonstrate its advantages over existing techniques in the presence of noise, various source correlations, and different types of interactions. This study constitutes the first rigorous application of information partitioning to environmental time-series data, and addresses how noise, pdf estimation technique, or source dependencies can influence detected measures. We illustrate how our techniques can unravel the complex nature of forcing and feedback within an ecohydrologic system with an application to 1 min environmental signals of air temperature, relative humidity, and windspeed. The methods presented here are applicable to the study of a broad range of complex systems composed of interacting variables.

Calculated and measured brachytherapy dosimetry parameters in water for the Xoft Axxent X-Ray Source: an electronic brachytherapy source.

PubMed

Rivard, Mark J; Davis, Stephen D; DeWerd, Larry A; Rusch, Thomas W; Axelrod, Steve

2006-11-01

A new x-ray source, the model S700 Axxent X-Ray Source (Source), has been developed by Xoft Inc. for electronic brachytherapy. Unlike brachytherapy sources containing radionuclides, this Source may be turned on and off at will and may be operated at variable currents and voltages to change the dose rate and penetration properties. The in-water dosimetry parameters for this electronic brachytherapy source have been determined from measurements and calculations at 40, 45, and 50 kV settings. Monte Carlo simulations of radiation transport utilized the MCNP5 code and the EPDL97-based mcplib04 cross-section library. Inter-tube consistency was assessed for 20 different Sources, measured with a PTW 34013 ionization chamber. As the Source is intended to be used for a maximum of ten treatment fractions, tube stability was also assessed. Photon spectra were measured using a high-purity germanium (HPGe) detector, and calculated using MCNP. Parameters used in the two-dimensional (2D) brachytherapy dosimetry formalism were determined. While the Source was characterized as a point due to the small anode size, < 1 mm, use of the one-dimensional (1D) brachytherapy dosimetry formalism is not recommended due to polar anisotropy. Consequently, 1D brachytherapy dosimetry parameters were not sought. Calculated point-source model radial dose functions at gP(5) were 0.20, 0.24, and 0.29 for the 40, 45, and 50 kV voltage settings, respectively. For 1

Spectro-refractometry of individual microscopic objects using swept-source quantitative phase imaging.

PubMed

Jung, Jae-Hwang; Jang, Jaeduck; Park, Yongkeun

2013-11-05

We present a novel spectroscopic quantitative phase imaging technique with a wavelength swept-source, referred to as swept-source diffraction phase microscopy (ssDPM), for quantifying the optical dispersion of microscopic individual samples. Employing the swept-source and the principle of common-path interferometry, ssDPM measures the multispectral full-field quantitative phase imaging and spectroscopic microrefractometry of transparent microscopic samples in the visible spectrum with a wavelength range of 450-750 nm and a spectral resolution of less than 8 nm. With unprecedented precision and sensitivity, we demonstrate the quantitative spectroscopic microrefractometry of individual polystyrene beads, 30% bovine serum albumin solution, and healthy human red blood cells.

The efficient model to define a single light source position by use of high dynamic range image of 3D scene

NASA Astrophysics Data System (ADS)

Wang, Xu-yang; Zhdanov, Dmitry D.; Potemin, Igor S.; Wang, Ying; Cheng, Han

2016-10-01

One of the challenges of augmented reality is a seamless combination of objects of the real and virtual worlds, for example light sources. We suggest a measurement and computation models for reconstruction of light source position. The model is based on the dependence of luminance of the small size diffuse surface directly illuminated by point like source placed at a short distance from the observer or camera. The advantage of the computational model is the ability to eliminate the effects of indirect illumination. The paper presents a number of examples to illustrate the efficiency and accuracy of the proposed method.

Quantitative shear wave optical coherence elastography (SW-OCE) with acoustic radiation force impulses (ARFI) induced by phase array transducer

NASA Astrophysics Data System (ADS)

Song, Shaozhen; Le, Nhan Minh; Wang, Ruikang K.; Huang, Zhihong

2015-03-01

Shear Wave Optical Coherence Elastography (SW-OCE) uses the speed of propagating shear waves to provide a quantitative measurement of localized shear modulus, making it a valuable technique for the elasticity characterization of tissues such as skin and ocular tissue. One of the main challenges in shear wave elastography is to induce a reliable source of shear wave; most of nowadays techniques use external vibrators which have several drawbacks such as limited wave propagation range and/or difficulties in non-invasive scans requiring precisions, accuracy. Thus, we propose linear phase array ultrasound transducer as a remote wave source, combined with the high-speed, 47,000-frame-per-second Shear-wave visualization provided by phase-sensitive OCT. In this study, we observed for the first time shear waves induced by a 128 element linear array ultrasound imaging transducer, while the ultrasound and OCT images (within the OCE detection range) were triggered simultaneously. Acoustic radiation force impulses are induced by emitting 10 MHz tone-bursts of sub-millisecond durations (between 50 μm - 100 μm). Ultrasound beam steering is achieved by programming appropriate phase delay, covering a lateral range of 10 mm and full OCT axial (depth) range in the imaging sample. Tissue-mimicking phantoms with agarose concentration of 0.5% and 1% was used in the SW-OCE measurements as the only imaging samples. The results show extensive improvements over the range of SW-OCE elasticity map; such improvements can also be seen over shear wave velocities in softer and stiffer phantoms, as well as determining the boundary of multiple inclusions with different stiffness. This approach opens up the feasibility to combine medical ultrasound imaging and SW-OCE for high-resolution localized quantitative measurement of tissue biomechanical property.

Plasma parameter diagnosis using hydrogen emission spectra of a quartz-chamber 2.45 GHz ECRIS at Peking University

NASA Astrophysics Data System (ADS)

Wu, WenBin; Ren, HaiTao; Peng, ShiXiang; Xu, Yuan; Wen, JiaMei; Zhang, Tao; Zhang, JingFeng; Zhang, AiLin; Sun, Jiang; Guo, ZhiYu; Chen, JiaEr

2018-04-01

A quartz-chamber 2.45 GHz electron cyclotron resonance ion source (ECRIS) was designed for diagnostic purposes at Peking University [Patent Number: ZL 201110026605.4]. This ion source can produce a maximum 84 mA hydrogen ion beam at 50 kV with a duty factor of 10%. The root-mean-square (RMS) emittance of this beam is less than 0.12π mm mrad. In our initial work, the electron temperature and electron density inside the plasma chamber had been measured with the line intensity ratio of noble gases. Based on these results, the atomic and molecular emission spectra of hydrogen were applied to determine the dissociation degree of hydrogen and the vibrational temperature of hydrogen molecules in the ground state, respectively. Measurements were performed at gas pressures from 4×10-4 to 1×10-3 Pa and at input peak RF power ranging from 1000 to 1800 W. The dissociation degree of hydrogen in the range of 0.5%-10% and the vibrational temperature of hydrogen molecules in the ground state in the range of 3500-8500 K were obtained. The plasma processes inside this ECRIS chamber were discussed based on these results.

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.

Variation of Lunar Sodium During Passage of the Moon through the Earth's Magnetotail

NASA Technical Reports Server (NTRS)

Potter, Andrew E.; Killen, Rosemary M.; Morgan, Thomas H.

2000-01-01

We measured sodium emission above the lunar equator over a range of lunar altitudes from 100 to 4000 km. The measurements were repeated approximately every 24 hours from June 7 to 16, 1998, covering the period during which the Moon passed through the Earth's magnetotail. Sodium temperatures derived from the altitude dependence of emission intensity ranged from 1200 to 2900 K. This result supports the view that photodesorption is a primary source of sodium in the exosphere since the most probable temperature of sodium form this source is in this range. Passage of the Moon through the Earth's magnetotail (where solar wind is essentially absent) affected the sodium density, such that it was higher before the Moon entered the Earth's magnetotail than after the Moon left it. This suggests that the solar wind plays a role in production of lunar sodium. We propose that its function is to mobilize sodium and bring it to the surface, where photodesorption can eject it into the exosphere. A two-step process such as this could help to explain the latitude dependence of sodium density, which varies as the second or higher power of cosine latitude.

Microbial Breakdown of Organic Carbon in the Diverse Sediments of Guaymas Basin

NASA Astrophysics Data System (ADS)

Hoarfrost, A.; Snider, R.; Arnosti, C.

2015-12-01

Guaymas Basin is characterized by sediments under conditions ranging from hemipelagic to hydrothermal. This wide range in geochemical contexts results in diverse microbial communities that may have varying abilities to access organic matter. We can address these functional differences by comparing enzyme activities initializing the breakdown of organic matter across these sediment types; however, previous direct measurements of the extracellular hydrolysis of complex organic carbon in sediments are sparse. We measured this first step of heterotrophic processing of organic matter in sediments at 5-10cm and 55-60cm depth from a wide range of environmental settings in Guaymas Basin. Sediment sources included sulfidic seeps on the Sonora Margin, hemipelagic ridge flank sediments, and hydrothermically altered Sonora Margin sediments bordering a methane seep site. Hydrolysis of organic substrates varied by depth and by sediment source, but despite high energy potential and organic carbon load in sulfidic sediments, activity was not highest where hydrothermal influence was highest. These results suggest that heterotrophic breakdown of organic carbon in Guaymas Basin sediments may be sensitive to factors including varying composition of organic carbon available in different sediment types, or differences in microbial community capacities to access specific organic substrates.

Photon-Limited Information in High Resolution Laser Ranging

DTIC Science & Technology

2014-05-28

entangled photons generated by spontaneous parametric down-conversion of a chirped source to perform ranging measurements. Summary of the Most... Matlab program to collect the photon counts from the time to digital converter (TDC). This entailed setting up Matlab to talk to the TDC to get the...SECURITY CLASSIFICATION OF: This project is an effort under the Information in a Photon (InPho) program at DARPA\\DSO. Its purpose is to investigate

THE CORES OF THE Fe K{alpha} LINES IN ACTIVE GALACTIC NUCLEI: AN EXTENDED CHANDRA HIGH ENERGY GRATING SAMPLE

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

Shu, X. W.; Wang, J. X.; Yaqoob, T.

We extend the study of the core of the Fe K{alpha} emission line at {approx}6.4 keV in Seyfert galaxies reported by Yaqoob and Padmanabhan using a larger sample observed by the Chandra high-energy grating (HEG). The sample consists of 82 observations of 36 unique sources with z < 0.3. Whilst heavily obscured active galactic nuclei are excluded from the sample, these data offer some of the highest precision measurements of the peak energy of the Fe K{alpha} line, and the highest spectral resolution measurements of the width of the core of the line in unobscured and moderately obscured (N {submore » H} < 10{sup 23} cm{sup -2}) Seyfert galaxies to date. From an empirical and uniform analysis, we present measurements of the Fe K{alpha} line centroid energy, flux, equivalent width (EW), and intrinsic width (FWHM). The Fe K{alpha} line is detected in 33 sources, and its centroid energy is constrained in 32 sources. In 27 sources, the statistical quality of the data is good enough to yield measurements of the FWHM. We find that the distribution in the line centroid energy is strongly peaked around the value for neutral Fe, with over 80% of the observations giving values in the range 6.38-6.43 keV. Including statistical errors, 30 out of 32 sources ({approx}94%) have a line centroid energy in the range 6.35-6.47 keV. The mean EW, among the observations in which a non-zero lower limit could be measured, was 53 {+-} 3 eV. The mean FWHM from the subsample of 27 sources was 2060 {+-} 230 km s{sup -1}. The mean EW and FWHM are somewhat higher when multiple observations for a given source are averaged. From a comparison with the H{beta} optical emission-line widths (or, for one source, Br{alpha}), we find that there is no universal location of the Fe K{alpha} line-emitting region relative to the optical broad-line region (BLR). In general, a given source may have contributions to the Fe K{alpha} line flux from parsec-scale distances from the putative black hole, down to matter a factor {approx}2 closer to the black hole than the BLR. We confirm the presence of the X-ray Baldwin effect, an anti-correlation between the Fe K{alpha} line EW and X-ray continuum luminosity. The HEG data have enabled isolation of this effect to the narrow core of the Fe K{alpha} line.« less

Quantified, Interactive Simulation of AMCW ToF Camera Including Multipath Effects

PubMed Central

Lambers, Martin; Kolb, Andreas

2017-01-01

In the last decade, Time-of-Flight (ToF) range cameras have gained increasing popularity in robotics, automotive industry, and home entertainment. Despite technological developments, ToF cameras still suffer from error sources such as multipath interference or motion artifacts. Thus, simulation of ToF cameras, including these artifacts, is important to improve camera and algorithm development. This paper presents a physically-based, interactive simulation technique for amplitude modulated continuous wave (AMCW) ToF cameras, which, among other error sources, includes single bounce indirect multipath interference based on an enhanced image-space approach. The simulation accounts for physical units down to the charge level accumulated in sensor pixels. Furthermore, we present the first quantified comparison for ToF camera simulators. We present bidirectional reference distribution function (BRDF) measurements for selected, purchasable materials in the near-infrared (NIR) range, craft real and synthetic scenes out of these materials and quantitatively compare the range sensor data. PMID:29271888

Quantified, Interactive Simulation of AMCW ToF Camera Including Multipath Effects.

PubMed

Bulczak, David; Lambers, Martin; Kolb, Andreas

2017-12-22

In the last decade, Time-of-Flight (ToF) range cameras have gained increasing popularity in robotics, automotive industry, and home entertainment. Despite technological developments, ToF cameras still suffer from error sources such as multipath interference or motion artifacts. Thus, simulation of ToF cameras, including these artifacts, is important to improve camera and algorithm development. This paper presents a physically-based, interactive simulation technique for amplitude modulated continuous wave (AMCW) ToF cameras, which, among other error sources, includes single bounce indirect multipath interference based on an enhanced image-space approach. The simulation accounts for physical units down to the charge level accumulated in sensor pixels. Furthermore, we present the first quantified comparison for ToF camera simulators. We present bidirectional reference distribution function (BRDF) measurements for selected, purchasable materials in the near-infrared (NIR) range, craft real and synthetic scenes out of these materials and quantitatively compare the range sensor data.

Grating-assisted demodulation of interferometric optical sensors.

PubMed

Yu, Bing; Wang, Anbo

2003-12-01

Accurate and dynamic control of the operating point of an interferometric optical sensor to produce the highest sensitivity is crucial in the demodulation of interferometric optical sensors to compensate for manufacturing errors and environmental perturbations. A grating-assisted operating-point tuning system has been designed that uses a diffraction grating and feedback control, functions as a tunable-bandpass optical filter, and can be used as an effective demodulation subsystem in sensor systems based on optical interferometers that use broadband light sources. This demodulation method has no signal-detection bandwidth limit, a high tuning speed, a large tunable range, increased interference fringe contrast, and the potential for absolute optical-path-difference measurement. The achieved 40-nm tuning range, which is limited by the available source spectrum width, 400-nm/s tuning speed, and a step resolution of 0.4 nm, is sufficient for most practical measurements. A significant improvement in signal-to-noise ratio in a fiber Fabry-Perot acoustic-wave sensor system proved that the expected fringe contrast and sensitivity increase.

Organic Light-Emitting Diode-on-Silicon Pixel Circuit Using the Source Follower Structure with Active Load for Microdisplays

NASA Astrophysics Data System (ADS)

Kwak, Bong-Choon; Lim, Han-Sin; Kwon, Oh-Kyong

2011-03-01

In this paper, we propose a pixel circuit immune to the electrical characteristic variation of organic light-emitting diodes (OLEDs) for organic light-emitting diode-on-silicon (OLEDoS) microdisplays with a 0.4 inch video graphics array (VGA) resolution and a 6-bit gray scale. The proposed pixel circuit is implemented using five p-channel metal oxide semiconductor field-effect transistors (MOSFETs) and one storage capacitor. The proposed pixel circuit has a source follower with a diode-connected transistor as an active load for improving the immunity against the electrical characteristic variation of OLEDs. The deviation in the measured emission current ranges from -0.165 to 0.212 least significant bit (LSB) among 11 samples while the anode voltage of OLED is 0 V. Also, the deviation in the measured emission current ranges from -0.262 to 0.272 LSB in pixel samples, while the anode voltage of OLED varies from 0 to 2.5 V owing to the electrical characteristic variation of OLEDs.

Semiconductor and thermoluminescent dosimetry of pulsed soft X ray plasma sources.

PubMed

Krása, J; Cejnarová, A; Juha, L; Ryć, L; Scholz, M; Kubes, P

2002-01-01

A multichannel detection system having a dynamic range of approximately 1 x 10(-9) Gy --20 Gy was developed with the use of commercially produced Si-photodiodes and TLDs for accurate measurement of X ray energy emitted from plasma-focus facility and from laser-produced plasmas. The proof of linearity of the employed detectors accomplished by a comparison of their responses to a broad band spectrum of X rays emitted from plasmas, is reported. It is demonstrated that TLDs irradiated with no protective filter show an incorrect response due to overloading in the sub-keV range and repopulation of dosimetric peaks induced by the UV radiation. The measurement of the power of undesirable secondary X ray sources driven by the primary plasma inside the interaction chamber was performed on the basis of analysis of space dependence of X ray intensity with respect to the assumed r(-2) decrease in the intensity far away from the plasma.

Tracing chlorine sources of thermal and mineral springs along and across the Cascade Range using halogen and chlorine isotope compositions

USGS Publications Warehouse

Cullen, Jeffrey T.; Barnes, Jaime D.; Hurwitz, Shaul; Leeman, William P.

2015-01-01

In order to provide constraints on the sources of chlorine in spring waters associated with arc volcanism, the major/minor element concentrations and stable isotope compositions of chlorine, oxygen, and hydrogen were measured in 28 thermal and mineral springs along the Cascade Range in northwestern USA. Chloride concentrations in the springs range from 64 to 19,000 mg/L and View the MathML source values range from +0.2‰ to +1.9‰ (average=+1.0±0.4‰), with no systematic variation along or across the arc, nor correlations with their presumed underlying basement lithologies. Additionally, nine geochemically well-characterized lavas from across the Mt. St. Helens/Mt. Adams region of the Cascade Range (Leeman et al., 2004 and Leeman et al., 2005) were analyzed for their halogen concentrations and Cl isotope compositions. In the arc lavas, Cl and Br concentrations from the volcanic front are higher than in lavas from the forearc and backarc. F and I concentrations progressively decrease from forearc to backarc, similar to the trend documented for B in most arcs. View the MathML source values of the lavas range from −0.1 to +0.8‰ (average = +0.4±0.3‰). Our results suggest that the predominantly positive View the MathML source values observed in the springs are consistent with water interaction with underlying 37Cl-enriched basalt and/or altered oceanic crust, thereby making thermal spring waters a reasonable proxy for the Cl isotope compositions of associated volcanic rocks in the Cascades. However, waters with View the MathML source values >+1.0‰ also suggest additional contributions of chlorine degassed from cooling magmas due to subsurface vapor–liquid HCl fractionation in which Cl is lost to the aqueous fluid phase and 37Cl is concentrated in the ascending magmatic HCl vapor. Future work is necessary to better constrain Cl isotope behavior during volcanic degassing and fluid–rock interaction in order to improve volatile flux estimates through subduction zones.

Isotope source apportionment of carbonaceous aerosol as a function of particle size and thermal refractiveness

NASA Astrophysics Data System (ADS)

Masalaite, Agne; Holzinger, Rupert; Remeikis, Vidmantas; Röckmann, Thomas; Dusek, Ulrike

2016-04-01

The stable carbon isotopes can be used to get information about sources and processing of carbonaceous aerosol. We will present results from source apportionment of carbonaceous aerosol as a function of particle size thermal refractiveness. Separate source apportionment for particles smaller than 200 nm and for different carbon volatility classes are rarely reported and give new insights into aerosol sources in the urban environment. Stable carbon isotope ratios were measured for the organic carbon (OC) fraction and total carbon (TC) of MOUDI impactor samples that were collected on a coastal site (Lithuania) during the winter 2012 and in the city of Vilnius (Lithuania) during the winter of 2009. The 11 impactor stages spanned a size range from 0.056 to 18 μm, but only the 6 stages in the submicron range were analysed. The δ13C values of bulk total carbon (δ13CTC) were determined with an elemental analyser (Flash EA 1112) coupled with an isotope ratio mass spectrometer (Thermo Finnigan Delta Plus Advantage) (EA - IRMS). Meanwhile δ13COC was measured using thermal-desorption isotope ratio mass spectrometry (IRMS) system. This allows a rough separation of the more volatile OC fraction (desorbed in the oven of IRMS up to 250 0C) from the more refractory fraction (desorbed up to 400 0C). In this study we investigated the composition of organic aerosol desorbed from filter samples at different temperatures using the thermal-desorption proton-transfer-reaction mass spectrometry (TD-PTR-MS) technique. During winter-time in Lithuania we expect photochemistry and biogenic emissions to be of minor importance. The main sources of aerosol carbon should be fossil fuel and biomass combustion. In both sites, the coastal and the urban site, δ13C measurements give a clear indication that the source contributions differ for small and large particles. Small particles < 200 nm are depleted in 13C with respect to larger particles by 1 - 2 ‰Ṫhis shows that OC in small particle arises mainly from fossil fuel sources, whereas OC in larger particles from 200 nm to 1 μm has higher contribution from biomass burning/other sources. Moreover, there is a clear distinction in source contribution between the more volatile OC fraction and the more refractory fraction. The more refractory fraction is enriched in 13C by 1 to 2 ‰ for both small and large particles. These results show that the fossil fuel combustion is associated to a larger degree with more volatile carbon, whereas biomass burning is the main source of the more refractory particles. According to our source apportionment, the more volatile carbon fraction in the smallest particles is almost completely from fossil fuels, whereas the more refractory carbon fraction in the large size range is almost complete from biomass burning. The more refractory small particles and the less refractory large particles are roughly an even mix of these two sources. The detailed chemical speciation of the carbonaceous aerosol will be presented as well. Acknowledgements This study was funded by the Dutch Science Foundation (NWO grants Nr. 820.01.001, and 834.08.002).

Laser vibration sensing at Fraunhofer IOSB: review and applications

NASA Astrophysics Data System (ADS)

Lutzmann, Peter; Göhler, Benjamin; Hill, Chris A.; van Putten, Frank

2017-03-01

Laser vibrometry based on coherent detection allows noncontact measurements of small-amplitude vibration characteristics of objects. This technique, commonly using the Doppler effect, offers high potential for short-range civil applications and for medium- or long-range applications in defense and security. Most commercially available laser Doppler vibrometers are for short ranges (up to a few tens of meters) and use a single beam from a low-power HeNe laser source (λ=633 nm). Medium- or long-range applications need higher laser output power, and thus, appropriate vibrometers typically operate at 1.5, 2, or 10.6 μm to meet the laser safety regulations. Spatially resolved vibrational information can be obtained from an object by using scanning laser vibrometers. To reduce measuring time and to measure transient object movements and vibrational mode structures of objects, several approaches to multibeam laser Doppler vibrometry have been developed, and some of them are already commercially available for short ranges. We focus on applications in the field of defense and security, such as target classification and identification, including camouflaged or partly concealed targets, and the detection of buried land mines. Examples of civil medium-range applications are also given.

Submillimeter-Wave Phasor Beam-Pattern Measurement Based on Two-Stage Heterodyne Mixing With Unitary Harmonic Difference

NASA Astrophysics Data System (ADS)

Hwang, Yuh-Jing; Rao, Ramprasad; Christensen, Rob; Chen, Ming-Tang; Chu, Tah-Hsiung

2007-06-01

A near-field phasor beam measurement system is developed for the characterization of heterodyne receiver optics at submillimeter-wave frequencies. The system synthesizes a pair of submillimeter-wave signals as the RF and local oscillator (LO) sources from common reference sources. The synthesized harmonic numbers of the RF and LO sources are arranged with difference by one, which makes this a new configuration with a unitary harmonic difference. The coherent RF and LO signal are down-converted by the receiver under test, then mixed with the microwave-frequency common reference signal to generate the second-order IF signal around 100 MHz for amplitude and phase comparison. The amplitude and phase fluctuation of the measurement system at 683 GHz is within +-0.2 dB and +-4deg in a 1-h period, respectively. The system dynamic range at 683 and 250 GHz can be as high as 43 and 47 dB, respectively. The system is then used to measure the receiver beam patterns at 683 and 250 GHz with different RF transmitting probe antennas.

Atmospheric bromoform at Cape Point, South Africa: an initial fixed-point data set on the African continent

NASA Astrophysics Data System (ADS)

Kuyper, Brett; Palmer, Carl J.; Labuschagne, Casper; Reason, Chris J. C.

2018-04-01

Bromoform mixing ratios in marine air were measured at Cape Point Global Atmospheric Watch Station, South Africa. This represents the first such bromoform data set recorded at this location. Manual daily measurements were made during a month-long field campaign (austral spring 2011) using a gas chromatograph-electron capture detector (GC-ECD) with a custom-built front end thermal desorption trap. The measured concentrations ranged between 4.4 and 64.6 (± 22.2 %) ppt with a mean of 24.8 ± 14.8 ppt. The highest mixing ratios recorded here occurred at, or shortly after, low tide. The diurnal cycle exhibited a morning and evening maximum with lower concentrations throughout the rest of the day. Initial analysis of the data presented indicates that the local kelp beds were the dominant source of the bromoform reported. A concentration-weighted trajectory analysis of the bromoform measurements suggests that two offshore source areas may exist. These source areas appear to be centred on the Agulhas retroflection and extend from St Helena Bay to the southwest.

Characterization of polarimetric and total intensity behaviour of a complete sample of PACO radio sources in the radio bands

NASA Astrophysics Data System (ADS)

Galluzzi, V.; Massardi, M.; Bonaldi, A.; Casasola, V.; Gregorini, L.; Trombetti, T.; Burigana, C.; Bonato, M.; De Zotti, G.; Ricci, R.; Stevens, J.; Ekers, R. D.; Bonavera, L.; di Serego Alighieri, S.; Liuzzo, E.; López-Caniego, M.; Paladino, R.; Toffolatti, L.; Tucci, M.; Callingham, J. R.

2018-03-01

We present high sensitivity (σP ≃ 0.6 mJy) polarimetric observations in seven bands, from 2.1 to 38 GHz, of a complete sample of 104 compact extragalactic radio sources brighter than 200 mJy at 20 GHz. Polarization measurements in six bands, in the range 5.5-38 GHz, for 53 of these objects were reported by Galluzzi et al. We have added new measurements in the same six bands for another 51 sources and measurements at 2.1 GHz for the full sample of 104 sources. Also, the previous measurements at 18, 24, 33, and 38 GHz were re-calibrated using the updated model for the flux density absolute calibrator, PKS1934-638, not available for the earlier analysis. The observations, carried out with the Australia Telescope Compact Array, achieved a 90 per cent detection rate (at 5σ) in polarization. 89 of our sources have a counterpart in the 72-231 MHz GLEAM (GaLactic and Extragalactic All-sky Murchison Widefield Array) survey, providing an unparalleled spectral coverage of 2.7 decades of frequency for these sources. While the total intensity data from 5.5 to 38 GHz could be interpreted in terms of single component emission, a joint analysis of more extended total intensity spectra presented here, and of the polarization spectra, reveals that over 90 per cent of our sources show clear indications of at least two emission components. We interpret this as an evidence of recurrent activity. Our high sensitivity polarimetry has allowed a 5σ detection of the weak circular polarization for ˜ 38 per cent of the data set, and a deeper estimate of 20 GHz polarization source counts than has been possible so far.

Correlating ion energies and CF{sub 2} surface production during fluorocarbon plasma processing of silicon

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

Martin, Ina T.; Zhou Jie; Fisher, Ellen R.

2006-07-01

Ion energy distribution (IED) measurements are reported for ions in the plasma molecular beam source of the imaging of radicals interacting with surfaces (IRIS) apparatus. The IEDs and relative intensities of nascent ions in C{sub 3}F{sub 8} and C{sub 4}F{sub 8} plasma molecular beams were measured using a Hiden PSM003 mass spectrometer mounted on the IRIS main chamber. The IEDs are complex and multimodal, with mean ion energies ranging from 29 to 92 eV. Integrated IEDs provided relative ion intensities as a function of applied rf power and source pressure. Generally, higher applied rf powers and lower source pressures resultedmore » in increased ion intensities and mean ion energies. Most significantly, a comparison to CF{sub 2} surface interaction measurements previously made in our laboratories reveals that mean ion energies are directly and linearly correlated to CF{sub 2} surface production in these systems.« less

Low energy recoil detection with a spherical proportional counter

NASA Astrophysics Data System (ADS)

Savvidis, I.; Katsioulas, I.; Eleftheriadis, C.; Giomataris, I.; Papaevangellou, T.

2018-01-01

We present results for the detection of low energy nuclear recoils in the keV energy region, from measurements performed with the Spherical Proportional Counter (SPC). An 241Am-9Be fast neutron source is used in order to obtain neutron-nucleus elastic scattering events inside the gaseous volume of the detector. The detector performance in the keV energy region was measured by observing the 5.9 keV line of a 55Fe X-ray source, with energy resolution of 10% (σ). The toolkit GEANT4 was used to simulate the irradiation of the detector by an 241Am-9Be source, while SRIM was used to calculate the Ionization Quenching Factor (IQF), the simulation results are compared with the measurements. The potential of the SPC in low energy recoil detection makes the detector a good candidate for a wide range of applications, including Supernova or reactor neutrino detection and Dark Matter (WIMP) searches (via coherent elastic scattering).

An analytic technique for statistically modeling random atomic clock errors in estimation

NASA Technical Reports Server (NTRS)

Fell, P. J.

1981-01-01

Minimum variance estimation requires that the statistics of random observation errors be modeled properly. If measurements are derived through the use of atomic frequency standards, then one source of error affecting the observable is random fluctuation in frequency. This is the case, for example, with range and integrated Doppler measurements from satellites of the Global Positioning and baseline determination for geodynamic applications. An analytic method is presented which approximates the statistics of this random process. The procedure starts with a model of the Allan variance for a particular oscillator and develops the statistics of range and integrated Doppler measurements. A series of five first order Markov processes is used to approximate the power spectral density obtained from the Allan variance.

Improved laser-based triangulation sensor with enhanced range and resolution through adaptive optics-based active beam control.

PubMed

Reza, Syed Azer; Khwaja, Tariq Shamim; Mazhar, Mohsin Ali; Niazi, Haris Khan; Nawab, Rahma

2017-07-20

Various existing target ranging techniques are limited in terms of the dynamic range of operation and measurement resolution. These limitations arise as a result of a particular measurement methodology, the finite processing capability of the hardware components deployed within the sensor module, and the medium through which the target is viewed. Generally, improving the sensor range adversely affects its resolution and vice versa. Often, a distance sensor is designed for an optimal range/resolution setting depending on its intended application. Optical triangulation is broadly classified as a spatial-signal-processing-based ranging technique and measures target distance from the location of the reflected spot on a position sensitive detector (PSD). In most triangulation sensors that use lasers as a light source, beam divergence-which severely affects sensor measurement range-is often ignored in calculations. In this paper, we first discuss in detail the limitations to ranging imposed by beam divergence, which, in effect, sets the sensor dynamic range. Next, we show how the resolution of laser-based triangulation sensors is limited by the interpixel pitch of a finite-sized PSD. In this paper, through the use of tunable focus lenses (TFLs), we propose a novel design of a triangulation-based optical rangefinder that improves both the sensor resolution and its dynamic range through adaptive electronic control of beam propagation parameters. We present the theory and operation of the proposed sensor and clearly demonstrate a range and resolution improvement with the use of TFLs. Experimental results in support of our claims are shown to be in strong agreement with theory.

Inverse modelling-based reconstruction of the Chernobyl source term available for long-range transport

NASA Astrophysics Data System (ADS)

Davoine, X.; Bocquet, M.

2007-03-01

The reconstruction of the Chernobyl accident source term has been previously carried out using core inventories, but also back and forth confrontations between model simulations and activity concentration or deposited activity measurements. The approach presented in this paper is based on inverse modelling techniques. It relies both on the activity concentration measurements and on the adjoint of a chemistry-transport model. The location of the release is assumed to be known, and one is looking for a source term available for long-range transport that depends both on time and altitude. The method relies on the maximum entropy on the mean principle and exploits source positivity. The inversion results are mainly sensitive to two tuning parameters, a mass scale and the scale of the prior errors in the inversion. To overcome this hardship, we resort to the statistical L-curve method to estimate balanced values for these two parameters. Once this is done, many of the retrieved features of the source are robust within a reasonable range of parameter values. Our results favour the acknowledged three-step scenario, with a strong initial release (26 to 27 April), followed by a weak emission period of four days (28 April-1 May) and again a release, longer but less intense than the initial one (2 May-6 May). The retrieved quantities of iodine-131, caesium-134 and caesium-137 that have been released are in good agreement with the latest reported estimations. Yet, a stronger apportionment of the total released activity is ascribed to the first period and less to the third one. Finer chronological details are obtained, such as a sequence of eruptive episodes in the first two days, likely related to the modulation of the boundary layer diurnal cycle. In addition, the first two-day release surges are found to have effectively reached an altitude up to the top of the domain (5000 m).

Range imaging laser radar

DOEpatents

Scott, Marion W.

1990-01-01

A laser source is operated continuously and modulated periodically (typicy sinusoidally). A receiver imposes another periodic modulation on the received optical signal, the modulated signal being detected by an array of detectors of the integrating type. Range to the target determined by measuring the phase shift of the intensity modulation on the received optical beam relative to a reference. The receiver comprises a photoemitter for converting the reflected, periodically modulated, return beam to an accordingly modulated electron stream. The electron stream is modulated by a local demodulation signal source and subsequently converted back to a photon stream by a detector. A charge coupled device (CCD) array then averages and samples the photon stream to provide an electrical signal in accordance with the photon stream.

Range imaging laser radar

DOEpatents

Scott, M.W.

1990-06-19

A laser source is operated continuously and modulated periodically (typically sinusoidally). A receiver imposes another periodic modulation on the received optical signal, the modulated signal being detected by an array of detectors of the integrating type. Range to the target determined by measuring the phase shift of the intensity modulation on the received optical beam relative to a reference. The receiver comprises a photoemitter for converting the reflected, periodically modulated, return beam to an accordingly modulated electron stream. The electron stream is modulated by a local demodulation signal source and subsequently converted back to a photon stream by a detector. A charge coupled device (CCD) array then averages and samples the photon stream to provide an electrical signal in accordance with the photon stream. 2 figs.

The impact of agricultural soil erosion on the global carbon cycle

USGS Publications Warehouse

Van Oost, Kristof; Quine, T.A.; Govers, G.; De Gryze, S.; Six, J.; Harden, J.W.; Ritchie, J.C.; McCarty, G.W.; Heckrath, G.; Kosmas, C.; Giraldez, J.V.; Marques Da Silva, J.R.; Merckx, R.

2007-01-01

Agricultural soil erosion is thought to perturb the global carbon cycle, but estimates of its effect range from a source of 1 petagram per year -1 to a sink of the same magnitude. By using caesium-137 and carbon inventory measurements from a large-scale survey, we found consistent evidence for an erosion-induced sink of atmospheric carbon equivalent to approximately 26% of the carbon transported by erosion. Based on this relationship, we estimated a global carbon sink of 0.12 (range 0.06 to 0.27) petagrams of carbon per year-1 resulting from erosion in the world's agricultural landscapes. Our analysis directly challenges the view that agricultural erosion represents an important source or sink for atmospheric CO2.

Assessing the capacity of social determinants of health data to augment predictive models identifying patients in need of wraparound social services.

PubMed

Kasthurirathne, Suranga N; Vest, Joshua R; Menachemi, Nir; Halverson, Paul K; Grannis, Shaun J

2018-01-01

A growing variety of diverse data sources is emerging to better inform health care delivery and health outcomes. We sought to evaluate the capacity for clinical, socioeconomic, and public health data sources to predict the need for various social service referrals among patients at a safety-net hospital. We integrated patient clinical data and community-level data representing patients' social determinants of health (SDH) obtained from multiple sources to build random forest decision models to predict the need for any, mental health, dietitian, social work, or other SDH service referrals. To assess the impact of SDH on improving performance, we built separate decision models using clinical and SDH determinants and clinical data only. Decision models predicting the need for any, mental health, and dietitian referrals yielded sensitivity, specificity, and accuracy measures ranging between 60% and 75%. Specificity and accuracy scores for social work and other SDH services ranged between 67% and 77%, while sensitivity scores were between 50% and 63%. Area under the receiver operating characteristic curve values for the decision models ranged between 70% and 78%. Models for predicting the need for any services reported positive predictive values between 65% and 73%. Positive predictive values for predicting individual outcomes were below 40%. The need for various social service referrals can be predicted with considerable accuracy using a wide range of readily available clinical and community data that measure socioeconomic and public health conditions. While the use of SDH did not result in significant performance improvements, our approach represents a novel and important application of risk predictive modeling. © The Author 2017. Published by Oxford University Press on behalf of the American Medical Informatics Association. All rights reserved. For Permissions, please email: journals.permissions@oup.com

Global comparison of VOC and CO observations in urban areas

NASA Astrophysics Data System (ADS)

von Schneidemesser, Erika; Monks, Paul S.; Plass-Duelmer, Christian

2010-12-01

Speciated volatile organic compound (VOC) and carbon monoxide (CO) measurements from the Marylebone Road site in central London from 1998 through 2008 are presented. Long-term trends show statistically significant decreases for all the VOCs considered, ranging from -3% to -26% per year. Carbon monoxide decreased by -12% per year over the measurement period. The VOC trends observed at the kerbside site in London showed greater rates of decline relative to trends from monitoring sites in rural England (Harwell) and a remote high-altitude site (Hohenpeissenberg), which showed decreases for individual VOCs from -2% to -13% per year. Over the same 1998 through 2008 period VOC to CO ratios for London remained steady, an indication that emissions reduction measures affected the measured compounds equally. Relative trends comparing VOC to CO ratios between Marylebone Road and Hohenpeissenberg showed greater similarities than absolute trends, indicating that emissions reductions measures in urban areas are reflected by regional background locations. A comparison of VOC mixing ratios and VOC to CO ratios was undertaken for London and other global cities. Carbon monoxide and VOCs (alkanes greater than C 5, alkenes, and aromatics) were found to be strongly correlated (>0.8) in the Annex I countries, whereas only ethene and ethyne were strongly correlated with CO in the non-Annex I countries. The correlation results indicate significant emissions from traffic-related sources in Annex I countries, and a much larger influence of other sources, such as industry and LPG-related sources in non-Annex I countries. Yearly benzene to ethyne ratios for London from 2000 to 2008 ranged from 0.17 to 0.29 and compared well with previous results from US cities and three global megacities.

New UV-source catalogs, UV spectral database, UV variables and science tools from the GALEX surveys

NASA Astrophysics Data System (ADS)

Bianchi, Luciana; de la Vega, Alexander; Shiao, Bernard; Bohlin, Ralph

2018-03-01

We present a new, expanded and improved catalog of Ultraviolet (UV) sources from the GALEX All-Sky Imaging survey: GUVcat_AIS (Bianchi et al. in Astrophys. J. Suppl. Ser. 230:24, 2017). The catalog includes 83 million unique sources (duplicate measurements and rim artifacts are removed) measured in far-UV and near-UV. With respect to previous versions (Bianchi et al. in Mon. Not. R. Astron. Soc. 411:2770 2011a, Adv. Space Res. 53:900-991, 2014), GUVcat_AIS covers a slightly larger area, 24,790 square degrees, and includes critical corrections and improvements, as well as new tags, in particular to identify sources in the footprint of extended objects, where pipeline source detection may fail and custom-photometry may be necessary. The UV unique-source catalog facilitates studies of density of sources, and matching of the UV samples with databases at other wavelengths. We also present first results from two ongoing projects, addressing respectively UV variability searches on time scales from seconds to years by mining the GALEX photon archive, and the construction of a database of ˜120,000 GALEX UV spectra (range ˜1300-3000 Å), including quality and calibration assessment and classification of the grism, hence serendipitous, spectral sources.

Methodology and Software for Gross Defect Detection of Spent Nuclear Fuel at the Atucha-I Reactor

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

Sitaraman, Shivakumar; Ham, Young S.; Gharibyan, Narek

At the Atucha-I pressurized heavy water reactor in Argentina, fuel assemblies in the spent fuel pools are stored by suspending them in two vertically stacked layers. This introduces the unique problem of verifying the presence of fuel in either layer without physically moving the fuel assemblies. Since much of the fuel is very old, Cerenkov viewing devices are often not very useful even for the top layer. Given that the facility uses both natural uranium and slightly enriched uranium at 0.85 w% {sup 235}U, and has been in operation since 1974, a wide range of burnups and cooling times canmore » exist in any given pool. A spent fuel neutron counting tool consisting of a fission chamber, SFNC, has been used at the site to verify the presence of fuel up to burnups of 8000 MWd/t. At higher discharge burnups to levels up 11,000 MWd/t, the existing signal processing software of the tool was found to fail due to non-linearity of the source term with burnup. A new Graphical User Interface software package based on the LabVIEW platform was developed to predict expected neutron signals covering all ranges of burnups and cooling times and establish maps of expected signals at various pool locations. The algorithm employed in the software uses a set of transfer functions in a 47-energy group structure which are coupled with a 47-energy group neutron source spectrum based on various cooling times and burnups for each of the two enrichment levels. The database of the software consists of these transfer functions for the three different inter-assembly pitches that the fuel is stored in at the site. The transfer functions were developed for a 6 by 6 matrix of fuel assemblies with the detector placed at the center surrounded by four near neighbors, eight next nearest neighbors and so on for the 36 assemblies. These calculations were performed using Monte Carlo radiation transport methods. The basic methodology consisted of starting sources in each of the assemblies and tallying the contribution to the detector by a single neutron in each of the 47 energy groups used. Thus for the single existing symmetric pitch in the pools, where the vertical and horizontal separations are equal, only 6 sets of transfer functions are required. For the two asymmetrical pitches, nine sets of transfer functions are stored. In addition, source spectra at burnups ranging from 4000 to 20000 MWd/t and cooling times up to 40 years are stored. These source terms were established based on CANDU 37-rod fuel that is very similar to the Atucha fuel. Linear interpolation is used by the software for both burnup and cooling time to establish source terms at any intermediate condition. Using the burnup, cooling time and initial enrichment of the surrounding assemblies a set of source strengths in the 47-group structure for each of the 36 assemblies is established and multiplied group-wise with the appropriate transfer function set. The grand total over the 47 groups for all 36 assemblies is the predicted signal at the detector. The software was initially calibrated against a set of typically 5-6 measurements chosen from among the measured data at each level of the six pools and calibration factors were established. The set used for calibration is chosen such that it is fairly representative of the range of spent fuel assembly characteristics present in each level. Once established, these calibration factors can be repeatedly used for verification purposes. Recalibration will be required if the hardware or pool configurations has changed. It will also be required if a long enough time has elapsed since they were established thus making a cooling time correction necessary. The objective of the inspection is to detect missing fuel from one or more nearest neighbors of the detector. During the verification mode of the software, the predicted and measured signals are compared and the inspector is alerted if the difference between the two signals is beyond a set tolerance limit. Based on the uncertainties associated with both the calculations and measurements, a lower limit of the tolerance will be 15% with an upper limit of 20%. For the most part a 20% tolerance limit will be able to detect a missing assembly since in the vast majority of cases the drop in signal due to a single missing nearest neighbor assembly will be in the range 24-27%. The software was benchmarked against an extensive set of measured data taken at the site in 2004. Overall, 326 data points were examined and the prediction of the calibrated software was compared to the measurements within a set tolerance of ±20%. Of these, 283 of the predicted signals representing 87% of the total matched the measured data within ±10%. A further 27 or 8% were in the range of ±10-15% and 8 or 2.5% were in the range of ±15-20%. Thus, 97.5% of the data matched the measurements within the set tolerance limit of 20%, with 95% matching measured data with the lowest allowed tolerance limit of ±15%. The remaining 2.5% had measured signals that were very different from those at locations with very similar surrounding assemblies and the cause of these discrepancies could not be ascertained from the measurement logs. In summary, 97.5% of the predictions matched the measurements within the set 20% tolerance limit providing proof of the robustness of the software. This software package linked to SFNC will be deployed at the site and will enhance the capability of gross defect verification for the whole range of burnup, cooling time and initial enrichments of the spent fuel being discharged into the various pools at the Atucha-I reactor site.« less

Estimated Reduction in Cancer Risk due to PAH Exposures If Source Control Measures during the 2008 Beijing Olympics Were Sustained

PubMed Central

Jia, Yuling; Stone, Dave; Wang, Wentao; Schrlau, Jill; Tao, Shu; Massey Simonich, Staci L.

2011-01-01

Background The 2008 Beijing Olympic Games provided a unique case study to investigate the effect of source control measures on the reduction in air pollution, and associated inhalation cancer risk, in a Chinese megacity. Objectives We measured 17 carcinogenic polycyclic aromatic hydrocarbons (PAHs) and estimated the lifetime excess inhalation cancer risk during different periods of the Beijing Olympic Games, to assess the effectiveness of source control measures in reducing PAH-induced inhalation cancer risks. Methods PAH concentrations were measured in samples of particulate matter ≤ 2.5 μm in aerodynamic diameter (PM2.5) collected during the Beijing Olympic Games, and the associated inhalation cancer risks were estimated using a point-estimate approach based on relative potency factors. Results We estimated the number of lifetime excess cancer cases due to exposure to the 17 carcinogenic PAHs [12 priority pollutant PAHs and five high-molecular-weight (302 Da) PAHs (MW 302 PAHs)] to range from 6.5 to 518 per million people for the source control period concentrations and from 12.2 to 964 per million people for the nonsource control period concentrations. This would correspond to a 46% reduction in estimated inhalation cancer risk due to source control measures, if these measures were sustained over time. Benzo[b]fluoranthene, dibenz[a,h]anthracene, benzo[a]pyrene, and dibenzo[a,l]pyrene were the most carcinogenic PAH species evaluated. Total excess inhalation cancer risk would be underestimated by 23% if we did not include the five MW 302 PAHs in the risk calculation. Conclusions Source control measures, such as those imposed during the 2008 Beijing Olympics, can significantly reduce the inhalation cancer risk associated with PAH exposure in Chinese megacities similar to Beijing. MW 302 PAHs are a significant contributor to the estimated overall inhalation cancer risk. PMID:21632310

Modelling of deposited black carbon with the Lagrangian particle dispersion model FLEXPART in backward mode

NASA Astrophysics Data System (ADS)

Eckhardt, Sabine; Cassiani, Massimo; Sollum, Espen; Evangeliou, Nikolaos; Stohl, Andreas

2017-04-01

Lagrangian particle dispersion models are popular tools to simulate the dispersion of trace gases, aerosols or radionuclides in the atmosphere. If they consider only linear processes, they are self-adjoint, i.e., they can be run forward and backward in time without changes to the source code. Backward simulations are very efficient if the number of receptors is smaller than the number of sources, and they are well suited to establish source-receptor (s-r) relationships for measurements of various trace substances in air. However, not only the air concentrations are of interest, but also the s-r relationships for deposition are important for interpreting measurement data. E.g., deposition of dust is measured regularly in ice cores, partly also as a proxy to understand changes in aridity in dust source regions. Contamination of snow by black carbon (BC) aerosols has recently become a hot topic because of the potential impact of BC on the snow albedo. To interpret such deposition measurements and study the sources of the deposited substance, it would be convenient to have a model that is capable of efficient s-r relationship calculations for such types of measurements. We present here the implementation of such an algorithm into the Lagrangian particle dispersion model FLEXPART, and test the new scheme by comparisons with results from forward simulations as well as comparisons with measurements. As an application, we analyse source regions for elemental carbon (EC) measured in snow over the years 2014-2016 in the Russian Arctic. Simulations using an annual constant black carbon inventory based on ECLIPSE V5 and GFED (Global Fire Emission Database), have been performed. The meteorological data used in the simulation are 3 hourly operational data from the European Centre of Medium Range Weather Forecast (ECMWF) on a 1 degree grid resolution and 138 vertical levels. The model is able to capture very well the measured concentrations. Gas flaring and residential/commercial combustion can be identified as the most important sources. High concentrations measured near the Ob River (up to 170 ng g-1) can be associated with air masses coming from Europe.

Development of a High Dynamic Range Pixel Array Detector for Synchrotrons and XFELs

NASA Astrophysics Data System (ADS)

Weiss, Joel Todd

Advances in synchrotron radiation light source technology have opened new lines of inquiry in material science, biology, and everything in between. However, x-ray detector capabilities must advance in concert with light source technology to fully realize experimental possibilities. X-ray free electron lasers (XFELs) place particularly large demands on the capabilities of detectors, and developments towards diffraction-limited storage ring sources also necessitate detectors capable of measuring very high flux [1-3]. The detector described herein builds on the Mixed Mode Pixel Array Detector (MM-PAD) framework, developed previously by our group to perform high dynamic range imaging, and the Adaptive Gain Integrating Pixel Detector (AGIPD) developed for the European XFEL by a collaboration between Deustsches Elektronen-Synchrotron (DESY), the Paul-Scherrer-Institute (PSI), the University of Hamburg, and the University of Bonn, led by Heinz Graafsma [4, 5]. The feasibility of combining adaptive gain with charge removal techniques to increase dynamic range in XFEL experiments is assessed by simulating XFEL scatter with a pulsed infrared laser. The strategy is incorporated into pixel prototypes which are evaluated with direct current injection to simulate very high incident x-ray flux. A fully functional 16x16 pixel hybrid integrating x-ray detector featuring several different pixel architectures based on the prototypes was developed. This dissertation describes its operation and characterization. To extend dynamic range, charge is removed from the integration node of the front-end amplifier without interrupting integration. The number of times this process occurs is recorded by a digital counter in the pixel. The parameter limiting full well is thereby shifted from the size of an integration capacitor to the depth of a digital counter. The result is similar to that achieved by counting pixel array detectors, but the integrators presented here are designed to tolerate a sustained flux >1011 x-rays/pixel/second. In addition, digitization of residual analog signals allows sensitivity for single x-rays or low flux signals. Pixel high flux linearity is evaluated by direct exposure to an unattenuated synchrotron source x-ray beam and flux measurements of more than 1010 9.52 keV x-rays/pixel/s are made. Detector sensitivity to small signals is evaluated and dominant sources of error are identified. These new pixels boast multiple orders of magnitude improvement in maximum sustained flux over the MM-PAD, which is capable of measuring a sustained flux in excess of 108 x-rays/pixel/second while maintaining sensitivity to smaller signals, down to single x-rays.

In vitro glucose measurement using tunable mid-infrared laser spectroscopy combined with fiber-optic sensor

PubMed Central

Yu, Songlin; Li, Dachao; Chong, Hao; Sun, Changyue; Yu, Haixia; Xu, Kexin

2013-01-01

Because mid-infrared (mid-IR) spectroscopy is not a promising method to noninvasively measure glucose in vivo, a method for minimally invasive high-precision glucose determination in vivo by mid-IR laser spectroscopy combined with a tunable laser source and small fiber-optic attenuated total reflection (ATR) sensor is introduced. The potential of this method was evaluated in vitro. This research presents a mid-infrared tunable laser with a broad emission spectrum band of 9.19 to 9.77μm(1024~1088 cm−1) and proposes a method to control and stabilize the laser emission wavelength and power. Moreover, several fiber-optic ATR sensors were fabricated and investigated to determine glucose in combination with the tunable laser source, and the effective sensing optical length of these sensors was determined for the first time. In addition, the sensitivity of this system was four times that of a Fourier transform infrared (FT-IR) spectrometer. The noise-equivalent concentration (NEC) of this laser measurement system was as low as 3.8 mg/dL, which is among the most precise glucose measurements using mid-infrared spectroscopy. Furthermore, a partial least-squares regression and Clarke error grid were used to quantify the predictability and evaluate the prediction accuracy of glucose concentration in the range of 5 to 500 mg/dL (physiologically relevant range: 30~400 mg/dL). The experimental results were clinically acceptable. The high sensitivity, tunable laser source, low NEC and small fiber-optic ATR sensor demonstrate an encouraging step in the work towards precisely monitoring glucose levels in vivo. PMID:24466493

An Auditory Illusion of Proximity of the Source Induced by Sonic Crystals

PubMed Central

Spiousas, Ignacio; Etchemendy, Pablo E.; Vergara, Ramiro O.; Calcagno, Esteban R.; Eguia, Manuel C.

2015-01-01

In this work we report an illusion of proximity of a sound source created by a sonic crystal placed between the source and a listener. This effect seems, at first, paradoxical to naïve listeners since the sonic crystal is an obstacle formed by almost densely packed cylindrical scatterers. Even when the singular acoustical properties of these periodic composite materials have been studied extensively (including band gaps, deaf bands, negative refraction, and birrefringence), the possible perceptual effects remain unexplored. The illusion reported here is studied through acoustical measurements and a psychophysical experiment. The results of the acoustical measurements showed that, for a certain frequency range and region in space where the focusing phenomenon takes place, the sonic crystal induces substantial increases in binaural intensity, direct-to-reverberant energy ratio and interaural cross-correlation values, all cues involved in the auditory perception of distance. Consistently, the results of the psychophysical experiment revealed that the presence of the sonic crystal between the sound source and the listener produces a significant reduction of the perceived relative distance to the sound source. PMID:26222281

An Auditory Illusion of Proximity of the Source Induced by Sonic Crystals.

PubMed

Spiousas, Ignacio; Etchemendy, Pablo E; Vergara, Ramiro O; Calcagno, Esteban R; Eguia, Manuel C

2015-01-01

In this work we report an illusion of proximity of a sound source created by a sonic crystal placed between the source and a listener. This effect seems, at first, paradoxical to naïve listeners since the sonic crystal is an obstacle formed by almost densely packed cylindrical scatterers. Even when the singular acoustical properties of these periodic composite materials have been studied extensively (including band gaps, deaf bands, negative refraction, and birrefringence), the possible perceptual effects remain unexplored. The illusion reported here is studied through acoustical measurements and a psychophysical experiment. The results of the acoustical measurements showed that, for a certain frequency range and region in space where the focusing phenomenon takes place, the sonic crystal induces substantial increases in binaural intensity, direct-to-reverberant energy ratio and interaural cross-correlation values, all cues involved in the auditory perception of distance. Consistently, the results of the psychophysical experiment revealed that the presence of the sonic crystal between the sound source and the listener produces a significant reduction of the perceived relative distance to the sound source.

Structure-specific scalar intensity measures for near-source and ordinary earthquake ground motions

USGS Publications Warehouse

Luco, N.; Cornell, C.A.

2007-01-01

Introduced in this paper are several alternative ground-motion intensity measures (IMs) that are intended for use in assessing the seismic performance of a structure at a site susceptible to near-source and/or ordinary ground motions. A comparison of such IMs is facilitated by defining the "efficiency" and "sufficiency" of an IM, both of which are criteria necessary for ensuring the accuracy of the structural performance assessment. The efficiency and sufficiency of each alternative IM, which are quantified via (i) nonlinear dynamic analyses of the structure under a suite of earthquake records and (ii) linear regression analysis, are demonstrated for the drift response of three different moderate- to long-period buildings subjected to suites of ordinary and of near-source earthquake records. One of the alternative IMs in particular is found to be relatively efficient and sufficient for the range of buildings considered and for both the near-source and ordinary ground motions. ?? 2007, Earthquake Engineering Research Institute.

Abatement of Perfluorinated Compounds Using Cylindrical Microwave Plasma Source at Low Pressure

NASA Astrophysics Data System (ADS)

Kim, Seong Bong; Park, S.; Park, Y.; Youn, S.; Yoo, S. J.

2016-10-01

Microwave plasma source with a cylindrical cavity has been proposed to abate the perfluorinated compounds (PFCs). This plasma source was designed to generate microwave plasma with the cylindrical shape and to be easily installed in existing exhaust line. The microwave frequency is 2.45 GHz and the operating pressure range is 0.1 Torr to 0.3 Torr. The plasma characteristic of the cylindrical microwave plasma source was measured using the optical spectrometer, and tunable diode laser absorption spectroscopy (TDLAS). The destruction and removal efficiency (DRE) of CF4 and CHF3 were measured by a quadrupole mass spectroscopy (QMS) with the various operation conditions. The effect of the addition of the oxygen gas were tested and also the correlation between the plasma parameters and the DRE are presented in this study. This work was supported by R&D Program of ``Plasma Advanced Technology for Agriculture and Food (Plasma Farming)'' through the National Fusion Research Institute of Korea (NFRI) funded by the Government funds.

Interplanetary baseline observations of type III solar radio bursts

NASA Technical Reports Server (NTRS)

Weber, R. R.; Fitzenreiter, R. J.; Novaco, J. C.; Fainberg, J.

1977-01-01

Simultaneous observations of type III radio bursts from spacecraft separated by 0.43 AU have been made using the solar orbiters Helios-A and Helios-B. The burst beginning at 19:22 UT on March 28, 1976, has been located from the intersection of the source directions measured at each spacecraft and from burst arrival-time differences. The source positions range from 0.03 AU from the sun at 3000 kHz to 0.08 AU at 585 kHz. The electron density along the burst trajectory and the exciter velocity (0.13c) were determined directly without the need to assume a density model, as has been done with single-spacecraft observations. The separation of Helios-A and -B has also provided measurements of burst directivity at low frequencies. For the March 28 burst the intensity observed from near the source longitude (Helios-B) was 3-10dB greater than that from 60 deg west of the source (Helios-A)

Source levels and call parameters of harbor seal breeding vocalizations near a terrestrial haulout site in Glacier Bay National Park and Preserve.

PubMed

Matthews, Leanna P; Parks, Susan E; Fournet, Michelle E H; Gabriele, Christine M; Womble, Jamie N; Klinck, Holger

2017-03-01

Source levels of harbor seal breeding vocalizations were estimated using a three-element planar hydrophone array near the Beardslee Islands in Glacier Bay National Park and Preserve, Alaska. The average source level for these calls was 144 dB RMS re 1 μPa at 1 m in the 40-500 Hz frequency band. Source level estimates ranged from 129 to 149 dB RMS re 1 μPa. Four call parameters, including minimum frequency, peak frequency, total duration, and pulse duration, were also measured. These measurements indicated that breeding vocalizations of harbor seals near the Beardslee Islands of Glacier Bay National Park are similar in duration (average total duration: 4.8 s, average pulse duration: 3.0 s) to previously reported values from other populations, but are 170-220 Hz lower in average minimum frequency (78 Hz).

High power narrow-band fiber-based ASE source.

PubMed

Schmidt, O; Rekas, M; Wirth, C; Rothhardt, J; Rhein, S; Kliner, A; Strecker, M; Schreiber, T; Limpert, J; Eberhardt, R; Tünnermann, A

2011-02-28

In this paper we describe a high power narrow-band amplified spontaneous emission (ASE) light source at 1030 nm center wavelength generated in an Yb-doped fiber-based experimental setup. By cutting a small region out of a broadband ASE spectrum using two fiber Bragg gratings a strongly constrained bandwidth of 12±2 pm (3.5±0.6 GHz) is formed. A two-stage high power fiber amplifier system is used to boost the output power up to 697 W with a measured beam quality of M2≤1.34. In an additional experiment we demonstrate a stimulated Brillouin scattering (SBS) suppression of at least 17 dB (theoretically predicted ~20 dB), which is only limited by the dynamic range of the measurement and not by the onset of SBS when using the described light source. The presented narrow-band ASE source could be of great interest for brightness scaling applications by beam combination, where SBS is known as a limiting factor.

GLAST Science Across Wavelengths

NASA Astrophysics Data System (ADS)

Blandford, R. D.

2006-12-01

The GLAST satellites is almost guaranteed to revolutionize GeV gamma ray astronomy because of the great discoveries that are being made at hard X-ray energy by the Suzaku and Swift satellites and in the TeV range using the H.E.S.S. and Magic telescopes. Unidentified EGRET sources are likely to be identified and new and fainter sources will be found. Known classes of sources blazars, pulsars, gamma ray bursts, supernova remnants, binary X-ray sources and so on will be monitored in much greater detail. Finally, there is the need to limit or even detect dark matter through its annihilation signature. The science that will emerge from GLAST will be determined in large measure by the effort that is put into multiwavelength observing. This will require significant commitments of observing time for monitoring pulsar arrival times, measuring faint galaxy spectra, detecting GeV gamma rays gamma ray bursts and so on. In this talk I will attempt to summarize current thinking on the GLAST multi-wavelength observing program and propose some new approaches.

Combining measurements and modelling to quantify the contribution of atmospheric fallout, local industry and road traffic to PAH stocks in contrasting catchments.

PubMed

Gateuille, David; Evrard, Olivier; Lefevre, Irène; Moreau-Guigon, Elodie; Alliot, Fabrice; Chevreuil, Marc; Mouchel, Jean-Marie

2014-06-01

Various sources supply PAHs that accumulate in soils. The methodology we developed provided an evaluation of the contribution of local sources (road traffic, local industries) versus remote sources (long range atmospheric transport, fallout and gaseous exchanges) to PAH stocks in two contrasting subcatchments (46-614 km²) of the Seine River basin (France). Soil samples (n = 336) were analysed to investigate the spatial pattern of soil contamination across the catchments and an original combination with radionuclide measurements provided new insights into the evolution of the contamination with depth. Relationships between PAH concentrations and the distance to the potential sources were modelled. Despite both subcatchments are mainly rural, roadside areas appeared to concentrate 20% of the contamination inside the catchment while a local industry was found to be responsible for up to 30% of the stocks. Those results have important implications for understanding and controlling PAH contamination in rural areas of early-industrialized regions. Copyright © 2014 Elsevier Ltd. All rights reserved.

A source array for generating higher order acoustic modes in circular ducts

NASA Technical Reports Server (NTRS)

Wyerman, B. R.; Reethof, G.

1976-01-01

A unique source array has been developed for the generation of both spinning and non-spinning higher order modes in a circular duct. The array consists of two concentric rings of sources. Through individual control of the response of each element, the array provided phase and amplitude control in the radial as well as circumferential directions. Radial modes shapes were measured in a 12-inch diameter anechoically-terminated hollow duct. These modes could be generated at their cut-off frequency and throughout a frequency range extending to the cut-off frequency for the next higher order radial mode. Comparisons are given between theory and experiment for the generation of specific modes. The radial dependence of the measured mode shapes was enhanced considerably by the design of this array. The results indicate a significant improvement over previous mode generation mechanisms. The contamination of the generated mode by additional spurious modes is also considered for variations between individual elements within the source array.

Application of spatially resolved high resolution crystal spectrometry to inertial confinement fusion plasmas.

PubMed

Hill, K W; Bitter, M; Delgado-Aparacio, L; Pablant, N A; Beiersdorfer, P; Schneider, M; Widmann, K; Sanchez del Rio, M; Zhang, L

2012-10-01

High resolution (λ∕Δλ ∼ 10 000) 1D imaging x-ray spectroscopy using a spherically bent crystal and a 2D hybrid pixel array detector is used world wide for Doppler measurements of ion-temperature and plasma flow-velocity profiles in magnetic confinement fusion plasmas. Meter sized plasmas are diagnosed with cm spatial resolution and 10 ms time resolution. This concept can also be used as a diagnostic of small sources, such as inertial confinement fusion plasmas and targets on x-ray light source beam lines, with spatial resolution of micrometers, as demonstrated by laboratory experiments using a 250-μm (55)Fe source, and by ray-tracing calculations. Throughput calculations agree with measurements, and predict detector counts in the range 10(-8)-10(-6) times source x-rays, depending on crystal reflectivity and spectrometer geometry. Results of the lab demonstrations, application of the technique to the National Ignition Facility (NIF), and predictions of performance on NIF will be presented.

Occurrence, sources, and ecological risks of PBDEs, PCBs, OCPs, and PAHs in surface sediments of the Yangtze River Delta city cluster, China.

PubMed

Zhang, Ting; Yang, Wen-Long; Chen, She-Jun; Shi, Dian-Long; Zhao, Hu; Ding, Yi; Huang, Ye-Ru; Li, Nan; Ren, Yue; Mai, Bi-Xian

2014-08-01

Polybrominated diphenyl ethers (PBDEs), organochlorine pesticides (OCPs), polychlorinated biphenyls (PCBs), and polycyclic aromatic hydrocarbons (PAHs) in 25 surface sediments in three cities (Nantong, Wuxi, and Suzhou) in the Yangtze River Delta, eastern China were measured. The mean concentrations were 378, 45.8, 1.98, 4,002 ng/g for PBDEs, OCPs, PCBs, and PAHs, respectively. Their levels in the sediments in the three cities were generally consistent with the city industrialization. PBDEs and OCPs were markedly dominated by deca-BDE (>90 %) and DDTs (>70 %). A principle component analysis of the analytes identified three major factors suggesting different sources of the contaminants in the sediments. PBDEs and the organic carbon in the sediments have common sources from industrial activities; whereas OCPs and PCBs, correlated with the second factor, were mainly from historical sources. The third factor with loadings of PAHs is indicative of various combustion sources. Ecological risk assessment indicated that the potential highest risk is from DDTs, for which 22 sites exceed the effects range low (ERL) values and three sites exceed the effects range median (ERM) value.

A synchrotron-radiation-based variable angle ellipsometer for the visible to vacuum ultraviolet spectral range

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

Neumann, M. D., E-mail: maciej.neumann@isas.de; Cobet, C.; Esser, N.

2014-05-15

A rotating analyzer spectroscopic polarimeter and ellipsometer with a wide-range θ-2θ goniometer installed at the Insertion Device Beamline of the Metrology Light Source in Berlin is presented. With a combination of transmission- and reflection-based polarizing elements and the inherent degree of polarization of the undulator radiation, this ellipsometer is able to cover photon energies from about 2 eV up to 40 eV. Additionally, a new compensator design based on a CaF{sub 2} Fresnel rhomb is presented. This compensator allows ellipsometric measurements with circular polarization in the vacuum ultraviolet spectral range and thus, for example, the characterization of depolarizing samples. The new instrumentmore » was initially used for the characterization of the polarization of the beamline. The technical capabilities of the ellipsometer are demonstrated by a cohesive wide-range measurement of the dielectric function of epitaxially grown ZnO.« less

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

Tyler, S.C.; Zimmerman, P.R.; Cumberbatch, C.

Ratios of C{sup 13}/C{sup 12} have been measured in methane from a variety of sources in tropical Kenya. Ranges of delta-C{sup 13} in CH{sub 4} for termites (most values range from {minus}56 to {minus}64{per thousand}, one is at {minus}44{per thousand}), one is at approximately {minus}73{per thousand}, rice paddies (range {minus}57 to {minus}63{per thousand}), and wetlands (range-45 to {minus}50{per thousand} for Lake Baringo, approximately {minus}55{per thousand} in the Moloi River, approximately {minus}62{per thousand} and approximately {minus}31{per thousand} in two swamp areas) are presented. The data are interpreted with the help of additional measurements of delta-C{sup 13} of CO{sub 2} gas, andmore » organic carbon in plant material, termite bodies, and termite fungus combs. The implications of these findings are related to the problem of studying the atmospheric methane budget. 40 refs., 2 figs. 5 tabs.« less

Liquid identification by Hilbert spectroscopy

NASA Astrophysics Data System (ADS)

Lyatti, M.; Divin, Y.; Poppe, U.; Urban, K.

2009-11-01

Fast and reliable identification of liquids is of great importance in, for example, security, biology and the beverage industry. An unambiguous identification of liquids can be made by electromagnetic measurements of their dielectric functions in the frequency range of their main dispersions, but this frequency range, from a few GHz to a few THz, is not covered by any conventional spectroscopy. We have developed a concept of liquid identification based on our new Hilbert spectroscopy and high- Tc Josephson junctions, which can operate at the intermediate range from microwaves to THz frequencies. A demonstration setup has been developed consisting of a polychromatic radiation source and a compact Hilbert spectrometer integrated in a Stirling cryocooler. Reflection polychromatic spectra of various bottled liquids have been measured at the spectral range of 15-300 GHz with total scanning time down to 0.2 s and identification of liquids has been demonstrated.

The Application of Advanced Geophysical Classification in Support of Munitions Response Program: An Outreach to Federal, State and Local Regulators and Tribal Governments

DTIC Science & Technology

2017-04-18

Industry’s Treatability Study 20 demonstration sites Over 30 datasets from 3 different sensors Former Lowry Bombing and Gunnery Range Former Camp...object by an external EM source, after the external EM source is removed. Polarizability values exist for each of the object’s three principal...The EM Signal We Measure 13 BUILDING STRONG®  Normalized response (polarizability) for excitation in object’s principal axis directions are the

Analysis of time-of-flight spectra

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

Gibson, E.M.; Foxon, C.T.; Zhang, J.

1990-07-01

A simplified method of data analysis for time of flight measurements of the velocity of molecular beams sources is described. This method does not require the complex data fitting previously used in such studies. The method is applied to the study of Pb molecular beams from a true Knudsen source and has been used to show that a VG Quadrupoles SXP300H mass spectrometer, when fitted with an open cross-beam ionizer, acts as an ideal density detector over a wide range of operating conditions.

Measuring the Impact of a Science Center on Its Community

ERIC Educational Resources Information Center

Falk, John H.; Needham, Mark D.

2011-01-01

A range of sources support science learning, including the formal education system, libraries, museums, nature and Science Centers, aquariums and zoos, botanical gardens and arboretums, television programs, film and video, newspapers, radio, books and magazines, the Internet, community and health organizations, environmental organizations, and…

Comparison of sources of submicron particle number concentrations measured at two sites in Rochester, NY.

PubMed

Kasumba, John; Hopke, Philip K; Chalupa, David C; Utell, Mark J

2009-09-01

Sources contributing to the submicron particles (100-470 nm) measured between January 2002 and December 2007 at two different New York State Department of Environmental Conservation (NYS DEC) sites in Rochester, NY were identified and apportioned using a bilinear receptor model, positive matrix factorization (PMF). Measurements of aerosol size distributions and number concentrations for particles in the size range of 10-500 nm have been made since December 2001 to date in Rochester. The measurements are being made using a scanning mobility particle sizer (SMPS) consisting of a DMA and a CPC (TSI models 3071 and 3010, respectively). From December 2001 to March 2004, particle measurements were made at the NYS DEC site in downtown Rochester, but it was moved to the eastside of Rochester in May 2004. Each measurement period was divided into three seasons i.e., winter (December, January, and February), summer (June, July, and August), and the transitional periods (March, April, May, September, October, and November) so as to avoid experimental uncertainty resulting from too large season-to-season variability in ambient temperature and solar photon intensity that would lead to unstable/non-stationary size distributions. Therefore, the seasons were analyzed independently for possible sources. Ten sources were identified at both sites and these include traffic, nucleation, residential/commercial heating, industrial emissions, secondary nitrate, ozone- rich secondary aerosol, secondary sulfate, regionally transported aerosol, and a mixed source of nucleation and traffic. These results show that the measured total outdoor particle number concentrations in Rochester generally vary with similar temporal patterns, suggesting that the central monitoring site data can be used to estimate outdoor exposure in other parts of the city.

Ultrasensitive measurement of microcantilever displacement below the shot-noise limit

DOE PAGES

Pooser, Raphael C.; Lawrie, Benjamin J.

2015-04-23

The displacement of micro-electro-mechanical-systems (MEMs) cantilevers is used to measure a variety of phe- nomena in devices ranging from force microscopes for single spin detection[1] to biochemical sensors[2] to un- cooled thermal imaging systems[3]. The displacement readout is often performed optically with segmented de- tectors or interference measurements. Until recently, var- ious noise sources have limited the minimum detectable displacement in MEMs systems, but it is now possible to minimize all other sources[4] so that the noise level of the coherent light eld, called the shot noise limit (SNL), becomes the dominant source. Light sources dis- playing quantum-enhanced statistics belowmore » this limit are available[5, 6], with applications in gravitational wave astronomy[7] and bioimaging[8], but direct displacement measurements of MEMS cantilevers below the SNL have been impossible until now. Here, we demonstrate the rst direct measurement of a MEMs cantilever displace- ment with sub-SNL sensitivity, thus enabling ultratrace sensing, imaging, and microscopy applications. By com- bining multi-spatial-mode quantum light sources with a simple dierential measurement, we show that sub-SNL MEMs displacement sensitivity is highly accessible com- pared to previous eorts that measured the displacement of macroscopic mirrors with very distinct spatial struc- tures crafted with multiple optical parametric ampliers and locking loops[9]. We apply this technique to a com- mercially available microcantilever in order to detect dis- placements 60% below the SNL at frequencies where the microcantilever is shot-noise-limited. These results sup- port a new class of quantum MEMS sensor whose ulti- mate signal to noise ratio is determined by the correla- tions possible in quantum optics systems.« less

Ultrasensitive measurement of microcantilever displacement below the shot-noise limit

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

Pooser, Raphael C.; Lawrie, Benjamin J.

The displacement of micro-electro-mechanical-systems (MEMs) cantilevers is used to measure a variety of phe- nomena in devices ranging from force microscopes for single spin detection[1] to biochemical sensors[2] to un- cooled thermal imaging systems[3]. The displacement readout is often performed optically with segmented de- tectors or interference measurements. Until recently, var- ious noise sources have limited the minimum detectable displacement in MEMs systems, but it is now possible to minimize all other sources[4] so that the noise level of the coherent light eld, called the shot noise limit (SNL), becomes the dominant source. Light sources dis- playing quantum-enhanced statistics belowmore » this limit are available[5, 6], with applications in gravitational wave astronomy[7] and bioimaging[8], but direct displacement measurements of MEMS cantilevers below the SNL have been impossible until now. Here, we demonstrate the rst direct measurement of a MEMs cantilever displace- ment with sub-SNL sensitivity, thus enabling ultratrace sensing, imaging, and microscopy applications. By com- bining multi-spatial-mode quantum light sources with a simple dierential measurement, we show that sub-SNL MEMs displacement sensitivity is highly accessible com- pared to previous eorts that measured the displacement of macroscopic mirrors with very distinct spatial struc- tures crafted with multiple optical parametric ampliers and locking loops[9]. We apply this technique to a com- mercially available microcantilever in order to detect dis- placements 60% below the SNL at frequencies where the microcantilever is shot-noise-limited. These results sup- port a new class of quantum MEMS sensor whose ulti- mate signal to noise ratio is determined by the correla- tions possible in quantum optics systems.« less

Low frequency wind noise contributions in measurement microphones.

PubMed

Raspet, Richard; Yu, Jiao; Webster, Jeremy

2008-03-01

In a previous paper [R. Raspet, et al., J. Acoust. Soc. Am. 119, 834-843 (2006)], a method was introduced to predict upper and lower bounds for wind noise measured in spherical wind-screens from the measured incident velocity spectra. That paper was restricted in that the predictions were only valid within the inertial range of the incident turbulence, and the data were from a measurement not specifically designed to test the predictions. This paper extends the previous predictions into the source region of the atmospheric wind turbulence, and compares the predictions to measurements made with a large range of wind-screen sizes. Predictions for the turbulence-turbulence interaction pressure spectrum as well as the stagnation pressure fluctuation spectrum are calculated from a form fit to the velocity fluctuation spectrum. While the predictions for turbulence-turbulence interaction agree well with measurements made within large (1.0 m) wind-screens, and the stagnation pressure predictions agree well with unscreened gridded microphone measurements, the mean shear-turbulence interaction spectra do not consistently appear in measurements.

Atomic Resonance Radiation Energetics Investigation as a Diagnostic Method for Non-Equilibrium Hypervelocity Flows

NASA Technical Reports Server (NTRS)

Meyer, Scott A.; Bershader, Daniel; Sharma, Surendra P.; Deiwert, George S.

1996-01-01

Absorption measurements with a tunable vacuum ultraviolet light source have been proposed as a concentration diagnostic for atomic oxygen, and the viability of this technique is assessed in light of recent measurements. The instrumentation, as well as initial calibration measurements, have been reported previously. We report here additional calibration measurements performed to study the resonance broadening line shape for atomic oxygen. The application of this diagnostic is evaluated by considering the range of suitable test conditions and requirements, and by identifying issues that remain to be addressed.

Photofission cross-section ratio measurement of 235 U/ 238 U using monoenergetic photons in the energy range of 9.0–16.6 MeV

DOE PAGES

Krishichayan,; Bhike, Megha; Finch, S. W.; ...

2017-05-01

Photofission cross-section ratios of 235U and 238U have been measured using monoenergetic photon beams from the High Intensity Gamma-ray Source facility at the Triangle Universities Nuclear Laboratory. These measurements have been performed in small energy steps between 9.0 and 16.6 MeV using a dual-fission ionization chamber. The measured cross-section ratios are compared with the previous experimental data as well as with the recent evaluated nuclear data library ENDF.

Evaluation of DCS III Transmission Alternatives, Phase 1B.

DTIC Science & Technology

1980-09-30

Most commonly used measure are straight and precision tubing, dielectric lining, and helix construction. These measures make the millimeter waveguide...channel tran- sistorized and microprocessor-controlled L5E. The broadband signal, either analog or digital, can be transmitted over a coaxial cable...kilowatts. One kind of mm source is travelling wave tubes ( TWT ) which are currently under development in the frequency range from 20 to 50 GHz with

High source levels and small active space of high-pitched song in bowhead whales (Balaena mysticetus).

PubMed

Tervo, Outi M; Christoffersen, Mads F; Simon, Malene; Miller, Lee A; Jensen, Frants H; Parks, Susan E; Madsen, Peter T

2012-01-01

The low-frequency, powerful vocalizations of blue and fin whales may potentially be detected by conspecifics across entire ocean basins. In contrast, humpback and bowhead whales produce equally powerful, but more complex broadband vocalizations composed of higher frequencies that suffer from higher attenuation. Here we evaluate the active space of high frequency song notes of bowhead whales (Balaena mysticetus) in Western Greenland using measurements of song source levels and ambient noise. Four independent, GPS-synchronized hydrophones were deployed through holes in the ice to localize vocalizing bowhead whales, estimate source levels and measure ambient noise. The song had a mean apparent source level of 185±2 dB rms re 1 µPa @ 1 m and a high mean centroid frequency of 444±48 Hz. Using measured ambient noise levels in the area and Arctic sound spreading models, the estimated active space of these song notes is between 40 and 130 km, an order of magnitude smaller than the estimated active space of low frequency blue and fin whale songs produced at similar source levels and for similar noise conditions. We propose that bowhead whales spatially compensate for their smaller communication range through mating aggregations that co-evolved with broadband song to form a complex and dynamic acoustically mediated sexual display.

Normalizing memory recall in fibromyalgia with rehearsal: a distraction-counteracting effect.

PubMed

Leavitt, Frank; Katz, Robert S

2009-06-15

To examine the impact of distraction on the retention of rehearsed information in patients with fibromyalgia syndrome (FMS). Data refer to the neurocognitive examination of 134 patients (91 with FMS and 43 control subjects) presenting with memory loss. Four neurocognitive measures free of distraction, along with 2 measures with added distraction, were completed. Differences in the retention of rehearsed and unrehearsed information with a source of distraction present were calculated. Patients with FMS showed normal cognitive functioning on verbal memory tests free of distraction. Adding a source of distraction caused unrefreshed information to be lost at a disproportionate rate in patients with FMS. Over 87% of patients with FMS scored in the impaired range on a task of unrehearsed verbal memory. Adding a source of distraction to well-rehearsed information produced a normal rate of recall in FMS. Rehearsal mechanisms are intact in patients with FMS and play beneficial roles in managing interference from a source of distraction. In the absence of rehearsal, a source of distraction added to unrefreshed information signals a remarkable level of cognitive deficit in FMS that goes undetected by conventionally relied-upon neurocognitive measures. We present a theory to promote understanding of the cognitive deficit of people with FMS based on reduced speed of lexical activation and poor recall after distraction.

High Source Levels and Small Active Space of High-Pitched Song in Bowhead Whales (Balaena mysticetus)

PubMed Central

Tervo, Outi M.; Christoffersen, Mads F.; Simon, Malene; Miller, Lee A.; Jensen, Frants H.; Parks, Susan E.; Madsen, Peter T.

2012-01-01

The low-frequency, powerful vocalizations of blue and fin whales may potentially be detected by conspecifics across entire ocean basins. In contrast, humpback and bowhead whales produce equally powerful, but more complex broadband vocalizations composed of higher frequencies that suffer from higher attenuation. Here we evaluate the active space of high frequency song notes of bowhead whales (Balaena mysticetus) in Western Greenland using measurements of song source levels and ambient noise. Four independent, GPS-synchronized hydrophones were deployed through holes in the ice to localize vocalizing bowhead whales, estimate source levels and measure ambient noise. The song had a mean apparent source level of 185±2 dB rms re 1 µPa @ 1 m and a high mean centroid frequency of 444±48 Hz. Using measured ambient noise levels in the area and Arctic sound spreading models, the estimated active space of these song notes is between 40 and 130 km, an order of magnitude smaller than the estimated active space of low frequency blue and fin whale songs produced at similar source levels and for similar noise conditions. We propose that bowhead whales spatially compensate for their smaller communication range through mating aggregations that co-evolved with broadband song to form a complex and dynamic acoustically mediated sexual display. PMID:23300591

The Measurement of the Flux and Spectrum of the Crab by HAWC

NASA Astrophysics Data System (ADS)

Smith, Andrew; HAWC Collaboration Collaboration

2017-01-01

The HAWC observatory was completed and began full operation in early 2015. Located at an elevation of 4100m, HAWC has an energy threshold for gamma-ray detection well below 1 TeV and a sensitivity to TeV-scale gamma-ray sources an order of magnitude better than previous air-shower arrays. The detector operates 24 hours/day and observes the overhead sky (2 sr), making it an ideal survey instrument. We describe the details of the high significance detection (>100 sigma) of the Crab PWN and explain in detail the measurement the VHE spectrum of this important gamma-ray source. At the high end of the VHE range, above 10 TeV, HAWC's sensitivity is better than that of IACTs due mainly to its large effective area and unprecedented exposure. Measuring the high energy behavior of this source is critical to the understanding of the acceleration dynamics and the environment in vicinity of the pulsar. Furthermore, as the Crab is bright, point-like and steady, as detected by VHE gamma-ray instruments, it serves as the best source for verification of detector performance and measurement of systematic errors. This presentation will also describe in detail the analysis methodology utilized by a number of presentations from the HAWC collaboration.

Acoustical evaluation of the NASA Lewis 9 by 15 foot low speed wind tunnel

NASA Technical Reports Server (NTRS)

Dahl, Milo D.; Woodward, Richard P.

1992-01-01

The test section of the NASA Lewis 9- by 15-Foot Low Speed Wind Tunnel was acoustically treated to allow the measurement of acoustic sources located within the tunnel test section under simulated free field conditions. The treatment was designed for high sound absorption at frequencies above 250 Hz and to withstand tunnel airflow velocities up to 0.2 Mach. Evaluation tests with no tunnel airflow were conducted in the test section to assess the performance of the installed treatment. This performance would not be significantly affected by low speed airflow. Time delay spectrometry tests showed that interference ripples in the incident signal resulting from reflections occurring within the test section average from 1.7 dB to 3.2 dB wide over a 500 to 5150 Hz frequency range. Late reflections, from upstream and downstream of the test section, were found to be insignificant at the microphone measuring points. For acoustic sources with low directivity characteristics, decay with distance measurements in the test section showed that incident free field behavior can be measured on average with an accuracy of +/- 1.5 dB or better at source frequencies from 400 Hz to 10 kHz. The free field variations are typically much smaller with an omnidirectional source.

Optimization of the method for assessment of brain perfusion in humans using contrast-enhanced reflectometry: multidistance time-resolved measurements

NASA Astrophysics Data System (ADS)

Milej, Daniel; Janusek, Dariusz; Gerega, Anna; Wojtkiewicz, Stanislaw; Sawosz, Piotr; Treszczanowicz, Joanna; Weigl, Wojciech; Liebert, Adam

2015-10-01

The aim of the study was to determine optimal measurement conditions for assessment of brain perfusion with the use of optical contrast agent and time-resolved diffuse reflectometry in the near-infrared wavelength range. The source-detector separation at which the distribution of time of flights (DTOF) of photons provided useful information on the inflow of the contrast agent to the intracerebral brain tissue compartments was determined. Series of Monte Carlo simulations was performed in which the inflow and washout of the dye in extra- and intracerebral tissue compartments was modeled and the DTOFs were obtained at different source-detector separations. Furthermore, tests on diffuse phantoms were carried out using a time-resolved setup allowing the measurement of DTOFs at 16 source-detector separations. Finally, the setup was applied in experiments carried out on the heads of adult volunteers during intravenous injection of indocyanine green. Analysis of statistical moments of the measured DTOFs showed that the source-detector separation of 6 cm is recommended for monitoring of inflow of optical contrast to the intracerebral brain tissue compartments with the use of continuous wave reflectometry, whereas the separation of 4 cm is enough when the higher-order moments of DTOFs are available.

Analysis of large system black box verification test data

NASA Technical Reports Server (NTRS)

Clapp, Kenneth C.; Iyer, Ravishankar Krishnan

1993-01-01

Issues regarding black box, large systems verification are explored. It begins by collecting data from several testing teams. An integrated database containing test, fault, repair, and source file information is generated. Intuitive effectiveness measures are generated using conventional black box testing results analysis methods. Conventional analysts methods indicate that the testing was effective in the sense that as more tests were run, more faults were found. Average behavior and individual data points are analyzed. The data is categorized and average behavior shows a very wide variation in number of tests run and in pass rates (pass rates ranged from 71 percent to 98 percent). The 'white box' data contained in the integrated database is studied in detail. Conservative measures of effectiveness are discussed. Testing efficiency (ratio of repairs to number of tests) is measured at 3 percent, fault record effectiveness (ratio of repairs to fault records) is measured at 55 percent, and test script redundancy (ratio of number of failed tests to minimum number of tests needed to find the faults) ranges from 4.2 to 15.8. Error prone source files and subsystems are identified. A correlational mapping of test functional area to product subsystem is completed. A new adaptive testing process based on real-time generation of the integrated database is proposed.

Environmental factors affecting corrosion of munitions

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

Bundy, K.; Bricka, M.; Morales, A.

1995-12-31

Spent small arms munitions have accumulated for years at outdoor firing ranges operated by the DoD and other groups. Used bullets are often subjected to moisture sources. There is increasing concern that accumulations of lead-based munitions represent potential sources of water and soil pollution. To understand both the severity of and solutions to this problem, it is necessary to measure how rapidly bullets corrode and to determine the soil variables affecting the process. In this study M16 bullets were buried in samples of soil taken from Louisiana army firing ranges. Four environmental conditions were simulated; rain water, acid rain, seamore » water, and 50% sea water/50% acid rain. The three electrode technique was used to measure the bullet corrosion. Graphite rods served as counter electrodes. A saturated calomel reference electrode was used along with a specially constructed salt bridge. Electrochemical measurements were conducted using a computer-controlled potentiostat to determine corrosion potential, soil resistance, and corrosion current. The rate of corrosion was found to markedly increase with decreasing soil pH and increasing chloride and moisture contents, with the chloride content being the most influential variable. High soil resistance and noble corrosion potential were found to be associated with low corrosion rates. This is important since both parameters can be readily measured in the field.« less

YouTube as a source of chronic obstructive pulmonary disease patient education: a social media content analysis.

PubMed

Stellefson, Michael; Chaney, Beth; Ochipa, Kathleen; Chaney, Don; Haider, Zeerak; Hanik, Bruce; Chavarria, Enmanuel; Bernhardt, Jay M

2014-05-01

The aim of the present study is to conduct a social media content analysis of chronic obstructive pulmonary disease (COPD) patient education videos on YouTube. A systematic search protocol was used to locate 223 videos. Two independent coders evaluated each video to determine topics covered, media source(s) of posted videos, information quality as measured by HONcode guidelines for posting trustworthy health information on the Internet, and viewer exposure/engagement metrics. Over half the videos (n = 113, 50.7%) included information on medication management, with far fewer videos on smoking cessation (n = 40, 17.9%). Most videos were posted by a health agency or organization (n = 128, 57.4%), and the majority of videos were rated as high quality (n = 154, 69.1%). HONcode adherence differed by media source (Fisher's exact test = 20.52, p = 0.01), however with user-generated content receiving the lowest quality scores. Overall level of user engagement as measured by number of "likes," "favorites," "dislikes," and user comments was low (median range = 0-3, interquartile range = 0-16) across all sources of media. Study findings suggest that COPD education via YouTube has the potential to reach and inform patients; however, existing video content and quality varies significantly. Future interventions should help direct individuals with COPD to engage with high-quality patient education videos on YouTube that are posted by reputable health organizations and qualified medical professionals. Patients should be educated to avoid and/or critically view low-quality videos posted by individual YouTube users who are not health professionals.