Total atmospheric ozone determined from spectral measurements of direct solar UV irradiance

NASA Astrophysics Data System (ADS)

Huber, Martin; Blumthaler, Mario; Ambach, Walter; Staehelin, Johannes

1995-01-01

With a double monochromator, high resolution spectral measurements of direct solar UV-irradiance were performed in Arosa during February and March, 1993. Total atmospheric ozone amount is determined by fitting model calculations to the measured spectra. The results are compared with the operationally performed measurements of a Dobson and a Brewer spectrometer. The total ozone amount determined from spectral measurements differs from the results of the Dobson instrument by -1.1±0.9% and from those of the Brewer instrument by -0.4±0.7%.

Theory of spectral radiance of pollutants at sea

NASA Technical Reports Server (NTRS)

1978-01-01

Remote measurement of soluble pollutants that change the color of the water in the sea is reported. The sensor is a spectral radiometer that flies over the polluted area and compares its spectral radiance to that of surrounding clean seawater. A quantitative analysis of the concentration of pollutants using the measured radiance of the sea compared to laboratory measurements of reflection and transmission spectra of the pollutants is presented. The quantities involved are defined and means for measuring them are described. The equations for remote sensing with a low-flying aircraft, in which case the absorption and radiance of intervening air is negligible are derived. High-flying aircraft and satellites, in which case the radiance of intervening air is the major problem are applied.

Comparison of a New Cobinamide-Based Method to a Standard Laboratory Method for Measuring Cyanide in Human Blood

PubMed Central

Swezey, Robert; Shinn, Walter; Green, Carol; Drover, David R.; Hammer, Gregory B.; Schulman, Scott R.; Zajicek, Anne; Jett, David A.; Boss, Gerry R.

2013-01-01

Most hospital laboratories do not measure blood cyanide concentrations, and samples must be sent to reference laboratories. A simple method is needed for measuring cyanide in hospitals. The authors previously developed a method to quantify cyanide based on the high binding affinity of the vitamin B12 analog, cobinamide, for cyanide and a major spectral change observed for cyanide-bound cobinamide. This method is now validated in human blood, and the findings include a mean inter-assay accuracy of 99.1%, precision of 8.75% and a lower limit of quantification of 3.27 µM cyanide. The method was applied to blood samples from children treated with sodium nitroprusside and it yielded measurable results in 88 of 172 samples (51%), whereas the reference laboratory yielded results in only 19 samples (11%). In all 19 samples, the cobinamide-based method also yielded measurable results. The two methods showed reasonable agreement when analyzed by linear regression, but not when analyzed by a standard error of the estimate or paired t-test. Differences in results between the two methods may be because samples were assayed at different times on different sample types. The cobinamide-based method is applicable to human blood, and can be used in hospital laboratories and emergency rooms. PMID:23653045

Influence of aerosols on surface reaching spectral irradiance and introduction to a new technique for estimating aerosol radiative forcing from spectral flux measurements

NASA Astrophysics Data System (ADS)

Rao, R. R.

2015-12-01

Aerosol radiative forcing estimates with high certainty are required in climate change studies. The approach in estimating the aerosol radiative forcing by using the chemical composition of aerosols is not effective as the chemical composition data with radiative properties are not widely available. In this study we look into the approach where ground based spectral radiation flux measurements along with an RT model is used to estimate radiative forcing. Measurements of spectral flux were made using an ASD spectroradiometer with 350 - 1050 nm wavelength range and 3nm resolution for around 54 clear-sky days during which AOD range was around 0.1 to 0.7. Simultaneous measurements of black carbon were also made using Aethalometer (Magee Scientific) which ranged from around 1.5 ug/m3 to 8 ug/m3. All the measurements were made in the campus of Indian Institute of Science which is in the heart of Bangalore city. The primary study involved in understanding the sensitivity of spectral flux to change in the mass concentration of individual aerosol species (Optical properties of Aerosols and Clouds -OPAC classified aerosol species) using the SBDART RT model. This made us clearly distinguish the region of influence of different aerosol species on the spectral flux. Following this, a new technique has been introduced to estimate an optically equivalent mixture of aerosol species for the given location. The new method involves an iterative process where the mixture of aerosol species are changed in OPAC model and RT model is run as long as the mixture which mimics the measured spectral flux within 2-3% deviation from measured spectral flux is obtained. Using the optically equivalent aerosol mixture and RT model aerosol radiative forcing is estimated. The new method is limited to clear sky scenes and its accuracy to derive an optically equivalent aerosol mixture reduces when diffuse component of flux increases. Our analysis also showed that direct component of spectral flux is

Modeling Soil Organic Carbon at Regional Scale by Combining Multi-Spectral Images with Laboratory Spectra.

PubMed

Peng, Yi; Xiong, Xiong; Adhikari, Kabindra; Knadel, Maria; Grunwald, Sabine; Greve, Mogens Humlekrog

2015-01-01

There is a great challenge in combining soil proximal spectra and remote sensing spectra to improve the accuracy of soil organic carbon (SOC) models. This is primarily because mixing of spectral data from different sources and technologies to improve soil models is still in its infancy. The first objective of this study was to integrate information of SOC derived from visible near-infrared reflectance (Vis-NIR) spectra in the laboratory with remote sensing (RS) images to improve predictions of topsoil SOC in the Skjern river catchment, Denmark. The second objective was to improve SOC prediction results by separately modeling uplands and wetlands. A total of 328 topsoil samples were collected and analyzed for SOC. Satellite Pour l'Observation de la Terre (SPOT5), Landsat Data Continuity Mission (Landsat 8) images, laboratory Vis-NIR and other ancillary environmental data including terrain parameters and soil maps were compiled to predict topsoil SOC using Cubist regression and Bayesian kriging. The results showed that the model developed from RS data, ancillary environmental data and laboratory spectral data yielded a lower root mean square error (RMSE) (2.8%) and higher R2 (0.59) than the model developed from only RS data and ancillary environmental data (RMSE: 3.6%, R2: 0.46). Plant-available water (PAW) was the most important predictor for all the models because of its close relationship with soil organic matter content. Moreover, vegetation indices, such as the Normalized Difference Vegetation Index (NDVI) and Enhanced Vegetation Index (EVI), were very important predictors in SOC spatial models. Furthermore, the 'upland model' was able to more accurately predict SOC compared with the 'upland & wetland model'. However, the separately calibrated 'upland and wetland model' did not improve the prediction accuracy for wetland sites, since it was not possible to adequately discriminate the vegetation in the RS summer images. We conclude that laboratory Vis

Modeling Soil Organic Carbon at Regional Scale by Combining Multi-Spectral Images with Laboratory Spectra

PubMed Central

Peng, Yi; Xiong, Xiong; Adhikari, Kabindra; Knadel, Maria; Grunwald, Sabine; Greve, Mogens Humlekrog

2015-01-01

There is a great challenge in combining soil proximal spectra and remote sensing spectra to improve the accuracy of soil organic carbon (SOC) models. This is primarily because mixing of spectral data from different sources and technologies to improve soil models is still in its infancy. The first objective of this study was to integrate information of SOC derived from visible near-infrared reflectance (Vis-NIR) spectra in the laboratory with remote sensing (RS) images to improve predictions of topsoil SOC in the Skjern river catchment, Denmark. The second objective was to improve SOC prediction results by separately modeling uplands and wetlands. A total of 328 topsoil samples were collected and analyzed for SOC. Satellite Pour l’Observation de la Terre (SPOT5), Landsat Data Continuity Mission (Landsat 8) images, laboratory Vis-NIR and other ancillary environmental data including terrain parameters and soil maps were compiled to predict topsoil SOC using Cubist regression and Bayesian kriging. The results showed that the model developed from RS data, ancillary environmental data and laboratory spectral data yielded a lower root mean square error (RMSE) (2.8%) and higher R2 (0.59) than the model developed from only RS data and ancillary environmental data (RMSE: 3.6%, R2: 0.46). Plant-available water (PAW) was the most important predictor for all the models because of its close relationship with soil organic matter content. Moreover, vegetation indices, such as the Normalized Difference Vegetation Index (NDVI) and Enhanced Vegetation Index (EVI), were very important predictors in SOC spatial models. Furthermore, the ‘upland model’ was able to more accurately predict SOC compared with the ‘upland & wetland model’. However, the separately calibrated ‘upland and wetland model’ did not improve the prediction accuracy for wetland sites, since it was not possible to adequately discriminate the vegetation in the RS summer images. We conclude that laboratory

Integrated Geophysical Measurements for Bioremediation Monitoring: Combining Spectral Induced Polarization, Nuclear Magnetic Resonance and Magnetic Methods

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

Keating, Kristina; Slater, Lee; Ntarlagiannis, Dimitris

2015-02-24

This documents contains the final report for the project "Integrated Geophysical Measurements for Bioremediation Monitoring: Combining Spectral Induced Polarization, Nuclear Magnetic Resonance and Magnetic Methods" (DE-SC0007049) Executive Summary: Our research aimed to develop borehole measurement techniques capable of monitoring subsurface processes, such as changes in pore geometry and iron/sulfur geochemistry, associated with remediation of heavy metals and radionuclides. Previous work has demonstrated that geophysical method spectral induced polarization (SIP) can be used to assess subsurface contaminant remediation; however, SIP signals can be generated from multiple sources limiting their interpretation value. Integrating multiple geophysical methods, such as nuclear magnetic resonance (NMR)more » and magnetic susceptibility (MS), with SIP, could reduce the ambiguity of interpretation that might result from a single method. Our research efforts entails combining measurements from these methods, each sensitive to different mineral forms and/or mineral-fluid interfaces, providing better constraints on changes in subsurface biogeochemical processes and pore geometries significantly improving our understanding of processes impacting contaminant remediation. The Rifle Integrated Field Research Challenge (IFRC) site was used as a test location for our measurements. The Rifle IFRC site is located at a former uranium ore-processing facility in Rifle, Colorado. Leachate from spent mill tailings has resulted in residual uranium contamination of both groundwater and sediments within the local aquifer. Studies at the site include an ongoing acetate amendment strategy, native microbial populations are stimulated by introduction of carbon intended to alter redox conditions and immobilize uranium. To test the geophysical methods in the field, NMR and MS logging measurements were collected before, during, and after acetate amendment. Next, laboratory NMR, MS, and SIP

Extreme ultraviolet spectral irradiance measurements since 1946

NASA Astrophysics Data System (ADS)

Schmidtke, G.

2015-03-01

In the physics of the upper atmosphere the solar extreme ultraviolet (EUV) radiation plays a dominant role controlling most of the thermospheric/ionospheric (T/I) processes. Since this part of the solar spectrum is absorbed in the thermosphere, platforms to measure the EUV fluxes became only available with the development of rockets reaching altitude levels exceeding 80 km. With the availability of V2 rockets used in space research, recording of EUV spectra started in 1946 using photographic films. The development of pointing devices to accurately orient the spectrographs toward the sun initiated intense activities in solar-terrestrial research. The application of photoelectric recording technology enabled the scientists placing EUV spectrometers aboard satellites observing qualitatively strong variability of the solar EUV irradiance on short-, medium-, and long-term scales. However, as more measurements were performed more radiometric EUV data diverged due to the inherent degradation of the EUV instruments with time. Also, continuous recording of the EUV energy input to the T/I system was not achieved. It is only at the end of the last century that there was progress made in solving the serious problem of degradation enabling to monitore solar EUV fluxes with sufficient radiometric accuracy. The data sets available allow composing the data available to the first set of EUV data covering a period of 11 years for the first time. Based on the sophisticated instrumentation verified in space, future EUV measurements of the solar spectral irradiance (SSI) are promising accuracy levels of about 5% and less. With added low-cost equipment, real-time measurements will allow providing data needed in ionospheric modeling, e.g., for correcting propagation delays of navigation signals from space to earth. Adding EUV airglow and auroral emission monitoring by airglow cameras, the impact of space weather on the terrestrial T/I system can be studied with a spectral terrestrial

Spectral purity study for IPDA lidar measurement of CO2

NASA Astrophysics Data System (ADS)

Ma, Hui; Liu, Dong; Xie, Chen-Bo; Tan, Min; Deng, Qian; Xu, Ji-Wei; Tian, Xiao-Min; Wang, Zhen-Zhu; Wang, Bang-Xin; Wang, Ying-Jian

2018-02-01

A high sensitivity and global covered observation of carbon dioxide (CO2) is expected by space-borne integrated path differential absorption (IPDA) lidar which has been designed as the next generation measurement. The stringent precision of space-borne CO2 data, for example 1ppm or better, is required to address the largest number of carbon cycle science questions. Spectral purity, which is defined as the ratio of effective absorbed energy to the total energy transmitted, is one of the most important system parameters of IPDA lidar which directly influences the precision of CO2. Due to the column averaged dry air mixing ratio of CO2 is inferred from comparison of the two echo pulse signals, the laser output usually accompanied by an unexpected spectrally broadband background radiation would posing significant systematic error. In this study, the spectral energy density line shape and spectral impurity line shape are modeled as Lorentz line shape for the simulation, and the latter is assumed as an unabsorbed component by CO2. An error equation is deduced according to IPDA detecting theory for calculating the system error caused by spectral impurity. For a spectral purity of 99%, the induced error could reach up to 8.97 ppm.

Spectral analysis of sinus arrhythmia - A measure of mental effort

NASA Technical Reports Server (NTRS)

Vicente, Kim J.; Craig Thornton, D.; Moray, Neville

1987-01-01

The validity of the spectral analysis of sinus arrhythmia as a measure of mental effort was investigated using a computer simulation of a hovercraft piloted along a river as the experimental task. Strong correlation was observed between the subjective effort-ratings and the heart-rate variability (HRV) power spectrum between 0.06 and 0.14 Hz. Significant correlations were observed not only between subjects but, more importantly, within subjects as well, indicating that the spectral analysis of HRV is an accurate measure of the amount of effort being invested by a subject. Results also indicate that the intensity of effort invested by subjects cannot be inferred from the objective ratings of task difficulty or from performance.

Laboratory absorption spectra of molecules at interstellar cloud temperatures - First measurements on CO at about 97 nm

NASA Technical Reports Server (NTRS)

Smith, P. L.; Yoshino, K.; Stark, G.; Ito, K.; Stevens, M. H.

1991-01-01

In the 91-100 nm spectral region, where absorption of photons by interstellar CO usually leads to dissociation, laboratory spectra obtained at 295 K show that most CO bands are both overlapped and perturbed. Reliable band oscillator strengths cannot be extracted from such spectra. As a consequence, synthetic extreme-ultraviolet absorption spectra for CO at the low temperatures that prevail in interstellar clouds are uncertain. A supersonic expansion technique has been used to cool CO to 30 K and three bands in the 97-nm region have been studied with high spectral resolution. The measured spectrum at 30 K is in reasonable agreement with some published modeled spectra, but the ratios of integrated cross sections are somewhat different from those determined from low resolution spectra obtained at 295 K, in which the bands are blended.

Spectral Induced Polarization Signatures of Ethanol in Sand-Clay Medium

EPA Science Inventory

The spectral Induced Polarization (SIP) method has previously been investigated as a tool for detecting physicochemical changes occurring as result of clay-organic interactions in porous media. We performed SIP measurements with a dynamic signal analyzer (NI-4551) on laboratory ...

A linear spectral matching technique for retrieving equivalent water thickness and biochemical constituents of green vegetation

NASA Technical Reports Server (NTRS)

Gao, Bo-Cai; Goetz, Alexander F. H.

1992-01-01

Over the last decade, technological advances in airborne imaging spectrometers, having spectral resolution comparable with laboratory spectrometers, have made it possible to estimate biochemical constituents of vegetation canopies. Wessman estimated lignin concentration from data acquired with NASA's Airborne Imaging Spectrometer (AIS) over Blackhawk Island in Wisconsin. A stepwise linear regression technique was used to determine the single spectral channel or channels in the AIS data that best correlated with measured lignin contents using chemical methods. The regression technique does not take advantage of the spectral shape of the lignin reflectance feature as a diagnostic tool nor the increased discrimination among other leaf components with overlapping spectral features. A nonlinear least squares spectral matching technique was recently reported for deriving both the equivalent water thicknesses of surface vegetation and the amounts of water vapor in the atmosphere from contiguous spectra measured with the Airborne Visible/Infrared Imaging Spectrometer (AVIRIS). The same technique was applied to a laboratory reflectance spectrum of fresh, green leaves. The result demonstrates that the fresh leaf spectrum in the 1.0-2.5 microns region consists of spectral components of dry leaves and the spectral component of liquid water. A linear least squares spectral matching technique for retrieving equivalent water thickness and biochemical components of green vegetation is described.

Optical characterization of Chinese hybrid rice using laser-induced fluorescence techniques-laboratory and remote-sensing measurements.

PubMed

Duan, Zheng; Peng, Ting; Zhu, Shiming; Lian, Ming; Li, Yiyun; Wei, Fu; Xiong, Jiabao; Svanberg, Sune; Zhao, Quanzhi; Hu, Jiandong; Zhao, Guangyu

2018-05-01

Chinese hybrid rice of different varieties, growing in paddies in the Pingqiao district, north of Xinyang city, Henan province, China, was studied in detailed spectroscopic characteristics using laser-induced fluorescence. The base for the studies was the new South China Normal University mobile lidar laboratory, which was dispatched on site, providing facilities both for laboratory studies using a 405 nm excitation source as well as remote sensing measurements at ranges from around 40 m-120 m, mostly employing the 532 nm output from a Nd:YAG laser. We, in particular, studied the spectral influence of the species varieties as well as the level of nitrogen fertilization supplied. Specially developed contrast functions as well as multivariate techniques with principal components and Fisher's discriminate analyses were applied, and useful characterization of the rice could be achieved. The chlorophyll content mapping of the 30 zones was obtained with the remote sensing measurements.

Calibration and evaluation of CCD spectroradiometers for ground-based and airborne measurements of spectral actinic flux densities

NASA Astrophysics Data System (ADS)

Bohn, Birger; Lohse, Insa

2017-09-01

The properties and performance of charge-coupled device (CCD) array spectroradiometers for the measurement of atmospheric spectral actinic flux densities (280-650 nm) and photolysis frequencies were investigated. These instruments are widely used in atmospheric research and are suitable for aircraft applications because of high time resolutions and high sensitivities in the UV range. The laboratory characterization included instrument-specific properties like the wavelength accuracy, dark signal, dark noise and signal-to-noise ratio (SNR). Spectral sensitivities were derived from measurements with spectral irradiance standards. The calibration procedure is described in detail, and a straightforward method to minimize the influence of stray light on spectral sensitivities is introduced. From instrument dark noise, minimum detection limits ≈ 1 × 1010 cm-2 s-1 nm-1 were derived for spectral actinic flux densities at wavelengths around 300 nm (1 s integration time). As a prerequisite for the determination of stray light under field conditions, atmospheric cutoff wavelengths were defined using radiative transfer calculations as a function of the solar zenith angle (SZA) and total ozone column (TOC). The recommended analysis of field data relies on these cutoff wavelengths and is also described in detail taking data from a research flight on HALO (High Altitude and Long Range Research Aircraft) as an example. An evaluation of field data was performed by ground-based comparisons with a double-monochromator-based, highly sensitive reference spectroradiometer. Spectral actinic flux densities were compared as well as photolysis frequencies j(NO2) and j(O1D), representing UV-A and UV-B ranges, respectively. The spectra expectedly revealed increased daytime levels of stray-light-induced signals and noise below atmospheric cutoff wavelengths. The influence of instrument noise and stray-light-induced noise was found to be insignificant for j(NO2) and rather limited for j(O1D

Correction of pathlength amplification in the filter-pad technique for measurements of particulate absorption coefficient in the visible spectral region.

PubMed

Stramski, Dariusz; Reynolds, Rick A; Kaczmarek, Sławomir; Uitz, Julia; Zheng, Guangming

2015-08-01

Spectrophotometric measurement of particulate matter retained on filters is the most common and practical method for routine determination of the spectral light absorption coefficient of aquatic particles, a_p(λ), at high spectral resolution over a broad spectral range. The use of differing geometrical measurement configurations and large variations in the reported correction for pathlength amplification induced by the particle/filter matrix have hindered adoption of an established measurement protocol. We describe results of dedicated laboratory experiments with a diversity of particulate sample types to examine variation in the pathlength amplification factor for three filter measurement geometries; the filter in the transmittance configuration (T), the filter in the transmittance-reflectance configuration (T-R), and the filter placed inside an integrating sphere (IS). Relationships between optical density measured on suspensions (OD_s) and filters (OD_f) within the visible portion of the spectrum were evaluated for the formulation of pathlength amplification correction, with power functions providing the best functional representation of the relationship for all three geometries. Whereas the largest uncertainties occur in the T method, the IS method provided the least sample-to-sample variability and the smallest uncertainties in the relationship between OD_s and OD_f. For six different samples measured with 1 nm resolution within the light wavelength range from 400 to 700 nm, a median error of 7.1% is observed for predicted values of OD_s using the IS method. The relationships established for the three filter-pad methods are applicable to historical and ongoing measurements; for future work, the use of the IS method is recommended whenever feasible.

Spectral and radiometric calibration of the Airborne Visible/Infrared Imaging Spectrometer

NASA Technical Reports Server (NTRS)

Vane, Gregg; Chrien, Thomas G.; Miller, Edward A.; Reimer, John H.

1987-01-01

The laboratory spectral and radiometric calibration of the AVIRIS science data collected since 1987 is described. The instrumentation and procedures used in the calibration are discussed and the accuracy achieved in the laboratory as determined by measurement and calculation is compared with the requirements. Instrument performance factors affecting radiometry are described. The paper concludes with a discussion of future plans.

Spectral Measurements of PMCs from SBUV/2 Instruments

NASA Technical Reports Server (NTRS)

DeLand, Matthew T.; Shettle, Eric P.; Thomas, Gary E.; Olivero, John J.

2006-01-01

The SBUV/2 (Solar Backscattered Ultraviolet, model 2) instrument is designed to monitor ozone stratospheric profile and total column ozone using measurements of the Earth's backscattered ultraviolet albedo. We have previously demonstrated that the normal radiance measurements from SBUV/2 instruments, which sample 12 discrete wavelengths between 252 and 340 nm during each scan, can be used to identify polar mesospheric clouds (PMCs). Some SBUV/2 instruments also periodically view the earth in continuous scan mode, covering the wavelength range 160-400 nm with 0.15 nm sampling. Analysis of these data show PMC occurrence rates similar to the normal discrete scan results, although the observation technique reduces the number of daily measurements by a factor of six. PMC observed by SBUV/2 instruments show a monotonic variation in the residual spectral albedo over the wavelength range 250 300 nm, with maximum enhancements of 10 15% at 250 nm. This result is consistent with microphysical model predictions from Jensen [1989. A numerical model of polar mesospheric cloud formation and evolution, Ph. D. Thesis, University of Colorado]. We find no evidence for a systematic localized increase in PMC residual albedo for wavelengths near 260 nm, in contrast to the recently reported results from the MSX UVISI instrument [Carbary J.F., et al., 2004. Evidence for bimodal particle distribution from the spectra of polar mesospheric clouds. Geophysics Research. Letters 31, L13108]. This result is observed for three different SBUV/2 instruments in both Northern and Southern Hemisphere data over a 13-year span. Our Mie scattering calculations show that the location and magnitude of the 260 nm hump feature is dependent upon the specific scattering angles appropriate to the MSX measurements. Although it explains the MSX spectrum, the bimodal size distribution proposed by Carbary et al. (2004), cannot explain the lack of scattering angle dependence of the SBUV/2 spectral shapes. The

Laboratory Simulations and Spectral Analyses of Space Weathering of Non-Ice Materials on Ocean Worlds

NASA Astrophysics Data System (ADS)

Wing, B. R.; Shusterman, M. L.; Irvin, B. L.; Hibbitts, C.

2016-12-01

Airless solar system bodies are subjected to bombardment by high-energy particles from the solar wind and for Galilean satellites, from the Jovian magnetosphere. These keV-MeV electrons and ions damage the upper microns of the exposed surface, resulting in physical, chemical, and spectral alterations that may confound interpretations of mineralogical properties. We conducted experiments simulating space weathering by energetic electrons for characterizing the spectral effects from the UV through the mid-IR; wavelengths commonly used to determine compositions of airless bodies. We bombarded analog non-ice materials with 40 keV electrons under high vacuum conditions for a period of 48-96 hours at a fluence of 80 μA. Spectral measurements were obtained at UV, VIS-SWIR, and NIR-MIR ranges from 0.14-5.0 μm using a McPherson 302 monochrometer, an SVC fiber-fed point spectrometer, and a Bruker Vertex 70 FTIR, respectively. The monochrometer and FTIR measurements were obtained before, during, and after irradiation, while the sample was under vacuum at 1e-7 torr. SVC measurements were obtained in a separate apparatus under an N2-purged environment before and after irradiation. The experiments were conducted to develop a better understanding of how exposure to particulate bombardment may affect the spectral features of airless bodies and subsequent interpretation of composition. Our results characterize the spectral nature of radiation-induced color centers, or Farbe-centers, that are active in the NUV-VIS-NIR wavelength range and inactive in the SWIR-MIR wavelength range. We confirmed the discoloration is due to the formation of F-centers rather than trace contamination such as iron, by analyzing samples under scanning electron microscope and X-ray spectrometer.

Effectiveness of Spectral Similarity Measures to Develop Precise Crop Spectra for Hyperspectral Data Analysis

NASA Astrophysics Data System (ADS)

Chauhan, H.; Krishna Mohan, B.

2014-11-01

The present study was undertaken with the objective to check effectiveness of spectral similarity measures to develop precise crop spectra from the collected hyperspectral field spectra. In Multispectral and Hyperspectral remote sensing, classification of pixels is obtained by statistical comparison (by means of spectral similarity) of known field or library spectra to unknown image spectra. Though these algorithms are readily used, little emphasis has been placed on use of various spectral similarity measures to select precise crop spectra from the set of field spectra. Conventionally crop spectra are developed after rejecting outliers based only on broad-spectrum analysis. Here a successful attempt has been made to develop precise crop spectra based on spectral similarity. As unevaluated data usage leads to uncertainty in the image classification, it is very crucial to evaluate the data. Hence, notwithstanding the conventional method, the data precision has been performed effectively to serve the purpose of the present research work. The effectiveness of developed precise field spectra was evaluated by spectral discrimination measures and found higher discrimination values compared to spectra developed conventionally. Overall classification accuracy for the image classified by field spectra selected conventionally is 51.89% and 75.47% for the image classified by field spectra selected precisely based on spectral similarity. KHAT values are 0.37, 0.62 and Z values are 2.77, 9.59 for image classified using conventional and precise field spectra respectively. Reasonable higher classification accuracy, KHAT and Z values shows the possibility of a new approach for field spectra selection based on spectral similarity measure.

Ultraviolet spectral reflectance of carbonaceous materials

NASA Astrophysics Data System (ADS)

Applin, Daniel M.; Izawa, Matthew R. M.; Cloutis, Edward A.; Gillis-Davis, Jeffrey J.; Pitman, Karly M.; Roush, Ted L.; Hendrix, Amanda R.; Lucey, Paul G.

2018-06-01

A number of planetary spacecraft missions have carried instruments with sensors covering the ultraviolet (UV) wavelength range. However, there exists a general lack of relevant UV reflectance laboratory data to compare against these planetary surface remote sensing observations in order to make confident material identifications. To address this need, we have systematically analyzed reflectance spectra of carbonaceous materials in the 200-500 nm spectral range, and found spectral-compositional-structural relationships that suggest this wavelength region could distinguish between otherwise difficult-to-identify carbon phases. In particular (and by analogy with the infrared spectral region), large changes over short wavelength intervals in the refractive indices associated with the trigonal sp2π-π* transition of carbon can lead to Fresnel peaks and Christiansen-like features in reflectance. Previous studies extending to shorter wavelengths also show that anomalous dispersion caused by the σ-σ* transition associated with both the trigonal sp2 and tetrahedral sp3 sites causes these features below λ = 200 nm. The peak wavelength positions and shapes of π-π* and σ-σ* features contain information on sp3/sp2, structure, crystallinity, and powder grain size. A brief comparison with existing observational data indicates that the carbon fraction of the surface of Mercury is likely amorphous and submicroscopic, as is that on the surface of the martian satellites Phobos and Deimos, and possibly comet 67P/Churyumov-Gerasimenko, while further coordinated observations and laboratory experiments should refine these feature assignments and compositional hypotheses. The new laboratory diffuse reflectance data reported here provide an important new resource for interpreting UV reflectance measurements from planetary surfaces throughout the solar system, and confirm that the UV can be rich in important spectral information.

Fluorescence emission spectral measurements for the detection of oil on shore

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

Balick, L.K.; Di Benedetto, J.A.; Lutz, S.S.

1997-06-01

The US DOE Special Technologies Laboratory is developing an airborne Laser-Induced Fluorescence Imaging (LIFI) system to support environmental management of government Utilities. This system, or a system to be derived from it, is being evaluated for its potential to detect spilled oils on shore, in wetlands, and on ice. To more fully understand the detectivity of oil spills, emphasis has been placed on the spectral contrast between the oil signatures and signatures associated with the natural backgrounds (sand, vegetation, etc.). To support this evaluation, two series of controlled measurements have been performed to provide rigorous characterization of the excitation-emission propertiesmore » of some oils and background materials, and to look at the effects of weathering of oil on terrestrial background materials. Oil targets included a heavy crude oil, diesel, kerosene, and aviation fuel and backgrounds included beach sand, straw, mud, tar and kelp. Fluorescence of oil on background materials decreases rapidly over the first few days of exposure to the environment and is more rapid than for neat oil samples.« less

Fluorescence emission spectral measurements for the detection of oil on shore

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

Balick, L.K.; Di Benedetto, J.A.; Lutz, S.S.

1996-12-31

The U.S. DOE Special Technologies Laboratory is developing an airborne Laser-Induced Fluorescence Imaging (LIFI) system to support environmental management of government facilities. This system, or a system to be derived from it, is being evaluated for its potential to detect spilled oils oN shore, in wetlands, and on ice. To more fully understand the detectivity of oil spills, emphasis has been placed on the spectral contrast between the oil signatures and signatures associated with the natural backgrounds (sand, vegetation, etc.). To support this evaluation, two series of controlled measurements have been performed to provide rigorous characterization of the excitation-emission propertiesmore » of some oils and background materials, and to look at the effects of weathering of oil on terrestrial background materials. Oil targets included a heavy crude oil, diesel, kerosene, and aviation fuel and backgrounds included beach sand, straw, mud, tar and kelp. Fluorescence of oil on background materials decreases rapidly over the first few days of exposure to the environment and is more rapid than for neat oil samples.« less

Two Long-Wave Infrared Spectral Polarimeters for Use in Understanding Polarization Phenomenology

DTIC Science & Technology

2002-05-01

3550 Aberdeen SE Kirtland Air Force Base, New Mexico 87117 Abstract. Spectrally varying long-wave infrared ( LWIR ) polarization measurements can be used...to identify materials and to discriminate samples from a cluttered background. Two LWIR instruments have been built and fielded by the Air Force...Research Laboratory: a multispectral LWIR imaging polarimeter (LIP) and a full-Stokes Fourier transform in- frared (FTIR) spectral polarimeter (FSP

Measured Polarized Spectral Responsivity of JPSS J1 VIIRS Using the NIST T-SIRCUS

NASA Technical Reports Server (NTRS)

McIntire, Jeff; Young, James B.; Moyer, David; Waluschka, Eugene; Xiong, Xiaoxiong

2015-01-01

Recent pre-launch measurements performed on the Joint Polar Satellite System (JPSS) J1 Visible Infrared Imaging Radiometer Suite (VIIRS) using the National Institute of Standards and Technology (NIST) Traveling Spectral Irradiance and Radiance Responsivity Calibrations Using Uniform Sources (T-SIRCUS) monochromatic source have provided wavelength dependent polarization sensitivity for select spectral bands and viewing conditions. Measurements were made at a number of input linear polarization states (twelve in total) and initially at thirteen wavelengths across the bandpass (later expanded to seventeen for some cases). Using the source radiance information collected by an external monitor, a spectral responsivity function was constructed for each input linear polarization state. Additionally, an unpolarized spectral responsivity function was derived from these polarized measurements. An investigation of how the centroid, bandwidth, and detector responsivity vary with polarization state was weighted by two model input spectra to simulate both ground measurements as well as expected on-orbit conditions. These measurements will enhance our understanding of VIIRS polarization sensitivity, improve the design for future flight models, and provide valuable data to enhance product quality in the post-launch phase.

Laboratory Measurements of the 940, 1130, and 1370 nm Water Vapor Absorption Band Profiles

NASA Technical Reports Server (NTRS)

Giver, Lawrence P.; Gore, Warren J.; Pilewskie, P.; Freedman, R. S.; Chackerian, C., Jr.; Varanasi, P.

2001-01-01

We have used the solar spectral flux radiometer (SSFR) flight instrument with the Ames 25 meter base-path White cell to obtain about 20 moderate resolution (8 nm) pure water vapor spectra from 650 to 1650 nm, with absorbing paths from 806 to 1506 meters and pressures up to 14 torr. We also obtained a set at 806 meters with several different air-broadening pressures. Model simulations were made for the 940, 1130, and 1370 nm absorption bands for some of these laboratory conditions using the Rothman, et al HITRAN-2000 linelist. This new compilation of HITRAN includes new intensity measurements for the 940 nm region. We compared simulations for our spectra of this band using HITRAN-2000 with simulations using the prior HITRAN-1996. The simulations of the 1130 nm band show about 10% less absorption than we measured. There is some evidence that the total intensity of this band is about 38% stronger than the sum of the HITRAN line intensities in this region. In our laboratory conditions the absorption depends approximately on the square root of the intensity. Thus, our measurements agree that the band is stronger than tabulated in HITRAN, but by about 20%, substantially less than the published value. Significant differences have been shown between Doppler-limited resolution spectra of the 1370 nm band obtained at the Pacific Northwest National Laboratory and HITRAN simulations. Additional new intensity measurements in this region are continuing to be made. We expect the simulations of our SSFR lab data of this band will show the relative importance of improving the HITRAN line intensities of this band for atmospheric measurements.

[Research on NIR equivalent spectral measurement].

PubMed

Wang, Zhi-Hong; Liu, Jie; Sun, Yu-Yang; Teng, Fei; Lin, Jun

2013-04-01

When the spectra of the diffuse reflectance of low reflectivity samples or the transmittance of low transmisivity samples are measured by a portable near infrared (NIR) spectrometer, because there is the noise of the spectrometer, the smaller the reflectance or transmittance of the sample, the lower its SNR. Even if treated by denoise methods, the spectra can not meet the requirement of NIR analysis. So the equivalent spectrum measure method was researched. Based on the intensity of the reflected or transmitted signal by the sample under the traditional measure conditions, the light current of the spectrometer was enlarged, and then the signal of the measured sample increased; the reflected or transmitted light of the measure reference was reduced to avoid the signal of the measure reference over range. Moreover the equivalent spectrum of the sample was calculated in order to make it identical with the spectrum measured by traditional method. Thus the NIR spectral SNR was improved. The results of theory analysis and experiments show that if the light signal of the spectrometer was properly increased according to the reflected or transmitted signal of the low reflectivity or transmisivity sample, the equivalent spectrum was the same as the spectrum measured by traditional method and its SNR was improved.

Traveling reference spectroradiometer for routine quality assurance of spectral solar ultraviolet irradiance measurements.

PubMed

Gröbner, Julian; Schreder, Josef; Kazadzis, Stelios; Bais, Alkiviadis F; Blumthaler, Mario; Görts, Peter; Tax, Rick; Koskela, Tapani; Seckmeyer, Gunther; Webb, Ann R; Rembges, Diana

2005-09-01

A transportable reference spectroradiometer for measuring spectral solar ultraviolet irradiance has been developed and validated. The expanded uncertainty of solar irradiance measurements with this reference spectroradiometer, based on the described methodology, is 8.8% to 4.6%, depending on the wavelength and the solar zenith angle. The accuracy of the spectroradiometer was validated by repeated site visits to two European UV monitoring sites as well as by regular comparisons with the reference spectroradiometer of the European Reference Centre for UV radiation measurements in Ispra, Italy. The spectral solar irradiance measurements of the Quality Assurance of Spectral Ultraviolet Measurements in Europe through the Development of a Transportable Unit (QASUME) spectroradiometer and these three spectroradiometers have agreed to better than 6% during the ten intercomparison campaigns held from 2002 to 2004. If the differences in irradiance scales of as much as 2% are taken into account, the agreement is of the order of 4% over the wavelength range of 300-400 nm.

In Situ Measurements of Spectral Emissivity of Materials for Very High Temperature Reactors

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

G. Cao; S. J. Weber; S. O. Martin

2011-08-01

An experimental facility for in situ measurements of high-temperature spectral emissivity of materials in environments of interest to the gas-cooled very high temperature reactor (VHTR) has been developed. The facility is capable of measuring emissivities of seven materials in a single experiment, thereby enhancing the accuracy in measurements due to even minor systemic variations in temperatures and environments. The system consists of a cylindrical silicon carbide (SiC) block with seven sample cavities and a deep blackbody cavity, a detailed optical system, and a Fourier transform infrared spectrometer. The reliability of the facility has been confirmed by comparing measured spectral emissivitiesmore » of SiC, boron nitride, and alumina (Al2O3) at 600 C against those reported in literature. The spectral emissivities of two candidate alloys for VHTR, INCONEL{reg_sign} alloy 617 (INCONEL is a registered trademark of the Special Metals Corporation group of companies) and SA508 steel, in air environment at 700 C were measured.« less

Laboratory Measurements of the Dielectronic Recombination Satellite Transitions of He-Like FE XXV and H-Like FE XXVI

NASA Technical Reports Server (NTRS)

Gu, M. F.; Beiersdorfer, P.; Brown, G. V.; Graf, A.; Kelley, R. I.; Kilbourne, C. A.; Porter, F. S.; Kahn, S. M,

2012-01-01

We present laboratory spectra of dielectronic recombination (DR) satellite transitions attached to the He-like and H-like iron resonance lines obtained with the NASA Goddard Space Flight Center X-ray calorimeter and produced by a thermal plasma simu1ation technique on the EBIT-I electron beam ion trap at the Lawrence Livermore National Laboratory. We demonstrate that the calorimeter has sufficient spectral resolution in the 6-9 keV range to provide reliable measurements not only of standard DR satellite to resonance line intensities but also of DR satellite to DR satellite ratios that can be used to diagnose nonthermal electron distributions. Electron temperatures derived from the measured line intensities are consistent with the temperature of the simulated plasma. Temperature measurements based on DR satellite transitions have significant advantages over those based on collisional ionization equilibrium or continuum shape. Thus, successful demonstration of this method with the X-ray calorimeter is an important step fur its application in X-ray astronomy.

Spectral deconvolution and operational use of stripping ratios in airborne radiometrics.

PubMed

Allyson, J D; Sanderson, D C

2001-01-01

Spectral deconvolution using stripping ratios for a set of pre-defined energy windows is the simplest means of reducing the most important part of gamma-ray spectral information. In this way, the effective interferences between the measured peaks are removed, leading, through a calibration, to clear estimates of radionuclide inventory. While laboratory measurements of stripping ratios are relatively easy to acquire, with detectors placed above small-scale calibration pads of known radionuclide concentrations, the extrapolation to measurements at altitudes where airborne survey detectors are used bring difficulties such as air-path attenuation and greater uncertainties in knowing ground level inventories. Stripping ratios are altitude dependent, and laboratory measurements using various absorbers to simulate the air-path have been used with some success. Full-scale measurements from an aircraft require a suitable location where radionuclide concentrations vary little over the field of view of the detector (which may be hundreds of metres). Monte Carlo simulations offer the potential of full-scale reproduction of gamma-ray transport and detection mechanisms. Investigations have been made to evaluate stripping ratios using experimental and Monte Carlo methods.

Influence of aerosols on surface reaching spectral irradiance and introduction to a new technique of estimating aerosol radiative forcing from high resolution spectral flux measurements

NASA Astrophysics Data System (ADS)

Rao, Roshan

2016-04-01

Aerosol radiative forcing estimates with high certainty are required in climate change studies. The approach in estimating the aerosol radiative forcing by using the chemical composition of aerosols is not effective as the chemical composition data with radiative properties are not widely available. We look into the approach where ground based spectral radiation flux measurement is made and along with an Radtiative transfer (RT) model, radiative forcing is estimated. Measurements of spectral flux were made using an ASD spectroradiometer with 350 - 1050 nm wavelength range and a 3nm resolution during around 54 clear-sky days during which AOD range was around 0.01 to 0.7. Simultaneous measurements of black carbon were also made using Aethalometer (Magee Scientific) which ranged from around 1.5 ug/m3 to 8 ug/m3. The primary study involved in understanding the sensitivity of spectral flux due to change in individual aerosol species (Optical properties of Aerosols and Clouds (OPAC) classified aerosol species) using the SBDART RT model. This made us clearly distinguish the influence of different aerosol species on the spectral flux. Following this, a new technique has been introduced to estimate an optically equivalent mixture of aerosol species for the given location. The new method involves matching different combinations of aerosol species in OPAC model and RT model as long as the combination which gives the minimum root mean squared deviation from measured spectral flux is obtained. Using the optically equivalent aerosol mixture and RT model, aerosol radiative forcing is estimated. Also an alternate method to estimate the spectral SSA is discussed. Here, the RT model, the observed spectral flux and spectral AOD is used. Spectral AOD is input to RT model and SSA is varied till the minimum root mean squared difference between observed and simulated spectral flux from RT model is obtained. The methods discussed are limited to clear sky scenes and its accuracy to derive

Refractive index measurements in absorbing media with white light spectral interferometry.

PubMed

Arosa, Yago; Lago, Elena López; de la Fuente, Raúl

2018-03-19

White light spectral interferometry is applied to measure the refractive index in absorbing liquids in the spectral range of 400-1000 nm. We analyze the influence of absorption on the visibility of interferometric fringes and, accordingly, on the measurement of the refractive index. Further, we show that the refractive index in the absorption band can be retrieved by a two-step process. The procedure requires the use of two samples of different thickness, the thicker one to retrieve the refractive index in the transparent region and the thinnest to obtain the data in the absorption region. First, the refractive index values are retrieved with good accuracy in the transparent region of the material for 1-mm-thick samples. Second, these refractive index values serve also to precisely calculate the thickness of a thinner sample (~150 µm) since the accuracy of the methods depends strongly on the thickness of the sample. Finally, the refractive index is recovered for the entire spectral range.

Fiberoptic probe and system for spectral measurements

DOEpatents

Dai, Sheng; Young, Jack P.

1998-01-01

A fused fiberoptic probe, a system, method and embodiments thereof for conducting spectral measurements are disclosed. The fused fiberoptic probe comprises a probe tip having a specific geometrical configuration, an exciting optical fiber and at least one collection optical fiber fused within a housing, preferrably silica. The specific geometrical configurations in which the probe tip can be shaped include a slanted probe tip with an angle greater than 0.degree., an inverted cone-shaped probe tip, and a lens head.

Fiberoptic probe and system for spectral measurements

DOEpatents

Dai, S.; Young, J.P.

1998-10-13

A fused fiberoptic probe, a system, method and embodiments thereof for conducting spectral measurements are disclosed. The fused fiberoptic probe comprises a probe tip having a specific geometrical configuration, an exciting optical fiber and at least one collection optical fiber fused within a housing, preferably silica. The specific geometrical configurations in which the probe tip can be shaped include a slanted probe tip with an angle greater than 0{degree}, an inverted cone-shaped probe tip, and a lens head. 12 figs.

Extensive goniometric spectral measurements at desert sites for military engineering

NASA Astrophysics Data System (ADS)

Berry, T. E.; Morgan, J. C.; Furey, J. S.; DeMoss, T. A.; Kelley, J. R.; McKenna, J. R.

2012-10-01

Remote-sensing technology designed to exploit disturbed earth signatures has become extremely useful in the detection of disturbed soil in military areas of operation. Soil reflectance can be exploited for this purpose and is dependent on atmospheric conditions. An understanding of the in situ soil background is vital to any type of change detection. Researchers from the Engineering Research and Development Center (ERDC) conducted OCONUS soil spectral measurements at ten sites in Afghanistan from July to November, 2011. Sampling sites were chosen on the basis of geomorphic setting, surface-soil characteristics, and field-expedient conditions. Goniometric spectral measurements at these sites have provided high quality bi-directional reflectance data, and their analyses are presented in the context of threat recognition and discrimination. These data can also provide the basis for BDRF model validation. Most spectral data were acquired under ambient solar lighting, but other data were collected at night and under artificial illumination conditions. Bidirectional measurements of soil reflectance in the VIS/NIR and SWIR were taken using the University of Lethbridge Goniometer System (ULGS) at dawn, mid-day, dusk and after sunset with a light. Soil surface roughness and reflectance varied, depending on the presence of desert varnish and desert pavement at some sites. Sun angle and dust and smoke in the atmosphere impacted soil reflectance and noise in the SWIR part of the light spectrum, in particular. The presence of minerals such as calcium carbonate, gypsum, and oxidized iron in the subsurface directly impacted reflectance measurements in disturbed soil.

Interpreting spectral unmixing coefficients: From spectral weights to mass fractions

NASA Astrophysics Data System (ADS)

Grumpe, Arne; Mengewein, Natascha; Rommel, Daniela; Mall, Urs; Wöhler, Christian

2018-01-01

It is well known that many common planetary minerals exhibit prominent absorption features. Consequently, the analysis of spectral reflectance measurements has become a major tool of remote sensing. Quantifying the mineral abundances, however, is not a trivial task. The interaction between the incident light rays and particulate surfaces, e.g., the lunar regolith, leads to a non-linear relationship between the reflectance spectra of the pure minerals, the so-called ;endmembers;, and the surface's reflectance spectrum. It is, however, possible to transform the non-linear reflectance mixture into a linear mixture of single-scattering albedos of the Hapke model. The abundances obtained by inverting the linear single-scattering albedo mixture may be interpreted as volume fractions which are weighted by the endmember's extinction coefficient. Commonly, identical extinction coefficients are assumed throughout all endmembers and the obtained volume fractions are converted to mass fractions using either measured or assumed densities. In theory, the proposed method may cover different grain sizes if each grain size range of a mineral is treated as a distinct endmember. Here, we present a method to transform the mixing coefficients to mass fractions for arbitrary combinations of extinction coefficients and densities. The required parameters are computed from reflectance measurements of well defined endmember mixtures. Consequently, additional measurements, e.g., the endmember density, are no longer required. We evaluate the method based on laboratory measurements and various results presented in the literature, respectively. It is shown that the procedure transforms the mixing coefficients to mass fractions yielding an accuracy comparable to carefully calibrated laboratory measurements without additional knowledge. For our laboratory measurements, the square root of the mean squared error is less than 4.82 wt%. In addition, the method corrects for systematic effects

Field Measured Spectral Albedo-Four Years of Data from the Western U.S. Prairie

NASA Astrophysics Data System (ADS)

Michalsky, Joseph J.; Hodges, Gary B.

2013-01-01

This paper presents an initial look at four years of spectral measurements used to calculate albedo for the Colorado prairie just east of the Rocky Mountain range foothills. Some issues associated with calculating broadband albedo from thermopile sensors are discussed demonstrating that uncorrected instrument issues have led to incorrect conclusions. Normalized Difference Vegetative Index (NDVI) is defined for the spectral instruments in this study and used to demonstrate the dramatic changes that can be monitored with this very sensitive product. Examples of albedo wavelength and solar-zenith angle dependence for different stages of vegetative growth and senescence are presented. The spectral albedo of fresh snow and its spectral and solar-zenith angle dependence are discussed and contrasted with other studies of these dependencies. We conclude that fresh snow is consistent with a Lambertian reflector over the solar incidence angles measured; this is contrary to most snow albedo results. Even a slope of a degree or two in the viewed surface can explain the asymmetry in the morning and afternoon albedos for snow and vegetation. Plans for extending these spectral measurements for albedo to longer wavelengths and to additional sites are described.

Quantitative filter technique measurements of spectral light absorption by aquatic particles using a portable integrating cavity absorption meter (QFT-ICAM).

PubMed

Röttgers, Rüdiger; Doxaran, David; Dupouy, Cecile

2016-01-25

The accurate determination of light absorption coefficients of particles in water, especially in very oligotrophic oceanic areas, is still a challenging task. Concentrating aquatic particles on a glass fiber filter and using the Quantitative Filter Technique (QFT) is a common practice. Its routine application is limited by the necessary use of high performance spectrophotometers, distinct problems induced by the strong scattering of the filters and artifacts induced by freezing and storing samples. Measurements of the sample inside a large integrating sphere reduce scattering effects and direct field measurements avoid artifacts due to sample preservation. A small, portable, Integrating Cavity Absorption Meter setup (QFT-ICAM) is presented, that allows rapid measurements of a sample filter. The measurement technique takes into account artifacts due to chlorophyll-a fluorescence. The QFT-ICAM is shown to be highly comparable to similar measurements in laboratory spectrophotometers, in terms of accuracy, precision, and path length amplification effects. No spectral artifacts were observed when compared to measurement of samples in suspension, whereas freezing and storing of sample filters induced small losses of water-soluble pigments (probably phycoerythrins). Remaining problems in determining the particulate absorption coefficient with the QFT-ICAM are strong sample-to-sample variations of the path length amplification, as well as fluorescence by pigments that is emitted in a different spectral region than that of chlorophyll-a.

Spectral Measurements of Geosynchronous Satellites During Glint Season

DTIC Science & Technology

2015-01-01

the satellite solar panels and has been observed in the past using broadband photometry techniques. In this paper, we present the first observations... photometry . We believe that these small-scale features can be exploited to discern satellite features such as solar panel orientation and secondary...Spectral Measurements of Geosynchronous Satellites During Glint Season Ryan M. Tucker, Evan M. Weld, Francis K. Chun, and Roger D. Tippets

Potential of optical spectral transmission measurements for joint inflammation measurements in rheumatoid arthritis patients

NASA Astrophysics Data System (ADS)

Meier, A. J. Louise; Rensen, Wouter H. J.; de Bokx, Pieter K.; de Nijs, Ron N. J.

2012-08-01

Frequent monitoring of rheumatoid arthritis (RA) patients enables timely treatment adjustments and improved outcomes. Currently this is not feasible due to a shortage of rheumatologists. An optical spectral transmission device is presented for objective assessment of joint inflammation in RA patients, while improving diagnostic accuracy and clinical workflow. A cross-sectional, nonrandomized observational study was performed with this device. In the study, 77 proximal interphalangeal (PIP) joints in 67 patients have been analyzed. Inflammation of these PIP joints was also assessed by a rheumatologist with a score varying from 1 (not inflamed) to 5 (severely inflamed). Out of 77 measurements, 27 were performed in moderate to strongly inflamed PIP joints. Comparison between the clinical assessment and an optical measurement showed a correlation coefficient r=0.63, p<0.001, 95% CI [0.47, 0.75], and a ROC curve (AUC=0.88) that shows a relative good specificity and sensitivity. Optical spectral transmission measurements in a single joint correlate with clinical assessment of joint inflammation, and therefore might be useful in monitoring joint inflammation in RA patients.

[Measurement and comparison of the spectral transmittance of cerinate porcelain and human enamel].

PubMed

Chen, Ji-Hua; Zhou, Guo-Feng; Wei, Zhang-Rui; Wang, Hui; Zhao, San-Jun

2006-12-01

To measure the spectral transmittance of Cerinate porcelain veneer and enamel in different color and different thickness. Samples of Cerinate porcelain veneers were prepared in different thickness (0.50 mm, 0.75 mm, 1.00 mm) and different Vita shade (A1, A2, A3). Enamel samples in shade A2 were made with three thickness (0.50 mm, 0.75 mm, 1.00 mm). A spectrophotometer with spectra range (380-800 nm) was employed to measure the spectral transmittance. Spectral transmittance decreased with the increasing in the thickness of specimens and decreasing in the color darkness. The transmittance of Cerinate porcelain veneer material and enamel in the same color and same thickness hadn't significant difference. The key factor to spectral transmittance of porcelain veneer materials is veneer's thickness, and the color of the materials has also some influence on it. Cerinate porcelain veneers can properly recover the transparency of teeth.

Report on the CCT Supplementary Comparison S1 of Infrared Spectral Normal Emittance/Emissivity

PubMed Central

Hanssen, Leonard; Wilthan, B.; Monte, Christian; Hollandt, Jörg; Hameury, Jacques; Filtz, Jean-Remy; Girard, Ferruccio; Battuello, Mauro; Ishii, Juntaro

2016-01-01

The National Measurement Institutes (NMIs) of the United States, Germany, France, Italy and Japan, have joined in an inter-laboratory comparison of their infrared spectral emittance scales. This action is part of a series of supplementary inter-laboratory comparisons (including thermal conductivity and thermal diffusivity) sponsored by the Consultative Committee on Thermometry (CCT) Task Group on Thermophysical Quantities (TG-ThQ). The objective of this collaborative work is to strengthen the major operative National Measurement Institutes’ infrared spectral emittance scales and consequently the consistency of radiative properties measurements carried out worldwide. The comparison has been performed over a spectral range of 2 μm to 14 μm, and a temperature range from 23 °C to 800 °C. Artefacts included in the comparison are potential standards: oxidized inconel, boron nitride, and silicon carbide. The measurement instrumentation and techniques used for emittance scales are unique for each NMI, including the temperature ranges covered as well as the artefact sizes required. For example, all three common types of spectral instruments are represented: dispersive grating monochromator, Fourier transform and filter-based spectrometers. More than 2000 data points (combinations of material, wavelength and temperature) were compared. Ninety-eight percent (98%) of the data points were in agreement, with differences to weighted mean values less than the expanded uncertainties calculated from the individual NMI uncertainties and uncertainties related to the comparison process. PMID:28239193

Spectral Variability of Oil Slicks under Different Observing Conditions: Examples from Satellite and Airborne Measurement

NASA Astrophysics Data System (ADS)

Sun, S.; Hu, C.

2017-12-01

Optical remote sensing is one of the most commonly used techniques in detecting oil in the surface ocean. This is because that oil has different optical properties from the surrounding oil-free water and oil can also modulate surface waves, thus providing a spatial contrast to facilitate delineating the oil-water boundary. Estimating oil volume or thickness from the delineated oil footprint, on the other hand, is much more difficult and currently represents a major challenge in remote sensing of oil spills. Several studies have attempted to associate reflectance spectra (magnitude and spectral shape) with oil thickness from experiments under controlled conditions, where such established relationships were used to quantify oil thickness. However, it is unclear whether or how these experiment derived relationships could be used in the real environment. Here, oil pixel spectra were extracted from several satellite sensors including Landsat, MERIS, MODIS and MISR together with airborne sensor AVIRIS that captured during the Deepwater Horizon oil spill in 2010. Same day imagery of these sensors were co-registered to compare spectra difference of oil under different observing conditions. Combining those resulted spectra with laboratory-measured oil spectra in previous study, oil's diverse spectral magnitudes and shapes were presented. Besides oil thickness, we concluded several other potential factors that may contribute significantly to the spectral response of oil slicks in the marine environment, which include sun glint strength, oil emulsification state, optical properties of oil covered water and remote sensing imagery's spatial resolution as well. And future perspectives for more accurate estimation of oil thickness are proposed.

Real-time high-resolution heterodyne-based measurements of spectral dynamics in fibre lasers

PubMed Central

Sugavanam, Srikanth; Fabbri, Simon; Le, Son Thai; Lobach, Ivan; Kablukov, Sergey; Khorev, Serge; Churkin, Dmitry

2016-01-01

Conventional tools for measurement of laser spectra (e.g. optical spectrum analysers) capture data averaged over a considerable time period. However, the generation spectrum of many laser types may involve spectral dynamics whose relatively fast time scale is determined by their cavity round trip period, calling for instrumentation featuring both high temporal and spectral resolution. Such real-time spectral characterisation becomes particularly challenging if the laser pulses are long, or they have continuous or quasi-continuous wave radiation components. Here we combine optical heterodyning with a technique of spatio-temporal intensity measurements that allows the characterisation of such complex sources. Fast, round-trip-resolved spectral dynamics of cavity-based systems in real-time are obtained, with temporal resolution of one cavity round trip and frequency resolution defined by its inverse (85 ns and 24 MHz respectively are demonstrated). We also show how under certain conditions for quasi-continuous wave sources, the spectral resolution could be further increased by a factor of 100 by direct extraction of phase information from the heterodyned dynamics or by using double time scales within the spectrogram approach. PMID:26984634

Absolute spectral response measurements of different photodiodes useful for applications in the UV spectral region

NASA Astrophysics Data System (ADS)

Pelizzo, Maria G.; Ceccherini, Paolo; Garoli, Denis; Masut, Pietro; Nicolosi, Piergiorgio

2004-09-01

Long UV radiation exposure can result in damages of biological tissues, as burns, skin aging, erythema and even melanoma cancer. In the past years an increase of melanoma cancer has been observed and associated to the atmospheric ozone deployment. Attendance of sun tanning unit centers has become a huge social phenomena, and the maximum UV radiation dose that a human being can receive is regulated by law. On the other side, UV radiation is largely used for therapeutic and germicidal purposes. In all these areas, spectroradiometer and radiomenter are needed for monitoring UVA (315-400 nm), UVB (280-315 nm) and UVC (100-280 nm) irradiance. We have selected some commercial photodiodes which can be used as solid state detectors in these instruments. We have characterized them by measuring their absolute spectral response in the 200 - 400 nm spectral range.

The absorption budget of fresh biomass burning aerosol from realistic laboratory fires

NASA Astrophysics Data System (ADS)

Wagner, N. L.; Adler, G. A.; Franchin, A.; Lamb, K.; Manfred, K.; Middlebrook, A. M.; Selimovic, V.; Schwarz, J. P.; Washenfelder, R. A.; Womack, C.; Yokelson, R. J.

2017-12-01

Wildfires are expected to increase globally due to climate change. The smoke from these wildfires has a highly uncertain radiative effect, largely due to the lack of detailed understanding of its optical properties. As part of the NOAA FIREX project, we have measured the optical properties of smoke primarily from laboratory burning of North American fuels at the Missoula Fire Sciences Laboratory. Here, we present a budget of the aerosol absorption from a portion of the laboratory fires. The total aerosol absorption was measured with photoacoustic spectrometers (PAS) at four wavelengths (405 nm, 532 nm, 660 nm, 870 nm) spanning the visible spectral region. The aerosol absorption is attributed to black carbon which absorbs broadly across the visible and ultraviolet (UV) spectral region and brown carbon (BrC) which absorbs in the blue and UV spectral regions. Then aerosol absorption measurements are compared with measurements of refractory black carbon (rBC) concentration by laser induced incandescence (SP2) and measurements of BrC concentration from a particle-into-liquid sampler coupled to a liquid absorption cell (BrC-PILS). Periodically, a thermodenuder was inserted upstream of all of the instruments to constrain the relationship between aerosol volatility and absorption. We synthesize these measurements to constrain the various contributors to total absorption including effects of lensing on rBC absorption, and of BrC that is not volatilized in the thermodenuder.

Calibration of the Multi-Spectral Solar Telescope Array multilayer mirrors and XUV filters

NASA Technical Reports Server (NTRS)

Allen, Maxwell J.; Willis, Thomas D.; Kankelborg, Charles C.; O'Neal, Ray H.; Martinez-Galarce, Dennis S.; Deforest, Craig E.; Jackson, Lisa; Lindblom, Joakim; Walker, Arthur B. C., Jr.; Barbee, Troy W., Jr.

1993-01-01

The Multi-Spectral Solar Telescope Array (MSSTA), a rocket-borne solar observatory, was successfully flown in May, 1991, obtaining solar images in eight XUV and FUV bands with 12 compact multilayer telescopes. Extensive measurements have recently been carried out on the multilayer telescopes and thin film filters at the Stanford Synchrotron Radiation Laboratory. These measurements are the first high spectral resolution calibrations of the MSSTA instruments. Previous measurements and/or calculations of telescope throughputs have been confirmed with greater accuracy. Results are presented on Mo/Si multilayer bandpass changes with time and experimental potassium bromide and tellurium filters.

Comparative Analysis of Mass Spectral Similarity Measures on Peak Alignment for Comprehensive Two-Dimensional Gas Chromatography Mass Spectrometry

PubMed Central

2013-01-01

Peak alignment is a critical procedure in mass spectrometry-based biomarker discovery in metabolomics. One of peak alignment approaches to comprehensive two-dimensional gas chromatography mass spectrometry (GC×GC-MS) data is peak matching-based alignment. A key to the peak matching-based alignment is the calculation of mass spectral similarity scores. Various mass spectral similarity measures have been developed mainly for compound identification, but the effect of these spectral similarity measures on the performance of peak matching-based alignment still remains unknown. Therefore, we selected five mass spectral similarity measures, cosine correlation, Pearson's correlation, Spearman's correlation, partial correlation, and part correlation, and examined their effects on peak alignment using two sets of experimental GC×GC-MS data. The results show that the spectral similarity measure does not affect the alignment accuracy significantly in analysis of data from less complex samples, while the partial correlation performs much better than other spectral similarity measures when analyzing experimental data acquired from complex biological samples. PMID:24151524

Spectral measurements of cosmic gamma-ray bursts with the Konus-Wind and Konus-A instruments

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

Golenetskii, S. V.; Aptekar, R. L.; Frederiks, D. D.

1998-05-16

The Konus gamma-ray burst instrumentation on board the US GGS-Wind spacecraft and the near-Earth Russian satellite Kosmos-2326 makes it possible to make spectral measurements and comparisons between 12 keV to 10 MeV. Since November 1994, over 370 bursts have been observed in the triggered mode, for which detailed spectral measurements are available. Incident photon spectra are derived from the count rate spectra of a number of bright bursts for which the celestial source position or the angle relative to the sensor axis is known. The spectral evolution of these bursts and the possible existence of spectral features in both themore » soft and hard energy bands are discussed.« less

GOSAT and OCO-2 Inter-comparison on Measured Spectral Radiance and Retrieved Carbon Dioxide

NASA Astrophysics Data System (ADS)

Kataoka, F.; Kuze, A.; Shiomi, K.; Suto, H.; Crisp, D.; Bruegge, C. J.; Schwandner, F. M.

2016-12-01

TANSO-FTS onboard GOSAT and grating spectrometer on OCO-2 use different measurement techniques to measure carbon dioxide (CO2) and molecular oxygen (O2). Both instruments observe sunlight reflected from the Earth's surface in almost the same spectral range. As a first step in cross calibrating these two instruments, we compared spectral radiance observations within the three short wave infrared (SWIR) spectral bands centered on the O2 A-band (O2A), the weak CO2 band near 1.6 microns (Weak-CO2) and 2.06 micons (Strong-CO2) bands at temporally coincident and spatially collocated points. In this work, we reconciled the different size of the footprints and evaluated at various types of surface targets such as ocean, desert and forest. For radiometric inter-comparisons, we consider long term instrument sensitivity degradation in orbit and differences in viewing geometry and associated differences in surface bidirectional reflectance distribution function (BRDF). Measured spectral radiances agree very well within 5% for all bands. This presentation will summarize these comparisons of GOSAT and OCO-2 spectral radiance observations and associated estimates of carbon dioxide and related parameters retrieved with the same algorithm at matchup points. We will also discuss instrument related uncertainties from various target observations.

In-Flight Spectral Calibration of the APEX Imaging Spectrometer Using Fraunhofer Lines

NASA Astrophysics Data System (ADS)

Kuhlmann, Gerrit; Hueni, Andreas; Damm, Aalexander; Brunner, Dominik

2015-11-01

The Airborne Prism EXperiment (APEX) is an imaging spectrometer which allows to observe atmospheric trace gases such as nitrogen dioxide (NO2). Using a high resolution spectrum of solar Fraunhofer lines, APEX measurements collected during flight have been spectrally calibrated for centre wavelength positions (CW) and instrument slit function (ISF) and compared to the laboratory calibration. We find that CWs depend strongly on both across- and along-track position due to spectral smile and CWs dependency on ambient pressure. The width of the ISF is larger than estimated from the laboratory calibration but can be described by a linear scaling of the laboratory values. The ISF width depends on across- but not on along-track direction. The results demonstrate the importance of characterizing and monitoring the instrument performance during flight and will be used to improve the Empa APEX NO2 retrieval algorithm.

PILOT STUDY: Report on the CCPR Pilot Comparison: Spectral Responsivity 10 nm to 20 nm

NASA Astrophysics Data System (ADS)

Scholze, Frank; Vest, Robert; Saito, Terubumi

2010-01-01

The CCPR Pilot Comparison on spectral responsivity in the 10 nm to 20 nm spectral range was carried out within the framework of the CIPM Mutual Recognition Arrangement by three laboratories: PTB (Germany), NIST (USA), and NMIJ/AIST (Japan) with PTB acting as the central and reporting laboratory. All participating laboratories used monochromatized synchrotron radiation. PTB and NIST used a cryogenic radiometer as the primary standard detector and NMIJ, an ionization chamber with extrapolation by a wavelength-independent detector. The aim of the pilot comparison was to check the accuracy of the radiometric scale of spectral responsivity in the short wavelength EUV spectral range which has recently gained in technological importance. The wavelengths of measurement were from 11.5 nm to 20 nm in 0.5 nm steps and additionally 12.2 nm. The comparison was carried out through the calibration of a group of transfer standard detectors. Two sets of three diodes of types AXUV and SXUV from International Radiation Detectors, Inc. were used for the comparison. The comparison had the form of a star comparison: Pilot-lab A-pilot-lab B-pilot, PTB acting as the pilot laboratory. All results were communicated directly to the pilot laboratory. The report describes in detail the measurements made at PTB and summarizes the reports submitted by the participants. Measurements carried out by the pilot laboratory before and after the circulation of the detectors proved that the stability of the detectors was sufficient for the comparison. For the type AXUV detectors, however, changes in their responsivity contributed to the uncertainty of the comparison. Measurement results from participants and their associated uncertainties were analyzed in this report according to the Guidelines for CCPR Comparison Report Preparation. The uncertainty contributions were separated, as to whether they are wavelength dependent or not. All bilateral DoE are well within the respective k = 2 expanded uncertainty

High-resolution Laboratory Measurements of Coronal Lines near the Fe IX Line at 171 Å

NASA Astrophysics Data System (ADS)

Beiersdorfer, Peter; Träbert, Elmar

2018-02-01

We present high-resolution laboratory measurements in the spectral region between 165 and 175 Å that focus on the emission from various ions of C, O, F, Ne, S, Ar, Fe, and Ni. This wavelength region is centered on the λ171 Fe IX channel of the Atmospheric Imaging Assembly on the Solar Dynamics Observatory, and we place special emphasis on the weaker emission lines of Fe IX predicted in this region. In general, our measurements show a multitude of weak lines missing in the current databases, where the emission lines of Ni are probably most in need of further identification and reclassification. We also find that the wavelengths of some of the known lines need updating. Using the multi-reference Møller–Plesset method for wavelength predictions and collisional-radiative modeling of the line intensities, we have made tentative assignments of more than a dozen lines to the spectrum of Fe IX, some of which have formerly been identified as Fe VII, Fe XIV, or Fe XVI lines. Several Fe features remain unassigned, although they appear to be either Fe VII or Fe X lines. Further work will be needed to complete and correct the spectral line lists in this wavelength region.

[A Terahertz Spectral Database Based on Browser/Server Technique].

PubMed

Zhang, Zhuo-yong; Song, Yue

2015-09-01

With the solution of key scientific and technical problems and development of instrumentation, the application of terahertz technology in various fields has been paid more and more attention. Owing to the unique characteristic advantages, terahertz technology has been showing a broad future in the fields of fast, non-damaging detections, as well as many other fields. Terahertz technology combined with other complementary methods can be used to cope with many difficult practical problems which could not be solved before. One of the critical points for further development of practical terahertz detection methods depends on a good and reliable terahertz spectral database. We developed a BS (browser/server) -based terahertz spectral database recently. We designed the main structure and main functions to fulfill practical requirements. The terahertz spectral database now includes more than 240 items, and the spectral information was collected based on three sources: (1) collection and citation from some other abroad terahertz spectral databases; (2) collected from published literatures; and (3) spectral data measured in our laboratory. The present paper introduced the basic structure and fundament functions of the terahertz spectral database developed in our laboratory. One of the key functions of this THz database is calculation of optical parameters. Some optical parameters including absorption coefficient, refractive index, etc. can be calculated based on the input THz time domain spectra. The other main functions and searching methods of the browser/server-based terahertz spectral database have been discussed. The database search system can provide users convenient functions including user registration, inquiry, displaying spectral figures and molecular structures, spectral matching, etc. The THz database system provides an on-line searching function for registered users. Registered users can compare the input THz spectrum with the spectra of database, according to

A standard for measuring metadata quality in spectral libraries

NASA Astrophysics Data System (ADS)

Rasaiah, B.; Jones, S. D.; Bellman, C.

2013-12-01

A standard for measuring metadata quality in spectral libraries Barbara Rasaiah, Simon Jones, Chris Bellman RMIT University Melbourne, Australia barbara.rasaiah@rmit.edu.au, simon.jones@rmit.edu.au, chris.bellman@rmit.edu.au ABSTRACT There is an urgent need within the international remote sensing community to establish a metadata standard for field spectroscopy that ensures high quality, interoperable metadata sets that can be archived and shared efficiently within Earth observation data sharing systems. Metadata are an important component in the cataloguing and analysis of in situ spectroscopy datasets because of their central role in identifying and quantifying the quality and reliability of spectral data and the products derived from them. This paper presents approaches to measuring metadata completeness and quality in spectral libraries to determine reliability, interoperability, and re-useability of a dataset. Explored are quality parameters that meet the unique requirements of in situ spectroscopy datasets, across many campaigns. Examined are the challenges presented by ensuring that data creators, owners, and data users ensure a high level of data integrity throughout the lifecycle of a dataset. Issues such as field measurement methods, instrument calibration, and data representativeness are investigated. The proposed metadata standard incorporates expert recommendations that include metadata protocols critical to all campaigns, and those that are restricted to campaigns for specific target measurements. The implication of semantics and syntax for a robust and flexible metadata standard are also considered. Approaches towards an operational and logistically viable implementation of a quality standard are discussed. This paper also proposes a way forward for adapting and enhancing current geospatial metadata standards to the unique requirements of field spectroscopy metadata quality. [0430] BIOGEOSCIENCES / Computational methods and data processing [0480

Purdue Rare Isotope Measurement Laboratory

NASA Astrophysics Data System (ADS)

Caffee, M.; Elmore, D.; Granger, D.; Muzikar, P.

2002-12-01

The Purdue Rare Isotope Measurement Laboratory (PRIME Lab) is a dedicated research and service facility for accelerator mass spectrometry. AMS is an ultra-sensitive analytical technique used to measure low levels of long-lived cosmic-ray-produced and anthropogenic radionuclides, and rare trace elements. We measure 10Be (T1/2 = 1.5 My), 26Al (.702 My), 36Cl (.301 My), and 129I (16 My), in geologic samples. Applications include dating the cosmic-ray-exposure time of rocks on Earth's surface, determining rock and sediment burial ages, measuring the erosion rates of rocks and soils, and tracing and dating ground water. We perform sample preparation and separation chemistries for these radio-nuclides for our internal research activities and for those external researchers not possessing this capability. Our chemical preparation laboratories also serve as training sites for members of the geoscience community developing these techniques at their institutions. Research at Purdue involves collaborators among members of the Purdue Departments of Physics, Earth and Atmospheric Sciences, Chemistry, Agronomy, and Anthropology. We also collaborate and serve numerous scientists from other institutions. We are currently in the process of modernizing the facility with the goals of higher precision for routinely measured radio-nuclides, increased sample throughput, and the development of new measurement capabilities for the geoscience community.

Spectral density measurements of gyro noise

NASA Technical Reports Server (NTRS)

Truncale, A.; Koenigsberg, W.; Harris, R.

1972-01-01

Power spectral density (PSD) was used to analyze the outputs of several gyros in the frequency range from 0.01 to 200 Hz. Data were accumulated on eight inertial quality instruments. The results are described in terms of input angle noise (arcsec 2/Hz) and are presented on log-log plots of PSD. These data show that the standard deviation of measurement noise was 0.01 arcsec or less for some gyros in the passband from 1 Hz down 10 0.01 Hz and probably down to 0.001 Hz for at least one gyro. For the passband between 1 and 100 Hz, uncertainties in the 0.01 and 0.05 arcsec region were observed.

Development of a Cone Penetrometer for Measuring Spectral Characteristics of Soils in Situ

NASA Technical Reports Server (NTRS)

Lee, Landris T., Jr.; Malone, Philip G.

1993-01-01

A patent was recently granted to the U.S. Army for an adaptation of a soil cone penetrometer that can be used to measure the spectral characteristics (fluorescence or reflectance) of soils adjacent to the penetrometer rod. The system can use a variety of light sources and spectral analytical equipment. A laser induced fluorescence measuring system has proven to be of immediate use in mapping the distribution of oil contaminated soil at waste disposal and oil storage areas. The fiber optic adaptation coupled with a cone penetrometer permits optical characteristics of the in-situ soil to be measured rapidly, safely, and inexpensively. The fiber optic cone penetrometer can be used to gather spectral data to a depth of approximately 25 to 30 m even in dense sands or stiff clays and can investigate 300 m of soil per day. Typical detection limits for oil contamination in sand is on the order of several hundred parts per million.

Preliminary measurements of spectral signatures of tropical and temperate plants in the thermal infrared

NASA Technical Reports Server (NTRS)

Salisbury, John W.; Milton, N. M.

1987-01-01

Spectral reflectance measurements of seven tropical species and six deciduous species were carried out in thermal infrared to establish the species-dependent spectral characteristics and to investigate the effect on spectral signatures of environmental variables, such as leaf maturity, drought, and metal stress. Seasonal variations of spectral signatures occurred between spring and summer leaves, but such variations were minimal during summer and early fall. Overall reflectance of senescent leaves was higher than that of young leaves, as was the reflectance of leaves from trees growing in metal-enriched soils, as compared with leaves from the control area. However, the characteristic spectral features were not changed in either case. It was also found that water stress did not have any effect on the infrared signatures: trees grown during a drought season maintained their characteristic spectral signatures.

Near-infrared spectral methods for noninvasively measuring blood glucose

NASA Astrophysics Data System (ADS)

Fei, Sun; Kong, Deyi; Mei, Tao; Tao, Yongchun

2004-05-01

Determination of blood glucose concentrations in diabetic patients is a frequently occurring procedure and an important tool for diabetes management. Use of noninvasive detection techniques can relieve patients from the pain of frequent finger pokes and avoid the infection of disease via blood. This thesis discusses current research and analyzes the advantages and shortages of different measurement methods, including: optical methods (Transmission, Polarimetry and scattering), then, we give emphasis to analyze the technology of near-infrared (NIR) spectra. NIR spectral range 700 nm ~2300 nm was used because of its good transparency for biological tissue and presence of glucose absorption band. In this work, we present an outline of noninvasive blood glucose measurement. A near-infrared light beam is passed through the finger, and the spectral components of the emergent beam are measured using spectroscopic techniques. The device includes light sources having the wavelengths of 600 nm - 1800 nm to illuminate the tissue. Receptors associated with the light sources for receiving light and generating a transmission signal representing the light transmitted are also provided. Once a transmission signal is received by receptors, and the high and low values from each of the signals are stored in the device. The averaged values are then analyzed to determine the glucose concentration, which is displayed on the device.

Interstellar PAH Analogs in the Laboratory: Comparison with Astronomical Data

NASA Technical Reports Server (NTRS)

Salama, Farid

2005-01-01

Polycyclic Aromatic Hydrocarbons (PAHs) are an important and ubiquitous component of carbon-bearing materials in space. PAHs are the best-known candidates to account for the IR emission bands (UIR bands) and PAH spectral features are now being used as new probes of the ISM. PAHs are also thought to be among the carriers of the diffuse interstellar absorption bands (DIBs). In the model dealing with the interstellar spectral features, PAHs are present as a mixture of radicals, ions and neutral species. PAH ionization states reflect the ionization balance of the medium while PAH size, composition, and structure reflect the energetic and chemical history of the medium. A major challenge for laboratory astrophysics is to reproduce (in a realistic way) the physical conditions that exist in the emission and/or absorption interstellar zones. An extensive laboratory program has been developed at NASA Ames to assess the physical and chemical properties of PAHs in such environments and to describe how they influence the radiation and energy balance in space and the interstellar chemistry. In particular, laboratory experiments provide measurements of the spectral characteristics of interstellar PAH analogs from the ultraviolet and visible range to the infrared range for comparison with astronomical data. This paper will focus on the recent progress made in the laboratory to measure the direct absorption spectra of neutral and ionized PAHs in the near-UV and visible range. Intrinsic band profiles and band positions of cold gas-phase PAHs can now be measured with high-sensitivity spectroscopy and directly compared to the astronomical data. Preliminary conclusions from the comparison of the laboratory data with astronomical observations will also be presented.

Discrimination of fungal infections on grape berries via spectral signatures

NASA Astrophysics Data System (ADS)

Molitor, Daniel; Griesser, Michaela; Schütz, Erich; Khuen, Marie-Therese; Schefbeck, Christa; Ronellenfitsch, Franz Kai; Schlerf, Martin; Beyer, Marco; Schoedl-Hummel, Katharina; Anhalt, Ulrike; Forneck, Astrid

2016-04-01

The fungal pathogens Botrytis cinerea and Penicillium expansum are causing economic damages on grapevine worldwide. Especially the simultaneous occurrence of both often results in off-flavours highly threatening wine quality. For the classification of grape quality as well as for the determination of targeted enological treatments, the knowledge of the level of fungal attack is of highest interest. However, visual assessment and pathogen discrimination are cost-intensive. Consequently, a pilot laboratory study aimed at (i) detecting differences in spectral signatures between grape berry lots with different levels of infected berries (B. cinerea and/or P. expansum) and (ii) detecting links between spectral signatures and biochemical as well as quantitative molecular markers for fungal attack. To this end, defined percentages (infection levels) of table grape berries were inoculated with fungal spore suspensions. Spectral measurements were taken using a FieldSpec 3 Max spectroradiometer (ASD Inc., Boulder/Colorado, USA) in regular intervals after inoculation. In addition, fungal attack was determined enzymatically) and quantitatively (real-time PCR). In addition, gluconic acid concentrations (as a potential markers for fungal attack) were determined photometrically. Results indicate that based on spectral signatures, a discrimination of P. expansum and B. cinerea infections as well as of different B. cinerea infection levels is possible. Real-time PCR analyses, detecting DNA levels of both fungi, showed yet a low detection level. Whereas the gluconic acid concentrations turned out to be specific for the two fungi tested (B. cinerea vs. P. expansum) and thus may serve as a differentiating biochemical marker. Correlation analyses between spectral measurements and biological data (gluconic acid concentrations, fungi DNA) as well as further common field and laboratory trials are targeted.

Clinical measurements analysis of multi-spectral photoplethysmograph biosensors

NASA Astrophysics Data System (ADS)

Asare, Lasma; Kviesis-Kipge, Edgars; Spigulis, Janis

2014-05-01

The developed portable multi-spectral photoplethysmograph (MS-PPG) optical biosensor device, intended for analysis of peripheral blood volume pulsations at different vascular depths, has been clinically verified. Multi-spectral monitoring was performed by means of a four - wavelengths (454 nm, 519 nm, 632 nm and 888 nm) light emitted diodes and photodiode with multi-channel signal output processing. Two such sensors can be operated in parallel and imposed on the patient's skin. The clinical measurements confirmed ability to detect PPG signals at four wavelengths simultaneously and to record temporal differences in the signal shapes (corresponding to different penetration depths) in normal and pathological skin. This study analyzed wavelengths relations between systole and diastole peak difference at various tissue depths in normal and pathological skin. The difference between parameters of healthy and pathological skin at various skin depths could be explain by oxy- and deoxyhemoglobin dominance at different wavelengths operated in sensor. The proposed methodology and potential clinical applications in dermatology for skin assessment are discussed.

The Multi-Spectral Solar Telescope Array. II - Soft X-ray/EUV reflectivity of the multilayer mirrors

NASA Technical Reports Server (NTRS)

Barbee, Troy W., Jr.; Weed, J. W.; Hoover, Richard B. C., Jr.; Allen, Max J.; Lindblom, Joakim F.; O'Neal, Ray H.; Kankelborg, Charles C.; Deforest, Craig E.; Paris, Elizabeth S.; Walker, Arthur B. C.

1992-01-01

We have developed seven compact soft X-ray/EUV (XUV) multilayer coated and two compact FUV interference film coated Cassegrain and Ritchey-Chretien telescopes for a rocket borne observatory, the Multi-Spectral Solar Telescope Array. We report here on extensive measurements of the efficiency and spectral bandpass of the XUV telescopes carried out at the Stanford Synchrotron Radiation Laboratory.

Multivariate Analysis of Solar Spectral Irradiance Measurements

NASA Technical Reports Server (NTRS)

Pilewskie, P.; Rabbette, M.

2001-01-01

Principal component analysis is used to characterize approximately 7000 downwelling solar irradiance spectra retrieved at the Southern Great Plains site during an Atmospheric Radiation Measurement (ARM) shortwave intensive operating period. This analysis technique has proven to be very effective in reducing a large set of variables into a much smaller set of independent variables while retaining the information content. It is used to determine the minimum number of parameters necessary to characterize atmospheric spectral irradiance or the dimensionality of atmospheric variability. It was found that well over 99% of the spectral information was contained in the first six mutually orthogonal linear combinations of the observed variables (flux at various wavelengths). Rotation of the principal components was effective in separating various components by their independent physical influences. The majority of the variability in the downwelling solar irradiance (380-1000 nm) was explained by the following fundamental atmospheric parameters (in order of their importance): cloud scattering, water vapor absorption, molecular scattering, and ozone absorption. In contrast to what has been proposed as a resolution to a clear-sky absorption anomaly, no unexpected gaseous absorption signature was found in any of the significant components.

Spectral Archives: Extending Spectral Libraries to Analyze both Identified and Unidentified Spectra

PubMed Central

Frank, Ari M.; Monroe, Matthew E.; Shah, Anuj R.; Carver, Jeremy J.; Bandeira, Nuno F.; Moore, Ronald J.; Anderson, Gordon A.; Smith, Richard D.; Pevzner, Pavel A.

2011-01-01

MS/MS experiments generate multiple, nearly identical spectra of the same peptide in various laboratories, but proteomics researchers typically do not leverage the unidentified spectra produced in other labs to decode spectra generated in their own labs. We propose a spectral archives approach that clusters MS/MS datasets, representing similar spectra by a single consensus spectrum. Spectral archives extend spectral libraries by analyzing both identified and unidentified spectra in the same way and maintaining information about spectra of peptides shared across species and conditions. Thus archives offer both traditional library spectrum similarity-based search capabilities along with novel ways to analyze the data. By developing a clustering tool, MS-Cluster, we generated a spectral archive from ~1.18 billion spectra that greatly exceeds the size of existing spectral repositories. We advocate that publicly available data should be organized into spectral archives, rather than be analyzed as disparate datasets, as is mostly the case today. PMID:21572408

Algorithmic Foundation of Spectral Rarefaction for Measuring Satellite Imagery Heterogeneity at Multiple Spatial Scales

PubMed Central

Rocchini, Duccio

2009-01-01

Measuring heterogeneity in satellite imagery is an important task to deal with. Most measures of spectral diversity have been based on Shannon Information theory. However, this approach does not inherently address different scales, ranging from local (hereafter referred to alpha diversity) to global scales (gamma diversity). The aim of this paper is to propose a method for measuring spectral heterogeneity at multiple scales based on rarefaction curves. An algorithmic solution of rarefaction applied to image pixel values (Digital Numbers, DNs) is provided and discussed. PMID:22389600

Spectral Discrete Probability Density Function of Measured Wind Turbine Noise in the Far Field

PubMed Central

Ashtiani, Payam; Denison, Adelaide

2015-01-01

Of interest is the spectral character of wind turbine noise at typical residential set-back distances. In this paper, a spectral statistical analysis has been applied to immission measurements conducted at three locations. This method provides discrete probability density functions for the Turbine ONLY component of the measured noise. This analysis is completed for one-third octave sound levels, at integer wind speeds, and is compared to existing metrics for measuring acoustic comfort as well as previous discussions on low-frequency noise sources. PMID:25905097

Establishing a method to measure bone structure using spectral CT

NASA Astrophysics Data System (ADS)

Ramyar, M.; Leary, C.; Raja, A.; Butler, A. P. H.; Woodfield, T. B. F.; Anderson, N. G.

2017-03-01

Combining bone structure and density measurement in 3D is required to assess site-specific fracture risk. Spectral molecular imaging can measure bone structure in relation to bone density by measuring macro and microstructure of bone in 3D. This study aimed to optimize spectral CT methodology to measure bone structure in excised bone samples. MARS CT with CdTe Medipix3RX detector was used in multiple energy bins to calibrate bone structure measurements. To calibrate thickness measurement, eight different thicknesses of Aluminium (Al) sheets were scanned one in air and the other around a falcon tube and then analysed. To test if trabecular thickness measurements differed depending on scan plane, a bone sample from sheep proximal tibia was scanned in two orthogonal directions. To assess the effect of air on thickness measurement, two parts of the same human femoral head were scanned in two conditions (in the air and in PBS). The results showed that the MARS scanner (with 90μm voxel size) is able to accurately measure the Al (in air) thicknesses over 200μm but it underestimates the thicknesses below 200μm because of partial volume effect in Al-air interface. The Al thickness measured in the highest energy bin is overestimated at Al-falcon tube interface. Bone scanning in two orthogonal directions gives the same trabecular thickness and air in the bone structure reduced measurement accuracy. We have established a bone structure assessment protocol on MARS scanner. The next step is to combine this with bone densitometry to assess bone strength.

Spectral Characterization of Analog Samples in Anticipation of OSIRIS-REx's Arrival at Bennu

NASA Technical Reports Server (NTRS)

Donaldson Hanna, K. L.; Schrader, D. L.; Bowles, N. E.; Clark, B. E.; Cloutis, E. A.; Connolly, H. C., Jr.; Hamilton, V. E.; Keller, L. P.; Lauretta, D. S.; Lim, L. F.;

Spectral BRDF-based determination of proper measurement geometries to characterize color shift of special effect coatings.

PubMed

Ferrero, Alejandro; Rabal, Ana; Campos, Joaquín; Martínez-Verdú, Francisco; Chorro, Elísabet; Perales, Esther; Pons, Alicia; Hernanz, María Luisa

2013-02-01

A reduced set of measurement geometries allows the spectral reflectance of special effect coatings to be predicted for any other geometry. A physical model based on flake-related parameters has been used to determine nonredundant measurement geometries for the complete description of the spectral bidirectional reflectance distribution function (BRDF). The analysis of experimental spectral BRDF was carried out by means of principal component analysis. From this analysis, a set of nine measurement geometries was proposed to characterize special effect coatings. It was shown that, for two different special effect coatings, these geometries provide a good prediction of their complete color shift.

Anthropometric measures in cardiovascular disease prediction: comparison of laboratory-based versus non-laboratory-based model.

PubMed

Dhana, Klodian; Ikram, M Arfan; Hofman, Albert; Franco, Oscar H; Kavousi, Maryam

2015-03-01

Body mass index (BMI) has been used to simplify cardiovascular risk prediction models by substituting total cholesterol and high-density lipoprotein cholesterol. In the elderly, the ability of BMI as a predictor of cardiovascular disease (CVD) declines. We aimed to find the most predictive anthropometric measure for CVD risk to construct a non-laboratory-based model and to compare it with the model including laboratory measurements. The study included 2675 women and 1902 men aged 55-79 years from the prospective population-based Rotterdam Study. We used Cox proportional hazard regression analysis to evaluate the association of BMI, waist circumference, waist-to-hip ratio and a body shape index (ABSI) with CVD, including coronary heart disease and stroke. The performance of the laboratory-based and non-laboratory-based models was evaluated by studying the discrimination, calibration, correlation and risk agreement. Among men, ABSI was the most informative measure associated with CVD, therefore ABSI was used to construct the non-laboratory-based model. Discrimination of the non-laboratory-based model was not different than laboratory-based model (c-statistic: 0.680-vs-0.683, p=0.71); both models were well calibrated (15.3% observed CVD risk vs 16.9% and 17.0% predicted CVD risks by the non-laboratory-based and laboratory-based models, respectively) and Spearman rank correlation and the agreement between non-laboratory-based and laboratory-based models were 0.89 and 91.7%, respectively. Among women, none of the anthropometric measures were independently associated with CVD. Among middle-aged and elderly where the ability of BMI to predict CVD declines, the non-laboratory-based model, based on ABSI, could predict CVD risk as accurately as the laboratory-based model among men. Published by the BMJ Publishing Group Limited. For permission to use (where not already granted under a licence) please go to http://group.bmj.com/group/rights-licensing/permissions.

Are resting state spectral power measures related to executive functions in healthy young adults?

PubMed

Gordon, Shirley; Todder, Doron; Deutsch, Inbal; Garbi, Dror; Getter, Nir; Meiran, Nachshon

2018-01-08

Resting-state electroencephalogram (rsEEG) has been found to be associated with psychopathology, intelligence, problem solving, academic performance and is sometimes used as a supportive physiological indicator of enhancement in cognitive training interventions (e.g. neurofeedback, working memory training). In the current study, we measured rsEEG spectral power measures (relative power, between-band ratios and asymmetry) in one hundred sixty five young adults who were also tested on a battery of executive function (EF). We specifically focused on upper Alpha, Theta and Beta frequency bands given their putative role in EF. Our indices enabled finding correlations since they had decent-to-excellent internal and retest reliability and very little range restriction relative to a nation-wide representative large sample. Nonetheless, Bayesian statistical inference indicated support for the null hypothesis concerning lack of monotonic correlation between EF and rsEEG spectral power measures. Therefore, we conclude that, contrary to the quite common interpretation, these rsEEG spectral power measures do not indicate individual differences in the measured EF abilities. Copyright © 2017 Elsevier Ltd. All rights reserved.

Phase noise measurements with a cryogenic power-splitter to minimize the cross-spectral collapse effect

NASA Astrophysics Data System (ADS)

Hati, Archita; Nelson, Craig W.; Pappas, David P.; Howe, David A.

2017-11-01

The cross-spectrum noise measurement technique enables enhanced resolution of spectral measurements. However, it has disadvantages, namely, increased complexity, inability of making real-time measurements, and bias due to the "cross-spectral collapse" (CSC) effect. The CSC can occur when the spectral density of a random process under investigation approaches the thermal noise of the power splitter. This effect can severely bias results due to a differential measurement between the investigated noise and the anti-correlated (phase-inverted) noise of the power splitter. In this paper, we report an accurate measurement of the phase noise of a thermally limited electronic oscillator operating at room temperature (300 K) without significant CSC bias. We mitigated the problem by cooling the power splitter to liquid helium temperature (4 K). We quantify errors of greater than 1 dB that occur when the thermal noise of the oscillator at room temperature is measured with the power splitter at temperatures above 77 K.

Laboratory Measurements of Cometary Photochemical Phenomena.

DTIC Science & Technology

1981-12-04

PROGFIAM ELEMENT.PROJECT TASK Laser .Chemistry Division AREA & WORK UNIT NUMaZRS Department of Chemistry - Howard University NR.051-733 Wash’ ngtQn, D. C...William M. Jackson Laser Chemistry Division Department of Chemistry Howard University .Washington, D. C. 20059 / Published by Jet Propulsion Laboratory...MEASUREMENTS OF COMETARY PHOTOCHEMICAL PHENOMENA William M. Jackson Howard University Washington, DC 20059 Abstract Laboratory experiments are described

Theory of spectral radiance of pollutants at sea, volume 1

NASA Technical Reports Server (NTRS)

1979-01-01

Remote measurement of pollutants dumped in the sea, not oil slicks, but soluble pollutants that change the color of the water, is addressed. The sensor is a spectral radiometer that flies over the polluted area and compares its spectral radiance (color) to that of surrounding clean seawater. The goal is to infer the concentration of pollutants using the measured radiance of the sea compared to laboratory measurements of reflection and transmission spectra of the pollutants. The subject is treated in three steps: (1) the quantities involved are defined and means for measuring them are described; (2) the equations for remote sensing with a low-flying aircraft are derived, in which wase the absorption and radiance of intervening air is negligible; and (3) high-flying aircraft and satellites are applied, in which case the radiance of intervening air is the major problem.

A Novel Technique Applying Spectral Estimation to Johnson Noise Thermometry

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

Ezell, N. Dianne Bull; Britton, Chuck; Ericson, Nance

Johnson noise thermometry is one of many important measurement techniques used to monitor the safety levels and stability in a nuclear reactor. However, this measurement is very dependent on the minimal electromagnetic environment. Properly removing unwanted electromagnetic interference (EMI) is critical for accurate drift-free temperature measurements. The two techniques developed by Oak Ridge National Laboratory (ORNL) to remove transient and periodic EMI are briefly discussed here. Spectral estimation is a key component in the signal processing algorithm used for EMI removal and temperature calculation. The cross-power spectral density is a key component in the Johnson noise temperature computation. Applying eithermore » technique requires the simple addition of electronics and signal processing to existing resistive thermometers. With minimal installation changes, the system discussed here can be installed on existing nuclear power plants. The Johnson noise system developed is tested at three locations: ORNL, Sandia National Laboratory, and the Tennessee Valley Authority’s Kingston Fossil Plant. Each of these locations enabled improvement on the EMI removal algorithm. Finally, the conclusions made from the results at each of these locations is discussed, as well as possible future work.« less

A Novel Technique Applying Spectral Estimation to Johnson Noise Thermometry

DOE PAGES

Ezell, N. Dianne Bull; Britton, Chuck; Ericson, Nance; ...

2018-03-30

Johnson noise thermometry is one of many important measurement techniques used to monitor the safety levels and stability in a nuclear reactor. However, this measurement is very dependent on the minimal electromagnetic environment. Properly removing unwanted electromagnetic interference (EMI) is critical for accurate drift-free temperature measurements. The two techniques developed by Oak Ridge National Laboratory (ORNL) to remove transient and periodic EMI are briefly discussed here. Spectral estimation is a key component in the signal processing algorithm used for EMI removal and temperature calculation. The cross-power spectral density is a key component in the Johnson noise temperature computation. Applying eithermore » technique requires the simple addition of electronics and signal processing to existing resistive thermometers. With minimal installation changes, the system discussed here can be installed on existing nuclear power plants. The Johnson noise system developed is tested at three locations: ORNL, Sandia National Laboratory, and the Tennessee Valley Authority’s Kingston Fossil Plant. Each of these locations enabled improvement on the EMI removal algorithm. Finally, the conclusions made from the results at each of these locations is discussed, as well as possible future work.« less

Modeling and validation of spectral BRDF on material surface of space target

NASA Astrophysics Data System (ADS)

Hou, Qingyu; Zhi, Xiyang; Zhang, Huili; Zhang, Wei

2014-11-01

The modeling and the validation methods of the spectral BRDF on the material surface of space target were presented. First, the microscopic characteristics of the space targets' material surface were analyzed based on fiber-optic spectrometer using to measure the direction reflectivity of the typical materials surface. To determine the material surface of space target is isotropic, atomic force microscopy was used to measure the material surface structure of space target and obtain Gaussian distribution model of microscopic surface element height. Then, the spectral BRDF model based on that the characteristics of the material surface were isotropic and the surface micro-facet with the Gaussian distribution which we obtained was constructed. The model characterizes smooth and rough surface well for describing the material surface of the space target appropriately. Finally, a spectral BRDF measurement platform in a laboratory was set up, which contains tungsten halogen lamp lighting system, fiber optic spectrometer detection system and measuring mechanical systems with controlling the entire experimental measurement and collecting measurement data by computers automatically. Yellow thermal control material and solar cell were measured with the spectral BRDF, which showed the relationship between the reflection angle and BRDF values at three wavelengths in 380nm, 550nm, 780nm, and the difference between theoretical model values and the measured data was evaluated by relative RMS error. Data analysis shows that the relative RMS error is less than 6%, which verified the correctness of the spectral BRDF model.

SeaWiFS technical report series. Volume 23: SeaWiFS prelaunch radiometric calibration and spectral characterization

NASA Technical Reports Server (NTRS)

Barnes, Robert A.; Holmes, Alan W.; Barnes, William L.; Esaias, Wayne E.; Mcclain, Charles R.; Svitek, Tomas; Hooker, Stanford B.; Firestone, Elaine R.; Acker, James G.

1994-01-01

Based on the operating characteristics of the Sea-viewing Wide Field-of-view Sensor (SeaWiFS), calibration equations have been developed that allow conversion of the counts from the radiometer into Earth-existing radiances. These radiances are the geophysical properties the instrument has been designed to measure. SeaWiFS uses bilinear gains to allow high sensitivity measurements of ocean-leaving radiances and low sensitivity measurements of radiances from clouds, which are much brighter than the ocean. The calculation of these bilinear gains is central to the calibration equations. Several other factors within these equations are also included. Among these are the spectral responses of the eight SeaWiFS bands. A band's spectral response includes the ability of the band to isolate a portion of the electromagnetic spectrum and the amount of light that lies outside of that region. The latter is termed out-of-band response. In the calibration procedure, some of the counts from the instrument are produced by radiance in the out-of-band region. The number of those counts for each band is a function of the spectral shape of the source. For the SeaWiFS calibration equations, the out-of-band responses are converted from those for the laboratory source into those for a source with the spectral shape of solar flux. The solar flux, unlike the laboratory calibration, approximates the spectral shape of the Earth-existing radiance from the oceans. This conversion modifies the results from the laboratory radiometric calibration by 1-4 percent, depending on the band. These and other factors in the SeaWiFS calibration equations are presented here, both for users of the SeaWiFS data set and for researchers making ground-based radiance measurements in support of Sea WiFS.

Laboratory measurements of upwelled radiance and reflectance spectra of Calvert, Ball, Jordan, and Feldspar soil sediments

NASA Technical Reports Server (NTRS)

Whitlock, C. H.; Usry, J. W.; Witte, W. G.; Gurganus, E. A.

1977-01-01

An effort to investigate the potential of remote sensing for monitoring nonpoint source pollution was conducted. Spectral reflectance characteristics for four types of soil sediments were measured for mixture concentrations between 4 and 173 ppm. For measurements at a spectral resolution of 32 mm, the spectral reflectances of Calvert, Ball, Jordan, and Feldspar soil sediments were distinctly different over the wavelength range from 400 to 980 nm at each concentration tested. At high concentrations, spectral differences between the various sediments could be detected by measurements with a spectral resolution of 160 nm. At a low concentration, only small differences were observed between the various sediments when measurements were made with 160 nm spectral resolution. Radiance levels generally varied in a nonlinear manner with sediment concentration; linearity occurred in special cases, depending on sediment type, concentration range, and wavelength.

Improving the spectral measurement accuracy based on temperature distribution and spectra-temperature relationship

NASA Astrophysics Data System (ADS)

Li, Zhe; Feng, Jinchao; Liu, Pengyu; Sun, Zhonghua; Li, Gang; Jia, Kebin

2018-05-01

Temperature is usually considered as a fluctuation in near-infrared spectral measurement. Chemometric methods were extensively studied to correct the effect of temperature variations. However, temperature can be considered as a constructive parameter that provides detailed chemical information when systematically changed during the measurement. Our group has researched the relationship between temperature-induced spectral variation (TSVC) and normalized squared temperature. In this study, we focused on the influence of temperature distribution in calibration set. Multi-temperature calibration set selection (MTCS) method was proposed to improve the prediction accuracy by considering the temperature distribution of calibration samples. Furthermore, double-temperature calibration set selection (DTCS) method was proposed based on MTCS method and the relationship between TSVC and normalized squared temperature. We compare the prediction performance of PLS models based on random sampling method and proposed methods. The results from experimental studies showed that the prediction performance was improved by using proposed methods. Therefore, MTCS method and DTCS method will be the alternative methods to improve prediction accuracy in near-infrared spectral measurement.

Bi-photon spectral correlation measurements from a silicon nanowire in the quantum and classical regimes

PubMed Central

Jizan, Iman; Helt, L. G.; Xiong, Chunle; Collins, Matthew J.; Choi, Duk-Yong; Joon Chae, Chang; Liscidini, Marco; Steel, M. J.; Eggleton, Benjamin J.; Clark, Alex S.

2015-01-01

The growing requirement for photon pairs with specific spectral correlations in quantum optics experiments has created a demand for fast, high resolution and accurate source characterisation. A promising tool for such characterisation uses classical stimulated processes, in which an additional seed laser stimulates photon generation yielding much higher count rates, as recently demonstrated for a χ(2) integrated source in A. Eckstein et al. Laser Photon. Rev. 8, L76 (2014). In this work we extend these results to χ(3) integrated sources, directly measuring for the first time the relation between spectral correlation measurements via stimulated and spontaneous four wave mixing in an integrated optical waveguide, a silicon nanowire. We directly confirm the speed-up due to higher count rates and demonstrate that this allows additional resolution to be gained when compared to traditional coincidence measurements without any increase in measurement time. As the pump pulse duration can influence the degree of spectral correlation, all of our measurements are taken for two different pump pulse widths. This allows us to confirm that the classical stimulated process correctly captures the degree of spectral correlation regardless of pump pulse duration, and cements its place as an essential characterisation method for the development of future quantum integrated devices. PMID:26218609

[Research on the measurement of flue-dust concentration in Vis, IR spectral region].

PubMed

Sun, Xiao-gang; Tang, Hong; Yuan, Gui-bin

2008-10-01

In the measurement of flue-dust concentration based on the transmission method, the dependent model algorithm was used to invert the flue-dust concentration in the visible, infrared and visible-infrared spectral regions respectively. By the analysis and comparison of the accuracy, linearity and sensitivity of the inversion flue-dust concentration, the optimal spectral region was determined. Meanwhile, the influence of the water droplet with different size distribution and volume concentration was simulated, and a method was proposed which has advantages of simplicity, rapidity, and suitability for on line measurement. Simulation experiments illustrate that the flue-dust concentration can be inverted very well in the visible-infrared spectral region, and it is feasible to use the ratio of the constrained light extinction method to overcome the influence of water droplet. The inverse results all remain satisfactory when 2% stochastic noise is added to the value of the light extinction.

Measurements of thermal infrared spectral reflectance of frost, snow, and ice

NASA Technical Reports Server (NTRS)

Salisbury, John W.; D'Aria, Dana M.; Wald, Andrew

1994-01-01

Because much of Earth's surface is covered by frost, snow, and ice, the spectral emissivities of these materials are a significant input to radiation balance calculations in global atmospheric circulation and climate change models. Until now, however, spectral emissivities of frost and snow have been calculated from the optical constants of ice. We have measured directional hemispherical reflectance spectra of frost, snow, and ice from which emissivities can be predicted using Kirchhoff's law (e = 1-R). These measured spectra show that contrary to conclusions about the emissivity of snow drawn from previously calculated spectra, snow emissivity departs significantly from blackbody behavior in the 8-14 micrometer region of the spectrum; snow emissivity decreases with both increasing particle size and increasing density due to packing or grain welding; while snow emissivity increases due to the presence of meltwater.

Velocity and Temperature Measurement in Supersonic Free Jets Using Spectrally Resolved Rayleigh Scattering

NASA Technical Reports Server (NTRS)

Panda, J.; Seasholtz, R. G.

2004-01-01

The flow fields of unheated, supersonic free jets from convergent and convergent-divergent nozzles operating at M = 0.99, 1.4, and 1.6 were measured using spectrally resolved Rayleigh scattering technique. The axial component of velocity and temperature data as well as density data obtained from a previous experiment are presented in a systematic way with the goal of producing a database useful for validating computational fluid dynamics codes. The Rayleigh scattering process from air molecules provides a fundamental means of measuring flow properties in a non-intrusive, particle free manner. In the spectrally resolved application, laser light scattered by the air molecules is collected and analyzed using a Fabry-Perot interferometer (FPI). The difference between the incident laser frequency and the peak of the Rayleigh spectrum provides a measure of gas velocity. The temperature is measured from the spectral broadening caused by the random thermal motion and density is measured from the total light intensity. The present point measurement technique uses a CW laser, a scanning FPI and photon counting electronics. The 1 mm long probe volume is moved from point to point to survey the flow fields. Additional arrangements were made to remove particles from the main as well as the entrained flow and to isolate FPI from the high sound and vibration levels produced by the supersonic jets. In general, velocity is measured within +/- 10 m/s accuracy and temperature within +/- 10 K accuracy.

Space debris measurement program at Phillips Laboratory

NASA Technical Reports Server (NTRS)

Dao, Phan D.; Mcnutt, Ross T.

1992-01-01

Ground-based optical sensing was identified as a technique for measuring space debris complementary to radar in the critical debris size range of 1 to 10 cm. The Phillips Laboratory is building a staring optical sensor for space debris measurement and considering search and track optical measurement at additional sites. The staring sensor is implemented in collaboration with Wright Laboratory using the 2.5 m telescope at Wright Patterson AFB, Dayton, Ohio. The search and track sensor is designed to detect and track orbital debris in tasked orbits. A progress report and a discussion of sensor performance and search and track strategies will be given.

Thermal Infrared Spectral Band Detection Limits for Unidentified Surface Materials

NASA Technical Reports Server (NTRS)

Kirkland, Laurel E.; Herr, Kenneth C.; Salisbury, John W.

2001-01-01

Infrared emission spectra recorded by airborne or satellite spectrometers can be searched for spectral features to determine the composition of rocks on planetary surfaces. Surface materials are identified by detections of characteristic spectral bands. We show how to define whether to accept an observed spectral feature as a detection when the target material is unknown. We also use remotely sensed spectra measured by the Thermal Emission Spectrometer (TES) and the Spatially Enhanced Broadband Array Spectrograph System to illustrate the importance of instrument parameters and surface properties on band detection limits and how the variation in signal-to-noise ratio with wavelength affects the bands that are most detectable for a given instrument. The spectrometer's sampling interval, spectral resolution, signal-to-noise ratio as a function of wavelength, and the sample's surface properties influence whether the instrument can detect a spectral feature exhibited by a material. As an example, in the 6-13 micrometer wavelength region, massive carbonates exhibit two bands: a very strong, broad feature at approximately 6.5 micrometers and a less intense, sharper band at approximately 11.25 micrometers. Although the 6.5-micrometer band is stronger and broader in laboratory-measured spectra, the 11.25-micrometer band will cause a more detectable feature in TES spectra.

Dielectric property measurements in the Electromagnetic Properties Measurement Laboratory

NASA Technical Reports Server (NTRS)

Cravey, Robin L.; Tiemsin, Pacita I.; Bussell, Kerri; Dudley, Kenneth L.

1995-01-01

The capability to measure the dielectric properties of various materials has been developed in the Electromagnetic Properties Measurement Laboratory (EPML) of the Electromagnetics Research Branch (ERB). Two measurement techniques which have been implemented in the EPML to characterize materials are the dielectric probe and waveguide techniques. Several materials, including some for which the dielectric properties are well known, have been measured in an attempt to establish the capabilities of the EPML in determining dielectric properties. Brief descriptions of the two techniques are presented in this report, along with representative results obtained during these measurements.

Reliability of laboratory measurement of human food intake.

PubMed

Laessle, R; Geiermann, L

2012-02-01

The universal eating monitor (UEM) of Kissileff for laboratory measurement of food intake was modified and used with a newly developed special software to compute cumulative intake data. To explore the measurement precision of the UEM an investigation of test-retest-reliability of food intake parameters was conducted. The intake characteristics of 125 males and females were measured repeatedly in the laboratory with a measurement interval of 1 week. Pudding of preferred flavour served as test meal. Test-retest-reliability of intake characteristics ranged from .49 (change of eating rate) to .89 (initial eating rate). All test-retest correlations were highly significant. Sex, BMI and eating habits according to TFEQ-factors had no significant effects on reliability of intake characteristics. The test-retest-reliability of the laboratory intake measures is as good as those of personality questionnaires, where it should be better than .80. Reliability coefficients are valid independent of sex, BMI or trait characteristics of eating behaviour. Copyright © 2011 Elsevier Ltd. All rights reserved.

Diode laser spectroscopy: precise spectral line shape measurements

NASA Astrophysics Data System (ADS)

Nadezhdinskii, A. I.

1996-07-01

When one speaks about modern trends in tunable diode laser spectroscopy (TDLS) one should mention that precise line shape measurements have become one of the most promising applications of diode lasers in high resolution molecular spectroscopy. Accuracy limitations of TDL spectrometers are considered in this paper, proving the ability to measure spectral line profile with precision better than 1%. A four parameter Voigt profile is used to fit the experimental spectrum, and the possibility of line shift measurements with an accuracy of 2 × 10 -5 cm -1 is shown. Test experiments demonstrate the error line intensity ratios to be less than 0.3% for the proposed approach. Differences between "soft" and "hard" models of line shape have been observed experimentally for the first time. Some observed resonance effects are considered with respect to collision adiabacity.

Dosimetry in MARS spectral CT: TOPAS Monte Carlo simulations and ion chamber measurements.

PubMed

Lu, Gray; Marsh, Steven; Damet, Jerome; Carbonez, Pierre; Laban, John; Bateman, Christopher; Butler, Anthony; Butler, Phil

2017-06-01

Spectral computed tomography (CT) is an up and coming imaging modality which shows great promise in revealing unique diagnostic information. Because this imaging modality is based on X-ray CT, it is of utmost importance to study the radiation dose aspects of its use. This study reports on the implementation and evaluation of a Monte Carlo simulation tool using TOPAS for estimating dose in a pre-clinical spectral CT scanner known as the MARS scanner. Simulated estimates were compared with measurements from an ionization chamber. For a typical MARS scan, TOPAS estimated for a 30 mm diameter cylindrical phantom a CT dose index (CTDI) of 29.7 mGy; CTDI was measured by ion chamber to within 3% of TOPAS estimates. Although further development is required, our investigation of TOPAS for estimating MARS scan dosimetry has shown its potential for further study of spectral scanning protocols and dose to scanned objects.

Errors in short circuit measurements due to spectral mismatch between sunlight and solar simulators

NASA Technical Reports Server (NTRS)

Curtis, H. B.

1976-01-01

Errors in short circuit current measurement were calculated for a variety of spectral mismatch conditions. The differences in spectral irradiance between terrestrial sunlight and three types of solar simulator were studied, as well as the differences in spectral response between three types of reference solar cells and various test cells. The simulators considered were a short arc xenon lamp AMO sunlight simulator, an ordinary quartz halogen lamp, and an ELH-type quartz halogen lamp. Three types of solar cells studied were a silicon cell, a cadmium sulfide cell and a gallium arsenide cell.

A precise laboratory goniometer system to collect spectral BRDF data of materials

NASA Astrophysics Data System (ADS)

Jiao, Guangping; Jiao, Ziti; Wang, Jie; Zhang, Hu; Dong, Yadong

2014-11-01

This paper presents a precise laboratory goniometer system to quickly collect bidirectional reflectance distribution factor(BRDF)of typical materials such soil, canopy and artificial materials in the laboratory. The system consists of the goniometer, SVC HR1024 spectroradiometer, and xenon long-arc lamp as light source. the innovation of cantilever slab can reduce the shadow of the goniometer in the principle plane. The geometric precision of the footprint centre is better than +/-4cm in most azimuth directions, and the angle-controlling accuracy is better than 0.5°. The light source keeps good stability, with 0.8% irradiance decrease in 3 hours. But the large areal heterogeneity of the light source increase the data processing difficulty to capture the accurate BRDF. First measurements are taken from soil in a resolution of 15° and 30° in zenith and azimuth direction respectively, with the +/-50° biggest view angle. More observations are taken in the hot-spot direction. The system takes about 40 minutes to complete all measurements. A spectralon panel is measured at the beginning and end of the whole period. A simple interactive interface on the computer can automatically control all operations of the goniometer and data-processing. The laboratory experiment of soil layer and grass lawn shows that the goniometer can capture the the multi-angle variation of BRDF.

Harmonization in laboratory medicine: Requests, samples, measurements and reports.

PubMed

Plebani, Mario

2016-01-01

In laboratory medicine, the terms "standardization" and "harmonization" are frequently used interchangeably as the final goal is the same: the equivalence of measurement results among different routine measurement procedures over time and space according to defined analytical and clinical quality specifications. However, the terms define two distinct, albeit closely linked, concepts based on traceability principles. The word "standardization" is used when results for a measurement are equivalent and traceable to the International System of Units (SI) through a high-order primary reference material and/or a reference measurement procedure (RMP). "Harmonization" is generally used when results are equivalent, but neither a high-order primary reference material nor a reference measurement procedure is available. Harmonization is a fundamental aspect of quality in laboratory medicine as its ultimate goal is to improve patient outcomes through the provision of accurate and actionable laboratory information. Patients, clinicians and other healthcare professionals assume that clinical laboratory tests performed by different laboratories at different times on the same sample and specimen can be compared, and that results can be reliably and consistently interpreted. Unfortunately, this is not necessarily the case, because many laboratory test results are still highly variable and poorly standardized and harmonized. Although the initial focus was mainly on harmonizing and standardizing analytical processes and methods, the scope of harmonization now also includes all other aspects of the total testing process (TTP), such as terminology and units, report formats, reference intervals and decision limits as well as tests and test profiles, requests and criteria for interpretation. Several projects and initiatives aiming to improve standardization and harmonization in the testing process are now underway. Laboratory professionals should therefore step up their efforts to provide

High Spectral Resolution Lidar Measurements of Multiple Scattering

NASA Technical Reports Server (NTRS)

Eloranta, E. W.; Piironen, P.

1996-01-01

The University of Wisconsin High Spectral Resolution Lidar (HSRL) provides unambiguous measurements of backscatter cross section, backscatter phase function, depolarization, and optical depth. This is accomplished by dividing the lidar return into separate particulate and molecular contributions. The molecular return is then used as a calibration target. We have modified the HSRL to use an I2 molecular absorption filter to separate aerosol and molecular signals. This allows measurement in dense clouds. Useful profiles extend above the cloud base until the two way optical depth reaches values between 5 and 6; beyond this, photon counting errors become large. In order to observe multiple scattering, the HSRL includes a channel which records the combined aerosol and molecular lidar return simultaneously with the spectrometer channel measurements of optical properties. This paper describes HSRL multiple scattering measurements from both water and ice clouds. These include signal strengths and depolarizations as a function of receiver field of view. All observations include profiles of extinction and backscatter cross sections. Measurements are also compared to predictions of a multiple scattering model based on small angle approximations.

Solid laboratory calibration of a nonimaging spectroradiometer.

PubMed

Schaepman, M E; Dangel, S

2000-07-20

Field-based nonimaging spectroradiometers are often used in vicarious calibration experiments for airborne or spaceborne imaging spectrometers. The calibration uncertainties associated with these ground measurements contribute substantially to the overall modeling error in radiance- or reflectance-based vicarious calibration experiments. Because of limitations in the radiometric stability of compact field spectroradiometers, vicarious calibration experiments are based primarily on reflectance measurements rather than on radiance measurements. To characterize the overall uncertainty of radiance-based approaches and assess the sources of uncertainty, we carried out a full laboratory calibration. This laboratory calibration of a nonimaging spectroradiometer is based on a measurement plan targeted at achieving a spectral sampling interval, the nonlinearity, directional and positional effects, the spectral scattering, the field of view, the polarization, the size-of-source effects, and the temperature dependence of a particular instrument. The traceability of the radiance calibration is established to a secondary National Institute of Standards and Technology calibration standard by use of a 95% confidence interval and results in an uncertainty of less than ?7.1% for all spectroradiometer bands.

Spectral emissivity of cirrus clouds

NASA Technical Reports Server (NTRS)

Beck, Gordon H.; Davis, John M.; Cox, Stephen K.

1993-01-01

The inference of cirrus cloud properties has many important applications including global climate studies, radiation budget determination, remote sensing techniques and oceanic studies from satellites. Data taken at the Parsons Kansas site during the FIRE II project are used for this study. On November 26 there were initially clear sky conditions gradually giving way to a progressively thickening cirrus shield over a period of a few hours. Interferometer radiosonde and lidar data were taken throughout this event. Two techniques are used to infer the downward spectral emittance of the observed cirrus layer. One uses only measurements and the other involves measurements and FASCODE III calculations. FASCODE III is a line-by line radiance/transmittance model developed at the Air Force Geophysics Laboratory.

Spectral emissivity and transmissivity measurement for zinc sulphide infrared window based on integrating-sphere reflectometry

NASA Astrophysics Data System (ADS)

Zhang, Yu-Feng; Dai, Jing-Min; Zhang, Lei; Pan, Wei-Dong

2013-08-01

The spectral emissivity and transmissivity of zinc sulphide (ZnS) infrared windows in the spectral region from 2 to 12 μm and temperature range from 20 to 700°C is measured by a facility built at the Harbin Institute of Technology (HIT). The facility is based on the integrating-sphere reflectometry. Measurements have been performed on two samples made of ZnS. The results measured at 20°C are in good agreement with those obtained by the method of radiant energy comparison using a Fourier transform infrared spectrometer. Emissivity measurements performed with this facility present an uncertainty of 5.5% (cover factor=2).

Laboratory Measurements of Celestial Solids

NASA Technical Reports Server (NTRS)

Sievers, A. J.; Beckwith, S. V. W.

1997-01-01

Our experimental study has focused on laboratory measurements of the low temperature optical properties of a variety of astronomically significant materials in the infrared and mm-wave region of the spectrum. Our far infrared measurements of silicate grains with an open structure have produced a variety of unusual results: (1) the low temperature mass opacity coefficient of small amorphous 2MgO(central dot)SiO2 and MgO(central dot)2SiO2 grains are many times larger than the values previously used for interstellar grain material; (2) all of the amorphous silicate grains studied possess the characteristic temperature dependent signature associated with two level systems in bulk glass; and (3) a smaller but nonzero two level temperature dependence signature is also observed for crystalline particles, its physical origin is unclear. These laboratory measurements yield surprisingly large and variable values for the mm-wave absorption coefficients of small silicate particles similar to interstellar grains, and suggest that the bulk absorptivity of interstellar dust at these long wavelengths will not be well known without such studies. Furthermore, our studies have been useful to better understand the physics of the two level absorption process in amorphous and crystalline grains to gain confidence in the wide applicability of these results.

Laboratory investigations

NASA Technical Reports Server (NTRS)

Russell, Ray W.

1988-01-01

Laboratory studies related to cometary grains and the nuclei of comets can be broken down into three areas which relate to understanding the spectral properties, the formation mechanisms, and the evolution of grains and nuclei: (1) Spectral studies to be used in the interpretation of cometary spectra; (2) Sample preparation experiments which may shed light on the physical nature and history of cometary grains and nuclei by exploring the effects on grain emissivities resulting from the ways in which the samples are created; and (3) Grain processing experiments which should provide insight on the interaction of cometary grains with the environment in the immediate vicinity of the cometary nucleus as the comet travels from the Oort cloud through perihelion, and perhaps even suggestions regarding the relationship between interstellar grains and cometary matter. A summary is presented with a different view of lab experiments than is found in the literature, concentrating on measurement techniques and sample preparations especially relevant to cometary dust.

Airborne Spectral Measurements of Surface-Atmosphere Anisotropy for Skukuza and Mongu Sites

NASA Technical Reports Server (NTRS)

Gatebe, C. K.; King, Michael D.; Arnold, G. T.; Li, J. Y.

2001-01-01

The Cloud Absorption Radiometer (CAR) was flown aboard the University of Washington Convair CV-580 research aircraft and took measurements on 23 flights between August 15 and September 16. On 12 of those flights, BRF (bidirectional reflection function) measurements were obtained over different natural surfaces and ecosystems in southern Africa. The BRF measurements were done to characterize surface anisotropy in support of SAFARI 2000 science objectives principally to validate products from NASA's EOS (Earth Observing System) satellites, and to parameterize and validate BRF models. In this paper we present results of BRFs taken over two EOS validation sites: Skukuza tower, South Africa (25.0 S, 31.5 E) and Mongu tower, Zambia (15.4 S, 23.3 E). The CAR is capable of measuring scattered light in fourteen spectral bands. The scan mirror, rotating at 100 rpm, directs the light into a Dall-Kirkham telescope where the beam is split into nine paths. Eight light beams pass through beam splitters, dichroics, and lenses to individual detectors (0.34-1.27 microns), and finally are registered by eight data channels. They are sampled simultaneously and continuously. The ninth beam passes through a spinning filter wheel to an InSb detector cooled by a Stirling cycle cooler. Signals registered by the ninth data channel are selected from among six spectral channels (1.55-2.30 microns). The filter wheel can either cycle through all six spectral bands at a prescribed interval (usually changing filter every fifth scan line), or lock onto any one of the six spectral bands and sample it continuously. To measure the BRF of the surface-atmosphere system, the University of Washington CV-580 had to bank at a comfortable roll angle of approximately 20 degrees and fly in a circle about 3 km in diameter above the surface for roughly two minutes. Replicated observations (multiple circular orbits) were acquired over selected surfaces so that average BRF smooth out small-scale surface and

Measuring and Modeling the Effect of Surface Moisture on the Spectral Reflectance of Coastal Beach Sand

PubMed Central

Nolet, Corjan; Poortinga, Ate; Roosjen, Peter; Bartholomeus, Harm; Ruessink, Gerben

2014-01-01

Surface moisture is an important supply limiting factor for aeolian sand transport, which is the primary driver of coastal dune development. As such, it is critical to account for the control of surface moisture on available sand for dune building. Optical remote sensing has the potential to measure surface moisture at a high spatio-temporal resolution. It is based on the principle that wet sand appears darker than dry sand: it is less reflective. The goals of this study are (1) to measure and model reflectance under controlled laboratory conditions as function of wavelength () and surface moisture () over the optical domain of 350–2500 nm, and (2) to explore the implications of our laboratory findings for accurately mapping the distribution of surface moisture under natural conditions. A laboratory spectroscopy experiment was conducted to measure spectral reflectance (1 nm interval) under different surface moisture conditions using beach sand. A non-linear increase of reflectance upon drying was observed over the full range of wavelengths. Two models were developed and tested. The first model is grounded in optics and describes the proportional contribution of scattering and absorption of light by pore water in an unsaturated sand matrix. The second model is grounded in soil physics and links the hydraulic behaviour of pore water in an unsaturated sand matrix to its optical properties. The optical model performed well for volumetric moisture content 24% ( 0.97), but underestimated reflectance for between 24–30% ( 0.92), most notable around the 1940 nm water absorption peak. The soil-physical model performed very well ( 0.99) but is limited to 4% 24%. Results from a field experiment show that a short-wave infrared terrestrial laser scanner ( = 1550 nm) can accurately relate surface moisture to reflectance (standard error 2.6%), demonstrating its potential to derive spatially extensive surface moisture maps of a natural coastal beach. PMID:25383709

Design principles and field performance of a solar spectral irradiance meter

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

Tatsiankou, V.; Hinzer, K.; Haysom, J.

2016-08-01

A solar spectral irradiance meter (SSIM), designed for measuring the direct normal irradiance (DNI) in six wavelength bands, has been combined with models to determine key atmospheric transmittances and the resulting spectral irradiance distribution of DNI under all sky conditions. The design principles of the SSIM, implementation of a parameterized transmittance model, and field performance comparisons of modeled solar spectra with reference radiometer measurements are presented. Two SSIMs were tested and calibrated at the National Renewable Energy Laboratory (NREL) against four spectroradiometers and an absolute cavity radiometer. The SSIMs' DNI was on average within 1% of the DNI values reportedmore » by one of NREL's primary absolute cavity radiometers. An additional SSIM was installed at the SUNLAB Outdoor Test Facility in September 2014, with ongoing collection of environmental and spectral data. The SSIM's performance in Ottawa was compared against a commercial pyrheliometer and a spectroradiometer over an eight month study. The difference in integrated daily spectral irradiance between the SSIM and the ASD spectroradiometer was found to be less than 1%. The cumulative energy density collected by the SSIM over this duration agreed with that measured by an Eppley model NIP pyrheliometer to within 0.5%. No degradation was observed.« less

Laboratory ginning and blending impacts on cotton fiber micronaire measurements

USDA-ARS?s Scientific Manuscript database

Micronaire, a critical cotton quality parameter, is normally measured in a conditioned laboratory, but increasing interest has been shown in new technologies that can measure micronaire both in and outside of the laboratory. Near Infrared (NIR) technology has demonstrated its ability to measure cot...

Divertor electron temperature and impurity diffusion measurements with a spectrally resolved imaging radiometer.

PubMed

Clayton, D J; Jaworski, M A; Kumar, D; Stutman, D; Finkenthal, M; Tritz, K

2012-10-01

A divertor imaging radiometer (DIR) diagnostic is being studied to measure spatially and spectrally resolved radiated power P(rad)(λ) in the tokamak divertor. A dual transmission grating design, with extreme ultraviolet (~20-200 Å) and vacuum ultraviolet (~200-2000 Å) gratings placed side-by-side, can produce coarse spectral resolution over a broad wavelength range covering emission from impurities over a wide temperature range. The DIR can thus be used to evaluate the separate P(rad) contributions from different ion species and charge states. Additionally, synthetic spectra from divertor simulations can be fit to P(rad)(λ) measurements, providing a powerful code validation tool that can also be used to estimate electron divertor temperature and impurity transport.

Spectro-Polarimetry of Fine-Grained Ice and Dust Surfaces Measured in the Laboratory to Study Solar System Objects and Beyond

NASA Astrophysics Data System (ADS)

Poch, O.; Cerubini, R.; Pommerol, A.; Thomas, N.; Schmid, H. M.; Potin, S.; Beck, P.; Schmitt, B.; Brissaud, O.; Carrasco, N.; Szopa, C.; Buch, A.

2017-12-01

The polarization of the light is very sensitive to the size, morphology, porosity and composition of the scattering particles. As a consequence, polarimetric observations could significantly complement observations performed in total light intensity, providing additional constraints to interpret remote sensing observations of Solar System and extra-solar objects. This presentation will focus on measurements performed in the laboratory on carefully characterized surface samples, providing reference data that can be used to test theoretical models and predict or interpret spectro-polarimetric observations. Using methods developed in the Laboratory for Outflow Studies of Sublimating Materials (LOSSy) at the University of Bern, we produce well-characterized and reproducible surfaces made of water ice particles having different grain sizes and porosities, as well as mineral/organic dusts, pure or mixed together, as analogues of planetary or small bodies surfaces. These surface samples are illuminated with a randomly polarized light source simulating the Sun. The polarization of their scattered light is measured at multiple phase angles and wavelengths, allowing to study the shape of the polarimetric phase curves and their spectral dependence, with two recently developed setups: The POLarimeter for Icy Samples (POLICES), at the University of Bern, allows the measurement of the weak polarization of ice surfaces from 400 to 800 nm, with direct application to icy satellites. Using a precision Stokes polarimeter, this setup is also used to study the spectral variations of circular polarization in the light scattered by biotic versus abiotic surfaces. The Spectrogonio radiometer with cHanging Angles for Detection Of Weak Signals (SHADOWS), at IPAG (University of Grenoble Alpes), measures linear polarization spectra from 0.35 to 5 μm in the light scattered by dark meteorite powders or icy samples, with application to primitive objects of the Solar System (asteroids, comets).

Aerosol Retrieval from Multiangle Multispectral Photopolarimetric Measurements: Importance of Spectral Range and Angular Resolution

NASA Technical Reports Server (NTRS)

Wu, L.; Hasekamp, O.; Van Diedenhoven, B.; Cairns, B.

2015-01-01

We investigated the importance of spectral range and angular resolution for aerosol retrieval from multiangle photopolarimetric measurements over land. For this purpose, we use an extensive set of simulated measurements for different spectral ranges and angular resolutions and subsets of real measurements of the airborne Research Scanning Polarimeter (RSP) carried out during the PODEX and SEAC4RS campaigns over the continental USA. Aerosol retrievals performed from RSP measurements show good agreement with ground-based AERONET measurements for aerosol optical depth (AOD), single scattering albedo (SSA) and refractive index. Furthermore, we found that inclusion of shortwave infrared bands (1590 and/or 2250 nm) significantly improves the retrieval of AOD, SSA and coarse mode microphysical properties. However, accuracies of the retrieved aerosol properties do not improve significantly when more than five viewing angles are used in the retrieval.

Simulating airless and/or hot planetary surfaces in the Planetary Emissivity Laboratory (PEL)

NASA Astrophysics Data System (ADS)

Maturilli, A.; Helbert, J.; D'Amore, M.

2010-12-01

A complete and extensive mineralogical survey of extraterrestrial bodies is actually possible only by means of remote sensing spectrometers, measuring the planetary surfaces in a spectral range that goes from the visible to the far infrared. The list of instruments still active today, observing the most interesting planets and bodies in our solar system is far too long to list them in this abstract. The important message is that all of them are sending to Earth a huge amount of data that needs to be correctly analysed, to infer the mineralogical composition of the observed regions on different targets. This requires laboratory data of relevant analogue materials under relevant conditions measured on a wide spectral range. At the Planetary Emissivity Laboratory (PEL) of DLR in Berlin two separate instruments, a Bruker IFS 88 and a Bruker Vertex 80V are operated in parallel and independently to measure reflectance and emissivity of planetary analogue materials to cover the 0.4 to 100 µm spectral range. The older IFS 88 is used to measure under room pressure and for emissivity measurements from low to moderate temperatures (up to 180° C), while the new Vertex 80V can be evacuated (below 1 mbar) and used to measure emissivity of moderate to very hot surfaces, reaching temperatures typical of the daily Mercury (beyond 500° C). The laboratory set-up and the already obtained results will be described, together with details about the online-archival and the standardized structure of the existing dataset.

The spectral response of Buxus sempervirens to different types of environmental stress - A laboratory experiment

NASA Astrophysics Data System (ADS)

de Jong, Steven M.; Addink, Elisabeth A.; Hoogenboom, Priscilla; Nijland, Wiebe

2012-11-01

The European Mediterranean regions are expected to encounter drier summer conditions and warmer temperatures for the winter of +2 °C and of +5 °C for the summer in the next six decennia. As a result the natural vegetation will face harsher conditions due to lower water availability, longer summer droughts and higher temperatures resulting in plant stress conditions. To monitor vegetation conditions like stress and leaf area index dynamics in our study area in Mediterranean France we use earth observation techniques like imaging spectroscopy. To assist image analysis interpretation we carried out a laboratory experiment to investigate the spectral and visible response of Buxus sempervirens, a common Mediterranean species, to five different types of stress: drought, drought-and-heat, light deprivation, total saturation and chlorine poisoning. For 52 days plants were subjected to stress. We collected data on the visible and spectral signs, and calculated thirteen vegetation indices. The plant's response time to different stress types varied from 10 to 32 days. Spectroscopic techniques revealed plant stress up to 15 days earlier than visual inspection. Visible signs of stress of the plants included curling and shrinking of the leaves, de-colouring of the leaves, leaves becoming breakable, opening up of the plant's canopy and sagging of the branches. Spectral signs of stress occurred first in the water absorption bands at 1450 and 1940 nm, followed by reduced absorption in the visible wavelengths, and next by reduced reflectance in near infrared. Light deprivation did not result in any stress signs, while drought, drought and heat and chlorine poisoning resulted in significant stress. The spectral response did not show differences for different stress types. Analysis of the vegetation indices identified the Carter-2 (R695/R760), the Red-Green Index (R690/R550) and the Vogelman-2 (R734 - R747)/(R715 + R726) as the best performing ones to identify stress. The lab

Effect of musical training on static and dynamic measures of spectral-pattern discrimination.

PubMed

Sheft, Stanley; Smayda, Kirsten; Shafiro, Valeriy; Maddox, W Todd; Chandrasekaran, Bharath

2013-06-01

Both behavioral and physiological studies have demonstrated enhanced processing of speech in challenging listening environments attributable to musical training. The relationship, however, of this benefit to auditory abilities as assessed by psychoacoustic measures remains unclear. Using tasks previously shown to relate to speech-in-noise perception, the present study evaluated discrimination ability for static and dynamic spectral patterns by 49 listeners grouped as either musicians or nonmusicians. The two static conditions measured the ability to detect a change in the phase of a logarithmic sinusoidal spectral ripple of wideband noise with ripple densities of 1.5 and 3.0 cycles per octave chosen to emphasize either timbre or pitch distinctions, respectively. The dynamic conditions assessed temporal-pattern discrimination of 1-kHz pure tones frequency modulated by different lowpass noise samples with thresholds estimated in terms of either stimulus duration or signal-to-noise ratio. Musicians performed significantly better than nonmusicians on all four tasks. Discriminant analysis showed that group membership was correctly predicted for 88% of the listeners with the structure coefficient of each measure greater than 0.51. Results suggest that enhanced processing of static and dynamic spectral patterns defined by low-rate modulation may contribute to the relationship between musical training and speech-in-noise perception. [Supported by NIH.].

Spectral relative standard deviation: a practical benchmark in metabolomics.

PubMed

Parsons, Helen M; Ekman, Drew R; Collette, Timothy W; Viant, Mark R

2009-03-01

Metabolomics datasets, by definition, comprise of measurements of large numbers of metabolites. Both technical (analytical) and biological factors will induce variation within these measurements that is not consistent across all metabolites. Consequently, criteria are required to assess the reproducibility of metabolomics datasets that are derived from all the detected metabolites. Here we calculate spectrum-wide relative standard deviations (RSDs; also termed coefficient of variation, CV) for ten metabolomics datasets, spanning a variety of sample types from mammals, fish, invertebrates and a cell line, and display them succinctly as boxplots. We demonstrate multiple applications of spectral RSDs for characterising technical as well as inter-individual biological variation: for optimising metabolite extractions, comparing analytical techniques, investigating matrix effects, and comparing biofluids and tissue extracts from single and multiple species for optimising experimental design. Technical variation within metabolomics datasets, recorded using one- and two-dimensional NMR and mass spectrometry, ranges from 1.6 to 20.6% (reported as the median spectral RSD). Inter-individual biological variation is typically larger, ranging from as low as 7.2% for tissue extracts from laboratory-housed rats to 58.4% for fish plasma. In addition, for some of the datasets we confirm that the spectral RSD values are largely invariant across different spectral processing methods, such as baseline correction, normalisation and binning resolution. In conclusion, we propose spectral RSDs and their median values contained herein as practical benchmarks for metabolomics studies.

Measurement of breast-tissue x-ray attenuation by spectral mammography: solid lesions

NASA Astrophysics Data System (ADS)

Fredenberg, Erik; Kilburn-Toppin, Fleur; Willsher, Paula; Moa, Elin; Danielsson, Mats; Dance, David R.; Young, Kenneth C.; Wallis, Matthew G.

2016-04-01

Knowledge of x-ray attenuation is essential for developing and evaluating x-ray imaging technologies. For instance, techniques to distinguish between cysts and solid tumours at mammography screening would be highly desirable to reduce recalls, but the development requires knowledge of the x-ray attenuation for cysts and tumours. We have previously measured the attenuation of cyst fluid using photon-counting spectral mammography. Data on x-ray attenuation for solid breast lesions are available in the literature, but cover a relatively wide range, likely caused by natural spread between samples, random measurement errors, and different experimental conditions. In this study, we have adapted a previously developed spectral method to measure the linear attenuation of solid breast lesions. A total of 56 malignant and 5 benign lesions were included in the study. The samples were placed in a holder that allowed for thickness measurement. Spectral (energy-resolved) images of the samples were acquired and the image signal was mapped to equivalent thicknesses of two known reference materials, which can be used to derive the x-ray attenuation as a function of energy. The spread in equivalent material thicknesses was relatively large between samples, which is likely to be caused mainly by natural variation and only to a minor extent by random measurement errors and sample inhomogeneity. No significant difference in attenuation was found between benign and malignant solid lesions. The separation between cyst-fluid and tumour attenuation was, however, significant, which suggests it may be possible to distinguish cystic from solid breast lesions, and the results lay the groundwork for a clinical trial. In addition, the study adds a relatively large sample set to the published data and may contribute to a reduction in the overall uncertainty in the literature.

Information Measures for Multisensor Systems

DTIC Science & Technology

2013-12-11

permuted to generate spectra that were non- physical but preserved the entropy of the source spectra. Another 1000 spectra were constructed to mimic co...Research Laboratory (NRL) has yielded probabilistic models for spectral data that enable the computation of information measures such as entropy and...22308 Chemical sensing Information theory Spectral data Information entropy Information divergence Mass spectrometry Infrared spectroscopy Multisensor

Advances in atmospheric temperature profile measurements using high spectral resolution lidar

NASA Astrophysics Data System (ADS)

Razenkov, Ilya I.; Eloranta, Edwin W.

2018-04-01

This paper reports the atmospheric temperature profile measurements using a University of Wisconsin-Madison High Spectral Resolution Lidar (HSRL) and describes improvements in the instrument performance. HSRL discriminates between Mie and Rayleigh backscattering [1]. Thermal motion of molecules broadens the spectrum of the transmitted laser light due to Doppler effect. The HSRL exploits this property to allow the absolute calibration of the lidar and measurements of the aerosol volume backscatter coefficient. Two iodine absorption filters with different line widths are used to resolve temperature sensitive changes in Rayleigh backscattering for atmospheric temperature profile measurements.

Single shot, double differential spectral measurements of inverse Compton scattering in the nonlinear regime

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

Sakai, Y.; Gadjev, I.; Hoang, P.

Inverse Compton scattering (ICS) is a unique mechanism for producing fast pulses$-$picosecond and below$-$of bright photons, ranging from x to γ rays. These nominally narrow spectral bandwidth electromagnetic radiation pulses are efficiently produced in the interaction between intense, well-focused electron and laser beams. The spectral characteristics of such sources are affected by many experimental parameters, with intense laser effects often dominant. A laser field capable of inducing relativistic oscillatory motion may give rise to harmonic generation and, importantly for the present work, nonlinear redshifting, both of which dilute the spectral brightness of the radiation. As the applications enabled by thismore » source often depend sensitively on its spectra, it is critical to resolve the details of the wavelength and angular distribution obtained from ICS collisions. With this motivation, we present an experimental study that greatly improves on previous spectral measurement methods based on x-ray K -edge filters, by implementing a multilayer bent-crystal x-ray spectrometer. In tandem with a collimating slit, this method reveals a projection of the double differential angular-wavelength spectrum of the ICS radiation in a single shot. The measurements enabled by this diagnostic illustrate the combined off-axis and nonlinear-field-induced redshifting in the ICS emission process. The spectra obtained illustrate in detail the strength of the normalized laser vector potential, and provide a nondestructive measure of the temporal and spatial electron-laser beam overlap.« less

Single shot, double differential spectral measurements of inverse Compton scattering in the nonlinear regime

DOE PAGES

Sakai, Y.; Gadjev, I.; Hoang, P.; ...

2017-06-05

Inverse Compton scattering (ICS) is a unique mechanism for producing fast pulses$-$picosecond and below$-$of bright photons, ranging from x to γ rays. These nominally narrow spectral bandwidth electromagnetic radiation pulses are efficiently produced in the interaction between intense, well-focused electron and laser beams. The spectral characteristics of such sources are affected by many experimental parameters, with intense laser effects often dominant. A laser field capable of inducing relativistic oscillatory motion may give rise to harmonic generation and, importantly for the present work, nonlinear redshifting, both of which dilute the spectral brightness of the radiation. As the applications enabled by thismore » source often depend sensitively on its spectra, it is critical to resolve the details of the wavelength and angular distribution obtained from ICS collisions. With this motivation, we present an experimental study that greatly improves on previous spectral measurement methods based on x-ray K -edge filters, by implementing a multilayer bent-crystal x-ray spectrometer. In tandem with a collimating slit, this method reveals a projection of the double differential angular-wavelength spectrum of the ICS radiation in a single shot. The measurements enabled by this diagnostic illustrate the combined off-axis and nonlinear-field-induced redshifting in the ICS emission process. The spectra obtained illustrate in detail the strength of the normalized laser vector potential, and provide a nondestructive measure of the temporal and spatial electron-laser beam overlap.« less

Multi-spectral pyrometer for gas turbine blade temperature measurement

NASA Astrophysics Data System (ADS)

Gao, Shan; Wang, Lixin; Feng, Chi

2014-09-01

To achieve the highest possible turbine inlet temperature requires to accurately measuring the turbine blade temperature. If the temperature of blade frequent beyond the design limits, it will seriously reduce the service life. The problem for the accuracy of the temperature measurement includes the value of the target surface emissivity is unknown and the emissivity model is variability and the thermal radiation of the high temperature environment. In this paper, the multi-spectral pyrometer is designed provided mainly for range 500-1000°, and present a model corrected in terms of the error due to the reflected radiation only base on the turbine geometry and the physical properties of the material. Under different working conditions, the method can reduce the measurement error from the reflect radiation of vanes, make measurement closer to the actual temperature of the blade and calculating the corresponding model through genetic algorithm. The experiment shows that this method has higher accuracy measurements.

Temporal measurement on and using pulses from spectrally narrowed emission in styrylpyridinium cyanine dye

NASA Astrophysics Data System (ADS)

Dharmadhikari, Aditya K.; Bhowmik, Achintya K.; Ahyi, Ayayi C.; Thakur, Mrinal

2001-11-01

Highly efficient spectrally narrowed emission (SNE) was observed in the solution of strylpyridinium cyanine dye (SPCD) pumped by fundamental and second harmonic of a picosecond Nd:YAG laser in two separate arrangements. A highly directional emission was observed in both the pumping arrangements without incorporating any mirrors. The pulse duration of the SNE was measured by background free SHG intensity autocorrelation technique. The measured duration of the pulses was 40 ps. These pulses, having a spectral linewidth of 10 nm (full width at half maximum), were used as a probe to measure the transient changes in the transmission in SPCD solution using a pump-probe setup. The transient optical transmission indicated a gain at the overlap and no gain was observed beyond a delay of 40 ps.

Spectral characterization of surface emissivities in the thermal infrared

NASA Astrophysics Data System (ADS)

Niclòs, Raquel; Mira, Maria; Valor, Enric; Caselles, Diego; García-Santos, Vicente; Caselles, Vicente; Sánchez, Juan M.

2015-04-01

Thermal infrared (TIR) remote sensing trends to hyperspectral sensors on board satellites in the last decades, e.g., the current EOS-MODIS and EOS-ASTER and future missions like HyspIRI, ECOSTRESS, THIRSTY and MISTIGRI. This study aims to characterize spectrally the emissive properties of several surfaces, mostly soils. A spectrometer ranging from 2 to 16 μm, D&P Model 102, has been used to measure samples with singular spectral features, e.g. a sandy soil rich in gypsum sampled in White Sands (New Mexico, USA), salt samples, powdered quartz, and powdered calcite. These samples were chosen for their role in the assessment of thermal emissivity of soils, e.g., the calcite and quartz contents are key variables for modeling TIR emissivities of bare soils, along with soil moisture and organic matter. Additionally, the existence of large areas in the world with abundance of these materials, some of them used for calibration/validation activities of satellite sensors and products, makes the chosen samples interesting. White Sands is the world's largest gypsum dune field encompassing 400 km^2; the salt samples characterize the Salar of Uyuni (Bolivia), the largest salt flat in the world (up to 10,000 km^2), as well as the Jordanian and Israeli salt evaporation ponds at the south end of the Dead Sea, or the evaporation lagoons in Aigües-Mortes (France); and quartz is omnipresent in most of the arid regions of the world such as the Algodones Dunes or Kelso Dunes (California, USA), with areas around 700 km2 and 120 km^2, respectively. Measurements of target leaving radiance, hemispherical radiance reflected by a diffuse reflectance panel, and the radiance from a black body at different temperatures were taken to obtain thermal spectra with the D&P spectrometer. The good consistency observed between our measurements and laboratory spectra of similar samples (ASTER and MODIS spectral libraries) indicated the validity of the measurement protocol. Further, our study showed the

Highly-Damped Spectral Acceleration as a Ground Motion Intensity Measure for Estimating Collapse Vulnerability of Buildings

NASA Astrophysics Data System (ADS)

Buyco, K.; Heaton, T. H.

2016-12-01

Current U.S. seismic code and performance-based design recommendations quantify ground motion intensity using 5%-damped spectral acceleration when estimating the collapse vulnerability of buildings. This intensity measure works well for predicting inter-story drift due to moderate shaking, but other measures have been shown to be better for estimating collapse risk.We propose using highly-damped (>10%) spectral acceleration to assess collapse vulnerability. As damping is increased, the spectral acceleration at a given period T begins to behave like a weighted average of the corresponding lowly-damped (i.e. 5%) spectrum at a range of periods. Weights for periods longer than T increase as damping increases. Using high damping is physically intuitive for two reasons. Firstly, ductile buildings dissipate a large amount of hysteretic energy before collapse and thus behave more like highly-damped systems. Secondly, heavily damaged buildings experience period-lengthening, giving further credence to the weighted-averaging property of highly-damped spectral acceleration.To determine the optimal damping value(s) for this ground motion intensity measure, we conduct incremental dynamic analysis for a suite of ground motions on several different mid-rise steel buildings and select the damping value yielding the lowest dispersion of intensity at the collapse threshold. Spectral acceleration calculated with damping as high as 70% has been shown to be a better indicator of collapse than that with 5% damping.

Absolute radiant power measurement for the Au M lines of laser-plasma using a calibrated broadband soft X-ray spectrometer with flat-spectral response.

PubMed

Troussel, Ph; Villette, B; Emprin, B; Oudot, G; Tassin, V; Bridou, F; Delmotte, F; Krumrey, M

2014-01-01

CEA implemented an absolutely calibrated broadband soft X-ray spectrometer called DMX on the Omega laser facility at the Laboratory for Laser Energetics (LLE) in 1999 to measure radiant power and spectral distribution of the radiation of the Au plasma. The DMX spectrometer is composed of 20 channels covering the spectral range from 50 eV to 20 keV. The channels for energies below 1.5 keV combine a mirror and a filter with a coaxial photo-emissive detector. For the channels above 5 keV the photoemissive detector is replaced by a conductive detector. The intermediate energy channels (1.5 keV < photon energy < 5 keV) use only a filter and a coaxial detector. A further improvement of DMX consists in flat-response X-ray channels for a precise absolute measurement of the photon flux in the photon energy range from 0.1 keV to 6 keV. Such channels are equipped with a filter, a Multilayer Mirror (MLM), and a coaxial detector. We present as an example the development of channel for the gold M emission lines in the photon energy range from 2 keV to 4 keV which has been successfully used on the OMEGA laser facility. The results of the radiant power measurements with the new MLM channel and with the usual channel composed of a thin titanium filter and a coaxial detector (without mirror) are compared. All elements of the channel have been calibrated in the laboratory of the Physikalisch-Technische Bundesanstalt, Germany's National Metrology Institute, at the synchrotron radiation facility BESSY II in Berlin using dedicated well established and validated methods.

Enabling three-dimensional densitometric measurements using laboratory source X-ray micro-computed tomography

NASA Astrophysics Data System (ADS)

Pankhurst, M. J.; Fowler, R.; Courtois, L.; Nonni, S.; Zuddas, F.; Atwood, R. C.; Davis, G. R.; Lee, P. D.

2018-01-01

We present new software allowing significantly improved quantitative mapping of the three-dimensional density distribution of objects using laboratory source polychromatic X-rays via a beam characterisation approach (c.f. filtering or comparison to phantoms). One key advantage is that a precise representation of the specimen material is not required. The method exploits well-established, widely available, non-destructive and increasingly accessible laboratory-source X-ray tomography. Beam characterisation is performed in two stages: (1) projection data are collected through a range of known materials utilising a novel hardware design integrated into the rotation stage; and (2) a Python code optimises a spectral response model of the system. We provide hardware designs for use with a rotation stage able to be tilted, yet the concept is easily adaptable to virtually any laboratory system and sample, and implicitly corrects the image artefact known as beam hardening.

The Research of Correlation of Water Surface Spectral and Sediment Parameters

NASA Astrophysics Data System (ADS)

Li, J.; Gong, G.; Fang, W.; Sun, W.

2018-04-01

In the method of survey underwater topography using remote sensing, and the water surface spectral reflectance R, which remote sensing inversion results were closely related to affects by the water and underwater sediment and other aspects, especially in shallow nearshore coastal waters, different sediment types significantly affected the reflectance changes. Therefore, it was of great significance of improving retrieval accuracy to explore the relation of sediment and water surface spectral reflectance. In this study, in order to explore relationship, we used intertidal sediment sand samples in Sheyang estuary, and in the laboratory measured and calculated the chroma indicators, and the water surface spectral reflectance. We found that water surface spectral reflectance had a high correlation with the chroma indicators; research result stated that the color of the sediment had an very important impact on the water surface spectral, especially in Red-Green chroma a*. Also, the research determined the sensitive spectrum bands of the Red-Green chroma a*, which were 636-617 nm, 716-747 nm and 770-792 nm.

RIS4E at Kilauea's December 1974 Flow: Chemical, mineralogical and spectral characteristics of Hawaiian basaltic alteration products measured with portable instruments

NASA Astrophysics Data System (ADS)

Young, K. E.; Rogers, D.; Dyar, M. D.; Ito, G.; Yant, M.; McAdam, A.; Bleacher, J. E.; Glotch, T. D.

2015-12-01

A major objective of the SSERVI RIS4E (Remote, In-situ, and Synchrotron Studies for Science and Exploration) investigation is to evaluate the performance of portable chemical and mineralogical instruments in a variety of planetary volcanic analog settings. To that end, we used a suite of true/proxy portable instruments (XRF, LIBS, XRD, near-IR and mid-IR spectrometers), to measure the chemical and spectral characteristics of young basaltic flows (erupted December 1974, or D1974) within the southwest rift zone of Kilauea, Hawaii. The D1974 lavas exhibit multiple flow morphologies and textures, and have undergone alteration by a variety of processes, including acid weathering, oxidation and devitrification. The mineralogy, chemistry and infrared spectral properties of select samples from these altered surfaces have been well characterized by previous groups using high resolution (e.g. SEM, TEM) and/or laboratory measurements (XRD, Mossbauer, infrared). Typical alteration products include coatings of Fe-Ti-oxide +/- an overlying silica-rich coating. Coatings are commonly discontinuous and vary in color. Oxidation fronts are also present, most visible as reddish brown discoloration along the edges of broken and uplifted flow crusts. The previous detailed characterizations provide the basis for evaluating instrument performance and also allow us to assess areas where portable instruments can contribute new information to current understanding. These areas include characterizing the spatial variability in alteration chemistry/mineralogy, relating chemical/mineralogical properties to texture and context, and comparing chemical/mineralogical variations with infrared spectral properties. Because infrared spectra are commonly used to assess compositional variations of a site remotely, either from the ground or from orbit, relating changes in chemistry and mineralogy to spectral variations is particularly important. Last, the D1974 site provides an excellent location to test

Safety in the Chemical Laboratory: Laboratory Air Quality: Part II. Measurements of Ventilation Rates.

ERIC Educational Resources Information Center

Butcher, Samuel S.; And Others

1985-01-01

Part I of this paper (SE 538 295) described a simple model for estimating laboratory concentrations of gas phase pollutants. In this part, the measurement of ventilation rates and applications of the model are discussed. The model can provide a useful starting point in planning for safer instructional laboratories. (JN)

Spectral signatures of polar stratospheric clouds and sulfate aerosol

NASA Technical Reports Server (NTRS)

Massie, S. T.; Bailey, P. L.; Gille, J. C.; Lee, E. C.; Mergenthaler, J. L.; Roche, A. E.; Kumer, J. B.; Fishbein, E. F.; Waters, J. W.; Lahoz, W. A.

1994-01-01

Multiwavelength observations of Antarctic and midlatitude aerosol by the Cryogenic Limb Array Etalon Spectrometer (CLAES) experiment on the Upper Atmosphere Research Satellite (UARS) are used to demonstrate a technique that identifies the location of polar stratospheric clouds. The technique discussed uses the normalized area of the triangle formed by the aerosol extinctions at 925, 1257, and 1605/cm (10.8, 8.0, and 6.2 micrometers) to derive a spectral aerosol measure M of the aerosol spectrum. Mie calculations for spherical particles and T-matrix calculations for spheriodal particles are used to generate theoretical spectral extinction curves for sulfate and polar stratospheric cloud particles. The values of the spectral aerosol measure M for the sulfate and polar stratospheric cloud particles are shown to be different. Aerosol extinction data, corresponding to temperatures between 180 and 220 K at a pressure of 46 hPa (near 21-km altitude) for 18 August 1992, are used to demonstrate the technique. Thermodynamic calculations, based upon frost-point calculations and laboratory phase-equilibrium studies of nitric acid trihydrate, are used to predict the location of nitric acid trihydrate cloud particles.

Laboratory measurements and astronomical search for the HSO radical

NASA Astrophysics Data System (ADS)

Cazzoli, Gabriele; Lattanzi, Valerio; Kirsch, Till; Gauss, Jürgen; Tercero, Belén; Cernicharo, José; Puzzarini, Cristina

2016-06-01

Context. Despite the fact that many sulfur-bearing molecules, ranging from simple diatomic species up to astronomical complex molecules, have been detected in the interstellar medium, the sulfur chemistry in space is largely unknown and a depletion in the abundance of S-containing species has been observed in the cold, dense interstellar medium. The chemical form of the missing sulfur has yet to be identified. Aims: For these reasons, in view of the fact that there is a large abundance of triatomic species harbouring sulfur, oxygen, and hydrogen, we decided to investigate the HSO radical in the laboratory to try its astronomical detection. Methods: High-resolution measurements of the rotational spectrum of the HSO radical were carried out within a frequency range well up into the THz region. Subsequently, a rigorous search for HSO in the two most studied high-mass star-forming regions, Orion KL and Sagittarius (Sgr) B2, and in the cold dark cloud Barnard 1 (B1-b) was performed. Results: The frequency coverage and the spectral resolution of our measurements allowed us to improve and extend the existing dataset of spectroscopic parameters, thus enabling accurate frequency predictions up to the THz range. These were used to derive the synthetic spectrum of HSO, by means of the MADEX code, according to the physical parameters of the astronomical source under consideration. For all sources investigated, the lack of HSO lines above the confusion limit of the data is evident. Conclusions: The derived upper limit to the abundance of HSO clearly indicates that this molecule does not achieve significant abundances in either the gas phase or in the ice mantles of dust grains. This paper makes use of the following ALMA data: ADS/JAO.ALMA#2011.0.00009.SV. ALMA is a partnership of ESO (representing its member states), NSF (USA), and NINS (Japan) with NRC (Canada), NSC, and ASIAA (Taiwan), and KASI (Republic of Korea), in cooperation with the Republic of Chile. The Joint ALMA

Laboratory measurements of radiance and reflectance spectra of dilute secondary-treated sewage sludge

NASA Technical Reports Server (NTRS)

Witte, W. G.; Usry, J. W.; Whitlock, C. H.; Gurganus, E. A.

1977-01-01

The National Aeronautics and Space Administration (NASA), in cooperation with the Environmental Protection Agency (EPA) and the National Oceanic and Atmospheric Administration (NOAA), conducted a research program to evaluate the feasibility of remotely monitoring ocean dumping of waste products such as acid and sewage sludge. One aspect of the research program involved the measurements of upwelled spectral signatures for sewage-sludge mixtures of different concentrations in an 11600-liter tank. This paper describes the laboratory arrangement and presents radiance and reflectance spectra in the visible and near-infrared ranges for concentrations ranging from 9.7 to 180 ppm of secondary-treated sewage sludge mixed with two types of base water. Results indicate that upwelled radiance varies in a near-linear manner with concentration and that the sludge has a practically flat signal response between 420 and 970 nm. Reflectance spectra were obtained for the sewage-sludge mixtures at all wavelengths and concentrations.

Measuring meaningful learning in the undergraduate chemistry laboratory

NASA Astrophysics Data System (ADS)

Galloway, Kelli R.

The undergraduate chemistry laboratory has been an essential component in chemistry education for over a century. The literature includes reports on investigations of singular aspects laboratory learning and attempts to measure the efficacy of reformed laboratory curriculum as well as faculty goals for laboratory learning which found common goals among instructors for students to learn laboratory skills, techniques, experimental design, and to develop critical thinking skills. These findings are important for improving teaching and learning in the undergraduate chemistry laboratory, but research is needed to connect the faculty goals to student perceptions. This study was designed to explore students' ideas about learning in the undergraduate chemistry laboratory. Novak's Theory of Meaningful Learning was used as a guide for the data collection and analysis choices for this research. Novak's theory states that in order for meaningful learning to occur the cognitive, affective, and psychomotor domains must be integrated. The psychomotor domain is inherent in the chemistry laboratory, but the extent to which the cognitive and affective domains are integrated is unknown. For meaningful learning to occur in the laboratory, students must actively integrate both the cognitive domain and the affective domains into the "doing" of their laboratory work. The Meaningful Learning in the Laboratory Instrument (MLLI) was designed to measure students' cognitive and affective expectations and experiences within the context of conducting experiments in the undergraduate chemistry laboratory. Evidence for the validity and reliability of the data generated by the MLLI were collected from multiple quantitative studies: a one semester study at one university, a one semester study at 15 colleges and universities across the United States, and a longitudinal study where the MLLI was administered 6 times during two years of general and organic chemistry laboratory courses. Results from

Relationships Among Peripheral and Central Electrophysiological Measures of Spatial and Spectral Selectivity and Speech Perception in Cochlear Implant Users.

PubMed

Scheperle, Rachel A; Abbas, Paul J

2015-01-01

The ability to perceive speech is related to the listener's ability to differentiate among frequencies (i.e., spectral resolution). Cochlear implant (CI) users exhibit variable speech-perception and spectral-resolution abilities, which can be attributed in part to the extent of electrode interactions at the periphery (i.e., spatial selectivity). However, electrophysiological measures of peripheral spatial selectivity have not been found to correlate with speech perception. The purpose of this study was to evaluate auditory processing at the periphery and cortex using both simple and spectrally complex stimuli to better understand the stages of neural processing underlying speech perception. The hypotheses were that (1) by more completely characterizing peripheral excitation patterns than in previous studies, significant correlations with measures of spectral selectivity and speech perception would be observed, (2) adding information about processing at a level central to the auditory nerve would account for additional variability in speech perception, and (3) responses elicited with spectrally complex stimuli would be more strongly correlated with speech perception than responses elicited with spectrally simple stimuli. Eleven adult CI users participated. Three experimental processor programs (MAPs) were created to vary the likelihood of electrode interactions within each participant. For each MAP, a subset of 7 of 22 intracochlear electrodes was activated: adjacent (MAP 1), every other (MAP 2), or every third (MAP 3). Peripheral spatial selectivity was assessed using the electrically evoked compound action potential (ECAP) to obtain channel-interaction functions for all activated electrodes (13 functions total). Central processing was assessed by eliciting the auditory change complex with both spatial (electrode pairs) and spectral (rippled noise) stimulus changes. Speech-perception measures included vowel discrimination and the Bamford-Kowal-Bench Speech

Relationships Among Peripheral and Central Electrophysiological Measures of Spatial and Spectral Selectivity and Speech Perception in Cochlear Implant Users

PubMed Central

Scheperle, Rachel A.; Abbas, Paul J.

2014-01-01

Objectives The ability to perceive speech is related to the listener’s ability to differentiate among frequencies (i.e., spectral resolution). Cochlear implant (CI) users exhibit variable speech-perception and spectral-resolution abilities, which can be attributed in part to the extent of electrode interactions at the periphery (i.e., spatial selectivity). However, electrophysiological measures of peripheral spatial selectivity have not been found to correlate with speech perception. The purpose of this study was to evaluate auditory processing at the periphery and cortex using both simple and spectrally complex stimuli to better understand the stages of neural processing underlying speech perception. The hypotheses were that (1) by more completely characterizing peripheral excitation patterns than in previous studies, significant correlations with measures of spectral selectivity and speech perception would be observed, (2) adding information about processing at a level central to the auditory nerve would account for additional variability in speech perception, and (3) responses elicited with spectrally complex stimuli would be more strongly correlated with speech perception than responses elicited with spectrally simple stimuli. Design Eleven adult CI users participated. Three experimental processor programs (MAPs) were created to vary the likelihood of electrode interactions within each participant. For each MAP, a subset of 7 of 22 intracochlear electrodes was activated: adjacent (MAP 1), every-other (MAP 2), or every third (MAP 3). Peripheral spatial selectivity was assessed using the electrically evoked compound action potential (ECAP) to obtain channel-interaction functions for all activated electrodes (13 functions total). Central processing was assessed by eliciting the auditory change complex (ACC) with both spatial (electrode pairs) and spectral (rippled noise) stimulus changes. Speech-perception measures included vowel-discrimination and the Bamford

Spectral signature selection for mapping unvegetated soils

NASA Technical Reports Server (NTRS)

May, G. A.; Petersen, G. W.

1975-01-01

Airborne multispectral scanner data covering the wavelength interval from 0.40-2.60 microns were collected at an altitude of 1000 m above the terrain in southeastern Pennsylvania. Uniform training areas were selected within three sites from this flightline. Soil samples were collected from each site and a procedure developed to allow assignment of scan line and element number from the multispectral scanner data to each sampling location. These soil samples were analyzed on a spectrophotometer and laboratory spectral signatures were derived. After correcting for solar radiation and atmospheric attenuation, the laboratory signatures were compared to the spectral signatures derived from these same soils using multispectral scanner data. Both signatures were used in supervised and unsupervised classification routines. Computer-generated maps using the laboratory and multispectral scanner derived signatures resulted in maps that were similar to maps resulting from field surveys. Approximately 90% agreement was obtained between classification maps produced using multispectral scanner derived signatures and laboratory derived signatures.

NREL Solar Radiation Research Laboratory (SRRL): Baseline Measurement System (BMS); Golden, Colorado (Data)

DOE Data Explorer

Stoffel, T.; Andreas, A.

1981-07-15

The SRRL was established at the Solar Energy Research Institute (now NREL) in 1981 to provide continuous measurements of the solar resources, outdoor calibrations of pyranometers and pyrheliometers, and to characterize commercially available instrumentation. The SRRL is an outdoor laboratory located on South Table Mountain, a mesa providing excellent solar access throughout the year, overlooking Denver. Beginning with the basic measurements of global horizontal irradiance, direct normal irradiance and diffuse horizontal irradiance at 5-minute intervals, the SRRL Baseline Measurement System now produces more than 130 data elements at 1-min intervals that are available from the Measurement & Instrumentation Data Center Web site. Data sources include global horizontal, direct normal, diffuse horizontal (from shadowband and tracking disk), global on tilted surfaces, reflected solar irradiance, ultraviolet, infrared (upwelling and downwelling), photometric and spectral radiometers, sky imagery, and surface meteorological conditions (temperature, relative humidity, barometric pressure, precipitation, snow cover, wind speed and direction at multiple levels). Data quality control and assessment include daily instrument maintenance (M-F) with automated data quality control based on real-time examinations of redundant instrumentation and internal consistency checks using NREL's SERI-QC methodology. Operators are notified of equipment problems by automatic e-mail messages generated by the data acquisition and processing system. Radiometers are recalibrated at least annually with reference instruments traceable to the World Radiometric Reference (WRR).

Dynamic measurement of fluorescent proteins spectral distribution on virus infected cells

NASA Astrophysics Data System (ADS)

Lee, Ja-Yun; Wu, Ming-Xiu; Kao, Chia-Yun; Wu, Tzong-Yuan; Hsu, I.-Jen

2006-09-01

We constructed a dynamic spectroscopy system that can simultaneously measure the intensity and spectral distributions of samples with multi-fluorophores in a single scan. The system was used to monitor the fluorescence distribution of cells infected by the virus, which is constructed by a recombinant baculoviruses, vAcD-Rhir-E, containing the red and green fluorescent protein gene that can simultaneously produce dual fluorescence in recombinant virus-infected Spodoptera frugiperda 21 cells (Sf21) under the control of a polyhedrin promoter. The system was composed of an excitation light source, a scanning system and a spectrometer. We also developed an algorithm and fitting process to analyze the pattern of fluorescence distribution of the dual fluorescence produced in the recombinant virus-infected cells. All the algorithm and calculation are automatically processed in a visualized scanning program and can monitor the specific region of sample by calculating its intensity distribution. The spectral measurement of each pixel was performed at millisecond range and the two dimensional distribution of full spectrum was recorded within several seconds. We have constructed a dynamic spectroscopy system to monitor the process of virus-infection of cells. The distributions of the dual fluorescence were simultaneously measured at micrometer resolution.

Laboratory measurements of radiance and reflectance spectra of dilute primary-treated sewage sludge

NASA Technical Reports Server (NTRS)

Usry, J. W.; Witte, W. G.; Whitlock, C. H.; Gurganus, E. A.

1977-01-01

The feasibility of remotely monitoring ocean dumping of waste products such as acid and sewage sludge is evaluated. The laboratory arrangement, solar simulator, and test results from three experiments conducted in the laboratory are described. Radiance and reflectance spectra are presented for primary-treated sewage sludge mixed with two types of base water. Results indicate that upwelled reflectance varies in a near-linear manner with concentration and that the sludge has a practically flat signal response between 420 and 970 nm. Well-defined upwelled reflectance spectra were obtained for the sewage-sludge mixtures at all wavelengths and concentrations. The spectral-reflectance values appeared to be influenced by the type of base water, but this influence was small, especially for the mixtures with low concentrations of sewage sludge.

Spectral reflectances of natural targets for use in remote sensing studies

NASA Technical Reports Server (NTRS)

Bowker, D. E.; Davis, R. E.; Myrick, D. L.; Stacy, K.; Jones, W. T.

1985-01-01

A collection of spectral reflectances of 156 natural targets is presented in a uniform format. For each target both a graphical plot and a digital tabulation of reflectance is given. The data were taken from the literature and include laboratory, field, and aircraft measurements. A discussion of the different measurements of reflectance is given, along with the changes in apparent reflectance when targets are viewed through the atmosphere. The salient features of the reflectance curves of common target types are presented and discussed.

Spectral Remittance and Transmittance of Visible and Infrared-A Radiation in Human Skin-Comparison Between in vivo Measurements and Model Calculations.

PubMed

Piazena, Helmut; Meffert, Hans; Uebelhack, Ralf

2017-11-01

The aim of the study was to assess the interindividual variability of spectral remittance and spectral transmittance of visible and infrared-A radiations interacting with human skin and subcutaneous tissue, and direct measurements were taken in vivo using healthy persons of different skin color types. Up to wavelengths of about 900 nm, both spectral remittance and spectral transmittance depended significantly on the individual contents of melanin and hemoglobin in the skin, whereas the contents of water and lipids mainly determined spectral slopes of both characteristics of interaction for wavelengths above about 900 nm. In vivo measured data of spectral transmittance showed approximately similar decreases with tissue thickness between about 900 nm and 1100 nm as compared with model data which were calculated using spectral absorption and scattering coefficients of skin samples in vitro published by different authors. In addition, in vivo measured data and in vitro-based model calculations of spectral remittance were approximately comparable in this wavelength range. In contrast, systematic but individually varying differences between both methods were found for both spectral remittance and spectral transmittance at wavelengths below about 900 nm, where interaction of radiation was significantly affected by both melanin and hemoglobin. © 2017 The American Society of Photobiology.

Imaging spectrometer measurement of water vapor in the 400 to 2500 nm spectral region

NASA Technical Reports Server (NTRS)

Green, Robert O.; Roberts, Dar A.; Conel, James E.; Dozier, Jeff

1995-01-01

The Airborne Visible-Infrared Imaging Spectrometer (AVIRIS) measures the total upwelling spectral radiance from 400 to 2500 nm sampled at 10 nm intervals. The instrument acquires spectral data at an altitude of 20 km above sea level, as images of 11 by up to 100 km at 17x17 meter spatial sampling. We have developed a nonlinear spectral fitting algorithm coupled with a radiative transfer code to derive the total path water vapor from the spectrum, measured for each spatial element in an AVIRIS image. The algorithm compensates for variation in the surface spectral reflectance and atmospheric aerosols. It uses water vapor absorption bands centered at 940 nm, 1040 nm, and 1380 nm. We analyze data sets with water vapor abundances ranging from 1 to 40 perceptible millimeters. In one data set, the total path water vapor varies from 7 to 21 mm over a distance of less than 10 km. We have analyzed a time series of five images acquired at 12 minute intervals; these show spatially heterogeneous changes of advocated water vapor of 25 percent over 1 hour. The algorithm determines water vapor for images with a range of ground covers, including bare rock and soil, sparse to dense vegetation, snow and ice, open water, and clouds. The precision of the water vapor determination approaches one percent. However, the precision is sensitive to the absolute abundance and the absorption strength of the atmospheric water vapor band analyzed. We have evaluated the accuracy of the algorithm by comparing several surface-based determinations of water vapor at the time of the AVIRIS data acquisition. The agreement between the AVIRIS measured water vapor and the in situ surface radiometer and surface interferometer measured water vapor is 5 to 10 percent.

Measuring preschool learning engagement in the laboratory.

PubMed

Halliday, Simone E; Calkins, Susan D; Leerkes, Esther M

2018-03-01

Learning engagement is a critical factor for academic achievement and successful school transitioning. However, current methods of assessing learning engagement in young children are limited to teacher report or classroom observation, which may limit the types of research questions one could assess about this construct. The current study investigated the validity of a novel assessment designed to measure behavioral learning engagement among young children in a standardized laboratory setting and examined how learning engagement in the laboratory relates to future classroom adjustment. Preschool-aged children (N = 278) participated in a learning-based Tangrams task and Story sequencing task and were observed based on seven behavioral indicators of engagement. Confirmatory factor analysis supported the construct validity for a behavioral engagement factor composed of six of the original behavioral indicators: attention to instructions, on-task behavior, enthusiasm/energy, persistence, monitoring progress/strategy use, and negative affect. Concurrent validity for this behavioral engagement factor was established through its associations with parent-reported mastery motivation and pre-academic skills in math and literacy measured in the laboratory, and predictive validity was demonstrated through its associations with teacher-reported classroom learning behaviors and performance in math and reading in kindergarten. These associations were found when behavioral engagement was observed during both the nonverbal task and the verbal story sequencing tasks and persisted even after controlling for child minority status, gender, and maternal education. Learning engagement in preschool appears to be successfully measurable in a laboratory setting. This finding has implications for future research on the mechanisms that support successful academic development. Copyright © 2017 Elsevier Inc. All rights reserved.

Sensitivity, specificity, and reproducibility of four measures of laboratory turnaround time.

PubMed

Valenstein, P N; Emancipator, K

1989-04-01

The authors studied the performance of four measures of laboratory turnaround time: the mean, median, 90th percentile, and proportion of tests reported within a predetermined cut-off interval (proportion of acceptable tests [PAT]). Measures were examined with the use of turnaround time data from 11,070 stat partial thromboplastin times, 16,761 urine cultures, and 28,055 stat electrolyte panels performed by a single laboratory. For laboratories with long turnaround times, the most important quality of a turnaround time measure is high reproducibility, so that improvement in reporting speed can be distinguished from random variation resulting from sampling. The mean was found to be the most reproducible of the four measures, followed by the median. The mean achieved acceptable precision with sample sizes of 100-500 tests. For laboratories with normally rapid turnaround times, the most important quality of a measure is high sensitivity and specificity for detecting whether turnaround time has dropped below standards. The PAT was found to be the best measure of turnaround time in this setting but required sample sizes of at least 500 tests to achieve acceptable accuracy. Laboratory turnaround time may be measured for different reasons. The method of measurement should be chosen with an eye toward its intended application.

High-resolution grazing-incidence grating spectrometer for temperature measurements of low-Z ions emitting in the 100-300 Å spectral banda)

NASA Astrophysics Data System (ADS)

Widmann, K.; Beiersdorfer, P.; Magee, E. W.; Boyle, D. P.; Kaita, R.; Majeski, R.

2014-11-01

We have constructed a high-resolution grazing-incidence spectrometer designed for measuring the ion temperature of low-Z elements, such as Li+ or Li2 +, which radiate near 199 Å and 135 Å, respectively. Based on measurements at the Livermore Electron Beam Ion Trap we have shown that the instrumental resolution is better than 48 mÅ at the 200 Å setting and better than 40 mÅ for the 135-Å range. Such a high spectral resolution corresponds to an instrumental limit for line-width based temperature measurements of about 45 eV for the 199 Å Li+ and 65 eV for the 135 Å Li2 + lines. Recently obtained survey spectra from the Lithium Tokamak Experiment at the Princeton Plasma Physics Laboratory show the presence of these lithium emission lines and the expected core ion temperature of approximately 70 eV is sufficiently high to demonstrate the feasibility of utilizing our high-resolution spectrometer as an ion-temperature diagnostic.

Ionizing laser propagation and spectral phase determination

NASA Astrophysics Data System (ADS)

Mittelberger, D. E.; Nakamura, K.; Lehe, R.; Gonsalves, A. J.; Benedetti, C.; Mao, H.-S.; Daniels, J.; Dale, N.; Swanson, K. K.; Esarey, E.; Leemans, W. P.

2017-03-01

Ionization-induced blueshifting is investigated through INF&RNO simulations and experimental studies at the Berkeley Laboratory Laser Accelerator (BELLA) Center. The effects of spectral phase and optical compression are explored. An in-situ method for verifying the spectral phase of an intense laser pulse at focus is presented, based on the effects of optical compression on the morphology of the blueshifted laser spectra.

[Nitrogen stress measurement of canola based on multi-spectral charged coupled device imaging sensor].

PubMed

Feng, Lei; Fang, Hui; Zhou, Wei-Jun; Huang, Min; He, Yong

2006-09-01

Site-specific variable nitrogen application is one of the major precision crop production management operations. Obtaining sufficient crop nitrogen stress information is essential for achieving effective site-specific nitrogen applications. The present paper describes the development of a multi-spectral nitrogen deficiency sensor, which uses three channels (green, red, near-infrared) of crop images to determine the nitrogen level of canola. This sensor assesses the nitrogen stress by means of estimated SPAD value of the canola based on canola canopy reflectance sensed using three channels (green, red, near-infrared) of the multi-spectral camera. The core of this investigation is the calibration methods between the multi-spectral references and the nitrogen levels in crops measured using a SPAD 502 chlorophyll meter. Based on the results obtained from this study, it can be concluded that a multi-spectral CCD camera can provide sufficient information to perform reasonable SPAD values estimation during field operations.

Spectral domain phase microscopy: a new tool for measuring cellular dynamics and cytoplasmic flow

NASA Astrophysics Data System (ADS)

McDowell, Emily J.; Choma, Michael A.; Ellerbee, Audrey K.; Izatt, Joseph A.

2005-03-01

Broadband interferometry is an attractive technique for the detection of cellular motions because it provides depth-resolved interferometric phase information via coherence gating. Here a phase sensitive technique called spectral domain phase microscopy (SDPM) is presented. SDPM is a functional extension of spectral domain optical coherence tomography that allows for the detection of cellular motions and dynamics with nanometer-scale sensitivity. This sensitivity is made possible by the inherent phase stability of spectral domain OCT combined with common-path interferometry. The theory that underlies this technique is presented, the sensitivity of the technique is demonstrated by the measurement of the thermal expansion coefficient of borosilicate glass, and the response of an Amoeba proteus to puncture of its cell membrane is measured. We also exploit the phase stability of SDPM to perform Doppler flow imaging of cytoplasmic streaming in A. proteus. We show reversal of cytoplasmic flow in response to stimuli, and we show that the cytoplasmic flow is laminar (i.e. parabolic) in nature. We are currently investigating the use of SDPM in a variety of different cell types.

Atmospheric Temperature Profile Measurements Using Mobile High Spectral Resolution Lidar

NASA Astrophysics Data System (ADS)

Razenkov, Ilya I.; Eloranta, Edwin W.

2016-06-01

The High Spectral Resolution Lidar (HSRL) designed at the University of Wisconsin-Madison discriminates between Mie and Rayleigh backscattering [1]. It exploits the Doppler effect caused by thermal motion of molecules, which broadens the spectrum of the transmitted laser light. That allows for absolute calibration of the lidar and measurements of the aerosol volume backscatter coefficient. Two iodine absorption filters with different absorption line widths (a regular iodine vapor filter and Argon buffered iodine filter) allow for atmospheric temperature profile measurements. The sensitivity of the measured signal-to-air temperature ratio is around 0.14%/K. The instrument uses a shared telescope transmitter-receiver design and operates in eyesafe mode (the product of laser average power and telescope aperture equals 0.1 Wm2 at 532 nm).

Solar Spectral Irradiance at 782 nm as Measured by the SES Sensor Onboard Picard

NASA Astrophysics Data System (ADS)

Meftah, M.; Hauchecorne, A.; Irbah, A.; Cessateur, G.; Bekki, S.; Damé, L.; Bolsée, D.; Pereira, N.

2016-04-01

Picard is a satellite dedicated to the simultaneous measurement of the total and solar spectral irradiance, the solar diameter, the solar shape, and to the Sun's interior through the methods of helioseismology. The satellite was launched on June 15, 2010, and pursued its data acquisitions until March 2014. A Sun Ecartometry Sensor (SES) was developed to provide the stringent pointing requirements of the satellite. The SES sensor produced an image of the Sun at 782 ± 2.5 nm. From the SES data, we obtained a new time series of the solar spectral irradiance at 782 nm from 2010 to 2014. During this period of Solar Cycle 24, the amplitude of the changes has been of the order of ± 0.08 %, corresponding to a range of about 2× 10^{-3} W m^{-2} nm^{-1}. SES observations provided a qualitatively consistent evolution of the solar spectral irradiance variability at 782 nm. SES data show similar amplitude variations with the semi-empirical model Spectral And Total Irradiance REconstruction for the Satellite era (SATIRE-S), whereas the Spectral Irradiance Monitor instrument (SIM) onboard the SOlar Radiation and Climate Experiment satellite (SORCE) highlights higher amplitudes.

Film thickness measurement based on nonlinear phase analysis using a Linnik microscopic white-light spectral interferometer.

PubMed

Guo, Tong; Chen, Zhuo; Li, Minghui; Wu, Juhong; Fu, Xing; Hu, Xiaotang

2018-04-20

Based on white-light spectral interferometry and the Linnik microscopic interference configuration, the nonlinear phase components of the spectral interferometric signal were analyzed for film thickness measurement. The spectral interferometric signal was obtained using a Linnik microscopic white-light spectral interferometer, which includes the nonlinear phase components associated with the effective thickness, the nonlinear phase error caused by the double-objective lens, and the nonlinear phase of the thin film itself. To determine the influence of the effective thickness, a wavelength-correction method was proposed that converts the effective thickness into a constant value; the nonlinear phase caused by the effective thickness can then be determined and subtracted from the total nonlinear phase. A method for the extraction of the nonlinear phase error caused by the double-objective lens was also proposed. Accurate thickness measurement of a thin film can be achieved by fitting the nonlinear phase of the thin film after removal of the nonlinear phase caused by the effective thickness and by the nonlinear phase error caused by the double-objective lens. The experimental results demonstrated that both the wavelength-correction method and the extraction method for the nonlinear phase error caused by the double-objective lens improve the accuracy of film thickness measurements.

A differential spectral responsivity measurement system constructed for determining of the spectral responsivity of a single- and triple-junction photovoltaic cells

NASA Astrophysics Data System (ADS)

Sametoglu, Ferhat; Celikel, Oguz; Witt, Florian

2017-10-01

A differential spectral responsivity (DSR) measurement system has been designed and constructed at National Metrology Institute of Turkey (TUBITAK UME) to determine the spectral responsivity (SR) of a single- or a multi-junction photovoltaic device (solar cell). The DSR setup contains a broad band light bias source composed of a constructed Solar Simulator based on a 1000 W Xe-arc lamp owning a AM-1.5 filter and 250 W quartz-tungsten-halogen lamp, a designed and constructed LED-based Bias Light Sources, a DC voltage bias circuit, and a probe beam optical power tracking and correction circuit controlled with an ADuC847 microcontroller card together with an embedded C based software, designed and constructed in TUBITAK UME under this project. By using the constructed DSR measurement system, the SR calibration of solar cells, the monolitic triple-junction solar cell GaInP/GaInAs/Ge and its corresponding component cells have been performed within the EURAMET Joint Research Project SolCell.

Assessing the role of spectral and intensity cues in spectral ripple detection and discrimination in cochlear-implant users.

PubMed

Anderson, Elizabeth S; Oxenham, Andrew J; Nelson, Peggy B; Nelson, David A

2012-12-01

Measures of spectral ripple resolution have become widely used psychophysical tools for assessing spectral resolution in cochlear-implant (CI) listeners. The objective of this study was to compare spectral ripple discrimination and detection in the same group of CI listeners. Ripple detection thresholds were measured over a range of ripple frequencies and were compared to spectral ripple discrimination thresholds previously obtained from the same CI listeners. The data showed that performance on the two measures was correlated, but that individual subjects' thresholds (at a constant spectral modulation depth) for the two tasks were not equivalent. In addition, spectral ripple detection was often found to be possible at higher rates than expected based on the available spectral cues, making it likely that temporal-envelope cues played a role at higher ripple rates. Finally, spectral ripple detection thresholds were compared to previously obtained speech-perception measures. Results confirmed earlier reports of a robust relationship between detection of widely spaced ripples and measures of speech recognition. In contrast, intensity difference limens for broadband noise did not correlate with spectral ripple detection measures, suggesting a dissociation between the ability to detect small changes in intensity across frequency and across time.

Assessing the role of spectral and intensity cues in spectral ripple detection and discrimination in cochlear-implant users

PubMed Central

Anderson, Elizabeth S.; Oxenham, Andrew J.; Nelson, Peggy B.; Nelson, David A.

2012-01-01

Measures of spectral ripple resolution have become widely used psychophysical tools for assessing spectral resolution in cochlear-implant (CI) listeners. The objective of this study was to compare spectral ripple discrimination and detection in the same group of CI listeners. Ripple detection thresholds were measured over a range of ripple frequencies and were compared to spectral ripple discrimination thresholds previously obtained from the same CI listeners. The data showed that performance on the two measures was correlated, but that individual subjects’ thresholds (at a constant spectral modulation depth) for the two tasks were not equivalent. In addition, spectral ripple detection was often found to be possible at higher rates than expected based on the available spectral cues, making it likely that temporal-envelope cues played a role at higher ripple rates. Finally, spectral ripple detection thresholds were compared to previously obtained speech-perception measures. Results confirmed earlier reports of a robust relationship between detection of widely spaced ripples and measures of speech recognition. In contrast, intensity difference limens for broadband noise did not correlate with spectral ripple detection measures, suggesting a dissociation between the ability to detect small changes in intensity across frequency and across time. PMID:23231122

Normalized spectral damage of a linear system over different spectral loading patterns

NASA Astrophysics Data System (ADS)

Kim, Chan-Jung

2017-08-01

Spectral fatigue damage is affected by different loading patterns; the damage may be accumulated in a different manner because the spectral pattern has an influence on stresses or strains. The normalization of spectral damage with respect to spectral loading acceleration is a novel solution to compare the accumulated fatigue damage over different spectral loading patterns. To evaluate the sensitivity of fatigue damage over different spectral loading cases, a simple notched specimen is used to conduct a uniaxial vibration test for two representative spectral patterns-random and harmonic-between 30 and 3000 Hz. The fatigue damage to the simple specimen is analyzed for different spectral loading cases using the normalized spectral damage from the measured response data for both acceleration and strain. The influence of spectral loading patterns is discussed based on these analyses.

Laboratory Measurements Of Charge-exchange Produced X-ray Emission From K-shell Transitions In Hydrogenic And Helium-like Fe

NASA Astrophysics Data System (ADS)

Brown, Gregory V.; Beiersdorfer, P.; Boyce, K. R.; Chen, H.; Gu, M. F.; Kelley, R. L.; Kilbourne, C. A.; Porter, F. S.; Thorn, D.; Wargelin, B.

2006-09-01

We have used a microcalorimeter and solid state detectors to measure x-ray emission produced by charge exchange reactions between bare and hydrogenic Fe colliding with neutral helium, hydrogen, and nitrogen gas. We show the measured spectral signature produced by different neutral donors and compare our results to theory where available. We also compare our results to measurements of the Fe K line emission from the Galactic Center measured by the XIS on the Suzaku x-ray observatory. This comparison shows that charge exchange recombination between highly charged ions (either cosmic rays or thermal ions) and neutral gas is probably not the dominant source of diffuse line emission in the Galactic Center. This work was performed under the auspices of the U.S. Department of Energy by University of California, Lawrence Livermore National Laboratory under Contract W-7405-Eng-48, and is also supported by NASA APRA grants to LLNL, GSFC, Harvard-Smithsonian CfA, and Stanford University.

Airborne spectral measurements of surface-atmosphere anisotropy during the SCAR-A, Kuwait oil fire, and TARFOX experiments

NASA Astrophysics Data System (ADS)

Soulen, Peter F.; King, Michael D.; Tsay, Si-Chee; Arnold, G. Thomas; Li, Jason Y.

2000-04-01

During the SCAR-A, Kuwait Oil Fire Smoke Experiment, and TARFOX deployments, angular distributions of spectral reflectance for various surfaces were measured using the scanning Cloud Absorption Radiometer (CAR) mounted on the nose of the University of Washington C-131A research aircraft. The CAR contains 13 narrowband spectral channels between 0.47 and 2.3 μm with a 190° scan aperture (5° before zenith to 5° past nadir) and 1° instantaneous field of view. The bidirectional reflectance is obtained by flying a clockwise circular orbit above the surface, resulting in a ground track approximately 3 km in diameter within about 2 min. Spectral bidirectional reflectances of four surfaces are presented: the Great Dismal Swamp in Virginia with overlying haze layer, the Saudi Arabian Desert and the Persian Gulf in the Middle East, and the Atlantic Ocean measured east of Richmond, Virginia. Although the CAR measurements are contaminated by atmospheric effects, results show distinct spectral characteristics for various types of surface-atmosphere systems, including hot spots, limb brightening and darkening, and Sun glint. In addition, the hemispherical albedo of each surface-atmosphere system is calculated directly by integrating over all high angular-resolution CAR measurements for each spectral channel. Comparing the nadir reflectance with the overall hemispherical albedo of each surface, we find that using nadir reflectances as a surrogate for hemispherical albedo can cause albedos to be underestimated by as much as 95% and overestimated by up to 160%, depending on the type of surface and solar zenith angle.

3D printed miniaturized spectral system for tissue fluorescence lifetime measurements

NASA Astrophysics Data System (ADS)

Zou, Luwei; Mahmoud, Mohamad; Fahs, Mehdi; Liu, Rui; Lo, Joe F.

2016-04-01

Various types of collagens, e.g. type I and III, represent the main load-bearing components in biological tissues. Their composition changes during processes like wound healing and fibrosis. Collagens exhibit autofluorescence when excited by ultra-violet light, distinguishable by their unique fluorescent lifetimes across a range of emission wavelengths. Therefore, we designed a miniaturized spectral-lifetime detection system for collagens as a non-invasive probe for monitoring tissue in wound healing and scarring applications. A sine modulated LED illumination was applied to enable frequency domain (FD) fluorescence lifetime measurements under different wavelengths bands, separated via a series of longpass dichroics at 387nm, 409nm and 435nm. To achieve the minute scale of optomechanics, we employed a stereolithography based 3D printer with <50 μm resolution to create a custom designed optical mount in a hand-held form factor. We examined the characteristics of the 3D printed optical system with finite element modeling to simulate the effect of thermal (LED) and mechanical (handling) strain on the optical system. Using this device, the phase shift and demodulation of collagen types were measured, where the separate spectral bands enhanced the differentiation of their lifetimes.

A detailed characterization of the Saharan dust collected during the Fennec campaign in 2011: in situ ground-based and laboratory measurements

NASA Astrophysics Data System (ADS)

Rocha-Lima, Adriana; Vanderlei Martins, J.; Remer, Lorraine A.; Todd, Martin; Marsham, John H.; Engelstaedter, Sebastian; Ryder, Claire L.; Cavazos-Guerra, Carolina; Artaxo, Paulo; Colarco, Peter; Washington, Richard

2018-01-01

Millions of tons of mineral dust are lifted by the wind from arid surfaces and transported around the globe every year. The physical and chemical properties of the mineral dust are needed to better constrain remote sensing observations and are of fundamental importance for the understanding of dust atmospheric processes. Ground-based in situ measurements and in situ filter collection of Saharan dust were obtained during the Fennec campaign in the central Sahara in 2011. This paper presents results of the absorption and scattering coefficients, and hence single scattering albedo (SSA), of the Saharan dust measured in real time during the last period of the campaign and subsequent laboratory analysis of the dust samples collected in two supersites, SS1 and SS2, in Algeria and in Mauritania, respectively. The samples were taken to the laboratory, where their size and aspect ratio distributions, mean chemical composition, spectral mass absorption efficiency, and spectral imaginary refractive index were obtained from the ultraviolet (UV) to the near-infrared (NIR) wavelengths. At SS1 in Algeria, the time series of the scattering coefficients during the period of the campaign show dust events exceeding 3500 Mm-1, and a relatively high mean SSA of 0.995 at 670 nm was observed at this site. The laboratory results show for the fine particle size distributions (particles diameter  < 5µm and mode diameter at 2-3 µm) in both sites a spectral dependence of the imaginary part of the refractive index Im(m) with a bow-like shape, with increased absorption in UV as well as in the shortwave infrared. The same signature was not observed, however, in the mixed particle size distribution (particle diameter < 10 µm and mode diameter at 4 µm) in Algeria. Im(m) was found to range from 0.011 to 0.001i for dust collected in Algeria and 0.008 to 0.002i for dust collected in Mauritania over the wavelength range of 350-2500 nm. Differences in the mean elemental

Laboratory Study of Aliphatic Organic Spectral Signatures and Applications to Ceres and Primitive Asteroids

NASA Astrophysics Data System (ADS)

Kaplan, H. H.; Milliken, R.

2017-12-01

Aliphatic organics were recently discovered on the surface of Ceres with Dawn's Visible and InfraRed (VIR) mapping spectrometer, which has implications for prebiotic chemistry of Ceres and other asteroids. An absorption in the spectrum at 3.4 µm was used to identify and provide initial estimates of the amount of organic material. We have studied the 3.4 µm absorption in reflectance spectra of bulk rock and meteorite powders and isolated organic materials in the NASA RELAB facility at Brown University to determine how organic composition and abundance affects absorption strength. Reflectance spectra of insoluble organic matter (IOM) extracted from carbonaceous chondrites were measured from 0.35 - 25 µm. These IOM have known elemental (H, C, N, O) and isotopic compositions that were compared with spectral properties. Bulk meteorites were measured as chips and particulates over the same wavelength range. Despite overall low reflectance values (albedo <0.01), the 3.4 µm absorption is observed for some IOM samples, specifically those with a H/C ratio greater than 0.4. The absorption strength (band depth) increases with increasing H/C ratio, which corroborates similar findings in our previous study of sedimentary rocks and isolated kerogens. The absorption strength in the bulk meteorites reflects both H/C of the IOM and the concentration of IOM in the inorganic (mineral) matrix. Overlapping absorptions from carbonates and phyllosilicates (OH/H2O) can also influence the aliphatic organic bands in bulk rocks and meteorites. This laboratory work provides a foundation that can be used to constrain the composition of Ceres' aliphatic organic matter using band depth as a proxy for H/C. Reflectance spectra collected for this work will also be used to model the Dawn VIR data and obtain abundance and H/C estimates assuming that the organic material on Ceres' surface is similar to carbonaceous chondrite IOM. These spectra and findings can aid interpretation of reflectance data

Switched integration amplifier-based photocurrent meter for accurate spectral responsivity measurement of photometers.

PubMed

Park, Seongchong; Hong, Kee-Suk; Kim, Wan-Seop

2016-03-20

This work introduces a switched integration amplifier (SIA)-based photocurrent meter for femtoampere (fA)-level current measurement, which enables us to measure a 10⁷ dynamic range of spectral responsivity of photometers even with a common lamp-based monochromatic light source. We described design considerations and practices about operational amplifiers (op-amps), switches, readout methods, etc., to compose a stable SIA of low offset current in terms of leakage current and gain peaking in detail. According to the design, we made six SIAs of different integration capacitance and different op-amps and evaluated their offset currents. They showed an offset current of (1.5-85) fA with a slow variation of (0.5-10) fA for an hour under opened input. Applying a detector to the SIA input, the offset current and its variation were increased and the SIA readout became noisier due to finite shunt resistance and nonzero shunt capacitance of the detector. One of the SIAs with 10 pF nominal capacitance was calibrated using a calibrated current source at the current level of 10 nA to 1 fA and at the integration time of 2 to 65,536 ms. As a result, we obtained a calibration formula for integration capacitance as a function of integration time rather than a single capacitance value because the SIA readout showed a distinct dependence on integration time at a given current level. Finally, we applied it to spectral responsivity measurement of a photometer. It is demonstrated that the home-made SIA of 10 pF was capable of measuring a 10⁷ dynamic range of spectral responsivity of a photometer.

Laboratory demonstration of a Brillouin lidar to remotely measure temperature profiles of the ocean

NASA Astrophysics Data System (ADS)

Rudolf, Andreas; Walther, Thomas

2014-05-01

We report on the successful laboratory demonstration of a real-time lidar system to remotely measure temperature profiles in water. In the near future, it is intended to be operated from a mobile platform, e.g., a helicopter or vessel, in order to precisely determine the temperature of the surface mixed layer of the ocean with high spatial resolution. The working principle relies on the active generation and detection of spontaneous Brillouin scattering. The light source consists of a frequency-doubled fiber-amplified external cavity diode laser and provides high-energy, Fourier transform-limited laser pulses in the green spectral range. The detector is based on an atomic edge filter and allows the challenging extraction of the temperature information from the Brillouin scattered light. In the lab environment, depending on the amount of averaging, water temperatures were resolved with a mean accuracy of up to 0.07°C and a spatial resolution of 1 m, proving the feasibility and the large potential of the overall system.

Imaging Cellular Dynamics with Spectral Relaxation Imaging Microscopy: Distinct Spectral Dynamics in Golgi Membranes of Living Cells.

PubMed

Lajevardipour, Alireza; Chon, James W M; Chattopadhyay, Amitabha; Clayton, Andrew H A

2016-11-22

Spectral relaxation from fluorescent probes is a useful technique for determining the dynamics of condensed phases. To this end, we have developed a method based on wide-field spectral fluorescence lifetime imaging microscopy to extract spectral relaxation correlation times of fluorescent probes in living cells. We show that measurement of the phase and modulation of fluorescence from two wavelengths permit the identification and determination of excited state lifetimes and spectral relaxation correlation times at a single modulation frequency. For NBD fluorescence in glycerol/water mixtures, the spectral relaxation correlation time determined by our approach exhibited good agreement with published dielectric relaxation measurements. We applied this method to determine the spectral relaxation dynamics in membranes of living cells. Measurements of the Golgi-specific C 6 -NBD-ceramide probe in living HeLa cells revealed sub-nanosecond spectral dynamics in the intracellular Golgi membrane and slower nanosecond spectral dynamics in the extracellular plasma membrane. We interpret the distinct spectral dynamics as a result of structural plasticity of the Golgi membrane relative to more rigid plasma membranes. To the best of our knowledge, these results constitute one of the first measurements of Golgi rotational dynamics.

WINDOWS: a program for the analysis of spectral data foil activation measurements

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

Stallmann, F.W.; Eastham, J.F.; Kam, F.B.K.

The computer program WINDOWS together with its subroutines is described for the analysis of neutron spectral data foil activation measurements. In particular, the unfolding of the neutron differential spectrum, estimated windows and detector contributions, upper and lower bounds for an integral response, and group fluxes obtained from neutron transport calculations. 116 references. (JFP)

Use of high-dimensional spectral data to evaluate organic matter, reflectance relationships in soils

NASA Technical Reports Server (NTRS)

Henderson, T. L.; Baumgardner, M. F.; Coster, D. C.; Franzmeier, D. P.; Stott, D. E.

1990-01-01

Recent breakthroughs in remote sensing technology have led to the development of a spaceborne high spectral resolution imaging sensor, HIRIS, to be launched in the mid-1990s for observation of earth surface features. The effects of organic carbon content on soil reflectance over the spectral range of HIRIS, and to examine the contributions of humic and fulvic acid fractions to soil reflectance was evaluated. Organic matter from four Indiana agricultural soils was extracted, fractionated, and purified, and six individual components of each soil were isolated and prepared for spectral analysis. The four soils, ranging in organic carbon content from 0.99 percent, represented various combinations of genetic parameters such as parent material, age, drainage, and native vegetation. An experimental procedure was developed to measure reflectance of very small soil and organic component samples in the laboratory, simulating the spectral coverage and resolution of the HIRIS sensor. Reflectance in 210 narrow (10 nm) bands was measured using the CARY 17D spectrophotometer over the 400 to 2500 nm wavelength range. Reflectance data were analyzed statistically to determine the regions of the reflective spectrum which provided useful information about soil organic matter content and composition. Wavebands providing significant information about soil organic carbon content were located in all three major regions of the reflective spectrum: visible, near infrared, and middle infrared. The purified humic acid fractions of the four soils were separable in six bands in the 1600 to 2400 nm range, suggesting that longwave middle infrared reflectance may be useful as a non-destructive laboratory technique for humic acid characterization.

Measurement of refractive index of hemoglobin in the visible/NIR spectral range

NASA Astrophysics Data System (ADS)

Lazareva, Ekaterina N.; Tuchin, Valery V.

2018-03-01

This study is focused on the measurements of the refractive index of hemoglobin solutions in the visible/near-infrared (NIR) spectral range at room temperature for characteristic laser wavelengths: 480, 486, 546, 589, 644, 656, 680, 930, 1100, 1300, and 1550 nm. Measurements were performed using the multiwavelength Abbe refractometer. Aqua hemoglobin solutions of different concentrations obtained from human whole blood were investigated. The specific increment of refractive index on hemoglobin concentration and the Sellmeier coefficients were calculated.

NOAA's Van-Based Mobile Atmospheric Emissions Measurement Laboratory

NASA Astrophysics Data System (ADS)

Dube, W. P.; Peischl, J.; Neuman, J. A.; Eilerman, S. J.; Holloway, M.; Roberts, O.; Aikin, K. C.; Ryerson, T. B.

2015-12-01

The Chemical Science Division (CSD) mobile atmospheric emissions measurement laboratory is the second and latest of two mobile measurement vans outfitted for atmospheric sampling by the NOAA Earth System Research Laboratory. In this presentation we will describe the modifications made to this vehicle to provide a versatile and relatively inexpensive instrument platform including: the 2 kW 120 volt instrument power system; battery back-up system; data acquisition system; real-time display; meteorological, directional, and position sensor package; and the typical atmospheric emissions instrument package. The van conversion uses commercially available, off-the-shelf components from the marine and RV industries, thus keeping the costs quite modest.

New Improvements in Magnetic Measurements Laboratory of the ALBA Synchrotron Facility

NASA Astrophysics Data System (ADS)

Campmany, Josep; Marcos, Jordi; Massana, Valentí

ALBA synchrotron facility has a complete insertion devices (ID) laboratory to characterize and produce magnetic devices needed to satisfy the requirements of ALBA's user community. The laboratory is equipped with a Hall-probe bench working in on-the-fly measurement mode allowing the measurement of field maps of big magnetic structures with high accuracy, both in magnetic field magnitude and position. The whole control system of this bench is based on TANGO. The Hall probe calibration range extends between sub-Gauss to 2 Tesla with an accuracy of 100 ppm. Apart from the Hall probe bench, the ID laboratory has a flipping coil bench dedicated to measuring field integrals and a Helmholtz coil bench specially designed to characterize permanent magnet blocks. Also, a fixed stretched wire bench is used to measure field integrals of magnet sets. This device is specifically dedicated to ID construction. Finally, the laboratory is equipped with a rotating coil bench, specially designed for measuring multipolar devices used in accelerators, such as quadrupoles, sextupoles, etc. Recent improvements of the magnetic measurements laboratory of ALBA synchrotron include the design and manufacturing of very thin 3D Hall probe heads, the design and manufacturing of coil sensors for the Rotating coil bench based on multilayered PCB, and the improvement of calibration methodology in order to improve the accuracy of the measurements. ALBA magnetic measurements laboratory is open for external contracts, and has been widely used by national and international institutes such as CERN, ESRF or CIEMAT, as well as magnet manufacturing companies, such as ANTEC, TESLA and I3 M. In this paper, we will present the main features of the measurement benches as well as improvements made so far.

Classification of Hyperspectral or Trichromatic Measurements of Ocean Color Data into Spectral Classes.

PubMed

Prasad, Dilip K; Agarwal, Krishna

2016-03-22

We propose a method for classifying radiometric oceanic color data measured by hyperspectral satellite sensors into known spectral classes, irrespective of the downwelling irradiance of the particular day, i.e., the illumination conditions. The focus is not on retrieving the inherent optical properties but to classify the pixels according to the known spectral classes of the reflectances from the ocean. The method compensates for the unknown downwelling irradiance by white balancing the radiometric data at the ocean pixels using the radiometric data of bright pixels (typically from clouds). The white-balanced data is compared with the entries in a pre-calibrated lookup table in which each entry represents the spectral properties of one class. The proposed approach is tested on two datasets of in situ measurements and 26 different daylight illumination spectra for medium resolution imaging spectrometer (MERIS), moderate-resolution imaging spectroradiometer (MODIS), sea-viewing wide field-of-view sensor (SeaWiFS), coastal zone color scanner (CZCS), ocean and land colour instrument (OLCI), and visible infrared imaging radiometer suite (VIIRS) sensors. Results are also shown for CIMEL's SeaPRISM sun photometer sensor used on-board field trips. Accuracy of more than 92% is observed on the validation dataset and more than 86% is observed on the other dataset for all satellite sensors. The potential of applying the algorithms to non-satellite and non-multi-spectral sensors mountable on airborne systems is demonstrated by showing classification results for two consumer cameras. Classification on actual MERIS data is also shown. Additional results comparing the spectra of remote sensing reflectance with level 2 MERIS data and chlorophyll concentration estimates of the data are included.

Comparing Laboratory and Field Measured Bioaccumulation Endpoints

EPA Science Inventory

The report presents an approach that allows comparisons of all laboratory and field bioaccumulation endpoints measurements. The approach will enable the inclusion of large amounts of field data into evaluations of bioaccumulation potential for legacy chemicals. Currently, these...

A NOVEL TECHNIQUE APPLYING SPECTRAL ESTIMATION TO JOHNSON NOISE THERMOMETRY

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

Ezell, N Dianne Bull; Britton Jr, Charles L; Roberts, Michael

Johnson noise thermometry (JNT) is one of many important measurements used to monitor the safety levels and stability in a nuclear reactor. However, this measurement is very dependent on the electromagnetic environment. Properly removing unwanted electromagnetic interference (EMI) is critical for accurate drift free temperature measurements. The two techniques developed by Oak Ridge National Laboratory (ORNL) to remove transient and periodic EMI are briefly discussed in this document. Spectral estimation is a key component in the signal processing algorithm utilized for EMI removal and temperature calculation. Applying these techniques requires the simple addition of the electronics and signal processing tomore » existing resistive thermometers.« less

Radiometric spectral and band rendering of targets using anisotropic BRDFs and measured backgrounds

NASA Astrophysics Data System (ADS)

Hilgers, John W.; Hoffman, Jeffrey A.; Reynolds, William R.; Jafolla, James C.

2000-07-01

Achievement of ultra-high fidelity signature modeling of targets requires a significant level of complexity for all of the components required in the rendering process. Specifically, the reflectance of the surface must be described using the bi-directional distribution function (BRDF). In addition, the spatial representation of the background must be high fidelity. A methodology and corresponding model for spectral and band rendering of targets using both isotropic and anisotropic BRDFs is presented. In addition, a set of tools will be described for generating theoretical anisotropic BRDFs and for reducing data required for a description of an anisotropic BRDF by 5 orders of magnitude. This methodology is hybrid using a spectrally measured panoramic of the background mapped to a large hemisphere. Both radiosity and ray-tracing approaches are incorporated simultaneously for a robust solution. In the thermal domain the spectral emission is also included in the solution. Rendering examples using several BRDFs will be presented.

Laboratory measurements of gravel thermal properties. A methodology proposal

NASA Astrophysics Data System (ADS)

Cultrera, Matteo; Peron, Fabio; Bison, Paolo; Dalla Santa, Giorgia; Bertermann, David; Muller, Johannes; Bernardi, Adriana; Galgaro, Antonio

2017-04-01

Gravel thermal properties measurements at laboratory level is quite challenging due to several technical and logistic issues, mainly connected to the sediment sizes and the variability of their mineralogical composition. The direct measurement of gravel thermal properties usually are not able to involve a representative volume of geological material, consequently the thermal measurements performed produce much dispersed results and not consistent due to the large interstitial voids and the poor physical contact with the measuring sensors. With the aim of directly provide the measurement of the gravel thermal properties, a new methodology has been developed and some results are already available on several gravel deposits samples around Europe. Indeed, a single guarded hot plate Taurus Instruments TLP 800 measured the gravel thermal properties. Some instrumental adjustments were necessary to adapt the measuring devices and to finalize the thermal measurements on gravels at the IUAV FISTEC laboratory (Environmental Technical Physics Laboratory of Venice University). This device usually provides thermal measurements according to ISO 8302, ASTM C177, EN 1946-2, EN 12664, EN 12667 and EN 12939 for building materials. A preliminary calibration has been performed comparing the outcomes obtained with the single guarded hot plate with a needle probe of a portable thermal conductivity meter (ISOMET). Standard sand (ISO 67:2009) is used as reference material. This study is provided under the Cheap-GSHPs project that has received funding from the European Union's Horizon 2020 research and innovation program under grant agreement no. 657982

Interstellar PAH in the Laboratory and in Space. What have we Learned from the New Generation of Laboratory and Observational Studies?

NASA Technical Reports Server (NTRS)

Salama, Farid

2005-01-01

Polycyclic Aromatic Hydrocarbons (PAHs) are an important and ubiquitous component of carbon-bearing materials in space. PAHs are the best-known candidates to account for the IR emission bands (UIR bands) and PAH spectral features are now being used as new probes of the ISM. PAHs are also thought to be among the carriers of the diffuse interstellar absorption bands (DIBs). In the model dealing with the interstellar spectral features, PAHs are present as a mixture of radicals, ions and neutral species. PAH ionization states reflect the ionization balance of the medium while PAH size, composition, and structure reflect the energetic and chemical history of the medium. A major challenge for laboratory astrophysics is to reproduce (in a realistic way) the physical conditions that exist in the emission and/or absorption interstellar zones. An extensive laboratory program has been developed at NASA Ames to assess the physical and chemical properties of PAHs in such environments and to describe how they influence the radiation and energy balance in space and the interstellar chemistry. In particular, laboratory experiments provide measurements of the spectral characteristics of interstellar PAH analogs from the ultraviolet and visible range to the infrared range for comparison with astronomical data. This paper will focus on the recent progress made in the laboratory to measure the direct absorption spectra of neutral and ionized PAHs in the gas phase in the near-UV and visible range in astrophysically relevant environments. These measurements provide data on PAHs and nanometer-sized particles that can now be directly compared to astronomical observations. The harsh physical conditions of the IS medium - characterized by a low temperature, an absence of collisions and strong VUV radiation fields - are simulated in the laboratory by associating a molecular beam with an ionizing discharge to generate a cold plasma expansion. PAH ions are formed from the neutral precursors in

Measurement of spectral phase noise in a cryogenically cooled Ti:Sa amplifier (Conference Presentation)

NASA Astrophysics Data System (ADS)

Nagymihaly, Roland S.; Jójárt, Péter; Börzsönyi, Ádám.; Osvay, Károly

2017-05-01

In most of cases the drift of the carrier envelope phase (CEP) of a chirped pulse amplifier (CPA) system is determined only [1], being the relevant parameter at laser-matter interactions. The need of coherent combination of multiple amplifier channels to further increase the peak power of pulses requires interferometric precision [2]. For this purpose, the stability of the group delay of the pulses may become equally important. Further development of amplifier systems requires the investigation of phase noise contributions of individual subsystems, like amplifier stages. Spectrally resolved interferometry (SRI), which is a completely linear optical method, makes the measurement of spectral phase noise possible of basically any part of a laser system [3]. By utilizing this method, the CEP stability of water-cooled Ti:Sa based amplifiers was investigated just recently, where the effects of seed and pump energy, repetition rate, and the cooling crystal mounts were thoroughly measured [4]. We present a systematic investigation on the noise of the spectral phase, including CEP, of laser pulses amplified in a cryogenically-cooled Ti:Sa amplifier of a CPA chain. The double-pass amplifier was built in the sample arm of a compact Michelson interferometer. The Ti:Sa crystal was cooled below 30 °K. The inherent phase noise was measured for different operation modes, as at various repetition rates, and pump depletion. Noise contributions of the vacuum pumps and the cryogenic refrigerator were found to be 43 and 47 mrad, respectively. We have also identified CEP noise having thermal as well as mechanical origin. Both showed a monotonically decreasing tendency towards higher repetition rates. We found that the widths of the noise distributions are getting broader towards lower repetition rates. Spectral phase noise with and without amplification was measured, and we found no significant difference in the phase noise distributions. The mechanical vibration was also measured in

Proficiency Tests for Environmental Radioactivity Measurement Organized by an Accredited Laboratory

NASA Astrophysics Data System (ADS)

Aubert, Cédric; Osmond, Mélanie

2008-08-01

For 40 years, STEME (Environmental Sample Processing and Metrology Department) organized international proficiency testing (PT) exercises formerly for WHO (World Health Organization) and EC (European Community) and currently for ASN (French Nuclear Safety Authority). Five PT exercises are organized each year for the measurement of radionuclides (alpha, beta and gamma) in different matrixes (water, soil, biological and air samples) at environmental levels. ASN can deliver a French ministerial agreement to participate on environmental radioactivity measurements French network for laboratories asking it [1]. Since 2006, November, STEME is the first French entity obtaining a COFRAC (French Committee of Accreditation) accreditation as "Interlaboratory Comparisons" for the organization of proficiency tests for environmental radioactivity measurement according to standard International Standard Organization (ISO) 17025 and guide ISO 43-1. STEME has in charge to find, as far as possible, real sample or to create, by radionuclide adding, an adapted sample. STEME realizes the sampling, the samples preparation and the dispatching. STEME is also accredited according to Standard 17025 for radioactivity measurements in environmental samples and determines homogeneity, stability and reference values. After the reception of participating laboratories results, STEME executes statistical treatments in order to verify the normal distribution, to eliminate outliers and to evaluate laboratories performance. Laboratories participate with several objectives, to obtain French agreement, to prove the quality of their analytical performance in regards to standard 17025 or to validate new methods or latest developments. For 2 years, in addition to usual PT exercises, new PT about alpha or beta measurement in air filters, radioactive iodine in carbon cartridges or measurement of environmental dosimeters are organized. These PT exercises help laboratories to improve radioactive measurements

Proficiency Tests for Environmental Radioactivity Measurement Organized by an Accredited Laboratory

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

Aubert, Cedric; Osmond, Melanie

2008-08-14

For 40 years, STEME (Environmental Sample Processing and Metrology Department) organized international proficiency testing (PT) exercises formerly for WHO (World Health Organization) and EC (European Community) and currently for ASN (French Nuclear Safety Authority). Five PT exercises are organized each year for the measurement of radionuclides (alpha, beta and gamma) in different matrixes (water, soil, biological and air samples) at environmental levels. ASN can deliver a French ministerial agreement to participate on environmental radioactivity measurements French network for laboratories asking it. Since 2006, November, STEME is the first French entity obtaining a COFRAC (French Committee of Accreditation) accreditation as 'Interlaboratorymore » Comparisons' for the organization of proficiency tests for environmental radioactivity measurement according to standard International Standard Organization (ISO) 17025 and guide ISO 43-1. STEME has in charge to find, as far as possible, real sample or to create, by radionuclide adding, an adapted sample. STEME realizes the sampling, the samples preparation and the dispatching. STEME is also accredited according to Standard 17025 for radioactivity measurements in environmental samples and determines homogeneity, stability and reference values. After the reception of participating laboratories results, STEME executes statistical treatments in order to verify the normal distribution, to eliminate outliers and to evaluate laboratories performance.Laboratories participate with several objectives, to obtain French agreement, to prove the quality of their analytical performance in regards to standard 17025 or to validate new methods or latest developments. For 2 years, in addition to usual PT exercises, new PT about alpha or beta measurement in air filters, radioactive iodine in carbon cartridges or measurement of environmental dosimeters are organized. These PT exercises help laboratories to improve radioactive measurements

Microwave moisture measurement of cotton fiber moisture content in the laboratory

USDA-ARS?s Scientific Manuscript database

The moisture content of cotton fiber is an important fiber property, but it is often measured by a laborious, time-consuming laboratory oven drying method. A program was implemented to establish the capabilities of a laboratory microwave moisture measurement instrument to perform rapid, precise and...

Solar Spectral Irradiance Variability in Cycle 24: Model Predictions and OMI Observations

NASA Technical Reports Server (NTRS)

Marchenko, S.; DeLand, M.; Lean, J.

2016-01-01

Utilizing the excellent stability of the Ozone Monitoring Instrument (OMI), we characterize both short-term (solar rotation) and long-term (solar cycle) changes of the solar spectral irradiance (SSI) between 265-500 nanometers during the ongoing Cycle 24. We supplement the OMI data with concurrent observations from the GOME-2 (Global Ozone Monitoring Experiment - 2) and SORCE (Solar Radiation and Climate Experiment) instruments and find fair-to-excellent agreement between the observations and predictions of the NRLSSI2 (Naval Research Laboratory Solar Spectral Irradiance - post SORCE) and SATIRE-S (the Naval Research Laboratory's Spectral And Total Irradiance REconstruction for the Satellite era) models.

Spectral control of an alexandrite laser for an airborne water-vapor differential absorption lidar system

NASA Technical Reports Server (NTRS)

Ponsardin, Patrick; Grossmann, Benoist E.; Browell, Edward V.

1994-01-01

A narrow-linewidth pulsed alexandrite laser has been greatly modified for improved spectral stability in an aircraft environment, and its operation has been evaluated in the laboratory for making water-vapor differential absorption lidar measurements. An alignment technique is described to achieve the optimum free spectral range ratio for the two etalons inserted in the alexandrite laser cavity, and the sensitivity of this ratio is analyzed. This technique drastically decreases the occurrence of mode hopping, which is commonly observed in a tunable, two-intracavity-etalon laser system. High spectral purity (greater than 99.85%) at 730 nm is demonstrated by the use of a water-vapor absorption line as a notch filter. The effective cross sections of 760-nm oxygen and 730-nm water-vapor absorption lines are measured at different pressures by using this laser, which has a finite linewidth of 0.02 cm(exp -1) (FWHM). It is found that for water-vapor absorption linewidths greater than 0.04 cm(exp -1) (HWHM), or for altitudes below 10 km, the laser line can be considered monochromatic because the measured effective absorption cross section is within 1% of the calculated monochromatic cross section. An analysis of the environmental sensitivity of the two intracavity etalons is presented, and a closed-loop computer control for active stabilization of the two intracavity etalons in the alexandrite laser is described. Using a water-vapor absorption line as a wavelength reference, we measure a long-term frequency drift (approximately 1.5 h) of less than 0.7 pm in the laboratory.

Measurement of centering error for probe of swing arm profilometer using a spectral confocal sensor

NASA Astrophysics Data System (ADS)

Chen, Lin; Jing, Hongwei; Wei, Zhongwei; Cao, Xuedong

2015-02-01

A spectral confocal sensor was used to measure the centering error for probe of swing arm profilometer (SAP). The feasibility of this technology was proved through simulation and experiment. The final measurement results was also analyzed to evaluate the advantages and disadvantages of this technology.

Tropospheric Ozone Near-Nadir-Viewing IR Spectral Sensitivity and Ozone Measurements from NAST-I

NASA Technical Reports Server (NTRS)

Zhou, Daniel K.; Smith, William L.; Larar, Allen M.

2001-01-01

Infrared ozone spectra from near nadir observations have provided atmospheric ozone information from the sensor to the Earth's surface. Simulations of the NPOESS Airborne Sounder Testbed-Interferometer (NAST-I) from the NASA ER-2 aircraft (approximately 20 km altitude) with a spectral resolution of 0.25/cm were used for sensitivity analysis. The spectral sensitivity of ozone retrievals to uncertainties in atmospheric temperature and water vapor is assessed in order to understand the relationship between the IR emissions and the atmospheric state. In addition, ozone spectral radiance sensitivity to its ozone layer densities and radiance weighting functions reveals the limit of the ozone profile retrieval accuracy from NAST-I measurements. Statistical retrievals of ozone with temperature and moisture retrievals from NAST-I spectra have been investigated and the preliminary results from NAST-I field campaigns are presented.

The influence of the spectral emissivity of flat-plate calibrators on the calibration of IR thermometers

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

Cárdenas-García, D.; Méndez-Lango, E.

Flat Calibrators (FC) are an option for calibration of infrared thermometers (IT) with a fixed large target. FCs are neither blackbodies, nor gray-bodies; their spectral emissivity is lower than one and depends on wavelength. Nevertheless they are used as gray-bodies with a nominal emissivity value. FCs can be calibrated radiometrically using as reference a calibrated IR thermometer (RT). If an FC will be used to calibrate ITs that work in the same spectral range as the RT then its calibration is straightforward: the actual FC spectral emissivity is not required. This result is valid for any given fixed emissivity assessedmore » to the FC. On the other hand, when the RT working spectral range does not match with that of the ITs to be calibrated with the FC then it is required to know the FC spectral emissivity as part of the calibration process. For this purpose, at CENAM, we developed an experimental setup to measure spectral emissivity in the infrared spectral range, based on a Fourier transform infrared spectrometer. Not all laboratories have emissivity measurement capability in the appropriate wavelength and temperature ranges to obtain the spectral emissivity. Thus, we present an estimation of the error introduced when the spectral range of the RT used to calibrate an FC and the spectral ranges of the ITs to be calibrated with the FC do not match. Some examples are developed for the cases when RT and IT spectral ranges are [8,13] μm and [8,14] μm respectively.« less

Radon Mitigation Approach in a Laboratory Measurement Room

PubMed Central

Blanco-Rodríguez, Patricia; Fernández-Serantes, Luis Alfonso; Otero-Pazos, Alberto; Calvo-Rolle, José Luis; de Cos Juez, Francisco Javier

2017-01-01

Radon gas is the second leading cause of lung cancer, causing thousands of deaths annually. It can be a problem for people or animals in houses, workplaces, schools or any building. Therefore, its mitigation has become essential to avoid health problems and to prevent radon from interfering in radioactive measurements. This study describes the implementation of radon mitigation systems at a radioactivity laboratory in order to reduce interferences in the different works carried out. A large set of radon concentration samples is obtained from measurements at the laboratory. While several mitigation methods were taken into account, the final applied solution is explained in detail, obtaining thus very good results by reducing the radon concentration by 76%. PMID:28492468

Radon Mitigation Approach in a Laboratory Measurement Room.

PubMed

Blanco-Rodríguez, Patricia; Fernández-Serantes, Luis Alfonso; Otero-Pazos, Alberto; Calvo-Rolle, José Luis; de Cos Juez, Francisco Javier

2017-05-11

Radon gas is the second leading cause of lung cancer, causing thousands of deaths annually. It can be a problem for people or animals in houses, workplaces, schools or any building. Therefore, its mitigation has become essential to avoid health problems and to prevent radon from interfering in radioactive measurements. This study describes the implementation of radon mitigation systems at a radioactivity laboratory in order to reduce interferences in the different works carried out. A large set of radon concentration samples is obtained from measurements at the laboratory. While several mitigation methods were taken into account, the final applied solution is explained in detail, obtaining thus very good results by reducing the radon concentration by 76%.

Quantitative lithologic mapping in spectral ratio feature space - Volcanic, sedimentary and metamorphic terrains

NASA Technical Reports Server (NTRS)

Campos-Marquetti, Raul, Jr.; Rockwell, Barnaby

1990-01-01

The nature of spectral lithologic mapping is studied utilizing ratios centered around the wavelength means of TM imagery. Laboratory-derived spectra are analyzed to determine the two-dimensional relationships and distributions visible in spectral ratio feature space. The spectral distributions of various rocks and minerals in ratio feature space are found to be controlled by several spectrally dominant molecules. Three study areas were examined: Rawhide Mining District, Nevada; Manzano Mountains, New Mexico; and the Sevilleta Long Term Ecological Research site in New Mexico. It is shown that, in the comparison of two ratio plots of laboratory reflectance spectra, i.e., 0.66/0.485 micron versus 1.65/2.22 microns with those derived from TM data, several molecules spectrally dominate the reflectance characteristic of surface lithologic units. Utilizing the above ratio combination, two areas are successfully mapped based on their distribution in spectral ratio feature space.

A method for developing outcome measures in the clinical laboratory.

PubMed

Jones, J

1996-01-01

Measuring and reporting outcomes in health care is becoming more important for quality assessment, utilization assessment, accreditation standards, and negotiating contracts in managed care. How does one develop an outcome measure for the laboratory to assess the value of the services? A method is described which outlines seven steps in developing outcome measures for a laboratory service or process. These steps include the following: 1. Identify the process or service to be monitored for performance and outcome assessment. 2. If necessary, form an multidisciplinary team of laboratory staff, other department staff, physicians, and pathologists. 3. State the purpose of the test or service including a review of published data for the clinical pathological correlation. 4. Prepare a process cause and effect diagram including steps critical to the outcome. 5. Identify key process variables that contribute to positive or negative outcomes. 6. Identify outcome measures that are not process measures. 7. Develop an operational definition, identify data sources, and collect data. Examples, including a process cause and effect diagram, process variables, and outcome measures, are given using the Therapeutic Drug Monitoring service (TDM). A summary of conclusions and precautions for outcome measurement is then provided.

Spectral measurements of alpha-induced radioluminescence in various gases

NASA Astrophysics Data System (ADS)

Brett, Jaclyn; Koehler, Katrina E.; Bischak, Michael; Famiano, Michael; Jenkins, Jared; Klankowski, Levi; Niraula, Prashantamani; Pancella, Paul; Lakis, Rollin

2017-12-01

Radioluminescent emission in Ar, N2, O2, and dry air at P = 1 atm was observed induced by 5 MeV α particles. The wavelength range with a single detector spanned 250-1100 nm, extending the range well into the UV and IR bands with a single detector. Measured spectral lines for alpha-induced luminescence were corrected for detector transmission and intensities compared to previous work. The exploration of multiple gases over a wide frequency range opens the door to security and remote sensing applications, where different environments are routinely encountered. This work provides spectra that can be used in guiding future filter development focusing on remote alpha detection.

Retrieving vertical ozone profiles from measurements of global spectral irradiance

NASA Astrophysics Data System (ADS)

Bernhard, Germar; Petropavlovskikh, Irina; Mayer, Bernhard

2017-12-01

A new method is presented to determine vertical ozone profiles from measurements of spectral global (direct Sun plus upper hemisphere) irradiance in the ultraviolet. The method is similar to the widely used Umkehr technique, which inverts measurements of zenith sky radiance. The procedure was applied to measurements of a high-resolution spectroradiometer installed near the centre of the Greenland ice sheet. Retrieved profiles were validated with balloon-sonde observations and ozone profiles from the space-borne Microwave Limb Sounder (MLS). Depending on altitude, the bias between retrieval results presented in this paper and MLS observations ranges between -5 and +3 %. The magnitude of this bias is comparable, if not smaller, to values reported in the literature for the standard Dobson Umkehr method. Total ozone columns (TOCs) calculated from the retrieved profiles agree to within 0.7±2.0 % (±1σ) with TOCs measured by the Ozone Monitoring Instrument on board the Aura satellite. The new method is called the Global-Umkehr method.

Hyperspectral Remote Sensing and Ecological Modeling Research and Education at Mid America Remote Sensing Center (MARC): Field and Laboratory Enhancement

NASA Technical Reports Server (NTRS)

Cetin, Haluk

1999-01-01

The purpose of this project was to establish a new hyperspectral remote sensing laboratory at the Mid-America Remote sensing Center (MARC), dedicated to in situ and laboratory measurements of environmental samples and to the manipulation, analysis, and storage of remotely sensed data for environmental monitoring and research in ecological modeling using hyperspectral remote sensing at MARC, one of three research facilities of the Center of Reservoir Research at Murray State University (MSU), a Kentucky Commonwealth Center of Excellence. The equipment purchased, a FieldSpec FR portable spectroradiometer and peripherals, and ENVI hyperspectral data processing software, allowed MARC to provide hands-on experience, education, and training for the students of the Department of Geosciences in quantitative remote sensing using hyperspectral data, Geographic Information System (GIS), digital image processing (DIP), computer, geological and geophysical mapping; to provide field support to the researchers and students collecting in situ and laboratory measurements of environmental data; to create a spectral library of the cover types and to establish a World Wide Web server to provide the spectral library to other academic, state and Federal institutions. Much of the research will soon be published in scientific journals. A World Wide Web page has been created at the web site of MARC. Results of this project are grouped in two categories, education and research accomplishments. The Principal Investigator (PI) modified remote sensing and DIP courses to introduce students to ii situ field spectra and laboratory remote sensing studies for environmental monitoring in the region by using the new equipment in the courses. The PI collected in situ measurements using the spectroradiometer for the ER-2 mission to Puerto Rico project for the Moderate Resolution Imaging Spectrometer (MODIS) Airborne Simulator (MAS). Currently MARC is mapping water quality in Kentucky Lake and

Spectral Invariance Principles Observed in Spectral Radiation Measurements of the Transition Zone

NASA Technical Reports Server (NTRS)

Marshak, Alexander

2011-01-01

The main theme for our research is the understanding and closure of the surface spectral shortwave radiation problem in fully 3D cloud situations by combining the new ARM scanning radars, shortwave spectrometers, and microwave radiometers with the arsenal of radiative transfer tools developed by our group. In particular, we define first a large number of cloudy test cases spanning all 3D possibilities not just the customary uniform-overcast ones. Second, for each case, we define a "Best Estimate of Clouds That Affect Shortwave Radiation" using all relevant ARM instruments, notably the new scanning radars, and contribute this to the ARM Archive. Third, we test the ASR-signature radiative transfer model RRTMG_SW for those cases, focusing on the near-IR because of long-standing problems in this spectral region, and work with the developers to improve RRTMG_SW in order to increase its penetration into the modeling community.

Using spectral methods to obtain particle size information from optical data: applications to measurements from CARES 2010

NASA Astrophysics Data System (ADS)

Atkinson, Dean B.; Pekour, Mikhail; Chand, Duli; Radney, James G.; Kolesar, Katheryn R.; Zhang, Qi; Setyan, Ari; O'Neill, Norman T.; Cappa, Christopher D.

2018-04-01

Multi-wavelength in situ aerosol extinction, absorption and scattering measurements made at two ground sites during the 2010 Carbonaceous Aerosols and Radiative Effects Study (CARES) are analyzed using a spectral deconvolution method that allows extraction of particle-size-related information, including the fraction of extinction produced by the fine-mode particles and the effective radius of the fine mode. The spectral deconvolution method is typically applied to analysis of remote sensing measurements. Here, its application to in situ measurements allows for comparison with more direct measurement methods and validation of the retrieval approach. Overall, the retrieved fine-mode fraction and effective radius compare well with other in situ measurements, including size distribution measurements and scattering and absorption measurements made separately for PM1 and PM10, although there were some periods during which the different methods yielded different results. One key contributor to differences between the results obtained is the alternative, spectrally based definitions of fine and coarse modes from the optical methods, relative to instruments that use a physically defined cut point. These results indicate that for campaigns where size, composition and multi-wavelength optical property measurements are made, comparison of the results can result in closure or can identify unusual circumstances. The comparison here also demonstrates that in situ multi-wavelength optical property measurements can be used to determine information about particle size distributions in situations where direct size distribution measurements are not available.

Using spectral methods to obtain particle size information from optical data: applications to measurements from CARES 2010

DOE PAGES

Atkinson, Dean B.; Pekour, Mikhail; Chand, Duli; ...

2018-04-23

Here, multi-wavelength in situ aerosol extinction, absorption and scattering measurements made at two ground sites during the 2010 Carbonaceous Aerosols and Radiative Effects Study (CARES) are analyzed using a spectral deconvolution method that allows extraction of particle-size-related information, including the fraction of extinction produced by the fine-mode particles and the effective radius of the fine mode. The spectral deconvolution method is typically applied to analysis of remote sensing measurements. Here, its application to in situ measurements allows for comparison with more direct measurement methods and validation of the retrieval approach. Overall, the retrieved fine-mode fraction and effective radius compare wellmore » with other in situ measurements, including size distribution measurements and scattering and absorption measurements made separately for PM 1 and PM 10, although there were some periods during which the different methods yielded different results. One key contributor to differences between the results obtained is the alternative, spectrally based definitions of fine and coarse modes from the optical methods, relative to instruments that use a physically defined cut point. These results indicate that for campaigns where size, composition and multi-wavelength optical property measurements are made, comparison of the results can result in closure or can identify unusual circumstances. The comparison here also demonstrates that in situ multi-wavelength optical property measurements can be used to determine information about particle size distributions in situations where direct size distribution measurements are not available.« less

Using spectral methods to obtain particle size information from optical data: applications to measurements from CARES 2010

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

Atkinson, Dean B.; Pekour, Mikhail; Chand, Duli

Here, multi-wavelength in situ aerosol extinction, absorption and scattering measurements made at two ground sites during the 2010 Carbonaceous Aerosols and Radiative Effects Study (CARES) are analyzed using a spectral deconvolution method that allows extraction of particle-size-related information, including the fraction of extinction produced by the fine-mode particles and the effective radius of the fine mode. The spectral deconvolution method is typically applied to analysis of remote sensing measurements. Here, its application to in situ measurements allows for comparison with more direct measurement methods and validation of the retrieval approach. Overall, the retrieved fine-mode fraction and effective radius compare wellmore » with other in situ measurements, including size distribution measurements and scattering and absorption measurements made separately for PM 1 and PM 10, although there were some periods during which the different methods yielded different results. One key contributor to differences between the results obtained is the alternative, spectrally based definitions of fine and coarse modes from the optical methods, relative to instruments that use a physically defined cut point. These results indicate that for campaigns where size, composition and multi-wavelength optical property measurements are made, comparison of the results can result in closure or can identify unusual circumstances. The comparison here also demonstrates that in situ multi-wavelength optical property measurements can be used to determine information about particle size distributions in situations where direct size distribution measurements are not available.« less

Using spectral methods to obtain particle size information from optical data: applications to measurements from CARES 2010

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

Atkinson, Dean B.; Pekour, Mikhail; Chand, Duli

Multi-wavelength in situ aerosol extinction, absorption and scattering measurements made at two ground sites during the 2010 Carbonaceous Aerosols and Radiative Effects Study (CARES) are analyzed using a spectral deconvolution method that allows extraction of particle-size-related information, including the fraction of extinction produced by the fine-mode particles and the effective radius of the fine mode. The spectral deconvolution method is typically applied to analysis of remote sensing measurements. Here, its application to in situ measurements allows for comparison with more direct measurement methods and validation of the retrieval approach. Overall, the retrieved fine-mode fraction and effective radius compare well withmore » other in situ measurements, including size distribution measurements and scattering and absorption measurements made separately for PM 1 and PM 10, although there were some periods during which the different methods yielded different results. One key contributor to differences between the results obtained is the alternative, spectrally based definitions of fine and coarse modes from the optical methods, relative to instruments that use a physically defined cut point. These results indicate that for campaigns where size, composition and multi-wavelength optical property measurements are made, comparison of the results can result in closure or can identify unusual circumstances. The comparison here also demonstrates that in situ multi-wavelength optical property measurements can be used to determine information about particle size distributions in situations where direct size distribution measurements are not available.« less

Measuring dynamic kidney function in an undergraduate physiology laboratory.

PubMed

Medler, Scott; Harrington, Frederick

2013-12-01

Most undergraduate physiology laboratories are very limited in how they treat renal physiology. It is common to find teaching laboratories equipped with the capability for high-resolution digital recordings of physiological functions (muscle twitches, ECG, action potentials, respiratory responses, etc.), but most urinary laboratories still rely on a "dipstick" approach of urinalysis. Although this technique can provide some basic insights into the functioning of the kidneys, it overlooks the dynamic processes of filtration, reabsorption, and secretion. In the present article, we provide a straightforward approach of using renal clearance measurements to estimate glomerular filtration rate, fractional water reabsorption, glucose clearance, and other physiologically relevant parameters. The estimated values from our measurements in laboratory are in close agreement with those anticipated based on textbook parameters. For example, we found glomerular filtration rate to average 124 ± 45 ml/min, serum creatinine to be 1.23 ± 0.4 mg/dl, and fractional water reabsorption to be ∼96.8%. Furthermore, analyses for the class data revealed significant correlations between parameters like fractional water reabsorption and urine concentration, providing opportunities to discuss urine concentrating mechanisms and other physiological processes. The procedures outlined here are general enough that most undergraduate physiology laboratory courses should be able to implement them without difficulty.

Corneal birefringence measured by spectrally resolved Mueller matrix ellipsometry and implications for non-invasive glucose monitoring

PubMed Central

Westphal, Peter; Kaltenbach, Johannes-Maria; Wicker, Kai

2016-01-01

A good understanding of the corneal birefringence properties is essential for polarimetric glucose monitoring in the aqueous humor of the eye. Therefore, we have measured complete 16-element Mueller matrices of single-pass transitions through nine porcine corneas in-vitro, spectrally resolved in the range 300…1000 nm. These ellipsometric measurements have been performed at several angles of incidence at the apex and partially at the periphery of the corneas. The Mueller matrices have been decomposed into linear birefringence, circular birefringence (i.e. optical rotation), depolarization, and diattenuation. We found considerable circular birefringence, strongly increasing with decreasing wavelength, for most corneas. Furthermore, the decomposition revealed significant dependence of the linear retardance (in nm) on the wavelength below 500 nm. These findings suggest that uniaxial and biaxial crystals are insufficient models for a general description of the corneal birefringence, especially in the blue and in the UV spectral range. The implications on spectral-polarimetric approaches for glucose monitoring in the eye (for diabetics) are discussed. PMID:27446644

Measuring near infrared spectral reflectance changes from water stressed conifer stands with AIS-2

NASA Technical Reports Server (NTRS)

Riggs, George; Running, Steven W.

1987-01-01

Airborne Imaging Spectrometer-2 (AIS-2) data was acquired over two paired conifer stands for the purpose of detecting differences in spectral reflectance between stressed and natural canopies. Water stress was induced in a stand of Norway spruce and white pine by severing the sapwood near the ground. Water stress during the AIS flights was evaluated through shoot water potential and relative water content measurements. Preliminary analysis with raw AIS-2 data using SPAM indicates that there were small, inconsistent differences in absolute spectral reflectance in the near infrared 0.97 to 1.3 micron between the stressed and natural canopies.

Airborne Spectral Measurements of Surface-Atmosphere Anisotropy for Arctic Sea Ice and Tundra

NASA Technical Reports Server (NTRS)

Arnold, G. Thomas; Tsay, Si-Chee; King, Michael D.; Li, Jason Y.; Soulen, Peter F.

1999-01-01

Angular distributions of spectral reflectance for four common arctic surfaces: snow-covered sea ice, melt-season sea ice, snow-covered tundra, and tundra shortly after snowmelt were measured using an aircraft based, high angular resolution (1-degree) multispectral radiometer. Results indicate bidirectional reflectance is higher for snow-covered sea ice than melt-season sea ice at all wavelengths between 0.47 and 2.3 pm, with the difference increasing with wavelength. Bidirectional reflectance of snow-covered tundra is higher than for snow-free tundra for measurements less than 1.64 pm, with the difference decreasing with wavelength. Bidirectional reflectance patterns of all measured surfaces show maximum reflectance in the forward scattering direction of the principal plane, with identifiable specular reflection for the melt-season sea ice and snow-free tundra cases. The snow-free tundra had the most significant backscatter, and the melt-season sea ice the least. For sea ice, bidirectional reflectance changes due to snowmelt were more significant than differences among the different types of melt-season sea ice. Also the spectral-hemispherical (plane) albedo of each measured arctic surface was computed. Comparing measured nadir reflectance to albedo for sea ice and snow-covered tundra shows albedo underestimated 5-40%, with the largest bias at wavelengths beyond 1 pm. For snow-free tundra, nadir reflectance underestimates plane albedo by about 30-50%.

Determination of alloy content from plume spectral measurements

NASA Technical Reports Server (NTRS)

Madzsar, George C.

1991-01-01

The mathematical derivation for a method to determine the identities and amounts of alloys present in a flame where numerous alloys may be present is described. This method is applicable if the total number of elemental species from all alloys that may be in the flame is greater than or equal to the total number of alloys. Arranging the atomic spectral line emission equations for the elemental species as a series of simultaneous equations enables solution for identity and amount of the alloy present in the flame. This technique is intended for identification and quantification of alloy content in the plume of a rocket engine. Spectroscopic measurements reveal the atomic species entrained in the plume. Identification of eroding alloys may lead to the identification of the eroding component.

Remote sensing of St. Augustine Decline (SAD) disease. [spectral reflectance of healthy and diseased grass

NASA Technical Reports Server (NTRS)

Odle, W. C.

1976-01-01

Laboratory and field spectral reflectance measurements of healthy and infected St. Augustine grass were made using several different instruments. Spectral differences between healthy and infected grass occured in the visible and near infrared regions. Multiband and color infrared photographs were taken of healthy and diseased turf from ground-based platforms and low altitude aircraft. Qualitative (density slicing) and quantitative (transmission densitometry) analyses revealed distinct tonal differences between healthy and St. Augustine disease (SAD) infected grass. Similar experiments are described for determining if healthy and diseased grass can be distinguished from waterstressed grass and grass deficient in either nitrogen or iron.

Laboratory measurements and astronomical search for the HSO radical★★

PubMed Central

Cazzoli, Gabriele; Lattanzi, Valerio; Kirsch, Till; Gauss, Jürgen; Tercero, Belén; Cernicharo, José; Puzzarini, Cristina

2016-01-01

Context Despite the fact that many sulfur-bearing molecules, ranging from simple diatomic species up to astronomical complex molecules, have been detected in the interstellar medium, the sulfur chemistry in space is largely unknown and a depletion in the abundance of S-containing species has been observed in the cold, dense interstellar medium (ISM). The chemical form of the missing sulfur has yet to be identified. Aims For these reasons, in view of the fact that there is a large abundance of triatomic species harbouring sulfur, oxygen, and hydrogen, we decided to investigate the HSO radical in the laboratory to try its astronomical detection. Methods High-resolution measurements of the rotational spectrum of the HSO radical were carried out within a frequency range well up into the THz region. Subsequently, a rigorous search for HSO in the two most studied high-mass star-forming regions, Orion KL and Sagittarius (Sgr) B2, and in the cold dark cloud Barnard 1 (B1-b) was performed. Results The frequency coverage and the spectral resolution of our measurements allowed us to improve and extend the existing dataset of spectroscopic parameters, thus enabling accurate frequency predictions up to the THz range. These were used to derive the synthetic spectrum of HSO, by means of the MADEX code, according to the physical parameters of the astronomical source under consideration. For all sources investigated, the lack of HSO lines above the confusion limit of the data is evident. Conclusions The derived upper limit to the abundance of HSO clearly indicates that this molecule does not achieve significant abundances in either the gas phase or in the ice mantles of dust grains. PMID:27721513

High spectral resolution remote sensing of canopy chemistry

NASA Technical Reports Server (NTRS)

Aber, John D.; Martin, Mary E.

1995-01-01

Near infrared laboratory spectra have been used for many years to determine nitrogen and lignin concentrations in plant materials. In recent years, similar high spectral resolution visible and infrared data have been available via airborne remote sensing instruments. Using data from NASA's Airborne visible/Infrared Imaging Spectrometer (AVIRIS) we attempt to identify spectral regions correlated with foliar chemistry at the canopy level in temperate forests.

Method of multivariate spectral analysis

DOEpatents

Keenan, Michael R.; Kotula, Paul G.

2004-01-06

A method of determining the properties of a sample from measured spectral data collected from the sample by performing a multivariate spectral analysis. The method can include: generating a two-dimensional matrix A containing measured spectral data; providing a weighted spectral data matrix D by performing a weighting operation on matrix A; factoring D into the product of two matrices, C and S.sup.T, by performing a constrained alternating least-squares analysis of D=CS.sup.T, where C is a concentration intensity matrix and S is a spectral shapes matrix; unweighting C and S by applying the inverse of the weighting used previously; and determining the properties of the sample by inspecting C and S. This method can be used to analyze X-ray spectral data generated by operating a Scanning Electron Microscope (SEM) with an attached Energy Dispersive Spectrometer (EDS).

Achieving continuous improvement in laboratory organization through performance measurements: a seven-year experience.

PubMed

Salinas, Maria; López-Garrigós, Maite; Gutiérrez, Mercedes; Lugo, Javier; Sirvent, Jose Vicente; Uris, Joaquin

2010-01-01

Laboratory performance can be measured using a set of model key performance indicators (KPIs). The design and implementation of KPIs are important issues. KPI results from 7 years are reported and their implementation, monitoring, objectives, interventions, result reporting and delivery are analyzed. The KPIs of the entire laboratory process were obtained using Laboratory Information System (LIS) registers. These were collected automatically using a data warehouse application, spreadsheets and external quality program reports. Customer satisfaction was assessed using surveys. Nine model laboratory KPIs were proposed and measured. The results of some examples of KPIs used in our laboratory are reported. Their corrective measurements or the implementation of objectives led to improvement in the associated KPIs results. Measurement of laboratory performance using KPIs and a data warehouse application that continuously collects registers and calculates KPIs confirmed the reliability of indicators, indicator acceptability and usability for users, and continuous process improvement.

Latest developments at the ALBA magnetic measurements laboratory

NASA Astrophysics Data System (ADS)

Marcos, J.; Massana, V.; García, L.; Campmany, J.

2018-02-01

ALBA is a third-generation synchrotron light source that has been in operation since 2012 near Barcelona. A magnetic measurements laboratory has been associated with the facility since its very early stages and has been active for the last 20 years. In the first part of this work, the different instruments available at the laboratory are described, and a brief overview of the measurement campaigns carried out during its 20 years of history is presented. In the second part, a more detailed description of the approach to Hall probe measurements adopted at ALBA is offered, with an explanation of the methods and ancillary equipment that have been developed along the years in order to improve the accuracy of the system. In the third part, a new concept of Hall probe bench devoted to the measurement of closed structures is presented. The in-house design and building of a prototype for such a bench is described, together with its mechanical and magnetic characterization. As a conclusion, the first results obtained with this bench are discussed.

Hand-held radiometer red and photographic infrared spectral measurements of agricultural crops

NASA Technical Reports Server (NTRS)

Tucker, C. J.; Fan, C. J.; Elgin, J. H., Jr.; Mcmurtrey, J. E., III

1978-01-01

Red and photographic infrared radiance data, collected under a variety of conditions at weekly intervals throughout the growing season using a hand-held radiometer, were used to monitor crop growth and development. The vegetation index transformation was used to effectively compensate for the different irradiational conditions encountered during the study period. These data, plotted against time, compared the different crops measured by comparing their green leaf biomass dynamics. This approach, based entirely upon spectral inputs, closely monitors crop growth and development and indicates the promise of ground-based hand-held radiometer measurements of crops.

Measurement of refractive index of hemoglobin in the visible/NIR spectral range.

PubMed

Lazareva, Ekaterina N; Tuchin, Valery V

2018-03-01

This study is focused on the measurements of the refractive index of hemoglobin solutions in the visible/near-infrared (NIR) spectral range at room temperature for characteristic laser wavelengths: 480, 486, 546, 589, 644, 656, 680, 930, 1100, 1300, and 1550 nm. Measurements were performed using the multiwavelength Abbe refractometer. Aqua hemoglobin solutions of different concentrations obtained from human whole blood were investigated. The specific increment of refractive index on hemoglobin concentration and the Sellmeier coefficients were calculated. (2018) COPYRIGHT Society of Photo-Optical Instrumentation Engineers (SPIE).

Useful measures and models for analytical quality management in medical laboratories.

PubMed

Westgard, James O

2016-02-01

The 2014 Milan Conference "Defining analytical performance goals 15 years after the Stockholm Conference" initiated a new discussion of issues concerning goals for precision, trueness or bias, total analytical error (TAE), and measurement uncertainty (MU). Goal-setting models are critical for analytical quality management, along with error models, quality-assessment models, quality-planning models, as well as comprehensive models for quality management systems. There are also critical underlying issues, such as an emphasis on MU to the possible exclusion of TAE and a corresponding preference for separate precision and bias goals instead of a combined total error goal. This opinion recommends careful consideration of the differences in the concepts of accuracy and traceability and the appropriateness of different measures, particularly TAE as a measure of accuracy and MU as a measure of traceability. TAE is essential to manage quality within a medical laboratory and MU and trueness are essential to achieve comparability of results across laboratories. With this perspective, laboratory scientists can better understand the many measures and models needed for analytical quality management and assess their usefulness for practical applications in medical laboratories.

Spectral distortion of dual-comb spectrometry due to repetition rate fluctuation

NASA Astrophysics Data System (ADS)

Hong-Lei, Yang; Hao-Yun, Wei; Yan, Li

2016-04-01

Dual-comb spectrometry suffers the fluctuations of parameters in combs. We demonstrate that the repetition rate is more important than any other parameter, since the fluctuation of the repetition rate leads to a change of difference in the repetition rate between both combs, consequently causing the conversion factor variation and spectral frequency misalignment. The measured frequency noise power spectral density of the repetition rate exhibits an integrated residual frequency modulation of 1.4 Hz from 1 Hz to 100 kHz in our system. This value corresponds to the absorption peak fluctuation within a root mean square value of 0.19 cm-1 that is verified by both simulation and experimental result. Further, we can also simulate spectrum degradation as the fluctuation varies. After modifying misaligned spectra and averaging, the measured result agrees well with the simulated spectrum based on the GEISA database. Project supported by the State Key Laboratory of Precision Measurement Technology & Instruments of Tsinghua University and the Young Scientists Fund of the National Natural Science Foundation of China (Grant No. 61205147).

Broadband spectral shearing interferometry for amplitude and phase measurement of supercontinua

NASA Astrophysics Data System (ADS)

Dobner, S.; Brauckmann, N.; Kues, M.; Groß, P.; Fallnich, C.

2011-03-01

We present a new concept and the experimental realization of a customized spectral shearing interferometry for direct electric-field reconstruction (SPIDER) that is capable of measuring complex broadband laser pulses. The combination of an adapted broadband non-collinear phase matching geometry and the implementation of a home-built Fourier spectrometer enabled characterization of amplitude and phase of highly structured supercontinua with a bandwidth of more than 200 THz at pulse energies of less than 0.2 nJ.

Development of Jet Noise Power Spectral Laws Using SHJAR Data

NASA Technical Reports Server (NTRS)

Khavaran, Abbas; Bridges, James

2009-01-01

High quality jet noise spectral data measured at the Aeroacoustic Propulsion Laboratory at the NASA Glenn Research Center is used to examine a number of jet noise scaling laws. Configurations considered in the present study consist of convergent and convergent-divergent axisymmetric nozzles. Following the work of Viswanathan, velocity power factors are estimated using a least squares fit on spectral power density as a function of jet temperature and observer angle. The regression parameters are scrutinized for their uncertainty within the desired confidence margins. As an immediate application of the velocity power laws, spectral density in supersonic jets are decomposed into their respective components attributed to the jet mixing noise and broadband shock associated noise. Subsequent application of the least squares method on the shock power intensity shows that the latter also scales with some power of the shock parameter. A modified shock parameter is defined in order to reduce the dependency of the regression factors on the nozzle design point within the uncertainty margins of the least squares method.

Spectral Units on Europa and Ganymede

NASA Technical Reports Server (NTRS)

Mccord, T. B.; Nelson, M. L.; Clark, R. N.; Johnson, T. V.; Matson, D. L.; Johnson, R. E.; Boring, J.

1985-01-01

Comparisons of Europa and Ganymede multispectral data show that Ganymede is less spectrally variable than Europa. Four major spectral units dominate Ganymede, corresponding to the ancient cratered terrain and the grooved terrain in the leading and trailing hemispheres. A hemispheric asymmetry in UV absorption definitely exists on Ganymede, although it is not so strong as that on Europa. Comparison of normalized spectra for the four major units shows that the sense of the asymmetry (more absoption toward shorter wavelengths on the trailing hemisphere) is also the same on the two bodies. This hemispheric asymmetry is interpreted as evidence of alteration of the surface by magnetospheric bombardment or micrometorite bombardment. It is concluded that the pattern observed represents a steady state involving both of these exogenic modifying agents. The spectral changes which could be produced by these two processes are grain size alteration and changes in composition. The spectral effects of variation in water ice grain size are fairly well known. Laboratory experiments are being conducted to study the spectral effects of sulfur irradiation on water ice.

The Latest SORCE Solar Spectral Irradiance Data Release: Inter-Comparison and a First Look at TSIS SIM Measurement.

NASA Astrophysics Data System (ADS)

Beland, S.; Sandoval, L.; Vanier, B.; Elliott, J.; Harder, J. W.; Snow, M. A.; Woods, T. N.; Richard, E. C.; Pilewskie, P.

2017-12-01

The Spectral Irradiance Monitor (SIM), the SOLar STellar Irradiance Comparison Experiment (SOLSTICE), and the XUV Photometer System (XPS) instruments on board the Solar Radiation and Climate Experiment (SORCE) mission have been taking daily Solar spectral irradiance (SSI) measurements since April 2003. We present the latest data releases from these instruments, describing the improvements in the new datasets and the trends measured during Solar cycles 23 and 24. An inter-comparison of the SSI over the overlapping wavelengths for SIM and SOLSTICE is presented as well as, if the data is available, a comparison with the first light measurements from TSIS-SIM.

The measure of treatment agreement between portable and laboratory blood gas measurements in guiding protocol-driven ventilator management.

PubMed

Thomas, Frank O; Hoffman, Terri L; Handrahan, Diana L; Crapo, Robert O; Snow, Greg

2009-08-01

Portable blood gas analyzer and monitor devices are increasingly being used to direct ventilator therapy. The purpose of this study was to evaluate the "measure of treatment agreement" between portable and laboratory blood gas measurements used in guiding protocol-driven ventilator management. Using National Institutes of Health Acute Respiratory Distress Syndrome network ventilator management guidelines to manage patient care, measurements taken from the Nonin 8500 M pulse oximeter (SpO2), the Novametrix-610 end-tidal CO2 (ETCO2) detector, and the i-STAT 1 (SaO2, PO2, pH, PCO2) were compared with the recommended treatment from paired laboratory ABL-725 (SaCO2, PO2, pH, PCO2) measurements. Four hundred forty-six intubated adult intensive care unit patients were studied prospectively. Except for the ETCO2 (R2 = 0.460), correlation coefficients between portable and laboratory measurements were high (R2 > or = 0.755). Testing for equivalence, the Nonin-SpO2, iSTAT-PO2, iSTAT-pH, and iSTAT-PCO2 were deemed "equivalent" surrogates to paired ABL measurements. Testing for the limits of agreement found only the iSTAT-PCO2 to be an acceptable surrogate measurement. The measure of treatment agreement between the portable and paired laboratory blood gas measurements were Nonin-SpO2 (68%), iSTAT-SaO2 (73%), iSTAT-PO2 (97%), iSTAT-pH (88%), iSTAT-PCO2 (95%), and Novametrix-ETCO2 (60%). Only the iSTAT-PO2 and the iSTAT-PCO2 achieved the > or =95% treatment agreement threshold to be considered as acceptable surrogates to laboratory measurements. : The iSTAT-PO2 and -PCO2 were portable device measurements acceptable as surrogates to standard clinical laboratory blood gas measurements in guiding protocol-directed ventilator management. The "measure of treatment agreement," based on standardized decisions and measurement thresholds of a protocol, provides a simple method for assessing clinical validity of surrogate measurements.

Assessing the high frequency behavior of non-polarizable electrodes for spectral induced polarization measurements

NASA Astrophysics Data System (ADS)

Abdulsamad, Feras; Florsch, Nicolas; Schmutz, Myriam; Camerlynck, Christian

2016-12-01

During the last decades, the usage of spectral induced polarization (SIP) measurements in hydrogeology and detecting environmental problems has been extensively increased. However, the physical mechanisms which are responsible for the induced polarization response over the usual frequency range (typically 1 mHz to 10-20 kHz) require better understanding. The phase shift observed at high frequencies is sometimes attributed to the so-called Maxwell-Wagner polarization which takes place when charges cross an interface. However, SIP measurements of tap water show a phase shift at frequencies higher than 1 kHz, where no Maxwell-Wagner polarization may occur. In this paper, we enlighten the possible origin of this phase shift and deduce its likely relationship with the types of the measuring electrodes. SIP Laboratory measurements of tap water using different types of measuring electrodes (polarizable and non-polarizable electrodes) are carried out to detect the origin of the phase shift at high frequencies and the influence of the measuring electrodes types on the observed complex resistivity. Sodium chloride is used to change the conductivity of the medium in order to quantify the solution conductivity role. The results of these measurements are clearly showing the impact of the measuring electrodes type on the measured phase spectrum while the influence on the amplitude spectrum is negligible. The phenomenon appearing on the phase spectrum at high frequency (> 1 kHz) whatever the electrode type is, the phase shows an increase compared to the theoretical response, and the discrepancy (at least in absolute value) increases with frequency, but it is less severe when medium conductivity is larger. Additionally, the frequency corner is shifted upward in frequency. The dependence of this phenomenon on the conductivity and the measuring electrodes type (electrode-electrolyte interface) seems to be due to some dielectric effects (as an electrical double layer of small

Uncertainty evaluation of thickness and warp of a silicon wafer measured by a spectrally resolved interferometer

NASA Astrophysics Data System (ADS)

Praba Drijarkara, Agustinus; Gergiso Gebrie, Tadesse; Lee, Jae Yong; Kang, Chu-Shik

2018-06-01

Evaluation of uncertainty of thickness and gravity-compensated warp of a silicon wafer measured by a spectrally resolved interferometer is presented. The evaluation is performed in a rigorous manner, by analysing the propagation of uncertainty from the input quantities through all the steps of measurement functions, in accordance with the ISO Guide to the Expression of Uncertainty in Measurement. In the evaluation, correlation between input quantities as well as uncertainty attributed to thermal effect, which were not included in earlier publications, are taken into account. The temperature dependence of the group refractive index of silicon was found to be nonlinear and varies widely within a wafer and also between different wafers. The uncertainty evaluation described here can be applied to other spectral interferometry applications based on similar principles.

Spectro-polarimetry of Ice-dust Mixtures measured in the Laboratory with Application to the Solar System and Beyond

NASA Astrophysics Data System (ADS)

Poch, O.; Schmid, H. M.; Pommerol, A.; Jost, B.; Brouet, Y.; Thomas, N.

2015-12-01

Polarimetric observations of atmosphere-less Solar System bodies can give clues on the texture and on the physico-chemical composition of their surfaces, as reviewed by Mishchenko et al. (2010) and Bagnulo et al. (2011). Measurements performed in the laboratory on carefully characterized samples can provide reference data that can be used for direct comparison with remote-sensing polarimetric observations. In particular, we want to study the spectral dependence of the polarization and the way it is correlated or not with the surface albedo. In the Laboratory for Outflow Studies of Sublimating Materials (LOSSy) at the University of Bern, we have developed the capability to prepare and analyze optically thick analogues of planetary or cometary surfaces composed of water ice, minerals and carbonaceous compounds. Water-free dust of high porosity can also be produced by sublimation of ice under space-simulated conditions (Pommerol et al., 2015). Here, we present the first results of polarization measurements performed in the LOSSy. A Stokes polarimeter is used to measure the Stokes parameters describing the polarization of the visible light scattered by icy samples illuminated with a randomly polarized light simulating the star light. Additionally, a radio-goniometer, equipped with polarizers, can also measure the phase angle dependence of the linearly polarized scattered light. These measurements could provide interesting inputs to complement the theoretical models and predict or interpret spectro-polarimetric properties of Solar System objects and circumstellar disks. Mishchenko, M., et al., 2010, Polarimetric Remote Sensing of Solar System Objects. Bagnulo, S., et al., 2011, J. Quant. Spectrosc. Ra. 112, 2059. Pommerol, A., et al., 2015, Planet. Space Sci. 109-110, 106-122.

Solar Confocal interferometers for Sub-Picometer-Resolution Spectral Filters

NASA Technical Reports Server (NTRS)

Gary, G. Allen; Pietraszewski, Chris; West, Edward A.; Dines. Terence C.

2007-01-01

The confocal Fabry-Perot interferometer allows sub-picometer spectral resolution of Fraunhofer line profiles. Such high spectral resolution is needed to keep pace with the higher spatial resolution of the new set of large-aperture solar telescopes. The line-of-sight spatial resolution derived for line profile inversions would then track the improvements of the transverse spatial scale provided by the larger apertures. In particular, profile inversion allows improved velocity and magnetic field gradients to be determined independent of multiple line analysis using different energy levels and ions. The confocal interferometer's unique properties allow a simultaneous increase in both etendue and spectral power. The higher throughput for the interferometer provides significant decrease in the aperture, which is important in spaceflight considerations. We have constructed and tested two confocal interferometers. A slow-response thermal-controlled interferometer provides a stable system for laboratory investigation, while a piezoelectric interferometer provides a rapid response for solar observations. In this paper we provide design parameters, show construction details, and report on the laboratory test for these interferometers. The field of view versus aperture for confocal interferometers is compared with other types of spectral imaging filters. We propose a multiple etalon system for observing with these units using existing planar interferometers as pre-filters. The radiometry for these tests established that high spectral resolution profiles can be obtained with imaging confocal interferometers. These sub-picometer spectral data of the photosphere in both the visible and near-infrared can provide important height variation information. However, at the diffraction-limited spatial resolution of the telescope, the spectral data is photon starved due to the decreased spectral passband.

Assessing FRET using Spectral Techniques

PubMed Central

Leavesley, Silas J.; Britain, Andrea L.; Cichon, Lauren K.; Nikolaev, Viacheslav O.; Rich, Thomas C.

2015-01-01

Förster resonance energy transfer (FRET) techniques have proven invaluable for probing the complex nature of protein–protein interactions, protein folding, and intracellular signaling events. These techniques have traditionally been implemented with the use of one or more fluorescence band-pass filters, either as fluorescence microscopy filter cubes, or as dichroic mirrors and band-pass filters in flow cytometry. In addition, new approaches for measuring FRET, such as fluorescence lifetime and acceptor photobleaching, have been developed. Hyperspectral techniques for imaging and flow cytometry have also shown to be promising for performing FRET measurements. In this study, we have compared traditional (filter-based) FRET approaches to three spectral-based approaches: the ratio of acceptor-to-donor peak emission, linear spectral unmixing, and linear spectral unmixing with a correction for direct acceptor excitation. All methods are estimates of FRET efficiency, except for one-filter set and three-filter set FRET indices, which are included for consistency with prior literature. In the first part of this study, spectrofluorimetric data were collected from a CFP–Epac–YFP FRET probe that has been used for intracellular cAMP measurements. All comparisons were performed using the same spectrofluorimetric datasets as input data, to provide a relevant comparison. Linear spectral unmixing resulted in measurements with the lowest coefficient of variation (0.10) as well as accurate fits using the Hill equation. FRET efficiency methods produced coefficients of variation of less than 0.20, while FRET indices produced coefficients of variation greater than 8.00. These results demonstrate that spectral FRET measurements provide improved response over standard, filter-based measurements. Using spectral approaches, single-cell measurements were conducted through hyperspectral confocal microscopy, linear unmixing, and cell segmentation with quantitative image analysis

Assessing FRET using spectral techniques.

PubMed

Leavesley, Silas J; Britain, Andrea L; Cichon, Lauren K; Nikolaev, Viacheslav O; Rich, Thomas C

2013-10-01

Förster resonance energy transfer (FRET) techniques have proven invaluable for probing the complex nature of protein-protein interactions, protein folding, and intracellular signaling events. These techniques have traditionally been implemented with the use of one or more fluorescence band-pass filters, either as fluorescence microscopy filter cubes, or as dichroic mirrors and band-pass filters in flow cytometry. In addition, new approaches for measuring FRET, such as fluorescence lifetime and acceptor photobleaching, have been developed. Hyperspectral techniques for imaging and flow cytometry have also shown to be promising for performing FRET measurements. In this study, we have compared traditional (filter-based) FRET approaches to three spectral-based approaches: the ratio of acceptor-to-donor peak emission, linear spectral unmixing, and linear spectral unmixing with a correction for direct acceptor excitation. All methods are estimates of FRET efficiency, except for one-filter set and three-filter set FRET indices, which are included for consistency with prior literature. In the first part of this study, spectrofluorimetric data were collected from a CFP-Epac-YFP FRET probe that has been used for intracellular cAMP measurements. All comparisons were performed using the same spectrofluorimetric datasets as input data, to provide a relevant comparison. Linear spectral unmixing resulted in measurements with the lowest coefficient of variation (0.10) as well as accurate fits using the Hill equation. FRET efficiency methods produced coefficients of variation of less than 0.20, while FRET indices produced coefficients of variation greater than 8.00. These results demonstrate that spectral FRET measurements provide improved response over standard, filter-based measurements. Using spectral approaches, single-cell measurements were conducted through hyperspectral confocal microscopy, linear unmixing, and cell segmentation with quantitative image analysis. Results from

Spectral Measurements of Alpha-induced Radioluminescence in Various Gases

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

Brett, Jaclyn; Koehler, Katrina Elizabeth; Bischak, Michael

Radioluminescent emission in Ar, N 2, O 2, and dry air at P=1 atm was observed induced by 5 MeV α particles. The wavelength range with a single detector spanned 250–1100 nm, extending the range well into the UV and IR bands with a single detector. Measured spectral lines for alpha-induced luminescence were corrected for detector transmission and intensities compared to previous work. The exploration of multiple gases over a wide frequency range opens the door to security and remote sensing applications, where different environments are routinely encountered. Finally, this work provides spectra that can be used in guiding futuremore » filter development focusing on remote alpha detection.« less

Spectral Measurements of Alpha-induced Radioluminescence in Various Gases

DOE PAGES

Brett, Jaclyn; Koehler, Katrina Elizabeth; Bischak, Michael; ...

2017-09-06

Radioluminescent emission in Ar, N 2, O 2, and dry air at P=1 atm was observed induced by 5 MeV α particles. The wavelength range with a single detector spanned 250–1100 nm, extending the range well into the UV and IR bands with a single detector. Measured spectral lines for alpha-induced luminescence were corrected for detector transmission and intensities compared to previous work. The exploration of multiple gases over a wide frequency range opens the door to security and remote sensing applications, where different environments are routinely encountered. Finally, this work provides spectra that can be used in guiding futuremore » filter development focusing on remote alpha detection.« less

Channeled polarimetric technique for the measurement of spectral dependence of linearly Stokes parameters

NASA Astrophysics Data System (ADS)

Quan, Naicheng; Zhang, Chunmin; Mu, Tingkui; Li, Qiwei

2018-05-01

The principle and experimental demonstration of a method based on channeled polarimetric technique (CPT) to measure spectrally resolved linearly Stokes parameters (SRLS) is presented. By replacing front retarder with an achromatic quarter wave-plate of CPT, the linearly SRLS can be measured simultaneously. It also retains the advantages of static and compact of CPT. Besides, comparing with CPT, it can reduce the RMS error by nearly a factor of 2-5 for the individual linear Stokes parameters.

Adaption of an array spectroradiometer for total ozone column retrieval using direct solar irradiance measurements in the UV spectral range

NASA Astrophysics Data System (ADS)

Zuber, Ralf; Sperfeld, Peter; Riechelmann, Stefan; Nevas, Saulius; Sildoja, Meelis; Seckmeyer, Gunther

2018-04-01

A compact array spectroradiometer that enables precise and robust measurements of solar UV spectral direct irradiance is presented. We show that this instrument can retrieve total ozone column (TOC) accurately. The internal stray light, which is often the limiting factor for measurements in the UV spectral range and increases the uncertainty for TOC analysis, is physically reduced so that no other stray-light reduction methods, such as mathematical corrections, are necessary. The instrument has been extensively characterised at the Physikalisch-Technische Bundesanstalt (PTB) in Germany. During an international total ozone measurement intercomparison at the Izaña Atmospheric Observatory in Tenerife, the high-quality applicability of the instrument was verified with measurements of the direct solar irradiance and subsequent TOC evaluations based on the spectral data measured between 12 and 30 September 2016. The results showed deviations of the TOC of less than 1.5 % from most other instruments in most situations and not exceeding 3 % from established TOC measurement systems such as Dobson or Brewer.

Numerical modeling of zero-offset laboratory data in a strong topographic environment: results for a spectral-element method and a discretized Kirchhoff integral method

NASA Astrophysics Data System (ADS)

Favretto-Cristini, Nathalie; Tantsereva, Anastasiya; Cristini, Paul; Ursin, Bjørn; Komatitsch, Dimitri; Aizenberg, Arkady M.

2014-08-01

Accurate simulation of seismic wave propagation in complex geological structures is of particular interest nowadays. However conventional methods may fail to simulate realistic wavefields in environments with great and rapid structural changes, due for instance to the presence of shadow zones, diffractions and/or edge effects. Different methods, developed to improve seismic modeling, are typically tested on synthetic configurations against analytical solutions for simple canonical problems or reference methods, or via direct comparison with real data acquired in situ. Such approaches have limitations, especially if the propagation occurs in a complex environment with strong-contrast reflectors and surface irregularities, as it can be difficult to determine the method which gives the best approximation of the "real" solution, or to interpret the results obtained without an a priori knowledge of the geologic environment. An alternative approach for seismics consists in comparing the synthetic data with high-quality data collected in laboratory experiments under controlled conditions for a known configuration. In contrast with numerical experiments, laboratory data possess many of the characteristics of field data, as real waves propagate through models with no numerical approximations. We thus present a comparison of laboratory-scaled measurements of 3D zero-offset wave reflection of broadband pulses from a strong topographic environment immersed in a water tank with numerical data simulated by means of a spectral-element method and a discretized Kirchhoff integral method. The results indicate a good quantitative fit in terms of time arrivals and acceptable fit in amplitudes for all datasets.

Hydrocarbon Spectral Database

National Institute of Standards and Technology Data Gateway

SRD 115 Hydrocarbon Spectral Database (Web, free access)   All of the rotational spectral lines observed and reported in the open literature for 91 hydrocarbon molecules have been tabulated. The isotopic molecular species, assigned quantum numbers, observed frequency, estimated measurement uncertainty and reference are given for each transition reported.

Diatomic Spectral Database

National Institute of Standards and Technology Data Gateway

SRD 114 Diatomic Spectral Database (Web, free access)   All of the rotational spectral lines observed and reported in the open literature for 121 diatomic molecules have been tabulated. The isotopic molecular species, assigned quantum numbers, observed frequency, estimated measurement uncertainty, and reference are given for each transition reported.

Triatomic Spectral Database

National Institute of Standards and Technology Data Gateway

SRD 117 Triatomic Spectral Database (Web, free access)   All of the rotational spectral lines observed and reported in the open literature for 55 triatomic molecules have been tabulated. The isotopic molecular species, assigned quantum numbers, observed frequency, estimated measurement uncertainty and reference are given for each transition reported.

Water vapour foreign-continuum absorption in near-infrared windows from laboratory measurements.

PubMed

Ptashnik, Igor V; McPheat, Robert A; Shine, Keith P; Smith, Kevin M; Williams, R Gary

2012-06-13

For a long time, it has been believed that atmospheric absorption of radiation within wavelength regions of relatively high infrared transmittance (so-called 'windows') was dominated by the water vapour self-continuum, that is, spectrally smooth absorption caused by H(2)O--H(2)O pair interaction. Absorption due to the foreign continuum (i.e. caused mostly by H(2)O--N(2) bimolecular absorption in the Earth's atmosphere) was considered to be negligible in the windows. We report new retrievals of the water vapour foreign continuum from high-resolution laboratory measurements at temperatures between 350 and 430 K in four near-infrared windows between 1.1 and 5 μm (9000-2000 cm(-1)). Our results indicate that the foreign continuum in these windows has a very weak temperature dependence and is typically between one and two orders of magnitude stronger than that given in representations of the continuum currently used in many climate and weather prediction models. This indicates that absorption owing to the foreign continuum may be comparable to the self-continuum under atmospheric conditions in the investigated windows. The calculated global-average clear-sky atmospheric absorption of solar radiation is increased by approximately 0.46 W m(-2) (or 0.6% of the total clear-sky absorption) by using these new measurements when compared with calculations applying the widely used MTCKD (Mlawer-Tobin-Clough-Kneizys-Davies) foreign-continuum model.

Laboratory Measurements of the K-Shell Transition Energies in L-Shell Ions of Si and S

NASA Technical Reports Server (NTRS)

Hell, N.; Brown, G.V.; Wilms, J.; Grinberg, V.; Clementson, J.; Liedahl, D.; Porter, F. S.; Kelley, R. L.; Kilbourne, C. A.; Beiersrdorfer, P.

2016-01-01

We have measured the energies of the strongest 1s-2 l (azimuthal quantum number) (l = s, p (s, p are angular momentum states)) transitions in He- through Ne-like silicon and sulfur ions to an accuracy of less than 1 electronvolt using the Lawrence Livermore National Laboratory's electron beam ion traps, EBIT-I and SuperEBIT, and the NASA/GSFC EBIT Calorimeter Spectrometer (ECS). We identify and measure the energies of 18 and 21 X-ray features from silicon and sulfur, respectively. The results are compared to new Flexible Atomic Code calculations and to semi-relativistic Hartree-Fock calculations by Palmeri et al. (2008). These results will be especially useful for wind diagnostics in high-mass X-ray binaries, such as Vela X-1 and Cygnus X-1, where high-resolution spectral measurements using Chandra's high-energy transmission grating has made it possible to measure Doppler shifts of 100 kilometers per second. The accuracy of our measurements is consistent with that needed to analyze Chandra observations, exceeding Chandra's 100 kilometers per second limit. Hence, the results presented here not only provide benchmarks for theory, but also accurate rest energies that can be used to determine the bulk motion of material in astrophysical sources. We show the usefulness of our results by applying them to redetermine Doppler shifts from Chandra observations of Vela X-1.

Spectral Aerosol Extinction (SpEx): A New Instrument for In situ Ambient Aerosol Extinction Measurements Across the UV/Visible Wavelength Range

NASA Technical Reports Server (NTRS)

Jordan, C. E.; Anderson, B. E.; Beyersdorf, A. J.; Corr, C. A.; Dibb, J. E.; Greenslade, M. E.; Martin, R. F.; Moore, R. H.; Scheuer, E.; Shook, M. A.;

Modeling of spectral signatures of littoral waters

NASA Astrophysics Data System (ADS)

Haltrin, Vladimir I.

1997-12-01

The spectral values of remotely obtained radiance reflectance coefficient (RRC) are compared with the values of RRC computed from inherent optical properties measured during the shipborne experiment near the West Florida coast. The model calculations are based on the algorithm developed at the Naval Research Laboratory at Stennis Space Center and presented here. The algorithm is based on the radiation transfer theory and uses regression relationships derived from experimental data. Overall comparison of derived and measured RRCs shows that this algorithm is suitable for processing ground truth data for the purposes of remote data calibration. The second part of this work consists of the evaluation of the predictive visibility model (PVM). The simulated three-dimensional values of optical properties are compared with the measured ones. Preliminary results of comparison are encouraging and show that the PVM can qualitatively predict the evolution of inherent optical properties in littoral waters.

Comparing auditory filter bandwidths, spectral ripple modulation detection, spectral ripple discrimination, and speech recognition: Normal and impaired hearinga)

PubMed Central

Davies-Venn, Evelyn; Nelson, Peggy; Souza, Pamela

2015-01-01

Some listeners with hearing loss show poor speech recognition scores in spite of using amplification that optimizes audibility. Beyond audibility, studies have suggested that suprathreshold abilities such as spectral and temporal processing may explain differences in amplified speech recognition scores. A variety of different methods has been used to measure spectral processing. However, the relationship between spectral processing and speech recognition is still inconclusive. This study evaluated the relationship between spectral processing and speech recognition in listeners with normal hearing and with hearing loss. Narrowband spectral resolution was assessed using auditory filter bandwidths estimated from simultaneous notched-noise masking. Broadband spectral processing was measured using the spectral ripple discrimination (SRD) task and the spectral ripple depth detection (SMD) task. Three different measures were used to assess unamplified and amplified speech recognition in quiet and noise. Stepwise multiple linear regression revealed that SMD at 2.0 cycles per octave (cpo) significantly predicted speech scores for amplified and unamplified speech in quiet and noise. Commonality analyses revealed that SMD at 2.0 cpo combined with SRD and equivalent rectangular bandwidth measures to explain most of the variance captured by the regression model. Results suggest that SMD and SRD may be promising clinical tools for diagnostic evaluation and predicting amplification outcomes. PMID:26233047

Comparing auditory filter bandwidths, spectral ripple modulation detection, spectral ripple discrimination, and speech recognition: Normal and impaired hearing.

PubMed

Davies-Venn, Evelyn; Nelson, Peggy; Souza, Pamela

2015-07-01

Some listeners with hearing loss show poor speech recognition scores in spite of using amplification that optimizes audibility. Beyond audibility, studies have suggested that suprathreshold abilities such as spectral and temporal processing may explain differences in amplified speech recognition scores. A variety of different methods has been used to measure spectral processing. However, the relationship between spectral processing and speech recognition is still inconclusive. This study evaluated the relationship between spectral processing and speech recognition in listeners with normal hearing and with hearing loss. Narrowband spectral resolution was assessed using auditory filter bandwidths estimated from simultaneous notched-noise masking. Broadband spectral processing was measured using the spectral ripple discrimination (SRD) task and the spectral ripple depth detection (SMD) task. Three different measures were used to assess unamplified and amplified speech recognition in quiet and noise. Stepwise multiple linear regression revealed that SMD at 2.0 cycles per octave (cpo) significantly predicted speech scores for amplified and unamplified speech in quiet and noise. Commonality analyses revealed that SMD at 2.0 cpo combined with SRD and equivalent rectangular bandwidth measures to explain most of the variance captured by the regression model. Results suggest that SMD and SRD may be promising clinical tools for diagnostic evaluation and predicting amplification outcomes.

Spectral Reflectance Measurement of Evaporating Chemical Films: Initial Results and Application to Skin Permeation.

PubMed

Frasch, H Frederick; Lee, Larry; Barbero, Ana M

2018-04-27

The current study has two aims. First the method of spectral reflectance was used to measure evaporation rates of thin (∼25-300 μm) films of neat liquid volatile organic chemicals exposed to a well-regulated wind speed u. Gas phase evaporation mass transfer coefficient (k evap ) measurements of 10 chemicals, 9 of which were measured at similar u, are predicted (slope of log-log data = 1.01; intercept = 0.08; R 2 = 0.996) by a previously proposed mass transfer correlation. For one chemical, isoamyl alcohol, the dependence of k evap on u 0.52 was measured, in support of the predicted exponent value of ½. Second, measured k evap of nicotine was used as an input in analytical models based on diffusion theory to estimate the absorbed fraction (F abs ) of a small dose (5 μL/cm 2 ) applied to human epidermis in vitro. The measured F abs was 0.062 ± 0.023. Model-estimated values are 0.066 and 0.115. Spectral reflectance is a precise method of measuring k evap of liquid chemicals and the data are well-described by a simple gas phase mass transfer coefficient. For nicotine under the single exposure condition measured herein, F abs is well-predicted from a theoretical model that requires knowledge of k evap , maximal dermal flux and membrane lag time. Copyright © 2018. Published by Elsevier Inc.

Measurement of the Spatial Distribution of the Spectral Response Variation in the Field of View of the ASD Spectrometer Input Optics

DTIC Science & Technology

2014-12-01

development. It will be used for the measurement of the spectro-polarimetric BRDF (Bidirectional Reflectance Distribution function). For practical reasons...goniomètre est en développement. Il sera utilisé pour les mesures de BRDF (fonction de distribution de réflectance bidirectionnelle) spectrales et...by the independent measurements of the spectral and Bidirectional Reflectance Distribution Function ( BRDF ). The BRDF is the measurement of the

High-resolution grazing-incidence grating spectrometer for temperature measurements of low-Z ions emitting in the 100–300 Å spectral band

DOE PAGES

Widmann, K.; Beiersdorfer, P.; Magee, E. W.; ...

2014-09-19

In this paper, we have constructed a high-resolution grazing-incidence spectrometer designed for measuring the ion temperature of low-Z elements, such as Li + or Li 2 +, which radiate near 199 Å and 135 Å, respectively. Based on measurements at the Livermore Electron Beam Ion Trap we have shown that the instrumental resolution is better than 48 mÅ at the 200 Å setting and better than 40 mÅ for the 135-Å range. Such a high spectral resolution corresponds to an instrumental limit for line-width based temperature measurements of about 45 eV for the 199 Å Li+ and 65 eV formore » the 135 Å Li 2 + lines. Finally, recently obtained survey spectra from the Lithium Tokamak Experiment at the Princeton Plasma Physics Laboratory show the presence of these lithium emission lines and the expected core ion temperature of approximately 70 eV is sufficiently high to demonstrate the feasibility of utilizing our high-resolution spectrometer as an ion-temperature diagnostic.« less

Spectral CT Reconstruction with Image Sparsity and Spectral Mean

PubMed Central

Zhang, Yi; Xi, Yan; Yang, Qingsong; Cong, Wenxiang; Zhou, Jiliu

2017-01-01

Photon-counting detectors can acquire x-ray intensity data in different energy bins. The signal to noise ratio of resultant raw data in each energy bin is generally low due to the narrow bin width and quantum noise. To address this problem, here we propose an image reconstruction approach for spectral CT to simultaneously reconstructs x-ray attenuation coefficients in all the energy bins. Because the measured spectral data are highly correlated among the x-ray energy bins, the intra-image sparsity and inter-image similarity are important prior acknowledge for image reconstruction. Inspired by this observation, the total variation (TV) and spectral mean (SM) measures are combined to improve the quality of reconstructed images. For this purpose, a linear mapping function is used to minimalize image differences between energy bins. The split Bregman technique is applied to perform image reconstruction. Our numerical and experimental results show that the proposed algorithms outperform competing iterative algorithms in this context. PMID:29034267

Versatile light-emitting-diode-based spectral response measurement system for photovoltaic device characterization.

PubMed

Hamadani, Behrang H; Roller, John; Dougherty, Brian; Yoon, Howard W

2012-07-01

An absolute differential spectral response measurement system for solar cells is presented. The system couples an array of light emitting diodes with an optical waveguide to provide large area illumination. Two unique yet complementary measurement methods were developed and tested with the same measurement apparatus. Good agreement was observed between the two methods based on testing of a variety of solar cells. The first method is a lock-in technique that can be performed over a broad pulse frequency range. The second method is based on synchronous multifrequency optical excitation and electrical detection. An innovative scheme for providing light bias during each measurement method is discussed.

Archiving Spectral Libraries in the Planetary Data System

NASA Astrophysics Data System (ADS)

Slavney, S.; Guinness, E. A.; Scholes, D.; Zastrow, A.

2017-12-01

Spectral libraries are becoming popular candidates for archiving in PDS. With the increase in the number of individual investigators funded by programs such as NASA's PDART, the PDS Geosciences Node is receiving many requests for support from proposers wishing to archive various forms of laboratory spectra. To accommodate the need for a standardized approach to archiving spectra, the Geosciences Node has designed the PDS Spectral Library Data Dictionary, which contains PDS4 classes and attributes specifically for labeling spectral data, including a classification scheme for samples. The Reflectance Experiment Laboratory (RELAB) at Brown University, which has long been a provider of spectroscopy equipment and services to the science community, has provided expert input into the design of the dictionary. Together the Geosciences Node and RELAB are preparing the whole of the RELAB Spectral Library, consisting of many thousands of spectra collected over the years, to be archived in PDS. An online interface for searching, displaying, and downloading selected spectra is planned, using the Spectral Library metadata recorded in the PDS labels. The data dictionary and online interface will be extended to include spectral libraries submitted by other data providers. The Spectral Library Data Dictionary is now available from PDS at https://pds.nasa.gov/pds4/schema/released/. It can be used in PDS4 labels for reflectance spectra as well as for Raman, XRF, XRD, LIBS, and other types of spectra. Ancillary data such as images, chemistry, and abundance data are also supported. To help generate PDS4-compliant labels for spectra, the Geosciences Node provides a label generation program called MakeLabels (http://pds-geosciences.wustl.edu/tools/makelabels.html) which creates labels from a template, and which can be used for any kind of PDS4 label. For information, contact the Geosciences Node at geosci@wunder.wustl.edu.

Spectral and temperature-dependent infrared emissivity measurements of painted metals for improved temperature estimation during laser damage testing

NASA Astrophysics Data System (ADS)

Baumann, Sean M.; Keenan, Cameron; Marciniak, Michael A.; Perram, Glen P.

2014-10-01

A database of spectral and temperature-dependent emissivities was created for painted Al-alloy laser-damage-testing targets for the purpose of improving the uncertainty to which temperature on the front and back target surfaces may be estimated during laser-damage testing. Previous temperature estimates had been made by fitting an assumed gray-body radiance curve to the calibrated spectral radiance data collected from the back surface using a Telops Imaging Fourier Transform Spectrometer (IFTS). In this work, temperature-dependent spectral emissivity measurements of the samples were made from room temperature to 500 °C using a Surface Optics Corp. SOC-100 Hemispherical Directional Reflectometer (HDR) with Nicolet FTS. Of particular interest was a high-temperature matte-black enamel paint used to coat the rear surfaces of the Al-alloy samples. The paint had been assumed to have a spectrally flat and temperatureinvariant emissivity. However, the data collected using the HDR showed both spectral variation and temperature dependence. The uncertainty in back-surface temperature estimation during laser-damage testing made using the measured emissivities was improved from greater than +10 °C to less than +5 °C for IFTS pixels away from the laser burn-through hole, where temperatures never exceeded those used in the SOC-100 HDR measurements. At beam center, where temperatures exceeded those used in the SOC-100 HDR, uncertainty in temperature estimates grew beyond those made assuming gray-body emissivity. Accurate temperature estimations during laser-damage testing are useful in informing a predictive model for future high-energy-laser weapon applications.

Environmental Measurements Laboratory fiscal year 1998: Accomplishments and technical activities

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

Erickson, M.D.

1999-01-01

The Environmental Measurements Laboratory (EML) is government-owned, government-operated, and programmatically under the DOE Office of Environmental Management. The Laboratory is administered by the Chicago Operations Office. EML provides program management, technical assistance and data quality assurance for measurements of radiation and radioactivity relating to environmental restoration, global nuclear nonproliferation, and other priority issues for the Department of Energy, as well as for other government, national, and international organizations. This report presents the technical activities and accomplishments of EML for Fiscal Year 1998.

Beyond CCT: The spectral index system as a tool for the objective, quantitative characterization of lamps

NASA Astrophysics Data System (ADS)

Galadí-Enríquez, D.

2018-02-01

Correlated color temperature (CCT) is a semi-quantitative system that roughly describes the spectra of lamps. This parameter gives the temperature (measured in kelvins) of the black body that would show the hue more similar to that of the light emitted by the lamp. Modern lamps for indoor and outdoor lighting display many spectral energy distributions, most of them extremely different to those of black bodies, what makes CCT to be far from a perfect descriptor from the physical point of view. The spectral index system presented in this work provides an accurate, objective, quantitative procedure to characterize the spectral properties of lamps, with just a few numbers. The system is an adaptation to lighting technology of the classical procedures of multi-band astronomical photometry with wide and intermediate-band filters. We describe the basic concepts and we apply the system to a representative set of lamps of many kinds. The results lead to interesting, sometimes surprising conclusions. The spectral index system is extremely easy to implement from the spectral data that are routinely measured at laboratories. Thus, including this kind of computations in the standard protocols for the certification of lamps will be really straightforward, and will enrich the technical description of lighting devices.

USGS Digital Spectral Library splib06a

USGS Publications Warehouse

Clark, Roger N.; Swayze, Gregg A.; Wise, Richard A.; Livo, K. Eric; Hoefen, Todd M.; Kokaly, Raymond F.; Sutley, Stephen J.

2007-01-01

Introduction We have assembled a digital reflectance spectral library that covers the wavelength range from the ultraviolet to far infrared along with sample documentation. The library includes samples of minerals, rocks, soils, physically constructed as well as mathematically computed mixtures, plants, vegetation communities, microorganisms, and man-made materials. The samples and spectra collected were assembled for the purpose of using spectral features for the remote detection of these and similar materials. Analysis of spectroscopic data from laboratory, aircraft, and spacecraft instrumentation requires a knowledge base. The spectral library discussed here forms a knowledge base for the spectroscopy of minerals and related materials of importance to a variety of research programs being conducted at the U.S. Geological Survey. Much of this library grew out of the need for spectra to support imaging spectroscopy studies of the Earth and planets. Imaging spectrometers, such as the National Aeronautics and Space Administration (NASA) Airborne Visible/Infra Red Imaging Spectrometer (AVIRIS) or the NASA Cassini Visual and Infrared Mapping Spectrometer (VIMS) which is currently orbiting Saturn, have narrow bandwidths in many contiguous spectral channels that permit accurate definition of absorption features in spectra from a variety of materials. Identification of materials from such data requires a comprehensive spectral library of minerals, vegetation, man-made materials, and other subjects in the scene. Our research involves the use of the spectral library to identify the components in a spectrum of an unknown. Therefore, the quality of the library must be very good. However, the quality required in a spectral library to successfully perform an investigation depends on the scientific questions to be answered and the type of algorithms to be used. For example, to map a mineral using imaging spectroscopy and the mapping algorithm of Clark and others (1990a, 2003b

A spectral reflectance study (0.4-2.5 μm) of selected playa evaporite mineral deposits and related geochemical processes

USGS Publications Warehouse

Crowley, James K.

1990-01-01

Playa evaporite mineral deposits show major compositional variations related to differences in lithology, hydrology, and groundwater geochemistry. The use of visible and near-infrared (VNIR) spectral reflectance measurements as a technique for investigating the mineralogy of playa efflorescent crusts is examined. Samples of efflorescent crust were collected from 4 playa: Bristol Dry Lake, Saline Valley, Teels Marsh, and Rhodes Marsh--all located in eastern California and western Nevada. Laboratory and field spectral analyses coupled with X-ray diffraction analyses of the crusts yielded the following observations: VNIR spectra of unweathered salt crusts can be used to infer the general chemistry of near-surface brines; VNIR spectra are very sensitive for detecting minor hydrate mineral phases contained in mixtures with anhydrous, spectrally featureless, minerals such as halite (NaCl) and thernardite (Na2So4); borate minerals exhibit particularly strong VNIR spectral features that permit small amounts of borate to be detected in efflorescent salt crusts; remote sensing spectral measurements of playa efflorescent crusts may have applications in global studies of playa brines and minerals.

Characterizing Quasar Outflows I: Sample, Spectral Measurements

NASA Astrophysics Data System (ADS)

Ganguly, Rajib; Christenson, D. H.; Richmond, J. M.; Derseweh, J. A.; Robbins, J. M.; Townsend, S. L.; Stark, M. A.

2012-05-01

Galaxy evolution models have shown that quasars are a crucial ingredient in the evolution of massive galaxies. Outflows play a key role in the story of quasars and their host galaxies, by helping regulate the accretion process, the star-formation rate and mass of the host galaxy (i.e., feedback). The prescription for modeling outflows as a contributor to feedback requires knowledge of the outflow velocity, geometry, and column density. In particular, we need to understand how these depend on physical parameters and how much is determined stochastically (and with what distribution). For this purpose, we are examining a sample of 11000 z=1.7-2.0 quasars from the Sloan Digital Sky Survey. This redshift range permits the following from the SDSS spectra: (1) separation of objects that do and do not exhibit outflows; (2) classification/measurement of outflow properties (ionization, velocity, velocity width); and (3) measurements of UV emission line and continuum parameters. In this poster, we subjectively divide these quasars into four categories: broad absorption-line quasars (2700 objects), associated absorption-line quasars (1700 objects), reddened quasars (160 objects), and unabsorbed/unreddened quasars (6300 objects). We present measurements of the absorption (velocities, velocity widths, equivalent widths), composite spectral profiles of outflows as a function of velocity, as well as measurements of the continuum and CIV, MgII, and FeII emission-line properties. In accompanying posters, we add photometry from the rest-frame X-ray (ROSAT and Chandra), EUV (GALEX), optical (2MASS), and infrared (WISE) bands to complete the SED. The continuum and emission-line measurements from the SDSS spectra and accompanying photometry provides estimates on the black hole masses, bolometric luminsosities, and SED. We consider empirically how these affect the outflow properties. This material is based upon work supported by the National Aeronautics and Space Administration under

Characterization of spectral and intensity changes with measurement geometry in various light guides used in scintillation dosimetry.

PubMed

Simiele, Eric A; DeWerd, Larry A

2018-05-24

To characterize response changes of various light guides used in megavoltage (MV) photon beam scintillation dosimetry as a function of irradiation conditions. Particular emphasis was placed on quantifying the impact of response changes on the Čerenkov light ratio (CLR). Intensity and spectral response measurements as a function of dose, depth, and fiber-beam angle were performed with a commercial scintillation detector stripped of its scintillation material and five different custom-made light guides. The core materials of the light guides investigated consisted of polymethyl methacrylate (PMMA), low- and high-hydroxyl content silica, and polystyrene. Dose levels ranging from 50 monitor units (MU) to 1000 MU, depths ranging from 1 to 20 cm, and fiber-beam angles ranging from 10° to 90° were investigated. All measurements were performed at a photon beam energy of 6 MV. The CLR was calculated by taking the ratio of the responses in the blue to green spectral regions. There was no significant change in the CLR measured with the modified commercial scintillation detector as a function of delivered dose. In addition, increases in the CLR as functions of depth and fiber-beam angle were observed where the maximum changes were 4.2% and 3.6%, respectively. The spectrum measurements showed no observable changes in spectral shape with depth except for the low-hydroxyl content silica fiber. Variations in the measured spectral shape with fiber-beam angle were observed for all fibers investigated. The magnitude of the changes in the spectral shape varied with fiber type, where the silica fibers exhibited the largest changes and the plastic fibers exhibited the smallest changes. Increases in the CLR were observed for the silica fibers with depth and for all fibers with fiber-beam angle. The plastic fibers showed no significant change in the CLR as a function of depth. Increases of 3.1% and 9.5% in the CLR were observed for the high- and low-hydroxyl content silica fibers

Spectral characterization of dielectric materials using terahertz measurement systems

NASA Astrophysics Data System (ADS)

Seligman, Jeffrey M.

The performance of modern high frequency components and electronic systems are often limited by the properties of the materials from which they are made. Over the past decade, there has been an increased emphasis on the development of new, high performance dielectrics for use in high frequency systems. The development of these materials requires novel broadband characterization, instrumentation, and extraction techniques, from which models can be formulated. For this project several types of dielectric sheets were characterized at terahertz (THz) frequencies using quasi-optical (free-space) techniques. These measurement systems included a Fourier Transform Spectrometer (FTS, scalar), a Time Domain Spectrometer (TDS, vector), a Scalar Network Analyzer (SNA), and a THz Vector Network Analyzer (VNA). Using these instruments the THz spectral characteristics of dielectric samples were obtained. Polarization based anisotropy was observed in many of the materials measured using vector systems. The TDS was the most informative and flexible instrument for dielectric characterization at THz frequencies. To our knowledge, this is the first such comprehensive study to be performed. Anisotropy effects within materials that do not come into play at microwave frequencies (e.g. ~10 GHz) were found, in many cases, to increase measured losses at THz frequencies by up to an order of magnitude. The frequency dependent properties obtained during the course of this study included loss tangent, permittivity (index of refraction), and dielectric constant. The results were largely consistent between all the different systems and correlated closely to manufacturer specifications over a wide frequency range (325 GHz-1.5 THz). Anisotropic behavior was observed for some of the materials. Non-destructive evaluation and testing (NDE/NDT) techniques were used throughout. A precision test fixture was developed to accomplish these measurements. Time delay, insertion loss, and S-parameters were

Leaf Phenology of Amazonian Canopy Trees as Revealed by Spectral and Physiochemical Measurements

NASA Astrophysics Data System (ADS)

Chavana-Bryant, C.; Gerard, F. F.; Malhi, Y.; Enquist, B. J.; Asner, G. P.

2013-12-01

The phenological dynamics of terrestrial ecosystems reflect the response of the Earth's biosphere to inter- and intra-annual dynamics of climatic and hydrological regimes. Some Dynamic Global Vegetation Models (GDVMs) have predicted that by 2050 the Amazon rainforest will begin to dieback (Cox et al. 2000, Nature) or that the ecosystem will become unsustainable (Salazar et al. 2007, GRL). One major component in DGVMs is the simulation of vegetation phenology, however, modelers are challenged with the estimation of tropical phenology which is highly complex. Current modeled phenology is based on observations of temperate vegetation and accurate representation of tropical phenology is long overdue. Remote sensing (RS) data are a key tool in monitoring vegetation dynamics at regional and global scales. Of the many RS techniques available, time-series analysis of vegetation indices (VIs) has become the most common approach in monitoring vegetation phenology (Samanta et al. 2010, GRL; Bradley et al. 2011, GCB). Our research focuses on investigating the influence that age related variation in the spectral reflectance and physiochemical properties of leaves may have on VIs of tropical canopies. In order to do this, we collected a unique leaf and canopy phenological dataset at two different Amazonian sites: Inselberg, French Guyana (FG) and Tambopata, Peru (PE). Hyperspectral reflectance measurements were collected from 4,102 individual leaves sampled to represent different leaf ages and vertical canopy positions (top, mid and low canopy) from 20 different canopy tree species (8 in FG and 12 in PE). These leaf spectra were complemented with 1) leaf physical measurements: fresh and dry weight, area and thickness, LMA and LWC and 2) leaf chemical measurements: %N, %C, %P, C:N and d13C. Canopy level observations included top-of-canopy reflectance measurements obtained using a multispectral 16-band radiometer, leaf demography (tot. number and age distribution) and branch

Spectral identification and quantification of salts in the Atacama Desert

NASA Astrophysics Data System (ADS)

Harris, J. K.; Cousins, C. R.; Claire, M. W.

2016-10-01

Salt minerals are an important natural resource. The ability to quickly and remotely identify and quantify salt deposits and salt contaminated soils and sands is therefore a priority goal for the various industries and agencies that utilise salts. The advent of global hyperspectral imagery from instruments such as Hyperion on NASA's Earth-Observing 1 satellite has opened up a new source of data that can potentially be used for just this task. This study aims to assess the ability of Visible and Near Infrared (VNIR) spectroscopy to identify and quantify salt minerals through the use of spectral mixture analysis. The surface and near-surface soils of the Atacama Desert in Chile contain a variety of well-studied salts, which together with low cloud coverage, and high aridity, makes this region an ideal testbed for this technique. Two forms of spectral data ranging 0.35 - 2.5 μm were collected: laboratory spectra acquired using an ASD FieldSpec Pro instrument on samples from four locations in the Atacama desert known to have surface concentrations of sulfates, nitrates, chlorides and perchlorates; and images from the EO-1 satellite's Hyperion instrument taken over the same four locations. Mineral identifications and abundances were confirmed using quantitative XRD of the physical samples. Spectral endmembers were extracted from within the laboratory and Hyperion spectral datasets and together with additional spectral library endmembers fed into a linear mixture model. The resulting identification and abundances from both dataset types were verified against the sample XRD values. Issues of spectral scale, SNR and how different mineral spectra interact are considered, and the utility of VNIR spectroscopy and Hyperion in particular for mapping specific salt concentrations in desert environments is established. Overall, SMA was successful at estimating abundances of sulfate minerals, particularly calcium sulfate, from both hyperspectral image and laboratory sample spectra

High Spectral Resolution Lidar Measurements Using an I2 Absorption Filter

NASA Technical Reports Server (NTRS)

Eloranta, E. W.; Piironen, P.

1996-01-01

The University of Wisconsin high spectral resolution lidar (HSRL) measures optical properties of the atmosphere by separating the Doppler-broadened molecular backscatter return from the unbroadened aerosol return. The HSRL was modified to use an I2 absorption cell The modified HSRL transmitter uses a continuously pumped, Q-switched, injection seeded, frequency doubled Nd:YAG laser operating at a 4 kHz pulse repetition rate. This laser is tunable over a 124 GHz frequency range by temperature tuning the seed laser under computer control.

Spectral dilation of L(B,H)-valued measures and its application to stationary dilation for Banach space valued processes

NASA Technical Reports Server (NTRS)

Miamee, A. G.

1988-01-01

Let B be a Banach space and H and K two Hilbert spaces. The spectral dilation of L(B,H)-valued measures is studied and it is shown that the recent results of Makagon and Salehi (1986) and Rosenberg (1982) on the dilation of L(K,H)-valued measures can be extended to hold for the general Banach space setting of L(B,H)-valued measures. These L(B,H)-valued measures are closely connected to the Banach space valued processes. This connection is recalled and as application of spectral dilation of L(B,H)-valued measures the well known stationary dilation results for scalar valued processes is extended to the case of Banach space valued processes.

Application of a two-stream radiative transfer model for leaf lignin and cellulose concentrations from spectral reflectance measurements, part 2

NASA Technical Reports Server (NTRS)

Conel, James E.; Vandenbosch, Jeannette; Grove, Cindy I.

1993-01-01

We used the Kubelka-Munk theory of diffuse spectral reflectance in layers to analyze influences of multiple chemical components in leaves. As opposed to empirical approaches to estimation of plant chemistry, the full spectral resolution of laboratory reflectance data was retained in an attempt to estimate lignin or other constituent concentrations from spectral band positions. A leaf water reflectance spectrum was derived from theoretical mixing rules, reflectance observations, and calculations from theory of intrinsic k- and s-functions. Residual reflectance bands were then isolated from spectra of fresh green leaves. These proved hard to interpret for composition in terms of simple two component mixtures such as lignin and cellulose. We next investigated spectral and dilution influences of other possible components (starch, protein). These components, among others, added to cellulose in hypothetical mixtures, produce band displacements similar to lignin, but will disguise by dilution the actual abundance of lignin present in a multicomponent system. This renders interpretation of band positions problematical. Knowledge of end-members and their spectra, and a more elaborate mixture analysis procedure may be called for. Good observational atmospheric and instrumental conditions and knowledge thereof are required for retrieval of expected subtle reflectance variations present in spectra of green vegetation.

Latitudinal variation of speed and mass flux in the acceleration region of the solar wind inferred from spectral broadening measurements

NASA Technical Reports Server (NTRS)

Woo, Richard; Goldstein, Richard M.

1994-01-01

Spectral broadening measurements conducted at S-band (13-cm wavelength) during solar minimum conditions in the heliocentric distance range of 3-8 R(sub O) by Mariner 4, Pioneer 10, Mariner 10, Helios 1, Helios 2, and Viking have been combined to reveal a factor of 2.6 reduction in bandwidth from equator to pole. Since spectral broadening bandwidth depends on electron density fluctuation and solar wind speed, and latitudinal variation of the former is available from coherence bandwidth measurements, the remote sensing spectral broadening measurements provide the first determination of the latitudinal variation of solar wind speed in the acceleration region. When combined with electron density measurements deduced from white-light coronagraphs, this result also leads to the first determination of the latitudinal variation of mass flux in the acceleration region. From equator to pole, solar wind speed increases by a factor of 2.2, while mass flux decreases by a factor of 2.3. These results are consistent with measurements of solar wind speed by multi-station intensity scintillation measurements, as well as measurements of mass flux inferred from Lyman alpha observations, both of which pertain to the solar wind beyond 0.5 AU. The spectral broadening observations, therefore, strengthen earlier conclusions about the latitudinal variation of solar wind speed and mass flux, and reinforce current solar coronal models and their implications for solar wind acceleration and solar wind modeling.

(LMRG): Microscope Resolution, Objective Quality, Spectral Accuracy and Spectral Un-mixing

PubMed Central

Bayles, Carol J.; Cole, Richard W.; Eason, Brady; Girard, Anne-Marie; Jinadasa, Tushare; Martin, Karen; McNamara, George; Opansky, Cynthia; Schulz, Katherine; Thibault, Marc; Brown, Claire M.

2012-01-01

The second study by the LMRG focuses on measuring confocal laser scanning microscope (CLSM) resolution, objective lens quality, spectral imaging accuracy and spectral un-mixing. Affordable test samples for each aspect of the study were designed, prepared and sent to 116 labs from 23 countries across the globe. Detailed protocols were designed for the three tests and customized for most of the major confocal instruments being used by the study participants. One protocol developed for measuring resolution and objective quality was recently published in Nature Protocols (Cole, R. W., T. Jinadasa, et al. (2011). Nature Protocols 6(12): 1929–1941). The first study involved 3D imaging of sub-resolution fluorescent microspheres to determine the microscope point spread function. Results of the resolution studies as well as point spread function quality (i.e. objective lens quality) from 140 different objective lenses will be presented. The second study of spectral accuracy looked at the reflection of the laser excitation lines into the spectral detection in order to determine the accuracy of these systems to report back the accurate laser emission wavelengths. Results will be presented from 42 different spectral confocal systems. Finally, samples with double orange beads (orange core and orange coating) were imaged spectrally and the imaging software was used to un-mix fluorescence signals from the two orange dyes. Results from 26 different confocal systems will be summarized. Time will be left to discuss possibilities for the next LMRG study.

Performance testing of radiobioassay laboratories: In vivo measurements, Final Report

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

MacLellan, J.A.; Traub, R.J.; Olsen, P.C.

1990-04-01

A study of two rounds of in vivo laboratory performance testing was undertaken by Pacific Northwest Laboratory (PNL) to determine the appropriateness of the in vivo performance criteria of draft American National Standards Institute (ANSI) standard ANSI N13.3, Performance Criteria for Bioassay.'' The draft standard provides guidance to in vivo counting facilities regarding the sensitivity, precision, and accuracy of measurements for certain categories of commonly assayed radionuclides and critical regions of the body. This report concludes the testing program by presenting the results of the Round Two testing. Testing involved two types of measurements: chest counting for radionuclide detection inmore » the lung, and whole body counting for detection of uniformly distributed material. Each type of measurement was further divided into radionuclide categories as defined in the draft standard. The appropriateness of the draft standard criteria by measuring a laboratory's ability to attain them were judged by the results of both round One and Round Two testing. The testing determined that performance criteria are set at attainable levels, and the majority of in vivo monitoring facilities passed the criteria when complete results were submitted. 18 refs., 18 figs., 15 tabs.« less

Gas temperature and density measurements based on spectrally resolved Rayleigh-Brillouin scattering

NASA Technical Reports Server (NTRS)

Seasholtz, Richard G.; Lock, James A.

1992-01-01

The use of molecular Rayleigh scattering for measurements of gas density and temperature is evaluated. The technique used is based on the measurement of the spectrum of the scattered light, where both temperature and density are determined from the spectral shape. Planar imaging of Rayleigh scattering from air using a laser light sheet is evaluated for ambient conditions. The Cramer-Rao lower bounds for the shot-noise limited density and temperature measurement uncertainties are calculated for an ideal optical spectrum analyzer and for a planar mirror Fabry-Perot interferometer used in a static, imaging mode. With this technique, a single image of the Rayleigh scattered light can be analyzed to obtain density (or pressure) and temperature. Experimental results are presented for planar measurements taken in a heated air stream.

[Development of human blood glucose noninvasive measurement system based on near infrared spectral technology].

PubMed

Li, Qing-bo; Liu, Jie-qiang; Li, Xiang

2012-03-01

A small non-invasive measurement system for human blood glucose has been developed, which can achieve fast, real-time and non invasive measurement of human blood glucose. The device is mainly composed of four parts, i. e. fixture, light system, data acquisition and processing systems, and spectrometer. A new scheme of light source driving was proposed, which can meet the requirements of light source under a variety of conditions of spectral acquisition. An integrated fixture design was proposed, which not only simplifies the optical structure of the system, but also improves the reproducibility of measurement conditions. The micro control system mainly achieves control function, dealing with data, data storage and so on. As the most important component, microprocessor DSP TMS320F2812 has many advantages, such as low power, high processing speed, high computing ability and so on. Wavelet denoising is used to pretreat the spectral data, which can decrease the loss of incident light and improve the signal-to-noise ratio. Kernel partial least squares method was adopted to build the mathematical model, which can improve the precision of the system. In the calibration experiment of the system, the standard values were measured by One-Touch. The correlation coefficient between standard blood glucose values and truth values is 0.95. The root mean square error of measurement is 0.6 mmol x L(-1). The system has good reproducibility.

Spectral stratigraphy

NASA Technical Reports Server (NTRS)

Lang, Harold R.

1991-01-01

A new approach to stratigraphic analysis is described which uses photogeologic and spectral interpretation of multispectral remote sensing data combined with topographic information to determine the attitude, thickness, and lithology of strata exposed at the surface. The new stratigraphic procedure is illustrated by examples in the literature. The published results demonstrate the potential of spectral stratigraphy for mapping strata, determining dip and strike, measuring and correlating stratigraphic sequences, defining lithofacies, mapping biofacies, and interpreting geological structures.

Laboratory Exercises to Teach Clinically Relevant Chemistry of Antibiotics

PubMed Central

Chelette, Candace T.

2014-01-01

Objectives. To design, implement, and evaluate student performance on clinically relevant chemical and spectral laboratory exercises on antibiotics. Design. In the first of 2 exercises, second-year pharmacy students enrolled in an integrated laboratory sequence course studied the aqueous stability of ß-lactam antibiotics using a spectral visual approach. In a second exercise, students studied the tendency of tetracycline, rifamycins, and fluoroquinolones to form insoluble chelate complexes (turbidity) with polyvalent metals. Assessment. On a survey to assess achievement of class learning objectives, students agreed the laboratory activities helped them better retain important information concerning antibiotic stability and interactions. A significant improvement was observed in performance on examination questions related to the laboratory topics for 2012 and 2013 students compared to 2011 students who did not complete the laboratory. A 1-year follow-up examination question administered in a separate course showed >75% of the students were able to identify rifamycins-food interactions compared with <25% of students who had not completed the laboratory exercises. Conclusion. The use of spectral visual approaches allowed students to investigate antibiotic stability and interactions, thus reinforcing the clinical relevance of medicinal chemistry. Students’ performance on questions at the 1-year follow-up suggested increased retention of the concepts learned as a result of completing the exercises. PMID:24672070

Laboratory exercises to teach clinically relevant chemistry of antibiotics.

PubMed

El Sayed, Khalid A; Chelette, Candace T

2014-03-12

To design, implement, and evaluate student performance on clinically relevant chemical and spectral laboratory exercises on antibiotics. In the first of 2 exercises, second-year pharmacy students enrolled in an integrated laboratory sequence course studied the aqueous stability of ß-lactam antibiotics using a spectral visual approach. In a second exercise, students studied the tendency of tetracycline, rifamycins, and fluoroquinolones to form insoluble chelate complexes (turbidity) with polyvalent metals. On a survey to assess achievement of class learning objectives, students agreed the laboratory activities helped them better retain important information concerning antibiotic stability and interactions. A significant improvement was observed in performance on examination questions related to the laboratory topics for 2012 and 2013 students compared to 2011 students who did not complete the laboratory. A 1-year follow-up examination question administered in a separate course showed >75% of the students were able to identify rifamycins-food interactions compared with <25% of students who had not completed the laboratory exercises. The use of spectral visual approaches allowed students to investigate antibiotic stability and interactions, thus reinforcing the clinical relevance of medicinal chemistry. Students' performance on questions at the 1-year follow-up suggested increased retention of the concepts learned as a result of completing the exercises.

The development of a modified spectral ripple test.

PubMed

Aronoff, Justin M; Landsberger, David M

2013-08-01

Poor spectral resolution can be a limiting factor for hearing impaired listeners, particularly for complex listening tasks such as speech understanding in noise. Spectral ripple tests are commonly used to measure spectral resolution, but these tests contain a number of potential confounds that can make interpretation of the results difficult. To measure spectral resolution while avoiding those confounds, a modified spectral ripple test with dynamically changing ripples was created, referred to as the spectral-temporally modulated ripple test (SMRT). This paper describes the SMRT and provides evidence that it is sensitive to changes in spectral resolution.

Geometric optimisation of an accurate cosine correcting optic fibre coupler for solar spectral measurement.

PubMed

Cahuantzi, Roberto; Buckley, Alastair

2017-09-01

Making accurate and reliable measurements of solar irradiance is important for understanding performance in the photovoltaic energy sector. In this paper, we present design details and performance of a number of fibre optic couplers for use in irradiance measurement systems employing remote light sensors applicable for either spectrally resolved or broadband measurement. The angular and spectral characteristics of different coupler designs are characterised and compared with existing state-of-the-art commercial technology. The new coupler designs are fabricated from polytetrafluorethylene (PTFE) rods and operate through forward scattering of incident sunlight on the front surfaces of the structure into an optic fibre located in a cavity to the rear of the structure. The PTFE couplers exhibit up to 4.8% variation in scattered transmission intensity between 425 nm and 700 nm and show minimal specular reflection, making the designs accurate and reliable over the visible region. Through careful geometric optimization near perfect cosine dependence on the angular response of the coupler can be achieved. The PTFE designs represent a significant improvement over the state of the art with less than 0.01% error compared with ideal cosine response for angles of incidence up to 50°.

Validation of a clinical assessment of spectral-ripple resolution for cochlear implant users.

PubMed

Drennan, Ward R; Anderson, Elizabeth S; Won, Jong Ho; Rubinstein, Jay T

2014-01-01

Nonspeech psychophysical tests of spectral resolution, such as the spectral-ripple discrimination task, have been shown to correlate with speech-recognition performance in cochlear implant (CI) users. However, these tests are best suited for use in the research laboratory setting and are impractical for clinical use. A test of spectral resolution that is quicker and could more easily be implemented in the clinical setting has been developed. The objectives of this study were (1) To determine whether this new clinical ripple test would yield individual results equivalent to the longer, adaptive version of the ripple-discrimination test; (2) To evaluate test-retest reliability for the clinical ripple measure; and (3) To examine the relationship between clinical ripple performance and monosyllabic word recognition in quiet for a group of CI listeners. Twenty-eight CI recipients participated in the study. Each subject was tested on both the adaptive and the clinical versions of spectral ripple discrimination, as well as consonant-nucleus-consonant word recognition in quiet. The adaptive version of spectral ripple used a two-up, one-down procedure for determining spectral ripple discrimination threshold. The clinical ripple test used a method of constant stimuli, with trials for each of 12 fixed ripple densities occurring six times in random order. Results from the clinical ripple test (proportion correct) were then compared with ripple-discrimination thresholds (in ripples per octave) from the adaptive test. The clinical ripple test showed strong concurrent validity, evidenced by a good correlation between clinical ripple and adaptive ripple results (r = 0.79), as well as a correlation with word recognition (r = 0.7). Excellent test-retest reliability was also demonstrated with a high test-retest correlation (r = 0.9). The clinical ripple test is a reliable nonlinguistic measure of spectral resolution, optimized for use with CI users in a clinical setting. The test

The Evolving Role of Field and Laboratory Seismic Measurements in Geotechnical Engineering

NASA Astrophysics Data System (ADS)

Stokoe, K. H.

2017-12-01

The geotechnical engineering has been faced with the problem of characterizing geological materials for site-specific design in the built environment since the profession began. When one of the design requirements included determining the dynamic response of important and critical facilities to earthquake shaking or other types of dynamic loads, seismically-based measurements in the field and laboratory became important tools for direct characterization of the stiffnesses and energy dissipation (material damping) of these materials. In the 1960s, field seismic measurements using small-strain body waves were adapted from exploration geophysics. At the same time, laboratory measurements began using dynamic, torsional, resonant-column devices to measure shear stiffness and material damping in shear. The laboratory measurements also allowed parameters such as material type, confinement state, and nonlinear straining to be evaluated. Today, seismic measurements are widely used and evolving because: (1) the measurements have a strong theoretical basis, (2) they can be performed in the field and laboratory, thus forming an important link between these measurements, and (3) in recent developments in field testing involving surface waves, they are noninvasive which makes them cost effective in comparison to other methods. Active field seismic measurements are used today over depths ranging from about 5 to 1000 m. Examples of shear-wave velocity (VS) profiles evaluated using boreholes, penetrometers, suspension logging, and Rayleigh-type surface waves are presented. The VS measurements were performed in materials ranging from uncemented soil to unweathered rock. The coefficients of variation (COVs) in the VS profiles are generally less than 0.15 over sites with surface areas of 50 km2 or more as long as material types are not laterally mixed. Interestingly, the largest COVs often occur around layer boundaries which vary vertically. It is also interesting to observe how the

Impact of Biology Laboratory Courses on Students' Science Performance and Views about Laboratory Courses in General: Innovative Measurements and Analyses

ERIC Educational Resources Information Center

Lee, Silvia Wen-Yu; Lai, Yung-Chih; Yu, Hon-Tsen Alex; Lin, Yu-Teh Kirk

2012-01-01

Despite the fact that some educational researchers believe that laboratory courses promote outcomes in cognitive and affective domains in science learning, others have argued that laboratory courses are costly in relation to their value. Moreover, effective measurement of student learning in the laboratory is an area requiring further…

Laboratory Data for X-Ray Astronomy

NASA Technical Reports Server (NTRS)

Beiersdorfer, P.; Brown, G. V.; Chen, H.; Gu, M.-F.; Kahn, S. M.; Lepson, J. K.; Savin, D. W.; Utter, S. B.

2000-01-01

Laboratory facilities have made great strides in producing large sets of reliable data for X-ray astronomy, which include ionization and recombination cross sections needed for charge balance calculations as well as the atomic data needed for interpreting X-ray line formation. We discuss data from the new generation sources and pay special attention to the LLNL electron beam ion trap experiment, which is unique in its ability to provide direct laboratory access to spectral data under precisely controlled conditions that simulate those found in many astrophysical plasmas. Examples of spectral data obtained in the 1-160 A wavelength range are given illustrating the type of laboratory X-ray data produced in support of such missions as Chandra, X-Ray Multi-Mirror telescope (XMM), Advanced Satellite for Cosmology and Astrophysics (ASCA) and Extreme Ultraviolet Explorer Satellite (EUVE).

Inter-laboratory comparison study on measuring semi-volatile organic chemicals in standards and air samples.

PubMed

Su, Yushan; Hung, Hayley

2010-11-01

Measurements of semi-volatile organic chemicals (SVOCs) were compared among 21 laboratories from 7 countries through the analysis of standards, a blind sample, an air extract, and an atmospheric dust sample. Measurement accuracy strongly depended on analytes, laboratories, and types of standards and samples. Intra-laboratory precision was generally good with relative standard deviations (RSDs) of triplicate injections <10% and with median differences of duplicate samples between 2.1 and 22%. Inter-laboratory variability, measured by RSDs of all measurements, was in the range of 2.8-58% in analyzing standards, and 6.9-190% in analyzing blind sample and air extract. Inter-laboratory precision was poorer when samples were subject to cleanup processes, or when SVOCs were quantified at low concentrations. In general, inter-laboratory differences up to a factor of 2 can be expected to analyze atmospheric SVOCs. When comparing air measurements from different laboratories, caution should be exercised if the data variability is less than the inter-laboratory differences. 2010. Published by Elsevier Ltd. All rights reserved.

Investigation of specification measures for the Software Engineering Laboratory (SEL)

NASA Technical Reports Server (NTRS)

1984-01-01

Requirements specification measures are investigated for potential application in the Software Engineering Laboratory. Eighty-seven candidate measures are defined; sixteen are recommended for use. Most measures are derived from a new representation, the Composite Specification Model, which is introduced. The results of extracting the specification measures from the requirements of a real system are described.

Spectral induced polarization (SIP) measurement of NAPL contaminated soils

NASA Astrophysics Data System (ADS)

Schwartz, N.; Huisman, J. A.; Furman, A.

2010-12-01

The potential applicability of spectral induce polarization (SIP) as a tool to map NAPLs (non aqueous phase liquids) contaminants at the subsurface lead researchers to investigate the electric signature of those contaminant on the spectral response. However, and despite the cumulative efforts, the effect of NAPL on the electrical properties of soil, and the mechanisms that control this effect are largely unknown. In this work a novel experiment is designed to further examine the effect of NAPL on the electrical properties of partially saturated soil. The measurement system that used is the ZEL-SIP04 impedance meter developed at the Forschungszentrum Julich, Germany. The system accurately (nominal phase precision of 0.1 mrad below 1 kHz) measures the phase and the amplitude of a material possessing a very low polarization (such as soil). The sample holder has a dimension of 60 cm long and 4.6 cm in diameter. Current and potential electrodes were made of brass, and while the current electrodes were inserted in full into the soil, the contact between the potential electrode and the soil was made through an Agarose bridge. Two types of soils were used: clean quartz sand, and a mixture of sand with clean Bentonite. Each soil (sandy or clayey) was mixed with water to get saturation degree of 30%. Following the mixture with water, NAPL was added and the composite were mixed again. Packing was done by adding and compressing small portions of the soil to the column. A triplicate of each mixture was made with a good reproducible bulk density. Both for the sandy and clayey soils, the results indicate that additions of NAPL decrease the real part of the complex resistivity. Additionally, for the sandy soil this process is time depended, and that a further decrease in resistivity develops over time. The results are analyzed considering geometrical factors: while the NAPL is electrically insulator, addition of NAPL to the soil is expected to increase the connectivity of the

Innovative Mobile Smart Photonic Dimensional, Color and Spectral Measurement Engineering

NASA Astrophysics Data System (ADS)

Hofmann, Dr Dietrich, Prof; Dittrich (B. Eng. , Paul-Gerald; Höfner (B. Eng. , Dieter; Kraus, Daniel

2015-02-01

Aim of the paper is the demonstration of a paradigm shift in dimensional, color and spectral measurements in industry, biology/medicine, farming/environmental protection and security, as well as in education and training: Measurement engineering and quality assurance become mobile, modular and smart. Smartpads, smartphones and smartwatches (smartcomps) in combination with innovative hardware apps (hwapps) and conventional software apps (swapps) are fundamental enablers for the transformation from conventional stationary working places towards innovative mobile working places with in-field measurements and point-of-care (POC) diagnostics. Furthermore mobile open online courses (MOOCs) are transforming the study habits. Practical examples for the application of innovative photonic micro dimensiometers, colorimeters and spectrometers will be given. The innovative approach opens so far untapped enormous markets for measurement science, engineering, applications, education and training. These innovative working conditions will be fast accepted due to their convenience, reliability and affordability. A highly visible advantage of smartcomps is the huge number of their real distribution, their worldwide connectivity via Internet and cloud services, the standardized interfaces like USB and HDMI and the experienced capabilities of their users for practical operations, obtained with their private smartcomps.

Spectral correction algorithm for multispectral CdTe x-ray detectors

NASA Astrophysics Data System (ADS)

Christensen, Erik D.; Kehres, Jan; Gu, Yun; Feidenhans'l, Robert; Olsen, Ulrik L.

2017-09-01

Compared to the dual energy scintillator detectors widely used today, pixelated multispectral X-ray detectors show the potential to improve material identification in various radiography and tomography applications used for industrial and security purposes. However, detector effects, such as charge sharing and photon pileup, distort the measured spectra in high flux pixelated multispectral detectors. These effects significantly reduce the detectors' capabilities to be used for material identification, which requires accurate spectral measurements. We have developed a semi analytical computational algorithm for multispectral CdTe X-ray detectors which corrects the measured spectra for severe spectral distortions caused by the detector. The algorithm is developed for the Multix ME100 CdTe X-ray detector, but could potentially be adapted for any pixelated multispectral CdTe detector. The calibration of the algorithm is based on simple attenuation measurements of commercially available materials using standard laboratory sources, making the algorithm applicable in any X-ray setup. The validation of the algorithm has been done using experimental data acquired with both standard lab equipment and synchrotron radiation. The experiments show that the algorithm is fast, reliable even at X-ray flux up to 5 Mph/s/mm2, and greatly improves the accuracy of the measured X-ray spectra, making the algorithm very useful for both security and industrial applications where multispectral detectors are used.

Atmospheric correction for JPSS-2 VIIRS response versus scan angle measurements

NASA Astrophysics Data System (ADS)

McIntire, Jeffrey; Moeller, Chris; Oudrari, Hassan; Xiong, Xiaoxiong

2017-09-01

The Joint Polar Satellite System 2 (JPSS-2) Visible Infrared Imaging Radiometer Suite (VIIRS) includes one spectral band centered in a strong atmospheric absorption region. As much of the pre-launch calibration is performed under laboratory ambient conditions, accurately accounting for the absorption, and thereby ensuring the transfer of the sensor calibration to on-orbit operations, is necessary to generate science quality data products. This work is focused on the response versus scan angle (RVS) measurements, which characterize the relative scan angle dependent reflectance of the JPSS-2 VIIRS instrument optics. The spectral band of interest, centered around 1378 nm, is within a spectral region strongly effected by water vapor absorption. The methodology used to model the absolute humidity and the atmospheric transmittance under the laboratory conditions is detailed. The application of this transmittance to the RVS determination is then described including an uncertainty estimate; a comparison to the pre-launch measurements from earlier sensor builds is also performed.

Spectral-domain low-coherence interferometry for phase-sensitive measurement of Faraday rotation at multiple depths.

PubMed

Yeh, Yi-Jou; Black, Adam J; Akkin, Taner

2013-10-10

We describe a method for differential phase measurement of Faraday rotation from multiple depth locations simultaneously. A polarization-maintaining fiber-based spectral-domain interferometer that utilizes a low-coherent light source and a single camera is developed. Light decorrelated by the orthogonal channels of the fiber is launched on a sample as two oppositely polarized circular states. These states reflect from sample surfaces and interfere with the corresponding states of the reference arm. A custom spectrometer, which is designed to simplify camera alignment, separates the orthogonal channels and records the interference-related oscillations on both spectra. Inverse Fourier transform of the spectral oscillations in k-space yields complex depth profiles, whose amplitudes and phase difference are related to reflectivity and Faraday rotation within the sample, respectively. Information along a full depth profile is produced at the camera speed without performing an axial scan for a multisurface sample. System sensitivity for the Faraday rotation measurement is 0.86 min of arc. Verdet constants of clear liquids and turbid media are measured at 687 nm.

Spectral characterization of natural backgrounds

NASA Astrophysics Data System (ADS)

Winkelmann, Max

2017-10-01

As the distribution and use of hyperspectral sensors is constantly increasing, the exploitation of spectral features is a threat for camouflaged objects. To improve camouflage materials at first the spectral behavior of backgrounds has to be known to adjust and optimize the spectral reflectance of camouflage materials. In an international effort, the NATO CSO working group SCI-295 "Development of Methods for Measurements and Evaluation of Natural Background EO Signatures" is developing a method how this characterization of backgrounds has to be done. It is obvious that the spectral characterization of a background will be quite an effort. To compare and exchange data internationally the measurements will have to be done in a similar way. To test and further improve this method an international field trial has been performed in Storkow, Germany. In the following we present first impressions and lessons learned from this field campaign and describe the data that has been measured.

The NASA MSFC Electrostatic Levitation (ESL) Laboratory: Summary of Capabilities, Recent Upgrades, and Future Work

NASA Technical Reports Server (NTRS)

SanSoucie, Michael P.; Vermilion, David J.; Rogers, Jan R.

2015-01-01

The NASA Marshall Space Flight Center (MSFC) electrostatic levitation (ESL) laboratory has a long history of providing materials research and thermophysical property data. A summary of the labs capabilities, recent upgrades, and ongoing and future work will be provided. The laboratory has recently added two new capabilities to its main levitation chamber: a rapid quench system and an oxygen control system. The rapid quench system allows samples to be dropped into a quench vessel that can be filled with a low melting point material, such as a gallium or indium alloy. Thereby allowing rapid quenching of undercooled liquid metals. The oxygen control system consists of an oxygen sensor, oxygen pump, and a control unit. The sensor is a potentiometric device that determines the difference in oxygen activity between two gas compartments separated by an electrolyte, which is yttria-stabilized zirconia. The pump utilizes coulometric titration to either add or remove oxygen. The system is controlled by a desktop control unit, which can also be accessed via a computer. This system allows the oxygen partial pressure within the vacuum chamber to be measured and controlled, theoretically in the range from 10-36 to 100 bar. The ESL laboratory also has an emissometer, called the High-Temperature Emissivity Measurement System (HiTEMS). This system measures the spectral emissivity of materials from 600degC to 3,000degC. The system consists of a vacuum chamber, a black body source, and a Fourier Transform Infrared Spectrometer (FTIR). The system utilizes optics to swap the signal between the sample and the black body. The system was originally designed to measure the hemispherical spectral emissivity of levitated samples, which are typically 2.5mm spheres. Levitation allows emissivity measurements of molten samples, but more work is required to develop this capability. The system is currently setup measure the near-normal spectral emissivity of stationary samples, which has been used

Adapting Raman Spectra from Laboratory Spectrometers to Portable Detection Libraries

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

Weatherall, James; Barber, Jeffrey B.; Brauer, Carolyn S.

2013-02-01

Raman spectral data collected with high-resolution laboratory spectrometers are processed into a for- mat suitable for importing as a user library on a 1064nm DeltaNu rst generation, eld-deployable spectrometer prototype. The two laboratory systems used are a 1064nm Bruker spectrometer and a 785nm Kaiser spectrometer. The steps taken to compensate for device-dependent spectral resolution, wavenumber shifts between instruments, and wavenumber sensitivity variation are described.

Amino acid racemization dating of fossil bones, I. inter-laboratory comparison of racemization measurements

USGS Publications Warehouse

Bada, J.L.; Hoopes, E.; Darling, D.; Dungworth, G.; Kessels, H.J.; Kvenvolden, K.A.; Blunt, D.J.

1979-01-01

Enantiomeric measurements for aspartic acid, glutamic acid, and alanine in twenty-one different fossil bone samples have been carried out by three different laboratories using different analytical methods. These inter-laboratory comparisons demonstrate that D/L aspartic acid measurements are highly reproducible, whereas the enantiomeric measurements for the other amino acids show a wide variation between the three laboratories. At present, aspartic acid measurements are the most suitable for racemization dating of bone because of their superior analytical precision. ?? 1979.

Performance audits and laboratory comparisons for SCOS97-NARSTO measurements of speciated volatile organic compounds

NASA Astrophysics Data System (ADS)

Fujita, Eric M.; Harshfield, Gregory; Sheetz, Laurence

Performance audits and laboratory comparisons were conducted as part of the quality assurance program for the 1997 Southern California Ozone Study (SCOS97-NARSTO) to document potential measurement biases among laboratories measuring speciated nonmethane hydrocarbons (NMHC), carbonyl compounds, halogenated compounds, and biogenic hydrocarbons. The results show that measurements of volatile organic compounds (VOC) made during SCOS97-NARSTO are generally consistent with specified data quality objectives. The hydrocarbon comparison involved nine laboratories and consisted of two sets of collocated ambient samples. The coefficients of variation among laboratories for the sum of the 55 PAM target compounds and total NMHC ranged from ±5 to 15 percent for ambient samples from Los Angeles and Azusa. Abundant hydrocarbons are consistently identified by all laboratories, but discrepancies occur for olefins greater than C 4 and for hydrocarbons greater than C 8. Laboratory comparisons for halogenated compounds and biogenic hydrocarbons consisted of both concurrent ambient sampling by different laboratories and round-robin analysis of ambient samples. The coefficients of variation among participating laboratories were about 10-20 percent. Performance audits were conducted for measurement of carbonyl compounds involving sampling from a standard mixture of carbonyl compounds. The values reported by most of the laboratories were within 10-20 percent of those of the reference laboratory. Results of field measurement comparisons showed larger variations among the laboratories ranging from 20 to 40 percent for C 1-C 3 carbonyl compounds. The greater variations observed in the field measurement comparison may reflect potential sampling artifacts, which the performance audits did not address.

Airborne spectral Measurements of Surface-Atmosphere Anisotropy for Several Surfaces and Ecosystem over Southern Africa

NASA Technical Reports Server (NTRS)

Gatebe, Charles K.; King, M. D.; Arnold, G. T.; Li, J. Y.; Lau, William K. M. (Technical Monitor)

2001-01-01

The Cloud Absorption Radiometer (CAR) was flown aboard the University of Washington Convair CV-580 research aircraft and took measurements on 23 flights between August 15 and September 16. On 12 of those flights, BRF measurements were obtained over different natural surfaces and ecosystem in southern Africa. The BRF measurements were done to characterize surface anisotropy in support of SAFARI 2000 science objectives principally to validate products from NASA's EOS satellites, and to parameterize and validate BRF models. In this paper we present results of BRFs taken over two EOS validation sites: Skukuza tower, South Africa (25.0 deg S, 31.5 deg E) and Mongu tower, Zambia (15.4 deg S, 23.3 deg E). Additional sites are also considered and include, Maun tower, Botswana (20.0 deg S, 23.5 deg E), Sowa Pan, Botswana (20.6 deg S, 26.2 deg E) and Etosha Pan, Namibia (19.0 deg S, 16.0 deg E). The CAR is capable of measuring scattered light in fourteen spectral bands. The scan mirror, rotating at 100 rpm, directs the light into a Dall-Kirkham telescope where the beam is split into nine paths. Eight light beams pass through beam splitters, dichroics, and lenses to individual detectors (0.34-1.27 micrometers), and finally are registered by eight data channels. They are sampled simultaneously and continuously. The ninth beam passes through a spinning filter wheel to an InSb detector cooled by a Stirling cycle cooler. Signals registered by the ninth data channel are selected from among six spectral channels (1.55-2.30 micrometers). The filter wheel can either cycle through all six spectral bands at a prescribed interval (usually changing filter every fifth scan line), or lock onto any one of the six spectral bands and sample it continuously. To measure the BRF of the surface-atmosphere system, the University of Washington CV-580 had to bank at a comfortable roll angle of approximately 20 degrees and fly in a circle about 3 km in diameter above the surface for roughly two

Towards a measurement of the spectral runnings

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

Muñoz, Julian B.; Kovetz, Ely D.; Raccanelli, Alvise

Single-field slow-roll inflation predicts a nearly scale-free power spectrum of perturbations, as observed at the scales accessible to current cosmological experiments. This spectrum is slightly red, showing a tilt (1− n {sub s} )∼ 0.04. A direct consequence of this tilt are nonvanishing runnings α {sub s} = d n {sub s} / dlog k , and β {sub s} = dα {sub s} / dlog k , which in the minimal inflationary scenario should reach absolute values of 10{sup −3} and 10{sup −5}, respectively. In this work we calculate how well future surveys can measure these two runnings. Wemore » consider a Stage-4 (S4) CMB experiment and show that it will be able to detect significant deviations from the inflationary prediction for α {sub s} , although not for β {sub s} . Adding to the S4 CMB experiment the information from a WFIRST-like or a DESI-like survey improves the sensitivity to the runnings by ∼ 20%, and 30%, respectively. A spectroscopic survey with a billion objects, such as the SKA, will add enough information to the S4 measurements to allow a detection of α {sub s} =10{sup −3}, required to probe the single-field slow-roll inflationary paradigm. We show that only a very-futuristic interferometer targeting the dark ages will be capable of measuring the minimal inflationary prediction for β {sub s} . The results of other probes, such as a stochastic background of gravitational waves observable by LIGO, the Ly-α forest, and spectral distortions, are shown for comparison. Finally, we study the claims that large values of β {sub s} , if extrapolated to the smallest scales, can produce primordial black holes of tens of solar masses, which we show to be easily testable by the S4 CMB experiment.« less